CN221042318U - Photovoltaic inversion device - Google Patents

Abstract

The utility model discloses a photovoltaic inverter. The device comprises: the photovoltaic module is used for converting light energy into electric energy; at least three bridge arms connected in parallel with each other; the bridge arm comprises a short-circuit protection unit; the first end of the bridge arm is connected with the first end of the photovoltaic module; the second end of the bridge arm is connected with the second end of the photovoltaic module; the midpoint end of the bridge arm is connected with the third end of the photovoltaic module; the short-circuit protection unit is correspondingly and electrically connected with the bridge arm, and the bridge arm is used for converting direct current output by the photovoltaic module into alternating current; the short-circuit protection unit is used for preventing the photovoltaic module from being short-circuited to the ground through a load. According to the embodiment of the utility model, the short-circuit protection unit is arranged in the bridge arm, and is turned off when the photovoltaic inverter is subjected to wave-sealing protection, so that a ground short-circuit loop between the photovoltaic module and the load is cut off, and the inverter circuit is prevented from losing effectiveness due to ground short-circuit.

Description

Photovoltaic inversion device

Technical Field

The utility model relates to the technical field of photovoltaic inversion, in particular to a photovoltaic inversion device.

Background

The current industry inverter basically has a function of detecting the PV-to-ground insulation resistance, but the function can only detect the PV-to-ground insulation resistance value before the inverter is connected with the grid for a plurality of reasons, and then the PV-to-ground insulation resistance value is judged to be protected.

However, in an actual photovoltaic power station, due to construction, cable aging and other reasons, there is a short circuit to the ground in the running state of the inverter, as shown in fig. 1, a short circuit failure loop is a PV cable, an anti-parallel diode of an IGBT of a lower half bridge of the inverter module, a relay, a power grid and the ground, and even if an overcurrent can be detected by a current sensor on the inversion side, the anti-parallel diode of the IGBT belongs to an uncontrollable device, and the short circuit failure loop cannot be cut off, so that the photovoltaic inverter device has the risk of short circuit failure to the ground of the inverter.

Disclosure of utility model

The utility model provides a photovoltaic inverter device, which is used for preventing an inverter circuit from failing due to a ground short circuit.

According to an aspect of the present utility model, there is provided a photovoltaic inverter apparatus including:

the photovoltaic module is used for converting light energy into electric energy;

At least three bridge arms connected in parallel with each other; the bridge arm comprises a short-circuit protection unit; the first end of the bridge arm is connected with the first end of the photovoltaic module; the second end of the bridge arm is connected with the second end of the photovoltaic module; the midpoint end of the bridge arm is connected with the third end of the photovoltaic module; the short-circuit protection unit is correspondingly and electrically connected with the bridge arm, and the bridge arm is used for converting direct current output by the photovoltaic module into alternating current; the short-circuit protection unit is used for preventing the photovoltaic module from being short-circuited to the ground through a load.

Optionally, the bridge arms are all of T-shaped inversion structures; the T-shaped bridge arm comprises: the first bridge arm, the second bridge arm and the third bridge arm;

The first end of the first bridge arm is used as a midpoint end of the bridge arm; the first end of the second bridge arm is used as the first end of the bridge arm; the second end of the second bridge arm is connected with the second end of the first bridge arm; the first end of the third bridge arm is connected with the second end of the second bridge arm; and the second end of the third bridge arm is used as the second end of the bridge arm.

Optionally, the bridge arms are all I-shaped bridge arms.

Optionally, the first bridge arm includes: a first switching tube and a second switching tube; the second bridge arm includes: a third switching tube; the third leg includes: a fourth switching tube and a short-circuit protection unit;

the input end of the first switching tube is used as a first end of the first bridge arm; the output end of the first switching tube is connected with the output end of the second switching tube; the input end of the second switching tube is used as a second end of the first bridge arm; the input end of the third switching tube is used as the first end of the second bridge arm; the output end of the third switching tube is used as a second end of the second bridge arm; the input end of the fourth switching tube is used as the first end of the third bridge arm; the output end of the fourth switching tube is connected with the first end of the short-circuit protection unit; and the second end of the short-circuit protection unit is used as the second end of the third bridge arm.

