CN116961454A - Bus midpoint balance circuit, inverter and energy storage system - Google Patents

Abstract

The application discloses a bus midpoint balance circuit, an inverter and an energy storage system. The bus midpoint balancing circuit comprises a positive bus capacitor, a negative bus capacitor and a voltage balancing module. The positive bus capacitor and the negative bus capacitor are connected in series, and two ends of a circuit formed by connecting the positive bus capacitor and the negative bus capacitor in series are connected with an input power supply. The voltage balancing module is respectively connected with the positive bus capacitor and the negative bus capacitor, and is used for controlling the positive bus capacitor to discharge or the negative bus capacitor to charge so as to reduce a first difference value between the voltage of the positive bus capacitor and the voltage of the negative bus capacitor, or is used for controlling the negative bus capacitor to discharge or the positive bus capacitor to charge so as to increase the first difference value. By the mode, the voltage balance of the positive direct current bus capacitor and the negative direct current bus capacitor can be adjusted by controlling the charge and discharge of the positive bus capacitor or the negative bus capacitor.

Description

Bus midpoint balancing circuit, inverter and energy storage system

Technical field

This application relates to the field of inverter technology, and in particular to a bus midpoint balancing circuit, inverter and energy storage system.

Background technique

In current three-phase household energy storage systems, inverters commonly use three-level topology. Therefore, there are positive bus capacitance and negative bus capacitance in bus capacitance.

For three-level inverters, when the positive DC bus capacitance is inconsistent with the negative DC bus capacitance, the on-time and off-time of the switching device are inconsistent, etc., it may cause the positive DC bus capacitance to be inconsistent with the negative DC bus capacitance. The voltage across the capacitor is unbalanced. This can worsen power quality and even damage components in the inverter. Therefore, it is particularly important to keep the voltages of the positive DC bus capacitor and the negative DC bus capacitor balanced.

Contents of the invention

This application aims to provide a bus midpoint balancing circuit, inverter and energy storage system that can adjust the voltage balance of the positive bus capacitance and the negative bus capacitance by controlling the charge and discharge of the positive bus capacitance or the negative bus capacitance.

In order to achieve the above purpose, in the first aspect, this application provides a bus midpoint balancing circuit, including:

Positive bus capacitor and negative bus capacitor, the positive bus capacitor and the negative bus capacitor are connected in series, and both ends of the circuit composed of the positive bus capacitor and the negative bus capacitor in series are connected to the input power supply;

A voltage balance module, the voltage balance module is connected to the positive bus capacitor and the negative bus capacitor respectively, and the voltage balance module is used to control the discharge of the positive bus capacitor or the charging of the negative bus capacitor to reduce the The first difference between the voltage of the positive bus capacitor and the voltage of the negative bus capacitor, or the voltage balance module is used to control the discharge of the negative bus capacitor or the charging of the positive bus capacitor to increase the Describe the first difference.

In an optional manner, the voltage balancing module includes a controller, a switch branch and an impedance branch;

The controller is connected to the positive bus capacitor and the negative bus capacitor respectively. The controller is used to obtain the first voltage of the positive bus capacitor and the second voltage of the negative bus capacitor, and calculate the voltage based on the first voltage of the positive bus capacitor. A voltage and the second voltage output a first control signal or a second control signal;

The switch branch is connected to the controller, the impedance branch, the positive bus capacitor and the negative bus capacitor respectively, and the switch branch is used to be in a first state in response to the first control signal. a conductive state such that the positive bus capacitance is discharged through the impedance branch and the negative bus capacitance is charged through the impedance branch, or the switching branch is configured to operate in response to the second control signal In the second conductive state, the negative bus capacitance is discharged through the impedance branch and the positive bus capacitance is charged through the impedance branch.

In an optional manner, the switch branch includes a first switch and a second switch;

The first switch is connected to the second switch, the positive bus capacitor and the impedance branch respectively, and the second switch is connected to the negative bus capacitor and the impedance branch respectively;

When the first switch is turned on in response to the first control signal and the second switch is turned off, the switch branch is in a first conductive state;

When the second switch is turned on in response to the second control signal and the first switch is turned off, the switch branch is in a second conductive state.

