Photovoltaic optimizer capable of supporting backward irrigation voltage to detect hidden cracks of photovoltaic module and working method of photovoltaic optimizer

Abstract

The invention provides a photovoltaic optimizer supporting backward flowing voltage detection photovoltaic module subfissure, the photovoltaic optimizer comprises an input end and an output end, the input end is connected with the output end of a photovoltaic module, and the output end is connected with the output end of the photovoltaic module. The photovoltaic optimizer further comprises a first switching tube, a second switching tube, a switching tube synchronous driving unit, an output voltage sampling unit and an enabling unit, and when the photovoltaic optimizer is started, the enabling unit detects whether voltage is applied to the output end of the photovoltaic optimizer through the output voltage sampling unit and determines whether an enabling signal is generated; the switching tube synchronous driving unit synchronously controls the switching frequency of the first switching tube and the switching frequency of the second switching tube through enabling signals so that the photovoltaic module can work at the maximum power point. According to the invention, the optimizer can bear reverse voltage, so that the optimizer can support photovoltaic panel electroluminescent crack detection without disassembly.

Description

Technical Field

[0001] The present invention relates to the photovoltaic field, and in particular to a photovoltaic optimizer and a working method thereof that supports backflow voltage detection of hidden cracks in photovoltaic components. Background Art

[0002] Photovoltaic modules, as the core components of solar photovoltaic systems, have a direct impact on the power generation efficiency and service life of the entire system due to their performance and reliability. During the production, transportation, installation and operation of photovoltaic modules, various defects and damages may occur, among which cracks are one of the most common and most destructive problems. Cracks will not only reduce the electrical performance of photovoltaic modules, but may also cause more serious physical damage, thus affecting the stable operation of the entire photovoltaic system. Therefore, it is particularly important to detect cracks in photovoltaic modules.

[0003] Electroluminescence (EL) detection technology is an efficient method for detecting cracks in photovoltaic modules. The basic principle is to apply reverse voltage to the photovoltaic module to cause the semiconductor material inside the photovoltaic module to produce electroluminescence. Normal photovoltaic modules will emit light evenly during the electroluminescence process, while areas with cracks or other defects will show obvious abnormal light emission. Specifically, these abnormalities usually manifest as reduced brightness or no light emission, which can intuitively show the specific location and shape of the crack.

[0004] The output power of photovoltaic modules is affected by many factors such as light intensity, temperature, load conditions, etc., and its output characteristics show a nonlinear relationship. Under specific environmental conditions, photovoltaic modules have a unique operating point that maximizes their output power. This point is called the maximum power point (MPP). In order to make the photovoltaic system always work at the maximum power point and improve the power generation efficiency, MPPT technology came into being. MPPT is actually a DC-DC Buck step-down circuit that adjusts the output voltage by adjusting the switching frequency of the upper MOSFET tube.

[0005] Photovoltaic optimizers are a common product form of MPPT. The output of the photovoltaic module is connected to the input of the optimizer. The optimizer output is connected in series with the optimizer outputs of other photovoltaic modules to form a string connected to the inverter. When performing electroluminescent crack detection, a reverse voltage is applied to both ends of the string. For strings equipped with photovoltaic optimizers, the reverse voltage is directly applied to the output of the optimizer, causing the MOSFET in the optimizer DC-DC Buck circuit to be broken down. Summary of the invention

[0006] In view of the problems existing in the prior art, a photovoltaic optimizer and a working method supporting backfeed voltage detection of hidden cracks in photovoltaic components are provided, which can effectively prevent the switch tube in the optimizer DC-DC Buck circuit from being broken down.

