Photovoltaic energy storage power conversion system and fault isolation method

Abstract

The embodiment of the invention provides a photovoltaic energy storage power conversion system and a fault isolation method wherein the photovoltaic energy storage power conversion system comprises: a plurality of photovoltaic input units, each photovoltaic input unit comprising a photovoltaic input port, a turn-off switch module and a step-down circuit, the positive electrode of the photovoltaic input port is connected to the input end of the step-down circuit through the turn-off switch module; the positive electrode of the battery is connected with the output end of the step-down circuit, and the negative electrode of the battery is connected with the negative electrode of the photovoltaic input port; the direct current input end of the conversion unit is connected with the battery, and the alternating current output end of the conversion unit is used for being connected with an alternating current power grid or a load. Through the scheme of the invention, under the condition of multi-path photovoltaic input, the reliability of the system is improved, and the mutual influence among different paths of photovoltaic ports is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, in particular to a photovoltaic energy storage power conversion system and a fault isolation method. BACKGROUND

[0002] At present, a photovoltaic energy storage bidirectional power conversion system (PCS) is widely applied in the field of new energy. The photovoltaic energy storage inverter generally has two or more than two photovoltaic (PV) inputs. When a problem occurs in one of the PV input ports of the photovoltaic energy storage inverter, the PV port with the problem cannot be isolated, so that the remaining PV inputs can continue to generate electricity. The reliability of the photovoltaic energy storage power conversion system is insufficient. SUMMARY

[0003] The purpose of the embodiment of the present application is to provide a photovoltaic energy storage power conversion system and a fault isolation method, which can solve the problem that when a problem occurs in one of the PV input ports of the photovoltaic energy storage inverter, the PV port with the problem cannot be isolated, so that the remaining PV inputs can continue to generate electricity. The reliability of the photovoltaic energy storage power conversion system is insufficient.

[0004] Therefore, the embodiment of the first aspect of the present application provides a photovoltaic energy storage power conversion system.

[0005] The embodiment of the second aspect of the present application provides a fault isolation method.

[0006] In order to achieve the above-mentioned purpose, the embodiment of the first aspect of the present application provides a photovoltaic energy storage power conversion system, which comprises: a plurality of photovoltaic input units, the photovoltaic input unit comprising a photovoltaic input port, a shutdown switch module and a step-down circuit, the positive electrode of the photovoltaic input port being connected to the input end of the step-down circuit through the shutdown switch module; a battery, the positive electrode of the battery being connected to the output end of the step-down circuit, and the negative electrode of the battery being connected to the negative electrode of the photovoltaic input port; a conversion unit, the direct current input end of the conversion unit being connected to the battery, and the alternating current output end of the conversion unit being used for connecting an alternating current power grid or a load; wherein the shutdown switch module is configured to: when it is detected that the voltage of the step-down circuit exceeds a first preset voltage threshold, it is determined that a short circuit fault occurs in the step-down circuit, and the shutdown switch module is turned off; or when it is detected that the voltage of the photovoltaic input port is lower than a second preset voltage threshold, and there is a current flowing from the battery bus to the photovoltaic input port, it is determined that the photovoltaic input port is externally short-circuited, and the shutdown switch module is turned off.

[0007] The photovoltaic energy storage power conversion system with the multi-path photovoltaic port fault isolation function provided by the application has the core that the shutdown switch module integrated in each photovoltaic input unit and the intelligent detection control logic cooperate with each other: when the voltage of the voltage reduction circuit exceeds the first preset voltage threshold, it is determined that the voltage reduction circuit has a short circuit fault, and the shutdown switch module is turned off; or when the voltage of the photovoltaic input port is lower than the second preset voltage threshold, and there is current flowing from the battery bus to the photovoltaic input port, it is determined that the photovoltaic input port has an external short circuit, and the shutdown switch module is turned off, so that the two key faults of the internal short circuit of the voltage reduction circuit and the external short circuit of the photovoltaic input port are accurately and quickly diagnosed and isolated, thereby ensuring that the fault path can be quickly cut off when a single photovoltaic input unit fails, and the remaining part of the photovoltaic energy storage power conversion system can continue to operate stably.

[0008] In some technical solutions, the shutdown switch module comprises a first field effect tube and a second field effect tube; the source of the first field effect tube and the source of the second field effect tube are connected; the drain of the first field effect tube is connected to the positive pole of the photovoltaic input port; and the drain of the second field effect tube is connected to the input of the voltage reduction circuit.

[0009] In the present solution, the shutdown switch module protects the specific circuit structure composed of the first field effect tube and the second field effect tube connected in a common source manner back-to-back, and the source of the first field effect tube and the source of the second field effect tube are connected, which utilizes the characteristics of the reverse series connection of the internal body diodes of the two field effect tubes, realizes the bidirectional controllable conduction and shutdown of the current, thereby providing a hardware basis for fault isolation that can effectively block the forward fault current and the reverse discharge current at the same time, and ensuring the reliability of the fault isolation operation.

[0010] In some technical solutions, the shutdown switch module further comprises a first driving assembly, the control signal output end of the first driving assembly is connected to the drain of the first field effect tube, and the control signal output end of the first driving assembly is connected to the drain of the second field effect tube, and the first driving assembly is used for shutting off or closing the shutdown switch module.

[0011] In the present solution, the control signal output end of the first driving assembly is connected to the gate of the first field effect tube and the gate of the second field effect tube, respectively, so as to realize the accurate control of the driving signal on the switch state of the shutdown switch module, and ensure that the fault isolation instruction can be quickly executed by the first field effect tube and the second field effect tube.

[0012] In some technical solutions, the photovoltaic energy storage power conversion system further comprises a photovoltaic assembly connected to the photovoltaic input port.

[0013] In this scheme, the energy source of the photovoltaic energy storage power conversion system is further defined, and the connection between the external energy source and the internal conversion equipment is formed by connecting photovoltaic modules and photovoltaic input ports.

[0014] In some technical solutions, the photovoltaic energy storage power conversion system may optionally include a battery management component, which is connected to the battery and used to manage the battery's state parameters.

