Photovoltaic inverter and photovoltaic power generation system

Abstract

The present application provides a photovoltaic inverter and a photovoltaic power generation system. In the photovoltaic inverter, since the two poles of the first side of the power converter are respectively connected to the two ends of the first bypass switch, when the first bypass switch is disconnected, the photovoltaic cluster is connected to the DC side of the DC / AC converter through the first side of the power converter; and since the first bypass switch is turned off when the output voltage of the photovoltaic cluster decreases, when the output voltage of the photovoltaic cluster decreases, the photovoltaic cluster is connected to the DC side of the DC / AC converter through the first side of the power converter; further, since the power converter performs power conversion to its first side when the output voltage of the photovoltaic cluster decreases, that is, there is a voltage on the first side of the power converter, the output voltage of the photovoltaic cluster can be appropriately increased; therefore, the degree of decrease in the output voltage of the photovoltaic cluster can be suppressed, so that the photovoltaic inverter can alleviate the impact of the sudden decrease in the output voltage of the photovoltaic cluster on the power grid.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a photovoltaic inverter and a photovoltaic power generation system. Background Art

[0002] As a new type of energy that is pollution-free, loss-free and sustainable, solar energy has developed rapidly in recent years. At present, photovoltaic power generation is connected to the distribution network system in large quantities, which has also changed the traditional operation mode of the power grid.

[0003] As we all know, large-capacity photovoltaic inverters are mostly primary topology structures, that is, the DC side of the DC / AC converter in the photovoltaic inverter is directly connected to the photovoltaic cluster. Therefore, when the output voltage of the photovoltaic cluster suddenly drops, the DC side voltage of the DC / AC converter also drops suddenly, which in turn generates a current shock to the power grid. If the sudden drop is severe, it may even affect the normal operation of the DC / AC converter, that is, the phenomenon of abandoned light may occur.

[0004] Therefore, how to alleviate the impact of a sudden drop in the output voltage of a photovoltaic cluster on the power grid is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the present invention provides a photovoltaic inverter and a photovoltaic power generation system to alleviate the impact of a sudden drop in output voltage of a photovoltaic cluster on a power grid.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] On one hand, the present application provides a photovoltaic inverter, comprising: a DC / AC converter, a first bypass switch, a power converter and a controller; wherein:

[0008] The first bypass switch is connected in series with the photovoltaic cluster, and the two poles of the series branch formed are respectively connected to the two poles of the DC side of the DC / AC converter;

[0009] The first side of the power converter is a DC side, and the two poles of the first side of the power converter are respectively connected to the two ends of the first bypass switch;

[0010] The first bypass switch and the power converter are controlled by the controller, and the controller is used to control the first bypass switch to be disconnected and control the power converter to perform power conversion to its first side when the output voltage of the photovoltaic cluster decreases.

[0011] Optionally, the power converter is an isolated converter, the second side of the power converter is a DC side, and two poles of the second side of the power converter are respectively connected to two poles of the output end of the photovoltaic cluster.

[0012] Optionally, the power converter is an isolated converter, the second side of the power converter is a DC side, and the power converter includes: a first boost circuit, a first buck circuit, a first switch tube, a second switch tube and a first anti-reverse circuit; wherein:

[0013] The input end of the first boost circuit serves as the second side of the power converter, the output end of the first boost circuit is connected to the input end of the first buck circuit, and the output end of the first buck circuit serves as the first side of the power converter;

[0014] The first anti-reverse circuit is connected in series in the circuit between the second side positive electrode of the power converter and the first side positive electrode of the power converter along the current direction;

[0015] The first switch tube is connected in series in a circuit between the negative electrode of the input end of the first boost circuit and the negative electrode of the output end of the first boost circuit;

[0016] The second switch tube is connected in series in a circuit between the negative electrode of the input end of the first buck circuit and the negative electrode of the output end of the first buck circuit;

[0017] The first boost circuit, the first buck circuit, the first switch tube and the second switch tube are all controlled by the controller.

[0018] Optionally, the anti-reverse circuit in the first boost circuit and the first anti-reverse circuit at the same position as the first anti-reverse circuit are integrated with the first anti-reverse circuit into one anti-reverse circuit;

[0019] or,

[0020] The anti-reverse circuit in the first step-down circuit and the first anti-reverse circuit located at the same position as the first anti-reverse circuit are integrated with the first anti-reverse circuit into one anti-reverse circuit.

[0021] Optionally, the switch tube in the first boost circuit that is located at the same position as the first switch tube is integrated with the first switch tube into one switch tube;

[0022] The switch tube in the first step-down circuit that is located at the same position as the second switch tube is integrated with the second switch tube into one switch tube.

[0023] Optionally, the power converter is an isolated converter, the second side of the power converter is a DC side, and the power converter includes: a second boost circuit, a second buck circuit, a third switch tube, a fourth switch tube, a fifth switch tube and a sixth switch tube; wherein:

[0024] The input end of the second boost circuit serves as the second side of the power converter, the output end of the second boost circuit is connected to the input end of the second buck circuit, and the output end of the second buck circuit serves as the first side of the power converter;

[0025] The third switch tube is connected in series in a circuit between the positive electrode of the input end of the second boost circuit and the positive electrode of the output end of the second boost circuit;

[0026] The fourth switch tube is connected in series in a circuit between the negative electrode of the input end of the second boost circuit and the negative electrode of the output end of the second boost circuit;

[0027] The fifth switch tube is connected in series in a circuit between the positive electrode of the input end of the second buck circuit and the positive electrode of the output end of the second buck circuit;

[0028] The sixth switch tube is connected in series in a circuit between the negative electrode of the input end of the second buck circuit and the negative electrode of the output end of the second buck circuit.

[0029] Optionally, the switch tube in the second boost circuit that is located at the same position as the third switch tube is integrated with the third switch tube into one switch tube;

[0030] The switch tube in the second boost circuit that is located at the same position as the fourth switch tube is integrated with the fourth switch tube into one switch tube;

[0031] The switch tube in the second step-down circuit that is located at the same position as the fifth switch tube is integrated with the fifth switch tube into one switch tube;

[0032] The switch tube in the second step-down circuit that is located at the same position as the sixth switch tube is integrated with the sixth switch tube into one switch tube.

[0033] Optionally, the voltage-boosting circuit is a Boost circuit.