[0007] A first aspect of the present invention provides a photovoltaic optimizer that supports backflow voltage detection of hidden cracks in photovoltaic modules, the photovoltaic optimizer comprising an input terminal and an output terminal, wherein the input terminal is connected to the output terminal of the photovoltaic module; the photovoltaic optimizer comprises:

[0008] A first switch tube, having a first end, a second end and a control end, wherein the first end of the first switch tube is connected to the output end of the photovoltaic component; the second end of the first switch tube is connected to the output end of the photovoltaic optimizer via an inductor; the control end of the first switch tube is connected to the switch synchronization driving unit to receive a first control signal;

[0009] A second switch tube has a first end, a second end and a control end, wherein the first end of the second switch tube is connected to the second end of the first switch tube; the second end of the second switch tube is grounded; and the control end of the second switch tube is connected to the switch synchronization driving unit to receive a second control signal;

[0010] The switch tube synchronous driving unit receives the enable signal of the main control chip and generates a first control signal and a second control signal; wherein the first control signal and the second control signal are in anti-phase;

[0011] An output voltage sampling unit is connected to the output terminal of the photovoltaic optimizer and is used to generate a sampling voltage; the sampling voltage is used to characterize the voltage at the output terminal of the photovoltaic optimizer;

[0012] The enabling unit is used to determine whether to generate an enabling signal according to the sampling voltage output by the output voltage sampling unit when the photovoltaic optimizer is started.

[0013] As a preferred solution, the switch tube synchronous driving unit includes an inverter, a first AND gate and a second AND gate, wherein:

[0014] The first input ends of the first AND gate and the second AND gate receive the enable signal respectively; the externally provided PWN signal is respectively input to the second input end of the first AND gate and the input end of the inverter, and the output end of the inverter is connected to the second input end of the second AND gate to receive the PWM signal; the output end of the first AND gate outputs the first control signal, and the output end of the second AND gate outputs the second control signal.

[0015] As a preferred solution, the output voltage sampling unit includes a first resistor, a second resistor and a first capacitor, wherein:

[0016] The first end of the first resistor is connected to the output end of the photovoltaic optimizer, and the second end of the first resistor is grounded via the second resistor; the first capacitor is connected in parallel with the second resistor; and the common node of the first resistor and the second resistor outputs the sampling voltage.

[0017] As a preferred solution, it also includes a second capacitor, wherein the negative electrode of the second capacitor is connected to the output terminal of the photovoltaic optimizer, and the positive electrode is grounded.

[0018] As a preferred solution, it also includes a PWM signal generating unit, which is used to control the output of a PWM signal of a desired waveform, and the PWM signal is used to adjust the switching frequency of the switch tube to find the maximum power point of the photovoltaic component output.

[0019] As a preferred solution, the first switch tube and the second switch tube are NMOS tubes, the first ends of the first switch tube and the second switch tube are drains, the second ends of the first switch tube and the second switch tube are sources, and the control ends of the first switch tube and the second switch tube are gates.

[0020] As a preferred solution, the enabling unit detects whether the output voltage sampling unit outputs a sampling voltage each time the photovoltaic optimizer is started, and generates an enabling signal if the sampling voltage does not exist.

[0021] The second aspect of the present invention provides a working method of a photovoltaic optimizer supporting backflow voltage detection of photovoltaic module hidden cracks based on the first aspect, comprising:

[0022] When the PV optimizer is powered on, the output voltage sampling power supply is used to detect whether there is voltage at the output end of the PV optimizer;

[0023] If it does not exist, the switch tube synchronous driving unit is enabled to output the first control signal and the second control signal to control the first switch tube and the second switch tube to work respectively; if it exists, the switch tube synchronous driving unit does not work.

[0024] As a preferred solution, when the photovoltaic optimizer is powered on, if there is no voltage at the output end, it means that the photovoltaic optimizer receives the forward voltage at the input end. At this time, the switch tube synchronous driving unit outputs the first control signal and the second control signal to adjust the switching frequency of the first switch tube and the second switch tube to find the maximum power point.

