Discharge circuit and device for a photovoltaic inverter

Abstract

The application discloses a discharging circuit of a photovoltaic inverter, which comprises a signal detection end, a control chip, a voltage source end and a switch module. The signal detection end is used for receiving a trigger signal delivered by an external sampling circuit. The control chip is used for closing the output of a driving signal according to the trigger signal. The driving signal is used for driving the inverter bridge to work. The voltage source end is used for providing working voltage for the whole discharging circuit. The switch module is used for outputting a control voltage according to the trigger signal and the working voltage to make the direct-current bus capacitor and the ground wire conductive, so as to form a discharging loop. The design can reduce the discharging time and improve the integration of components.

Description

Technical Field

[0001] This application relates to the technical field of photovoltaic inverters, and more particularly to a discharge circuit and device for a photovoltaic inverter. Background Technology

[0002] A photovoltaic (PV) inverter is the core device in a PV power generation system that converts the direct current (DC) energy generated by solar panels into alternating current (AC) energy compatible with the power grid. Its performance directly affects the power generation efficiency and operational safety of the PV system. Inside the PV inverter, the DC bus, as a key power transmission channel connecting the front-end DC boost circuit and the back-end inverter bridge, is typically connected in parallel with a large-capacity DC bus capacitor. This capacitor is used to stabilize the bus voltage, suppress voltage fluctuations, and filter high-frequency ripple current, ensuring stable operation of the PV inverter under different operating conditions.

[0003] After a shutdown or abnormal turn-off, existing photovoltaic inverters often retain a high voltage on their DC bus capacitors. This can affect the inverter's restart and overall operational stability, and also pose a risk of electric shock to operators during maintenance or repair. Traditional bus discharge methods typically use relays to switch high-power discharge resistors, but due to limitations in response mechanisms and component characteristics, they often suffer from long response delays (approximately 10-30 seconds) and incomplete discharge processes, failing to reduce the bus voltage to a safe range in a short time. Furthermore, due to their compact structure and limited internal space, photovoltaic inverters struggle to integrate large high-power discharge resistors or power MOSFETs with sufficiently high rated voltage and current, significantly limiting rapid discharge and component integration. Utility Model Content

[0004] To address the technical deficiencies mentioned in the background section, this application provides a discharge circuit and device for a photovoltaic inverter, which can effectively reduce discharge time and improve the integration of components.

[0005] The present invention adopts the following technical solution: In a first aspect, a discharge circuit for a photovoltaic inverter is characterized by comprising: The signal detection terminal is electrically connected to an external sampling circuit, and the signal detection terminal is used to receive the trigger signal sent by the external sampling circuit; A control chip is electrically connected to the signal detection terminal. The control chip is used to turn off the output of the drive signal according to the trigger signal; wherein, the drive signal is used to drive the inverter bridge to work. The voltage source terminal is electrically connected to an external voltage source, and the voltage source terminal is used to provide the operating voltage for the entire discharge circuit; The switching module has one end electrically connected to the signal detection terminal and the voltage source terminal respectively, and the other end electrically connected between the DC bus capacitor and the ground wire. The switching module is used to output a control voltage to make the DC bus capacitor and the ground wire conduct according to the trigger signal and the working voltage, so as to form a discharge circuit.

[0006] Optionally, the switching module includes: The first switching unit has its input side electrically connected to the signal detection terminal and the voltage source terminal, and its output side electrically connected between the DC bus capacitor and the ground wire. The first switching unit is used to turn on according to the trigger signal and the working voltage to output a control voltage. The second switching unit has its control terminal electrically connected to the output side of the first switching unit, its input terminal for electrically connecting the bus capacitor, and its output terminal for grounding. The second switching unit is used to turn on the input terminal and the output terminal according to the control voltage, so that the DC bus capacitor is grounded through the second switching unit to complete the discharge.

[0007] Optionally, the first switching unit includes an optocoupler, the input side of which is electrically connected to the signal detection terminal and the voltage source terminal, and the output side of which is electrically connected to the second switching unit. The optocoupler is used to turn on according to the trigger signal and the operating voltage and output a control voltage.

