A circuit for reducing leakage current in a photovoltaic energy storage system

Abstract

The utility model discloses a kind of circuit for reducing leakage current of photovoltaic energy storage system, including PV charging module, inverter main power module, output module and commercial power module, also including reduce leakage current circuit;The input end of the inverter main power module is connected with the output end of the PV charging module, the input end of the reduce leakage current circuit is connected with the output end of the inverter main power module, the output end of the reduce leakage current circuit is connected with the input end of the output module, the input end of the commercial power module, the commercial power module is used for the access or disconnection of commercial power, output module is used for output alternating current, power supply for alternating current load.The utility model uses reduce leakage current circuit, so that common-mode voltage generated by photovoltaic panel negative end to power grid N line is greatly reduced, the leakage current of its corresponding inverter full bridge is reduced, thereby can effectively reduce leakage current on photovoltaic energy storage system.

Description

Technical Field

[0001] This utility model relates to the field of power electronics, and in particular to a circuit for reducing leakage current in a photovoltaic energy storage system. Background Technology

[0002] Currently, when photovoltaic energy storage systems are fed into the grid, there is a large leakage current between the grid neutral line (grid neutral line, grid N line) and the ground. This leakage current can cause protection malfunctions, equipment damage, increased losses, and may even lead to personal safety issues. Utility Model Content

[0003] The purpose of this invention is to provide a circuit that reduces leakage current in a photovoltaic energy storage system to solve the aforementioned problems in the prior art.

[0004] First, this utility model provides a circuit for reducing leakage current in a photovoltaic energy storage system, including a PV charging module, an inverter main power module, an output module, and a mains power module. The key feature is that it further includes a leakage current reduction circuit. The input terminal of the inverter main power module is connected to the output terminal of the PV charging module, the input terminal of the leakage current reduction circuit is connected to the output terminal of the inverter main power module, and the output terminal of the leakage current reduction circuit is connected to the input terminal of the output module and the input terminal of the mains power module. The mains power module is used for connecting or disconnecting mains power, and the output module is used for outputting AC power to supply AC loads. The leakage current reduction circuit includes a fourth capacitor, a fifth capacitor, a first resistor, a second diode, and a third diode. One end of the fourth capacitor and the cathode of the second diode are connected to the first output terminal of the inverter main power module. The cathode of the third diode and one end of the fifth capacitor are connected to the second output terminal of the inverter main power module. The anode of the second diode and the anode of the third diode are connected to one end of the first resistor. The other end of the fourth capacitor, the other end of the fifth capacitor, and the other end of the first resistor are connected to the third output terminal of the inverter main power module, which is also the negative terminal of the PV DC power supply of the PV charging module. The first and second output terminals of the leakage current reduction circuit are the first and second output terminals of the inverter main power module, respectively.

[0005] Furthermore, the PV charging module is a boost module, a buck module, or a buck-boost module.

[0006] Furthermore, the main power inverter module can be a full-bridge inverter module, a half-bridge inverter module, an I-shaped inverter module, or a T-shaped inverter module.

[0007] Furthermore, it also includes a chip control module, the output of which is connected to the switch control terminals of the PV charging module, the inverter main power module, the output module, and the mains power module, respectively, for sending control signals to control the on / off state of the corresponding switches.

[0008] Furthermore, the switches in the PV charging module and the inverter main power module are transistors, MOSFETs, or IGBTs.

[0009] Furthermore, the switches in the output module and the mains power module are relays.

[0010] Furthermore, the mains power module includes two relays, namely a second relay and a third relay. One end of the second relay and one end of the third relay are respectively the first input terminal and the second input terminal of the mains power module, which are respectively connected to the first output terminal and the second output terminal of the leakage current reduction circuit. The other end of the second relay and one end of the third relay are respectively the first output terminal and the second output terminal of the mains power module, which are respectively connected to the mains live wire and the mains neutral wire.

[0011] Furthermore, the output module includes a seventh capacitor, a fifth inductor, an eighth capacitor, and a first relay; the two ends of the seventh capacitor are the input terminals of the output module, respectively connected to the first output terminal and the second output terminal of the leakage current reduction circuit; the fifth inductor is a common-mode inductor, including a first winding and a second winding, the first end of the first winding is connected to one end of the seventh capacitor, the second end of the first winding is connected to one end of the eighth capacitor and one end of the first relay, the other end of the first relay is connected to one end of the AC load, the first end of the second winding is connected to the other end of the seventh capacitor, and the second end of the second winding is connected to the other end of the eighth capacitor and the other end of the AC load.