[0034] Optionally, the step-down circuit includes: a first inductor branch, a first capacitor branch and a seventh switch tube; wherein:

[0035] The first end of the first inductor branch serves as the positive electrode of the input end of the buck circuit;

[0036] The second end of the first inductor branch is connected to the first end of the first capacitor branch, and the connection point serves as the positive electrode of the output end of the buck circuit;

[0037] The second end of the first capacitor branch is connected to the input end of the seventh switch tube, and the connection point serves as the negative electrode of the output end of the buck circuit;

[0038] The output end of the seventh switch tube serves as the negative electrode of the input end of the buck circuit;

[0039] The seventh switch tube is controlled by the controller.

[0040] Optionally, it also includes: two switches; wherein:

[0041] The positive electrode of the second side of the power converter is connected to one end of the first switch, and the negative electrode of the second side of the power converter is connected to one end of the second switch;

[0042] The first switch and the second switch are both controlled by the controller, and the controller is used to control the first switch and the second switch to close before controlling the power converter to perform power conversion to the first side of the power converter.

[0043] Optionally, the photovoltaic inverter further includes: a second bypass switch; wherein:

[0044] The second bypass switch is connected in parallel with the first bypass switch;

[0045] The second bypass switch is controlled by the controller, and the controller is used to control the second bypass switch to close when the first bypass switch cannot be closed normally.

[0046] On the other hand, the present application provides a photovoltaic power generation system, characterized by comprising: a photovoltaic cluster and a photovoltaic inverter as described in any one of the previous aspects of the present application.

[0047] Optionally, the photovoltaic cluster comprises: at least two component modules connected in series; the component module comprises: a photovoltaic component, an eighth switch tube and a ninth switch tube;

[0048] In the component module, the photovoltaic component is connected in series with the eighth switch tube, the formed series branch is connected in parallel with the ninth switch tube, and the two ends of the formed parallel branch serve as the two ends of the component module respectively;

[0049] The eighth switch tube and the ninth switch tube are both controlled by a controller in the photovoltaic inverter, and the controller is used to control the eighth switch tube to turn off and the ninth switch tube to turn on when the voltage across the component module is less than a preset voltage.

[0050] It can be seen from the above technical solution that the present invention provides a photovoltaic inverter. In the photovoltaic inverter, since the two poles of the first side of the power converter are respectively connected to the two ends of the first bypass switch, when the first bypass switch is disconnected, the photovoltaic cluster is connected to the DC side of the DC / AC converter through the first side of the power converter; and since the first bypass switch is turned off when the output voltage of the photovoltaic cluster decreases, when the output voltage of the photovoltaic cluster decreases, the photovoltaic cluster is connected to the DC side of the DC / AC converter through the first side of the power converter; further, since the power converter performs power conversion to its first side when the output voltage of the photovoltaic cluster decreases, that is, there is voltage on the first side of the power converter, the output voltage of the photovoltaic cluster can be appropriately increased; therefore, the degree of reduction in the output voltage of the photovoltaic cluster can be suppressed, so that the photovoltaic inverter can alleviate the impact of the sudden reduction in the output voltage of the photovoltaic cluster on the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0052] Figure 1 A schematic diagram of the structure of an implementation scheme of a photovoltaic inverter provided in this application;

[0053] Figure 2 and Figure 3 They are schematic diagrams of the structures of two implementation modes of the power converter provided in the present application;

[0054] Figure 4 and Figure 5 Schematic diagrams of energy flow of the first boost circuit in two different situations;

[0055] Figure 6 A schematic structural diagram of another embodiment of the power converter provided in the present application;

[0056] Figure 7 and Figure 8 Schematic diagrams of energy flow of the second boost circuit in two different situations;

[0057] Fig. 9 is a schematic diagram of energy flow of a first step-down circuit;

[0058] Fig.10 A schematic structural diagram of another embodiment of the power converter provided in the present application;

[0059] Fig.11is a schematic diagram of energy flow of the second step-down circuit;

[0060] Fig.12 A schematic structural diagram of another embodiment of the power converter provided in the present application;

[0061] Fig.13 and Fig.14 They are structural schematic diagrams of two other implementation modes of the photovoltaic inverter provided in the present application;

[0062] Fig.15 This is a schematic diagram of the structure of the photovoltaic power generation system provided in this application. DETAILED DESCRIPTION

[0063] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0064] In this application, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0065] In order to alleviate the impact of a sudden drop in the output voltage of a photovoltaic cluster on the power grid, the present application embodiment provides a photovoltaic inverter, the specific structure of which can be seen in Figure 1 ( Figure 1 Only the two poles of the second side of the power converter 30 are connected to the two poles of the output end of the photovoltaic cluster 100 for display, which specifically includes: a DC / AC converter 10, a first bypass switch 20, a power converter 30 and a controller 40; the connection relationship between the various components is as follows:

[0066] The first bypass switch 20 is connected in series with the photovoltaic cluster 100 , and the two poles of the formed series branch are respectively connected to the two poles of the DC side of the DC / AC converter 10 .

[0067] It should be noted that the DC / AC converter 10 is already very mature in the prior art, and its specific structure will not be described in detail here.

[0068] Optionally, the first bypass switch 20 may be an electronic switch or a mechanical switch. In practical applications, this includes but is not limited to these. No specific limitation is made here and it may be determined according to specific circumstances. All of these are within the protection scope of this application.

[0069] Optionally, if the first bypass switch 20 is an electronic switch, the first bypass switch 20 may be a MOS tube, an IGBT, or a triode. In practical applications, including but not limited to these, no specific limitation is made here, and it may be determined according to the specific situation, and all are within the protection scope of this application; for example, Figure 1 MOS tube Q in.

[0070] The first side of the power converter 30 is a DC side, and two poles of the first side of the power converter 30 are connected to two ends of the first bypass switch 20 respectively.

[0071] The first bypass switch 20 and the power converter 30 are controlled by a controller 40 . The controller 40 is used to control the first bypass switch 20 to be disconnected and control the power converter 30 to perform power conversion to its first side when the output voltage of the photovoltaic cluster 100 decreases.

[0072] The power converter 30 performs power conversion to its first side, which means that the power converter 30 takes power from its second side and supplies it to its first side, that is, the voltage on the first side of the power converter 30 is not equal to zero.

[0073] It should be noted that, in actual applications, the controller 40 determines whether the output voltage of the photovoltaic cluster 100 is reduced by detecting the output voltage of the photovoltaic cluster 100 . This technology is very mature in the prior art and will not be described in detail here.

