CN117526266A - Power conversion device and power supply system - Google Patents

Abstract

The application provides a power conversion device and a power supply system. The input end of the first DC/DC conversion circuit is connected with the input end of the second DC/DC conversion circuit, and then is connected with the input end of the power conversion device in series between a positive direct current bus and a negative direct current bus, and the positive direct current bus and the negative direct current bus are used for being connected with the input end of the DC/AC converter. The output end of the first DC/DC conversion circuit and the output end of the second DC/DC conversion circuit are connected in series between the positive DC bus and the negative DC bus. The output end of the power conversion device is respectively connected with a positive direct current bus and a negative direct current bus. By adopting the power conversion device, the power transmission loss and the circuit cost of the power conversion device can be reduced.

Description

Power conversion device and power supply system

Technical field

The present application relates to the field of power supply technology, and in particular, to a power conversion device and a power supply system.

Background technique

At present, energy storage systems mainly adopt the structural diagram shown in Figure 1. As shown in Figure 1, the energy storage system includes n battery clusters (i.e., RACK 1#, RACK 2#,..., and RACK n#), n DC/DC converters, positive DC bus BUS+, and negative DC bus BUS -and DC/AC converters. Among them, the input end of each DC/DC converter in the above-mentioned n DC/DC converters is connected to a battery cluster, and the output ends of the above-mentioned n DC/DC converters are respectively connected to the positive DC bus BUS+ and the negative DC bus BUS-. . The input terminals of the DC/AC converter are respectively connected to the positive DC bus BUS+ and the negative DC bus BUS-. Based on the structural schematic diagram of the energy storage system shown in Figure 1, it can be seen that the energy storage system balances the remaining power between different battery clusters by setting its corresponding DC/DC converter in the power transmission branch of each battery cluster. This enables each battery cluster to work independently, thereby solving the problem of remaining power and voltage mismatch between battery clusters caused by multiple battery clusters being connected in parallel.

However, in the above energy storage system, the DC/DC converter is installed in the power transmission branch of the battery cluster, and the DC/DC converter needs to transmit all the power, resulting in a large power transmission loss of the DC/DC converter. In addition, the input voltage of the DC/DC converter needs to adapt to the battery cluster voltage, resulting in a wide input voltage range of the DC/DC converter. Moreover, the input voltage of the DC/AC converter is relatively high, and the output of the DC/DC converter The voltage needs to adapt to the input voltage of the DC/AC converter, resulting in a higher output voltage of the DC/DC converter, thus making the circuit cost of the DC/DC converter higher.

Contents of the invention

This application provides a power conversion device and a power supply system, which can reduce the power transmission loss and circuit cost of the power conversion device.

In a first aspect, the present application provides a power conversion device, which includes an input end, a first DC/DC conversion circuit, a second DC/DC conversion circuit, and an output end. Wherein, after the input end of the first DC/DC conversion circuit and the input end of the second DC/DC conversion circuit are connected, they are connected in series with the input end of the power conversion device between the positive DC bus and the negative DC bus. The DC bus is used to connect the input terminal of the DC/AC converter. The output terminal of the first DC/DC conversion circuit and the output terminal of the second DC/DC conversion circuit are connected in series between the positive DC bus and the negative DC bus. The output ends of the power conversion device are respectively connected to the positive DC bus and the negative DC bus.

In this embodiment, the input terminals of the two DC/DC conversion circuits in the power conversion device are connected in series with the input terminals of the power conversion device between the positive DC bus and the negative DC bus. Therefore, the two DC/DC conversion circuits It is only necessary to compensate for the voltage difference between the bus voltage (that is, the voltage between the positive DC bus and the negative DC bus) and the input voltage of the power conversion device, so that the input side of each DC/DC conversion circuit in the power conversion device The voltage is smaller, so that the transmission power of the power conversion device is smaller, which can effectively reduce the power transmission loss of the power conversion device. In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device are connected in series between the positive DC bus and the negative DC bus, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage, and because each The input side voltage of the DC/DC conversion circuit is small, so the circuit cost of the above two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of the power conversion device, and has strong applicability.

In conjunction with the first aspect, in a first possible implementation manner, the input end of the first DC/DC conversion circuit and the input end of the second DC/DC conversion circuit are connected in parallel, and then connected in series with the input end of the power conversion device at a positive DC between the bus and the negative DC bus.

In this embodiment, since the input end of the power conversion device is connected in series with the input end of any one of the above two DC/DC conversion circuits between the positive DC bus and the negative DC bus, the power conversion The device can be applied not only to a circuit structure in which its input end is connected to a positive DC bus, but also to a circuit structure in which its input end is connected to a negative DC bus. The power conversion device has various circuit structures and is highly flexible.

With reference to the first possible implementation manner of the first aspect, in a second possible implementation manner, the input end of the first DC/DC conversion circuit includes a first input end and a second input end, and the second DC/DC conversion circuit The input terminal includes a first input terminal and a second input terminal, and the input terminal of the power conversion device includes a first input terminal and a second input terminal. Wherein, the first input end of the first DC/DC conversion circuit is connected to the DC bus and the first input end of the second DC/DC conversion circuit, and the second input end of the first DC/DC conversion circuit is connected to the second DC/DC The second input terminal of the conversion circuit and the first input terminal of the power conversion device are connected to the negative DC bus.

In this embodiment, the power conversion device is suitable for application scenarios in which its input end is connected to the negative DC bus.

With reference to the first possible implementation manner of the first aspect, in a third possible implementation manner, the input end of the first DC/DC conversion circuit includes a first input end and a second input end, and the second DC/DC conversion circuit The input terminal includes a first input terminal and a second input terminal, and the input terminal of the power conversion device includes a first input terminal and a second input terminal. Wherein, the first input end of the power conversion device is connected to the DC bus, and the second input end of the power conversion device is connected to the first input end of the first DC/DC conversion circuit and the first input end of the second DC/DC conversion circuit, The second input terminal of the first DC/DC conversion circuit is connected to the second input terminal of the second DC/DC conversion circuit and the negative DC bus.

In this embodiment, the power conversion device is suitable for application scenarios in which the input end is connected to a direct DC bus.

With reference to any one of the first possible implementation manner of the first aspect to the third possible implementation manner of the first aspect, in a fourth possible implementation manner, the power conversion device further includes a controller, and the controller is used to control The input terminal voltage of the first DC/DC conversion circuit or the input terminal voltage of the second DC/DC conversion circuit reaches a first voltage, and the first voltage is the difference between the bus voltage and the input terminal voltage of the power conversion device.

In this embodiment, the power conversion device controls the input terminal voltage of any one of the two DC/DC conversion circuits to reach the first voltage, so that the input terminal voltage of each DC/DC conversion circuit Compared with when the input end of the DC/DC conversion circuit is directly connected to the DC power supply, the input end voltage of the DC/DC conversion circuit is smaller, so that the transmission power of the power conversion device is smaller, which can effectively reduce the power transmission loss of the power conversion device.

Combining any one of the first possible implementation manner of the first aspect to the third possible implementation manner of the first aspect, in a fifth possible implementation manner, the power conversion device further includes a first switch and a controller, The input terminal of the first DC/DC conversion circuit includes a first input terminal and a second input terminal, and the first switch is connected between the first input terminal and the second input terminal of the first DC/DC conversion circuit. The controller is used to control the first switch to close when the input voltage of the power conversion device is greater than or equal to the preset voltage threshold, indicating that the power conversion device does not need to compensate for the voltage difference between the bus voltage and its input terminal voltage. The controller is also used to control the first switch to turn off when the input voltage of the power conversion device is less than the preset voltage threshold, and to control the input voltage of the first DC/DC conversion circuit or the second DC/DC conversion circuit. The input terminal voltage reaches the first voltage, and the first voltage is the difference between the bus voltage and the input terminal voltage of the power conversion device.

In this embodiment, the power conversion device directly connects the input end and the output end of the power conversion device by closing the first switch without compensating the voltage difference between the bus voltage and its input end voltage, so that The first DC/DC conversion circuit and the second DC/DC conversion circuit are disabled, thereby improving the power transmission efficiency of the power conversion device.

In conjunction with the first aspect, in a sixth possible implementation manner, after the input terminal of the first DC/DC conversion circuit and the input terminal of the second DC/DC circuit are connected in series, they are connected in series with the input terminal of the power conversion device on the positive DC bus. and the negative DC bus.

In this embodiment, since the input terminals of the two DC/DC converter circuits in the power conversion device are connected in series, compared with the structure in which the input terminals of the two DC/DC converter circuits are connected in parallel, the input terminals of each DC/DC converter circuit can be The input side voltage is reduced to half of the input side voltage of each DC/DC conversion circuit when the input ends of the two DC/DC conversion circuits are connected in parallel, that is, each DC/DC conversion circuit only needs to compensate the bus voltage and power conversion device Therefore, the input side voltage of each DC/DC conversion circuit is smaller, thereby making the transmission power of the power conversion device smaller and reducing the power of the power conversion device to a greater extent. Transmission loss. In addition, devices with lower withstand voltage can be selected in each DC/DC conversion circuit, which can further reduce the circuit cost of the two DC/DC conversion circuits, thereby further reducing the circuit cost of the power conversion device and making it more applicable.

With reference to the sixth possible implementation manner of the first aspect, in a seventh possible implementation manner, the input end of the first DC/DC conversion circuit includes a first input end and a second input end, and the second DC/DC conversion circuit The input terminal includes a first input terminal and a second input terminal, and the input terminal of the power conversion device includes a first input terminal and a second input terminal. Wherein, the first input end of the first DC/DC conversion circuit is connected to the DC bus, the second input end of the first DC/DC conversion circuit is connected to the first input end of the second DC/DC circuit, and the second DC/DC conversion circuit The second input end of the circuit is connected to the first input end of the power conversion device, and the second input end of the power conversion device is connected to the negative DC bus.

In this embodiment, the power conversion device is suitable for application scenarios in which its input end is connected to the negative DC bus.

With reference to the seventh possible implementation manner of the first aspect, in an eighth possible implementation manner, the power conversion device further includes a first switch and a controller, and the first switch is connected to the first input of the first DC/DC conversion circuit. between the terminal and the first input terminal of the power conversion device. The controller is used to control the first switch to close when the input voltage of the power conversion device is greater than or equal to the preset voltage threshold, indicating that the power conversion device does not need to compensate for the voltage difference between the bus voltage and its input terminal voltage. The controller is also used to control the first switch to turn off when the input voltage of the power conversion device is less than the preset voltage threshold, and to control the input voltage of the first DC/DC conversion circuit and the second DC/DC conversion circuit. The sum of the input terminal voltages reaches a first voltage, and the first voltage is the difference between the bus voltage and the input terminal voltage of the power conversion device.

In this embodiment, the power conversion device directly connects the input end and the output end of the power conversion device by closing the first switch without compensating the voltage difference between the bus voltage and its input end voltage, so that The first DC/DC conversion circuit and the second DC/DC conversion circuit are disabled, thereby improving the power transmission efficiency of the power conversion device.

With reference to the sixth possible implementation manner of the first aspect, in a ninth possible implementation manner, the input end of the first DC/DC conversion circuit includes a first input end and a second input end, and the second DC/DC conversion circuit The input terminal includes a first input terminal and a second input terminal, and the input terminal of the power conversion device includes a first input terminal and a second input terminal. Wherein, the first input end of the power conversion device is connected to the DC bus, the second input end of the power conversion device is connected to the first input end of the first DC/DC conversion circuit, and the second input end of the first DC/DC conversion circuit is connected to The first input terminal of the second DC/DC conversion circuit and the second input terminal of the second DC/DC conversion circuit are connected to the negative DC bus.

In this embodiment, the power conversion device is suitable for application scenarios in which the input end is connected to a direct DC bus.

With reference to the ninth possible implementation manner of the first aspect, in a tenth possible implementation manner, the power conversion device further includes a first switch and a controller, the first switch is connected between the second input end of the power conversion device and the second between the second input terminals of the DC/DC conversion circuit. The controller is used to control the first switch to close when the input voltage of the power conversion device is greater than or equal to the preset voltage threshold, indicating that the power conversion device does not need to compensate for the voltage difference between the bus voltage and its input terminal voltage. The controller is also used to control the first switch to turn off when the input voltage of the power conversion device is less than a preset voltage threshold.

In this embodiment, the power conversion device directly connects the input end and the output end of the power conversion device by closing the first switch without compensating the voltage difference between the bus voltage and its input end voltage, so that The first DC/DC conversion circuit and the second DC/DC conversion circuit are disabled, thereby improving the power transmission efficiency of the power conversion device.

In combination with the seventh possible implementation manner of the first aspect or the ninth possible implementation manner of the first aspect, in an eleventh possible implementation manner, the power conversion device further includes a first switch, a second switch and a controller, The first switch is connected between the first input terminal and the second input terminal of the first DC/DC conversion circuit, and the second switch is connected between the first input terminal and the second input terminal of the second DC/DC conversion circuit. The controller is used to control the first switch and the second switch both when the input terminal voltage of the power conversion device is greater than or equal to the preset voltage threshold, indicating that the power conversion device does not need to compensate for the voltage difference between the bus voltage and its input terminal voltage. closure. The controller is also used to control both the first switch and the second switch to open when the input terminal voltage of the power conversion device is less than the preset voltage threshold, and to control the input terminal voltage of the first DC/DC conversion circuit to be connected to the second switch. The sum of the input terminal voltages of the DC/DC conversion circuit reaches a first voltage, and the first voltage is the difference between the bus voltage and the input terminal voltage of the power conversion device.

In this embodiment, the power conversion device does not need to compensate for the voltage difference between the bus voltage and its input terminal voltage, by closing the first switch and the second switch, so that the input end and the output end of the power conversion device are Directly connected, thereby disabling the first DC/DC conversion circuit and the second DC/DC conversion circuit, thereby improving the power transmission efficiency of the power conversion device. In addition, when the input ends of two DC/DC conversion circuits are connected in series, the power transmission efficiency of the power conversion device can be improved by controlling one switch or two switches. The power conversion device has various circuit structures and control methods and is highly flexible.

In combination with the sixth possible implementation manner of the first aspect, the seventh possible implementation manner of the first aspect, or the nine possible implementation manners of the first aspect, in a twelfth possible implementation manner, the power conversion device further includes a control device. The controller is used to control the sum of the input terminal voltage of the first DC/DC conversion circuit and the input terminal voltage of the second DC/DC conversion circuit to reach a first voltage. The first voltage is between the bus voltage and the input terminal voltage of the power conversion device. difference.