[0012] Furthermore, the second diode and the third diode are freewheeling diodes.

[0013] Furthermore, the first resistor is a cement resistor.

[0014] The circuit of this utility model for reducing leakage current in photovoltaic energy storage system adopts a leakage current reduction circuit, which significantly reduces the common-mode voltage generated by the negative terminal of the photovoltaic panel to the N line of the power grid, and the corresponding leakage current of the inverter full bridge is reduced, thereby effectively reducing the leakage current in the photovoltaic energy storage system. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a circuit for reducing leakage current in a photovoltaic energy storage system according to one embodiment of the present invention. Figure 2This is a circuit diagram of a circuit for reducing leakage current in a photovoltaic energy storage system according to another embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram of a circuit for reducing leakage current in a photovoltaic energy storage system according to another embodiment of the present invention. Figure 4 This is a schematic diagram of a circuit for reducing leakage current in a photovoltaic energy storage system according to another embodiment of the present invention.

[0017] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this utility model. Detailed Implementation

[0018] To facilitate understanding of this utility model, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of this utility model are shown in the drawings. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this utility model will be more thorough and complete. Example

[0019] First, please see Figure 1 This embodiment provides a circuit for reducing leakage current in a photovoltaic energy storage system, which includes a PV charging module 1, an inverter main power module 2, a leakage current reduction circuit 3, an output module 4, and a mains power module 5.

[0020] The system comprises the following components: PV charging module 1 receives the DC voltage from the PV DC power supply at its input terminal and converts it into the DC voltage required by the system; inverter main power module 2 connects its input terminal to the output terminal of PV charging module 1 to receive the DC voltage output by PV charging module 1 and convert it into AC power; leakage current reduction circuit 3 suppresses leakage current, its input terminal is connected to the output terminal of inverter main power module 2, and its output terminal is connected to the input terminal of output module 4 and the input terminal of mains power module 5; output module 4 outputs AC power to supply AC loads, and mains power module 5 is used to connect or disconnect mains power, with its output terminal connected to the mains power supply (terminal).

[0021] Among them, AC loads can be AC ​​household loads, such as refrigerators, air conditioners, washing machines, lighting, etc.

[0022] In one embodiment, the circuit for reducing leakage current in the photovoltaic energy storage system further includes a chip control module 6, whose output terminal is connected to the switch control terminal of the PV charging module 1, the switch control terminal of the inverter main power module 2, the switch control terminal of the output module 4, and the switch control terminal of the mains module 5, respectively, and is used to send control signals to control the on and off (conduction and shutdown) of the switches in the PV charging module 1, the inverter main power module 2, the output module 4, and the mains module 5.

[0023] In one embodiment, the switches in both the PV charging module 1 and the inverter main power module 2 are IGBTs or MOSFETs or transistors, and the switches in both the output module 4 and the mains power module 5 are relays. For switches that are IGBTs or MOSFETs, the switch control terminal refers to the gate; for switches that are transistors, the switch control terminal refers to the base; and for switches that are relays, the switch control terminal refers to the coil terminal (one or both ends) of the relay.