[0015] In this solution, the battery management component connects to the battery to intelligently sense, monitor, and manage the battery's status parameters. This enhances the reliability of fault diagnosis through accurate feedback of battery data and constructs a safety protection barrier for the battery itself, thereby improving the overall safety of the photovoltaic energy storage power conversion system.

[0016] In some technical solutions, optionally, the step-down circuit includes: a first switching transistor, the drain of which is connected to a turn-off switch module; a second switching transistor, the drain of which is connected to the source of the first switching transistor, the source of which is connected to the negative terminal of the photovoltaic input port; and an inductor, the first end of which is connected to the switching node between the source of the first switching transistor and the drain of the second switching transistor, and the second end of which is connected to the positive terminal of the battery.

[0017] In this scheme, the step-down circuit includes a first switching transistor, a second switching transistor, and an inductor. The source of the first switching transistor and the drain of the second switching transistor are connected, and the inductor is connected to the switching node between the first and second switching transistors, providing a high-efficiency and reliable step-down rectification function for the photovoltaic energy storage power conversion system.

[0018] In some technical solutions, the step-down circuit may optionally include a capacitor, with the first end of the capacitor connected to the drain of the first switching transistor and the second end of the capacitor connected to the source of the second switching transistor.

[0019] In this scheme, a capacitor is connected in parallel between the drain of the first switching transistor and the source of the second switching transistor in the step-down circuit. The capacitor provides a stable operating voltage for the core switching circuit and effectively suppresses electromagnetic interference by providing local energy buffer and high-frequency noise bypass path, thereby significantly improving the stability, reliability and electromagnetic compatibility of the entire power conversion stage.

[0020] In some technical solutions, the step-down circuit may optionally include: a second driving component, wherein the control signal output terminal of the second driving component is connected to the gate of the first switching transistor, the control signal output terminal of the second driving component is connected to the gate of the second switching transistor, and the second driving component is used to control the first switching transistor and the second switching transistor to conduct alternately.

[0021] In this solution, the buck circuit also includes a second driver component dedicated to the power switching transistors. By connecting the control signal output of the second driver component to the gate of the first switching transistor, the buck circuit structure is elevated to a controllable and precisely executable power conversion unit. As a key hub connecting the system control logic and the power switching operation, the second driver component ensures efficient alternating conduction of the first and second switching transistors by providing high-speed, reliable gate drive signals and integrating hardware protection functions.

[0022] In some technical solutions, the conversion unit optionally includes: a resonant converter, the input terminal of which is connected to a battery; and an inverter (INV), the DC input terminal of which is connected to the output terminal of the resonant converter, the AC output terminal of which is connected to an AC port, and connected to an AC power grid or load through the AC port.

[0023] In this scheme, the conversion unit is a two-stage architecture consisting of a resonant converter and an inverter. The resonant converter is responsible for achieving electrical isolation and efficient DC-DC conversion at the battery input, while the inverter is responsible for generating grid-connected or off-grid AC power in a coordinated manner.

[0024] An embodiment of the second aspect of the present invention provides a fault isolation method for the photovoltaic energy storage power conversion system of the first aspect. The photovoltaic energy storage power conversion system includes multiple photovoltaic input units, a battery, and a conversion unit. The photovoltaic input unit includes a photovoltaic input port, a shutdown switch module, and a step-down circuit. The fault isolation method includes: acquiring a first state parameter of the step-down circuit and a second state parameter of the photovoltaic input port in the multiple photovoltaic input units; acquiring the voltage parameter of the battery; identifying at least one faulty photovoltaic input unit based on the first state parameter, the second state parameter, and the voltage parameter; and controlling the shutdown switch module in the faulty photovoltaic input unit to turn off. When the shutdown switch module in at least one faulty photovoltaic input unit is turned off, and the faulty photovoltaic input unit and the battery are electrically isolated, the remaining at least one photovoltaic input unit continues to operate.

[0025] A fault isolation method for photovoltaic energy storage power conversion systems continuously acquires and comprehensively analyzes the circuit state parameters and battery voltage parameters of each photovoltaic input unit, intelligently diagnoses and accurately locates the specific photovoltaic input unit that has failed, and then selectively shuts down the shutdown switch module in the faulty unit to electrically isolate it from the system bus, while ensuring that the remaining normal photovoltaic input units continue to work. This achieves a fundamental transformation of the system from shutdown upon failure to derating operation during failure, significantly improving the availability and reliability of the system.

[0026] Additional aspects and advantages of the technical solutions of the present invention will become apparent in the following description or may be learned by practice of the invention. Attached Figure Description

[0027] Figure 1 A schematic diagram of the power topology architecture of a photovoltaic-storage inverter in related technologies is shown;

[0028] Figure 2 A schematic diagram of a power topology failure in a photovoltaic-storage inverter is shown in the relevant technology.

[0029] Figure 3 One of the circuit diagrams of a photovoltaic energy storage power conversion system according to this application is shown;

[0030] Figure 4 A circuit diagram of the off switch module according to this application is shown;

[0031] Figure 5 A second circuit diagram of a photovoltaic energy storage power conversion system according to this application is shown;

[0032] Figure 6 A third circuit diagram of a photovoltaic energy storage power conversion system according to this application is shown;

[0033] Figure 7 A circuit diagram of the step-down circuit according to this application is shown;

[0034] Figure 8 A circuit diagram of the conversion unit according to this application is shown;

[0035] Figure 9 A fourth circuit diagram of a photovoltaic energy storage power conversion system according to this application is shown;

[0036] Figure 10 A flowchart illustrating the fault isolation method according to this application is shown.

[0037] Wherein, 102': photovoltaic input terminal; 104': resonant converter; 106': inverter;

[0038] 100: Photovoltaic energy storage power conversion system; 102: Photovoltaic input unit; 1022: Photovoltaic input port; 1024: Shutdown switch module; 1026: Buck circuit; 104: Battery; 1042: Battery bus; 106: Conversion unit; MOS1: First field-effect transistor; MOS2: Second field-effect transistor; 10242: First drive component; 10244: Second drive component; 108: Photovoltaic module; C1: Capacitor; C2: Inductor; Q1: First switching transistor; Q2: Second switching transistor; 1062: Resonant converter; 1064: Inverter; 110: Battery management component; 300: Load. Detailed Implementation

[0039] To better understand the above-described objectives, features, and advantages of the embodiments of the present invention, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0040] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, embodiments of the invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0041] In the relevant technical solutions, the PV input voltage specifications for home photovoltaic-storage inverters are: 30V ~ 80V; maximum input current 14A; a total of 4 channels.