In this embodiment, when the input terminals of the two DC/DC conversion circuits are connected in series, the power conversion device controls the sum of the input terminal voltages of the two DC/DC conversion circuits to reach the first voltage, so that each The input terminal voltage of the DC/DC converter circuit is smaller than the input terminal voltage of each DC/DC converter circuit when the input terminals of the above two DC/DC converter circuits are connected in parallel, so that the transmission power of the power conversion device is smaller, which can effectively further Reduce power transmission losses of power conversion devices.

Combining the first aspect to the twelfth possible implementation manner of the first aspect, in a thirteenth possible implementation manner, the power conversion device includes a controller, and the controller is used to detect the first output of the first DC/DC conversion circuit. When there is a deviation between the voltage and the second output voltage of the second DC/DC conversion circuit, the power of the first DC/DC conversion circuit and/or the power of the second DC/DC conversion circuit is adjusted so that the first output The difference between the voltage and the second output voltage decreases.

In this embodiment, since the output terminals of the two DC/DC conversion circuits in the power conversion device are connected in series between the positive DC bus and the negative DC bus, the power conversion device can adjust the output terminals of the two DC/DC conversion circuits. In the way of power, the balance between the positive bus voltage and the negative bus voltage is controlled, that is, the balance of the bus midpoint (i.e., the connection point of the output terminals of the two DC/DC conversion circuits mentioned above) is controlled, thereby solving the problem of the bus midpoint caused by nonlinear loads. offset problem.

Combining the first aspect to the thirteenth possible implementation manner of the first aspect, in a fourteenth possible implementation manner, the power conversion device further includes a DC/AC converter, a positive DC bus and a negative DC bus, wherein the power The output end of the conversion device is connected to the output end of the DC/AC converter, and the input end of the DC/AC converter is connected to the positive DC bus and the negative DC bus respectively.

In this embodiment, the power conversion device can also realize conversion between direct current and alternating current, has diverse functions and circuit structures, and is highly flexible.

With reference to the fourteenth possible implementation manner of the first aspect, in a fifteenth possible implementation manner, the input end of the DC/AC converter includes a first input end and a second input end, wherein the DC/AC converter The first input terminal and the second input terminal are respectively connected to the positive DC bus and the negative DC bus. In this embodiment, the DC/AC converter is suitable for a two-level topology.

With reference to the fifteenth possible implementation manner of the first aspect, in a sixteenth possible implementation manner, the power conversion device further includes a DC neutral line, and the input end of the DC/AC converter further includes a third input end, wherein the DC The third input terminal of the /AC converter is connected to the series connection point of the output terminal of the first DC/DC conversion circuit and the output terminal of the second DC/DC conversion circuit through a DC neutral line. In this embodiment, the DC/AC converter is suitable for a three-level topology.

In a second aspect, this application provides a power supply system that includes n power conversions provided in any one of the fourteenth possible implementation manner of the first aspect to the sixteenth possible implementation manner of the first aspect. device, the input end of each power conversion device is used to connect to a DC power supply, and the output end of the power conversion device is used to connect to the AC grid or load, n is an integer greater than 1.

In this embodiment, since the input terminals of the two DC/DC conversion circuits in each power conversion device in the power supply system are connected in series or in parallel and then connected in series between the positive DC bus and the negative DC bus, each power The two DC/DC conversion circuits of the conversion device only need to compensate for the voltage difference between the bus voltage and the input terminal voltage of the power conversion device where they are located, so that the input voltage of each DC/DC conversion circuit in each power conversion device The side voltage is smaller, so that the transmission power of each power conversion device is smaller, which can effectively reduce the power transmission loss of each power conversion device, thereby reducing the power transmission loss of the power supply system. In addition, the output terminals of the two DC/DC conversion circuits in each power conversion device are connected in series between the positive DC bus and the negative DC bus, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage, and because The input side voltage of each DC/DC conversion circuit is small, so the circuit cost of the above two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of each power conversion device, so as to reduce the circuit cost of the power supply system. It is suitable for Strong sex.

Combined with the second aspect, in a first possible implementation, the DC power source is a battery cluster, and the power supply system further includes n battery clusters, and the n battery clusters are respectively connected to the input terminals of n power conversion devices. In this embodiment, the power supply system is an energy storage system, which is suitable for energy storage power supply scenarios.

In a third aspect, the present application provides a power supply system, which includes a DC/AC converter, a positive DC bus and a negative DC bus corresponding to the DC/AC converter, and n first to tenth aspects. The power conversion device provided by any one of the three possible implementations, wherein the input end of each power conversion device is used to connect a DC power supply, and the positive DC bus and the negative DC bus are connected to the input end of the DC/AC converter, The output end of the DC/AC converter is used to connect the AC grid or load, and n is an integer greater than 1.

In this embodiment, since the input terminals of the two DC/DC conversion circuits in each power conversion device in the power supply system are connected in series or in parallel and then connected in series between the positive DC bus and the negative DC bus, each power The two DC/DC conversion circuits of the conversion device only need to compensate for the voltage difference between the bus voltage and the input terminal voltage of the power conversion device where they are located, so that the input voltage of each DC/DC conversion circuit in each power conversion device The side voltage is smaller, so that the transmission power of each power conversion device is smaller, which can effectively reduce the power transmission loss of each power conversion device, thereby reducing the power transmission loss of the power supply system. In addition, the output terminals of the two DC/DC conversion circuits in each power conversion device are connected in series between the positive DC bus and the negative DC bus, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage, and because The input side voltage of each DC/DC conversion circuit is small, so the circuit cost of the above two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of each power conversion device, so as to reduce the circuit cost of the power supply system. It is suitable for Strong sex.

In conjunction with the third aspect, in a first possible implementation manner, the output end of the power conversion device includes a first output end and a second output end, and the input end of the DC/AC converter includes a first input end and a second input end. , wherein the first output end and the second output end of the power conversion device are respectively connected to the positive DC bus and the negative DC bus, and the first input end and the second input end of the DC/AC converter are respectively connected to the positive DC bus and the negative DC bus. . In this embodiment, the DC/AC converter is suitable for a two-level topology.

With reference to the first possible implementation manner of the third aspect, in a second possible implementation manner, the power supply system further includes a DC neutral line corresponding to the DC/AC converter, and the output end of the power conversion device further includes a third output end, DC The input terminal of the /AC converter also includes a third input terminal. Wherein, the third output end of the power conversion device is connected to the series connection point between the output end of the first DC/DC conversion circuit and the output end of the second DC/DC conversion circuit. The third output terminal of the power conversion device and the third input terminal of the DC/AC converter are both connected to the DC neutral line. In this embodiment, the DC/AC converter is suitable for a three-level topology.

Combined with the third aspect, in a third possible implementation, the number of DC/AC converters is n, and the n DC/AC converters correspond to n positive DC buses and n negative DC buses, and n DC/AC converters correspond to n positive DC buses and n negative DC buses. The AC converter has a one-to-one correspondence with n positive DC buses, the n DC/AC converters have a one-to-one correspondence with the n negative DC buses, the n DC/AC converters have a one-to-one correspondence with the n power conversion devices, and the n DC The input end of each DC/AC converter in the /AC converter is respectively connected to the corresponding positive DC bus and negative DC bus of each DC/AC converter.

In this embodiment, the number of DC/AC converters in the power supply system can be multiple, with various structures and high flexibility.

With reference to the third possible implementation manner of the third aspect, in a fourth possible implementation manner, the output end of the power conversion device includes a first output end and a second output end, and the input end of each DC/AC converter includes first input terminal and second input terminal. Wherein, the first input end of each DC/AC converter is connected to the first output end of the power conversion device corresponding to each DC/AC converter through the positive DC bus corresponding to each DC/AC converter, and each DC/ The second input terminal of the AC converter is connected to the second output terminal of the power conversion device corresponding to each DC/AC converter through the negative DC bus corresponding to each DC/AC converter. In this embodiment, the DC/AC converter is suitable for a two-level topology.

With reference to the fourth possible implementation manner of the third aspect, in a fifth possible implementation manner, the power supply system further includes n DC neutral lines corresponding to n DC/AC converters, and the output end of the power conversion device further includes a third The output terminal and the input terminal of each DC/AC converter also include a third input terminal. Wherein, the third output end of the power conversion device is connected to the series connection point between the output end of the first DC/DC conversion circuit and the output end of the second DC/DC conversion circuit. The third input end of each DC/AC converter is connected to the third output end of the power conversion device corresponding to each DC/AC converter through the corresponding DC neutral line of each DC/AC converter, n DC/AC converters One-to-one correspondence with n DC neutral lines. In this embodiment, the DC/AC converter is suitable for a three-level topology.

Combining any one of the third to fifth possible implementations of the third aspect, in a sixth possible implementation, the DC power supply is a battery cluster, and the power supply system further includes n battery clusters, n battery clusters Connect the input terminals of n power conversion devices respectively. In this embodiment, the power supply system is an energy storage system, which is suitable for energy storage power supply scenarios.

Description of drawings

Figure 1 is a schematic structural diagram of an energy storage system provided by the prior art;

Figure 2 is a schematic diagram of the application scenario of the power supply system provided by this application;

Figure 3 is a schematic structural diagram of the power conversion device provided by this application;

Figure 4a is another structural schematic diagram of the power conversion device provided by this application;

Figure 4b is another structural schematic diagram of the power conversion device provided by this application;

Figure 4c is another structural schematic diagram of the power conversion device provided by this application;

Figure 4d is another structural schematic diagram of the power conversion device provided by this application;

Figure 4e is another structural schematic diagram of the power conversion device provided by this application;

Figure 4f is another structural schematic diagram of the power conversion device provided by this application;

Figure 5 is another structural schematic diagram of the power conversion device provided by this application;

Figure 6a is another structural schematic diagram of the power conversion device provided by this application;

Figure 6b is another structural schematic diagram of the power conversion device provided by this application;

Figure 6c is another structural schematic diagram of the power conversion device provided by this application;

Figure 6d is another structural schematic diagram of the power conversion device provided by this application;

Figure 6e is another structural schematic diagram of the power conversion device provided by this application;

Figure 6f is another structural schematic diagram of the power conversion device provided by this application;

Figure 7 is another structural schematic diagram of the power conversion device provided by this application;

Figure 8a is another structural schematic diagram of the power conversion device provided by this application;

Figure 8b is another structural schematic diagram of the power conversion device provided by this application;

Figure 8c is another structural schematic diagram of the power conversion device provided by this application;

Figure 8d is another structural schematic diagram of the power conversion device provided by this application;

Figure 8e is another structural schematic diagram of the power conversion device provided by this application;

Figure 8f is another structural schematic diagram of the power conversion device provided by this application;

Figure 9 is another structural schematic diagram of the power conversion device provided by this application;

Figure 10a is another structural schematic diagram of the power conversion device provided by this application;

Figure 10b is another structural schematic diagram of the power conversion device provided by this application;

Figure 10c is another structural schematic diagram of the power conversion device provided by this application;

Figure 10d is another structural schematic diagram of the power conversion device provided by this application;

Figure 10e is another structural schematic diagram of the power conversion device provided by this application;

Figure 10f is another structural schematic diagram of the power conversion device provided by this application;

Figure 11a is a schematic structural diagram of the power supply system provided by this application;

Figure 11b is another structural schematic diagram of the power supply system provided by this application;

Figure 11c is another structural schematic diagram of the power supply system provided by this application;

Figure 11d is another structural schematic diagram of the power supply system provided by this application;

Figure 12a is another structural schematic diagram of the power supply system provided by this application;

Figure 12b is another structural schematic diagram of the power supply system provided by this application;

Figure 12c is another structural schematic diagram of the power supply system provided by this application;

Figure 12d is another structural schematic diagram of the power supply system provided by this application;

Figure 12e is another structural schematic diagram of the power supply system provided by this application;

Figure 12f is another structural schematic diagram of the power supply system provided by this application;

Figure 12g is another structural schematic diagram of the power supply system provided by this application;

Figure 12h is another structural schematic diagram of the power supply system provided by this application;

Figure 13 is another structural schematic diagram of the power supply system provided by this application;

Figure 14 is another structural schematic diagram of the power supply system provided by this application.

Detailed ways

The power conversion device and power supply system provided by this application can be applied to various application fields such as energy storage power generation, photovoltaic power generation, new energy smart microgrid, and power transmission and distribution. The power conversion device provided by this application can be an energy storage converter (Power Conversion System, PCS), photovoltaic inverter, DC/DC converter, etc., and is suitable for different application scenarios, such as energy storage power supply scenarios, photovoltaic power supply scenarios, optical-storage hybrid power supply scenarios, uninterrupted power supply (UPS) power supply scenarios, etc. The following takes the energy storage power supply scenario as an example for explanation.

Refer to Figure 2, which is a schematic diagram of the application scenario of the power supply system provided by this application. The power supply system provided by this application includes n DC power supplies, n power conversion devices, DC/AC converters, and the positive DC bus and negative DC bus corresponding to the DC/AC converter, where n is an integer greater than 1. As shown in Figure 2, in the energy storage power supply scenario, the power supply system provided by this application is the energy storage system shown in Figure 2, and the DC power supply, power conversion device and DC/AC converter provided by this application are shown in Figure 2 respectively. The energy storage battery cluster, DC/DC converter and DC/AC converter are shown in the figure. The positive DC bus and negative DC bus corresponding to the DC/AC converter provided by this application are the positive DC bus BUS+ and the negative DC bus shown in Figure 2 respectively. DC bus BUS-. Each of the n DC/DC converters includes an input terminal, a first DC/DC conversion circuit, a second DC/DC conversion circuit and an output terminal. Wherein, after the input terminal of the first DC/DC converting circuit and the input terminal of the second DC/DC converting circuit are connected in series, they are connected in series with the input terminal of the DC/DC converter between the positive DC bus BUS+ and the negative DC bus BUS-. The output terminal of the first DC/DC converter circuit and the output terminal of the second DC/DC converter circuit are connected in series between the two output terminals of the DC/DC converter, and the two output terminals of the DC/DC converter are respectively connected to the positive DC Bus BUS+ and negative DC bus BUS-. The input end of the DC/AC converter is connected to the positive DC bus BUS+ and the negative DC bus BUS- respectively, and the output end of the DC/AC converter is connected to the AC power grid or load (such as household equipment).

After the energy storage system starts operating, each DC/DC converter controls the first DC/DC conversion circuit and the second DC/DC conversion circuit to convert the DC power output by the battery cluster connected to the respective input end into a target voltage. DC power and output to the positive DC bus BUS+ and the negative DC bus BUS-. The DC/AC converter inverts the DC power obtained from the positive DC bus BUS+ and the negative DC bus BUS- into AC power, thereby supplying power to various types of electrical equipment such as AC grids or loads.