[0024] Please see Figure 2 PV+ and PV- are the positive and negative terminals of the PV DC power supply, respectively, and are the two input terminals of the PV charging module 1. In other words, PV+ and PV- are the positive and negative input terminals of the PV charging module 1, respectively. The leakage current reduction circuit 3 includes a fourth capacitor C4, a fifth capacitor C5, a first resistor R1, a second diode D2, and a third diode D3. The leakage current reduction circuit 3 has three input terminals and two output terminals. One end of the fourth capacitor C4 is its first input terminal, one end of the fifth capacitor C5 is its second input terminal, and the other ends of the fourth capacitor C4, the fifth capacitor C4, and the first resistor R1 are connected together to form its third input terminal. One end of the fourth capacitor C4 (the first input terminal of the leakage current reduction circuit 3) and the cathode of the second diode D2 are connected to the inverter live wire L (the first output terminal of the inverter main power module 2). The cathode of the third diode D3 and one end of the fifth capacitor C5 (the second input terminal of the leakage current reduction circuit 3) are connected to the inverter neutral wire N (the second output terminal of the inverter main power module 2). The anodes of the second diode D2 and the third diode D3 are connected to one end of the first resistor R1. The other ends of the fourth capacitor C4, the fifth capacitor C5, and the first resistor R1 (the third input terminal of the leakage current reduction circuit 3) are connected to the negative terminal PV- of the PV DC power supply (i.e., the third output terminal of the inverter main power module 2). The cathode of the second diode D2 (i.e., the inverter live wire L) is the first output terminal of the leakage current reduction circuit 3, and the cathode of the third diode D3 (i.e., the inverter neutral wire N) is the second output terminal of the leakage current reduction circuit 3. It can be seen that the first output terminal of the leakage current reduction circuit 3 is also the first output terminal of the inverter main power module 2, and the second output terminal of the leakage current reduction circuit 3 is also the second output terminal of the inverter main power module 2. The inverter neutral wire N is connected to the ground PE.

[0025] In one embodiment, the PV DC power supply is a photovoltaic panel, the second diode D2 and the third diode D3 are both freewheeling diodes, and the first resistor is a cement resistor with a resistance value ranging from 20 to 40 ohms.

[0026] Principle of Leakage Current Suppression: When a photovoltaic energy storage system feeds into the grid, the mains power is connected. Due to the parasitic capacitance Cpg between the negative terminal PV- of the PV DC power supply and the ground PE, a common-mode voltage Upg is generated between the negative terminal PV- and the inverter neutral line N. Simultaneously, the inverter neutral line N is connected to the ground PE and the mains neutral line I / PN, resulting in a leakage current Ipg. This invention utilizes two freewheeling diodes D2 and D3 for freewheeling, and the absorption effect of resistor R1 and capacitors C4 and C5 to significantly reduce the common-mode voltage Upg. Consequently, the leakage current Ipg is reduced, thus significantly decreasing the common-mode voltage Upg generated between the negative terminal PV- of the PV DC power supply and the inverter neutral line N, and consequently reducing the leakage current Ipg.

[0027] Further, please see Figure 2 The PV charging module 1 is a boost module. In one embodiment, the boost module includes a sixth capacitor C6, a first inductor L1, a first diode D1, and a fifth switch Q5. The positive terminal of the sixth capacitor C6 and one end of the first inductor L1 are connected to the positive terminal PV+ of the PV DC power supply. The negative terminal of the sixth capacitor C6 and the current output terminal of the fifth switch Q5 are connected to the negative terminal PV- of the PV DC power supply. The other end of the first inductor L1 and the current input terminal of the fifth switch Q5 are connected to the anode of the first diode D1. The cathode of the first diode D1 and the negative terminal PV- of the PV DC power supply constitute the two output terminals (positive output terminal and negative output terminal) of the PV charging module 1; that is, the cathode of the first diode D1 is the positive output terminal of the PV charging module 1, and the negative terminal PV- of the PV DC power supply is the negative output terminal of the PV charging module 1. The sixth capacitor C6 is used for energy storage and filtering.

[0028] The fifth switch Q5 can be a transistor, MOSFET or IGBT.

[0029] In other embodiments, the PV charging module 1 is a buck module or a buck-boost module, etc., and the buck module, buck module or buck-boost module are collectively referred to as DC-DC converter modules.

[0030] In one embodiment, the inverter main power module 2 is a full-bridge inverter module, including a first capacitor C1, a first bridge arm, a second bridge arm, a second inductor L2, a third inductor L3, and a second capacitor C2. The positive terminal of the first capacitor C1 is connected to the positive output terminal of the PV charging module 1, and the positive terminal of the first capacitor C1 is connected to the negative output terminal (PV-) of the PV charging module 1. The first bridge arm includes a first switch Q1 and a second switch Q2. The current output terminal of the first switch Q1 is connected to the current input terminal of the second switch Q2 to form the first inverter terminal. The second bridge arm includes a third switch Q3 and a fourth switch Q4. The current output terminal of the third switch Q3 is connected to the current input terminal of the fourth switch Q4 to form the second inverter terminal. The current input terminals of the first switch Q1 and the third switch Q3 are connected to the positive terminal of the first capacitor C1, and the current output terminals of the second switch Q2 and the fourth switch Q4 are connected to the negative terminal of the first capacitor C1.

