A pre-charging circuit for an anti-backflow energy storage system

Abstract

This utility model discloses a pre-charging circuit for an anti-backflow energy storage system, including an energy storage system power supply terminal, an inverter module, and a pre-charging control module. One end of the energy storage system power supply terminal is connected to the inverter module, and the other end is connected to the pre-charging control module. The other end of the inverter module is connected to the pre-charging control module. The pre-charging control module includes at least two MOSFETs connected in series, with their sources or drains connected together. The turn-on and turn-off signals of the two MOSFETs are identical. When the pre-charging control module turns on the two MOSFETs, the current from the energy storage system power supply terminal flows to the inverter module. When the pre-charging control module turns off the two MOSFETs, the current from the inverter module cannot flow to the energy storage system power supply terminal. This anti-backflow energy storage system pre-charging circuit can safely and reliably prevent the inverter from inputting reverse current to the battery.

Description

Technical Field

[0001] This application belongs to the field of energy storage system technology, specifically referring to a pre-charging circuit for an anti-backflow energy storage system. Background Technology

[0002] In existing energy storage systems, these systems are typically used in conjunction with energy storage inverters. These inverters have numerous bus capacitors on the battery input side (typically configured for 63-100V, with a maximum of 127mF), which are fully charged during operation. When the energy storage system is shut down for a period of time, these bus capacitors gradually discharge due to self-discharge. The moment power is switched on, these empty capacitors are equivalent to a short circuit, posing a significant safety hazard to the energy storage system. Therefore, conventional designs usually require a pre-charging circuit, incorporating a resistor in series to reduce the charging current during pre-charging.

[0003] While this conventional circuit design can solve the problem of pre-charging the capacitor at the moment of inverter power-on, the following problems exist in actual use: 1. Many energy storage inverters often open a high BUS terminal voltage when the battery is not connected. When the battery is connected, the reverse current brought by this voltage will have a significant impact on the battery and switching devices, leading to a decrease in battery life or damage to the devices; 2. When the energy storage inverter is connected to an inductive load (such as an AC asynchronous motor), the sudden stop of the motor will bring a high reverse induced voltage (the value may be very high, possibly several hundred volts or more) to the main bus BUS. This voltage will cause a strong withstand voltage surge to the switching devices on the line, and long-term use can easily damage the switching devices. Utility Model Content

[0004] To overcome the shortcomings of the prior art, this application provides a pre-charging circuit for an anti-backflow energy storage system, which can safely and reliably prevent the inverter from inputting backflow current to the battery.

[0005] This utility model provides a pre-charging circuit for an anti-backflow energy storage system, including an energy storage system power supply terminal, an inverter module, and a pre-charging control module; one end of the energy storage system power supply terminal is connected to the inverter module, and the other end is connected to the pre-charging control module; the other end of the inverter module is connected to the pre-charging control module.

[0006] The precharge control module includes at least two MOSFETs connected in series, with their sources or drains connected together, and the turn-on and turn-off signals of the two MOSFETs being the same.

[0007] When the pre-charge control module turns on the two MOSFETs, the current from the power supply terminal of the energy storage system flows to the inverter module; when the pre-charge control module turns off the two MOSFETs, the current from the inverter module cannot flow to the power supply terminal of the energy storage system.

[0008] Furthermore, according to the backflow prevention energy storage system pre-charging circuit provided in this application, the power supply terminal of the energy storage system includes a battery and a pre-charging resistor RX1; the positive terminal BAT+ of the battery is connected to the positive terminal BUS+ of the inverter module, the negative terminal BAT- of the battery is connected to the negative terminal BUS- of the inverter module, and the pre-charging resistor RX1 is connected between the negative terminal BUS- of the inverter module and the negative terminal BAT- of the battery.

[0009] Furthermore, according to the backflow prevention energy storage system pre-charging circuit provided in this application, the inverter module includes at least a first capacitor C1, a second capacitor C2, a third capacitor C3, and an inverter F21;

[0010] The first capacitor C1, the second capacitor C2, and the third capacitor C3 are connected in parallel. One end of the parallel connection of the first capacitor C1, the second capacitor C2, and the third capacitor C3 is connected to the positive terminal BUS+ of the inverter module, and the other end is connected to the negative terminal BUS- of the inverter module. The inverter F21 is connected to the negative terminal BUS- of the inverter module and the pre-charge resistor RX1.