Optionally, the first bridge arm includes: a fifth switching tube and a sixth switching tube; the second bridge arm includes: a seventh switching tube; the third leg includes: an eighth switching tube and a short-circuit protection unit;

The input end of the fifth switching tube is used as a first end of the first bridge arm; the output end of the fifth switching tube is connected with the output end of the sixth switching tube; the input end of the sixth switching tube is used as the second end of the first bridge arm; the input end of the seventh switching tube is used as the first end of the second bridge arm; the output end of the seventh switching tube is used as a second end of the second bridge arm; the input end of the eighth switching tube is used as the first end of the third bridge arm; the output end of the eighth switching tube is used as the second end of the third bridge arm; the short-circuit protection unit is connected in parallel with the eighth switching tube.

Optionally, the bridge arm includes: a first diode, a second diode, a ninth switching tube, a tenth switching tube, an eleventh switching tube, a twelfth switching tube and a short-circuit protection unit;

The input end of the ninth switching tube is connected with the first end of the photovoltaic module; the output end of the ninth switching tube is connected with the input end of the tenth switching tube; the output end of the tenth switching tube is connected with the input end of the eleventh switching tube; the output end of the eleventh switching tube is connected with the input end of the twelfth switching tube; the output end of the twelfth switching tube is connected with the first end of the short-circuit protection unit; the second end of the short-circuit protection unit is connected with the second end of the photovoltaic module; the anode end of the first diode is used as the midpoint end of the bridge arm; the cathode end of the first diode is connected with the output end of the ninth switching tube; the anode end of the second diode is connected with the anode end of the first diode; and the cathode end of the second diode is connected with the output end of the eleventh switching tube.

Optionally, the bridge arm includes: a third diode, a fourth diode, a thirteenth switching tube, a fourteenth switching tube, a fifteenth switching tube, a sixteenth switching tube and a short-circuit protection unit;

The input end of the thirteenth switching tube is connected with the first end of the photovoltaic module; the output end of the thirteenth switching tube is connected with the input end of the fourteenth switching tube; the output end of the fourteenth switching tube is connected with the input end of the fifteenth switching tube; the output end of the fifteenth switching tube is connected with the input end of the sixteenth switching tube; the output end of the sixteenth switching tube is connected with the second end of the photovoltaic module; the short-circuit protection unit is connected with the sixteenth switching tube in parallel; the anode end of the third diode is used as the midpoint end of the bridge arm; the cathode end of the third diode is connected with the output end of the thirteenth switching tube; the anode end of the fourth diode is connected with the anode end of the third diode; and the cathode end of the fourth diode is connected with the output end of the fifteenth switching tube.

Optionally, the short-circuit protection unit is a switching tube.

Optionally, the photovoltaic module includes: the photovoltaic device comprises a photovoltaic unit, an anti-backflow diode, an inductive energy storage unit and a capacitive energy storage unit;

The first end of the inductance energy storage unit is connected with the first end of the photovoltaic unit; the second end of the inductance energy storage unit is connected with the anode end of the anti-backflow diode; the third end of the inductance energy storage unit is connected with the second end of the photovoltaic unit; the cathode end of the anti-reflux diode is used as a first end of the photovoltaic module; the first end of the capacitor energy storage unit is connected with the cathode end of the anti-countercurrent diode; the second end of the capacitive energy storage unit is used as the second end of the photovoltaic module; and the third end of the capacitive energy storage unit is used as the third end of the photovoltaic module.

Optionally, the inductive energy storage unit includes: the first inductor and the energy storage switch tube;

the first end of the first inductor is connected with the first end of the photovoltaic unit; the second end of the first inductor is connected with the input end of the energy storage switch tube; and the output end of the energy storage switch tube is connected with the second end of the photovoltaic unit.

The capacitive energy storage unit includes: a first capacitor and a second capacitor;

The first end of the first capacitor is used as the first end of the capacitor energy storage unit; the second end of the first capacitor is used as a third end of the capacitor energy storage unit; the first end of the second capacitor is connected with the second end of the first capacitor; the second end of the second capacitor is used as the second end of the capacitor energy storage unit.