[0031] In this circuit, the first inverter terminal is connected to one end of the second inductor L2, the second inverter terminal is connected to one end of the third inductor L3, one end of the second capacitor C2 is connected to the other end of the second inductor L2, and the other end of the second capacitor C2 is connected to the other end of the third inductor L3. The second inductor L2, the second capacitor C2, and the third inductor L3 together form an LCL filter circuit to filter the voltages at the first and second inverter terminals, outputting an inverter voltage (AC voltage, i.e., the voltage across the second capacitor C2). This inverter voltage is the output voltage of the main power inverter module 2. The two ends of the second capacitor C2 form the two output terminals of the main power inverter module 2: the first output terminal and the second output terminal. The first output terminal is the inverter live wire L, and the second output terminal is the inverter neutral wire N. Furthermore, the main power inverter module 2 also has a third output terminal, which is the negative terminal of the first capacitor C1, i.e., the negative terminal PV- of the PV DC power supply.

[0032] In other embodiments, the second inductor L2 and the third inductor L3 can be combined into a single inductor, which is connected in series with the second capacitor C2 to form an LC filter circuit.

[0033] The first capacitor C1 is used for energy storage and filtering. The first and second bridge arms are the core power units for realizing the inverter function. They are symmetrical in structure and are both connected in parallel with the first capacitor C1. When the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are all MOSFETs, they can be referred to as the first MOSFET Q1, the second MOSFET Q2, the third MOSFET Q3, and the fourth MOSFET Q4. In this case, the first bridge arm is composed of the first MOSFET Q1 and the second MOSFET Q2 connected in series, and they are electrically connected through their drain and source (i.e., the source of the first MOSFET Q1 is connected to the drain of the second MOSFET Q2). The drain of the first MOSFET Q1 is connected to the positive terminal of the first capacitor C1, and the source of the second MOSFET Q2 is connected to the negative terminal of the first capacitor C1. The second bridge arm has the same structure as the first bridge arm, consisting of a third MOSFET Q3 and a fourth MOSFET Q4 connected in series (the source of the third MOSFET Q3 is connected to the drain of the fourth MOSFET Q4). The drain of the third MOSFET Q3 is also connected to the positive terminal of the first capacitor C1, and the source of the fourth MOSFET Q4 is connected to the negative terminal of the first capacitor C1. The four MOSFETs act as switching elements, and their on / off state is controlled by the PWM signal sent by the chip control module 6. The control method is conventional existing technology and will not be described in detail here.

[0034] Understandably, in addition to MOSFETs, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 can also be IGBTs, transistors, or combinations of two or more types. For example, in one embodiment, the first switch Q1 and the third switch Q3 are MOSFETs, and the second switch Q2 and the fourth switch Q4 are IGBTs; or, in another embodiment, the first switch Q1 and the third switch Q3 are IGBTs, and the second switch Q2 and the fourth switch Q4 are MOSFETs; or, in yet another embodiment, the first switch Q1 and the second switch Q2 are MOSFETs, and the third switch Q3 and the fourth switch Q4 are IGBTs; or, in yet another embodiment, the first switch Q1 and the second switch Q2 are IGBTs, and the third switch Q3 and the fourth switch Q4 are MOSFETs, and so on.

[0035] In actual operation, the first and second bridge arms work through complementary conduction logic to ultimately convert the DC voltage into the set AC voltage. The first capacitor C1 charges and discharges to supplement the current to ensure voltage continuity and reduce waveform distortion.

[0036] In other embodiments, the main inverter power module 2 can also be a half-bridge inverter module, an I-shaped inverter module, a T-shaped inverter module, etc., which will not be described in detail here.