[0074] In one specific example, the second side of the power converter 30 is the DC side, that is, the power converter 30 adopts a DC / DC conversion topology, and the second side of the power converter draws power from a DC power supply; in another specific example, the second side of the power converter 30 is the AC side, that is, the power converter 30 adopts a DC / AC conversion topology, and the second side of the power converter draws power from an AC power supply.

[0075] The above two examples illustrate two implementations of the second side of the power converter 30 , which are not specifically limited here and can be determined according to specific circumstances, and are all within the protection scope of this application.

[0076] Optionally, the power converter 30 may be an isolated converter or a non-isolated converter, which is not specifically limited here and may be determined according to specific circumstances, and is within the protection scope of the present application.

[0077] In a specific example, if Figure 1 As shown, the power converter 30 is an isolation converter, the second side of the power converter 30 is a DC side, and the two poles of the second side of the power converter 30 are respectively connected to the two poles of the output end of the photovoltaic cluster 100 .

[0078] The two poles of the second side of the power converter 30 are respectively connected to the two poles of the output end of the photovoltaic cluster 100 , indicating that the second side of the power converter 30 draws power from the photovoltaic cluster 100 .

[0079] The above example only shows a connection method of the second side of the power converter 30 when the power converter 30 is an isolated converter and the second side of the power converter 30 is a DC side. In practical applications, including but not limited to this, no specific limitation is made here and it may be determined according to the specific situation and is within the protection scope of this application.

[0080] Since the two poles of the first side of the power converter 30 are respectively connected to the two ends of the first bypass switch 20, when the first bypass switch 20 is disconnected, the photovoltaic cluster 100 is connected to the DC side of the DC / AC converter 10 through the first side of the power converter 30; and since the first bypass switch 20 is turned off when the output voltage of the photovoltaic cluster 100 decreases, when the output voltage of the photovoltaic cluster 100 decreases, the photovoltaic cluster 100 is connected to the DC side of the DC / AC converter 10 through the first side of the power converter 30; furthermore, since the power converter 30 performs power conversion to its first side when the output voltage of the photovoltaic cluster 100 decreases, that is, there is a voltage on the first side of the power converter 30, the output voltage of the photovoltaic cluster 100 can be appropriately increased; therefore, the degree of decrease in the output voltage of the photovoltaic cluster 100 can be suppressed, so that the photovoltaic inverter can alleviate the impact of the sudden decrease in the output voltage of the photovoltaic cluster 100 on the power grid.

[0081] It is worth noting that when the output voltage of the photovoltaic cluster 100 decreases, the controller 40 can also control the power converter 30 to perform power conversion according to the degree of decrease in the output voltage of the photovoltaic cluster 100, so that the voltage on the first side of the power converter 30 is almost equal to the decrease value of the output voltage of the photovoltaic cluster 100. Therefore, the photovoltaic inverter can ensure that the DC side voltage of the DC / AC converter 10 remains almost unchanged, thereby achieving seamless switching, that is, there will be almost no impact on the power grid.

[0082] Another embodiment of the present application provides a specific implementation of the power converter 30, where the power converter 30 is an isolated converter and the second side of the power converter 30 is a DC side; the specific structure of this implementation of the power converter 30 can be found in Figure 2 , specifically including: a first boost circuit 31, a first buck circuit 32, a first switch tube M1, a second switch tube M2 and a first anti-reverse circuit 50; the connection relationship between the components is as follows:

[0083] The input end of the first boost circuit 31 serves as the second side of the power converter 30 , the output end of the first boost circuit 31 is connected to the input end of the first buck circuit 32 , and the output end of the first buck circuit 32 serves as the first side of the power converter 30 .

[0084] The first anti-reverse circuit 50 is connected in series in the circuit between the second-side positive electrode of the power converter 30 and the first-side positive electrode of the power converter 30 along the current direction.

[0085] Optionally, the first anti-reverse circuit 50 may be an anti-reverse diode branch. In practical applications, this includes but is not limited to this. No specific limitation is made here and it may be determined according to specific circumstances. All of these are within the protection scope of this application.

[0086] Wherein, the anti-reverse diode branch includes at least one diode; if the number of diodes is greater than 1, all diodes are connected in series in the same direction, and the anode of the series branch formed is used as the anode of the anti-reverse diode branch, and the cathode of the series branch formed is used as the cathode of the anti-reverse diode branch; if the number of diodes is equal to 1, the anode of the diode is used as the anode of the anti-reverse diode branch, and the cathode of the diode is used as the cathode of the anti-reverse diode branch, such as Figure 2 Z1 in.

[0087] If the first boost circuit 31 includes an anti-reverse circuit at the same position as the first anti-reverse circuit 50, and / or the first step-down circuit 32 includes an anti-reverse circuit at the same position as the first anti-reverse circuit 50, then the anti-reverse circuit at the same position as the first anti-reverse circuit 50 in the first boost circuit 31 is integrated with the first anti-reverse circuit 50 into one anti-reverse circuit, or the anti-reverse circuit at the same position as the first anti-reverse circuit 50 in the first step-down circuit 32 is integrated with the first anti-reverse circuit 50 into one anti-reverse circuit.

[0088] The first switch tube M1 is connected in series in a circuit between the negative electrode of the input end of the first boost circuit 31 and the negative electrode of the output end of the first boost circuit 31 .

[0089] Optionally, the first switch tube M1 may be a MOS tube, an IGBT, or a triode. In practical applications, this includes but is not limited to these. No specific limitation is made here and it may be determined according to specific circumstances. All of them are within the protection scope of this application.

[0090] If the first boost circuit 31 includes a switch tube at the same position as the first switch tube M1 , the switch tube at the same position as the first switch tube M1 in the first boost circuit 31 is combined with the first switch tube M1 into one switch tube.

[0091] The second switch tube M2 is connected in series in a circuit between the negative electrode of the input end of the first buck circuit 32 and the negative electrode of the output end of the first buck circuit 32 .

[0092] Optionally, the second switch tube M2 can be a MOS tube, an IGBT, or a triode. In practical applications, this includes but is not limited to these. No specific limitation is made here and it can be determined according to specific circumstances. All of them are within the protection scope of this application.

[0093] If the first buck circuit 32 includes a switch tube at the same position as the second switch tube M2 , the switch tube at the same position as the second switch tube M2 in the first buck circuit 32 and the second switch tube M2 are integrated into one switch tube.

[0094] The first boost circuit 31 , the first buck circuit 32 , the first switch tube M1 , and the second switch tube M2 are all controlled by the controller 40 .

