CN114156966B - Multi-stage power conversion circuit voltage stabilization method and device, power conversion system - Google Patents

Abstract

The present invention provides a voltage stabilization method and device for a multi-stage power conversion circuit, and a power conversion system. The method is applied to a multi-stage power conversion circuit; the multi-stage power conversion circuit includes at least two stages of power conversion circuits connected in series, one side of the at least two stages of power conversion circuits connected in series is connected to an energy storage device, and the other side is connected to an external power supply, and the external power supply is a DC source or an AC source; the method includes: obtaining the required voltage of the energy storage device and the current flow direction of the multi-stage power conversion circuit; determining the voltage stabilization points of each stage of the power conversion circuit and the voltage stabilization sequence of each stage of the power conversion circuit according to the current flow direction; determining the voltage reference value corresponding to each voltage stabilization point according to the required voltage and current flow direction; and performing voltage stabilization control on each stage of the power conversion circuit based on the voltage reference value corresponding to each voltage stabilization point and the voltage stabilization sequence of each stage of the power conversion circuit. The present invention can support voltage stabilization control of multi-stage power conversion circuits under a wide voltage range.

Description

Multi-stage power conversion circuit voltage stabilization method and device, power conversion system

Technical Field

The present invention belongs to the technical field of circuit control, and more specifically, relates to a voltage stabilizing method and device for a multi-stage power conversion circuit, and a power conversion system.

Background Art

The voltage stabilization control of the multi-stage power conversion circuit is an important link to ensure the stable operation of the entire multi-stage power conversion circuit. In the prior art, in order to broaden the voltage range of the multi-stage power conversion circuit, the prior art may adopt a multi-stage power conversion circuit. At this time, the voltage stabilization scheme for the single-stage power conversion circuit in the prior art is no longer applicable.

Summary of the invention

The object of the present invention is to provide a voltage stabilization method and device for a multi-stage power conversion circuit, and a power conversion system, so as to realize voltage stabilization control of the multi-stage power conversion circuit under a wide voltage range.

To achieve the above object, the technical solution adopted by the present invention is to provide a multi-stage power conversion circuit voltage stabilization method, the method is applied to the multi-stage power conversion circuit; the multi-stage power conversion circuit includes at least two stages of power conversion circuits connected in series, one side of the at least two stages of power conversion circuits connected in series is used to connect to an energy storage device, and the other side is used to connect to an external power supply, wherein the external power supply is a DC source or an AC source; the method includes:

Obtaining the required voltage of the energy storage device and the current flow direction of the multi-stage power conversion circuit;

Determining the voltage stabilization points of each level of the power conversion circuit and the voltage stabilization sequence of each level of the power conversion circuit according to the current flow direction of the multi-level power conversion circuit;

Determining a voltage reference value corresponding to each voltage stabilization point according to the required voltage and the current flow direction of the multi-stage power conversion circuit;

The voltage stabilization control is performed on each level of the power conversion circuit based on the voltage reference value corresponding to each voltage stabilization point and the voltage stabilization sequence of each level of the power conversion circuit.

In a possible implementation, determining the voltage reference value corresponding to each voltage stabilization point according to the required voltage and the current flow direction of the multi-stage power conversion circuit includes:

If the current flow direction of the multi-stage power conversion circuit is the first direction, the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit and the voltage reference value corresponding to the voltage stabilization point of the final power conversion circuit are determined according to the required voltage, and the voltage reference value corresponding to the voltage stabilization point of each intermediate power conversion circuit is determined according to the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit and the preset voltage difference between adjacent power conversion circuits at each stage;

Among them, the current flow direction is the first direction, which means that the current flows from the energy storage device to the external power supply, the primary power conversion circuit is the first-stage power conversion circuit starting from the energy storage device, the final-stage power conversion circuit is the last-stage power conversion circuit starting from the energy storage device, and the intermediate power conversion circuits are other power conversion circuits except the primary power conversion circuit and the final-stage power conversion circuit.