[0008] Optionally, the second switching unit includes a MOS transistor, the gate of which is electrically connected to the output side of the optocoupler, the drain of which is electrically connected to the capacitor of the DC bus, and the source of which is grounded.

[0009] Optionally, it also includes a trigger signal shaping module, the trigger signal shaping module comprising: The signal shaping unit is electrically connected to an external sampling circuit. The signal shaping unit is used to invert and shape the low-level trigger signal sent by the external sampling circuit in order to send the shaped high-level trigger signal. A pull-down unit is provided, with one end electrically connected to the output of the signal shaping unit and the other end grounded. The pull-down unit is used to pull down and shape the trigger signal output by the signal shaping unit to prevent it from being left floating and causing false triggering of the control chip.

[0010] Optionally, the signal shaping unit includes two Schmitt triggers connected in parallel: a first Schmitt trigger and a second Schmitt trigger. The input terminals of both the first and second Schmitt triggers are electrically connected to the external sampling circuit, and the output terminals of both the first and second Schmitt triggers are electrically connected to the control chip and the input side of the optocoupler. The first and second Schmitt triggers are used to invert the received low-level trigger signal into a high-level trigger signal to cooperate with the operating voltage to turn on the optocoupler.

[0011] Optionally, the pull-down unit includes a first resistor, a second resistor, a third resistor, and a fourth resistor. The first resistor and the second resistor are connected in series. The first terminal of the first resistor is electrically connected to the first Schmitt trigger. The second terminal of the first resistor is electrically connected to the first terminal of the second resistor. The second terminal of the second resistor is grounded. The third resistor and the fourth resistor are connected in series. The first terminal of the third resistor is electrically connected to the output terminal of the second Schmitt trigger. The second terminal of the third resistor is electrically connected to the first terminal of the fourth resistor. The second terminal of the fourth resistor is grounded.

[0012] Optionally, it also includes a diode, a fifth resistor, and a sixth resistor. The anode of the diode is electrically connected to the output terminal of the first Schmitt trigger, the cathode of the diode is electrically connected to the input side of the optocoupler, the first terminal of the fifth resistor is electrically connected to the voltage source terminal, the second terminal of the fifth resistor is electrically connected to the input side of the optocoupler, the first terminal of the sixth resistor is electrically connected to the DC bus capacitor, and the second terminal of the sixth resistor is electrically connected to the drain of the MOS transistor.

[0013] Optionally, the MOS transistor is a high breakdown voltage gallium nitride MOS transistor.

[0014] Secondly, a discharge device for a photovoltaic inverter includes the discharge circuit of the photovoltaic inverter as described above; The circuit board on which the discharge circuit of the photovoltaic inverter is etched is located.

[0015] In summary, the beneficial effects of this utility model are as follows: By setting the signal detection terminal to be electrically connected to the external sampling circuit, the trigger signal sent by the external sampling circuit can be received. At the same time, the control chip is electrically connected to the signal detection terminal, and the output of the drive signal of the inverter bridge circuit can be stopped by receiving the trigger signal, thereby stopping the photovoltaic inverter from working. Then, the working voltage is provided to the entire discharge circuit through the external voltage source terminal, and the switching module receives the trigger signal and the working voltage, which can control the conduction between the DC bus capacitor and the ground wire, thereby achieving rapid discharge and complete discharge. Meanwhile, by setting the switching module as an optocoupler and a high breakdown voltage gallium nitride MOSFET, fast conduction can be achieved. At the same time, due to its small size, the space occupied on the PCB board can be reduced, and the integration of the PCB board can be improved. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the architecture of an embodiment of the present utility model; Figure 2 This is a circuit diagram of an embodiment of the present invention. Attached image description: 100. Signal detection terminal; 200. Control chip; 300, Voltage source terminal; 400. Switch module; 410. First switch unit; 420. Second switch unit; 500. Trigger signal shaping module; 510. Signal shaping unit; 520. Pull-down unit; U1, optocoupler; Q1, MOSFET; U2, first Schmitt trigger; U3, second Schmitt trigger; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; D1, diode; R5, fifth resistor; R6, sixth resistor. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] like Figure 1As shown, this application provides a discharge circuit for a photovoltaic inverter, including a signal detection terminal 100, a control chip 200, a voltage source terminal 300, and a switching module 400. The signal detection terminal 100 is electrically connected to an external sampling circuit and is used to receive a trigger signal from the external sampling circuit. The control chip 200 is electrically connected to the signal detection terminal 100 and is used to turn off the output of a drive signal according to the trigger signal. The drive signal is used to drive the inverter bridge to work. The voltage source terminal 300 is electrically connected to an external voltage source and is used to provide the operating voltage for the entire discharge circuit. One end of the switching module 400 is electrically connected to both the signal detection terminal 100 and the voltage source terminal 300, and the other end is electrically connected between the DC bus capacitor and the ground wire. The switching module 400 is used to output a control voltage according to the trigger signal and the operating voltage to make the DC bus capacitor and the ground wire conduct, forming a discharge loop.