[0037] Further, please see Figure 2The output module 4 includes a seventh capacitor C7, a fifth inductor L5, an eighth capacitor C8, and a first relay RY1. The two ends of the seventh capacitor C7 are the input terminals of the output module 4, which are connected to the two output terminals of the leakage current reduction circuit 3. More specifically, one end of the seventh capacitor C7 is the first input terminal of the output module 4, which is connected to the first output terminal of the leakage current reduction circuit 3 (i.e., the inverter live wire L), and the other end of the seventh capacitor C7 is the second input terminal of the output module 4, which is connected to the second output terminal of the leakage current reduction circuit 3 (i.e., the inverter neutral wire N).

[0038] The fifth inductor L5 is a common-mode inductor, comprising a first winding N1 and a second winding N2. The first winding N1 is connected in series with the inverter live wire L, and the second winding N2 is connected in series with the inverter neutral wire N. In one embodiment, the first end of the first winding N1 is connected to one end of the seventh capacitor C7, the second end of the first winding N1 is connected to one end of the eighth capacitor and one end of the first relay RY1, the other end of the first relay RY1 is connected to one end of the AC load Ro, the first end of the second winding N2 is connected to the other end of the seventh capacitor C7, and the second end of the second winding N2 is connected to the other end of the eighth capacitor and the other end of the AC load Ro.

[0039] Further, please see Figure 2 The mains power module 5 includes two relays: a second relay RY2 and a third relay RY3. One end of the second relay RY2 is the first input terminal of the mains power module 5, which is connected to the first output terminal of the leakage current reduction circuit 3. One end of the third relay RY3 is the second input terminal of the mains power module 5, which is connected to the second output terminal of the leakage current reduction circuit 3. The other end of the second relay RY2 is the first output terminal of the mains power module 5, and the other end of the third relay RY3 is the second output terminal of the mains power module 5. Specifically, one end of the second relay RY2 is connected to the inverter live wire L (i.e., the first output terminal of the leakage current reduction circuit 3), one end of the third relay RY3 is connected to the inverter neutral wire N (i.e., the second output terminal of the leakage current reduction circuit 3), the other end of the second relay RY2 is connected to the mains live wire I / P_L (also the first output terminal of the mains power module 5), and the other end of the third relay RY3 is connected to the mains neutral wire I / P_N (i.e., the second output terminal of the mains power module 5). By switching the two relays on and off, the mains power can be connected to or disconnected from the mains power module 5. Understandably, the on and off of the two relays can be controlled by the chip control module 6.

[0040] Please see Figure 3 This is another embodiment of a circuit for reducing leakage current in a photovoltaic energy storage system. (Compared to...) Figure 1 Compared to the embodiments shown, Figure 3The embodiment shown also includes an EMI suppression module 7, which is located between the inverter main power module 2 and the leakage current reduction circuit 3. The two input terminals of the EMI suppression module 7, namely the first input terminal and the second input terminal, are respectively connected to the first output terminal and the second output terminal of the inverter main power module 2. The two output terminals of the EMI suppression module 7, namely the first output terminal and the second output terminal, are connected to the first input terminal and the second input terminal of the leakage current reduction circuit 3. The EMI suppression module 7 is used to suppress EMI at the output terminal of the inverter main power module 2.

[0041] like Figure 4 As shown, with Figure 2 Compared to the embodiments shown, Figure 4 The illustrated embodiment also includes an EMI suppression module 7, which comprises a fourth inductor L4 and a third capacitor C3. The fourth inductor L4 is a common-mode inductor, comprising two windings N11 and N12. The first ends of the two windings are respectively connected to the two ends of the second capacitor C2 (i.e., the first end of winding N11 is connected to one end of the second capacitor C2, and the first end of winding N12 is connected to the other end of the second capacitor C2). The second ends of the two windings are respectively connected to the two ends of the third capacitor C3 (i.e., the second end of winding N11 is connected to one end of the third capacitor C3, and the second end of winding N12 is connected to the other end of the third capacitor C3). In this case, the two ends of the third capacitor C3 are the inverter live wire L and the inverter neutral wire N, respectively. It can be understood that the first ends of windings N11 and N12 are the first and second input terminals of the EMI suppression module 7, respectively; and the first and second output terminals of the third capacitor C3 are the first and second output terminals of the EMI suppression module 7, respectively.

[0042] Understandably, the AC load Ro can be powered by the inverter main power module 2 or by the mains power module 5.

