Photovoltaic inverter circuit, inverter and system

Abstract

The utility model discloses a photovoltaic inverter circuit, an inverter and a system, and the photovoltaic inverter circuit comprises a frequency conversion circuit; a multi-path short-circuit protection circuit; the multi-path boost circuit comprises at least two boost modules, each boost module comprises at least two boost circuits, and the output ends of all the boost modules are cascaded and connected with the input end of the frequency conversion circuit; the positive input end of each booster circuit is used for being connected with the positive electrode of a photovoltaic module, the negative input end of each booster circuit is connected with the negative electrode of the photovoltaic module through a short-circuit protection circuit, and the positive electrode connected with the positive input end of each booster circuit and the negative electrode connected with the negative input end of each booster circuit through the short-circuit protection circuit belong to the same photovoltaic module; wherein each short-circuit protection circuit is used for stopping outputting the current of the negative electrode of the connected photovoltaic module to the negative input end of the booster circuit. According to the technical scheme of the utility model, the inverter can be protected when the non-isolated string type photovoltaic inverter is short-circuited to the ground.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaic short-circuit protection to ground, and in particular to a photovoltaic inverter circuit, an inverter and a system. Background Art

[0002] With the increasing application of photovoltaic (PV) energy, the safety of PV power plants and the stability of PV inverters are receiving increasing attention. Traditionally, grounding anomalies at the PV module end are typically detected through insulation impedance testing. However, this insulation impedance testing function is ineffective when non-isolated string PV inverters are connected to the grid for grid-connected operation. Therefore, a short-circuit to ground can easily short-circuit the grid through the inverter, ultimately causing inverter failure. Utility Model Content

[0003] The main purpose of the utility model is to provide a photovoltaic inverter circuit, which aims to solve the problem that a non-isolated string photovoltaic inverter is prone to inverter failure when short-circuited to the ground.

[0004] To achieve the above-mentioned purpose, the present invention proposes a photovoltaic inverter circuit, which includes:

[0005] Frequency conversion circuit;

[0006] Multiple short-circuit protection circuits; and

[0007] A multi-channel boost circuit, wherein the multi-channel boost circuit includes at least two boost modules, each of which includes at least two boost circuits, and the output ends of all the boost modules are cascaded and connected to the input end of the frequency conversion circuit; the positive input end of each boost circuit is used to connect to the positive electrode of a photovoltaic module, and the negative input end of each boost circuit is connected to the negative electrode of the photovoltaic module via one of the short-circuit protection circuits, and the positive electrode connected to the positive input end of each boost circuit and the negative electrode connected to the negative input end via the short-circuit protection circuit belong to the same photovoltaic module;

[0008] Each of the short-circuit protection circuits is used to stop outputting the current of the negative electrode of the connected photovoltaic component to the negative input terminal of the boost circuit.

[0009] Optionally, the short-circuit protection circuit includes:

[0010] A one-way flow device, wherein the first end and the second end of the one-way flow device are connected one-to-one with the negative pole of the photovoltaic component and the negative input end of the boost circuit; the current direction of the one-way flow device is from the second end to the first end.

[0011] Optionally, the short-circuit protection circuit includes:

[0012] a switch circuit, a first end of which is connected to the negative input terminal of the boost circuit, and a second end of which is connected to the negative electrode of the photovoltaic module;

[0013] a driving circuit, wherein a detection end is connected to the negative input end of the boost circuit or the negative electrode of the photovoltaic module, and a control end is connected to the controlled end of the switch circuit; the driving circuit is configured to drive the switch circuit to connect the negative input end of the boost circuit and the negative electrode of the photovoltaic module when it is detected that the current direction of the detection end is the same as the preset current direction; and to drive the switch circuit to disconnect the negative input end of the boost circuit from the negative electrode of the photovoltaic module when the current direction of the detection end is different from the preset current direction;

[0014] The preset current direction is from the negative input end of the boost circuit to the negative electrode of the photovoltaic module.