It can be understood that since the input terminals of the two DC/DC conversion circuits in the DC/DC converter are connected in series with the input terminal of the DC/DC converter between the positive DC bus BUS+ and the negative DC bus BUS-, therefore, the two A DC/DC conversion circuit only needs to compensate for the voltage difference between the bus voltage (that is, the voltage between the positive DC bus BUS+ and the negative DC bus BUS-) and the input voltage of the DC/DC converter, so that the DC/DC The input side voltage of each DC/DC converter circuit in the converter is small, so that the transmission power of the DC/DC converter is small, which can effectively reduce the power transmission loss of the DC/DC converter and thereby improve the efficiency of the DC/DC converter. power transfer efficiency. In addition, the output terminals of the two DC/DC conversion circuits in the DC/DC converter are connected in series between the positive DC bus BUS+ and the negative DC bus BUS-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. , and because the input side voltage of each DC/DC conversion circuit is small, the circuit cost of the first DC/DC conversion circuit and the second DC/DC conversion circuit can be effectively reduced, thereby reducing the circuit cost of the DC/DC converter. , strong applicability.

The above is only an example of the application scenarios of the power supply system provided by this application, and is not exhaustive. This application does not limit the application scenarios.

The working principles of the power conversion device and power supply system provided by this application will be illustrated below with reference to Figures 3 to 14.

Referring to Figure 3, Figure 3 is a schematic structural diagram of the power conversion device provided by this application. As shown in FIG. 3 , the power conversion device 11 includes an input terminal, a first DC/DC conversion circuit 111 , a second DC/DC conversion circuit 112 and an output terminal. The input terminal of the power conversion device 11 includes a first input terminal in ₁₁₊ and a second input terminal in _11- , and the output terminal of the power conversion device 11 includes a first output terminal out ₁₁₊ and a second output terminal out _11- . The input terminals in ₁₁₊ and in _11- of the power conversion device 11 are used to connect the positive pole and the negative pole of the DC power supply 31 respectively. The DC power supply 31 includes photovoltaic strings or battery clusters.

After the input terminal in ₁₁₁ of the first DC/DC conversion circuit 111 is connected to the input terminal in ₁₁₂ of the second DC/DC conversion circuit 112, it is connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-. between. Exemplarily, one end formed by connecting the input terminal in ₁₁₁ of the first DC/DC conversion circuit 111 and the input terminal in ₁₁₂ of the second DC/DC conversion circuit 112 is connected to the DC bus BUS1+. Specifically, the first DC/ One end formed by connecting the input terminal in ₁₁₁ of the DC conversion circuit 111 and the input terminal in ₁₁₂ of the second DC/DC conversion circuit 112 is connected to the DC bus BUS1+ through the first output terminal out ₁₁₊ of the power conversion device 11 . The other end formed by connecting the input terminal in ₁₁₁ of the first DC/DC conversion circuit 111 and the input terminal in ₁₁₂ of the second DC/DC conversion circuit 112 is connected to the first input terminal in ₁₁₊ of the power conversion device 11 . The second input terminal in _{11 -} of the power conversion device 11 is connected to the negative DC bus BUS1 -. Specifically, the second input terminal in _{11 -} of the power conversion device 11 is connected to the negative DC bus through the output terminal out _{11 -} of the power conversion device 11. BUS1-. The positive DC bus BUS1+ and the negative DC bus BUS1- are used to connect the input terminals of the DC/AC converter 21, where the input terminals of the DC/AC converter 21 include a first input terminal in ₂₁₊ and a second input terminal in _21-. . Specifically, the positive DC bus BUS1+ and the negative DC bus BUS1- are connected to the first input terminal in ₂₁₊ and the second input terminal in _21- of the DC/AC converter 21 respectively. Here, the input terminal in ₁₁₁ of the first DC/DC conversion circuit 111 and the input terminal in ₁₁₂ of the second DC/DC conversion circuit 112 may be connected in series or in parallel, as illustrated by a dotted line in FIG. 3 .

The output end of the first DC/DC conversion circuit 111 and the output end of the second DC/DC conversion circuit 112 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, and the output ends of the power conversion device 11 are respectively connected to the positive DC bus. BUS1+ and negative DC bus BUS1-. Wherein, the output terminal of the first DC/DC conversion circuit 111 includes a first output terminal out ₁₁₁₊ and a second output terminal out _111- , and the output terminal of the second DC/DC conversion circuit 112 includes a first output terminal out ₁₁₂₊ and The second output terminal is out _112- . Specifically, the first output terminal out ₁₁₁₊ of the first DC/DC conversion circuit 111 is connected to the first output terminal out ₁₁₊ of the power conversion device 11, and the second output terminal out _111- of the first DC/DC conversion circuit 111 is connected. The first output terminal out ₁₁₂₊ of the second DC/DC conversion circuit 112 is connected, and the second output terminal out 112- of the second DC/DC conversion circuit 112 is connected to the second output terminal out _11- of the power conversion device ₁₁ . The first output terminal out ₁₁₊ of the power conversion device 11 is connected to the positive DC bus BUS1+, and the second output terminal out _11- of the power conversion device 11 is connected to the negative DC bus BUS1-.

In addition, the above two DC/DC conversion circuits are isolated DC/DC conversion circuits or non-isolated DC/DC conversion circuits, and either DC/DC conversion circuit can achieve voltage boosting and/or voltage reduction. The topology of the DC/AC converter can be a two-level topology, a three-level topology or any other structure. The input end and the output end of the power conversion device 11 provided by this application are both input and output bidirectional ends. Here, the input and output bidirectional terminals are terminals that can be used as both input terminals and output terminals. Correspondingly, the input end and output end of any DC/DC conversion circuit in the first DC/DC conversion circuit 111 and the second DC/DC conversion circuit 112, as well as the input end and output end of the DC/AC converter are also input. Output bidirectional terminal.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series with the input terminals of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, The two DC/DC conversion circuits only need to compensate for the voltage difference between the bus voltage and the input voltage of the power conversion device 11, so that the input side voltage of each DC/DC conversion circuit in the power conversion device 11 is smaller, thereby Making the transmission power of the power conversion device 11 smaller can effectively reduce the power transmission loss of the power conversion device 11 , thereby improving the power transmission efficiency of the power conversion device 11 . In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. In addition, since the input side voltage of each DC/DC conversion circuit is small, the circuit cost of the above two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of the power conversion device 11 and having strong applicability.

It should be noted that when the DC power supply 31 is a battery cluster, the power conversion device 11 is a PCS or a DC/DC converter; when the DC power supply 31 is a photovoltaic string, the power conversion device 11 is a photovoltaic inverter or photovoltaic optimizer. . Specifically, when the DC power supply 31 is a photovoltaic string and the power conversion device 11 includes the DC/AC converter 21, the power conversion device 11 is a photovoltaic inverter; when the DC power supply 31 is a photovoltaic string and the power conversion device 11 does not When including the DC/AC converter 21, the power conversion device 11 is a photovoltaic optimizer. For the convenience of description, the power conversion device 11 shown in FIG. 3 will be introduced in detail below by taking the DC power source as a battery cluster as an example.

For example, see FIG. 4a , which is another structural schematic diagram of the power conversion device provided by the present application. As shown in Figure 4a, compared with the power conversion device 11 shown in Figure 3, the input end of the first DC/DC conversion circuit 111 and the second DC/DC conversion circuit 112 in the power conversion device 11 shown in Figure 4a The input terminals are connected in parallel. Wherein, the input terminal of the first DC/DC conversion circuit 111 includes a first input terminal in ₁₁₁₊ and a second input terminal in _111- , and the input terminal of the second DC/DC conversion circuit 112 includes a first input terminal in ₁₁₂₊ and Second input terminal in _112- .

Specifically, the first input terminal in _{111 +} of the first DC/DC conversion circuit 111 is connected to the DC bus BUS1 + through the first output terminal out ₁₁ + of the power conversion device 11 . The first input terminal in ₁₁₁₊ of the first DC/DC conversion circuit 111 is also connected to the first input terminal in ₁₁₂₊ of the second DC/DC conversion circuit 112, and the second input terminal in _{111 of the first DC/DC conversion circuit 111 -Connect} the second input terminal in _112- of the second DC/DC conversion circuit 112. The second input terminal in _{112 -} of the second DC/DC conversion circuit 112 is also connected to the first input terminal in ₁₁₊ of the power conversion device 11 , and the second input terminal in ₁₁ - of the power conversion device 11 passes through the first input terminal in 11+ of the power conversion device 11 The second output terminal out ₁₁ - is connected to the negative DC bus BUS1-.

Here, in the power conversion device 11 shown in Figure 4a, the output end of the first DC/DC conversion circuit 111, the output end of the second DC/DC conversion circuit 112, the output end of the power conversion device 11 and the positive and negative DC buses (i.e. For the connection relationship between the positive DC bus BUS1+ and the negative DC bus BUS1-), please refer to the description of the corresponding part of the power conversion device 11 shown in Figure 3, which will not be described again here.

In addition, the power conversion device 11 also includes a controller 113, a positive bus capacitor C11 and a negative bus capacitor C12. The positive bus capacitor C11 is connected to the first output terminal out ₁₁₁₊ and the second output terminal out of the first DC/DC conversion circuit 111. ₁₁₁ -, the negative bus capacitor C12 is connected between the first output terminal out ₁₁₂₊ and the second output terminal out ₁₁₂ - of the second DC/DC conversion circuit 112.

In one embodiment, after the power conversion device 11 starts to operate, the controller 113 controls the input terminal voltage of the first DC/DC conversion circuit 111 or the second voltage by controlling the conduction time of the switch in the DC/DC conversion circuit. The input voltage of the DC/DC conversion circuit 112 reaches a first voltage, and the first voltage is the difference between the bus voltage and the input voltage of the power conversion device 11 to compensate for the difference between the bus voltage and the input voltage of the power conversion device 11 the difference between.

Optionally, in order to further improve the power transmission efficiency of the power conversion device 11, the power conversion device 11 also includes a first switch K11. The first switch K11 is connected to the first input terminal in ₁₁₁₊ of the first DC/DC conversion circuit 111 and Second input terminal in ₁₁₁ - between.

In one embodiment, when the input terminal voltage of the power conversion device 11 (ie, the battery voltage of the battery cluster 31) is less than the preset voltage threshold, the controller 113 controls the first switch K11 to turn off, and controls the first DC/ The input terminal voltage of the DC conversion circuit 111 or the input terminal voltage of the second DC/DC conversion circuit 112 reaches a first voltage. The first voltage is the difference between the bus voltage and the input terminal voltage of the power conversion device 11 to compensate for the bus voltage. The difference between the voltage and the input terminal voltage of the power conversion device 11. In addition, when the input voltage of the power conversion device 11 is greater than or equal to the preset voltage threshold, indicating that the power conversion device 11 does not need to compensate for the voltage difference between the bus voltage and its input voltage, the controller 113 controls the first switch K11 closed, so that the input end and the output end of the power conversion device 11 are directly connected, thereby disabling the first DC/DC conversion circuit 111 and the second DC/DC conversion circuit 112, thereby improving the power transmission efficiency of the power conversion device 11.

In the process of compensating the difference between the bus voltage and the input terminal voltage of the power conversion device 11 or controlling the first switch K11, the controller 113 also obtains the first output voltage of the first DC/DC conversion circuit 111 (i.e., the positive bus The positive bus voltage of the capacitor C11) and the second output voltage of the second DC/DC conversion circuit 112 (that is, the negative bus voltage of the negative bus capacitor C12), and when there is a deviation between the positive bus voltage and the negative bus voltage, The power of the first DC/DC conversion circuit 111 and/or the power of the second DC/DC conversion circuit 112 is adjusted so that the difference between the positive bus voltage and the negative bus voltage is reduced. Among them, the power of the DC/DC conversion circuit can be input power or output power.

In an optional embodiment, assuming that the power flow direction of the power conversion device is from the DC/AC converter 21 to the battery cluster 31 , when the positive bus voltage is less than the negative bus voltage, the controller 113 increases the first DC /DC conversion circuit 111 by increasing the output power of the first DC/DC conversion circuit 111 to increase the positive bus voltage, or by reducing the output current of the second DC/DC conversion circuit 112 by reducing The output power of the first DC/DC conversion circuit 111 is reduced by reducing the negative bus voltage, or by increasing the output current of the first DC/DC conversion circuit 111 and reducing the output current of the second DC/DC conversion circuit 112, Increase the output power of the first DC/DC conversion circuit 111 and reduce the output power of the second DC/DC conversion circuit 112 to increase the positive bus voltage and reduce the negative bus voltage, thereby making the positive bus voltage and the negative bus voltage between The difference decreases.

In another optional embodiment, assuming that the power flow direction of the power conversion device is from the DC/AC converter 21 to the battery cluster 31 , when the positive bus voltage is greater than the negative bus voltage, the controller 113 reduces the first The output current of the DC/DC conversion circuit 111 is reduced by reducing the output power of the first DC/DC conversion circuit 111 to reduce the positive bus voltage, or by increasing the output current of the second DC/DC conversion circuit 112, increasing the output power of the second DC/DC conversion circuit 112 to increase the negative bus voltage, or by reducing the output current of the first DC/DC conversion circuit 111 and increasing the output current of the second DC/DC conversion circuit 112 In this way, the output power of the first DC/DC conversion circuit 111 is reduced and the output power of the second DC/DC conversion circuit 112 is increased to reduce the positive bus voltage and increase the negative bus voltage, thereby making the positive bus voltage equal to the negative bus voltage. The difference between voltages decreases.

It can be understood that since the output terminals of the two DC/DC conversion circuits are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, the power conversion device 11 can adjust the power of the two DC/DC conversion circuits. In this way, the balance between the positive bus voltage and the negative bus voltage is controlled, that is, the balance of the bus midpoint (i.e., the connection point of the output terminals of the two DC/DC conversion circuits mentioned above) is controlled, thereby solving the bus midpoint deviation caused by the nonlinear load. migration problem.