In a possible implementation, the step of determining, according to the required voltage, a voltage reference value corresponding to a voltage stabilization point of a primary power conversion circuit and a voltage reference value corresponding to a voltage stabilization point of a final power conversion circuit includes:

Determine the range to which the required voltage belongs;

The voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit and the voltage reference value corresponding to the voltage stabilization point of the final power conversion circuit are determined according to the range to which the required voltage belongs and various preset reference values corresponding to the range.

In a possible implementation, a method for determining a preset voltage difference between adjacent power conversion circuits of each level is as follows:

Obtaining a voltage boost ratio of the multi-stage power conversion circuit;

The preset voltage difference between adjacent power conversion circuits of each level is determined according to the boost ratio.

In a possible implementation, determining the voltage reference value corresponding to each voltage stabilization point according to the required voltage and the current flow direction of the multi-stage power conversion circuit includes:

If the current flow direction of the multi-stage power conversion circuit is the second direction, a preset charging voltage of the energy storage device is obtained, a voltage reference value corresponding to a voltage stabilization point of the primary power conversion circuit is determined according to the preset charging voltage, and voltage reference values corresponding to voltage stabilization points of the final power conversion circuit and intermediate power conversion circuits are determined according to the required voltage;

Among them, the current flowing in the second direction means that the current flows from the external power supply to the energy storage device, the primary power conversion circuit is the first-stage power conversion circuit starting from the energy storage device, the final-stage power conversion circuit is the last-stage power conversion circuit starting from the energy storage device, and the intermediate power conversion circuits are other power conversion circuits except the primary power conversion circuit and the final-stage power conversion circuit.

In a possible implementation, the step of determining voltage reference values corresponding to voltage stabilization points of the final power conversion circuit and intermediate power conversion circuits according to the required voltage includes:

Determine the range to which the required voltage belongs;

The voltage reference values corresponding to the voltage stabilization points of the final power conversion circuit and the intermediate power conversion circuits are determined according to the range to which the required voltage belongs and various preset reference values corresponding to the range.

In a possible implementation, determining a voltage stabilization sequence of each level of the power conversion circuit according to the current flow direction of the multi-level power conversion circuit includes:

If the current flow direction of the multi-stage power conversion circuit is the first direction, the power conversion circuit farthest from the battery is set to start voltage stabilization first, and then starting with the energy storage device, the voltage stabilization of each power conversion circuit is started in sequence;

If the current flow direction of the multi-stage power conversion circuit is the second direction, the power conversion circuit farthest from the battery is set to start voltage regulation first, and then the voltage regulation of each power conversion circuit is started in sequence starting with the power conversion circuit farthest from the battery;

The current flowing in the first direction means that the current flows from the energy storage device to the external power supply, and the current flowing in the second direction means that the current flows from the external power supply to the energy storage device.

In a possible implementation, determining the voltage stabilization point of each level of the power conversion circuit according to the current flow direction of the multi-level power conversion circuit includes:

If the current flow direction of the multi-stage power conversion circuit is the first direction, the voltage stabilization point of the primary power conversion circuit is set to its output voltage, and the voltage stabilization points of the other power conversion circuits are set to their input voltages;

If the current flow direction of the multi-stage power conversion circuit is the second direction, the voltage stabilization point of each stage of the power conversion circuit is set to be its output voltage;

Among them, the current flow direction of the first direction refers to the current flowing from the energy storage device to the external power supply, and the current flow direction of the second direction refers to the current flowing from the external power supply to the energy storage device; the primary power conversion circuit is the first-stage power conversion circuit starting from the energy storage device, and the other power conversion circuits of each stage are other power conversion circuits except the primary power conversion circuit.

In another aspect of the present invention, a multi-stage power conversion circuit voltage stabilization device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the multi-stage power conversion circuit voltage stabilization method described above when executing the computer program.

On the other hand, the present invention also provides a power conversion system, comprising: the multi-stage power conversion circuit used above and the multi-stage power conversion circuit voltage stabilizing device described above, wherein the multi-stage power conversion circuit is connected to the multi-stage power conversion circuit voltage stabilizing device.