In the embodiment of the utility model, the short-circuit protection unit is arranged in the bridge arm. The short-circuit protection unit is in a conducting state when the bridge arm works normally, and is in a cutting-off state when the bridge arm is protected by wave sealing. At this time, the short circuit to ground between the photovoltaic module and the load is disconnected, thereby preventing the photovoltaic module from being shorted to ground through the load. According to the embodiment of the utility model, the short-circuit protection unit is arranged in the bridge arm, and is turned off when the photovoltaic inverter is subjected to wave-sealing protection, so that a ground short-circuit loop between the photovoltaic module and the load is cut off, and the inverter circuit is prevented from losing effectiveness due to ground short-circuit.

It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the utility model or to delineate the scope of the utility model. Other features of the present utility model will become apparent from the description that follows.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present utility model, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic diagram of an inverter short-circuit failure circuit.

Fig. 2 is a schematic diagram of a photovoltaic inverter provided in an embodiment of the present utility model;

Fig. 3 is a schematic diagram of another photovoltaic inverter provided in an embodiment of the present utility model;

fig. 4 is a schematic diagram of another photovoltaic inverter provided in an embodiment of the present utility model;

fig. 5 is a schematic diagram of another photovoltaic inverter according to an embodiment of the present utility model.

Detailed Description

In order that those skilled in the art will better understand the present utility model, a technical solution in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present utility model without making any inventive effort, shall fall within the scope of the present utility model.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present utility model and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the utility model described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The embodiment of the utility model provides a photovoltaic inverter. The device can be applied to photovoltaic inversion scenes. Fig. 2 is a schematic diagram of a photovoltaic inverter according to an embodiment of the present utility model. Referring to fig. 2, the apparatus includes: the photovoltaic module and at least three bridge arms connected in parallel with each other.

The photovoltaic module 110 is used for converting light energy into electric energy; bridge arm 120 includes a short circuit protection unit 130; a first end of bridge arm 120 is connected to a first end of photovoltaic module 110; a second end of the bridge arm 120 is connected to a second end of the photovoltaic module 110; the midpoint end of the bridge arm 120 is connected with the third end of the photovoltaic module 110; the short-circuit protection unit 130 is correspondingly and electrically connected with the bridge arm 120, and the bridge arm 120 is used for converting direct current output by the photovoltaic module 110 into alternating current; the short protection unit 130 is used to prevent the photovoltaic module 110 from being shorted to ground through a load.

Specifically, the plurality of bridge arms 120 are connected in parallel to each other to form an inverter circuit, so that the direct current output by the photovoltaic module 110 is converted into alternating current. The short-circuit protection unit 130 maintains a conductive state when the bridge arm 120 is operating normally. At this time, the bridge arm 120 converts the dc power at the output end of the photovoltaic module 110 into ac power, and sends the ac power to the load. When the bridge arm 120 is protected by the sealing wave, the short-circuit protection unit 130 is turned off. At this point the connection between the bridge arm 120 and the second end of the photovoltaic module 110 is broken. In other words, when the short protection unit 130 is turned off, the short circuit to ground of the photovoltaic module is opened. At this time, the current of the photovoltaic module 110 cannot enter the load through the bridge arm 120. The load may be a power grid, and the load may be various in kind during practical application, and the photovoltaic inverter provided in this embodiment may be applied to various types of inverter scenarios.

In the embodiment of the present utility model, the short-circuit protection unit 130 is disposed in the bridge arm 120. The short-circuit protection unit 130 is in a conducting state when the bridge arm 120 works normally, and the short-circuit protection unit 130 is in an off state when the bridge arm 120 is in the wave-sealing protection. At this time, the short circuit to ground between the photovoltaic module 110 and the load is disconnected, thereby preventing the photovoltaic module 110 from being shorted to ground by the load. In the embodiment of the utility model, the short-circuit protection unit 130 is arranged in the bridge arm 120, and the short-circuit protection unit 120 is turned off when the photovoltaic inverter is subjected to wave-sealing protection, so that a ground short-circuit loop between the photovoltaic module 110 and a load is cut off, and the inverter circuit is prevented from losing efficacy due to ground short-circuit.