[0025] As a preferred solution, when the photovoltaic optimizer is powered on, if there is a voltage at the output end, it means that the photovoltaic optimizer receives the feedback voltage at the output end. At this time, the switch tube synchronous drive unit is not enabled, the first switch tube and the second switch tube are turned off at the same time, and the second end of the first switch tube is regarded as a forward diode with the first end. The received feedback voltage flows to the first end through the second end of the first switch tube and is applied to the photovoltaic component through the input end of the photovoltaic optimizer.

[0026] Compared with the prior art, the beneficial effect of adopting the above technical solution is that the photovoltaic optimizer proposed in the present invention can work normally when the backfeed voltage is applied, so that the photovoltaic optimizer can perform electroluminescent crack detection without being disassembled. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of a photovoltaic optimizer proposed by the present invention that supports backflow voltage detection of hidden cracks in photovoltaic modules.

[0028] Figure 2 This is a schematic diagram of the operation when a voltage is applied to the input terminal of a photovoltaic optimizer in one embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of the operation when a voltage is applied to the output end of a photovoltaic optimizer in one embodiment of the present invention. DETAILED DESCRIPTION

[0030] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar modules or modules with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be construed as limitations on the present application. On the contrary, the embodiments of the present application include all changes, modifications and equivalents that fall within the spirit and connotation of the appended claims.

[0031] In order to solve the problem that when the photovoltaic optimizer is installed in the photovoltaic module and electroluminescent crack detection is performed, the reverse voltage applied at both ends of the string causes the photovoltaic optimizer to be broken and damaged, an embodiment of the present invention provides a photovoltaic optimizer that supports backflow voltage detection of hidden cracks in photovoltaic modules, and can support switching between electroluminescent crack detection or normal output power regulation. The photovoltaic optimizer includes an input end and an output end, and its input end is connected to the output end of the photovoltaic module, and the output power of the photovoltaic module can be adjusted, and the output is completed at the output end. In an actual photovoltaic system, each photovoltaic module can be equipped with a photovoltaic optimizer, and the string is completed through the output end of the photovoltaic optimizer.

[0032] Please refer to Figure 1The photovoltaic optimizer includes a first switch tube, a second switch tube, a switch tube synchronous driving unit, an output voltage sampling unit and an enabling unit. Specifically, the first switch tube has a first end, a second end and a control end, the first end of the first switch tube is connected to the output end of the photovoltaic component; the second end of the first switch tube is connected to the output end of the photovoltaic optimizer through an inductor; the control end of the first switch tube is connected to the switch synchronous driving unit to receive a first control signal; the second switch tube has a first end, a second end and a control end, the first end of the second switch tube is connected to the second end of the first switch tube; the second end of the second switch tube is grounded; the control end of the second switch tube is connected to the switch synchronous driving unit to receive a second control signal; the switch tube synchronous driving unit receives the enabling signal of the main control chip and generates a first control signal and a second control signal; wherein the first control signal is inversely proportional to the second control signal; the output voltage sampling unit is connected to the output end of the photovoltaic optimizer to generate a sampling voltage; the sampling voltage is used to characterize the voltage at the output end of the photovoltaic optimizer; the enabling unit is used to determine whether to generate an enabling signal according to the sampling voltage output by the output voltage sampling unit when the photovoltaic optimizer is started. It also includes a second capacitor, wherein the negative electrode of the second capacitor is connected to the output end of the photovoltaic optimizer, and the positive electrode is grounded.

[0033] Please continue to refer to Figure 1 An embodiment of the present invention provides a specific implementation method of a switch tube synchronous driving unit, which mainly includes an inverter, a first AND gate and a second AND gate, wherein the first input ends of the first AND gate and the second AND gate respectively receive the enable signal; the externally provided PWN signal is respectively input to the second input end of the first AND gate and the input end of the inverter, and the output end of the inverter is connected to the second input end of the second AND gate to receive the PWM signal; the output end of the first AND gate outputs the first control signal, and the output end of the second AND gate outputs the second control signal.