[0015] Optionally, the number of the boost circuits and the short-circuit protection circuits is 3N, and each of the boost modules includes three boost circuits;

[0016] Among them, N≥2.

[0017] Optionally, the photovoltaic inverter circuit further includes N first control switches and N second control switches;

[0018] The positive input terminal of each boost circuit is connected to the positive electrode of a photovoltaic module through a first control switch;

[0019] Each of the short-circuit protection circuits is connected to the negative pole of a photovoltaic module via a second control switch; or the negative input terminal of each of the boost circuits is connected to the short-circuit protection circuit via a second control switch.

[0020] Optionally, all the first control switches in each of the boost modules are joint control switches;

[0021] And / or, all the second control switches in each of the boost modules are joint control switches.

[0022] The present invention also provides a photovoltaic inverter, which includes the photovoltaic inverter circuit as described above, and is used to be connected to a photovoltaic module.

[0023] Optionally, the photovoltaic inverter includes an inverter body;

[0024] If each short-circuit protection circuit in the photovoltaic inverter circuit is connected to the negative pole of a photovoltaic module through a second control switch, then all boost circuits, all short-circuit protection circuits, and frequency conversion circuits in the photovoltaic inverter circuit are arranged in the inverter body, and all the second control switches in the photovoltaic inverter circuit are arranged outside the inverter body.

[0025] Optionally, the photovoltaic inverter includes an inverter body;

[0026] If the negative input end of each boost circuit in the photovoltaic inverter circuit is connected to the short-circuit protection circuit through a second control switch, all boost circuits and frequency conversion circuits in the photovoltaic inverter circuit are arranged in the inverter body, and all the short-circuit protection circuits and all the second control switches in the photovoltaic inverter circuit are arranged outside the inverter body.

[0027] The present invention further provides a photovoltaic system, comprising:

[0028] at least one photovoltaic module; and,

[0029] The photovoltaic inverter circuit or the photovoltaic inverter described above is used to be connected to each of the photovoltaic modules.

[0030] The technical solution of the present utility model adopts a short-circuit protection circuit provided between the negative electrode of each photovoltaic module and the negative input terminal of the boost circuit. When a current is output from the negative electrode of the photovoltaic module to the negative input terminal of the boost circuit, the short-circuit protection circuit disconnects the current transmission path between the negative electrode of the photovoltaic module and the negative input terminal of the boost circuit to prevent the current from flowing to the boost circuit, thereby disconnecting the short-circuit loop to the ground formed by the negative electrode of the photovoltaic module and the inverter, thereby solving the problem of the body diode exploding under the action of the current and causing inverter failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0032] Figure 1 This is a schematic structural diagram of an embodiment of a photovoltaic inverter circuit of the present utility model;

[0033] Figure 2 This is a schematic diagram of the current flow in a traditional photovoltaic inverter circuit when a short circuit to ground occurs at the negative pole of a photovoltaic module;

[0034] Figure 3 This is a circuit diagram of a short-circuit protection circuit in an embodiment of a photovoltaic inverter circuit of the present utility model;

[0035] Figure 4 This is a circuit diagram of a short-circuit protection circuit in another embodiment of the photovoltaic inverter circuit of the present utility model;

[0036] Figure 5 This is a schematic structural diagram of an embodiment of a photovoltaic inverter of the present utility model;

[0037] Figure 6 This is a schematic structural diagram of another embodiment of the photovoltaic inverter of the present utility model.

[0038] Description of Figure Numbers:

[0039]

[0040] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] In addition, in this utility model, the descriptions of "first" and "second" are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this utility model.

[0043] The utility model provides a photovoltaic inverter circuit.

