Photovoltaic inverter

Abstract

The embodiment of the invention discloses a photovoltaic inverter, relates to the technical field of energy, and solves the problem of how to timely control an inverter circuit to stop working so as to improve the safety and reliability of the photovoltaic inverter under the condition that differential-mode lightning stroke occurs in the photovoltaic inverter. The photovoltaic inverter comprises a controller, a DC port, an inverter circuit, a first lightning protection device, three first inductors, three first capacitors, three second lightning protection devices and a three-phase AC port. The three-phase output end of the inverter circuit is connected with the first ends of the three first inductors respectively, the second ends of the three first inductors are connected with the three-phase alternating current port respectively, the first ends of the three first capacitors are connected with the second ends of the three first inductors respectively, and the second ends of the three first capacitors are used for being connected with the grounding end. And the controller is used for detecting the voltage of the three-phase alternating current port, and controlling the inverter circuit to stop working under the condition that the voltage of at least one phase alternating current port is greater than a voltage threshold.

Description

Technical Field

[0001] The present application relates to the field of energy technology, and in particular to a photovoltaic inverter. Background Art

[0002] During the operation of a PV inverter, differential-mode lightning strikes may occur between phase lines or between phase and neutral lines, which will result in a high risk of damage to the PV inverter.

[0003] The three-phase AC ports of a photovoltaic inverter can each be connected to a lightning arrester (SPD). This device protects against common-mode or differential-mode lightning strikes, thereby improving the safety and reliability of the photovoltaic inverter. However, some differential-mode lightning energy can still form a return path through the inverter capacitor and inverter circuit in the photovoltaic inverter, increasing the risk of failure of the switching transistors in the inverter circuit and damaging the photovoltaic inverter. The controller in the photovoltaic inverter can detect the current in the inverter inductor using a Hall current sensor. If the current in the inverter inductor exceeds the current threshold, the inverter circuit is controlled to stop operation, further improving the safety and reliability of the photovoltaic inverter.

[0004] However, due to the electromagnetic induction of the inverter inductor, there is a significant delay in the current conversion of the inverter inductor. Furthermore, there are delays in the sampling of the Hall effect current sensor and the processing of the controller software. As a result, the controller cannot promptly stop the inverter circuit in the event of a differential-mode lightning strike, which will result in a high risk of damage to the PV inverter. Therefore, how to promptly stop the inverter circuit in the event of a differential-mode lightning strike to improve the safety and reliability of the PV inverter has become an urgent problem that needs to be solved. Summary of the Invention

[0005] The embodiments of the present application provide a photovoltaic inverter that solves the problem of how to promptly control the inverter circuit to stop working when a differential-mode lightning strike occurs in the photovoltaic inverter, thereby improving the safety and reliability of the photovoltaic inverter.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions:

[0007] According to a first aspect of an embodiment of the present application, a photovoltaic inverter is provided, comprising a controller, a DC port, an inverter circuit, a first lightning arrester, three first inductors, three first capacitors, three second lightning arresters, and a three-phase AC port. The DC port is used to connect to a photovoltaic array, and the three-phase AC port is used to connect to a power grid or load. The input end of the inverter circuit is connected to the DC port, the three-phase output ends of the inverter circuit are respectively connected to the first ends of the three first inductors, the second ends of the three first inductors are respectively connected to the three-phase AC port, the first ends of the three first capacitors are respectively connected to the second ends of the three first inductors, the second ends of the three first capacitors are respectively connected to a ground terminal, the first ends of the three second lightning arresters are respectively connected to the three-phase AC port, the second ends of the three second lightning arresters are respectively connected to the first end of the first lightning arrester, and the second ends of the first lightning arrester are connected to a ground terminal. The controller is used to detect the voltage of the three-phase AC port and control the inverter circuit to stop operating when the voltage of at least one phase AC port is greater than a voltage threshold. The first inductor can be referred to as an inverter inductor.

[0008] Due to the electromagnetic induction phenomenon of the inverter inductor, there is a large delay in the current conversion of the inverter inductor. In the prior art, when a differential-mode lightning strikes a photovoltaic inverter, the controller controls the inverter circuit to stop working based on the current of the inverter inductor. However, this will not be able to stop the inverter circuit in time, resulting in a high risk of damage to the photovoltaic inverter. Based on this solution, when a differential-mode lightning strikes a photovoltaic inverter, the controller controls the inverter circuit to stop working based on the voltage of the three-phase AC port. The voltage conversion delay of the three-phase AC port is smaller, so the controller can control the inverter circuit to stop working in time, which can improve the safety and reliability of the photovoltaic inverter.

[0009] In combination with the first aspect, in one embodiment, the controller is further configured to control the inverter circuit to stop operating when an average value of the voltage of at least one phase AC port is greater than a voltage threshold within a preset time.