[0011] Furthermore, according to the backflow prevention energy storage system pre-charging circuit provided in this application, the pre-charging control module includes a microcontroller, a first MOSFET Q1, and a second MOSFET Q2;

[0012] The gates of the first MOSFET Q1 and the second MOSFET Q2 are both connected to the control terminal of the microcontroller. The first MOSFET Q1 receives the PDgate control signal from the microcontroller, and the second MOSFET Q2 receives the PCgate control signal from the microcontroller. They are controlled by the microcontroller to turn on or off. The conduction currents of the first MOSFET Q1 and the second MOSFET Q2 are in opposite directions.

[0013] Furthermore, according to the backflow prevention energy storage system pre-charging circuit provided in this application, the first MOSFET Q1 and the second MOSFET Q2 are NMOS transistors;

[0014] The source of the first MOSFET Q1 is connected to the negative terminal BAT- of the battery, the drain of the first MOSFET Q1 is connected to the drain of the second MOSFET Q2, and the source of the second MOSFET Q2 is connected to the pre-charge resistor RX1.

[0015] When the first MOSFET Q1 and the second MOSFET Q2 are turned on, the current flows from the power supply terminal of the energy storage system to the inverter module, and then returns to the power supply terminal of the energy storage system via the pre-charge control module to complete the pre-charge; when the first MOSFET Q1 and the second MOSFET Q2 are turned off, the reverse current of the inverter module cannot turn on the first MOSFET Q1 and the second MOSFET Q2.

[0016] Furthermore, according to the backflow prevention energy storage system pre-charging circuit provided in this application, the first MOSFET Q1 and the second MOSFET Q2 are PMOS transistors;

[0017] The drain of the first MOSFET Q1 is connected to the negative terminal BAT- of the battery, the source of the first MOSFET Q1 is connected to the source of the second MOSFET Q2, and the drain of the second MOSFET Q2 is connected to the pre-charge resistor RX1.

[0018] When the first MOSFET Q1 and the second MOSFET Q2 are turned on, the current flows from the power supply terminal of the energy storage system to the inverter module, and then returns to the power supply terminal of the energy storage system via the pre-charge control module to complete the pre-charge; when the first MOSFET Q1 and the second MOSFET Q2 are turned off, the reverse current of the inverter module cannot turn on the first MOSFET Q1 and the second MOSFET Q2.

[0019] Furthermore, according to the backflow prevention energy storage system pre-charging circuit provided in this application, the pre-charging control module also includes a first resistor R1 and a second resistor R2;

[0020] One end of the first resistor R1 is connected to the control terminal of the microcontroller, and the other end of the first resistor R1 is connected to the gate of the first MOSFET Q1; one end of the second resistor R2 is connected to the gate of the first MOSFET Q1, and the other end of the second resistor R2 is connected to the source of the first MOSFET Q1.

[0021] The first resistor R1, the second resistor R2, and the first MOSFET Q1 constitute the first control unit.

[0022] Furthermore, according to the backflow prevention energy storage system pre-charging circuit provided in this application, the pre-charging control module also includes a third resistor R3, a fourth resistor R4, and a Zener diode ZD1;

[0023] One end of the third resistor R3 is connected to the control terminal of the microcontroller, and the other end of the third resistor R3 is connected to the gate of the second MOSFET Q2; one end of the fourth resistor R4 is connected to the gate of the second MOSFET Q2, and the other end of the fourth resistor R4 is connected to the source of the second MOSFET Q2; one end of the Zener diode ZD1 is connected to the gate of the second MOSFET Q2, and the other end of the Zener diode ZD1 is connected to the source of the second MOSFET Q2.

[0024] The first resistor R1, the second resistor R2, the Zener diode ZD1, and the second MOSFET Q2 constitute the second control unit.

[0025] The beneficial effects of this utility model are as follows: According to the pre-charging circuit of the anti-backflow energy storage system provided in this application, two MOSFETs are connected in series, with their sources or drains connected together. The turn-on and turn-off signals of the two MOSFETs are the same. When the two MOSFETs are turned on, the power supply terminal of the energy storage system can normally pre-charge the inverter module. After pre-charging is completed, the two MOSFETs are turned off synchronously. Since the sources or drains of the two MOSFETs are connected together, the direction of the conduction current is opposite. Therefore, the reverse current from the inverter module cannot turn on the two MOSFETs, and the inverter module cannot input reverse current. This can safely and reliably prevent the inverter from inputting reverse current to the battery, thereby improving the safety of the system. Attached Figure Description

[0026] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0027] Figure 1 This is a pre-charging circuit for energy storage systems in the prior art.