On the basis of the above embodiments, the short-circuit protection unit 130 is optionally a switching tube.

It should be noted that, the short-circuit protection unit 130 has different setting modes in different types of circuit structures, and the setting modes of the short-circuit protection unit 130 may be selected according to the actual circuit types in practical application, which is not limited in this embodiment.

Optionally, with continued reference to fig. 2, the bridge arms 120 are all T-shaped inverter structures; the T-shaped bridge arm comprises: first leg 121, second leg 122, and third leg 123;

A first end of the first bridge arm 121 serves as a midpoint end of the bridge arm 120; a first end of second leg 122 serves as a first end of leg 120; a second end of the second bridge arm 122 is connected to a second end of the first bridge arm 121; a first end of the third leg 123 is connected to a second end of the second leg 122; a second end of third leg 123 serves as a second end of leg 120.

Optionally, with continued reference to fig. 2, based on the foregoing embodiment, the first bridge arm 121 includes: a first switching tube Q1 and a second switching tube Q2; the second leg 122 includes: a third switching tube Q3; the third leg 123 includes: a fourth switching tube Q4 and a short-circuit protection unit 130.

The input end of the first switching tube Q1 is used as a first end of the first bridge arm 121; the output end of the first switching tube Q1 is connected with the output end of the second switching tube Q2; the input end of the second switching tube Q2 is used as the second end of the first bridge arm 121; the input end of the third switching tube Q3 is used as the first end of the second bridge arm 122; the output end of the third switching tube Q3 is used as the second end of the second bridge arm 122; the input end of the fourth switching tube Q4 is used as the first end of the third bridge arm 123; the output end of the fourth switching tube Q4 is connected with the first end of the short-circuit protection unit 130; a second end of the short-circuit protection unit 130 serves as a second end of the third leg 123.

Specifically, when the photovoltaic inverter is protected by the wave-sealing protection, the short-circuit protection unit 130 is turned off, and at this time, the third bridge arm 123 of the bridge arm 120 is open, so that the current in the photovoltaic module 110 cannot enter the load through the third bridge arm 123. It should be noted that, in this arrangement, the short-circuit protection unit 130 should be disposed opposite to the fourth switching tube Q4, that is, in this arrangement, the output end of the short-circuit protection unit 130 is connected to the output end of the fourth switching tube Q4, and the input end of the short-circuit protection unit 130 is connected to the second end of the photovoltaic module 110.

Fig. 3 is a schematic diagram of another photovoltaic inverter according to an embodiment of the present utility model. Optionally, referring to fig. 3, on the basis of the above embodiments, the first bridge arm 121 includes: a fifth switching tube Q5 and a sixth switching tube Q6; the second leg 122 includes: a seventh switching tube Q7; the third leg 123 includes: an eighth switching tube Q8 and a short-circuit protection unit 130.

The input end of the fifth switching tube Q5 is used as the first end of the first bridge arm 121; the output end of the fifth switching tube Q5 is connected with the output end of the sixth switching tube Q6; the input end of the sixth switching tube Q6 is used as the second end of the first bridge arm 121; the input end of the seventh switching tube Q7 is used as the first end of the second bridge arm 122; the output end of the seventh switching tube Q7 is used as the second end of the second bridge arm 122; the input end of the eighth switching tube Q8 is used as the first end of the third bridge arm 123; the output end of the eighth switching tube Q8 is used as the second end of the third bridge arm 123; the short protection unit 130 is connected in parallel with the eighth switching tube Q8.

Specifically, when the photovoltaic inverter is protected by the wave-sealing protection, the short-circuit protection unit 130 is turned off, and at this time, the third bridge arm 123 of the bridge arm 120 is open, so that the current in the photovoltaic module 110 cannot enter the load through the third bridge arm 123. In this arrangement, the input terminal of the short-circuit protection unit 130 is connected to the input terminal of the eighth switching tube Q8, and the output terminal of the short-circuit protection unit 130 is connected to the output terminal of the eighth switching tube Q8. The short protection unit 130 and the eighth switching tube Q8 need to be driven separately.