Optionally, the power conversion device 11 can also be adapted to a three-level topology DC/AC converter. For details, please refer to the power conversion device shown in Figure 4b. As shown in Figure 4b, the output end of the power conversion device 11 also includes a third output end out _11N . The third output end out _11N of the power conversion device 11 is connected to the second output end out _{111 - of the first DC/DC conversion circuit 111} . The series connection point with the first output terminal out ₁₁₂₊ of the second DC/DC conversion circuit 112. The third output terminal out _11N of the power conversion device 11 and the third input terminal in _21N of the DC/AC converter 21 are both connected to the DC neutral line BUS1N. It can be understood that the power conversion device 11 can be adapted not only to a two-level topology DC/AC converter, but also to a three-level topology DC/AC converter, and has strong applicability.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in parallel and connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, Each DC/DC conversion circuit only needs to compensate for the voltage difference between the bus voltage and the input voltage of the power conversion device 11, so that the input side voltage of each DC/DC conversion circuit in the power conversion device 11 is smaller, thereby Making the transmission power of the power conversion device 11 smaller can effectively reduce the power transmission loss of the power conversion device 11 , thereby improving the power transmission efficiency of the power conversion device 11 . In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. In addition, since the input side voltage of each DC/DC conversion circuit is small, the circuit cost of the above two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of the power conversion device 11 and having strong applicability.

For example, see Figure 4c, which is another schematic structural diagram of the power conversion device provided by the present application. As shown in Figure 4c, compared with the power conversion device 11 shown in Figure 4a, the input end of the first DC/DC conversion circuit 111 and the second DC/DC conversion circuit 112 in the power conversion device 11 shown in Figure 4c The input terminals are connected in series.

Specifically, the first input terminal in _{111 +} of the first DC/DC conversion circuit 111 is connected to the DC bus BUS1 + through the first output terminal out ₁₁ + of the power conversion device 11 . The second input terminal in _{111 -} of the first DC/DC conversion circuit 111 is connected to the first input terminal in ₁₁₂₊ of the second DC/DC conversion circuit 112 , and the second input terminal in _{112 - of the second DC/DC conversion circuit 112} The first input terminal in ₁₁₊ of the power conversion device 11 is connected, and the second input terminal in _11- of the power conversion device 11 is connected to the negative DC bus BUS1- through the second output terminal out _11- of the power conversion device 11.

Optionally, the power conversion device 11 also includes a first switch K11. The first switch K11 is connected between the first input terminal in ₁₁₊ of the power conversion device 11 and the first input terminal in 111+ of the first DC/DC conversion circuit ₁₁₁ . between.

In one embodiment, when the input terminal voltage of the power conversion device 11 (ie, the battery voltage of the battery cluster 31) is less than the preset voltage threshold, the controller 113 controls the first switch K11 to turn off, and controls the first DC/ The sum of the input terminal voltage of the DC conversion circuit 111 and the input terminal voltage of the second DC/DC conversion circuit 112 reaches a first voltage. The first voltage is the difference between the bus voltage and the input terminal voltage of the power conversion device 11, so that The difference between the bus voltage and the input terminal voltage of the power conversion device 11 is compensated. In addition, when the input voltage of the power conversion device 11 is greater than or equal to the preset voltage threshold, indicating that the power conversion device 11 does not need to compensate for the voltage difference between the bus voltage and its input voltage, the controller 113 controls the first switch K11 closed, so that the input end and the output end of the power conversion device 11 are directly connected, thereby disabling the first DC/DC conversion circuit 111 and the second DC/DC conversion circuit 112, thereby improving the power transmission efficiency of the power conversion device 11.

In the process of compensating the difference between the bus voltage and the input terminal voltage of the power conversion device 11 or controlling the first switch K11, the controller 113 also controls the bus when there is a deviation between the positive bus voltage and the negative bus voltage. Midpoint balance.

Here, in the power conversion device 11 shown in FIG. 4c , except for the connection relationship between the input terminal of the first DC/DC conversion circuit 111 and the input terminal of the second DC/DC conversion circuit 112 and the connection relationship of the first switch K11 The specific connection relationship of other parts, as well as the power conversion device 11 to control the bus midpoint balance, and the power conversion device 11 to compensate for the difference between the bus voltage and its input end voltage when the power conversion device 11 does not include the first switch K11 For the implementation method, please refer to the description of the corresponding parts of the power conversion device 11 shown in Figure 4a, which will not be described again here.

Optionally, the power conversion device 11 can also be adapted to a three-level topology DC/AC converter. For details, please refer to the power conversion device shown in Figure 4d. As shown in Figure 4d, the output end of the power conversion device 11 also includes a third output end out _11N . Here, for the specific connection relationship of the third output end out _11N of the power conversion device 11, please refer to the power conversion device shown in Figure 4b. The description of the corresponding parts in 11 will not be repeated here. It can be understood that the power conversion device 11 can be adapted not only to a two-level topology DC/AC converter, but also to a three-level topology DC/AC converter, and has strong applicability.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, Compared with the structure in which the input terminals of two DC/DC converter circuits are connected in parallel, the input side voltage of each DC/DC converter circuit can be reduced to that of each DC/DC converter when the input terminals of two DC/DC converter circuits are connected in parallel. Half of the input side voltage of the circuit, that is, each DC/DC conversion circuit only needs to compensate half of the voltage difference between the bus voltage and the input terminal voltage of the power conversion device, so that each DC/DC converter in the power conversion device 11 The input side voltage of the circuit is smaller, so that the transmission power of the power conversion device 11 is smaller, which can reduce the power transmission loss of the power conversion device 11 to a greater extent, thereby improving the power transmission efficiency of the power conversion device 11 to a greater extent. In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. And since the input side voltage of each DC/DC converter circuit is reduced to half of the input side voltage of each DC/DC converter circuit when the input terminals of two DC/DC converter circuits are connected in parallel, therefore, each DC/DC converter Devices with lower withstand voltage can be selected in the circuit, which can further reduce the circuit cost of the above two DC/DC conversion circuits, thereby further reducing the circuit cost of the power conversion device 11 and improving the applicability.

For example, see Figure 4e, which is another schematic structural diagram of the power conversion device provided by this application. As shown in Figure 4e, compared with the power conversion device 11 shown in Figure 4c, the number and position of switches in the power conversion device 11 shown in Figure 4e are different. Specifically, the power conversion device 11 includes a first switch K11 and a second switch K12. The first switch K11 is connected between the first input terminal in ₁₁₁₊ and the second input terminal in _111- of the first DC/DC conversion circuit 111. , the second switch K12 is connected between the first input terminal in ₁₁₂₊ and the second input terminal in _112- of the second DC/DC conversion circuit 112. Here, for the specific connection relationships of other parts in the power conversion device 11 shown in FIG. 4e except for the switches, please refer to the description of the corresponding parts in the power conversion device 11 shown in FIG. 4c and will not be described again here.

In one embodiment, when the input terminal voltage of the power conversion device 11 (ie, the battery voltage of the battery cluster 31 ) is less than the preset voltage threshold, the controller 113 controls the first switch K11 and the second switch K12 to open, and The sum of the input terminal voltage of the first DC/DC conversion circuit 111 and the input terminal voltage of the second DC/DC conversion circuit 112 is controlled to reach a first voltage. The first voltage is between the bus voltage and the input terminal voltage of the power conversion device 11 to compensate for the difference between the bus voltage and the input terminal voltage of the power conversion device 11 . In addition, when the input voltage of the power conversion device 11 is greater than or equal to the preset voltage threshold, indicating that the power conversion device 11 does not need to compensate for the voltage difference between the bus voltage and its input voltage, the controller 113 controls the first switch K11 and the second switch K12 are both closed, so that the input end and the output end of the power conversion device 11 are directly connected, so that the first DC/DC conversion circuit 111 and the second DC/DC conversion circuit 112 do not work, thereby improving the power conversion device. Power transfer efficiency of 11.

In addition, the power conversion device 11 can also control the bus midpoint balance by adjusting the power of the first DC/DC conversion circuit 111 and/or the power of the second DC/DC conversion circuit 112 . Here, the power conversion device 11 controls the bus midpoint balance and the specific implementation method of the power conversion device 11 compensating the difference between the bus voltage and its input terminal voltage when the power conversion device 11 does not include the first switch K11, please refer to Figure 4a. The description of the corresponding parts of the power conversion device 11 shown above will not be repeated here.

Optionally, the power conversion device 11 can also be adapted to a three-level topology DC/AC converter. For details, please refer to the power conversion device shown in Figure 4f. As shown in Figure 4f, the output end of the power conversion device 11 also includes a third output end out _11N . Here, for the specific connection relationship of the third output end out _11N of the power conversion device 11, please refer to the power conversion device 11 shown in Figure 4b. The description of the corresponding parts will not be repeated here. It can be understood that the power conversion device 11 can be adapted not only to a two-level topology DC/AC converter, but also to a three-level topology DC/AC converter, and has strong applicability.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, Compared with the structure in which the input terminals of two DC/DC converter circuits are connected in parallel, the input side voltage of each DC/DC converter circuit can be reduced to that of each DC/DC converter when the input terminals of two DC/DC converter circuits are connected in parallel. Half of the input side voltage of the circuit, that is, each DC/DC conversion circuit only needs to compensate half of the voltage difference between the bus voltage and the input terminal voltage of the power conversion device, so that each DC/DC converter in the power conversion device 11 The input side voltage of the circuit is smaller, so that the transmission power of the power conversion device 11 is smaller, which can reduce the power transmission loss of the power conversion device 11 to a greater extent, thereby improving the power transmission efficiency of the power conversion device 11 to a greater extent. In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. And since the input side voltage of each DC/DC converter circuit is reduced to half of the input side voltage of each DC/DC converter circuit when the input terminals of two DC/DC converter circuits are connected in parallel, therefore, each DC/DC converter Devices with lower withstand voltage can be selected in the circuit, which can further reduce the circuit cost of the above two DC/DC conversion circuits, thereby further reducing the circuit cost of the power conversion device 11 and improving the applicability. Furthermore, when the input ends of two DC/DC conversion circuits are connected in series, the number and positions of switches in the power conversion device 11 are diverse, so that the power conversion device 11 has diverse structures and high flexibility.

Referring to Figure 5, Figure 5 is another structural schematic diagram of the power conversion device provided by the present application. As shown in FIG. 5 , the power conversion device 11 has a symmetrical structure of the power conversion device 11 shown in FIG. 3 . Compared with the power conversion device 11 shown in FIG. 3 , the input terminal of the power conversion device 11 shown in FIG. 5 is connected in a different manner. Specifically, the first input terminal in ₁₁₊ of the power conversion device 11 is connected to the DC bus BUS1+ through the first output terminal out ₁₁₊ of the power conversion device 11, and the second input terminal in _11- of the power conversion device 11 is connected to the first The input terminal in 111 of the DC/DC conversion circuit ₁₁₁ and the input terminal in ₁₁₂ of the second DC/DC conversion circuit 112 are connected to form one end. The input terminal in ₁₁₁ of the first DC/DC conversion circuit 111 and the second DC/DC The other end formed after the input terminal in ₁₁₂ of the conversion circuit 112 is connected is connected to the negative DC bus BUS1- through the second output terminal out _11- of the power conversion device 11. Here, for the connection relationships of other parts of the power conversion device 11 except the connection relationship of the input terminals, please refer to the description of the corresponding parts of the power conversion device 11 shown in FIG. 3 and will not be described again here.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series with the input terminals of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, The two DC/DC conversion circuits only need to compensate for the voltage difference between the bus voltage and the input voltage of the power conversion device 11, so that the input side voltage of each DC/DC conversion circuit in the power conversion device 11 is smaller, thereby Making the transmission power of the power conversion device 11 smaller can effectively reduce the power transmission loss of the power conversion device 11 , thereby improving the power transmission efficiency of the power conversion device 11 . In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. In addition, since the input side voltage of each DC/DC conversion circuit is small, the circuit cost of the above two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of the power conversion device 11 and having strong applicability.

For the convenience of description, the power conversion device 11 shown in FIG. 5 will be introduced in detail below by taking the DC power source as a battery cluster as an example.

For example, see FIG. 6a , which is another structural schematic diagram of the power conversion device provided by the present application. As shown in Figure 6a, compared with the power conversion device 11 shown in Figure 5, the input end of the first DC/DC conversion circuit 111 and the second DC/DC conversion circuit 112 in the power conversion device 11 shown in Figure 6a The input terminals are connected in parallel. Wherein, the input terminal of the first DC/DC conversion circuit 111 includes a first input terminal in ₁₁₁₊ and a second input terminal in _111- , and the input terminal of the second DC/DC conversion circuit 112 includes a first input terminal in ₁₁₂₊ and Second input terminal in _112- .

Specifically, the first input terminal in ₁₁₊ of the power conversion device 11 is connected to the DC bus BUS1+ through the first output terminal out ₁₁₊ of the power conversion device 11, and the second input terminal in _11- of the power conversion device 11 is connected to the first The first input terminal in ₁₁₁₊ of the DC/DC conversion circuit 111. The first input terminal in ₁₁₁₊ of the first DC/DC conversion circuit 111 is connected to the first input terminal in ₁₁₂₊ of the second DC/DC conversion circuit 112, and the second input terminal in _111- of the first DC/DC conversion circuit 111 is connected. Connect the second input terminal in _112- of the second DC/DC conversion circuit 112. The second input terminal in _{112 -} of the second DC/DC conversion circuit 112 is connected to the negative DC bus BUS1 - through the second output terminal out ₁₁ - of the power conversion device 11 .

Here, in the power conversion device 11 shown in FIG. 6a, in addition to the input end of the first DC/DC conversion circuit 111, the input end of the second DC/DC conversion circuit 112, the input end of the power conversion device 11 and the positive and negative DC buses, For the connection relationship between other parts and the working principle of the power conversion device 11, please refer to the description of the corresponding parts of the power conversion device 11 shown in Figure 4a, which will not be described again here.

Optionally, the power conversion device 11 can also be adapted to a three-level topology DC/AC converter. For details, please refer to the power conversion device shown in Figure 6b. As shown in Figure 6b, the output end of the power conversion device 11 also includes a third output end out _11N . Here, for the specific connection relationship of the third output end out _11N of the power conversion device 11, please refer to the power conversion device 11 shown in Figure 4b. The description of the corresponding parts will not be repeated here. It can be understood that the power conversion device 11 can be adapted not only to a two-level topology DC/AC converter, but also to a three-level topology DC/AC converter, and has strong applicability.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in parallel and connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, Each DC/DC conversion circuit only needs to compensate for the voltage difference between the bus voltage and the input voltage of the power conversion device 11, so that the input side voltage of each DC/DC conversion circuit in the power conversion device 11 is smaller, thereby Making the transmission power of the power conversion device 11 smaller can effectively reduce the power transmission loss of the power conversion device 11 , thereby improving the power transmission efficiency of the power conversion device 11 . In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. In addition, since the input side voltage of each DC/DC conversion circuit is small, the circuit cost of the above two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of the power conversion device 11 and having strong applicability.