[0095] The working principle of this embodiment of the power converter 30 is as follows:

[0096] Under the control of the controller 40, the working process of the power converter 30 is divided into two stages; in the first stage, the controller 40 controls the first boost circuit 31 to perform power conversion to the output end of the first boost circuit 31, and controls the first buck circuit 32 to stop power conversion; in the second stage, the controller 40 controls the first boost circuit 31 to stop power conversion, and controls the first buck circuit 32 to perform power conversion to the output end of the buck circuit.

[0097] When controlling the first boost circuit 31 to perform power conversion, the controller 40 controls the first switch tube M1 to be turned on or off in a timely manner according to the position of the first switch tube M1 in the first boost circuit 31, so as to cooperate with the power conversion of the first boost circuit 31 and ensure that the first boost circuit 31 can perform power conversion normally; in addition, when controlling the first boost circuit 31 to stop performing power conversion, the controller 40 controls the first switch tube M1 to be turned off.

[0098] When the controller 40 controls the first buck circuit 32 to perform power conversion, the controller 40 controls the second switch tube M2 to be turned on or off in a timely manner according to the position of the second switch tube M2 in the first buck circuit 32 to cooperate with the power conversion of the first buck circuit 32 and ensure that the first buck circuit 32 can perform power conversion normally; in addition, when the controller 40 controls the first buck circuit 32 to stop performing power conversion, the controller 40 controls the second switch tube M2 to be turned off.

[0099] It can be deduced from the above working principle that the first switch tube M1 and the second switch tube M2 will not be turned on at the same time, so the negative electrode on the first side of the power converter 30 is isolated from the negative electrode on the second side of the power converter 30; in addition, due to the reverse cutoff effect of the first anti-reverse circuit 50, the positive electrode on the first side of the power converter 30 is isolated from the positive electrode on the second side of the power converter 30; in summary, this implementation of the power converter 30 can achieve mutual isolation between the first side and the second side of itself.

[0100] This embodiment also provides another specific implementation of the power converter 30, where the power converter 30 is an isolated converter and the second side of the power converter 30 is a DC side; the specific structure of this implementation of the power converter 30 can be found in Figure 3 , specifically including: a second boost circuit 33, a second buck circuit 34, a third switch tube M3, a fourth switch tube M4, a fifth switch tube M5 and a sixth switch tube M6; the connection relationship between the components is as follows:

[0101] The input end of the second boost circuit 33 serves as the second side of the power converter 30 , the output end of the second boost circuit 33 is connected to the input end of the second buck circuit 34 , and the output end of the second buck circuit 34 serves as the first side of the power converter 30 .

[0102] The third switch tube M3 is connected in series in a circuit between the positive electrode of the input end of the second boost circuit 33 and the positive electrode of the output end of the second boost circuit 33 .

[0103] Optionally, the third switch tube M3 can be a MOS tube, an IGBT, or a triode. In practical applications, this includes but is not limited to these. No specific limitation is made here and it can be determined according to specific circumstances. All of them are within the protection scope of this application.

[0104] If the second boost circuit 33 includes a switch tube at the same position as the third switch tube M3 , the switch tube at the same position as the third switch tube M3 in the second boost circuit 33 and the third switch tube M3 are integrated into one switch tube.

[0105] The fourth switch tube M4 is connected in series in a circuit between the negative electrode of the input end of the second boost circuit 33 and the negative electrode of the output end of the second boost circuit 33 .

[0106] Optionally, the fourth switch tube M4 can be a MOS tube, an IGBT, or a triode. In practical applications, this includes but is not limited to these. No specific limitation is made here and it can be determined according to specific circumstances. All of them are within the protection scope of this application.

[0107] If the second boost circuit 33 includes a switch tube at the same position as the fourth switch tube M4 , the switch tube at the same position as the fourth switch tube M4 in the second boost circuit 33 and the fourth switch tube M4 are integrated into one switch tube.

[0108] The fifth switch tube M5 is connected in series in a circuit between the positive electrode of the input end of the second buck circuit 34 and the positive electrode of the output end of the second buck circuit 34 .

[0109] Optionally, the fifth switch tube M5 can be a MOS tube, an IGBT, or a triode. In practical applications, this includes but is not limited to these. No specific limitation is made here and it can be determined according to specific circumstances. All of them are within the protection scope of this application.

[0110] If the second step-down circuit 34 includes a switch tube at the same position as the fifth switch tube M5 , the switch tube at the same position as the fifth switch tube M5 in the second step-down circuit 34 and the fifth switch tube M5 are integrated into one switch tube.

[0111] The sixth switch tube M6 is connected in series in a circuit between the negative electrode of the input end of the second buck circuit 34 and the negative electrode of the output end of the second buck circuit 34 .

[0112] Optionally, the sixth switch tube M6 can be a MOS tube, an IGBT, or a triode. In practical applications, this includes but is not limited to these. No specific limitation is made here and it can be determined according to specific circumstances. All of them are within the protection scope of this application.

[0113] If the second step-down circuit 34 includes a switch tube at the same position as the sixth switch tube M6 , the switch tube at the same position as the sixth switch tube M6 in the second step-down circuit 34 and the sixth switch tube M6 are integrated into one switch tube.

[0114] The working principle of this embodiment of the power converter 30 is as follows:

[0115] Under the control of the controller 40, the working process of the power converter 30 is divided into two stages; in the first stage, the controller 40 controls the second boost circuit 33 to perform power conversion to the output end of the second boost circuit 33, and controls the second buck circuit 34 to stop power conversion; in the second stage, the controller 40 controls the second boost circuit 33 to stop power conversion, and controls the second buck circuit 34 to perform power conversion to the output end of the buck circuit.

[0116] When controlling the second boost circuit 33 to perform power conversion, the controller 40 controls the third switch tube M3 and the fourth switch tube M4 to be turned on or off in a timely manner according to the positions of the third switch tube M3 and the fourth switch tube M4 in the second boost circuit 33, so as to cooperate with the power conversion of the second boost circuit 33 and ensure that the second boost circuit 33 can perform power conversion normally; in addition, when controlling the second boost circuit 33 to stop power conversion, the controller 40 controls the third switch tube M3 and the fourth switch tube M4 to be turned off.

[0117] When the controller 40 controls the second buck circuit 34 to perform power conversion, the controller 40 controls the fifth switch tube M5 and the sixth switch tube M6 to be turned on or off in a timely manner according to the positions of the fifth switch tube M5 and the sixth switch tube M6 in the second buck circuit 34 to cooperate with the power conversion of the second buck circuit 34 and ensure that the second buck circuit 34 can perform power conversion normally; in addition, when the controller 40 controls the second buck circuit 34 to stop performing power conversion, the controller 40 controls the fifth switch tube M5 and the sixth switch tube M6 to be turned off.