[0042] Battery voltage range: 22.4V ~ 28.8V.

[0043] Photovoltaic-storage inverter power topology architecture as follows Figure 1 As shown, the 4-channel photovoltaic input terminal 102' can independently function as a buck converter (BUCK) to step down the voltage to the battery voltage, and then output AC power through the resonant converter 104' (LLC Resonant Converter, LLC) and inverter 106'.

[0044] Problems with the solutions in related technologies, such as Figure 2 As shown, the direction of the dashed arrow indicates the direction of the fault current. When the upper metal-oxide-semiconductor field-effect transistor (MOSFET) of one of the PV BUCK circuits is short-circuited, the PV input voltage will be directly applied to the battery bus. After the PCS inverter detects the fault, it needs to shut down the Battery Management System (BMS), i.e., the battery management component, to cut off the current path between the BMS and the PV circuits. The other three normal PV circuits will still not work properly, and the entire PCS will be out of service and require maintenance.

[0045] As the market develops, people are increasingly concerned about the reliability of such inverters. They hope that if a problem occurs at one of the PV input ports of the PCS inverter, the photovoltaic-storage inverter can isolate the faulty PV port, while the remaining PV inputs can continue to generate electricity and maintain the normal operation of the machine.

[0046] The photovoltaic energy storage power conversion system and fault isolation method provided in this application will be described in detail below with reference to specific embodiments and application scenarios.

[0047] like Figure 3 As shown, this embodiment provides a photovoltaic energy storage power conversion system 100, including: multiple photovoltaic input units 102, each photovoltaic input unit 102 including a photovoltaic input port 1022, a shutdown switch module 1024, and a step-down circuit 1026, the positive terminal of the photovoltaic input port 1022 being connected to the input terminal of the step-down circuit 1026 through the shutdown switch module 1024; a battery 104, the positive terminal of the battery 104 being connected to the output terminal of the step-down circuit 1026, and the negative terminal of the battery 104 being connected to the negative terminal of the photovoltaic input port 1022; and a conversion unit 106, the DC input terminal of the conversion unit 106 and... The battery 104 is connected, and the AC output terminal of the conversion unit 106 is used to connect to the AC power grid or the load 300. The shutdown switch module 1024 is configured to: determine that a short circuit fault has occurred in the buck circuit 1026 when the voltage of the buck circuit 1026 exceeds a first preset voltage threshold, and shut down the shutdown switch module 1024; or determine that an external short circuit has occurred in the photovoltaic input port 1022 when the voltage of the photovoltaic input port 1022 is lower than a second preset voltage threshold and there is current flowing from the battery bus 1042 to the photovoltaic input port 1022, and shut down the shutdown switch module 1024.

[0048] The photovoltaic energy storage power conversion system 100 with multi-channel photovoltaic port fault isolation function provided by the present invention is based on the core of the turn-off switch module 1024 integrated in each photovoltaic input unit 102 and the intelligent detection and control logic that works in conjunction with it: when the voltage of the step-down circuit 1026 is detected to exceed the first preset voltage threshold, it is determined that the step-down circuit 1026 has a short circuit fault and the turn-off switch module 1024 is turned off; or when the voltage of the photovoltaic input port 1022 is detected to be lower than the second preset voltage threshold and there is current flowing from the battery bus 1042 to the photovoltaic input port 1022, it is determined that the photovoltaic input port 1022 is externally short-circuited and the turn-off switch module 1024 is turned off. This achieves accurate and rapid diagnosis and isolation of two key faults: internal short circuit of the step-down circuit 1026 and external short circuit of the photovoltaic input port 1022. This ensures that when a single photovoltaic input unit 102 fails, the fault path can be quickly cut off, ensuring the continuous and stable operation of the rest of the photovoltaic energy storage power conversion system 100.

[0049] Each photovoltaic input unit 102 is independent and includes a photovoltaic input port 1022, a shutdown switch module 1024, and a step-down circuit 1026. The photovoltaic input port 1022 is used to connect an external photovoltaic module 108, and the step-down circuit 1026 is used to stabilize the fluctuating photovoltaic voltage to the voltage required by the battery 104.

[0050] Battery 104 is directly connected to the output terminal of step-down circuit 1026. The negative terminal of battery 104 shares a common ground with the negative terminals of all photovoltaic input ports 1022, forming a complete circuit.

[0051] The DC input terminal of the conversion unit 106 is connected to the battery 104, obtains stable DC power from the battery 104, and then inverts it into AC power to supply the load 300 or send it back to the power grid.

[0052] It should be emphasized that in this application, the shutdown switch module 1024 is no longer a simple switch, but an intelligent unit that integrates a fault diagnosis algorithm. The shutdown switch module 1024 is configured to accurately identify circuit faults within the photovoltaic energy storage power conversion system 100.

[0053] Specifically, the photovoltaic energy storage power conversion system 100 continuously monitors the voltage of the step-down circuit 1026 itself, that is, the voltage after the switch module 1024 is turned off. When the switch inside the step-down circuit 1026 breaks down and short-circuits, the high-voltage photovoltaic input will be directly and unimpededly transmitted to the subsequent components through the short-circuited switch.

[0054] When the photovoltaic energy storage power conversion system 100 detects that the voltage of the step-down circuit 1026 exceeds the first preset voltage threshold, it determines that a short circuit fault has occurred inside the step-down circuit 1026.

[0055] For example, the first preset voltage threshold is set at a value higher than the maximum voltage value of the buck circuit 1026 during normal operation.

[0056] When a short circuit fault is detected inside the step-down circuit 1026, i.e., the voltage of the step-down circuit 1026 exceeds the first preset voltage threshold, the turn-off switch module 1024 is immediately turned off, thereby physically disconnecting the faulty step-down circuit 1026 from the photovoltaic input port 1022, preventing the short circuit fault from being transmitted between the multi-channel photovoltaic input unit 102 and the battery 104.