In an optional manner, the control end of the first switch and the control end of the second switch are both connected to the controller, and the first end of the first switch is connected to the positive bus capacitor. The first end is connected, the second end of the first switch is connected to the first end of the second switch and the first end of the impedance branch, and the second end of the impedance branch is respectively connected to the The second end of the positive bus capacitor is connected to the first end of the negative bus capacitor, and the second end of the second switch is connected to the second end of the negative bus capacitor.

In an optional manner, the impedance branch includes a first inductor;

The first end of the first inductor is connected to the switch branch, and the second end of the first inductor is connected to the positive bus capacitor and the negative bus capacitor respectively.

In an optional manner, the impedance branch includes a first resistor;

The first end of the first resistor is connected to the switch branch, and the second end of the first resistor is connected to the positive bus capacitor and the negative bus capacitor respectively.

In a second aspect, this application provides an inverter, including an inverter module and a bus midpoint balancing circuit as described above;

The inverter module is connected to the positive bus capacitor, the negative bus capacitor and the load respectively. The inverter module is used to convert the voltage between the positive bus capacitor and the negative bus capacitor into a first AC voltage, and power the load based on the first AC voltage.

In an optional manner, the input power supply of the inverter includes photovoltaic components, and the inverter further includes a maximum power point tracking module;

The maximum power point tracking module is respectively connected to the photovoltaic module, the positive bus capacitor and the negative bus capacitor. The maximum power point tracking module is used to maintain the maximum power output of the photovoltaic module to the positive bus capacitor. and the negative bus capacitance.

In an optional manner, the input power supply of the inverter includes a battery, and the inverter further includes a DC-DC converter module;

The DC-DC converter module is connected to the battery, the positive bus capacitor and the negative bus capacitor respectively. The DC-DC converter module is used to convert the voltage output by the battery into a first DC voltage, and Input to the positive bus capacitance and the negative bus capacitance.

In a third aspect, this application provides an energy storage system, including an input power supply, a load, and an inverter as described above.

In an optional manner, the input power source includes photovoltaic components and/or batteries;

The load includes electrical equipment and/or a power grid.

The beneficial effects of this application are: the bus midpoint balancing circuit provided by this application includes a positive bus capacitor, a negative bus capacitor and a voltage balance module. Wherein, the positive bus capacitor and the negative bus capacitor are connected in series, and both ends of the circuit composed of the positive bus capacitor and the negative bus capacitor in series are connected to the input power supply. The voltage balance module is connected to the positive bus capacitor and the negative bus capacitor respectively. The voltage balance module is used to control the discharge of the positive bus capacitor or the charging of the negative bus capacitor to reduce the first difference between the voltage of the positive bus capacitor and the voltage of the negative bus capacitor. value, or the voltage balancing module is used to control the discharge of the negative bus capacitance or the charging of the positive bus capacitance to increase the first difference value. Through the above method, when the absolute value of the first difference between the voltage of the positive bus capacitor and the voltage of the negative bus capacitor is too large, the charging and discharging of the positive bus capacitor or the negative bus capacitor can be controlled to adjust the relationship between the positive bus capacitance and the negative bus capacitor. Voltage balancing of bus capacitors.

Description of the drawings

One or more embodiments are exemplified by the pictures in the corresponding drawings. These illustrative illustrations do not constitute limitations to the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings are not intended to be limited to scale.