[0118] It can be inferred from the above working principle that the third switch tube M3 and the fifth switch tube M5 will not be turned on at the same time, so the negative electrode on the first side of the power converter 30 is isolated from the negative electrode on the second side of the power converter 30; the fourth switch tube M4 and the sixth switch tube M6 will not be turned on at the same time, so the negative electrode on the first side of the power converter 30 is isolated from the negative electrode on the second side of the power converter 30; in summary, this implementation of the power converter 30 can achieve mutual isolation between the first side and the second side of itself.

[0119] The above are only two implementations of the power converter 30. In practical applications, including but not limited to these, for example, the power converter 30 adopts a forward DC / DC conversion topology, which is not specifically limited here and can be determined according to the specific circumstances, all of which are within the scope of protection of this application.

[0120] Since the above two embodiments of the power converter 30 do not use a transformer to achieve isolation, they can save costs, reduce losses, improve efficiency, and also reduce the floor space and improve reliability. Therefore, the above two embodiments of the power converter 30 are preferred embodiments.

[0121] Another embodiment of the present application provides a specific implementation of a boost circuit, and its specific structure can be found in Figure 2 or Figure 3 , which specifically includes: a second inductor branch 01, a second anti-reverse circuit 02, a tenth switch tube M10 and two capacitor branches; the connection between the components is specifically as follows:

[0122] The first end of the second capacitor branch 03 is connected to one end of the second inductor branch 01, and the connection point serves as the positive electrode of the input end of the boost circuit; the other end of the second inductor branch 01 is connected to the input end of the tenth switch tube M10, and the connection point is connected to the anode of the second anti-reverse circuit 02; the output end of the tenth switch tube M10 is connected to the second end of the second capacitor branch 03, and the connection point serves as the negative electrode of the input end of the boost circuit; the cathode of the second anti-reverse circuit 02 is connected to the first end of the third capacitor branch 04, and the connection point serves as the positive electrode of the output end of the boost circuit; the second end of the third capacitor branch 04 is connected to the output end of the tenth switch tube M10, and the connection point serves as the negative electrode of the output end of the boost circuit; the tenth switch tube M10 is controlled by the controller 40.

[0123] The second inductor branch 01 includes at least one inductor; if the number of inductors is greater than 1, all the inductors are connected in series and in parallel, and the two ends of the series branch formed are respectively used as the two ends of the second inductor branch 01; if the number of inductors is equal to 1, the two ends of the inductor are respectively used as the two ends of the second inductor branch 01, for example, Figure 2 or Figure 3 L2 in.

[0124] The second capacitor branch 03 includes at least one capacitor; if the number of capacitors is greater than 1, all capacitors are connected in series and in parallel, and the two ends of the series branch formed are respectively used as the two ends of the second capacitor branch 03; if the number of capacitors is equal to 1, the two ends of the capacitor are respectively used as the two ends of the second capacitor branch 03, for example, Figure 2 or Figure 3 C2 in.

[0125] The third capacitor branch 04 includes at least one capacitor; if the number of capacitors is greater than 1, all capacitors are connected in series and in parallel, and the two ends of the series branch formed are respectively used as the two ends of the third capacitor branch 04; if the number of capacitors is equal to 1, the two ends of the capacitor are respectively used as the two ends of the third capacitor branch 04, for example, Figure 2 or Figure 3 C3 in.

[0126] Optionally, the second anti-reverse circuit 02 may be an anti-reverse diode branch. In practical applications, this includes but is not limited to this. No specific limitation is made here and it may be determined according to specific circumstances. All of these are within the protection scope of this application.

[0127] The anti-reverse diode branch includes at least one diode; if the number of diodes is greater than 1, all diodes are connected in series in the same direction, and the anode of the series branch formed is used as the anode of the anti-reverse diode branch, and the cathode of the series branch formed is used as the cathode of the anti-reverse diode branch; if the number of diodes is equal to 1, the anode of the diode is used as the anode of the anti-reverse diode branch, and the cathode of the diode is used as the cathode of the anti-reverse diode branch, such as Figure 2 or Figure 3Z2 in.

[0128] Optionally, the tenth switch tube M10 can be a MOS tube, an IGBT, or a triode. In practical applications, this includes but is not limited to these. No specific limitation is made here and it can be determined according to specific circumstances. All of them are within the protection scope of this application.

[0129] In a specific example, the boost circuit is a first boost circuit 31, such as Figure 2 As shown, the anode of the first anti-reverse circuit 50 is connected to the cathode of the second anti-reverse circuit 02, and the cathode of the first anti-reverse circuit 50 is connected to the first end of the third capacitor branch 04; the input end of the first switch tube M1 is connected to the second end of the third capacitor branch 04, and the output end of the first switch tube M1 is connected to the output end of the tenth switch tube M10.

[0130] In the first stage, the controller 40 controls the tenth switch tube M10 to be turned on and the first switch tube M1 to be turned off. The second capacitor branch 03 forms a loop through the second inductor branch 01 and the tenth switch tube M10. The second inductor branch 01 is charged and stores energy. The energy flow is as follows: Figure 4 shown.

[0131] In the second stage, the controller 40 controls the tenth switch tube M10 to turn off and the first switch tube M1 to turn on. The second capacitor branch 03 forms a loop through the second inductor branch 01, the second anti-reverse circuit 02, the first anti-reverse circuit 50, the third capacitor branch 04, and the first switch tube M1. The energy on the second inductor branch 01 and the second capacitor branch 03 is transferred to the third capacitor branch 04, and the third capacitor branch 04 is charged and stored. The energy flow is as follows: Figure 5 shown.

[0132] The above is only one configuration method of the first anti-reverse circuit 50 and the first switch tube M1 when the boost circuit is the first boost circuit 31. In practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to the specific situation and is within the protection scope of this application.

[0133] Since the second anti-reverse circuit 02 and the first anti-reverse circuit 50 are located at the same position, the first anti-reverse circuit 50 and the second anti-reverse circuit 02 are integrated into an anti-reverse circuit 11. Figure 6 shown.