[0044] Reference Figures 1 to 2 In one embodiment, the photovoltaic inverter circuit includes:

[0045] Frequency conversion circuit 10;

[0046] Multiple short-circuit protection circuit 20; and

[0047] A multi-channel boost circuit 30 includes at least two boost modules 40, each of which includes at least two boost circuits 30. The outputs of all boost modules 40 are connected in cascade to the input of the frequency conversion circuit 10. The positive input of each boost circuit 30 is used to connect to the positive electrode of a photovoltaic module 50, and the negative input of each boost circuit 30 is connected to the negative electrode of the photovoltaic module 50 via a short-circuit protection circuit 20. The positive electrode connected to the positive input of each boost circuit 30 and the negative electrode connected to the negative input of each boost circuit 30 via the short-circuit protection circuit 20 belong to the same photovoltaic module 50.

[0048] Each short-circuit protection circuit 20 is used to stop outputting the current of the negative electrode of the connected photovoltaic assembly 50 to the negative input terminal of the boost circuit 30 .

[0049] In this embodiment, the number of the short-circuit protection circuits 20 may be the same as the number of the boost circuits 30 .

[0050] The boost circuit 30 can be implemented using an inductor, a capacitor, and a switch, wherein the switch can be implemented using a MOS tube or an IGBT. The input end of the frequency conversion circuit 10 includes a positive input end and a negative input end. The frequency conversion circuit 10 can be composed of a DC-DC circuit, a bus capacitor, and a DC-AC circuit. The frequency conversion circuit 10 can receive all DC voltages output by all boost circuits 30, and can invert the received DC voltage into an AC voltage and then output it to the power grid for grid-connected operation. The DC-DC circuit and the DC-AC circuit in the frequency conversion circuit 10 can both be constructed using IGBTs. Figure 2 The embodiment shown shows an inverter circuit constructed using IGBT ( Figure 2 QA1~QA4, QB1~QB4, QC1~QC4 are all IGBTs). It is understandable that since IGBTs have body diodes and their circuit structure is non-isolated, once a short-circuit fault occurs to the ground in the non-isolated string-type photovoltaic inverter during grid-connected operation, the grid will be short-circuited through the body diodes (caused by the Figure 2 As can be seen from the current path shown, the short-circuit current will pass through the body diode of the IGBT, eventually causing the IGBT to explode and the inverter to fail.

[0051] In this embodiment, the number of boost circuits 30 included in each boost module 40 can be the same or different, which is not limited in this application, but the number of boost circuits 30 in each boost module 40 is at least two. Figure 1In the illustrated embodiment, each boost module 40 includes two boost circuits 30. For each boost module 40, the positive outputs of all boost circuits 30 are interconnected to form the positive output of the boost module 40, and the negative outputs of all boost circuits 30 are interconnected to form the negative output of the boost module 40. The positive output of the first boost module 40 is connected to the positive input of the frequency conversion circuit 10, and the negative output of the last boost module 40 is connected to the negative input of the frequency conversion circuit 10. The positive output of each intermediate boost module 40 is connected to the negative output of the previous boost module 40, and the negative output of each intermediate boost module 40 is connected to the positive output of the next boost module 40. This achieves a cascaded output connection for all boost modules 40, forming a serial structure.

[0052] It can be understood that the positive and negative input terminals of each boost circuit 30 are connected to the positive and negative terminals of the same photovoltaic module 50. Therefore, in this embodiment, the number of photovoltaic modules 50, the number of short-circuit protection circuits 20, and the number of boost circuits 30 required to be connected to the photovoltaic inverter circuit are all equal.

[0053] It should be noted that when the negative electrode of the photovoltaic module 50 is not short-circuited to the ground, the direction of the current between the negative electrode of the photovoltaic module 50 and the negative input terminal of the boost circuit 30 is from the negative input terminal of the boost circuit 30 to the negative electrode of the photovoltaic module 50. At this time, no short-circuit loop to the ground is formed between the photovoltaic module 50 and the boost circuit 30. When a short circuit to the ground occurs, such as Figure 2 As shown, the current direction is opposite, that is, the current direction between the negative electrode of the photovoltaic component 50 and the negative input terminal of the boost circuit 30 is from the negative electrode of the photovoltaic component 50 to the negative input terminal of the boost circuit 30.