Figure 1 is a schematic structural diagram of a bus midpoint balancing circuit provided in Embodiment 1 of the present application;

Figure 2 is a schematic structural diagram of a bus midpoint balancing circuit provided in Embodiment 2 of the present application;

Figure 3 is a schematic structural diagram of a bus midpoint balancing circuit provided in Embodiment 3 of the present application;

Figure 4 is a schematic structural diagram of a bus midpoint balancing circuit provided in Embodiment 4 of the present application;

Figure 5 is a schematic structural diagram of a bus midpoint balancing circuit provided in Embodiment 5 of the present application;

Figure 6 is a schematic structural diagram of an inverter provided in Embodiment 1 of the present application;

Figure 7 is a schematic circuit structure diagram of the inverter module provided in Embodiment 1 of the present application;

Figure 8 is a schematic structural diagram of an inverter provided in Embodiment 2 of the present application;

Figure 9 is a schematic circuit structure diagram of the maximum power point tracking module provided in Embodiment 1 of the present application;

Figure 10 is a schematic structural diagram of an inverter provided in Embodiment 3 of the present application;

Figure 11 is a schematic circuit structure diagram of the DC-DC converter module provided in Embodiment 1 of the present application;

Figure 12 is a schematic structural diagram of an inverter provided in Embodiment 4 of the present application.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments These are part of the embodiments of this application, but not all of them. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

Please refer to FIG. 1 , which is a schematic structural diagram of a bus midpoint balancing circuit provided by an embodiment of the present application. As shown in FIG. 1 , the bus midpoint balancing circuit 100 includes a positive bus capacitor C1 , a negative bus capacitor C2 and a voltage balancing module 10 .

The positive bus capacitor C1 and the negative bus capacitor C2 are connected in series, and both ends of the circuit composed of the positive bus capacitor C1 and the negative bus capacitor C2 are connected in series to the input power supply 200 . Specifically, the first terminal of the positive bus capacitor C1 is connected to the first terminal of the input power supply 200 , the second terminal of the positive bus capacitor C1 is connected to the first terminal of the negative bus capacitor C2 , and the second terminal of the negative bus capacitor C2 is connected to the input power supply 200 . The second terminal of power supply 200 is connected.

The voltage balancing module 10 is connected to the positive bus capacitor C1 and the negative bus capacitor C2 respectively. Specifically, the first end of the voltage balancing module 10 is connected to the first end of the positive bus capacitor C1, and the second end of the voltage balancing module 10 is connected to the second end of the negative bus capacitor C2.

In this embodiment, the voltage balancing module 10 is used to control the discharge of the positive bus capacitor C1 or the charging of the negative bus capacitor C2 to reduce the first difference between the voltage of the positive bus capacitor C1 and the voltage of the negative bus capacitor C2, or , the voltage balance module 10 is used to control the discharge of the negative bus capacitor C2 or the charging of the positive bus capacitor C1 to increase the first difference. In practical applications, when the absolute value of the first difference between the voltage of the positive bus capacitor C1 and the voltage of the negative bus capacitor C2 is too large (for example, the first difference is a positive value and the first difference is greater than the first predetermined value). When a difference is set; for another example, when the first difference is a negative value and the first difference is less than the second preset difference, where the first preset difference＞0＞the second preset difference), by controlling By charging and discharging the positive bus capacitor C1 or the negative bus capacitor C2, the voltage balance between the positive bus capacitor C1 and the negative bus capacitor C2 can be adjusted.

In one embodiment, as shown in FIG. 2 , the voltage balancing module 10 includes a controller 11 , a switch branch 12 and an impedance branch 13 .

Among them, the controller 11 is connected to the positive bus capacitor C1 and the negative bus capacitor C2 respectively. The switch branch 12 is connected to the controller 11, the impedance branch 13, the positive bus capacitor C1 and the negative bus capacitor C2 respectively. Specifically, the first end of the switch branch 12 is connected to the controller 11, the second end of the switch branch 12 is connected to the first end of the impedance branch 13, and the second end of the impedance branch 13 is respectively connected to the positive bus capacitor C1. The second end of the switch branch 12 is connected to the first end of the negative bus capacitor C2, the third end of the switch branch 12 is connected to the first end of the positive bus capacitor C1, and the fourth end of the switch branch 12 is connected to the second end of the negative bus capacitor C2. end connection.