The beneficial effects of the multi-stage power conversion circuit voltage stabilization method and device, and the power conversion system provided by the present invention are:

Different from the prior art, the present invention provides a voltage stabilization scheme for multi-stage power conversion circuits applicable to wide voltage range scenarios, specifically, the order of starting voltage stabilization of power conversion circuits at each stage and the voltage stabilization points of power conversion circuits at each stage are determined according to the current flow direction in the multi-stage power conversion circuit, the voltage reference value corresponding to each voltage stabilization point is determined according to the required voltage and the current flow direction in the multi-stage power conversion circuit, and finally the voltage stabilization is performed based on the voltage reference value corresponding to each voltage stabilization point and the current flow direction in the multi-stage power conversion circuit. The present invention takes into account the differences in the required voltages of different energy storage devices and the voltage stabilization reference values of power conversion circuits at each stage under different battery charge and discharge states, and can adaptively adjust the voltage stabilization parameters according to the required voltage and the battery charge and discharge state, thereby achieving effective voltage stabilization of multi-stage power conversion circuits under a wide voltage range.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic flow chart of a voltage stabilization method for a multi-stage power conversion circuit provided by an embodiment of the present invention;

FIG2 is a schematic diagram of the structure of a multi-stage power conversion circuit provided by an embodiment of the present invention;

3 is a schematic diagram of the structure of a multi-stage power conversion circuit voltage stabilization device provided by an embodiment of the present invention;

FIG4 is a schematic diagram of the structure of a power conversion system provided by an embodiment of the present invention;

FIG5 is a schematic diagram of the structure of a multi-stage power conversion circuit provided by another embodiment of the present invention.

DETAILED DESCRIPTION

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Please refer to FIG1 , which is a flow chart of a multi-stage power conversion circuit voltage stabilization method provided by an embodiment of the present invention. The method is applied to a multi-stage power conversion circuit 200 as shown in FIG2 , wherein the multi-stage power conversion circuit 200 includes at least two stages of power conversion circuits connected in series, one side of the at least two stages of power conversion circuits connected in series is used to connect to an energy storage device, and the other side is used to connect to an external power source, and the external power source can be a DC source or an AC source. The power conversion circuit can be a DC/DC circuit or a DC/AC circuit.

The multi-stage power conversion circuit voltage stabilization method comprises:

S101: Obtaining the required voltage of the energy storage device and the current flow direction of the multi-stage power conversion circuit.

In this embodiment, the current flow direction of the multi-stage power conversion circuit is the second direction or the first direction, wherein the current flow direction in the first direction means that the current flows from the energy storage device to the external power supply, and the current flow direction in the second direction means that the current flows from the external power supply to the energy storage device.

In this embodiment, the required voltage of the energy storage device can be determined according to the rated capacity of the energy storage device. When the required voltage is variable, it can also be determined according to the number of minimum energy storage units (for example, it can be determined according to the number of batteries).

S102: Determine the voltage stabilization point of each level of the power conversion circuit and the voltage stabilization sequence of each level of the power conversion circuit according to the current flow direction of the multi-level power conversion circuit.

In this embodiment, the voltage stabilization sequence of each stage of the power conversion circuit refers to the order in which the power conversion circuits of each stage start voltage stabilization, and the voltage stabilization point of each stage of the power conversion circuit refers to the specific voltage stabilization position of each stage of the power conversion circuit (for example, the output voltage of each stage of the power conversion circuit can be stabilized, and it can also be stabilized according to the input voltage of each stage of the conversion circuit).

S103: Determine the voltage reference value corresponding to each voltage stabilization point according to the required voltage and the current flow direction of the multi-stage power conversion circuit.

In this embodiment, the voltage reference values corresponding to the various voltage stabilization points may be input voltage reference values corresponding to various levels of power conversion circuits, or may be output voltage reference values corresponding to various levels of power conversion circuits.

S104: performing voltage stabilization control on each level of the power conversion circuit based on the voltage reference value corresponding to each voltage stabilization point and the voltage stabilization sequence of each level of the power conversion circuit.

In this embodiment, the voltage stabilization of each level of the power conversion circuit can be started in sequence according to the voltage stabilization order of each level of the power conversion circuit. After starting the voltage stabilization, the power conversion circuits of each level perform voltage stabilization control based on the voltage reference value corresponding to their voltage stabilization points. The specific voltage stabilization control scheme is the existing technology and will not be repeated here.