[0054] In this embodiment, the short-circuit protection circuit 20 can disconnect the current transmission path between the negative electrode of the photovoltaic component 50 and the negative input terminal of the boost circuit 30 when a current is output from the negative electrode of the photovoltaic component 50 to the negative input terminal of the boost circuit 30, so as to prevent the current from flowing to the boost circuit 30, thereby disconnecting the short-circuit loop to the ground formed by the negative electrode of the photovoltaic component 50 and the inverter, thereby solving the problem of the body diode bursting under the action of this current and causing inverter failure.

[0055] It can be understood that when a current is output from the negative input end of the boost circuit 30 to the negative pole of the photovoltaic component 50, the short-circuit protection circuit 20 does not disconnect the current transmission path between the two, so that the current can be normally output to the negative pole of the photovoltaic component 50 to form a normal current loop.

[0056] Reference Figure 3 In one embodiment, the short circuit protection circuit 20 includes:

[0057] The one-way flow device 21 has a first end and a second end that are connected one-to-one with the negative pole of the photovoltaic module 50 and the negative input end of the boost circuit 30 ; the current direction of the one-way flow device 21 is from the second end to the first end.

[0058] In an alternative embodiment, the unidirectional current flow device 21 may be a diode D1, with the cathode and anode of the diode D1 serving as the first and second terminals of the unidirectional current flow device 21, respectively. When a short-circuit to ground fault has not occurred, the unidirectional current flow device 21 normally returns the current at the negative input terminal of the boost circuit 30 to the negative terminal of the photovoltaic module 50. However, when a short-circuit to ground fault occurs, the unidirectional current flow device 21 utilizes its unidirectional current flow characteristics to prevent the current at the negative terminal of the photovoltaic module 50 from flowing to the boost circuit 30, thereby protecting the inverter.

[0059] Reference Figure 4 In one embodiment, the short circuit protection circuit 20 includes:

[0060] The switch circuit 22 has a first end connected to the negative input terminal of the boost circuit 30 and a second end connected to the negative terminal of the photovoltaic module 50;

[0061] The driving circuit 23 has a detection end connected to the negative input end of the boost circuit 30 or the negative pole of the photovoltaic component 50, and a control end connected to the controlled end of the switch circuit 22; the driving circuit 23 is used to drive the switch circuit 22 to connect the negative input end of the boost circuit 30 and the negative pole of the photovoltaic component 50 when it is detected that the current direction of the detection end is the same as the preset current direction; and is used to drive the switch circuit 22 to disconnect the negative input end of the boost circuit 30 from the negative pole of the photovoltaic component 50 when the current direction of the detection end is different from the preset current direction.

[0062] The preset current direction is from the negative input terminal of the boost circuit 30 to the negative electrode of the photovoltaic assembly 50 .

[0063] The switch circuit 22 can be composed of switching devices such as transistors, MOS transistors, IGBTs, optocouplers, and relays. The drive circuit 23 can be composed of a main controller and a resistor device. The main controller can be implemented using an MCU, FPGA, DSP, or CPU main control chip. The resistor device constitutes the detection terminal of the drive circuit 23 and can be located between the negative input terminal of the boost circuit 30 and the switch circuit 22, or between the switch circuit 22 and the negative terminal of the photovoltaic module 50. The main controller can obtain the voltage value across the resistor device to determine the direction of the current flowing from the negative input terminal of the boost circuit 30 to the negative terminal of the photovoltaic module 50.