For example, see FIG. 6c , which is another schematic structural diagram of the power conversion device provided by the present application. As shown in Figure 6c, compared with the power conversion device 11 shown in Figure 6a, the input end of the first DC/DC conversion circuit 111 and the second DC/DC conversion circuit 112 in the power conversion device 11 shown in Figure 6c The input terminals are connected in series.

Specifically, the first input terminal in ₁₁₊ of the power conversion device 11 is connected to the DC bus BUS1+ through the first output terminal out ₁₁₊ of the power conversion device 11, and the second input terminal in _11- of the power conversion device 11 is connected to the first The first input terminal in ₁₁₁₊ of the DC/DC conversion circuit 111. The second input terminal in ₁₁₁ - of the first DC/DC conversion circuit 111 is connected to the first input terminal in ₁₁₂₊ of the second DC/DC conversion circuit 112, and the second input terminal in _112- of the second DC/DC conversion circuit 112 The negative DC bus BUS1- is connected through the second output terminal out _11- of the power conversion device 11.

Optionally, the power conversion device 11 also includes a first switch K11. The first switch K11 is connected between the second input terminal in ₁₁ - of the power conversion device 11 and the second input terminal in 111 - of the second DC/DC conversion circuit _112. between.

Here, in the power conversion device 11 shown in FIG. 6c , except for the connection relationship between the input terminal of the first DC/DC conversion circuit 111 and the input terminal of the second DC/DC conversion circuit 112 and the connection relationship of the first switch K11 For specific connection relationships of other parts and the working principle of the power conversion device 11, please refer to the description of the corresponding parts of the power conversion device 11 shown in Figure 6a, and will not be described again here.

Optionally, the power conversion device 11 can also be adapted to a three-level topology DC/AC converter. For details, please refer to the power conversion device shown in Figure 6d. As shown in Figure 6d, the output end of the power conversion device 11 also includes a third output end out _11N . Here, for the specific connection relationship of the third output end out _11N of the power conversion device 11, please refer to the power conversion device 11 shown in Figure 4b. The description of the corresponding parts will not be repeated here. It can be understood that the power conversion device 11 can be adapted not only to a two-level topology DC/AC converter, but also to a three-level topology DC/AC converter, and has strong applicability.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, Compared with the structure in which the input terminals of two DC/DC converter circuits are connected in parallel, the input side voltage of each DC/DC converter circuit can be reduced to that of each DC/DC converter when the input terminals of two DC/DC converter circuits are connected in parallel. Half of the input side voltage of the circuit, that is, each DC/DC conversion circuit only needs to compensate half of the voltage difference between the bus voltage and the input terminal voltage of the power conversion device, so that each DC/DC converter in the power conversion device 11 The input side voltage of the circuit is smaller, so that the transmission power of the power conversion device 11 is smaller, which can reduce the power transmission loss of the power conversion device 11 to a greater extent, thereby improving the power transmission efficiency of the power conversion device 11 to a greater extent. In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. And since the input side voltage of each DC/DC converter circuit is reduced to half of the input side voltage of each DC/DC converter circuit when the input terminals of two DC/DC converter circuits are connected in parallel, therefore, each DC/DC converter Devices with lower withstand voltage can be selected in the circuit, which can further reduce the circuit cost of the above two DC/DC conversion circuits, thereby further reducing the circuit cost of the power conversion device 11 and improving the applicability.

For example, see FIG. 6e , which is another schematic structural diagram of the power conversion device provided by this application. As shown in Figure 6e, compared with the power conversion device 11 shown in Figure 6c, the number and position of switches in the power conversion device 11 shown in Figure 6e are different. Specifically, the power conversion device 11 includes a first switch K11 and a second switch K12. The first switch K11 is connected between the first input terminal in ₁₁₁₊ and the second input terminal in _111- of the first DC/DC conversion circuit 111. , the second switch K12 is connected between the first input terminal in ₁₁₂₊ and the second input terminal in _112- of the second DC/DC conversion circuit 112.

Here, in the power conversion device 11 shown in FIG. 6e, in addition to the input end of the first DC/DC conversion circuit 111, the input end of the second DC/DC conversion circuit 112, the input end of the power conversion device 11 and the positive and negative DC buses, For specific connection relationships of other parts besides the connection relationships between the power conversion devices 11 and the working principle of the power conversion device 11, please refer to the description of the corresponding parts of the power conversion device 11 shown in Figure 4e, which will not be described again here.

Optionally, the power conversion device 11 can also be adapted to a three-level topology DC/AC converter. For details, please refer to the power conversion device shown in Figure 6f. As shown in Figure 6f, the output end of the power conversion device 11 also includes a third output end out _11N . Here, for the specific connection relationship of the third output end out _11N of the power conversion device 11, please refer to the power conversion device 11 shown in Figure 4b. The description of the corresponding parts will not be repeated here. It can be understood that the power conversion device 11 can be adapted not only to a two-level topology DC/AC converter, but also to a three-level topology DC/AC converter, and has strong applicability.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, Compared with the structure in which the input terminals of two DC/DC converter circuits are connected in parallel, the input side voltage of each DC/DC converter circuit can be reduced to that of each DC/DC converter when the input terminals of two DC/DC converter circuits are connected in parallel. Half of the input side voltage of the circuit, that is, each DC/DC conversion circuit only needs to compensate half of the voltage difference between the bus voltage and the input terminal voltage of the power conversion device, so that each DC/DC converter in the power conversion device 11 The input side voltage of the circuit is smaller, so that the transmission power of the power conversion device 11 is smaller, which can reduce the power transmission loss of the power conversion device 11 to a greater extent, thereby improving the power transmission efficiency of the power conversion device 11 to a greater extent. In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. And since the input side voltage of each DC/DC converter circuit is reduced to half of the input side voltage of each DC/DC converter circuit when the input terminals of the two DC/DC converter circuits are connected in parallel, therefore, each DC/DC converter Devices with lower withstand voltage can be selected in the circuit, which can further reduce the circuit cost of the above two DC/DC conversion circuits, thereby further reducing the circuit cost of the power conversion device 11 and improving the applicability. Furthermore, when the input terminals of two DC/DC conversion circuits are connected in series, the number and positions of switches in the power conversion device 11 are diverse, so that the power conversion device 11 has diverse structures and high flexibility.

It should be noted that in the power conversion device 11 shown in Figures 3 to 6f, the positive DC bus BUS1+ and the negative DC bus BUS1- are located outside the power conversion device 11. The DC bus BUS1 - can also be located inside the power conversion device 11 .

Referring to Figure 7, Figure 7 is another schematic structural diagram of the power conversion device provided by the present application. As shown in Figure 7, compared with the power conversion device 11 shown in Figure 3, the power conversion device 11 shown in Figure 7 also includes a positive DC bus BUS1+, a negative DC bus BUS1- and a DC/AC converter. Specifically, the power conversion device 11 includes an input terminal, a first DC/DC conversion circuit 111, a second DC/DC conversion circuit 112, a positive DC bus BUS1+, a negative DC bus BUS1-, a DC/AC converter and an output terminal. The input terminal of the power conversion device 11 includes a first input terminal in ₁₁₊ and a second input terminal in _11- , and the output terminal of the power conversion device 11 includes a first output terminal out ₁₁₊ and a second output terminal out _11- . The input terminal of the DC/AC converter 21 includes a first input terminal in ₂₁₊ and a second input terminal in _21- .

After the input terminal in ₁₁₁ of the first DC/DC conversion circuit 111 is connected to the input terminal in ₁₁₂ of the second DC/DC conversion circuit 112, it is connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-. between. Specifically, the positive DC bus BUS1+ is connected to one end formed by connecting the input terminal in ₁₁₁ of the first DC/DC conversion circuit 111 and the input terminal in ₁₁₂ of the second DC/DC conversion circuit 112. The first DC/DC conversion circuit 111 The other end formed after the input terminal in ₁₁₁ is connected to the input terminal in ₁₁₂ of the second DC/DC conversion circuit 112 is connected to the first input terminal _in11+ of the power conversion device 11, and the second input terminal in _11- of the power conversion device 11 Connect the negative DC bus BUS1-.

The output end of the first DC/DC conversion circuit 111 and the output end of the second DC/DC conversion circuit 112 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, and the output end of the power conversion device 11 is connected to the DC/AC conversion The output end of the converter 21 and the input end of the DC/AC converter 21 are respectively connected to the positive DC bus BUS1+ and the negative DC bus BUS1-. Specifically, the positive DC bus BUS1+ is connected to the first output terminal out ₁₁₁₊ of the first DC/DC conversion circuit 111, and the second output terminal out _111- of the first DC/DC conversion circuit 111 is connected to the second DC/DC conversion circuit. The first output terminal out ₁₁₂₊ of 112 and the second output terminal out _112- of the second DC/DC conversion circuit 112 are connected to the negative DC bus BUS1-. The first output terminal out 11 ₊ of the power conversion device 11 is connected to the first output terminal out _{21 +} of the DC/AC converter 21 , and the second output terminal out _{11 −} of the power conversion device 11 is connected to the second output terminal out of the DC/AC converter 21 . The output terminal out _21- , the first input terminal in ₂₁₊ of the DC/AC converter 21 is connected to the positive DC bus BUS1+, and the second input terminal in _21- of the DC/AC converter 21 is connected to the negative DC bus BUS1-.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series with the input terminals of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, The two DC/DC conversion circuits only need to compensate for the voltage difference between the bus voltage and the input voltage of the power conversion device 11, so that the input side voltage of each DC/DC conversion circuit in the power conversion device 11 is smaller, thereby Making the transmission power of the power conversion device 11 smaller can effectively reduce the power transmission loss of the power conversion device 11 , thereby improving the power transmission efficiency of the power conversion device 11 . In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. In addition, since the input side voltage of each DC/DC conversion circuit is small, the circuit cost of the above two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of the power conversion device 11 and having strong applicability. In addition, the power conversion device 11 may also include a DC/AC converter, with various circuit structures and high flexibility.

For the convenience of description, the power conversion device 11 shown in FIG. 7 will be introduced in detail below by taking the DC power source as a battery cluster as an example.

For example, see FIG. 8a , which is another schematic structural diagram of the power conversion device provided by the present application. As shown in Figure 8a, compared with the power conversion device 11 shown in Figure 7, the input end of the first DC/DC conversion circuit 111 and the second DC/DC conversion circuit 112 in the power conversion device 11 shown in Figure 8a The input terminals are connected in parallel. Wherein, the input terminal of the first DC/DC conversion circuit 111 includes a first input terminal in ₁₁₁₊ and a second input terminal in _111- , and the input terminal of the second DC/DC conversion circuit 112 includes a first input terminal in ₁₁₂₊ and Second input terminal in _112- . The input terminal of the DC/AC converter 21 includes a first input terminal in ₂₁₊ and a second input terminal in _21- .

Specifically, the first input terminal in ₁₁₁₊ of the first DC/DC conversion circuit 111 is connected to the DC bus BUS1+. The first input terminal in ₁₁₁₊ of the first DC/DC conversion circuit 111 is also connected to the first input terminal in ₁₁₂₊ of the second DC/DC conversion circuit 112, and the second input terminal in _{111 of the first DC/DC conversion circuit 111 -Connect} the second input terminal in _112- of the second DC/DC conversion circuit 112. The second input terminal in _112- of the second DC/DC conversion circuit 112 is also connected to the first input terminal in ₁₁₊ of the power conversion device 11, and the second input terminal in _11- of the power conversion device 11 is connected to the negative DC bus BUS1-.

Optionally, the power conversion device 11 further includes a first switch K11, which is connected between the first input terminal in ₁₁₁₊ and the second input terminal in _111- of the first DC/DC conversion circuit 111.

Here, in the power conversion device 11 shown in FIG. 8a , except for the connection relationship between the input terminal of the first DC/DC conversion circuit 111 and the input terminal of the second DC/DC conversion circuit 112 and the connection relationship of the first switch K11 For specific connection relationships of other parts, please refer to the description of the corresponding parts in the power conversion device 11 shown in FIG. 7 , which will not be described again here. For the working principle of the power conversion device 11 shown in Figure 8a, please refer to the description of the corresponding parts of the power conversion device 11 shown in Figure 4a, and will not be described again here.

Optionally, the power conversion device 11 can also be adapted to a three-level topology DC/AC converter. For details, please refer to the power conversion device shown in Figure 8b. As shown in Figure 8b, the power conversion device 11 also includes a DC neutral line BUS1N, and the input end of the DC/AC converter 21 also includes a third input end in _21N . Among them, the third input terminal in _21N of the DC/AC converter 21 is connected to the second output terminal out _{111- of the first DC/DC conversion circuit 111} and the first output terminal of the second DC/DC conversion circuit 112 through the DC neutral line BUS1N. out ₁₁₂₊ connection. It can be understood that the power conversion device 11 can be adapted not only to a two-level topology DC/AC converter, but also to a three-level topology DC/AC converter, and has strong applicability.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in parallel and connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, Each DC/DC conversion circuit only needs to compensate for the voltage difference between the bus voltage and the input voltage of the power conversion device 11, so that the input side voltage of each DC/DC conversion circuit in the power conversion device 11 is smaller, thereby Making the transmission power of the power conversion device 11 smaller can effectively reduce the power transmission loss of the power conversion device 11 , thereby improving the power transmission efficiency of the power conversion device 11 . In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. In addition, since the input side voltage of each DC/DC conversion circuit is small, the circuit cost of the above two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of the power conversion device 11 and having strong applicability. In addition, the power conversion device 11 may also include a DC/AC converter, with various circuit structures and high flexibility.

For example, see FIG. 8c , which is another structural schematic diagram of the power conversion device provided by the present application. As shown in Figure 8c, compared with the power conversion device 11 shown in Figure 8a, the input end of the first DC/DC conversion circuit 111 and the second DC/DC conversion circuit 112 in the power conversion device 11 shown in Figure 8c The input terminals are connected in series.

Specifically, the first input terminal in ₁₁₁₊ of the first DC/DC conversion circuit 111 is connected to the DC bus BUS1+, and the second input terminal in _111- of the first DC/DC conversion circuit 111 is connected to the second DC/DC conversion circuit. The first input terminal in ₁₁₂₊ of 112 and the second input terminal in _112- of the second DC/DC conversion circuit 112 are connected to the first input terminal in ₁₁₊ of the power conversion device 11 and the second input terminal in of the power conversion device 11 _11- Connect the negative DC bus BUS1-.

Optionally, the power conversion device 11 also includes a first switch K11. The first switch K11 is connected between the first input terminal in ₁₁₊ of the power conversion device 11 and the first input terminal in 111+ of the first DC/DC conversion circuit ₁₁₁ . between.