From the above description, it can be seen that, different from the prior art, the embodiment of the present invention provides a voltage stabilization scheme for multi-stage power conversion circuits applicable to wide voltage range scenarios, specifically, the order of starting voltage stabilization of power conversion circuits at each stage and the voltage stabilization points of power conversion circuits at each stage are determined according to the current flow direction in the multi-stage power conversion circuit, the voltage reference value corresponding to each voltage stabilization point is determined according to the required voltage and the current flow direction in the multi-stage power conversion circuit, and finally the voltage stabilization is performed based on the voltage reference value corresponding to each voltage stabilization point and the current flow direction in the multi-stage power conversion circuit. The embodiment of the present invention takes into account the differences in the required voltages of different energy storage devices and the voltage stabilization reference values of power conversion circuits at each stage under different battery charge and discharge states, and can adaptively adjust the voltage stabilization parameters according to the required voltage and the battery charge and discharge state, thereby achieving effective voltage stabilization of multi-stage power conversion circuits under a wide voltage range.

In a possible implementation, determining a voltage reference value corresponding to each voltage stabilization point according to a required voltage and a current flow direction of a multi-stage power conversion circuit includes:

If the current flow direction of the multi-stage power conversion circuit is in the first direction, the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit and the voltage reference value corresponding to the voltage stabilization point of the final power conversion circuit are determined according to the required voltage, and the voltage reference value corresponding to the voltage stabilization point of the intermediate power conversion circuits is determined according to the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit and the preset voltage difference between adjacent power conversion circuits.

Among them, the primary power conversion circuit is the first power conversion circuit starting from the energy storage device, the final power conversion circuit is the last power conversion circuit starting from the energy storage device, and the intermediate power conversion circuits are other power conversion circuits except the primary power conversion circuit and the final power conversion circuit. In other words, the primary power conversion circuit is the closest to the energy storage device, and the final power conversion circuit is the closest to the external power supply. The counting direction is from the energy storage device end to the external power supply end.

In a possible implementation, determining a voltage reference value corresponding to a voltage stabilization point of a primary power conversion circuit and a voltage reference value corresponding to a voltage stabilization point of a final power conversion circuit according to a required voltage includes:

Determine the range into which the required voltage falls.

The voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit and the voltage reference value corresponding to the voltage stabilization point of the final power conversion circuit are determined according to the range to which the required voltage belongs and various preset reference values corresponding to the range.

In this embodiment, the correspondence between the above-mentioned range and the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit and the voltage reference value corresponding to the voltage stabilization point of the final power conversion circuit can be pre-set. After determining the range to which the required voltage belongs, the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit and the voltage reference value corresponding to the voltage stabilization point of the final power conversion circuit are determined according to the required voltage and the correspondence.

In this embodiment, after determining the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit, the reference value corresponding to the voltage stabilization point of the next power conversion circuit can be determined according to the preset voltage difference between the primary power conversion circuit and the next power conversion circuit (the next power conversion circuit is recorded as the second power conversion circuit). After determining the voltage reference value corresponding to the voltage stabilization point of the second power conversion circuit, the voltage reference value corresponding to the voltage stabilization point of the next power conversion circuit can be determined according to the preset voltage difference between the second power conversion circuit and the next power conversion circuit, and so on, until the voltage reference values corresponding to the voltage stabilization points of all power conversion circuits are obtained. Among them, the preset voltage difference between each two adjacent power conversion circuits can be the same or different, which is not limited here.

In a possible implementation, a method for determining a preset voltage difference between adjacent power conversion circuits of each level is as follows:

Get the boost ratio of a multi-stage power conversion circuit.

The preset voltage difference between adjacent power conversion circuits of each level is determined according to the voltage boost ratio.