In some embodiments, the controller 11 may be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a microcontroller, an ARM (Acorn RISC Machine), or other Programmed logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of these components. Furthermore, the controller 11 may also be any conventional processor, controller, microcontroller or state machine. The controller 11 may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in combination with a DSP, and/or any other such configuration.

In this embodiment, the controller 11 is used to obtain the first voltage of the positive bus capacitor C1 and the second voltage of the negative bus capacitor C2, and output a first control signal or a second control signal based on the first voltage and the second voltage. The switching branch 12 is configured to be in a first conductive state in response to the first control signal, so that the positive bus capacitance C1 is discharged through the impedance branch 13 and the negative bus capacitance C2 is charged through the impedance branch 13, or the switching branch 12 For being in the second conductive state in response to the second control signal, so that the negative bus capacitance C2 is discharged through the impedance branch 13 and the positive bus capacitance C1 is charged through the impedance branch 13 .

In one embodiment, as shown in FIG. 3 , the switch branch 12 includes a first switch K1 and a second switch K2.

Among them, the first switch K1 is connected to the second switch K2, the positive bus capacitor C1 and the impedance branch 13 respectively, and the second switch K2 is connected to the negative bus capacitor C2 and the impedance branch 13 respectively.

Specifically, the control end of the first switch K1 and the control end of the second switch K2 are both connected to the controller 11, the first end of the first switch K1 is connected to the first end of the positive bus capacitor C1, and the third end of the first switch K1 The two ends are connected to the first end of the second switch K2 and the first end of the impedance branch 13 respectively. The second end of the second switch K2 is connected to the second end of the second capacitor C2. The second end of the impedance branch 13 They are respectively connected to the second terminal of the positive bus capacitor C1 and the first terminal of the negative bus capacitor C2.

In this embodiment, when the first switch K1 is turned on in response to the first control signal and the second switch K2 is turned off, the switch branch 12 is in the first conductive state. When the second switch K2 is turned on in response to the second control signal and the first switch K1 is turned off, the switch branch 12 is in the second conductive state.

In one embodiment, the impedance branch 13 includes a first inductor L1.

The first end of the first inductor L1 is connected to the switch branch 12 , and the second end of the first inductor L1 is connected to the positive bus capacitor C1 and the negative bus capacitor C2 respectively. Specifically, the first end of the first inductor L1 is connected to the second end of the first switch K1 and the first end of the second switch K2 respectively, and the second end of the first inductor L1 is connected to the positive bus capacitor C1 and the negative bus capacitor respectively. C2 connection.

In the embodiment shown in Figure 3, when the first switch K1 is closed and the second switch K2 is turned off, the positive bus capacitor C1, the first switch K1 and the first inductor L1 form a loop, and the positive bus capacitor C1 passes through the first Inductor L1 discharges. At the same time, the negative bus capacitor C2 is charged through the first inductor L1. Then, the voltage on the positive bus capacitor C1 decreases, and the first difference between the voltage of the positive bus capacitor C1 and the voltage of the negative bus capacitor C2 decreases.

When the first switch K1 is turned off and the second switch K2 is turned on, the negative bus capacitor C2, the second switch K2 and the first inductor L1 form a loop, and the negative bus capacitor C2 is discharged through the first inductor L1. At the same time, the positive bus capacitor C1 is charged through the first inductor L1. Then, the voltage on the negative bus capacitor C2 decreases, and the first difference between the voltage of the positive bus capacitor C1 and the voltage of the negative bus capacitor C2 increases.

Through the above method, when the absolute value of the first difference between the voltage of the positive bus capacitor C1 and the voltage of the negative bus capacitor C2 is too large, the positive bus capacitor C1 or the negative bus capacitor C2 can be controlled to charge and discharge to adjust the positive bus capacitor C1 or the negative bus capacitor C2. The voltage of bus capacitor C1 is balanced with the negative bus capacitor C2.