[0057] Furthermore, the voltage and current direction of the photovoltaic input port 1022 are monitored simultaneously. When a short circuit occurs in the photovoltaic panel line or connector corresponding to the photovoltaic input port 1022, the voltage of the photovoltaic input port 1022 is lower than the second preset voltage threshold.

[0058] More importantly, while the voltage at the photovoltaic input port 1022 is lower than the second preset voltage threshold, the voltage at the battery 104 will be higher than the voltage at the short-circuit point. This causes current to flow out from the positive terminal of the battery 104, flow in reverse through the buck circuit 1026, and then flow to the short-circuited photovoltaic input port 1022. The reverse current output from the battery 104 creates a dangerous reverse discharge, which not only wastes electrical energy but also poses a risk of burning out circuit components.

[0059] Therefore, when both conditions are met simultaneously, such as the voltage of the photovoltaic input port 1022 being lower than the second preset voltage threshold and the presence of current flowing from the battery bus 1042 to the photovoltaic input port 1022, it is determined that the photovoltaic input port 1022 is externally short-circuited, and the corresponding photovoltaic input unit 102 shuts off the shut-off switch module 1024, blocking the reverse discharge path of the battery 104 energy.

[0060] Understandably, compared to related technical solutions where a single point of failure causes the entire system to shut down, this solution enables derated operation during failures, meaning the photovoltaic energy storage power conversion system 100 continues to operate normally at partial power. This is crucial for applications requiring stability, significantly improving the operation and maintenance efficiency and reliability of the photovoltaic energy storage power conversion system 100 with multiple photovoltaic input ports 1022.

[0061] Specifically, regarding the internal short circuit fault of the step-down circuit 1026, a typical characteristic of this fault is that the high voltage on the photovoltaic side directly flows into the battery 104 in the subsequent circuit of the photovoltaic energy storage power conversion system 100. Therefore, the fault is determined by monitoring whether the voltage of the battery 104 bus abnormally rises to exceed a first preset voltage threshold. The first preset voltage threshold is a specific threshold set based on the system safety voltage. Once it is exceeded, it confirms that there is an internal short circuit in the step-down circuit 1026, rather than normal voltage fluctuations.

[0062] To address the external short circuit fault at the photovoltaic input port 1022, a typical characteristic of this fault is a sudden drop in photovoltaic port voltage. Simultaneously, because the voltage of battery 104 is higher than the short circuit point, current flows in reverse from battery 104 to the short circuit point. Therefore, the shutdown switch module 1024 is configured to employ dual criteria: first, it detects whether the voltage at the photovoltaic input port 1022 is lower than a second preset voltage threshold; second, it detects whether current flows from the battery bus 1042 to the corresponding photovoltaic input port 1022. Only when both conditions are met is an external short circuit at the photovoltaic input port 1022 determined, thus effectively preventing false alarms caused by voltage drops.

[0063] Once a short circuit is detected inside the buck circuit 1026 or outside the photovoltaic input port 1022, an isolation action is immediately performed, isolating the shutdown switch module 1024 in the corresponding photovoltaic input unit 102. This causes the shutdown switch module 1024 in the single-channel photovoltaic input unit 102 to change from an on state to an off state, physically cutting off the electrical connection. For an internal short circuit, the shutdown of the shutdown switch module 1024 prevents the high voltage from continuing to impact the downstream battery components; for an external short circuit, the shutdown of the shutdown switch module 1024 prevents the reverse discharge of energy from the battery 104.

[0064] In some embodiments, the off switch module 1024 may optionally be a parallel combination of a relay and a semiconductor switch, wherein the mechanical switch of the relay is responsible for carrying static current to reduce losses, and the semiconductor switch is responsible for rapid disconnection to improve the control efficiency of the off switch module 1024 in closing.

[0065] In some embodiments, voltage detection may be achieved via a resistive voltage divider network and an analog-to-digital converter, or via an isolated voltage sensor, to improve the accuracy of voltage detection in the photovoltaic energy storage power conversion system 100.

[0066] In some embodiments, the current direction detection can optionally determine the voltage direction by detecting the voltage difference through a series sampling resistor and a differential amplifier, or by directly acquiring the current value through a current sensor, so as to improve the adaptability of current direction detection in different usage environments or business scenarios.

[0067] In some embodiments, the determination of exceeding the threshold can be optionally achieved through hardware instantaneous determination using a comparator circuit, or through determination by a software algorithm after periodically sampling the values ​​in the analog-to-digital converter by a control unit, such as a microcontroller unit. The software determination incorporates more complex logic, such as delay confirmation and filtering algorithms.

[0068] In some embodiments, optionally, such as Figure 4 As shown, the shutdown switch module 1024 includes a first field-effect transistor MOS1 and a second field-effect transistor MOS2; the source of the first field-effect transistor MOS1 and the source of the second field-effect transistor MOS2 are connected; the drain of the first field-effect transistor MOS1 is connected to the positive terminal of the photovoltaic input port 1022; and the drain of the second field-effect transistor MOS2 is connected to the input terminal of the buck circuit 1026.

[0069] In this embodiment, the shutdown switch module 1024 protects a specific circuit structure consisting of a first field-effect transistor MOS1 and a second field-effect transistor MOS2 connected back-to-back in a common-source manner. The connection between the source of the first field-effect transistor MOS1 and the source of the second field-effect transistor MOS2 utilizes the reverse series connection of the body diodes inside the two field-effect transistors to achieve bidirectional controllable conduction and shutdown of the current. This provides a hardware basis for fault isolation that can simultaneously and effectively block forward fault current and reverse discharge current, ensuring the reliability of fault isolation operation.

[0070] In this circuit, the drain of the first field-effect transistor MOS1 is connected to the positive terminal of the photovoltaic input port 1022, forming one port of the switch; the drain of the second field-effect transistor MOS2 is connected to the input terminal of the buck circuit 1026, forming the other port of the switch.

[0071] When conduction is required, the system applies a sufficiently high forward voltage to the gates of both the first MOSFET MOS1 and the second MOSFET MOS2 simultaneously. At this time, both MOSFET MOS1 and MOSFET MOS2 will conduct, and current will flow from the photovoltaic input port 1022 to the buck circuit 1026.