In this embodiment, in order to ensure that energy flows from the battery side to the external circuit side, it is necessary to set a certain difference between the voltage reference values corresponding to each stage of the power conversion circuit. On this basis, in order to ensure the boost ratio of the multi-stage power conversion circuit, it is necessary to impose certain limitations on this voltage difference. Therefore, this embodiment may consider determining the preset voltage difference between adjacent power conversion circuits at each stage according to the boost ratio of the multi-stage power conversion circuit.

In a possible implementation, determining a voltage reference value corresponding to each voltage stabilization point according to a required voltage and a current flow direction of a multi-stage power conversion circuit includes:

If the current flow direction of the multi-stage power conversion circuit is the second direction, the preset charging voltage of the energy storage device is obtained, and the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit is determined according to the preset charging voltage, and the voltage reference value corresponding to the voltage stabilization point of the final power conversion circuit and the intermediate power conversion circuits is determined according to the required voltage.

Among them, the primary power conversion circuit is the first power conversion circuit starting from the energy storage device, the final power conversion circuit is the last power conversion circuit starting from the energy storage device, and the intermediate power conversion circuits are other power conversion circuits except the primary power conversion circuit and the final power conversion circuit. In other words, the primary power conversion circuit is the closest to the energy storage device, and the final power conversion circuit is the closest to the external power supply. The counting direction is from the energy storage device end to the external power supply end.

In this embodiment, when charging the energy storage device, the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit can be directly set according to the preset charging voltage. If the energy storage device is a battery, the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit can be set according to the battery's average floating charge voltage, wherein the battery's average floating charge voltage can be calculated by multiplying the average floating charge voltage of a single battery by the number of battery cells.

In a possible implementation, determining voltage reference values corresponding to voltage stabilization points of the final power conversion circuit and intermediate power conversion circuits according to the required voltage includes:

Determine the range into which the required voltage falls.

The voltage reference values corresponding to the voltage stabilization points of the final power conversion circuit and the intermediate power conversion circuits are determined according to the range to which the required voltage belongs and various preset reference values corresponding to the range.

In this embodiment, the correspondence between the above-mentioned range and the voltage reference value corresponding to the voltage stabilization point of the final power conversion circuit and the voltage reference value corresponding to the voltage stabilization points of the intermediate power conversion circuits can be pre-set. After determining the range to which the required voltage belongs, the voltage reference value corresponding to the voltage stabilization point of the final power conversion circuit and the voltage reference value corresponding to the voltage stabilization points of the intermediate power conversion circuits can be determined based on the required voltage and the correspondence.

In a possible implementation, determining a voltage stabilization sequence of each level of the power conversion circuit according to the current flow direction of the multi-level power conversion circuit includes:

If the current flow direction of the multi-stage power conversion circuit is the first direction, the power conversion circuit farthest from the battery is set to start voltage regulation first, and then starting with the energy storage device, the voltage regulation of each power conversion circuit is started in sequence.

If the current flow direction of the multi-stage power conversion circuit is the second direction, the power conversion circuit farthest from the battery is set to start voltage regulation first, and then the voltage regulation of each power conversion circuit is started in sequence starting with the power conversion circuit farthest from the battery.

In a possible implementation, determining the voltage stabilization point of each level of the power conversion circuit according to the current flow direction of the multi-level power conversion circuit includes:

If the current flow direction of the multi-stage power conversion circuit is the first direction, the voltage stabilization point of the primary power conversion circuit is set to its output voltage, and the voltage stabilization points of the other power conversion circuits are set to their input voltages.

If the current flow direction of the multi-stage power conversion circuit is the second direction, the voltage stabilization points of each stage of the power conversion circuit are set to their output voltages. In a possible implementation, the present invention takes the multi-stage power conversion circuit including three-stage power conversion circuits connected in series, the energy storage device is a battery, and the external power supply is a power grid as an example to explain the above scheme in detail. As shown in Figure 5, the three-stage power conversion circuit includes a first-stage DC/DC circuit (starting from the battery end), a second-stage DC/DC circuit, and a DC/AC circuit connected in series in sequence, wherein the first-stage DC/DC circuit is also connected to the battery, and the DC/AC circuit is also connected to the power grid, and the input voltage reference value of each stage of the power conversion circuit is used as the voltage reference value corresponding to each voltage stabilization point. The input voltage reference value corresponding to the first-stage DC/DC circuit is recorded as Uref1, the input voltage reference value corresponding to the second-stage DC/DC circuit is recorded as Uref2, and the input voltage reference value corresponding to the DC/AC circuit is recorded as Uref3. The number of battery cells is set to 6 to 75, and the required voltage range of the corresponding battery is 9 to 180V, wherein the preset voltage difference between the first-stage DC/DC circuit and the second-stage DC/DC circuit is 20V. According to the above scheme:

If the current flow direction of the multi-stage power conversion circuit is the battery discharge direction (that is, the first direction), the voltage stabilization points for starting the voltage stabilization of the multi-stage power conversion circuit are: the output voltage of the first-stage DC/DC circuit (denoted as Uref1), the input voltage of the second-stage DC/DC circuit (denoted as Uref2), and the input voltage of the DC/AC circuit (denoted as Uref3). The order for starting the voltage stabilization of the multi-stage power conversion circuit is: the DC/AC circuit is first stabilized to Uref3, then the first-stage DC/DC circuit is stabilized to Uref1, and finally the second-stage DC/DC circuit is stabilized to Uref2.

If the current flow direction of the multi-stage power conversion circuit is the battery charging direction (that is, the second direction), the voltage stabilization points for starting the voltage stabilization of the multi-stage power conversion circuit are: the output voltage of the first-stage DC/DC circuit (denoted as Uref4), the output voltage of the second-stage DC/DC circuit (denoted as Uref5), and the output voltage of the DC/AC circuit (denoted as Uref6). The order for starting the voltage stabilization of the multi-stage power conversion circuit is: the DC/AC circuit is first stabilized to Uref6, then the second-stage DC/DC circuit is stabilized to Uref5, and finally the first-stage DC/DC circuit is stabilized to Uref4.

When the current flow direction of the multi-stage power conversion circuit is the battery discharge direction:

If the number of battery cells is not greater than 15, set Uref1=70V, Uref3=180V, where Uref2=Uref1-20V=50V.

If the number of battery cells is greater than 15 and less than 35, set Uref1=120V, Uref3=200V, wherein Uref2=Uref1-20V=100V.

If the number of battery cells is greater than 36 and less than 55, set Uref1=180V, Uref3=220V, where Uref2=Uref1-20V=160V.

If the number of battery cells is greater than 55 and less than 75, set Uref1=240V, Uref3=260V, where Uref2=Uref1-20V=220V.

In this embodiment, the main voltage stabilization object is Uref3. At this time, the boost ratio is controlled within 5 times (the lower the boost ratio, the higher the circuit efficiency), and the efficiency of the overall circuit will be relatively high. During discharge, it is necessary to ensure that Uref2<Uref1 to ensure that energy moves to the grid side. Taking into account the sampling error, it is necessary to ensure that the difference between Uref2 and Uref1 is greater than a certain value. However, if the low voltage is too low, it may be impossible to ensure a 5-fold voltage ratio. Therefore, this embodiment sets a preset difference. The preset voltage difference between the first-stage DC/DC circuit and the second-stage DC/DC circuit is 10~20V (the preset voltage difference used in this embodiment is 20V).

When the current of the multi-stage power conversion circuit flows in the direction of battery charging:

Uref4 is determined according to the average floating charge voltage of the battery.

If the number of battery cells is not greater than 15, set Uref5=50V and Uref6=180V.

If the number of battery cells is greater than 15 and less than 35, set Uref5=100V and Uref6=200V.

If the number of battery cells is greater than 36 and less than 55, set Uref5=160V and Uref6=220V.

If the number of battery cells is greater than 55 and less than 75, set Uref5=220V and Uref6=260V.

In this embodiment, the main voltage stabilization object is Uref4, which can be directly determined according to the battery's average float charge voltage (which can be obtained by multiplying the average float charge voltage of a single battery by the required voltage), and then Uref5 and Uref6 are determined according to the number of battery cells.

In the above-mentioned embodiments, the number of stages of the adopted power conversion circuit can be determined according to the required voltage.