[0021] In this embodiment, the sampling circuit is a part of the photovoltaic inverter circuit. The photovoltaic inverter circuit may include an interleaved flyback circuit, a DC circuit, an inverter bridge circuit, etc. The interleaved flyback circuit provides a DC source to the DC circuit, and the inverter bridge circuit converts the DC power into AC power, which can then be transmitted to the external AC voltage grid. The sampling circuit is used to collect data based on changes in current and voltage. When the sampling circuit detects that the voltage of the DC bus exceeds a set threshold, the sampling circuit generates a trigger signal, which is input through the signal detection terminal 100 and sent to the control chip 200. At this time, the control chip 200 stops outputting drive signals to the inverter bridge circuit, and the inverter bridge circuit stops working. Furthermore, by applying a working voltage and a trigger signal to the switch module 400, the switch module 400 will be turned on, thus forming a circuit between the DC bus capacitor and the ground wire, thereby releasing the voltage in the DC bus capacitor. By setting the switch module 400, the voltage in the DC bus capacitor can be released quickly, thereby greatly reducing the voltage release delay. At the same time, by grounding, the charge in the DC bus capacitor can be completely released.

[0022] like Figure 2As shown, the switch module 400 includes a first switch unit 410 and a second switch unit 420. The first switch unit 410 has its input side electrically connected to the signal detection terminal 100 and the voltage source terminal 300, and its output side electrically connected between the DC bus capacitor and the ground wire. The first switch unit 410 is used to conduct according to the trigger signal and the working voltage to output a control voltage. The second switch unit 420 has its control terminal electrically connected to the output side of the first switch unit 410, its input terminal used to electrically connect to the bus capacitor, and its output terminal used to ground. The second switch unit 420 is used to conduct the input terminal and the output terminal according to the control voltage, so that the DC bus capacitor is grounded through the second switch unit 420 to complete the discharge.

[0023] In this embodiment, the input side of the first switching unit 410 is connected to the signal detection terminal 100 to receive a trigger signal. Simultaneously, it receives the operating voltage through the voltage source terminal 300, and thus outputs a control voltage through the output side of the first switching unit 410. Since the output side of the first switching unit 410 is electrically connected to the control terminal of the second switching unit 420, when the control terminal of the second switching unit 420 receives the control voltage, the second switching unit 420 will also conduct. Because the second switching unit 420 is electrically connected between the DC bus capacitor and the ground wire, when the second switching unit 420 is turned on, the DC bus capacitor and the ground wire will conduct, thereby releasing the voltage in the DC bus capacitor. Furthermore, since there are no other components between the DC bus capacitor and the ground wire, only a switching unit and the sixth resistor R6, it can quickly conduct upon receiving the trigger signal, allowing the voltage in the DC bus capacitor to be released more rapidly.

[0024] like Figure 2 As shown, the first switching unit 410 includes an optocoupler U1. The input side of the optocoupler U1 is electrically connected to the signal detection terminal 100 and the voltage source terminal 300. The output side of the optocoupler U1 is electrically connected to the second switching unit 420. The optocoupler U1 is used to turn on according to the trigger signal and the working voltage and output a control voltage.