[0034] Through the switch tube synchronous driving unit, the enable signal can be controlled to ensure that when the photovoltaic optimizer is powered on, the first switch tube and the second switch tube are in the off state at the same time, so as to perform the subsequent judgment process.

[0035] In this embodiment, the first control signal and the second control signal generated by the switch tube synchronous driving unit are generated by the same PWM signal, and the difference between the two is that the second control signal is inverted by the inverter.

[0036] In one embodiment, the photovoltaic optimizer further includes a PWM signal generating unit, which can output a PWM signal of a desired waveform according to control. The PWM signal can adjust the switching frequency of the first switch tube and the second switch tube to find the maximum power point of the photovoltaic component output.

[0037] Please continue to refer to Figure 1The output voltage sampling unit includes a first resistor, a second resistor and a first capacitor, wherein the first end of the first resistor is connected to the output end of the photovoltaic optimizer, and the second end of the first resistor is grounded via the second resistor; the first capacitor is connected in parallel with the second resistor; and the common node of the first resistor and the second resistor outputs the sampling voltage.

[0038] In this embodiment, two voltage-dividing resistors are connected in series between the output terminal and the ground, and the voltage between the two resistors is selected as the voltage detection point, and the voltage at this point is sampled by the ADC of the main control chip. It should be noted that the resistance values ​​of the two voltage-dividing resistors can be adjusted so that the voltage value of the detection point is within the measurement range of the ADC, and then the conversion formula can be used to obtain the corresponding voltage value.

[0039] In this embodiment, the enabling unit determines whether to generate an enabling signal based on whether the photovoltaic optimizer detects the presence of voltage at the output terminal when starting up. That is, when the presence of voltage at the output terminal is detected, the enabling signal is not generated; when the presence of voltage at the output terminal is not detected, the enabling signal is generated.

[0040] It should be noted that the first switch tube and the second switch tube are controllable electronic switching devices, and any suitable semiconductor switching device can be selected, such as a metal oxide semiconductor field effect transistor (Metal Oxide Semiconductor Field Effect Transistor, MOSFET) or a bipolar transistor (Bipolar Junction Transistor, BJT) or a junction field effect transistor (Junction Field Effect Transistor, JFET), etc. In this specification, the first switch tube and the second switch tube are both illustrated by MOS tubes, that is, metal oxide semiconductor field effect tubes.

[0041] In this embodiment, the first switch tube and the second switch tube are NMOS tubes, the first end of the first switch tube and the second switch tube is a drain, the second end of the first switch tube and the second switch tube is a source, and the control end of the first switch tube and the second switch tube is a gate.

[0042] In order to better explain the working mode of the photovoltaic optimizer, this embodiment also provides a working method of the photovoltaic optimizer that supports backflow voltage detection of photovoltaic module hidden cracks, including:

[0043] When the PV optimizer is powered on, the output voltage sampling power supply is used to detect whether there is voltage at the output end of the PV optimizer;

[0044] If it does not exist, the switch tube synchronous driving unit is enabled to output the first control signal and the second control signal to control the first switch tube and the second switch tube to work respectively; if it exists, the switch tube synchronous driving unit does not work.

[0045] When voltage is applied to the input or output of the photovoltaic optimizer, the enabling unit works first. At this time, the enabling unit turns off the driving enable of the first switch tube and the second switch tube, that is, no enable signal is output to the switch tube synchronization driving unit at this time. The first switch tube and the second switch tube are both in the off state, and then the output voltage is detected by the output voltage sampling unit.

[0046] Please refer to Figure 2 When the photovoltaic optimizer is started, if the voltage comes from the input end, at this time, the switch tube synchronous driving unit is not enabled, the first switch tube is in a non-conducting state, and the current cannot flow to the output end through the first switch tube, then no voltage value will be measured at the output end. In other words, when no voltage is measured at the output end, it generally means that there is a positive phase voltage at the input end. At this time, the photovoltaic optimizer works normally, the enabling unit generates an enabling signal, controls the switch tube synchronous driving unit to output the first control signal and the second control signal, and adjusts the switching frequency of the first switch tube and the second switch tube to find the maximum power point.