[0064] Here, the triggering logic of the switch circuit 22 is described using the example of a resistor device disposed between the negative input terminal of the boost circuit 30 and the switch circuit 22. The end of the resistor device connected to the switch circuit 22 is defined as the first end, while the end connected to the negative input terminal of the boost circuit 30 is defined as the second end. If the main controller detects that the voltage value at the second end of the resistor device is greater than that at the first end, this indicates that the current is flowing from the negative input terminal of the boost circuit 30 to the negative terminal of the photovoltaic module 50, meaning that a short-circuit to ground has not occurred. The switch circuit 22 is then maintained conductive to connect the negative input terminal of the boost circuit 30 and the negative terminal of the photovoltaic module 50. If the main controller detects that the voltage value at the second end of the resistor device is less than that at the first end, this indicates that the current is flowing from the photovoltaic module 50 to the negative input terminal of the negative boost circuit 30, meaning that a short-circuit to ground has occurred. The switch circuit 22 is then driven to shut down, disconnecting the negative input terminal of the boost circuit 30 from the negative terminal of the photovoltaic module 50.

[0065] In this way, the technical solution of the present invention detects the direction of current flow, and when the driving circuit 23 detects the direction of current flow from the negative pole of the photovoltaic component 50 to the negative input end of the boost circuit 30, it drives the switching circuit 22 to actively disconnect the transmission path of the short-circuit current, thereby realizing active protection of the inverter.

[0066] Reference Figures 5 and 6 The number of the boost circuits 30 and the short-circuit protection circuits 20 is 3N, and each boost module 40 includes three boost circuits 30, and each boost module 40 includes three boost circuits 30; wherein N≥2.

[0067] In this embodiment, each boost module 40 is connected to three photovoltaic modules 50, and each boost module 40 can boost the voltage output by three photovoltaic modules 50 before outputting it. It is understandable that in this embodiment, the number of boost modules 40 is N.

[0068] Optionally, the photovoltaic inverter circuit further includes N first control switches S1 and N second control switches S2;

[0069] The positive input terminal of each boost circuit 30 is connected to the positive electrode of a photovoltaic module 50 through a first control switch S1;

[0070] Each short-circuit protection circuit 20 is connected to the negative electrode of a photovoltaic assembly 50 through a second control switch S2; or, the negative input terminal of each boost circuit 30 is connected to the short-circuit protection circuit 20 through a second control switch S2.

[0071] With this configuration, by controlling the corresponding first control switch S1 to be on / off, the connection or disconnection between the positive input terminal of the corresponding boost circuit 30 and the positive terminal of the photovoltaic module 50 can be actively controlled, thereby achieving input control of any boost circuit 30. It will be understood that when the first control switch S1 is off, the boost circuit 30 corresponding to the first control switch S1 has no voltage input, and the voltage connected to the frequency conversion circuit 10 will also decrease accordingly. Therefore, by controlling the conduction / off state of each first control switch S1, the output of the frequency conversion circuit 10 can be controlled.

[0072] In this embodiment, there are two configuration methods for the second control switch S2. The first configuration method (eg Figure 5 As shown) is set between the short-circuit protection circuit 20 and the negative electrode of the photovoltaic component 50; the second setting method (as shown) Figure 6 ) is arranged between the negative input terminal of the boost circuit 30 and the short-circuit protection circuit 20.

[0073] With this configuration, by controlling the corresponding second control switch S2 to be on / off, the connection or disconnection between the negative input terminal of the corresponding boost circuit 30 and the negative terminal of the photovoltaic module 50 can be actively controlled, thereby achieving input control of any boost circuit 30. It will be understood that when the second control switch S2 is off, the boost circuit 30 corresponding to the second control switch S2 has no voltage input, and the voltage connected to the frequency conversion circuit 10 will also decrease accordingly. Therefore, by controlling the conduction / off state of each second control switch S2, the output of the inverter can be controlled.

[0074] When the photovoltaic inverter circuit is provided with both the first control switch S1 and the second control switch S2 , the first control switch S1 and the second control switch S2 may be provided as redundancies to improve the compatibility of the input control of the frequency conversion circuit 10 .