[0072] When it is necessary to turn off, the drive voltage of the gates of the first field-effect transistor MOS1 and the second field-effect transistor MOS2 is removed, and both the first field-effect transistor MOS1 and the second field-effect transistor MOS2 switch from the on state to the off state. Regardless of the direction of the voltage difference between the two drains, this structure can reliably block the current.

[0073] In some embodiments, the first field-effect transistor MOS1 and the second field-effect transistor MOS2 may optionally include, but are not limited to, a metal-oxide-semiconductor field-effect transistor (MOSFET), a junction field-effect transistor (JFET), or an insulated-gate bipolar transistor (IGBT). Options can be made in terms of drive voltage, switching speed, and current capacity by selecting different devices.

[0074] In some embodiments, optionally, the first field-effect transistor MOS1 and the second field-effect transistor MOS2 are discretely packaged devices, with their source pins connected together via wires or copper foil on an external circuit board; alternatively, the first field-effect transistor MOS1 and the second field-effect transistor MOS2 are integrated within the same semiconductor package to achieve a common-source connection. This can be a multi-chip module, thereby reducing parasitic parameters and improving performance.

[0075] In some embodiments, optionally, such as Figure 4 As shown, the shutdown switch module 1024 further includes: a first driving component 10242, the control signal output terminal of the first driving component 10242 is connected to the drain of the first field-effect transistor MOS1, the control signal output terminal of the first driving component 10242 is connected to the drain of the second field-effect transistor MOS2, and the first driving component 10242 is used to turn off or close the shutdown switch module 1024.

[0076] In this embodiment, the control signal output terminal of the first driving component 10242 is connected to the gates of the first field-effect transistor MOS1 and the second field-effect transistor MOS2, respectively, thereby realizing the precise control of the switching state of the turn-off switch module 1024 by the driving signal, and ensuring that the fault isolation command can be quickly executed by the first field-effect transistor MOS1 and the second field-effect transistor MOS2.

[0077] The first driving component 10242 includes a control unit circuit or control unit chip, designed to convert and amplify weak logic signals from an upstream control unit, such as a microcontroller, into strong electrical signals capable of rapidly driving the gates of the first field-effect transistor MOS1 and the second field-effect transistor MOS2.

[0078] When the switching module 1024 needs to be turned on or off, the system control unit determines that one photovoltaic input unit 102 needs to be turned on and sends a high-level logic signal to the first driving component 10242. After receiving the high-level logic signal, the first driving component 10242 immediately generates a sufficiently high gate driving voltage at the control signal output terminal and applies it to the gates of the first field-effect transistor MOS1 and the second field-effect transistor MOS2 respectively. The first field-effect transistor MOS1 and the second field-effect transistor MOS2 are turned on, and the path from the photovoltaic input to the step-down circuit 1026 is established.

[0079] When the turn-off switch module 1024 needs to be turned off, the control unit can determine that at least one photovoltaic input unit 102 has failed and needs to be isolated. The control unit sends a low-level or turn-off logic signal to the first drive component 10242. The first drive component 10242 quickly removes or pulls down the gate voltage of the first field-effect transistor MOS1 and the second field-effect transistor MOS2, turning off the first field-effect transistor MOS1 and the second field-effect transistor MOS2, thereby cutting off the fault path.

[0080] For example, the first driving component 10242 is a highly integrated half-bridge or dual-channel driving chip, or a driving circuit built from discrete components (such as transistors, totem-pole circuits, pulse transformers, etc.).

[0081] In some embodiments, optionally, such as Figure 5 As shown, the photovoltaic energy storage power conversion system 100 also includes a photovoltaic module 108, which is connected to the photovoltaic input port 1022.

[0082] In this embodiment, the energy source of the photovoltaic energy storage power conversion system 100 is further defined. The connection between the external energy source and the internal conversion device is formed by connecting the photovoltaic module 108 and the photovoltaic input port 1022.

[0083] For example, the photovoltaic module 108 directly converts solar energy into direct current.

[0084] The positive and negative terminals of the photovoltaic module 108 are respectively connected to the positive and negative terminals of the photovoltaic input port 1022. The DC power generated by the photovoltaic module 108 is injected into the photovoltaic energy storage power conversion system 100 through at least one photovoltaic input port 1022 and stored in the battery 104 of the photovoltaic energy storage power conversion system 100.

[0085] In some embodiments, optionally, what is connected to a photovoltaic input port 1022 can be a single photovoltaic module 108, or an array formed by multiple photovoltaic modules 108 connected in series, or by multiple photovoltaic modules 108 connected in parallel and then in series.

[0086] In some embodiments, the photovoltaic module 108 may be directly connected to the photovoltaic input port 1022 via cables and connectors, or an optimizer or micro-inverter may be connected between the photovoltaic module 108 and the photovoltaic input port 1022.

[0087] In some embodiments, the photovoltaic module 108 may be a separate unit, i.e., the conversion system is a separate chassis connected to a distant photovoltaic array via external cables, or it may be an integrated photovoltaic energy storage unit integrated with the conversion system.

[0088] In some embodiments, optionally, such as Figure 9 As shown, the photovoltaic energy storage power conversion system 100 also includes a battery management component 110, which is connected to the battery 104 and is used to manage the state parameters of the battery 104.

[0089] In this embodiment, the battery management component 110 connects to the battery 104 to intelligently sense, monitor, and manage the state parameters of the battery 104 in a refined manner. This enhances the reliability of fault diagnosis through accurate feedback of battery 104 data and constructs a safety protection barrier for the battery 104 itself, thereby improving the safety of the entire photovoltaic energy storage power conversion system 100.

[0090] The battery management component 110 is directly connected to the battery 104 via a wiring harness to collect parameters such as voltage, current and temperature.

[0091] The battery management component 110 continuously collects the status parameters of the battery 104. If an extreme abnormality is detected in the battery 104 (such as severe overvoltage or short circuit), even if the main controller of the photovoltaic energy storage power conversion system 100 fails to act in time, the battery management component 110 will act as the last line of defense, controlling the internal or external contactor to disconnect, completely cutting off the connection between the battery 104 and the system, and preventing the accident from escalating.