[0047] Please refer to Figure 3 When the photovoltaic optimizer is started, if the voltage comes from this output end, the voltage will be directly applied to the voltage-dividing resistor at this time, and the output voltage sampling unit can detect the existence of voltage at the output end. In other words, when the voltage is measured at the output end, it generally means that the output end has input a reverse voltage, and electroluminescent crack detection needs to be performed. At this time, the second switch tube must be closed to prevent the reverse applied voltage from being greater than the maximum withstand voltage between the first and second ends of the switch tube, resulting in breakdown damage. Therefore, when it is detected that the output end is applied with a reverse voltage, the enabling unit does not work, the first switch tube and the second switch tube are turned off at the same time, and the second end of the first switch tube is regarded as a forward diode with the first end. The reverse voltage flows to the first end through the second end of the first switch tube, and can be applied to the photovoltaic module through the input end of the photovoltaic optimizer, ensuring that the electroluminescent crack detection of the photovoltaic panel is successfully completed.

[0048] The photovoltaic optimizer proposed in the present invention can be made to withstand reverse voltage, so that it supports electroluminescent crack detection of photovoltaic panels without disassembly.

[0049] Example 1

[0050] This embodiment provides a photovoltaic optimizer that supports backflow voltage detection of photovoltaic module hidden cracks. The photovoltaic optimizer includes an input end and an output end, wherein the input end is connected to the output end of the photovoltaic module; the photovoltaic optimizer includes:

[0051] A first switch tube, having a first end, a second end and a control end, wherein the first end of the first switch tube is connected to the output end of the photovoltaic component; the second end of the first switch tube is connected to the output end of the photovoltaic optimizer via an inductor; the control end of the first switch tube is connected to the switch synchronization driving unit to receive a first control signal;

[0052] A second switch tube has a first end, a second end and a control end, wherein the first end of the second switch tube is connected to the second end of the first switch tube; the second end of the second switch tube is grounded; and the control end of the second switch tube is connected to the switch synchronization driving unit to receive a second control signal;

[0053] The switch tube synchronous driving unit receives the enable signal of the main control chip and generates a first control signal and a second control signal; wherein the first control signal and the second control signal are in anti-phase;

[0054] An output voltage sampling unit is connected to the output terminal of the photovoltaic optimizer and is used to generate a sampling voltage; the sampling voltage is used to characterize the voltage at the output terminal of the photovoltaic optimizer;

[0055] The enabling unit is used to determine whether to generate an enabling signal according to the sampling voltage output by the output voltage sampling unit when the photovoltaic optimizer is started.

[0056] Example 2

[0057] On the basis of Embodiment 1, the switch tube synchronous driving unit in this embodiment includes an inverter, a first AND gate and a second AND gate, wherein:

[0058] The first input ends of the first AND gate and the second AND gate receive the enable signal respectively; the externally provided PWN signal is respectively input to the second input end of the first AND gate and the input end of the inverter, and the output end of the inverter is connected to the second input end of the second AND gate to receive the PWM signal; the output end of the first AND gate outputs the first control signal, and the output end of the second AND gate outputs the second control signal.

[0059] Example 3

[0060] On the basis of Embodiment 2, the output voltage sampling unit in this embodiment includes a first resistor, a second resistor and a first capacitor, wherein:

[0061] The first end of the first resistor is connected to the output end of the photovoltaic optimizer, and the second end of the first resistor is grounded via the second resistor; the first capacitor is connected in parallel with the second resistor; and the common node of the first resistor and the second resistor outputs the sampling voltage.