[0075] Optionally, all the first control switches S1 in each of the boost modules 40 are joint control switches;

[0076] And / or, all the second control switches S2 in each of the boost modules 40 are joint control switches.

[0077] In this embodiment, the three first control switches S1 in each boost module 40 are synchronously turned on or off, and the three second control switches S2 in each boost module 40 are also synchronously turned on or off. This helps simplify the complexity of the input control for each boost module 40.

[0078] The present invention also provides a photovoltaic inverter, which includes a photovoltaic inverter circuit. The specific structure of the photovoltaic inverter circuit is similar to that of the aforementioned embodiments. Since the present photovoltaic inverter utilizes all the technical solutions of all the aforementioned embodiments, it at least has all the beneficial effects brought about by the technical solutions of the aforementioned embodiments, and therefore will not be described in detail here. The photovoltaic inverter is configured to connect to a photovoltaic module 50.

[0079] Reference Figure 5 In one embodiment, the photovoltaic inverter includes an inverter body 60;

[0080] If each short-circuit protection circuit 20 is connected to the negative pole of a photovoltaic module 50 through a second control switch S2, then all the boost circuits 30, all the short-circuit protection circuits 20, and the frequency conversion circuit 10 in the photovoltaic inverter circuit are arranged in the inverter body 60, and all the second control switches S2 in the photovoltaic inverter circuit are arranged outside the inverter body 60.

[0081] In this embodiment, all the second control switches S2 adopt the first configuration mode. In this case, all the short-circuit protection circuits 20 can be disposed in the inverter body, and only all the second control switches S2 are disposed outside the inverter body 60 .

[0082] Reference Figure 6 In one embodiment, the photovoltaic inverter includes an inverter body 60;

[0083] If the negative input terminal of each boost circuit 30 is connected to the short-circuit protection circuit 20 through a second control switch S2, all boost circuits 30 and frequency conversion circuits 10 in the photovoltaic inverter circuit are arranged in the inverter body 60, and all short-circuit protection circuits 20 and all second control switches S2 in the photovoltaic inverter circuit are arranged outside the inverter body 60.

[0084] In this embodiment, all second control switches S2 adopt the second configuration method, which is different from the first configuration method in that all short-circuit protection circuits 20 and all second control switches S2 can be disposed outside the inverter body 60 .

[0085] Of course, if the photovoltaic inverter circuit further includes the first control switch S1 , all first control switches S1 are arranged outside the inverter body 60 regardless of the first or second arrangement of the second control switch S2 .

[0086] The present invention also provides a photovoltaic system, comprising a photovoltaic module 50 and a photovoltaic inverter circuit, or a photovoltaic module 50 and a photovoltaic inverter. The specific structures of the photovoltaic inverter circuit and the photovoltaic inverter are similar to those of the aforementioned embodiments. Since the present photovoltaic system utilizes all the technical solutions of all the aforementioned embodiments, it at least has all the beneficial effects brought about by the technical solutions of the aforementioned embodiments, and therefore will not be described in detail here. The photovoltaic inverter circuit or photovoltaic inverter is used to connect to each photovoltaic module 50, and the number of photovoltaic modules 50 can be the same as the number of boost circuits 30.

[0087] The above are merely optional embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made based on the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, within the inventive concept of the present invention, are included in the patent protection scope of the present invention.

Claims

1. A photovoltaic inverter circuit, characterized in that: The photovoltaic inverter circuit includes: Frequency conversion circuit; Multiple short-circuit protection circuits; and A multi-channel boost circuit, wherein the multi-channel boost circuit includes at least two boost modules, each of which includes at least two boost circuits, and the output ends of all the boost modules are cascaded and connected to the input end of the frequency conversion circuit; the positive input end of each boost circuit is used to connect to the positive electrode of a photovoltaic module, and the negative input end of each boost circuit is connected to the negative electrode of the photovoltaic module via one of the short-circuit protection circuits, and the positive electrode connected to the positive input end of each boost circuit and the negative electrode connected to the negative input end via the short-circuit protection circuit belong to the same photovoltaic module; Each of the short-circuit protection circuits is used to stop outputting the current of the negative electrode of the connected photovoltaic component to the negative input terminal of the boost circuit.