[0028] Figure 2 This is a schematic block diagram of the pre-charging circuit of the anti-backflow energy storage system provided in this embodiment.

[0029] Figure 3 This is a schematic diagram of the pre-charging circuit of the anti-backflow energy storage system provided in this embodiment.

[0030] The components in the diagram are labeled as follows: Energy storage system power supply 10, inverter module 20, pre-charge control module 30. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0032] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0034] The embodiments of this application will now be further described in conjunction with the accompanying drawings and specific implementation details.

[0035] Figure 1 This is a pre-charging circuit for energy storage systems in the prior art.

[0036] like Figure 1As shown, in the existing pre-charging circuit of the energy storage system, the pre-charging circuit is activated first after the battery is powered on. The PDgate signal output by the microcontroller of the pre-charging circuit is at a high level, at which time the NMOS transistor Q1 is turned on. The battery charges the inverter bus capacitors C1, C2, and C3 through the pre-charging resistor RX1. At this time, the current direction is from the battery positive terminal BAT+ to the inverter positive terminal BUS+, then to the inverter bus capacitors C1, C2, and C3, then to the inverter negative terminal BUS-, then to the inverter F21, then to the pre-charging resistor RX1, and finally back to the battery negative terminal BAT- through the MOSFET Q1. After charging is completed, the main circuit is switched.

[0037] like Figure 1 The pre-charge circuit shown can solve the problem of current limiting during pre-charge, but the inverter may have a reverse current problem. Figure 1 In addition, there is a reverse current from the inverter. The reverse current is as follows: from the positive terminal BUS+ of the inverter to the positive terminal BAT+ of the battery, then to the negative terminal BAT- of the battery, then through the MOSFET Q1, then through the pre-charge resistor RX1, through the inverter F21, and finally back to the negative terminal BUS- of the inverter, thus forming a reverse current loop. Figure 1 The pre-charge circuit shown cannot solve the problem of inverter backflow current to the battery.

[0038] Therefore, this embodiment provides a pre-charging circuit for an anti-backflow energy storage system, which can solve the problem of inverter backflow current supplying the battery.

[0039] Figure 2 This is a schematic block diagram of the pre-charging circuit of the anti-backflow energy storage system provided in this embodiment.

[0040] like Figure 2 As shown, the backflow prevention energy storage system pre-charging circuit provided in this embodiment includes an energy storage system power supply terminal 10, an inverter module 20, and a pre-charging control module 30. One end of the energy storage system power supply terminal 10 is connected to the inverter module 20, and the other end is connected to the pre-charging control module 30. The other end of the inverter module 20 is connected to the pre-charging control module 30. The pre-charging control module 30 includes at least two MOSFETs connected in series. The sources or drains of the two MOSFETs are connected together, and the turn-on and turn-off signals of the two MOSFETs are the same. The conduction currents of the two MOSFETs are in opposite directions. After the pre-charging control module 30 controls the two MOSFETs to turn on, the current in the energy storage system power supply terminal 10 flows to the inverter module 20. After the pre-charging control module 30 controls the two MOSFETs to turn off, the current in the inverter module 20 cannot flow to the energy storage system power supply terminal 10.

[0041] Specifically, since the conduction currents of the two MOSFETs are in opposite directions, after the circuit pre-charge is completed and the two MOSFETs are turned off, even if the inverter module 20 generates a reverse current, the reverse current can only turn on one of the MOSFETs and cannot turn on both MOSFETs at the same time. Therefore, a current loop cannot be formed between the energy storage system power supply terminal 10, the inverter module 20, and the pre-charge control module 30, thus preventing the reverse current of the inverter module 20 from flowing into the energy storage system power supply terminal 10.

[0042] Figure 3 This is a schematic diagram of the pre-charging circuit of the anti-backflow energy storage system provided in this embodiment.