[0062] Example 4

[0063] On the basis of embodiment 1, this embodiment further includes a second capacitor, wherein the negative electrode of the second capacitor is connected to the output terminal of the photovoltaic optimizer, and the positive electrode is grounded.

[0064] Example 5

[0065] On the basis of Example 2, this embodiment further includes a PWM signal generating unit for controlling the output of a PWM signal of a desired waveform, wherein the PWM signal is used to adjust the switching frequency of the switch tube to find the maximum power point of the photovoltaic module output.

[0066] Example 6

[0067] Based on the first embodiment, in this embodiment, the first switch tube and the second switch tube are NMOS tubes, the first end of the first switch tube and the second switch tube is a drain, the second end of the first switch tube and the second switch tube is a source, and the control end of the first switch tube and the second switch tube is a gate.

[0068] Example 7

[0069] On the basis of Embodiment 1, the enabling unit in this embodiment detects whether the output voltage sampling unit outputs a sampling voltage each time the photovoltaic optimizer is started, and generates an enabling signal if the sampling voltage does not exist.

[0070] Example 8

[0071] This embodiment provides a working method of a photovoltaic optimizer supporting backflow voltage detection of photovoltaic module hidden cracks based on the first aspect, including:

[0072] When the PV optimizer is powered on, the output voltage sampling power supply is used to detect whether there is voltage at the output end of the PV optimizer;

[0073] If it does not exist, the switch tube synchronous driving unit is enabled to output the first control signal and the second control signal to control the first switch tube and the second switch tube to work respectively; if it exists, the switch tube synchronous driving unit does not work.

[0074] Example 9

[0075] On the basis of Example 8, when the photovoltaic optimizer described in this embodiment is powered on, if there is no voltage at the output end, it means that the photovoltaic optimizer receives the forward voltage at the input end. At this time, the switch tube synchronous driving unit outputs the first control signal and the second control signal, and adjusts the switching frequency of the first switch tube and the second switch tube to find the maximum power point.

[0076] Example 10

[0077] On the basis of Example 8, when the photovoltaic optimizer described in this embodiment is powered on, if there is a voltage at the output end, it means that the photovoltaic optimizer receives the feedback voltage at the output end. At this time, the switch tube synchronous drive unit is not enabled, the first switch tube and the second switch tube are turned off at the same time, and the second end of the first switch tube is regarded as a forward diode with the first end. The received feedback voltage flows to the first end through the second end of the first switch tube and is applied to the photovoltaic module through the input end of the photovoltaic optimizer.

[0078] The present invention can be better implemented through Examples 1 to 10.

[0079] It should be noted that in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "setting" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances; the drawings in the embodiments are used to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations.

[0080] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A photovoltaic optimizer that supports backflow voltage detection of photovoltaic module cracks, characterized in that: The photovoltaic optimizer comprises an input end and an output end, wherein the input end is connected to the output end of the photovoltaic module; the photovoltaic optimizer further comprises: A first switch tube, having a first end, a second end and a control end, wherein the first end of the first switch tube is connected to the output end of the photovoltaic component; the second end of the first switch tube is connected to the output end of the photovoltaic optimizer via an inductor; the control end of the first switch tube is connected to the switch synchronization driving unit to receive a first control signal; A second switch tube has a first end, a second end and a control end, wherein the first end of the second switch tube is connected to the second end of the first switch tube; the second end of the second switch tube is grounded; and the control end of the second switch tube is connected to the switch synchronization driving unit to receive a second control signal; The switch tube synchronous driving unit receives the enable signal of the main control chip and generates a first control signal and a second control signal; wherein the first control signal and the second control signal are in anti-phase; An output voltage sampling unit is connected to the output terminal of the photovoltaic optimizer and is used to generate a sampling voltage; the sampling voltage is used to characterize the voltage at the output terminal of the photovoltaic optimizer; The enabling unit is used to determine whether to generate an enabling signal according to the sampling voltage output by the output voltage sampling unit when the photovoltaic optimizer is started.