2. The photovoltaic inverter circuit according to claim 1, characterized in that: The short-circuit protection circuit comprises: A one-way flow device, wherein the first end and the second end of the one-way flow device are connected one-to-one with the negative pole of the photovoltaic component and the negative input end of the boost circuit; the current direction of the one-way flow device is from the second end to the first end.

3. The photovoltaic inverter circuit according to claim 1, wherein: The short-circuit protection circuit comprises: a switch circuit, a first end of which is connected to the negative input terminal of the boost circuit, and a second end of which is connected to the negative electrode of the photovoltaic module; a driving circuit, wherein a detection end is connected to the negative input end of the boost circuit or the negative electrode of the photovoltaic module, and a control end is connected to the controlled end of the switch circuit; the driving circuit is configured to drive the switch circuit to connect the negative input end of the boost circuit and the negative electrode of the photovoltaic module when it is detected that the current direction of the detection end is the same as the preset current direction; and to drive the switch circuit to disconnect the negative input end of the boost circuit from the negative electrode of the photovoltaic module when the current direction of the detection end is different from the preset current direction; The preset current direction is from the negative input end of the boost circuit to the negative electrode of the photovoltaic module.

4. The photovoltaic inverter circuit according to claim 1, wherein: The number of the boost circuits and the short-circuit protection circuits is 3N, and each of the boost modules includes three boost circuits; Among them, N≥2.

5. The photovoltaic inverter circuit according to claim 4, characterized in that: The photovoltaic inverter circuit further includes N first control switches and N second control switches; The positive input terminal of each boost circuit is connected to the positive electrode of a photovoltaic module through a first control switch; Each of the short-circuit protection circuits is connected to the negative pole of a photovoltaic module via a second control switch; or the negative input terminal of each of the boost circuits is connected to the short-circuit protection circuit via a second control switch.

6. The photovoltaic inverter circuit according to claim 5, characterized in that: All the first control switches in each of the boost modules are joint control switches; And / or, all the second control switches in each of the boost modules are joint control switches.

7. A photovoltaic inverter, characterized in that: The photovoltaic inverter comprises the photovoltaic inverter circuit according to any one of claims 1 to 6, and the photovoltaic inverter is used to be connected to a photovoltaic module.

8. The photovoltaic inverter according to claim 7, characterized in that: The photovoltaic inverter includes an inverter body; If each short-circuit protection circuit in the photovoltaic inverter circuit is connected to the negative pole of a photovoltaic module through a second control switch, then all boost circuits, all short-circuit protection circuits, and frequency conversion circuits in the photovoltaic inverter circuit are arranged in the inverter body, and all the second control switches in the photovoltaic inverter circuit are arranged outside the inverter body.

9. The photovoltaic inverter according to claim 7, wherein: The photovoltaic inverter includes an inverter body; If the negative input end of each boost circuit in the photovoltaic inverter circuit is connected to the short-circuit protection circuit through a second control switch, all boost circuits and frequency conversion circuits in the photovoltaic inverter circuit are arranged in the inverter body, and all the short-circuit protection circuits and all the second control switches in the photovoltaic inverter circuit are arranged outside the inverter body.

10. A photovoltaic system, characterized in that: The photovoltaic system comprises: at least one photovoltaic module; and The photovoltaic inverter circuit according to any one of claims 1 to 6 or the photovoltaic inverter according to any one of claims 7 to 9, wherein the photovoltaic inverter circuit or the photovoltaic inverter is configured to be connected to each of the photovoltaic modules.

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