[0043] The circuit of this utility model for reducing leakage current in photovoltaic energy storage system adopts a leakage current reduction circuit, which significantly reduces the common-mode voltage generated by the negative terminal of the photovoltaic panel to the N line of the power grid, and the corresponding leakage current of the inverter full bridge is reduced, thereby effectively reducing the leakage current in the photovoltaic energy storage system.

[0044] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A circuit for reducing leakage current in a photovoltaic energy storage system, comprising a PV charging module, an inverter main power module, an output module, and a mains power module, characterized in that, It also includes a leakage current reduction circuit; the input terminal of the inverter main power module is connected to the output terminal of the PV charging module, the input terminal of the leakage current reduction circuit is connected to the output terminal of the inverter main power module, the output terminal of the leakage current reduction circuit is connected to the input terminal of the output module and the input terminal of the mains power module, the mains power module is used to connect or disconnect the mains power, and the output module is used to output AC power to supply AC loads; The leakage current reduction circuit includes a fourth capacitor, a fifth capacitor, a first resistor, a second diode, and a third diode. One end of the fourth capacitor and the cathode of the second diode are connected to the first output terminal of the inverter main power module. The cathode of the third diode and one end of the fifth capacitor are connected to the second output terminal of the inverter main power module. The anode of the second diode and the anode of the third diode are connected to one end of the first resistor. The other end of the fourth capacitor, the other end of the fifth capacitor, and the other end of the first resistor are connected to the third output terminal of the inverter main power module, which is also the negative terminal of the PV DC power supply of the PV charging module. The first and second output terminals of the leakage current reduction circuit are the first and second output terminals of the inverter main power module, respectively.

2. The circuit for reducing leakage current in a photovoltaic energy storage system according to claim 1, characterized in that, The PV charging module is a boost module, a buck module, or a buck-boost module.

3. The circuit for reducing leakage current in a photovoltaic energy storage system according to claim 1, characterized in that, The main power inverter module includes a full-bridge inverter module, a half-bridge inverter module, an I-shaped inverter module, and a T-shaped inverter module.

4. The circuit for reducing leakage current in a photovoltaic energy storage system according to claim 1, characterized in that, It also includes a chip control module, the output of which is connected to the switch control terminals of the PV charging module, the inverter main power module, the output module, and the mains power module, respectively, and is used to send control signals to control the on / off state of the corresponding switches.

5. The circuit for reducing leakage current in a photovoltaic energy storage system according to claim 1, characterized in that, The switches in the PV charging module and the inverter main power module are transistors, MOSFETs, or IGBTs.

6. The circuit for reducing leakage current in a photovoltaic energy storage system according to claim 1, characterized in that, The switches in the output module and the mains power module are relays.

7. The circuit for reducing leakage current in a photovoltaic energy storage system according to claim 1, characterized in that, The mains power module includes two relays, namely a second relay and a third relay. One end of the second relay and one end of the third relay are respectively the first input terminal and the second input terminal of the mains power module, which are respectively connected to the first output terminal and the second output terminal of the leakage current reduction circuit. The other end of the second relay and one end of the third relay are respectively the first output terminal and the second output terminal of the mains power module, which are respectively connected to the mains live wire and the mains neutral wire.

8. The circuit for reducing leakage current in a photovoltaic energy storage system according to claim 1, characterized in that, The output module includes a seventh capacitor, a fifth inductor, an eighth capacitor, and a first relay. The two ends of the seventh capacitor are the input terminals of the output module, respectively connected to the first output terminal and the second output terminal of the leakage current reduction circuit. The fifth inductor is a common-mode inductor, including a first winding and a second winding. The first end of the first winding is connected to one end of the seventh capacitor, the second end of the first winding is connected to one end of the eighth capacitor and one end of the first relay, and the other end of the first relay is connected to one end of the AC load. The first end of the second winding is connected to the other end of the seventh capacitor, and the second end of the second winding is connected to the other end of the eighth capacitor and the other end of the AC load.

9. The circuit for reducing leakage current in a photovoltaic energy storage system according to claim 1, characterized in that, The second diode and the third diode are freewheeling diodes.

10. The circuit for reducing leakage current in a photovoltaic energy storage system according to claim 1, characterized in that, The first resistor is a cement resistor.

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