[0134] In a specific example, the boost circuit is a second boost circuit 33, such as Figure 3 As shown, the input end of the third switch tube M3 is connected to the cathode of the second anti-reverse circuit 02, and the output end of the third switch tube M3 is connected to the first end of the third capacitor branch 04; the input end of the fourth switch tube M4 is connected to the second end of the third capacitor branch 04, and the output end of the fourth switch tube M4 is connected to the output end of the tenth switch tube M10.

[0135] In the first stage, the controller 40 controls the tenth switch tube M10 to be turned on, the third switch tube M3 to be turned off, and the fourth switch tube M4 to be turned off. The second capacitor branch 03 forms a loop through the second inductor branch 01 and the tenth switch tube M10. The second inductor branch 01 is charged and stores energy. The energy flow is as follows: Figure 7 shown.

[0136] In the second stage, the controller 40 controls the tenth switch tube M10 to turn off, the third switch tube M3 to turn on, and the fourth switch tube M4 to turn on. The second capacitor branch 03 forms a loop through the second inductor branch 01, the second anti-reverse circuit 02, the third switch tube M3, the third capacitor branch 04, and the fourth switch tube M4. The energy on the second inductor branch 01 and the second capacitor branch 03 is transferred to the third capacitor branch 04, and the third capacitor branch 04 is charged and stores energy. The energy flow is as follows: Figure 8 shown.

[0137] The above is only one configuration method of the third switch tube M3 and the fourth switch tube M4 when the boost circuit is the second boost circuit 33. In practical applications, including but not limited to this, no specific limitation is made here and it can be determined according to the specific situation and is within the protection scope of this application.

[0138] The above is only one implementation of the boost circuit. In practical applications, including but not limited to this, no specific limitation is made here and it may be determined according to the specific circumstances, all of which are within the protection scope of this application.

[0139] Another embodiment of the present application provides a specific implementation of a step-down circuit, and its specific structure can be found in Figure 2 or Figure 3 , which specifically includes: a first inductor branch 05, a first capacitor branch 06 and a seventh switch tube M7; the connection relationship between the components is specifically as follows:

[0140] The first end of the first inductor branch 05 serves as the positive electrode of the input end of the step-down circuit; the second end of the first inductor branch 05 is connected to the first end of the first capacitor branch 06, and the connection point serves as the positive electrode of the output end of the step-down circuit; the second end of the first capacitor branch 06 is connected to the input end of the seventh switch tube M7, and the connection point serves as the negative electrode of the output end of the step-down circuit; the output end of the seventh switch tube M7 serves as the negative electrode of the input end of the step-down circuit; the seventh switch tube M7 is controlled by the controller 40.

[0141] The first inductor branch 05 includes at least one inductor; if the number of inductors is greater than 1, all the inductors are connected in series and in parallel, and the two ends of the series branch formed are respectively used as the two ends of the first inductor branch 05; if the number of inductors is equal to 1, the two ends of the inductor are respectively used as the two ends of the first inductor branch 05, for example, Figure 2 or Figure 3 L1 in.

[0142] The first capacitor branch 06 includes at least one capacitor; if the number of capacitors is greater than 1, all capacitors are connected in series and in parallel, and the two ends of the series branch formed are respectively used as the two ends of the first capacitor branch 06; if the number of capacitors is equal to 1, the two ends of the capacitor are respectively used as the two ends of the first capacitor branch 06, for example, Figure 2 or Figure 3 C1 in.

[0143] Optionally, the seventh switch tube M7 can be a MOS tube, an IGBT, or a triode. In practical applications, this includes but is not limited to these. No specific limitation is made here and it can be determined according to specific circumstances. All of them are within the protection scope of this application.

[0144] In a specific example, the step-down circuit is a first step-down circuit 32, such as Figure 2 As shown, the input end of the second switch tube M2 is connected to the output end of the seventh switch tube M7 , and the output end of the second switch tube M2 serves as the negative electrode of the input end of the first buck circuit 32 .

[0145] The controller 40 controls the seventh switch tube M7 and the second switch tube M2 to be turned on, and the third capacitor branch 04 forms a loop through the first inductor branch 05, the first capacitor branch 06, the seventh switch tube M7, and the second switch tube M2. The energy on the third capacitor branch 04 is transferred to the first capacitor branch 06, and the first capacitor branch 06 is charged and stored. The energy flow is as follows: Fig. 9 shown.

[0146] The above is only one configuration method of the second switch tube M2 when the buck circuit is the first buck circuit 32. In practical applications, it includes but is not limited to this. No specific limitation is made here and it can be determined according to the specific situation. All of them are within the protection scope of this application.

[0147] Since the seventh switch tube M7 and the second switch tube M2 are in the same position, the seventh switch tube M7 and the second switch tube M2 are integrated into a switch tube M11. Fig.10 ( Fig.10 exist Figure 6 ) as shown.

[0148] In a specific example, the step-down circuit is a second step-down circuit 34, such as Figure 3 As shown, the input end of the fifth switch tube M5 is connected to the positive electrode of the input end of the second buck circuit 34, and the output end of the fifth switch tube M5 is connected to the first end of the first inductor branch 05; the input end of the sixth switch tube M6 is connected to the output end of the seventh switch tube M7, and the output end of the sixth switch tube M6 is connected to the negative electrode of the input end of the second buck circuit 34.

[0149] The controller 40 controls the fifth switch tube M5, the sixth switch tube M6, and the seventh switch tube M7 to be turned on. The third capacitor branch 04 forms a loop through the fifth switch tube M5, the first inductor branch 05, the first capacitor branch 06, the seventh switch tube M7, and the sixth switch tube M6. The energy on the third capacitor branch 04 is transferred to the first capacitor branch 06, and the first capacitor branch 06 is charged and stored. The energy flow is as follows: Fig.11 shown.

[0150] The above is only one configuration method of the fifth switch tube M5 and the sixth switch tube M6 when the buck circuit is the second buck circuit 34. In practical applications, it includes but is not limited to this. No specific limitation is made here and it can be determined according to the specific situation. It is all within the protection scope of this application.

[0151] Since the seventh switch tube M7 and the sixth switch tube M6 are in the same position, the seventh switch tube M7 and the sixth switch tube M6 are integrated into a switch tube M12. Fig.12 shown.

[0152] The above is only one implementation of the step-down circuit. In practical applications, including but not limited to this, no specific limitation is made here and it may be determined according to the specific circumstances, all of which are within the protection scope of this application.

[0153] Another embodiment of the present application provides another implementation of a photovoltaic inverter. The specific structure of this implementation can be found in Fig.13 (Only in Figure 1 This embodiment is based on the above embodiment and further includes: two switches.