Based on the above embodiments, the bridge arms 120 are optionally I-type bridge arms.

Fig. 4 is a schematic diagram of another photovoltaic inverter according to an embodiment of the present utility model. Optionally, referring to fig. 4, on the basis of the above embodiments, the bridge arm 120 includes: a first diode D1, a second diode D2, a ninth switching tube Q9, a tenth switching tube Q10, an eleventh switching tube Q11, a twelfth switching tube Q12, and a short-circuit protection unit 130.

An input end of the ninth switching tube Q9 is connected with a first end of the photovoltaic module 110; the output end of the ninth switching tube Q9 is connected with the input end of the tenth switching tube Q10; the output end of the tenth switching tube Q10 is connected with the input end of the eleventh switching tube Q11; the output end of the eleventh switching tube Q11 is connected with the input end of the twelfth switching tube Q12; the output end of the twelfth switching tube Q12 is connected with the first end of the short-circuit protection unit 130; a second end of the short protection unit 130 is connected to a second end of the photovoltaic module 110; the anode terminal of the first diode D1 is taken as the midpoint terminal of the bridge arm 120; the cathode end of the first diode D1 is connected with the output end of the ninth switching tube Q9; the anode end of the second diode D2 is connected with the anode end of the first diode D1; the cathode terminal of the second diode D2 is connected to the output terminal of the eleventh switching transistor Q11.

Specifically, the photovoltaic inverter shown in fig. 4 is different from the photovoltaic inverter shown in fig. 2 only in the arrangement structure of the bridge arm 120, and the rest is the same, and the description thereof is omitted here.

Fig. 5 is a schematic diagram of another photovoltaic inverter according to an embodiment of the present utility model. Optionally, referring to fig. 5, on the basis of the above embodiments, the bridge arm includes: a third diode D3, a fourth diode D4, a thirteenth switching tube Q13, a fourteenth switching tube Q14, a fifteenth switching tube Q15, a sixteenth switching tube Q16, and a short-circuit protection unit 130.

An input end of the thirteenth switching tube Q13 is connected with the first end of the photovoltaic module 110; the output end of the thirteenth switching tube Q13 is connected with the input end of the fourteenth switching tube Q14; the output end of the fourteenth switching tube Q14 is connected with the input end of the fifteenth switching tube Q15; the output end of the fifteenth switching tube Q15 is connected with the input end of the sixteenth switching tube Q16; an output end of the sixteenth switching tube Q16 is connected with the second end of the photovoltaic module 110; the short-circuit protection unit 130 is connected in parallel with the sixteenth switching tube Q16; the anode terminal of the third diode D3 is taken as the midpoint terminal of the bridge arm 120; the cathode terminal of the third diode D3 is connected with the output terminal of the thirteenth switching tube Q13; the anode end of the fourth diode D4 is connected with the anode end of the third diode D3; the cathode terminal of the fourth diode D4 is connected to the output terminal of the fifteenth switching transistor Q5.

Specifically, the photovoltaic inverter shown in fig. 5 is different from the photovoltaic inverter shown in fig. 3 only in the arrangement structure of the bridge arm 120, and the rest is the same, and the description thereof is omitted here.

Based on the above embodiments, optionally, in combination with fig. 2 to 5, the photovoltaic module 110 includes: a photovoltaic unit 111, an anti-reverse-flow diode D5, an inductive energy storage unit 112, and a capacitive energy storage unit 113;

A first end of the inductive energy storage unit 112 is connected to a first end of the photovoltaic unit 111; the second end of the inductance energy storage unit 112 is connected with the anode end of the anti-reflux diode D5; the third end of the inductive energy storage unit 112 is connected with the second end of the photovoltaic unit 111; the cathode terminal of the anti-reverse diode D5 is used as the first terminal of the photovoltaic module 110; a first end of the capacitance energy storage unit 113 is connected with a cathode end of the anti-backflow diode D5; a second end of the capacitive storage unit 113 serves as a second end of the photovoltaic module 110; the third terminal of the capacitive storage unit 113 serves as the third terminal of the photovoltaic module 110.