[0025] In this embodiment, the first switching unit 410 can be an optocoupler U1. The optocoupler U1 receives a trigger signal and operating voltage at its input side, enabling it to conduct. Simultaneously, it outputs a control voltage at its output side, providing the conditions for the second switching unit 420 to conduct. Furthermore, because the optocoupler U1 is relatively small, it can be arranged on a space-efficient PCB board, improving the integration and reducing the overall size of this embodiment.

[0026] like Figure 2As shown, the second switching unit 420 includes a MOS transistor Q1. The gate of the MOS transistor Q1 is electrically connected to the output side of the optocoupler U1, the drain of the MOS transistor Q1 is electrically connected to the capacitor of the DC bus, and the source of the MOS transistor Q1 is grounded.

[0027] In this embodiment, the second switching unit 420 may include a MOSFET Q1, specifically a high breakdown voltage gallium nitride MOSFET Q1. The high breakdown voltage gallium nitride MOSFET Q1 features high voltage resistance, fast turn-on speed, low on-resistance, small size, and excellent heat dissipation. By setting the second switching unit 420 as a high breakdown voltage gallium nitride MOSFET Q1, the voltage in the DC bus capacitor can be quickly released. Furthermore, due to its small size, more other components can be placed on the PCB, avoiding the need for traditional relay switching of high-power discharge resistors, which requires approximately 10-30 seconds, thus improving component integration. Specifically, the gate of the MOSFET Q1 receives the control voltage from the optocoupler U1. This control voltage enables conduction between its drain and source, with the drain electrically connected to the DC bus capacitor and the source grounded. This allows the DC bus capacitor to conduct to ground, forming a discharge circuit and rapidly releasing the voltage in the DC bus capacitor, with a release time ≤20ms.

[0028] like Figure 2 As shown, this embodiment of the application includes a trigger signal shaping module 500, which includes a signal shaping unit 510 and a pull-down unit 520. The signal shaping unit 510 is electrically connected to an external sampling circuit. The signal shaping unit 510 is used to invert and shape the low-level trigger signal sent by the external sampling circuit to send a shaped high-level trigger signal. One end of the pull-down unit 520 is electrically connected to the output terminal of the signal shaping unit 510, and the other end of the pull-down unit 520 is grounded. The pull-down unit 520 is used to pull down and shape the trigger signal output by the signal shaping unit 510 to prevent it from being floating and causing false triggering of the control chip 200.

[0029] In this embodiment, since the sampling circuit will pull the trigger signal low after detecting overcurrent or overvoltage, forming a low level, the signal shaping unit 510 is set to invert the pulled-down trigger signal and shape it to transmit a high-level trigger signal. Then, by setting the pull-down unit 520 to pull down and shape the high-level trigger signal transmitted by the signal shaping unit 510, it is possible to prevent the control chip 200 from being falsely triggered due to floating, thereby improving the stability of this embodiment.

[0030] like Figure 2As shown, the signal shaping unit 500 includes two Schmitt triggers U2 and U3 connected in parallel. The input terminals of the first Schmitt trigger U2 and the second Schmitt trigger U3 are both electrically connected to the external sampling circuit. The output terminals of the first Schmitt trigger U2 and the second Schmitt trigger U3 are both electrically connected to the input side of the control chip 200 and the optocoupler U1. The first Schmitt trigger U2 and the second Schmitt trigger U3 are used to invert the received low-level trigger signal into a high-level trigger signal to cooperate with the operating voltage to turn on the optocoupler U1.

[0031] In this embodiment of the application, by setting two Schmitt triggers U2 and U3 connected in parallel, the input terminals of the two Schmitt triggers are connected to an external sampling circuit, and the output terminals are electrically connected to the optocoupler U1 and the control chip 200. By setting two Schmitt triggers, the input trigger signal can be shaped and inverted.