[0154] The positive electrode of the second side of the power converter 30 is connected to one end of the first switch S1, and the negative electrode of the second side of the power converter 30 is connected to one end of the second switch S2; the first switch S1 and the second switch S2 are both controlled by the controller 40 (in order to simplify the view, Fig.13 The connection between the two switches and the controller 40 is not shown).

[0155] The controller 40 is used to control the first switch S1 and the second switch S2 to close before controlling the power converter 30 to perform power conversion to the first side thereof.

[0156] In one specific example, the controller 40 is used to control the first switch S1 and the second switch S2 to be closed when the first bypass switch 20 is controlled to be closed; in another specific example, the controller 40 is used to control the first switch S1 and the second switch S2 to be closed when the first bypass switch 20 is controlled to be opened.

[0157] Since a capacitor is usually provided between the two poles on the second side of the power converter 30, in the control method of the controller 40 for the first switch S1 and the second switch S2 shown in the first example, the capacitor can be fully charged in advance, so that the first side of the power converter 30 obtains the voltage faster, and thus the control method of the controller 40 for the first switch S1 and the second switch S2 shown in the first example is selected as the preferred implementation method.

[0158] The above two examples only show two control methods of the controller 40 for the first switch S1 and the second switch S2. In practical applications, including but not limited to these, no specific limitation is made here and it may be determined according to the specific situation, all of which are within the protection scope of this application.

[0159] Another embodiment of the present application provides another implementation of a photovoltaic inverter. The specific structure of this implementation can be found in Fig.14 ( Fig.14 Only in Fig.13 This embodiment is based on the above embodiment and further includes: a second bypass switch 60.

[0160] The second bypass switch 60 is connected in parallel with the first bypass switch 20; the second bypass switch 60 is controlled by the controller 40, and the controller 40 is used to control the second bypass switch 60 to close when the first bypass switch 20 cannot be closed normally;

[0161] Optionally, the second bypass switch 60 may be an electronic switch or a mechanical switch. In practical applications, this includes but is not limited to these. No specific limitation is made here and it may be determined according to specific circumstances. All of these are within the scope of protection of this application.

[0162] Optionally, if the second bypass switch 60 is a mechanical switch, the second bypass switch 60 may be a relay. In practical applications, including but not limited to this, no specific limitation is made here and it may be determined according to the specific circumstances and is within the protection scope of this application.

[0163] In this embodiment, the second bypass switch 60 can be closed when the first bypass switch 20 cannot be closed normally, thereby reducing the possibility that the photovoltaic cluster 100 cannot output externally, thereby improving the reliability of the photovoltaic cluster 100 output externally to a certain extent.

[0164] Another embodiment of the present application provides a photovoltaic power generation system, the specific structure of which can be seen in Fig.15 , specifically comprising: a photovoltaic cluster 100 and a photovoltaic inverter 200 as provided in the above embodiment.

[0165] It should be noted that the connection relationship between the photovoltaic inverter 200 and the photovoltaic cluster 100 has been described in detail in the above embodiment and will not be repeated here.

[0166] This embodiment also provides a specific implementation of the photovoltaic cluster 100. The specific structure of the photovoltaic cluster 100 can be found in Fig.15 , specifically including: at least two component modules 110 connected in series; the component module 110 includes: a photovoltaic component 111, an eighth switch tube M8 and a ninth switch tube M9.

[0167] In the assembly module 110 , the photovoltaic assembly 111 is connected in series with the eighth switch tube M8 , and the formed series branch is connected in parallel with the ninth switch tube M9 , and both ends of the formed parallel branch serve as the two ends of the assembly module 110 .

[0168] Optionally, the eighth switch tube M8 can be a MOS tube, an IGBT, or a triode. In practical applications, this includes but is not limited to these. No specific limitation is made here and it may be determined according to the specific circumstances. All are within the protection scope of this application.

[0169] Optionally, the ninth switch tube M9 can be a MOS tube, an IGBT, or a triode. In practical applications, this includes but is not limited to these. No specific limitation is made here and it may depend on the specific situation. All of them are within the protection scope of this application.

[0170] The eighth switch tube M8 and the ninth switch tube M9 are both controlled by the controller 40 in the photovoltaic inverter 200. The controller 40 is used to control the eighth switch tube M8 to be turned off and the ninth switch tube M9 to be turned on when the voltage across the component module 110 is less than a preset voltage.

[0171] The fact that the voltage across the component module 110 is less than the preset voltage indicates that the voltage across the component module 110 is relatively small. In practical applications, the preset voltage is set according to actual conditions and is not specifically limited here.

[0172] It should be noted that when the intensity of light irradiating the photovoltaic component 111 is weak, or when a failure occurs in the photovoltaic component 111 , the voltage across the component module 110 is less than a preset voltage.

[0173] For example, assuming that there are N component modules 110, under normal circumstances, the N eighth switch tubes M8 are all turned on, and the N ninth switch tubes M9 are all turned off. At this time, the output voltage of the photovoltaic cluster 100 is equal to the sum of the output voltages of the N photovoltaic components 111; when the photovoltaic component 111 in the second component module 110 from the top fails or the intensity of light received is weak, the eighth switch tube M8 in the component module 110 is turned off and the ninth switch tube M9 is turned on, so that the photovoltaic component 111 of the component module 110 is cut out from the photovoltaic cluster 100. At this time, the output voltage of the photovoltaic cluster 100 is equal to the sum of the output voltages of N-1 photovoltaic components 111.

[0174] Since in the component module 110, the eighth switch tube M8 is connected in series with the photovoltaic component 111, and the ninth switch tube M9 is connected in parallel at both ends of the series branch formed by the photovoltaic component 111 and the eighth switch tube M8, after the eighth switch tube M8 is turned off and the ninth switch tube M9 is turned on, the photovoltaic component 111 is cut out, and the series branch formed by the photovoltaic component 111 and the eighth switch tube M8 is replaced by the ninth switch tube M9 to be connected to other component modules 110, so as to ensure that the photovoltaic cluster 100 can still output to the outside.