Specifically, the photovoltaic unit 111 delivers current to the bridge arm 120 through the reverse current prevention diode D5, and the bridge arm 120 converts direct current output from the photovoltaic unit 111 into alternating current and supplies the alternating current to the load. The inductive energy storage unit 112 and the capacitive energy storage unit 113 are used for voltage stabilization.

Based on the above embodiments, optionally, with continued reference to fig. 2-5, the inductive energy storage unit 112 includes: a first inductor L1 and an energy storage switching tube Q17; a first end of the first inductor L1 is connected to a first end of the photovoltaic unit 111; the second end of the first inductor L1 is connected with the input end of the energy storage switch tube Q17; an output terminal of the energy storage switching tube Q17 is connected to a second terminal of the photovoltaic unit 111.

The capacitive energy storage unit 113 includes: a first capacitor C1 and a second capacitor C2; a first end of the first capacitor C1 serves as a first end of the capacitor storage unit 113; the second end of the first capacitor C1 is used as the third end of the capacitor energy storage unit 113; the first end of the second capacitor C2 is connected with the second end of the first capacitor C1; the second terminal of the second capacitor C2 serves as the second terminal of the capacitive storage unit 113.

It should be appreciated that various forms of the flows shown above may be used to reorder, add, or delete steps. For example, the steps described in the present utility model may be performed in parallel, sequentially, or in a different order, so long as the desired results of the technical solution of the present utility model are achieved, and the present utility model is not limited herein.

The above embodiments do not limit the scope of the present utility model. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included in the scope of the present utility model.

Claims (10)

1. A photovoltaic inverter, comprising:

the photovoltaic module is used for converting light energy into electric energy;

At least three bridge arms connected in parallel with each other; the bridge arm comprises a short-circuit protection unit; the first end of the bridge arm is connected with the first end of the photovoltaic module; the second end of the bridge arm is connected with the second end of the photovoltaic module; the midpoint end of the bridge arm is connected with the third end of the photovoltaic module; the short-circuit protection unit is correspondingly and electrically connected with the bridge arm, and the bridge arm is used for converting direct current output by the photovoltaic module into alternating current; the short-circuit protection unit is used for preventing the photovoltaic module from being short-circuited to the ground through a load.

2. The photovoltaic inverter of claim 1 wherein the bridge arms are each of a T-shaped inverter configuration; the T-shaped bridge arm comprises: the first bridge arm, the second bridge arm and the third bridge arm;

The first end of the first bridge arm is used as a midpoint end of the bridge arm; the first end of the second bridge arm is used as the first end of the bridge arm; the second end of the second bridge arm is connected with the second end of the first bridge arm; the first end of the third bridge arm is connected with the second end of the second bridge arm; and the second end of the third bridge arm is used as the second end of the bridge arm.

3. The photovoltaic inverter of claim 1 wherein the legs are all I-shaped legs.

4. The photovoltaic inverter of claim 2, wherein the first leg comprises: a first switching tube and a second switching tube; the second bridge arm includes: a third switching tube; the third leg includes: a fourth switching tube and a short-circuit protection unit;

the input end of the first switching tube is used as a first end of the first bridge arm; the output end of the first switching tube is connected with the output end of the second switching tube; the input end of the second switching tube is used as a second end of the first bridge arm; the input end of the third switching tube is used as the first end of the second bridge arm; the output end of the third switching tube is used as a second end of the second bridge arm; the input end of the fourth switching tube is used as the first end of the third bridge arm; the output end of the fourth switching tube is connected with the first end of the short-circuit protection unit; and the second end of the short-circuit protection unit is used as the second end of the third bridge arm.