Among them, the first switch K1 and the second switch K2 can be any controllable switch, such as an insulated gate bipolar transistor (IGBT) device, an integrated gate commutated thyristor (IGCT) device, or a gate turn-off thyristor (GTO). devices, silicon controlled rectifier (SCR) devices, junction field effect transistor (JFET) devices, MOS controlled thyristor (MCT) devices, etc. In addition, the first switch K1 and the second switch K2 shown in FIG. 3 can be implemented as a plurality of switches connected in parallel.

For example, as shown in FIG. 4 , FIG. 4 exemplarily shows that the first switch K1 and the second switch K2 are both IGBT switching tubes.

Wherein, the gates of the first switch K1 and the second switch K2 are both connected to the controller 11, the drain of the first switch K1 is connected to the first end of the first capacitor C1, and the source of the first switch K1 is connected to the second capacitor C1. The drain of the switch K2 is connected to the first end of the first inductor L1, and the source of the second switch K2 is connected to the second end of the second capacitor C2.

In another embodiment, as shown in Figure 5, the impedance branch 13 includes a first resistor R1.

The first end of the first resistor R1 is connected to the switch branch 12 , and the second end of the first resistor R1 is connected to the positive bus capacitor C1 and the negative bus capacitor C2 respectively. Specifically, the first end of the first resistor R1 is connected to the second end of the first switch K1 and the first end of the second switch K2 respectively, and the second end of the first resistor R1 is connected to the positive bus capacitor C1 and the negative bus capacitor respectively. C2 connection.

Specifically, for the specific implementation process of the first resistor R1, reference can be made to the detailed description of the first inductor L1, which will not be described again here. In subsequent embodiments of the present application, the first inductor L1 is used as an example for description.

Of course, in other embodiments, the impedance branch 13 may also include a first resistor R1 and a first inductor L1, which are within the scope of those skilled in the art and will not be described again here.

An embodiment of the present application also provides an inverter. As shown in FIG. 6 , the inverter 1000 includes an inverter module 101 and the bus midpoint balancing circuit 100 in any embodiment of the present application.

Among them, the inverter module 101 is connected to the positive bus capacitor C1, the negative bus capacitor C2 and the load 300 respectively.

Specifically, the inverter module 101 is used to convert the voltage between the positive bus capacitor C1 and the negative bus capacitor C2 into a first AC voltage, and provide power to the load 300 based on the first AC voltage.

Please refer to FIG. 7 , which exemplarily shows a circuit structure of the inverter module 101 .

As shown in Figure 7, the inverter module 101 includes a seventh switching tube Q7, an eighth switching tube Q8, a ninth switching tube Q9, a tenth switching tube Q10, an eleventh switching tube Q11, a twelfth switching tube Q12. The thirteenth switch Q13, the fourteenth switch Q14, the fifteenth switch Q15, the sixteenth switch Q16, the seventeenth switch Q17, the eighteenth switch Q18, the first inverter inductor L11, the second Inverter inductor L12, third inverter inductor L13, first inverter capacitor C11, second inverter capacitor C12 and third capacitor C13.

The connection relationship between various components can be referred to Figure 7 and will not be described again here. In this embodiment, the Pulse Width Modulation (PWM) signal output by the controller 11 is used to control the turn-on and turn-off of each switch tube, thereby realizing the direct current on the positive bus capacitor C1 and the negative bus capacitor C2. The voltage is converted to AC voltage and the load 300 is powered based on the AC voltage. The specific implementation process is well known to those skilled in the art and will not be described again here. The load 300 may be a power grid and/or electrical equipment.

In one embodiment, as shown in FIG. 8 , the input power supply 200 of the inverter 1000 includes a photovoltaic component PV, and the inverter 1000 further includes a maximum power point tracking module 102 .

Among them, the maximum power point tracking module 102 is connected to the photovoltaic module PV, the positive bus capacitor C1 and the negative bus capacitor C2 respectively.

Specifically, the maximum power point tracking module 102 is used to maintain the maximum power output of the photovoltaic module PV to the positive bus capacitance C1 and the negative bus capacitance C2. The maximum power point tracking module 102 optimizes energy output by tracking the maximum power point of the solar panel. This allows the system to operate at maximum efficiency and extract the greatest amount of energy from sunlight. Taking a linear circuit as an example, when the resistance of the load is equal to the internal resistance of the photovoltaic module PV, the photovoltaic module PV has maximum power output.