[0043] like Figure 3 As shown, in this embodiment, the power supply terminal 10 of the energy storage system includes a battery and a pre-charge resistor RX1; the positive terminal BAT+ of the battery is connected to the positive terminal BUS+ of the inverter module 20, the negative terminal BAT- of the battery is connected to the negative terminal BUS- of the inverter module 20, and the pre-charge resistor RX1 is connected between the negative terminal BUS- of the inverter module 20 and the negative terminal BAT- of the battery.

[0044] The inverter module 20 includes at least a first capacitor C1, a second capacitor C2, a third capacitor C3, and an inverter F21; wherein the first capacitor C1, the second capacitor C2, and the third capacitor C3 are generally configured to be 63-100V, and the maximum capacity can reach 127mF.

[0045] The first capacitor C1, the second capacitor C2, and the third capacitor C3 are connected in parallel. One end of the parallel connection of the first capacitor C1, the second capacitor C2, and the third capacitor C3 is connected to the positive terminal BUS+ of the inverter module 20, and the other end is connected to the negative terminal BUS- of the inverter module 20. The inverter F21 is connected to the negative terminal BUS- of the inverter module 20 and the pre-charge resistor RX1.

[0046] The pre-charge control module 30 includes a microcontroller, a first MOSFET Q1, and a second MOSFET Q2;

[0047] The gates of the first MOSFET Q1 and the second MOSFET Q2 are both connected to the control terminal of the microcontroller. The first MOSFET Q1 receives the PDgate control signal from the microcontroller, and the second MOSFET Q2 receives the PCgate control signal from the microcontroller. They are controlled by the microcontroller to turn on or off. The conduction currents of the first MOSFET Q1 and the second MOSFET Q2 are in opposite directions.

[0048] In this embodiment, the first MOS transistor Q1 and the second MOS transistor Q2 are NMOS transistors for illustration.

[0049] The source of the first MOSFET Q1 is connected to the negative terminal BAT- of the battery, the drain of the first MOSFET Q1 is connected to the drain of the second MOSFET Q2, and the source of the second MOSFET Q2 is connected to the pre-charge resistor RX1; the other end of the pre-charge resistor RX1 is connected to the inverter F21.

[0050] When the first MOSFET Q1 and the second MOSFET Q2 are turned on, the current flows from the power supply terminal 10 of the energy storage system to the inverter module 20, and then returns to the power supply terminal 10 of the energy storage system via the pre-charge control module 30 to complete the pre-charge; when the first MOSFET Q1 and the second MOSFET Q2 are turned off, the reverse current of the inverter module 20 cannot turn on the first MOSFET Q1 and the second MOSFET Q2.

[0051] like Figure 3 As shown, in this embodiment, the pre-charge control module 30 further includes a first resistor R1 and a second resistor R2; one end of the first resistor R1 is connected to the control terminal of the microcontroller, and the other end of the first resistor R1 is connected to the gate of the first MOS transistor Q1; one end of the second resistor R2 is connected to the gate of the first MOS transistor Q1, and the other end of the second resistor R2 is connected to the source of the first MOS transistor Q1; the first resistor R1, the second resistor R2, and the first MOS transistor Q1 constitute the first control unit.

[0052] The pre-charge control module 30 also includes a third resistor R3, a fourth resistor R4, and a Zener diode ZD1; one end of the third resistor R3 is connected to the control terminal of the microcontroller, and the other end of the third resistor R3 is connected to the gate of the second MOSFET Q2; one end of the fourth resistor R4 is connected to the gate of the second MOSFET Q2, and the other end of the fourth resistor R4 is connected to the source of the second MOSFET Q2; one end of the Zener diode ZD1 is connected to the gate of the second MOSFET Q2, and the other end of the Zener diode ZD1 is connected to the source of the second MOSFET Q2; the first resistor R1, the second resistor R2, the Zener diode ZD1, and the second MOSFET Q2 constitute a second control unit.

[0053] In this embodiment, a second MOSFET Q2 connected in series is added to the pre-charge control module 30. When the inverter module 20 is pre-charging, both the first MOSFET Q1 and the second MOSFET Q2 are turned on simultaneously, and the energy storage system power supply terminal 10 pre-charges the inverter module 20. After pre-charging is completed, both the first MOSFET Q1 and the second MOSFET Q2 are turned off simultaneously.