[0175] For the above description of the disclosed embodiments, the features recorded in each embodiment in this specification can be replaced or combined with each other, so that professionals in the field can implement or use the present application. The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with a preferred embodiment, it is not used to limit the present invention. Any technician familiar with the field can make many possible changes and modifications to the technical solution of the present invention using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A photovoltaic inverter, characterized in that: include: A DC / AC converter, a first bypass switch, a power converter and a controller; wherein: The first end of the first bypass switch is connected in series with the photovoltaic cluster, and the two poles of the series branch formed are respectively connected to the two poles of the DC side of the DC / AC converter; the controller is connected to the control end of the first bypass switch; The first side of the power converter is a DC side, and the two poles of the first side of the power converter are respectively connected to the first end and the second end of the first bypass switch; the two poles of the second side of the power converter are respectively connected to the two poles of the output end of the photovoltaic cluster; The first bypass switch and the power converter are controlled by the controller, and the controller is used to control the first bypass switch to be disconnected and control the power converter to perform power conversion to its first side when the output voltage of the photovoltaic cluster decreases.

2. The photovoltaic inverter according to claim 1, characterized in that: The power converter is an isolated converter; the second side of the power converter is a DC side.

3. The photovoltaic inverter according to claim 1, characterized in that: The power converter is an isolated converter, the second side of the power converter is a DC side, and the power converter includes: a first boost circuit, a first buck circuit, a first switch tube, a second switch tube and a first anti-reverse circuit; wherein: The input end of the first boost circuit serves as the second side of the power converter, the output end of the first boost circuit is connected to the input end of the first buck circuit, and the output end of the first buck circuit serves as the first side of the power converter; The first anti-reverse circuit is connected in series in the circuit between the second side positive electrode of the power converter and the first side positive electrode of the power converter along the current direction; The first switch tube is connected in series in a circuit between the negative electrode of the input end of the first boost circuit and the negative electrode of the output end of the first boost circuit; The second switch tube is connected in series in a circuit between the negative electrode of the input end of the first buck circuit and the negative electrode of the output end of the first buck circuit; The first boost circuit, the first buck circuit, the first switch tube and the second switch tube are all controlled by the controller.

4. The photovoltaic inverter according to claim 3, characterized in that: The anti-reverse circuit in the first boost circuit, which is located at the same position as the first anti-reverse circuit, is integrated with the first anti-reverse circuit into an anti-reverse circuit; or, The anti-reverse circuit in the first step-down circuit and the first anti-reverse circuit located at the same position as the first anti-reverse circuit are integrated with the first anti-reverse circuit into one anti-reverse circuit.

5. The photovoltaic inverter according to claim 3, characterized in that: The switch tube in the first boost circuit that is located at the same position as the first switch tube is integrated with the first switch tube into one switch tube; The switch tube in the first step-down circuit that is located at the same position as the second switch tube is integrated with the second switch tube into one switch tube.

6. The photovoltaic inverter according to claim 1, characterized in that: The power converter is an isolated converter, the second side of the power converter is a DC side, and the power converter includes: a second boost circuit, a second buck circuit, a third switch tube, a fourth switch tube, a fifth switch tube and a sixth switch tube; wherein: The input end of the second boost circuit serves as the second side of the power converter, the output end of the second boost circuit is connected to the input end of the second buck circuit, and the output end of the second buck circuit serves as the first side of the power converter; The third switch tube is connected in series in a circuit between the positive electrode of the input end of the second boost circuit and the positive electrode of the output end of the second boost circuit; The fourth switch tube is connected in series in a circuit between the negative electrode of the input end of the second boost circuit and the negative electrode of the output end of the second boost circuit; The fifth switch tube is connected in series in a circuit between the positive electrode of the input end of the second buck circuit and the positive electrode of the output end of the second buck circuit; The sixth switch tube is connected in series in a circuit between the negative electrode of the input end of the second buck circuit and the negative electrode of the output end of the second buck circuit.

7. The photovoltaic inverter according to claim 6, characterized in that: The switch tube in the second boost circuit that is located at the same position as the third switch tube is integrated with the third switch tube into one switch tube; The switch tube in the second boost circuit that is located at the same position as the fourth switch tube is integrated with the fourth switch tube into one switch tube; The switch tube in the second step-down circuit that is located at the same position as the fifth switch tube is integrated with the fifth switch tube into one switch tube; The switch tube in the second step-down circuit that is located at the same position as the sixth switch tube is integrated with the sixth switch tube into one switch tube.

8. The photovoltaic inverter according to any one of claims 3 to 7, characterized in that: The voltage boost circuit is a Boost circuit.

9. The photovoltaic inverter according to any one of claims 3 to 5, characterized in that: The first step-down circuit includes: a first inductor branch, a first capacitor branch and a seventh switch tube; wherein: The first end of the first inductor branch serves as the positive electrode of the input end of the first buck circuit; The second end of the first inductor branch is connected to the first end of the first capacitor branch, and the connection point serves as the positive electrode of the output end of the first buck circuit; The second end of the first capacitor branch is connected to the input end of the seventh switch tube, and the connection point serves as the negative electrode of the output end of the first buck circuit; The output end of the seventh switch tube serves as the negative electrode of the input end of the first buck circuit; The seventh switch tube is controlled by the controller.

10. The photovoltaic inverter according to any one of claims 1 to 7, characterized in that: Also includes: Two switches; of which: The positive electrode of the second side of the power converter is connected to one end of the first switch, and the negative electrode of the second side of the power converter is connected to one end of the second switch; the other end of the first switch is connected to the negative electrode of the first side of the power converter; the other end of the second switch is connected to the DC / AC converter; The first switch and the second switch are both controlled by the controller, and the controller is used to control the first switch and the second switch to close before controlling the power converter to perform power conversion to the first side of the power converter.

11. The photovoltaic inverter according to any one of claims 1 to 7, characterized in that: The photovoltaic inverter further includes: a second bypass switch; wherein: The second bypass switch is connected in parallel with the first bypass switch; The second bypass switch is controlled by the controller, and the controller is used to control the second bypass switch to close when the first bypass switch cannot be closed normally.

12. A photovoltaic power generation system, characterized in that: include: A photovoltaic cluster and a photovoltaic inverter as claimed in any one of claims 1 to 11.

13. The photovoltaic power generation system according to claim 12, characterized in that: The photovoltaic cluster comprises: at least two component modules connected in series; the component module comprises: a photovoltaic component, an eighth switch tube and a ninth switch tube; In the component module, the photovoltaic component is connected in series with the eighth switch tube, the formed series branch is connected in parallel with the ninth switch tube, and the two ends of the formed parallel branch serve as the two ends of the component module respectively; The eighth switch tube and the ninth switch tube are both controlled by a controller in the photovoltaic inverter, and the controller is used to control the eighth switch tube to turn off and the ninth switch tube to turn on when the voltage across the component module is less than a preset voltage.

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