Here, in the power conversion device 11 shown in FIG. 8c , except for the connection relationship between the input terminal of the first DC/DC conversion circuit 111 and the input terminal of the second DC/DC conversion circuit 112 and the connection relationship of the first switch K11 For specific connection relationships of other parts, please refer to the description of the corresponding parts of the power conversion device 11 shown in Figure 8a, and will not be described again here. For the working principle of the power conversion device 11 shown in Figure 8c, please refer to the description of the corresponding parts of the power conversion device 11 shown in Figure 4c, and will not be described again here.

Optionally, the power conversion device 11 can also be adapted to a three-level topology DC/AC converter. For details, please refer to the power conversion device shown in Figure 8d. As shown in Figure 8d, the power conversion device 11 also includes a DC neutral line BUS1N, and the input end of the DC/AC converter 21 also includes a third input end in _21N . Among them, the third input terminal in _21N of the DC/AC converter 21 is connected to the second output terminal out _{111- of the first DC/DC conversion circuit 111} and the first output terminal of the second DC/DC conversion circuit 112 through the DC neutral line BUS1N. out ₁₁₂₊ connection. It can be understood that the power conversion device 11 can be adapted not only to a two-level topology DC/AC converter, but also to a three-level topology DC/AC converter, and has strong applicability.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, Compared with the structure in which the input terminals of two DC/DC converter circuits are connected in parallel, the input side voltage of each DC/DC converter circuit can be reduced to that of each DC/DC converter when the input terminals of two DC/DC converter circuits are connected in parallel. Half of the input side voltage of the circuit, that is, each DC/DC conversion circuit only needs to compensate half of the voltage difference between the bus voltage and the input terminal voltage of the power conversion device, so that each DC/DC converter in the power conversion device 11 The input side voltage of the circuit is smaller, so that the transmission power of the power conversion device 11 is smaller, which can reduce the power transmission loss of the power conversion device 11 to a greater extent, thereby improving the power transmission efficiency of the power conversion device 11 to a greater extent. In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. And since the input side voltage of each DC/DC converter circuit is reduced to half of the input side voltage of each DC/DC converter circuit when the input terminals of two DC/DC converter circuits are connected in parallel, therefore, each DC/DC converter Devices with lower withstand voltage can be selected in the circuit, which can further reduce the circuit cost of the above two DC/DC conversion circuits, thereby further reducing the circuit cost of the power conversion device 11 and improving the applicability. Furthermore, the power conversion device 11 may also include a DC/AC converter, with various circuit structures and high flexibility.

For example, see FIG. 8e , which is another schematic structural diagram of the power conversion device provided by this application. As shown in Figure 8e, compared with the power conversion device 11 shown in Figure 8c, the number and position of switches in the power conversion device 11 shown in Figure 8e are different. Specifically, the power conversion device 11 includes a first switch K11 and a second switch K12. The first switch K11 is connected between the first input terminal in ₁₁₁₊ and the second input terminal in _111- of the first DC/DC conversion circuit 111. , the second switch K12 is connected between the first input terminal in ₁₁₂₊ and the second input terminal in _112- of the second DC/DC conversion circuit 112.

Here, for the specific connection relationships of other parts in the power conversion device 11 shown in FIG. 8e except for the switches, please refer to the description of the corresponding parts in the power conversion device 11 shown in FIG. 8c and will not be described again here. For the working principle of the power conversion device 11 shown in Figure 8e, please refer to the description of the corresponding parts of the power conversion device 11 shown in Figure 4e, and will not be described again here.

Optionally, the power conversion device 11 can also be adapted to a three-level topology DC/AC converter. For details, please refer to the power conversion device shown in Figure 8f. As shown in Figure 8f, the power conversion device 11 also includes a DC neutral line BUS1N, and the input end of the DC/AC converter 21 also includes a third input end in _21N . Among them, the third input terminal in _21N of the DC/AC converter 21 is connected to the second output terminal out _{111- of the first DC/DC conversion circuit 111} and the first output terminal of the second DC/DC conversion circuit 112 through the DC neutral line BUS1N. out ₁₁₂₊ connection. It can be understood that the power conversion device 11 can be adapted not only to a two-level topology DC/AC converter, but also to a three-level topology DC/AC converter, and has strong applicability.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, Compared with the structure in which the input terminals of two DC/DC converter circuits are connected in parallel, the input side voltage of each DC/DC converter circuit can be reduced to that of each DC/DC converter when the input terminals of two DC/DC converter circuits are connected in parallel. Half of the input side voltage of the circuit, that is, each DC/DC conversion circuit only needs to compensate half of the voltage difference between the bus voltage and the input terminal voltage of the power conversion device, so that each DC/DC converter in the power conversion device 11 The input side voltage of the circuit is smaller, so that the transmission power of the power conversion device 11 is smaller, which can reduce the power transmission loss of the power conversion device 11 to a greater extent, thereby improving the power transmission efficiency of the power conversion device 11 to a greater extent. In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. And since the input side voltage of each DC/DC converter circuit is reduced to half of the input side voltage of each DC/DC converter circuit when the input terminals of two DC/DC converter circuits are connected in parallel, therefore, each DC/DC converter Devices with lower withstand voltage can be selected in the circuit, which can further reduce the circuit cost of the above two DC/DC conversion circuits, thereby further reducing the circuit cost of the power conversion device 11 and improving the applicability. Furthermore, when the input ends of two DC/DC conversion circuits are connected in series, the number and positions of switches in the power conversion device 11 are diverse, so that the power conversion device 11 has diverse structures and high flexibility.

Referring to Figure 9, Figure 9 is another structural schematic diagram of the power conversion device provided by the present application. As shown in FIG. 9 , the power conversion device 11 has a symmetrical structure of the power conversion device 11 shown in FIG. 7 . Compared with the power conversion device 11 shown in FIG. 7 , the connection method of the input end of the power conversion device 11 shown in FIG. 9 is different. Specifically, the first input terminal in ₁₁₊ of the power conversion device 11 is connected to the DC bus BUS1+, and the second input terminal in _11- of the power conversion device 11 is connected to the input terminal in 111 of the first DC/DC conversion circuit 111 and the second input terminal in _11- of the power conversion device 11. One end formed by connecting the input terminals in ₁₁₂ of the two DC/DC converting circuits 112, and the other formed by connecting the input terminal in ₁₁₁ of the first DC/DC converting circuit 111 and the input terminal in _{112 of the second DC/DC converting circuit 112} . One end is connected to the negative DC bus BUS1-. Here, for the connection relationships of other parts of the power conversion device 11 except the connection relationship of the input terminals, please refer to the description of the corresponding parts of the power conversion device 11 shown in FIG. 7 , which will not be described again here.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series with the input terminals of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, The two DC/DC conversion circuits only need to compensate for the voltage difference between the bus voltage and the input voltage of the power conversion device 11, so that the input side voltage of each DC/DC conversion circuit in the power conversion device 11 is smaller, thereby Making the transmission power of the power conversion device 11 smaller can effectively reduce the power transmission loss of the power conversion device 11 , thereby improving the power transmission efficiency of the power conversion device 11 . In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. In addition, since the input side voltage of each DC/DC conversion circuit is small, the circuit cost of the two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of the power conversion device 11, and has strong applicability.

For the convenience of description, the power conversion device 11 shown in FIG. 9 will be introduced in detail below by taking the DC power source as a battery cluster as an example.

For example, see FIG. 10a , which is another structural schematic diagram of the power conversion device provided by the present application. As shown in Figure 10a, compared with the power conversion device 11 shown in Figure 9, the input end of the first DC/DC conversion circuit 111 and the second DC/DC conversion circuit 112 in the power conversion device 11 shown in Figure 10a The input terminals are connected in parallel. Wherein, the input terminal of the first DC/DC conversion circuit 111 includes a first input terminal in ₁₁₁₊ and a second input terminal in _111- , and the input terminal of the second DC/DC conversion circuit 112 includes a first input terminal in ₁₁₂₊ and Second input terminal in _112- . The input terminal of the DC/AC converter 21 includes a first input terminal in ₂₁₊ and a second input terminal in _21- .

Specifically, the first input terminal in ₁₁₊ of the power conversion device 11 is connected to the DC bus BUS1+, and the second input terminal in _11- of the power conversion device 11 is connected to the first input terminal in 111 of the first DC/DC conversion circuit _{111. +} . The first input terminal in ₁₁₁₊ of the first DC/DC conversion circuit 111 is also connected to the first input terminal in ₁₁₂₊ of the second DC/DC conversion circuit 112, and the second input terminal in _{111 of the first DC/DC conversion circuit 111 -Connect} the second input terminal in _112- of the second DC/DC conversion circuit 112. The second input terminal in _112- of the second DC/DC conversion circuit 112 is also connected to the negative DC bus BUS1-.

Optionally, the power conversion device 11 further includes a first switch K11, which is connected between the first input terminal in ₁₁₁₊ and the second input terminal in _111- of the first DC/DC conversion circuit 111.

Here, in the power conversion device 11 shown in FIG. 10 a , except for the connection relationship between the input terminal of the first DC/DC conversion circuit 111 and the input terminal of the second DC/DC conversion circuit 112 and the connection relationship of the first switch K11 For specific connection relationships of other parts, please refer to the description of the corresponding parts of the power conversion device 11 shown in FIG. 9 and will not be described again here. For the working principle of the power conversion device 11 shown in Figure 10a, please refer to the description of the corresponding parts of the power conversion device 11 shown in Figure 4a, and will not be described again here.

Optionally, the power conversion device 11 can also be adapted to a three-level topology DC/AC converter. For details, please refer to the power conversion device shown in Figure 10b. As shown in Figure 10b, the power conversion device 11 also includes a DC neutral line BUS1N, and the input end of the DC/AC converter 21 also includes a third input end in _21N . Among them, the third input terminal in _21N of the DC/AC converter 21 is connected to the second output terminal out _111- of the first DC/DC conversion circuit 111 and the first output terminal of the second DC/DC conversion circuit 112 through the DC neutral line BUS1N. out ₁₁₂₊ connection. It can be understood that the power conversion device 11 can be adapted not only to a two-level topology DC/AC converter, but also to a three-level topology DC/AC converter, and has strong applicability.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in parallel and connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, Each DC/DC conversion circuit only needs to compensate for the voltage difference between the bus voltage and the input voltage of the power conversion device 11, so that the input side voltage of each DC/DC conversion circuit in the power conversion device 11 is smaller, thereby Making the transmission power of the power conversion device 11 smaller can effectively reduce the power transmission loss of the power conversion device 11 , thereby improving the power transmission efficiency of the power conversion device 11 . In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. In addition, since the input side voltage of each DC/DC conversion circuit is small, the circuit cost of the above two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of the power conversion device 11 and having strong applicability. In addition, the power conversion device 11 may also include a DC/AC converter, with various circuit structures and high flexibility.

For example, see FIG. 10c , which is another schematic structural diagram of the power conversion device provided by this application. As shown in Figure 10c, compared with the power conversion device 11 shown in Figure 10a, the input end of the first DC/DC conversion circuit 111 and the second DC/DC conversion circuit 112 in the power conversion device 11 shown in Figure 10c The input terminals are connected in series.

Specifically, the first input terminal in ₁₁₊ of the power conversion device 11 is connected to the DC bus BUS1+, and the second input terminal in _11- of the power conversion device 11 is connected to the first input terminal in 111 of the first DC/DC conversion circuit _{111. +} . The second input terminal in _{111 -} of the first DC/DC conversion circuit 111 is connected to the first input terminal in ₁₁₂₊ of the second DC/DC conversion circuit 112 , and the second input terminal in _{112 - of the second DC/DC conversion circuit 112} Connect the negative DC bus BUS1-.

Optionally, the power conversion device 11 also includes a first switch K11. The first switch K11 is connected between the second input terminal in _11- of the power conversion device 11 and the second input terminal in 112- of the second DC/DC conversion circuit _112. between.

Here, in the power conversion device 11 shown in FIG. 10 c , except for the connection relationship between the input terminal of the first DC/DC conversion circuit 111 and the input terminal of the second DC/DC conversion circuit 112 and the connection relationship of the first switch K11 For specific connection relationships of other parts, please refer to the description of the corresponding parts of the power conversion device 11 shown in Figure 10a, and will not be described again here. For the working principle of the power conversion device 11 shown in Figure 10c, please refer to the description of the corresponding parts of the power conversion device 11 shown in Figure 4c, and will not be described again here.

Optionally, the power conversion device 11 can also be adapted to a three-level topology DC/AC converter. For details, please refer to the power conversion device shown in Figure 10d. As shown in Figure 10d, the power conversion device 11 also includes a DC neutral line BUS1N, and the input end of the DC/AC converter 21 also includes a third input end in _21N . Among them, the third input terminal in _21N of the DC/AC converter 21 is connected to the second output terminal out _111- of the first DC/DC conversion circuit 111 and the first output terminal of the second DC/DC conversion circuit 112 through the DC neutral line BUS1N. out ₁₁₂₊ connection. It can be understood that the power conversion device 11 can be adapted not only to a two-level topology DC/AC converter, but also to a three-level topology DC/AC converter, and has strong applicability.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, Compared with the structure in which the input terminals of two DC/DC converter circuits are connected in parallel, the input side voltage of each DC/DC converter circuit can be reduced to that of each DC/DC converter when the input terminals of two DC/DC converter circuits are connected in parallel. Half of the input side voltage of the circuit, that is, each DC/DC conversion circuit only needs to compensate half of the voltage difference between the bus voltage and the input terminal voltage of the power conversion device, so that each DC/DC converter in the power conversion device 11 The input side voltage of the circuit is smaller, so that the transmission power of the power conversion device 11 is smaller, which can reduce the power transmission loss of the power conversion device 11 to a greater extent, thereby improving the power transmission efficiency of the power conversion device 11 to a greater extent. In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. And since the input side voltage of each DC/DC converter circuit is reduced to half of the input side voltage of each DC/DC converter circuit when the input terminals of two DC/DC converter circuits are connected in parallel, therefore, each DC/DC converter Devices with lower withstand voltage can be selected in the circuit, which can further reduce the circuit cost of the above two DC/DC conversion circuits, thereby further reducing the circuit cost of the power conversion device 11 and improving the applicability. Furthermore, the power conversion device 11 may also include a DC/AC converter, with various circuit structures and high flexibility.

For example, see Figure 10e, which is another structural schematic diagram of the power conversion device provided by this application. As shown in Figure 10e, compared with the power conversion device 11 shown in Figure 10c, the number and position of switches in the power conversion device 11 shown in Figure 10e are different. Specifically, the power conversion device 11 includes a first switch K11 and a second switch K12. The first switch K11 is connected between the first input terminal in ₁₁₁₊ and the second input terminal in _111- of the first DC/DC conversion circuit 111. , the second switch K12 is connected between the first input terminal in ₁₁₂₊ and the second input terminal in _112- of the second DC/DC conversion circuit 112.