[0054] The working principle of the pre-charging circuit of the anti-backflow energy storage system provided in this embodiment is as follows:

[0055] After the battery at the power supply terminal 10 of the energy storage system is powered on, the pre-charging circuit of the inverter module 20 is first turned on. The microcontroller in the pre-charging control module 30 controls the PDgate control signal and the PCgate control signal to be at a high level at the same time. At this time, the first MOS transistor Q1 and the second MOS transistor Q2, which are both NMOS transistors, are turned on. The battery at the power supply terminal 10 of the energy storage system charges the bus capacitors in the inverter module 20, namely the first capacitor C1, the second capacitor C2 and the third capacitor C3, through the pre-charging resistor RX1.

[0056] At this time, the current direction is: from the positive terminal BAT+ of the battery to the positive terminal BUS+ of the inverter, to the first capacitor C1, the second capacitor C2, the third capacitor C3 of the inverter, then to the negative terminal BUS- of the inverter, then to F21 of the inverter, to the pre-charge resistor RX1, and then back to the negative terminal BAT- of the battery through the first MOSFET Q1 and the second MOSFET Q2.

[0057] At this point, after charging is complete, the main circuit is switched, and the microcontroller simultaneously controls the shutdown of the first MOSFET Q1 and the second MOSFET Q2.

[0058] When pre-charging is turned off, since the second MOSFET Q2 is already turned off, even if the main bus of the inverter module 20 has a high voltage, the reverse current of the inverter cannot turn on the second MOSFET Q2, so the inverter cannot reverse current to the battery.

[0059] Specifically, in another embodiment, the first MOSFET Q1 and the second MOSFET Q2 are PMOS transistors; the drain of the first MOSFET Q1 is connected to the negative terminal BAT- of the battery, the source of the first MOSFET Q1 is connected to the source of the second MOSFET Q2, and the drain of the second MOSFET Q2 is connected to the pre-charge resistor RX1; after the first MOSFET Q1 and the second MOSFET Q2 are turned on, the current flows from the power supply terminal 10 of the energy storage system to the inverter module 20, and then returns to the power supply terminal 10 of the energy storage system via the pre-charge control module 30 to complete the pre-charge; after the first MOSFET Q1 and the second MOSFET Q2 are turned off, the reverse current of the inverter module 20 cannot turn on the first MOSFET Q1 and the second MOSFET Q2.

[0060] The conduction levels of PMOS and NMOS transistors are opposite, and other settings are adjusted accordingly. The working principle is the same, so it will not be elaborated here.

[0061] The backflow prevention energy storage system pre-charging circuit provided in this application uses two MOSFETs connected in series, with their sources or drains connected together. The turn-on and turn-off signals of the two MOSFETs are identical. When both MOSFETs are on, the energy storage system power supply terminal 10 can normally pre-charge the inverter module 20. After pre-charging, the two MOSFETs are simultaneously turned off. Because the sources or drains of the two MOSFETs are connected, the direction of the conduction current is opposite. Therefore, the backflow current from the inverter module 20 cannot turn on the two MOSFETs, and the inverter module 20 cannot input backflow current. This safely and reliably prevents the inverter from inputting backflow current to the battery, thereby improving system safety.

[0062] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the present invention. Finally, it should be noted that in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0063] The foregoing has provided a detailed description of a pre-charging circuit for an anti-backflow energy storage system according to the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A pre-charging circuit for an anti-backflow energy storage system, characterized in that, It includes an energy storage system power supply terminal, an inverter module, and a pre-charge control module; one end of the energy storage system power supply terminal is connected to the inverter module, and the other end is connected to the pre-charge control module; the other end of the inverter module is connected to the pre-charge control module. The precharge control module includes at least two MOSFETs connected in series, with their sources or drains connected together, and the turn-on and turn-off signals of the two MOSFETs being the same. When the pre-charge control module turns on the two MOSFETs, the current from the power supply terminal of the energy storage system flows to the inverter module; when the pre-charge control module turns off the two MOSFETs, the current from the inverter module cannot flow to the power supply terminal of the energy storage system.

2. The backflow prevention energy storage system pre-charge circuit of claim 1, wherein The power supply terminal of the energy storage system includes a battery and a pre-charge resistor RX1; the positive terminal BAT+ of the battery is connected to the positive terminal BUS+ of the inverter module, the negative terminal BAT- of the battery is connected to the negative terminal BUS- of the inverter module, and the pre-charge resistor RX1 is connected between the negative terminal BUS- of the inverter module and the negative terminal BAT- of the battery.