5. The photovoltaic inverter of claim 2, wherein the first leg comprises: a fifth switching tube and a sixth switching tube; the second bridge arm includes: a seventh switching tube; the third leg includes: an eighth switching tube and a short-circuit protection unit;

The input end of the fifth switching tube is used as a first end of the first bridge arm; the output end of the fifth switching tube is connected with the output end of the sixth switching tube; the input end of the sixth switching tube is used as the second end of the first bridge arm; the input end of the seventh switching tube is used as the first end of the second bridge arm; the output end of the seventh switching tube is used as a second end of the second bridge arm; the input end of the eighth switching tube is used as the first end of the third bridge arm; the output end of the eighth switching tube is used as the second end of the third bridge arm; the short-circuit protection unit is connected in parallel with the eighth switching tube.

6. The photovoltaic inverter of claim 3 wherein the bridge arms comprise: a first diode, a second diode, a ninth switching tube, a tenth switching tube, an eleventh switching tube, a twelfth switching tube and a short-circuit protection unit;

The input end of the ninth switching tube is connected with the first end of the photovoltaic module; the output end of the ninth switching tube is connected with the input end of the tenth switching tube; the output end of the tenth switching tube is connected with the input end of the eleventh switching tube; the output end of the eleventh switching tube is connected with the input end of the twelfth switching tube; the output end of the twelfth switching tube is connected with the first end of the short-circuit protection unit; the second end of the short-circuit protection unit is connected with the second end of the photovoltaic module; the anode end of the first diode is used as the midpoint end of the bridge arm; the cathode end of the first diode is connected with the output end of the ninth switching tube; the anode end of the second diode is connected with the anode end of the first diode; and the cathode end of the second diode is connected with the output end of the eleventh switching tube.

7. The photovoltaic inverter of claim 3 wherein the bridge arms comprise: a third diode, a fourth diode, a thirteenth switching tube, a fourteenth switching tube, a fifteenth switching tube, a sixteenth switching tube and a short-circuit protection unit;

The input end of the thirteenth switching tube is connected with the first end of the photovoltaic module; the output end of the thirteenth switching tube is connected with the input end of the fourteenth switching tube; the output end of the fourteenth switching tube is connected with the input end of the fifteenth switching tube; the output end of the fifteenth switching tube is connected with the input end of the sixteenth switching tube; the output end of the sixteenth switching tube is connected with the second end of the photovoltaic module; the short-circuit protection unit is connected with the sixteenth switching tube in parallel; the anode end of the third diode is used as the midpoint end of the bridge arm; the cathode end of the third diode is connected with the output end of the thirteenth switching tube; the anode end of the fourth diode is connected with the anode end of the third diode; and the cathode end of the fourth diode is connected with the output end of the fifteenth switching tube.

8. The photovoltaic inverter of claim 1 wherein the short circuit protection unit is a switching tube.

9. The photovoltaic inverter of claim 1 wherein the photovoltaic module comprises: the photovoltaic device comprises a photovoltaic unit, an anti-backflow diode, an inductive energy storage unit and a capacitive energy storage unit;

The first end of the inductance energy storage unit is connected with the first end of the photovoltaic unit; the second end of the inductance energy storage unit is connected with the anode end of the anti-backflow diode; the third end of the inductance energy storage unit is connected with the second end of the photovoltaic unit; the cathode end of the anti-reflux diode is used as a first end of the photovoltaic module; the first end of the capacitor energy storage unit is connected with the cathode end of the anti-countercurrent diode; the second end of the capacitive energy storage unit is used as the second end of the photovoltaic module; and the third end of the capacitive energy storage unit is used as the third end of the photovoltaic module.

10. The photovoltaic inverter of claim 9 wherein the inductive energy storage unit comprises: the first inductor and the energy storage switch tube;

The first end of the first inductor is connected with the first end of the photovoltaic unit; the second end of the first inductor is connected with the input end of the energy storage switch tube; the output end of the energy storage switch tube is connected with the second end of the photovoltaic unit;

The capacitive energy storage unit includes: a first capacitor and a second capacitor;

The first end of the first capacitor is used as the first end of the capacitor energy storage unit; the second end of the first capacitor is used as a third end of the capacitor energy storage unit; the first end of the second capacitor is connected with the second end of the first capacitor; the second end of the second capacitor is used as the second end of the capacitor energy storage unit.