[0092] In some embodiments, optionally, such as Figure 6 and Figure 7As shown, the step-down circuit 1026 includes: a first switching transistor Q1, the drain of which is connected to the turn-off switch module 1024; a second switching transistor Q2, the drain of which is connected to the source of which is connected to the source of which is connected to the source of which is connected to the negative terminal of the photovoltaic input port 1022; and an inductor C2, the first terminal of which is the switching node between the source of which is connected to the source of which is connected to the source of which is connected to the drain ...

[0093] In this embodiment, the step-down circuit 1026 includes a first switch Q1, a second switch Q2, and an inductor C2. The source of the first switch Q1 and the drain of the second switch Q2 are connected, and the inductor C2 is connected to the switching node between the first switch Q1 and the second switch Q2, providing an efficient and reliable step-down rectification function for the photovoltaic energy storage power conversion system 100.

[0094] Specifically, the drain of the first switching transistor Q1 is used as the input terminal of the step-down circuit 1026 and connected to the output of the turn-off switch module 1024. The source of the second switching transistor Q2 is connected to ground and shares ground with the negative terminal of the photovoltaic input port 1022 and the negative terminal of the battery 104.

[0095] The source of the first switching transistor Q1 and the drain of the second switching transistor Q2 are connected at a single point, which is the switching node.

[0096] The step-down circuit 1026 reduces the higher photovoltaic input voltage to the battery 104 voltage by controlling the alternating conduction of the first switch Q1 and the second switch Q2.

[0097] For example, the photovoltaic input voltage ranges from 30V to 80V. After being stepped down to the voltage of the battery 104 by the step-down circuit 1026, the voltage of the battery 104 ranges from 22.4V to 28.8V.

[0098] The alternating conduction of the first switch Q1 and the second switch Q2 includes: when the first switch Q1 is turned on and the second switch Q2 is turned off, the photovoltaic input voltage is applied to one end of the inductor C2, the current of the inductor C2 increases linearly, storing energy and charging the battery 104 at the same time; when the first switch Q1 is turned off and the second switch Q2 is turned on, the inductor C2 forms a freewheeling circuit through the second switch Q2, the current decreases linearly, releasing energy and continuously maintaining the power supply to the battery 104.

[0099] By precisely controlling the ratio of the conduction time of the first switch Q1 and the second switch Q2, the required battery voltage 104 can be stably output to the user.

[0100] For example, both the first switch Q1 and the second switch Q2 are MOSFETs.

[0101] Understandably, replacing the traditional freewheeling diode with the second switching transistor Q2 (synchronous MOSFET) significantly reduces the conduction loss during the freewheeling stage, thus greatly improving the conversion efficiency of the entire buck circuit 1026, since the on-resistance of the MOSFET is much lower than the on-voltage drop of the diode.

[0102] In some embodiments, the gates of the first switch Q1 and the second switch Q2 are optionally connected in series with gate resistors to suppress oscillations and are equipped with pull-down resistors to ensure stable off-state conditions.

[0103] In some embodiments, optionally, such as Figure 7 As shown, the step-down circuit 1026 also includes a capacitor C1, the first end of which is connected to the drain of the first switching transistor Q1, and the second end of which is connected to the source of the second switching transistor Q2.

[0104] In this embodiment, a capacitor C1 is connected in parallel between the drain of the first switching transistor Q1 and the source of the second switching transistor Q2 in the step-down circuit 1026. The capacitor C1 provides a stable operating voltage for the core switching circuit and effectively suppresses electromagnetic interference by providing local energy buffer and high-frequency noise bypass path, thereby significantly improving the stability, reliability and electromagnetic compatibility of the entire power conversion stage.

[0105] The first end of capacitor C1 is connected to the drain of the first switching transistor Q1, that is, connected to the input terminal of the buck circuit 1026. The second end of capacitor C1 is connected to the source of the second switching transistor Q2. The source of the second switching transistor Q2 is grounded. Therefore, capacitor C1 is connected in parallel between the input terminal of the buck circuit 1026 and ground.

[0106] In the buck converter 1026, the current demand of the first switch Q1 and the second switch Q2 is pulsed during high-frequency switching. At the instant that the first switch Q1 or the second switch Q2 is turned on, a large instantaneous current is drawn from the input terminal.

[0107] Without capacitor C1, this instantaneous current would have to be entirely supplied by the upstream photovoltaic module 108 and the shutdown switch module 1024. Due to the parasitic inductance C2 in the circuit, drastic current changes would cause large voltage spikes and noise at the input.

[0108] Understandably, capacitor C1 can provide instantaneous current quickly and nearby when the switching transistor requires a large current, thereby smoothing the input current, suppressing input voltage fluctuations, and providing a stable operating voltage for the buck circuit 1026.

[0109] Furthermore, the extremely high-frequency noise generated during the switching process of the first switch Q1 and the second switch Q2 will be radiated or conducted outward through parasitic parameters. Capacitor C1 provides a low-impedance bypass path for these high-frequency noises, so that the noise current is limited in the step-down circuit 1026, thereby improving the stability of the photovoltaic energy storage power conversion system 100.

[0110] In some embodiments, optionally, such as Figure 7 As shown, the step-down circuit 1026 further includes: a second driving component 10244, the control signal output terminal of the second driving component 10244 is connected to the gate of the first switching transistor Q1, the control signal output terminal of the second driving component 10244 is connected to the gate of the second switching transistor Q2, and the second driving component 10244 is used to control the first switching transistor Q1 and the second switching transistor Q2 to be turned on alternately.

[0111] In this embodiment, the buck circuit 1026 further includes a second driving component 10244 dedicated to the power switching transistors. By connecting the control signal output terminal of the second driving component 10244 to the gate of the first switching transistor Q1, the buck circuit 1026 is upgraded into a controllable and precisely executable power conversion unit 106. The second driving component 10244, as a key hub connecting the system control logic and the power switching action, ensures the efficient alternating conduction of the first switching transistor Q1 and the second switching transistor Q2 by providing high-speed, reliable gate drive signals and integrating hardware protection functions.

[0112] For example, the second driving component 10244 includes a half-bridge gate driving chip.