3. The pre-charging circuit of the anti-backflow energy storage system according to claim 2, characterized in that, The inverter module includes at least a first capacitor C1, a second capacitor C2, a third capacitor C3, and an inverter F21; The first capacitor C1, the second capacitor C2, and the third capacitor C3 are connected in parallel. One end of the parallel connection of the first capacitor C1, the second capacitor C2, and the third capacitor C3 is connected to the positive terminal BUS+ of the inverter module, and the other end is connected to the negative terminal BUS- of the inverter module. The inverter F21 is connected to the negative terminal BUS- of the inverter module and the pre-charge resistor RX1.

4. The backflow prevention energy storage system pre-charge circuit of claim 3, wherein, The pre-charge control module includes a microcontroller, a first MOSFET Q1, and a second MOSFET Q2; The gates of the first MOSFET Q1 and the second MOSFET Q2 are both connected to the control terminal of the microcontroller. The first MOSFET Q1 receives the PDgate control signal from the microcontroller, and the second MOSFET Q2 receives the PCgate control signal from the microcontroller. They are controlled by the microcontroller to turn on or off. The conduction currents of the first MOSFET Q1 and the second MOSFET Q2 are in opposite directions.

5. The backflow prevention energy storage system pre-charge circuit of claim 4, wherein, The first MOSFET Q1 and the second MOSFET Q2 are NMOS transistors; The source of the first MOSFET Q1 is connected to the negative terminal BAT- of the battery, the drain of the first MOSFET Q1 is connected to the drain of the second MOSFET Q2, and the source of the second MOSFET Q2 is connected to the pre-charge resistor RX1. When the first MOSFET Q1 and the second MOSFET Q2 are turned on, the current flows from the power supply terminal of the energy storage system to the inverter module, and then returns to the power supply terminal of the energy storage system via the pre-charge control module to complete the pre-charge; when the first MOSFET Q1 and the second MOSFET Q2 are turned off, the reverse current of the inverter module cannot turn on the first MOSFET Q1 and the second MOSFET Q2.

6. The backflow prevention energy storage system pre-charge circuit of claim 4, wherein, The first MOSFET Q1 and the second MOSFET Q2 are PMOS transistors; The drain of the first MOSFET Q1 is connected to the negative terminal BAT- of the battery, the source of the first MOSFET Q1 is connected to the source of the second MOSFET Q2, and the drain of the second MOSFET Q2 is connected to the pre-charge resistor RX1. When the first MOSFET Q1 and the second MOSFET Q2 are turned on, the current flows from the power supply terminal of the energy storage system to the inverter module, and then returns to the power supply terminal of the energy storage system via the pre-charge control module to complete the pre-charge; when the first MOSFET Q1 and the second MOSFET Q2 are turned off, the reverse current of the inverter module cannot turn on the first MOSFET Q1 and the second MOSFET Q2.

7. The backflow preventing energy storage system pre-charge circuit of any one of claims 4 to 6, wherein, The pre-charge control module also includes a first resistor R1 and a second resistor R2; One end of the first resistor R1 is connected to the control terminal of the microcontroller, and the other end of the first resistor R1 is connected to the gate of the first MOSFET Q1; one end of the second resistor R2 is connected to the gate of the first MOSFET Q1, and the other end of the second resistor R2 is connected to the source of the first MOSFET Q1. The first resistor R1, the second resistor R2, and the first MOSFET Q1 constitute the first control unit.

8. The backflow prevention energy storage system pre-charge circuit of claim 7, wherein, The pre-charge control module also includes a third resistor R3, a fourth resistor R4, and a Zener diode ZD1; One end of the third resistor R3 is connected to the control terminal of the microcontroller, and the other end of the third resistor R3 is connected to the gate of the second MOSFET Q2; one end of the fourth resistor R4 is connected to the gate of the second MOSFET Q2, and the other end of the fourth resistor R4 is connected to the source of the second MOSFET Q2; one end of the Zener diode ZD1 is connected to the gate of the second MOSFET Q2, and the other end of the Zener diode ZD1 is connected to the source of the second MOSFET Q2. The first resistor R1, the second resistor R2, the Zener diode ZD1, and the second MOSFET Q2 constitute the second control unit.

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