Photovoltaic module PV is a power generation module composed of multiple solar cells connected in series or parallel. It is mainly used in solar photovoltaic power generation systems. Photovoltaic modules are usually protected by a transparent glass or plastic encapsulation material that converts solar energy into direct current energy that can be used by other electrical equipment or stored in batteries for backup.

Please refer to FIG. 9 , which exemplarily shows a circuit structure of the maximum power point tracking module 102 .

In this embodiment, the maximum power point tracking module 102 includes a first switch Q1, a second switch Q2, a second inductor L2, a first diode D1, a second diode D2, a third capacitor C3, The fourth capacitor C4 and the fifth capacitor C5.

Among them, the first end of the second inductor L2 is connected to the photovoltaic component PV, and the second end of the second inductor L2 is connected to the anode of the second diode and the third end of the first switching tube Q1 respectively. The first switching tube Q1 The first end of the second switch transistor Q2 and the first end of the second switch transistor Q2 are both connected to the controller 11. The second end of the first switch transistor Q1 is respectively connected to the third end of the second switch transistor Q2 and the second end of the third capacitor C3. connection, the second terminal of the second switching tube Q2 is respectively connected to the second terminal of the negative bus capacitor C2 and the second terminal of the fourth capacitor C4, and the cathode of the second diode D2 is respectively connected to the anode of the first diode D1. is connected to the first end of the third capacitor C3, the cathode of the first diode D1 is connected to the first end of the positive bus capacitor C1 and the first end of the fourth capacitor C4 respectively, the fifth capacitor C5 and the fourth capacitor C4 are connected in parallel. connect.

Specifically, when the first switch Q1 is driven to be turned on and the second switch Q2 is turned off, the photovoltaic component PV, the first switch Q1, the third capacitor C3, and the first diode D1 form a loop; when the When the first switching tube Q1 and the second switching tube Q2 are both driven to conduct, the photovoltaic module PV, the first switching tube Q1, and the second switching tube Q2 form a loop; when the second switching tube Q2 is driven to conduct, and the first switch When the tube Q1 is turned off, the photovoltaic module PV, the second inductor L2, the second diode D2, the third capacitor C3 and the second switching tube Q2 form a loop; when the first switching tube Q1 and the second switching tube Q2 are both turned off When , the photovoltaic component PV, the second diode D2, and the first diode D1 form a loop.

Among them, the fourth capacitor C4 and the fifth capacitor C5 are both used for filtering.

In this embodiment, by adjusting the equivalent resistance of the maximum power point tracking module 102 so that the equivalent resistance of the maximum power point tracking module 102 is always equal to the internal resistance of the photovoltaic module PV, the maximum power of the photovoltaic module PV can be achieved. output.

In another embodiment, as shown in FIG. 10 , the input power supply 200 of the inverter 1000 includes a battery BAT, and the inverter 1000 further includes a DC-DC converter module 103 . Among them, the DC-DC converter module 103 is connected to the battery BAT, the positive bus capacitor C1 and the negative bus capacitor C2 respectively.

Specifically, the DC-DC converter module 103 is used to convert the voltage output by the battery BAT into a first DC voltage, and input it to the positive bus capacitor C1 and the negative bus capacitor C2. The DC-DC converter module 103 is used to convert one DC voltage into another DC voltage. The DC-DC converter module 103 is usually composed of inductors, capacitors, power switch tubes and other components, and achieves precise regulation of the output voltage by adjusting and switching the input voltage. The DC-DC converter module 103 has a variety of different working modes, such as buck type, boost type, etc., which can be selected according to the needs of the application scenario.

Please refer to FIG. 11 , which exemplarily shows a circuit structure of the DC-DC converter module 103 .