Here, for the specific connection relationships of other parts in the power conversion device 11 shown in FIG. 10e except for the switches, please refer to the description of the corresponding parts in the power conversion device 11 shown in FIG. 10c and will not be described again here. For the working principle of the power conversion device 11 shown in Figure 10e, please refer to the description of the corresponding parts of the power conversion device 11 shown in Figure 4e, and will not be described again here.

Optionally, the power conversion device 11 can also be adapted to a three-level topology DC/AC converter. For details, please refer to the power conversion device shown in Figure 10f. As shown in Figure 10f, the power conversion device 11 also includes a DC neutral line BUS1N, and the input end of the DC/AC converter 21 also includes a third input end in _21N . The third input terminal in _21N of the DC/AC converter 21 is connected to the second output terminal out _{111- of the first DC/DC conversion circuit 111} and the first output terminal of the second DC/DC conversion circuit 112 through the DC neutral line BUS1N. out ₁₁₂₊ connection. It can be understood that the power conversion device 11 can be adapted not only to a two-level topology DC/AC converter, but also to a three-level topology DC/AC converter, and has strong applicability.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series with the input terminal of the power conversion device 11 between the positive DC bus BUS1+ and the negative DC bus BUS1-, therefore, Compared with the structure in which the input terminals of two DC/DC converter circuits are connected in parallel, the input side voltage of each DC/DC converter circuit can be reduced to that of each DC/DC converter when the input terminals of two DC/DC converter circuits are connected in parallel. Half of the input side voltage of the circuit, that is, each DC/DC conversion circuit only needs to compensate half of the voltage difference between the bus voltage and the input terminal voltage of the power conversion device, so that each DC/DC converter in the power conversion device 11 The input side voltage of the circuit is smaller, so that the transmission power of the power conversion device 11 is smaller, which can reduce the power transmission loss of the power conversion device 11 to a greater extent, thereby improving the power transmission efficiency of the power conversion device 11 to a greater extent. In addition, the output terminals of the two DC/DC conversion circuits in the power conversion device 11 are connected in series between the positive DC bus BUS1+ and the negative DC bus BUS1-, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage. And since the input side voltage of each DC/DC converter circuit is reduced to half of the input side voltage of each DC/DC converter circuit when the input terminals of two DC/DC converter circuits are connected in parallel, therefore, each DC/DC converter Devices with lower withstand voltage can be selected in the circuit, which can further reduce the circuit cost of the above two DC/DC conversion circuits, thereby further reducing the circuit cost of the power conversion device 11 and improving the applicability. Furthermore, when the input ends of two DC/DC conversion circuits are connected in series, the number and positions of switches in the power conversion device 11 are diverse, so that the power conversion device 11 has diverse structures and high flexibility.

Based on the power conversion device 11 shown in Figures 3 to 6f, this application also provides a power supply system. For details, please refer to the power supply system 1 shown in Figures 11a to 12h. Refer to Figure 11a, which is a schematic structural diagram of the power supply system provided by this application. As shown in Fig. 11a, the power supply system 1 includes power conversion devices 11,..., power conversion device In, a DC/AC converter 21, and a positive DC bus BUS1+ and a negative DC bus BUS1- corresponding to the DC/AC converter 21. Among them, n is an integer greater than 1. The first input terminal in ₁₁₊ and the second input terminal in _11- of the power conversion device 11 are respectively connected to the positive and negative poles of the DC power supply 31, and the first output terminal out ₁₁₊ and the second output terminal out _{11- of} the power conversion device 11 are connected. The positive DC bus BUS1+ and the negative DC bus BUS1- are respectively connected; ...; the first input terminal in _1n+ and the second input terminal in _1n- of the power conversion device 1n are respectively connected to the positive and negative poles of the DC power supply 3n, and the power conversion device 1n The first output terminal out _1n+ and the second output terminal out _1n- are respectively connected to the positive DC bus BUS1+ and the negative DC bus BUS1-. The first input terminal in ₂₁₊ and the second input terminal in _21- of the DC/AC converter 21 are connected to the positive DC bus BUS1+ and the negative DC bus BUS1- respectively, and the output terminal of the DC/AC converter 21 is connected to the AC power grid.

Optionally, the power supply system 1 shown in Figure 11a also includes a DC neutral line corresponding to the DC/AC converter 21. For details, please refer to the power supply system 1 shown in Figure 11b. As shown in Figure 11b, the power supply system 1 also includes a DC neutral line BUS1N corresponding to the DC/AC converter 21. The output end of the power conversion device 11 also includes a third output end out _11N , ..., and the output end of the power conversion device 1n also includes a third output end out _1nN . The input terminal of the DC/AC converter 21 also includes a third input terminal in _21N . Among them, the third output terminal out _11N , ... of the power conversion device 11, the third output terminal out _1nN of the power conversion device 1n, and the third input terminal in _21N of the DC/AC converter 21 are all connected to the DC neutral line BUS1N.

The power supply system 1 shown in Figure 11a and Figure 11b takes one DC/AC converter as an example. The number of DC/AC converters in the power supply system 1 can also be multiple. For details, please refer to Figure 11c and Figure 11d. The power supply system shown is 1. As shown in Figure 11c, Figure 11c is a schematic structural diagram of the power supply system provided by this application. As shown in Figure 11c, the power supply system 1 includes power conversion devices 11,..., power conversion devices 1n, DC/AC converters 21,..., DC/AC converters 2n, and DC/AC converters 21 corresponding to the positive DC The bus BUS1+ and the negative DC bus BUS1-, ..., and the positive DC bus BUSn+ and the negative DC bus BUSn- corresponding to the DC/AC converter 2n. Among them, n is an integer greater than 1. The first input terminal in ₁₁₊ and the second input terminal in _11- of the power conversion device 11 are respectively connected to the positive and negative poles of the DC power supply 31, and the first output terminal out ₁₁₊ of the power conversion device 11 is connected to DC/ through the positive DC bus BUS1+. The first input terminal in ₂₁₊ of the AC converter 21 and the second output terminal out _11- of the power conversion device 11 are connected to the second input terminal in 21- of the DC/AC converter 21 through the negative DC bus BUS1 _- ;...; The first input terminal in _1n+ and the second input terminal in _1n- of the power conversion device 1n are respectively connected to the positive and negative poles of the DC power supply 3n, and the first output terminal out _1n+ of the power conversion device 1n is connected to the DC/AC conversion through the positive DC bus BUSn+. The first input terminal in _2n+ of the converter 2n and the second output terminal out _1n- of the power conversion device 1n are connected to the second input terminal in _2n- of the DC/AC converter 2n through the negative DC bus BUSn-. The output terminals of the DC/AC converter 21, ..., and the output terminal of the DC/AC converter 2n are all connected to the AC power grid.

Optionally, the power supply system 1 shown in Figure 11c also includes a DC neutral line corresponding to each of the n DC/AC converters. For details, please refer to the power supply system 1 shown in Figure 11d. As shown in Figure 11d, the power supply system 1 also includes DC neutral lines BUS1N corresponding to the DC/AC converter 21, ..., and DC neutral lines BUSnN corresponding to the DC/AC converter 2n. The output end of the power conversion device 11 also includes a third output end out _11N , ..., and the output end of the power conversion device 1n also includes a third output end out _1nN . The input terminal of the DC/AC converter 21 also includes a third input terminal in _21N , ..., and the input terminal of the DC/AC converter 2n further includes a third input terminal in _2nN . Among them, the third input terminal in _21N of the DC/AC converter 21 is connected to the DC neutral line BUS1N and is connected to the third output terminal out _11N of the power conversion device 11; ...; the third input terminal in _2nN of the DC/AC converter 2n is connected to the DC The neutral line BUSnN is connected to the third output terminal out _1nN of the power conversion device 1n.

It should be noted that when the DC power supply connected to the input terminals of the n power conversion devices is a battery cluster, any one of the n power conversion devices is a DC/DC converter or a DC/AC converter. 21 is PCS, and the power supply system 1 is an energy storage system. The energy storage system also includes a battery cluster connected to the input end of each power conversion device; when the DC power supply connected to the input end of the above n power conversion devices is a photovoltaic group In series mode, the power conversion device 11 is a photovoltaic optimizer, the DC/AC converter 21 is a photovoltaic inverter, and the power supply system 1 is a photovoltaic power supply system. For the convenience of description, the power supply system 1 shown in FIGS. 11 a to 11 d is introduced below by taking the DC power source as a battery cluster as an example.

Any power conversion device in the power supply system 1 shown in Figure 11a may be any of the power conversion devices 11 shown in Figures 3, 4a, 4c, 4e, 5, 6a, 6c and 6e. A power conversion device 11. For example, any power conversion device in the power supply system 1 shown in Figure 11a is the power conversion device shown in Figure 4a. For details, please refer to Figure 12a. As shown in Figure 12a, the power supply system 1 includes a power conversion device 11,..., a power conversion device 1n, a DC/AC converter 21, a positive DC bus BUS1+ and a negative DC bus BUS1- corresponding to the DC/AC converter 21, and a battery. Clusters 31, ..., and battery cluster 3n, n is an integer greater than 1. Here, for the connection relationship between each device and each DC bus in the power supply system 1, please refer to the description of the corresponding part in the power supply system 1 shown in Figure 11a, and will not be described again here. For example, any power conversion device in the power supply system 1 shown in Figure 11a is the power conversion device shown in Figure 4c. For details, please refer to Figure 12b, and the description will not be further elaborated here.

Any power conversion device in the power supply system 1 shown in Fig. 11b may be any power conversion device 11 among the power conversion devices 11 shown in Fig. 4b, Fig. 4d, Fig. 4f, Fig. 6b, Fig. 6d and Fig. 6f. For example, any power conversion device in the power supply system 1 shown in Figure 11b is the power conversion device shown in Figure 4b. For details, see Figure 12c. As shown in Figure 12c, compared with the power supply system 1 shown in Figure 12a, the power supply system 1 shown in Figure 12c also includes a DC neutral line BUS1N corresponding to the DC/AC converter 21. Here, for the connection relationship between each device and each DC bus in the power supply system 1, please refer to the description of the corresponding part in the power supply system 1 shown in Figure 11b, and will not be described again here. For example, any power conversion device in the power supply system 1 shown in Figure 11b is the power conversion device shown in Figure 4d. For details, please refer to Figure 12d, and the description will not be further elaborated here.

Any power conversion device in the power supply system 1 shown in Fig. 11c may be any power conversion device 11 shown in Fig. 3, Fig. 4a, Fig. 4c, Fig. 4e, Fig. 5, Fig. 6a, Fig. 6c and Fig. 6e. A power conversion device 11. For example, any power conversion device in the power supply system 1 shown in Figure 11c is the power conversion device shown in Figure 4a. For details, see Figure 12e. As shown in Figure 12e, the power supply system 1 includes power conversion devices 11,..., power conversion devices 1n, DC/AC converters 21,..., DC/AC converters 2n, and DC/AC converters 21 corresponding to The bus BUS1+ and the negative DC bus BUS1-, ..., the DC/AC converter 2n correspond to the positive DC bus BUSn+ and the negative DC bus BUSn-, the battery cluster 31, ..., and the battery cluster 3n, n is an integer greater than 1. Here, for the connection relationship between each device and each DC bus in the power supply system 1, please refer to the description of the corresponding part in the power supply system 1 shown in Figure 11c, and will not be described again here. For example, any power conversion device in the power supply system 1 shown in Figure 11c is the power conversion device shown in Figure 4c. For details, please refer to Figure 12f, and the description will not be further elaborated here.

Any power conversion device in the power supply system 1 shown in Fig. 11d may be any power conversion device 11 among the power conversion devices 11 shown in Fig. 4b, Fig. 4d, Fig. 4f, Fig. 6b, Fig. 6d and Fig. 6f. For example, any power conversion device in the power supply system 1 shown in Figure 11d is the power conversion device shown in Figure 4b. For details, see Figure 12g. As shown in Figure 12g, compared with the power supply system 1 shown in Figure 12e, the power supply system 1 shown in Figure 12g also includes DC neutral lines BUS1N corresponding to the DC/AC converter 21,..., DC/AC converter 2n corresponding The DC neutral line BUSnN. Here, for the connection relationship between each device and each DC bus in the power supply system 1, please refer to the description of the corresponding part in the power supply system 1 shown in Figure 11d, and will not be described again here. For example, any power conversion device in the power supply system 1 shown in Figure 11d is the power conversion device shown in Figure 4d. For details, please refer to Figure 12h, and the description will not be further elaborated here.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in each power conversion device in the power supply system 1 are connected in series or in parallel, their input terminals are connected in series between the positive DC bus and the negative DC bus. Therefore, each The two DC/DC conversion circuits of each power conversion device only need to compensate for the voltage difference between the bus voltage and the input terminal voltage of the power conversion device where they are located, so that each DC/DC conversion circuit in each power conversion device The input side voltage is smaller, so that the transmission power of each power conversion device is smaller, which can effectively reduce the power transmission loss of each power conversion device, thereby improving the power transmission efficiency of each power conversion device to improve the power supply system 1 power transfer efficiency. In addition, the output terminals of the two DC/DC conversion circuits in each power conversion device are connected in series between the positive DC bus and the negative DC bus, so that the output side voltage of each DC/DC conversion circuit is smaller than the bus voltage, and because The input side voltage of each DC/DC conversion circuit is small, so the circuit cost of the above two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of each power conversion device, thereby reducing the circuit cost of the power supply system 1, Strong applicability.

Based on the power conversion device 11 shown in Figures 7 to 10f, this application also provides a power supply system. For details, please refer to the power supply system 1 shown in Figures 13 and 14. Referring to Figure 13, Figure 13 is another structural schematic diagram of the power supply system provided by this application. As shown in FIG. 13 , the power supply system 1 includes power conversion devices 11 , . . . , and a power conversion device 1 n , where n is an integer greater than 1. Among them, the first input terminal in ₁₁₊ and the second input terminal in _11- of the power conversion device 11 are respectively connected to the positive and negative poles of the DC power supply 31, ..., and the first input terminal in _1n+ and the second input terminal of the power conversion device 1n Terminal in _1n- is connected to the positive and negative poles of DC power supply 3n respectively. The output terminals of the power conversion device 11, ..., and the output terminals of the power conversion device 1n are all connected to the AC power grid. Any power conversion device among the n power conversion devices mentioned above may be any power conversion device 11 among the power conversion devices 11 shown in FIGS. 7 to 10 f.