[0032] like Figure 2 As shown, the pull-down unit 520 includes a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The first resistor R1 and the second resistor R2 are connected in series. The first end of the first resistor R1 is electrically connected to the first Schmitt trigger U2, and the second end of the first resistor R1 is electrically connected to the first end of the second resistor R2. The second end of the second resistor R2 is grounded. The third resistor R3 and the fourth resistor R4 are connected in series. The first end of the third resistor R3 is electrically connected to the output terminal of the second Schmitt trigger U3, and the second end of the third resistor R3 is electrically connected to the first end of the fourth resistor R4. The second end of the fourth resistor R4 is grounded.

[0033] By setting the first resistor R1 and the second resistor R2 in series, and the third resistor R3 and the fourth resistor R4 in series, it is possible to prevent the control chip 200 from being falsely triggered due to the output terminal of the Schmitt trigger being left floating, and to prevent the high-level trigger signal after inversion from flowing out through the ground wire.

[0034] like Figure 2 As shown, this embodiment of the application also includes a diode D1, a fifth resistor R5, and a sixth resistor R6. The anode of the diode D1 is electrically connected to the output terminal of the first Schmitt trigger U2, and the cathode of the diode D1 is electrically connected to the input side of the optocoupler U1. The first terminal of the fifth resistor R5 is electrically connected to the voltage source terminal 300, and the second terminal of the fifth resistor R5 is electrically connected to the input side of the optocoupler U1. The first terminal of the sixth resistor R6 is electrically connected to the DC bus capacitor, and the second terminal of the sixth resistor R6 is electrically connected to the drain of the MOS transistor Q1.

[0035] In this embodiment, by setting diode D1, reverse signal interference can be prevented and the port of control chip 200 can be protected. By setting fifth resistor R5, current can be limited for optocoupler U1 to prevent excessive current from burning out optocoupler U1. By setting sixth resistor R6, excessive current in DC bus capacitor can be prevented from burning out MOSFET Q1.

[0036] The second aspect of this application discloses a discharge device for a photovoltaic inverter, which includes a discharge circuit and a circuit board for the photovoltaic inverter as described above. The discharge circuit of the photovoltaic inverter is etched on the circuit board (not shown in the figure). By setting up this discharge device, the DC bus capacitor in the photovoltaic inverter can be discharged, avoiding dangerous situations caused by the untimely discharge response of traditional methods. At the same time, since the device has fewer and smaller components, it can improve the component integration on the PCB board of the photovoltaic inverter.

[0037] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they 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. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0038] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A discharge circuit for a photovoltaic inverter, characterized in that, include: The signal detection terminal (100) is electrically connected to an external sampling circuit, and the signal detection terminal (100) is used to receive the trigger signal sent by the external sampling circuit; A control chip (200) is electrically connected to the signal detection terminal (100). The control chip (200) is used to turn off the output of the drive signal according to the trigger signal; wherein the drive signal is used to drive the inverter bridge to work. The voltage source terminal (300) is electrically connected to an external voltage source, and the voltage source terminal (300) is used to provide the operating voltage for the entire discharge circuit; The switch module (400) has one end electrically connected to the signal detection terminal (100) and the voltage source terminal (300) respectively, and the other end electrically connected between the DC bus capacitor and the ground wire. The switch module (400) is used to output a control voltage to make the DC bus capacitor and the ground wire conduct according to the trigger signal and the working voltage, so as to form a discharge circuit.

2. The discharge circuit of the photovoltaic inverter as described in claim 1, characterized in that, The switching module (400) includes: The first switching unit (410) has its input side electrically connected to the signal detection terminal (100) and the voltage source terminal (300), and its output side electrically connected between the DC bus capacitor and the ground wire. The first switching unit (410) is used to turn on according to the trigger signal and the working voltage to output the control voltage. The second switching unit (420) has its control terminal electrically connected to the output side of the first switching unit (410), its input terminal for electrically connecting the bus capacitor, and its output terminal for grounding. The second switching unit (420) is used to turn on the input terminal and the output terminal according to the control voltage, so that the DC bus capacitor is grounded through the second switching unit (420) to complete the discharge.