As shown in Figure 11, the DC-DC converter module 103 includes a third inductor L3, a third switch Q3, a fourth switch Q4, a fifth switch Q5, a sixth switch Q6, a sixth capacitor C6, a seventh Capacitor C7 and eighth capacitor C8.

Among them, the first end of the third inductor L3 is connected to the photovoltaic module PV, and the second end of the third inductor L3 is connected to the second end of the fourth switching tube Q4 and the third end of the fifth switching tube Q5 respectively. The first end of the transistor Q3, the first end of the fourth switching transistor Q4, the first end of the fifth switching transistor Q5 and the first end of the sixth switching transistor Q6 are all connected to the controller 11, and the first end of the fifth switching transistor Q5 The two terminals are respectively connected to the third terminal of the sixth switching tube Q6 and the second terminal of the sixth capacitor C6. The second terminal of the sixth switching tube Q6 is respectively connected to the second terminal of the negative bus capacitor C2 and the third terminal of the seventh capacitor C7. Two terminals are connected, the third terminal of the fourth switching tube Q4 is connected to the second terminal of the third switching tube Q3 and the first terminal of the sixth capacitor C6 respectively, and the third terminal of the third switching tube Q3 is respectively connected to the positive bus capacitor C1 is connected to the first end of the seventh capacitor C7, and the eighth capacitor C8 and the seventh capacitor C7 are connected in parallel.

Specifically, when the fifth switching tube Q5 and the third switching tube Q3 are driven to be turned on and the fourth switching tube Q4 and the sixth switching tube Q6 are turned off, the battery BAT, the third inductor L3, the sixth capacitor C6 and the The three switching tubes Q5 form a loop; when the fifth switching tube Q5 and the sixth switching tube Q6 are driven to conduct, and the third switching tube Q3 and the fourth switching tube Q4 are turned off, the battery BAT, the fifth switching tube Q5, and the fourth switching tube Q5 are turned off. Six switching tubes Q6 form a loop. When the third switching tube Q3 and the fourth switching tube Q4 are driven to be turned on and the fifth switching tube Q5 and the sixth switching tube Q6 are turned off, the battery BAT, the third switching tube Q3 and the fourth switching tube Q4 form a loop; When the fourth switching tube Q4 and the sixth switching tube Q6 are driven to be turned on, and the fifth switching tube Q5 and the third switching tube Q3 are turned off, the battery BAT, the fourth switching tube Q4, the sixth capacitor C6, the sixth switch Pipe Q6 forms a loop.

Among them, the seventh capacitor C7 and the eighth capacitor C8 are both used for filtering.

In one embodiment, as shown in FIG. 12 , the input power supply 200 may also include a photovoltaic component PV and a battery BAT. At this time, the inverter 1000 may include a maximum power point tracking module 102 and a DC-DC converter module 103 at the same time.

Among them, the photovoltaic module PV and the battery BAT can provide power at the same time or separately, and the embodiments of this application do not impose specific restrictions on this. For the specific implementation process of this embodiment, reference can be made to the detailed description of FIG. 8 and FIG. 10 , which will not be described again here.

An embodiment of the present application also provides an energy storage system, which includes an input power supply, a load, and the inverter 1000 in any embodiment of the present application.

In some embodiments, the input power source includes photovoltaic modules, and/or batteries. Then the load includes electrical equipment and/or the power grid.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application, but not to limit it; under the idea of the present application, the technical features of the above embodiments or different embodiments can also be combined. The steps may be performed in any order, and there are many other variations of different aspects of the application as described above, which are not provided in detail for the sake of brevity; although the application has been described in detail with reference to the foregoing embodiments, one of ordinary skill in the art Skilled persons should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not deviate from the essence of the corresponding technical solutions from the implementation of the present application. Example scope of technical solutions.

Claims (11)

1. A bus bar midpoint balancing circuit, comprising:

the positive bus capacitor is connected with the negative bus capacitor in series, and two ends of a circuit formed by connecting the positive bus capacitor with the negative bus capacitor in series are connected with an input power supply;

the voltage balancing module is respectively connected with the positive bus capacitor and the negative bus capacitor, and is used for controlling the positive bus capacitor to discharge or controlling the negative bus capacitor to charge so as to reduce a first difference value between the voltage of the positive bus capacitor and the voltage of the negative bus capacitor, or controlling the negative bus capacitor to discharge or controlling the positive bus capacitor to charge so as to increase the first difference value.