In each of the above embodiments, each power conversion circuit may also be a DC/DC circuit, which can be set according to actual needs.

In another aspect of the present invention, a multi-stage power conversion circuit voltage stabilizing device 300 is provided, comprising: one or more processors 301, one or more input devices 302, one or more output devices 303 and one or more memories 304. The processor 301, input device 302, output device 303 and memory 304 communicate with each other through a communication bus 305. The memory 304 is used to store computer programs, and the computer program includes program instructions. The processor 301 is used to execute the program instructions stored in the memory 304. Among them, the processor 301 is configured to call the program instructions to execute the steps of the above-mentioned method embodiments. It should be understood that in the embodiment of the present invention, the processor 301 can be a central processing unit (CPU). The processor can also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general processor may be a microprocessor or the processor may be any conventional processor, etc. The input device 302 may include a touch panel, a fingerprint sensor (for collecting the user's fingerprint information and the direction information of the fingerprint), a microphone, etc., and the output device 303 may include a display (LCD, etc.), a speaker, etc. The memory 304 may include a read-only memory and a random access memory, and provide instructions and data to the processor 301. A part of the memory 304 may also include a non-volatile random access memory. For example, the memory 304 may also store information about the device type. In a specific implementation, the processor 301, the input device 302, and the output device 303 described in the embodiment of the present invention may execute the implementation described in the first embodiment and the second embodiment of the multi-stage power conversion circuit voltage stabilization method provided in the embodiment of the present invention.

Please refer to Figure 4. On the other hand, the present invention also provides a power conversion system 40, including: the multi-stage power conversion circuit 200 used above and the multi-stage power conversion circuit voltage stabilizing device 300 described above, and the multi-stage power conversion circuit 200 is connected to the multi-stage power conversion circuit voltage stabilizing device 300.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims (9)