It should be noted that when the DC power supply connected to the input terminals of the n power conversion devices is a battery cluster, any one of the n power conversion devices is a PCS, and the power supply system 1 is an energy storage system. The energy storage system also includes a battery cluster connected to the input end of each power conversion device; when the DC power supply connected to the input ends of the n power conversion devices is a photovoltaic string, the power conversion device 11 is a photovoltaic inverter, Power supply system 1 is a photovoltaic power supply system. For example, the power supply system 1 shown in Figure 13 is an energy storage system, and any power conversion device in the power supply system 1 is the power conversion device shown in Figure 8b. For details, please refer to Figure 14, and the description will not be repeated here.

In the embodiment of the present application, since the input terminals of the two DC/DC conversion circuits in each power conversion device in the power supply system 1 are connected in series or in parallel, their input terminals are connected in series between the positive DC bus and the negative DC bus. Therefore, each The two DC/DC conversion circuits of each power conversion device only need to compensate for the voltage difference between the bus voltage and the input terminal voltage of the respective power conversion device, so that each DC/DC conversion circuit in each power conversion device The input side voltage is smaller, so that the transmission power of each power conversion device is smaller, which can effectively reduce the power transmission loss of each power conversion device, thereby improving the power transmission efficiency of each power conversion device to improve the power supply system 1 power transfer efficiency. In addition, the output terminals of the two DC/DC conversion circuits in each power conversion device are connected in series between the positive DC bus and the negative DC bus, so that the output side voltage of each DC/DC conversion circuit in each power conversion device can be equalized. Less than the bus voltage, and because the input side voltage of each DC/DC conversion circuit is small, the circuit cost of the above two DC/DC conversion circuits can be effectively reduced, thereby reducing the circuit cost of each power conversion device to reduce power supply System 1 has low circuit cost and strong applicability. In addition, the power conversion device has various circuit structures, making the power supply system 1 have diverse structures and high flexibility.

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of changes or replacements within the technical scope disclosed in the present application, and all of them should be covered. within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims (26)

1. A power conversion device, characterized in that the power conversion device includes an input end, a first DC/DC conversion circuit, a second DC/DC conversion circuit and an output end, wherein: After the input end of the first DC/DC conversion circuit and the input end of the second DC/DC conversion circuit are connected, they are connected in series with the input end of the power conversion device between the positive DC bus and the negative DC bus, so The positive DC bus and the negative DC bus are used to connect the input end of the DC/AC converter; The output end of the first DC/DC conversion circuit and the output end of the second DC/DC conversion circuit are connected in series between the positive DC bus and the negative DC bus; The output ends of the power conversion device are respectively connected to the positive DC bus and the negative DC bus. 2. The power conversion device according to claim 1, characterized in that, after the input end of the first DC/DC conversion circuit and the input end of the second DC/DC conversion circuit are connected in parallel, they are connected with the power conversion device. The input terminal of the device is connected in series between the positive DC bus and the negative DC bus. 3. The power conversion device according to claim 2, characterized in that the input terminal of the first DC/DC conversion circuit includes a first input terminal and a second input terminal, and the input terminal of the second DC/DC conversion circuit The input terminal includes a first input terminal and a second input terminal, and the input terminal of the power conversion device includes a first input terminal and a second input terminal, wherein: The first input end of the first DC/DC conversion circuit is connected to the positive DC bus and the first input end of the second DC/DC conversion circuit, and the second input end of the first DC/DC conversion circuit The second input terminal of the second DC/DC conversion circuit is connected to the first input terminal of the power conversion device, and the second input terminal of the power conversion device is connected to the negative DC bus. 4. The power conversion device according to claim 2, wherein the input terminal of the first DC/DC conversion circuit includes a first input terminal and a second input terminal, and the input terminal of the second DC/DC conversion circuit The input terminal includes a first input terminal and a second input terminal, and the input terminal of the power conversion device includes a first input terminal and a second input terminal, wherein: The first input end of the power conversion device is connected to the positive DC bus, and the second input end of the power conversion device is connected to the first input end of the first DC/DC conversion circuit and the second DC/DC The first input terminal of the conversion circuit and the second input terminal of the first DC/DC conversion circuit are connected to the second input terminal of the second DC/DC conversion circuit and the negative DC bus. 5. The power conversion device according to any one of claims 2 to 4, characterized in that the power conversion device further includes a controller; The controller is used to control the input terminal voltage of the first DC/DC conversion circuit or the input terminal voltage of the second DC/DC conversion circuit to reach a first voltage, where the first voltage is a bus voltage and the power The difference between the input terminal voltages of the conversion device, the bus voltage is the voltage between the positive DC bus and the negative DC bus. 6. The power conversion device according to any one of claims 2 to 4, characterized in that the power conversion device further includes a first switch and a controller, and the input end of the first DC/DC conversion circuit includes a third An input terminal and a second input terminal, the first switch is connected between the first input terminal and the second input terminal of the first DC/DC conversion circuit; The controller is configured to control the first switch to close when the input voltage of the power conversion device is greater than or equal to a preset voltage threshold; The controller is also used to control the first switch to turn off and control the input of the first DC/DC conversion circuit when the input voltage of the power conversion device is less than the preset voltage threshold. The terminal voltage or the input terminal voltage of the second DC/DC conversion circuit reaches a first voltage. The first voltage is the difference between the bus voltage and the input terminal voltage of the power conversion device. The bus voltage is The voltage between the positive DC bus and the negative DC bus. 7. The power conversion device according to claim 1, characterized in that, after the input end of the first DC/DC conversion circuit and the input end of the second DC/DC circuit are connected in series, they are connected to the power conversion device. The input terminal of is connected in series between the positive DC bus and the negative DC bus. 8. The power conversion device according to claim 7, wherein the input terminal of the first DC/DC conversion circuit includes a first input terminal and a second input terminal, and the input terminal of the second DC/DC conversion circuit The input terminal includes a first input terminal and a second input terminal, and the input terminal of the power conversion device includes a first input terminal and a second input terminal, wherein: The first input end of the first DC/DC conversion circuit is connected to the positive DC bus, and the second input end of the first DC/DC conversion circuit is connected to the first input end of the second DC/DC circuit, The second input terminal of the second DC/DC conversion circuit is connected to the first input terminal of the power conversion device, and the second input terminal of the power conversion device is connected to the negative DC bus. 9. The power conversion device according to claim 8, characterized in that the power conversion device further includes a first switch and a controller, the first switch is connected to the first node of the first DC/DC conversion circuit. Between the input end and the first input end of the power conversion device; The controller is configured to control the first switch to close when the input voltage of the power conversion device is greater than or equal to a preset voltage threshold; The controller is also used to control the first switch to turn off and control the input of the first DC/DC conversion circuit when the input voltage of the power conversion device is less than the preset voltage threshold. The sum of the terminal voltage and the input terminal voltage of the second DC/DC conversion circuit reaches a first voltage, and the first voltage is the difference between the bus voltage and the input terminal voltage of the power conversion device. The bus The voltage is the voltage between the positive DC bus and the negative DC bus. 10. The power conversion device according to claim 7, wherein the input terminal of the first DC/DC conversion circuit includes a first input terminal and a second input terminal, and the input terminal of the second DC/DC conversion circuit The input terminal includes a first input terminal and a second input terminal, and the input terminal of the power conversion device includes a first input terminal and a second input terminal, wherein: The first input end of the power conversion device is connected to the positive DC bus, and the second input end of the power conversion device is connected to the first input end of the first DC/DC conversion circuit. The first DC/DC The second input end of the conversion circuit is connected to the first input end of the second DC/DC conversion circuit, and the second input end of the second DC/DC conversion circuit is connected to the negative DC bus. 11. The power conversion device according to claim 10, characterized in that the power conversion device further includes a first switch and a controller, the first switch is connected between the second input end of the power conversion device and the between the second input terminals of the second DC/DC conversion circuit; The controller is configured to control the first switch to close when the input voltage of the power conversion device is greater than or equal to a preset voltage threshold; The controller is also used to control the first switch to turn off and control the input of the first DC/DC conversion circuit when the input voltage of the power conversion device is less than the preset voltage threshold. The sum of the terminal voltage and the input terminal voltage of the second DC/DC conversion circuit reaches a first voltage, and the first voltage is the difference between the bus voltage and the input terminal voltage of the power conversion device. The bus The voltage is the voltage between the positive DC bus and the negative DC bus. 12. The power conversion device according to claim 8 or 10, characterized in that the power conversion device further includes a first switch, a second switch and a controller, the first switch is connected to the first DC/ Between the first input terminal and the second input terminal of the DC conversion circuit, the second switch is connected between the first input terminal and the second input terminal of the second DC/DC conversion circuit; The controller is configured to control both the first switch and the second switch to close when the input voltage of the power conversion device is greater than or equal to a preset voltage threshold; The controller is also configured to control both the first switch and the second switch to turn off when the input voltage of the power conversion device is less than the preset voltage threshold, and control the first switch to turn off. The sum of the input terminal voltage of the DC/DC conversion circuit and the input terminal voltage of the second DC/DC conversion circuit reaches a first voltage, and the first voltage is between the bus voltage and the input terminal voltage of the power conversion device The bus voltage is the voltage between the positive DC bus and the negative DC bus. 13. The power conversion device according to claim 7, 8 or 10, characterized in that the power conversion device further includes a controller; The controller is used to control the sum of the input terminal voltage of the first DC/DC conversion circuit and the input terminal voltage of the second DC/DC conversion circuit to reach a first voltage, where the first voltage is the sum of the bus voltage and the input terminal voltage of the second DC/DC conversion circuit. The difference between the input terminal voltages of the power conversion device, the bus voltage is the voltage between the positive DC bus and the negative DC bus. 14. The power conversion device according to any one of claims 1 to 13, characterized in that the power conversion device includes a controller, wherein: The controller is configured to adjust the first DC/DC converter when there is a deviation between the first output voltage of the first DC/DC converter circuit and the second output voltage of the second DC/DC converter circuit. The power of the DC conversion circuit and/or the power of the second DC/DC conversion circuit is such that the difference between the first output voltage and the second output voltage is reduced. 15. The power conversion device according to any one of claims 1 to 14, characterized in that the power conversion device further includes the DC/AC converter, the positive DC bus and the negative DC bus, wherein , the output end of the power conversion device is connected to the output end of the DC/AC converter, and the input end of the DC/AC converter is respectively connected to the positive DC bus and the negative DC bus. 16. The power conversion device according to claim 15, wherein the input terminal of the DC/AC converter includes a first input terminal and a second input terminal, wherein the first input terminal of the DC/AC converter The input terminal and the second input terminal are respectively connected to the positive DC bus and the negative DC bus. 17. The power conversion device according to claim 16, wherein the power conversion device further includes a DC neutral line, and the input end of the DC/AC converter further includes a third input end, wherein the DC/ The third input terminal of the AC converter is connected to the series connection point of the output terminal of the first DC/DC conversion circuit and the output terminal of the second DC/DC conversion circuit through the DC neutral line. 18. A power supply system, characterized in that the power supply system includes n power conversion devices as claimed in any one of claims 15 to 17, and the input end of each power conversion device is used to connect a DC power supply. , the output end of the power conversion device is used to connect to the AC power grid or load, and n is an integer greater than 1. 19. The power supply system according to claim 18, characterized in that the DC power supply is a battery cluster, the power supply system further includes the n battery clusters, and the n battery clusters are respectively connected to the n power supplies. The input terminal of the conversion device. 20. A power supply system, characterized in that the power supply system includes a DC/AC converter, a positive DC bus and a negative DC bus corresponding to the DC/AC converter, and n as claimed in any one of claims 1 to 14 The power conversion device according to item 1, wherein the input end of each power conversion device is used to connect a DC power supply, and the positive DC bus and the negative DC bus are connected to the input end of the DC/AC converter, The output end of the DC/AC converter is used to connect to the AC power grid or load, and n is an integer greater than 1. 21. The power supply system according to claim 20, wherein the output end of the power conversion device includes a first output end and a second output end, and the input end of the DC/AC converter includes a first input end. and the second input terminal, where: The first output end and the second output end of the power conversion device are respectively connected to the positive DC bus and the negative DC bus, and the first input end and the second input end of the DC/AC converter are respectively connected to the the positive DC bus and the negative DC bus. 22. The power supply system according to claim 21, wherein the power supply system further includes a DC neutral line corresponding to the DC/AC converter, and the output end of the power conversion device further includes a third output end. The input terminal of the DC/AC converter also includes a third input terminal, wherein: The third output end of the power conversion device is connected to the series connection between the output end of the first DC/DC conversion circuit and the output end of the second DC/DC conversion circuit; The third output terminal of the power conversion device and the third input terminal of the DC/AC converter are both connected to the DC neutral line. 23. The power supply system according to claim 20, characterized in that the number of the DC/AC converters is the n, and the n DC/AC converters correspond to n positive DC buses and n negative DC bus, the n DC/AC converters correspond to the n positive DC buses, the n DC/AC converters correspond to the n negative DC buses, the n DC /AC converters correspond to the n power conversion devices one-to-one, and the input end of each DC/AC converter in the n DC/AC converters is respectively connected to the corresponding upright terminal of each DC/AC converter. current bus and negative DC bus. 24. The power supply system according to claim 23, wherein the output end of the power conversion device includes a first output end and a second output end, and the input end of each DC/AC converter includes a first input and second input, where: The first input end of each DC/AC converter is connected to the first output end of the power conversion device corresponding to each DC/AC converter through the corresponding positive DC bus of each DC/AC converter, The second input end of each DC/AC converter is connected to the second output end of the power conversion device corresponding to each DC/AC converter through the corresponding negative DC bus of each DC/AC converter. 25. The power supply system according to claim 24, characterized in that the power supply system further includes n DC neutral lines corresponding to the n DC/AC converters, and the output end of the power conversion device further includes a third Output terminal, the input terminal of each DC/AC converter also includes a third input terminal, wherein: The third output end of the power conversion device is connected to the series connection between the output end of the first DC/DC conversion circuit and the output end of the second DC/DC conversion circuit; The third input end of each DC/AC converter is connected to the third output end of the power conversion device corresponding to each DC/AC converter through the DC neutral line corresponding to each DC/AC converter, so The n DC/AC converters correspond to the n DC neutral lines one-to-one. 26. The power supply system according to any one of claims 20 to 25, characterized in that the DC power supply is a battery cluster, the power supply system further includes the n battery clusters, and the n battery clusters are respectively connected The input terminals of the n power conversion devices.