2. The photovoltaic optimizer supporting backflow voltage detection of photovoltaic module hidden cracks according to claim 1 is characterized in that: The switch tube synchronous driving unit includes an inverter, a first AND gate and a second AND gate, wherein: The first input ends of the first AND gate and the second AND gate receive the enable signal respectively; the externally provided PWN signal is respectively input to the second input end of the first AND gate and the input end of the inverter, and the output end of the inverter is connected to the second input end of the second AND gate to receive the PWM signal; the output end of the first AND gate outputs the first control signal, and the output end of the second AND gate outputs the second control signal.

3. The photovoltaic optimizer supporting backflow voltage detection of photovoltaic module hidden cracks according to claim 1 or 2, characterized in that: The output voltage sampling unit includes a first resistor, a second resistor and a first capacitor, wherein: The first end of the first resistor is connected to the output end of the photovoltaic optimizer, and the second end of the first resistor is grounded via the second resistor; the first capacitor is connected in parallel with the second resistor; and the common node of the first resistor and the second resistor outputs the sampling voltage.

4. The photovoltaic optimizer supporting backflow voltage detection of photovoltaic module hidden cracks according to claim 1, characterized in that: It also includes a second capacitor, wherein the negative electrode of the second capacitor is connected to the output end of the photovoltaic optimizer, and the positive electrode is grounded.

5. The photovoltaic optimizer supporting backflow voltage detection of photovoltaic module hidden cracks according to claim 2, characterized in that: It also includes a PWM signal generating unit, which is used to control the output of a PWM signal of a desired waveform, and the PWM signal is used to adjust the switching frequency of the switch tube to find the maximum power point of the photovoltaic component output.

6. The photovoltaic optimizer supporting backflow voltage detection of photovoltaic module hidden cracks according to claim 1, characterized in that: The first switch tube and the second switch tube are NMOS tubes, the first ends of the first switch tube and the second switch tube are drains, the second ends of the first switch tube and the second switch tube are sources, and the control ends of the first switch tube and the second switch tube are gates.

7. The photovoltaic optimizer supporting backflow voltage detection of photovoltaic module hidden cracks according to claim 1, characterized in that: The enabling unit detects whether the output voltage sampling unit outputs a sampling voltage each time the photovoltaic optimizer is started, and generates an enabling signal if the sampling voltage does not exist.

8. A working method of a photovoltaic optimizer supporting backflow voltage detection of photovoltaic module hidden cracks based on any one of claims 1 to 7, characterized in that: include: When the PV optimizer is powered on, the output voltage sampling power supply is used to detect whether there is voltage at the output end of the PV optimizer; If it does not exist, the switch tube synchronous driving unit is enabled to output the first control signal and the second control signal to control the first switch tube and the second switch tube to work respectively; if it exists, the switch tube synchronous driving unit does not work.

9. The working method of the photovoltaic optimizer supporting backflow voltage detection of photovoltaic module hidden cracks according to claim 8, characterized in that: When the photovoltaic optimizer is powered on, if there is no voltage at the output end, it means that the photovoltaic optimizer receives the forward voltage at the input end. At this time, the switch tube synchronous driving unit outputs the first control signal and the second control signal to adjust the switching frequency of the first switch tube and the second switch tube to find the maximum power point.

10. The working method of the photovoltaic optimizer supporting backflow voltage detection of photovoltaic module hidden cracks according to claim 8, characterized in that: When the photovoltaic optimizer is powered on, if there is a voltage at the output end, it means that the photovoltaic optimizer receives the feedback voltage at the output end. At this time, the switch tube synchronous driving unit is not enabled, the first switch tube and the second switch tube are turned off at the same time, and the second end of the first switch tube is regarded as a forward diode with the first end. The received feedback voltage flows to the first end through the second end of the first switch tube and is applied to the photovoltaic component through the input end of the photovoltaic optimizer.

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