1. A voltage stabilization method for a multi-stage power conversion circuit, characterized in that the method is applied to a multi-stage power conversion circuit; the multi-stage power conversion circuit comprises at least two stages of power conversion circuits connected in series, one side of the at least two stages of power conversion circuits connected in series is used to connect to an energy storage device, and the other side is used to connect to an external power source, wherein the external power source is a DC source or an AC source; the method comprises: Obtaining the required voltage of the energy storage device and the current flow direction of the multi-stage power conversion circuit; Determining the voltage stabilization points of each level of the power conversion circuit and the voltage stabilization sequence of each level of the power conversion circuit according to the current flow direction of the multi-level power conversion circuit; Determining a voltage reference value corresponding to each voltage stabilization point according to the required voltage and the current flow direction of the multi-stage power conversion circuit; Based on the voltage reference values corresponding to the various voltage stabilization points and the voltage stabilization sequence of the various power conversion circuits, voltage stabilization control is performed on the various power conversion circuits; Determining the voltage stabilization sequence of each level of the power conversion circuit according to the current flow direction of the multi-level power conversion circuit includes: If the current flow direction of the multi-stage power conversion circuit is the first direction, the power conversion circuit farthest from the energy storage device is set to start voltage stabilization first, and then starting with the energy storage device, the voltage stabilization of each power conversion circuit is started in sequence; If the current flow direction of the multi-stage power conversion circuit is the second direction, the power conversion circuit farthest from the energy storage device is set to start voltage stabilization first, and then the power conversion circuit farthest from the energy storage device is used as the starting point to start voltage stabilization of each power conversion circuit in sequence; The current flowing in the first direction means that the current flows from the energy storage device to the external power supply, and the current flowing in the second direction means that the current flows from the external power supply to the energy storage device. 2. The voltage stabilization method of a multi-stage power conversion circuit according to claim 1, characterized in that the voltage reference value corresponding to each voltage stabilization point is determined according to the required voltage and the current flow direction of the multi-stage power conversion circuit, comprising: If the current flow direction of the multi-stage power conversion circuit is the first direction, the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit and the voltage reference value corresponding to the voltage stabilization point of the final power conversion circuit are determined according to the required voltage, and the voltage reference value corresponding to the voltage stabilization point of each intermediate power conversion circuit is determined according to the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit and the preset voltage difference between adjacent power conversion circuits at each stage; Among them, the current flow direction is the first direction, which means that the current flows from the energy storage device to the external power supply, the primary power conversion circuit is the first-stage power conversion circuit starting from the energy storage device, the final-stage power conversion circuit is the last-stage power conversion circuit starting from the energy storage device, and the intermediate power conversion circuits are other power conversion circuits except the primary power conversion circuit and the final-stage power conversion circuit. 3. The voltage stabilization method for a multi-stage power conversion circuit according to claim 2, characterized in that the step of determining the voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit and the voltage reference value corresponding to the voltage stabilization point of the final power conversion circuit according to the required voltage comprises: Determine the range to which the required voltage belongs; The voltage reference value corresponding to the voltage stabilization point of the primary power conversion circuit and the voltage reference value corresponding to the voltage stabilization point of the final power conversion circuit are determined according to the range to which the required voltage belongs and various preset reference values corresponding to the range. 4. The voltage stabilization method for a multi-stage power conversion circuit according to claim 2, wherein the method for determining the preset voltage difference between adjacent power conversion circuits at each stage is: Obtaining a voltage boost ratio of the multi-stage power conversion circuit; The preset voltage difference between adjacent power conversion circuits of each level is determined according to the boost ratio. 5. The voltage stabilization method of a multi-stage power conversion circuit according to claim 1, wherein the voltage reference value corresponding to each voltage stabilization point is determined according to the required voltage and the current flow direction of the multi-stage power conversion circuit, comprising: If the current flow direction of the multi-stage power conversion circuit is the second direction, a preset charging voltage of the energy storage device is obtained, a voltage reference value corresponding to a voltage stabilization point of the primary power conversion circuit is determined according to the preset charging voltage, and voltage reference values corresponding to voltage stabilization points of the final power conversion circuit and intermediate power conversion circuits are determined according to the required voltage; Among them, the current flowing in the second direction means that the current flows from the external power supply to the energy storage device, the primary power conversion circuit is the first-stage power conversion circuit starting from the energy storage device, the final-stage power conversion circuit is the last-stage power conversion circuit starting from the energy storage device, and the intermediate power conversion circuits are other power conversion circuits except the primary power conversion circuit and the final-stage power conversion circuit. 6. The voltage stabilization method for a multi-stage power conversion circuit according to claim 5, characterized in that the step of determining the voltage reference values corresponding to the voltage stabilization points of the final-stage power conversion circuit and the intermediate-stage power conversion circuits according to the required voltage comprises: Determine the range to which the required voltage belongs; The voltage reference values corresponding to the voltage stabilization points of the final power conversion circuit and the intermediate power conversion circuits are determined according to the range to which the required voltage belongs and various preset reference values corresponding to the range. 7. The voltage stabilization method for a multi-stage power conversion circuit according to any one of claims 1 to 6, characterized in that the voltage stabilization point of each stage of the power conversion circuit is determined according to the current flow direction of the multi-stage power conversion circuit, comprising: If the current flow direction of the multi-stage power conversion circuit is the first direction, the voltage stabilization point of the primary power conversion circuit is set to its output voltage, and the voltage stabilization points of the other power conversion circuits are set to their input voltages; If the current flow direction of the multi-stage power conversion circuit is the second direction, the voltage stabilization point of each stage of the power conversion circuit is set to be its output voltage; Among them, the current flow direction of the first direction refers to the current flowing from the energy storage device to the external power supply, and the current flow direction of the second direction refers to the current flowing from the external power supply to the energy storage device; the primary power conversion circuit is the first-stage power conversion circuit starting from the energy storage device, and the other power conversion circuits of each stage are other power conversion circuits except the primary power conversion circuit. 8. A multi-stage power conversion circuit voltage stabilization device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method as claimed in any one of claims 1 to 6 when executing the computer program. 9. A power conversion system, characterized in that it comprises: a multi-stage power conversion circuit as applied in claim 1 and a multi-stage power conversion circuit voltage stabilizing device as described in claim 8, wherein the multi-stage power conversion circuit is connected to the multi-stage power conversion circuit voltage stabilizing device.