2. The bus bar midpoint balancing circuit of claim 1, wherein the voltage balancing module comprises a controller, a switching leg, and an impedance leg;

the controller is respectively connected with the positive bus capacitor and the negative bus capacitor, and is used for acquiring a first voltage of the positive bus capacitor and a second voltage of the negative bus capacitor and outputting a first control signal or a second control signal based on the first voltage and the second voltage;

the switch branch is respectively connected with the controller, the impedance branch, the positive bus capacitor and the negative bus capacitor, and is used for responding to the first control signal to be in a first conduction state so that the positive bus capacitor is discharged through the impedance branch and the negative bus capacitor is charged through the impedance branch, or is used for responding to the second control signal to be in a second conduction state so that the negative bus capacitor is discharged through the impedance branch and the positive bus capacitor is charged through the impedance branch.

3. The bus bar midpoint balancing circuit of claim 2, wherein the switch leg comprises a first switch and a second switch;

the first switch is respectively connected with the second switch, the positive bus capacitor and the impedance branch, and the second switch is respectively connected with the negative bus capacitor and the impedance branch;

when the first switch is turned on in response to the first control signal and the second switch is turned off, the switch branch is in a first conduction state;

the switching branch is in a second conductive state when the second switch is turned on in response to the second control signal and the first switch is turned off.

4. The bus midpoint balancing circuit according to claim 3, wherein the control terminal of the first switch and the control terminal of the second switch are connected to the controller, the first terminal of the first switch is connected to the first terminal of the positive bus capacitor, the second terminal of the first switch is connected to the first terminal of the second switch and the first terminal of the impedance branch, the second terminal of the impedance branch is connected to the second terminal of the positive bus capacitor and the first terminal of the negative bus capacitor, respectively, and the second terminal of the second switch is connected to the second terminal of the negative bus capacitor.

5. The bus bar midpoint balanced circuit of claim 2, wherein the impedance branch comprises a first inductance;

the first end of the first inductor is connected with the switch branch, and the second end of the first inductor is connected with the positive bus capacitor and the negative bus capacitor respectively.

6. The bus bar midpoint balanced circuit of claim 2, wherein the impedance branch comprises a first resistor;

the first end of the first resistor is connected with the switch branch, and the second end of the first resistor is connected with the positive bus capacitor and the negative bus capacitor respectively.

7. An inverter comprising an inverter module and a bus neutral point balancing circuit as claimed in any one of claims 1 to 6;

the inversion module is respectively connected with the positive bus capacitor, the negative bus capacitor and the load, and is used for converting the voltage between the positive bus capacitor and the negative bus capacitor into first alternating voltage and supplying power to the load based on the first alternating voltage.

8. The inverter of claim 7, wherein the input power source of the inverter comprises a photovoltaic module, the inverter further comprising a maximum power point tracking module;

the maximum power point tracking module is respectively connected with the photovoltaic module, the positive bus capacitor and the negative bus capacitor, and is used for keeping the photovoltaic module to output maximum power to the positive bus capacitor and the negative bus capacitor.

9. The inverter of claim 7, wherein the input power source of the inverter comprises a battery, the inverter further comprising a dc-to-dc converter module;

the direct current-direct current converter module is respectively connected with the battery, the positive bus capacitor and the negative bus capacitor, and is used for converting the voltage output by the battery into a first direct current voltage and inputting the first direct current voltage to the positive bus capacitor and the negative bus capacitor.

10. An energy storage system comprising an input power source, a load and an inverter as claimed in any one of claims 7 to 9.

11. The energy storage system of claim 10, wherein the input power source comprises a photovoltaic module, and/or a battery;

the load comprises a consumer, and/or a power grid.