3. The discharge circuit of the photovoltaic inverter as described in claim 2, characterized in that, The first switching unit (410) includes an optocoupler (U1). The input side of the optocoupler (U1) is electrically connected to the signal detection terminal (100) and the voltage source terminal (300). The output side of the optocoupler (U1) is electrically connected to the second switching unit (420). The optocoupler (U1) is used to turn on according to the trigger signal and the working voltage and output a control voltage.

4. The discharge circuit of the photovoltaic inverter as described in claim 3, characterized in that, The second switching unit (420) includes a MOS transistor (Q1), the gate of which is electrically connected to the output side of the optocoupler (U1), the drain of which is electrically connected to the capacitor of the DC bus, and the source of which is grounded.

5. The discharge circuit of the photovoltaic inverter as described in claim 4, characterized in that, It also includes a trigger signal shaping module (500), which includes: The signal shaping unit (510) is electrically connected to an external sampling circuit. The signal shaping unit (510) is used to invert and shape the low-level trigger signal sent by the external sampling circuit so as to send the shaped high-level trigger signal. A pull-down unit (520) is provided, one end of which is electrically connected to the output of the signal shaping unit (510), and the other end of which is grounded. The pull-down unit (520) is used to pull down and shape the trigger signal output by the signal shaping unit (510) to prevent it from being left floating and causing false triggering of the control chip (200).

6. The discharge circuit of the photovoltaic inverter as described in claim 5, characterized in that, The signal shaping unit (510) includes two parallel Schmitt triggers (U2) and a second Schmitt trigger (U3). The input terminals of the first Schmitt trigger (U2) and the second Schmitt trigger (U3) are electrically connected to the external sampling circuit. The output terminals of the first Schmitt trigger (U2) and the second Schmitt trigger (U3) are electrically connected to the input side of the control chip (200) and the optocoupler (U1). The first Schmitt trigger (U2) and the second Schmitt trigger (U3) are used to invert the received low-level trigger signal into a high-level trigger signal to cooperate with the operating voltage to turn on the optocoupler (U1).

7. The discharge circuit of the photovoltaic inverter as described in claim 6, characterized in that, The pull-down unit (520) includes a first resistor (R1), a second resistor (R2), a third resistor (R3), and a fourth resistor (R4). The first resistor (R1) and the second resistor (R2) are connected in series. The first terminal of the first resistor (R1) is electrically connected to the first Schmitt trigger (U2). The second terminal of the first resistor (R1) is electrically connected to the first terminal of the second resistor (R2). The second terminal of the second resistor (R2) is grounded. The third resistor (R3) and the fourth resistor (R4) are connected in series. The first terminal of the third resistor (R3) is electrically connected to the output terminal of the second Schmitt trigger (U3). The second terminal of the third resistor (R3) is electrically connected to the first terminal of the fourth resistor (R4). The second terminal of the fourth resistor (R4) is grounded.

8. The discharge circuit of the photovoltaic inverter as described in claim 6, characterized in that, It also includes a diode (D1), a fifth resistor (R5), and a sixth resistor (R6). The anode of the diode (D1) is electrically connected to the output terminal of the first Schmitt trigger (U2), and the cathode of the diode (D1) is electrically connected to the input side of the optocoupler (U1). The first terminal of the fifth resistor (R5) is electrically connected to the voltage source terminal (300), and the second terminal of the fifth resistor (R5) is electrically connected to the input side of the optocoupler (U1). The first terminal of the sixth resistor (R6) is electrically connected to the DC bus capacitor, and the second terminal of the sixth resistor (R6) is electrically connected to the drain of the MOS transistor (Q1).

9. The discharge circuit of the photovoltaic inverter as described in claim 4, characterized in that, The MOS transistor (Q1) is a high breakdown voltage gallium nitride MOS transistor.

10. A discharge device for a photovoltaic inverter, characterized in that, Includes the discharge circuit of the photovoltaic inverter as described in any one of claims 1-9; The circuit board on which the discharge circuit of the photovoltaic inverter is etched is located.

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