[0113] The second drive component 10244 converts and amplifies the high-voltage, high-current signal from the upstream controller and low-power logic signals, enabling it to drive the first switch Q1 and the second switch Q2 quickly and reliably.

[0114] The control signal output terminal of the second driving component 10244 is connected to the gates of the first switching transistor Q1 and the second switching transistor Q2, respectively, and the input terminal of the second driving component 10244 is used to receive the pulse width modulation signal from the system main controller.

[0115] The microcontroller unit in the system calculates the required duty cycle based on the feedback of the output voltage and generates two complementary pulse width modulation signals, which are then sent to the second drive component 10244.

[0116] The second drive component 10244 amplifies the weak pulse width modulation signal into a strong drive signal sufficient to quickly turn the first switch Q1 and the second switch Q2 on and off.

[0117] When the first switch Q1 is turned on, the second drive component 10244 applies a high voltage to the gate of the first switch Q1, while ensuring that the gate of the second switch Q2 is at a low voltage, i.e., in the off state.

[0118] After a very short dead time (to prevent the first switch Q1 and the second switch Q2 from being short-circuited due to simultaneous conduction), the second drive component 10244 turns off the first switch Q1 and then turns on the second switch Q2 to provide a freewheeling path for the inductor C2.

[0119] Through high-speed alternation, a square wave voltage with an adjustable duty cycle is generated at the switching node of inductor C2. After being filtered by inductor C2, a smooth DC output with a voltage lower than the input voltage is obtained.

[0120] Understandably, the second drive component 10244 provides a clean, powerful, and fast drive waveform, which ensures that the switching transistor can switch quickly between the saturation and cutoff regions, minimizing switching and conduction losses.

[0121] In some embodiments, optionally, such as Figure 8 As shown, the conversion unit 106 includes: a resonant converter 1062, the input terminal of which is connected to the battery 104; and an inverter 1064, the DC input terminal of which is connected to the output terminal of the resonant converter 1062, the AC output terminal of which is connected to an AC port, and connected to the AC power grid or load 300 through the AC port.

[0122] In this embodiment, the conversion unit 106 is a two-stage architecture consisting of a resonant converter 1062 and an inverter 1064. The resonant converter 1062 is responsible for achieving electrical isolation and efficient DC-DC conversion at the input of the battery 104 terminal, while the inverter 1064 is responsible for generating grid-connected or off-grid AC power in a coordinated working relationship.

[0123] The two-stage architecture consisting of resonant converter 1062 and inverter 1064 achieves extremely high conversion efficiency through the soft-switching technology of resonant converter 1062 and ensures system safety through electrical isolation. At the same time, it provides a stable DC bus for inverter 1064, thereby achieving high power density, high-quality AC output and optimization of the working environment of battery 104 as a whole.

[0124] The resonant converter 1062 primarily performs DC-DC conversion. Its core function is to receive DC power from the battery 104, which has a wide voltage range, and then perform a secondary conversion.

[0125] The resonant converter 1062 achieves electrical isolation between the battery 104 side (primary side) and the grid side (secondary side) through a high-frequency transformer, preventing DC high voltage from entering the AC grid.

[0126] Furthermore, the resonant converter 1062 enables the switching transistor to operate under zero-voltage turn-on and / or zero-current turn-off conditions through the resonance of inductor C2 and capacitor C1, which greatly reduces switching losses and achieves high-frequency, high-efficiency power conversion.

[0127] Inverter 1064 converts the stable DC power output from resonant converter 1062 into sinusoidal AC power that meets the requirements of the power grid.

[0128] By controlling multiple switching transistors, such as MOSFETs, to alternately conduct in a high-frequency pulse modulation manner, the DC current is chopped into a pulse voltage with a simulated sine wave. Then, the high-frequency components are filtered out by a filter to obtain a smooth sine alternating current.

[0129] The DC input terminal of inverter 1064 is connected to the output terminal of resonant converter 1062, and the AC output terminal of inverter 1064 is connected to the AC port. Sinusoidal AC power is supplied to the household load 300 or fed back to the grid through the AC port.

[0130] In one specific embodiment, optionally, such as Figure 4 As shown, a pair of MOSFETs, MOS1 and MOS2, are added to the PV2 input port.

[0131] During normal operation, MOS1 and MOS2 are turned on, and their internal resistance is approximately 2 milliohms. At a maximum current of 14A, the total power dissipation of the two MOS transistors is 14 × 14 × 0.004 = 0.224W. The heat generation is very small, and its impact on the overall system efficiency is negligible.

[0132] When the upper MOSFET of PV2 is short-circuited and shoots through, MOSFETs MOS1 and MOS2 are turned off. At this time, there is no voltage input to PV2, and the other three PV channels can operate normally.

[0133] When a short circuit occurs in the external PV2 photovoltaic panel, MOS transistors MOS1 and MOS2 are turned off. This prevents BAT+ from outputting current through the upper MOS body diode of PV2, while the other three PV channels can operate normally.

[0134] One embodiment of this application also provides a fault isolation method for the photovoltaic energy storage power conversion system of the first aspect. The photovoltaic energy storage power conversion system includes multiple photovoltaic input units, batteries, and conversion units. The photovoltaic input units include a photovoltaic input port, a shutdown switch module, and a step-down circuit, such as... Figure 10 As shown, the fault isolation methods include:

[0135] Step S100: Obtain the first state parameters of the buck circuit and the second state parameters of the photovoltaic input port in the multiple photovoltaic input units;

[0136] Step S102: Obtain the battery voltage parameters;

[0137] Step S104: Identify at least one faulty photovoltaic input unit based on the first state parameter, the second state parameter, and the voltage parameter;

[0138] Step S106: Control the shutdown switch module in the faulty photovoltaic input unit to shut down;

[0139] When the shutdown switch module in at least one faulty photovoltaic input unit is turned off, and the faulty photovoltaic input unit and the battery are electrically isolated, the remaining at least one photovoltaic input unit continues to operate.

[0140] This application provides a fault isolation method for photovoltaic energy storage power conversion systems. By continuously acquiring and comprehensively analyzing the circuit state parameters and battery voltage parameters of each photovoltaic input unit, it intelligently diagnoses and accurately locates the specific photovoltaic input unit that has failed. Then, it selectively shuts down the shutdown switch module in the faulty unit, electrically isolating it from the system bus, while ensuring that the remaining normal photovoltaic input units continue to work. This achieves a fundamental transformation of the system from shutdown upon failure to derating operation during failure, significantly improving the availability and reliability of the system.

[0141] Specifically, the first state parameters include the input and output voltages of the buck circuit, the waveforms of the switching nodes, or the circuit health status estimated by an algorithm. These are used to determine whether the buck circuit itself is operating normally.

[0142] The second status parameter directly monitors the condition of the photovoltaic module side, including port voltage, input current magnitude and direction. It is used to determine whether the external photovoltaic module and wiring are functioning properly.

[0143] The battery voltage parameters are a key reference for the DC side of the system. Abnormalities in battery voltage (such as a sudden increase) are an indicator of whether high voltage has entered from the fault point.

[0144] When the photovoltaic energy storage power conversion system detects an abnormal increase in battery voltage, it does not directly determine that the entire system is faulty. Instead, it combines the first state parameters of each circuit to pinpoint which specific step-down circuit has a short circuit, causing its input high voltage to be directly applied to the battery bus.

[0145] When a sudden drop in voltage to near zero is detected at a photovoltaic input port, and current flowing from the battery to that port is also detected, it can be determined that an external short circuit has occurred in the photovoltaic panel or cable on the corresponding route.

[0146] Once a faulty unit is identified, the actuators, namely the first and second drive components, are immediately triggered. Control commands selectively shut down the shutdown switch module in the faulty unit, rather than cutting off the entire system. That is, when the shutdown switch module in at least one faulty photovoltaic input unit is turned off, and the faulty photovoltaic input unit and the battery are electrically isolated, at least one other photovoltaic input unit continues to operate.

[0147] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0148] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., 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 invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0149] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to specific features, structures, materials, or characteristics described in connection with an embodiment or example that are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0150] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A photovoltaic energy storage power conversion system, characterized by, The application relates to a photovoltaic power supply system, comprising: a plurality of photovoltaic input units, each comprising a photovoltaic input port, a shutdown switch module and a step-down circuit, wherein the positive electrode of the photovoltaic input port is connected to the input end of the step-down circuit through the shutdown switch module; a battery, the positive electrode of which is connected to the output end of the step-down circuit, and the negative electrode of which is connected to the negative electrode of the photovoltaic input port; a conversion unit, the direct-current input end of which is connected to the battery, and the alternating-current output end of which is used for connecting to an alternating-current power grid or a load; wherein the shutdown switch module is configured to determine that the step-down circuit has a short-circuit fault and shut down the shutdown switch module when it is detected that the voltage of the step-down circuit exceeds a first preset voltage threshold value; or determine that the photovoltaic input port has an external short circuit and shut down the shutdown switch module when it is detected that the voltage of the photovoltaic input port is lower than a second preset voltage threshold value and there is a current flowing from the battery bus to the photovoltaic input port. The shutdown switch module comprises a first field effect transistor and a second field effect transistor; 2. The photovoltaic energy storage power conversion system of claim 1, wherein, the source electrode of the first field effect transistor is connected to the source electrode of the second field effect transistor; the drain electrode of the first field effect transistor is connected to the positive electrode of the photovoltaic input port; the drain electrode of the second field effect transistor is connected to the input end of the step-down circuit. The shutdown switch module further comprises:

3. The photovoltaic energy storage power conversion system of claim 2, wherein, a first driving assembly, the control signal output end of which is connected to the drain electrode of the first field effect transistor and the drain electrode of the second field effect transistor, and which is used for controlling the shutdown or closure of the shutdown switch module. The application further comprises:

4. The photovoltaic energy storage power conversion system of claim 1, wherein, a photovoltaic assembly, which is connected to the photovoltaic input port. The application further comprises:

5. The photovoltaic energy storage power conversion system of claim 4, wherein, a battery management assembly, which is connected to the battery and is used for managing the state parameters of the battery. The step-down circuit comprises:

6. The photovoltaic energy storage power conversion system of claim 4, wherein, a first switch tube, the drain electrode of which is connected to the shutdown switch module; a second switch tube, the drain electrode of which is connected to the source electrode of the first switch tube, and the source electrode of which is connected to the negative electrode of the photovoltaic input port; an inductor, the first end of which is connected to a switch node between the source electrode of the first switch tube and the drain electrode of the second switch tube, and the second end of which is connected to the positive electrode of the battery. The step-down circuit further comprises:

7. The photovoltaic energy storage power conversion system of claim 6, wherein, a capacitor, the first end of which is connected to the drain electrode of the first switch tube, and the second end of which is connected to the source electrode of the second switch tube. The step-down circuit further comprises:

8. The photovoltaic energy storage power conversion system of claim 6, wherein, a second driving assembly, the control signal output end of which is connected to the gate electrode of the first switch tube and the gate electrode of the second switch tube, and which is used for controlling the first switch tube and the second switch tube to be alternately turned on. The conversion unit comprises:

9. The photovoltaic energy storage power conversion system of claim 1, wherein, a resonant converter, the input end of which is connected to the battery; ​ An inverter, a DC input of the inverter being connected to an output of the resonant converter, an AC output of the inverter being connected to an AC port, and an AC grid or a load being connected through the AC port.

10. A method of fault isolation, characterized by, The method for fault isolation of a photovoltaic energy storage power conversion system as claimed in any one of claims 1 to 9, the photovoltaic energy storage power conversion system comprising a plurality of photovoltaic input units, a battery and a conversion unit, the photovoltaic input unit comprising a photovoltaic input port, an off switch module and a buck circuit, the method comprising: acquiring a first state parameter of the buck circuit and a second state parameter of the photovoltaic input port of the plurality of photovoltaic input units; acquiring a voltage parameter of the battery; identifying at least one faulty photovoltaic input unit according to the first state parameter, the second state parameter and the voltage parameter; controlling the off switch module of the faulty photovoltaic input unit to be off; wherein when the off switch module of at least one faulty photovoltaic input unit is off, the faulty photovoltaic input unit and the battery are electrically isolated, and the remaining at least one photovoltaic input unit continues to operate.

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