[0010] Based on this solution, it is possible to avoid the situation where the voltage of at least one phase AC port accidentally jumps and the controller malfunctions to control the inverter circuit to stop working, thereby improving the reliability of the photovoltaic inverter.

[0011] In combination with the first aspect, in one embodiment, the controller is further configured to control the inverter circuit to resume normal operation when the time for controlling the inverter circuit to stop operating is greater than or equal to a time threshold.

[0012] Based on this solution, the working state of the photovoltaic inverter can be restored in time, thereby improving the power supply continuity and reliability of the photovoltaic power generation system.

[0013] According to a second aspect of an embodiment of the present application, a photovoltaic inverter is provided, comprising a controller, a DC port, an inverter circuit, a first lightning arrester, three first inductors, three first capacitors, three second lightning arresters, and a three-phase AC port, wherein the DC port is used to connect to a photovoltaic array, and the three-phase AC port is used to connect to a power grid or a load. The input end of the inverter circuit is connected to the DC port, the three-phase output end of the inverter circuit is respectively connected to the first end of the three first inductors, the second ends of the three first inductors are respectively connected to the three-phase AC port, the first ends of the three first capacitors are respectively connected to the second ends of the three first inductors, the second ends of the three first capacitors are respectively connected to a ground terminal, the first ends of the three second lightning arresters are respectively connected to the three-phase AC port, the second ends of the three second lightning arresters are respectively connected to the first end of the first lightning arrester, and the second end of the first lightning arrester is connected to a ground terminal. The controller is used to detect the current of the three first capacitors and control the inverter circuit to stop working when the current of at least one first capacitor is greater than a first current threshold.

[0014] Due to the electromagnetic induction phenomenon of the inverter inductor, there is a large delay in the current conversion of the inverter inductor. In the prior art, when a differential-mode lightning strike occurs in a photovoltaic inverter, the controller controls the inverter circuit to stop working based on the current of the inverter inductor. However, it will not be able to control the inverter circuit to stop working in time, which will result in a high risk of damage to the photovoltaic inverter. Based on this solution, when a differential-mode lightning strike occurs in a photovoltaic inverter, the controller controls the inverter circuit to stop working based on the current of the three first capacitors. The current conversion delay of the three first capacitors is smaller, so that the controller can control the inverter circuit to stop working in time, which can improve the safety and reliability of the photovoltaic inverter.

[0015] In combination with the second aspect, in one embodiment, the controller is further configured to control the inverter circuit to stop operating when an average current of at least one first capacitor is greater than a first current threshold within a preset time.

[0016] Based on this solution, it is possible to avoid the controller malfunctioning and causing the inverter circuit to stop working when the current of at least one first capacitor accidentally jumps, thereby improving the reliability of the photovoltaic inverter.

[0017] In combination with the second aspect, in one embodiment, the controller is further configured to control the inverter circuit to resume normal operation when the time for controlling the inverter circuit to stop operating is greater than or equal to a time threshold.

[0018] Based on this solution, the working state of the photovoltaic inverter can be restored in time, thereby improving the power supply continuity and reliability of the photovoltaic power generation system.

[0019] According to a third aspect of the embodiments of the present application, a photovoltaic inverter is provided, comprising a controller, a DC port, an inverter circuit, a first lightning arrester, three first inductors, three first capacitors, three second lightning arresters, a three-phase AC port, and three second inductors. The DC port is used to connect to a photovoltaic array, and the three-phase AC port is used to connect to a power grid or a load. The input end of the inverter circuit is connected to the DC port, the three-phase output ends of the inverter circuit are respectively connected to the first ends of the three first inductors, the second ends of the three first inductors are respectively connected to the three-phase AC port, the first ends of the three first capacitors are respectively connected to the second ends of the three first inductors, and the second ends of the three first capacitors are each connected to a ground terminal. The first ends of the three second lightning arresters are respectively connected to the three-phase AC port, the second ends of the three second lightning arresters are each connected to the first end of the first lightning arrester, and the second end of the first lightning arrester is connected to a ground terminal. The three second inductors are respectively connected between the second ends of the three first inductors and the three-phase AC port. The controller is used to detect the current of the three second inductors and control the inverter circuit to stop operating when the current of at least one second inductor is greater than a second current threshold.

[0020] Due to the electromagnetic induction phenomenon of the inverter inductor, there is a large delay in the current conversion of the inverter inductor. In the prior art, when a differential-mode lightning strikes a photovoltaic inverter, the controller controls the inverter circuit to stop working based on the current of the inverter inductor. However, it will not be able to control the inverter circuit to stop working in time, which will result in a high risk of damage to the photovoltaic inverter. Based on this solution, when a differential-mode lightning strikes a photovoltaic inverter, the controller controls the inverter circuit to stop working based on the current of the three second inductors. The current conversion delay of the three second inductors is smaller, so the controller can control the inverter circuit to stop working in time, which can improve the safety and reliability of the photovoltaic inverter.

[0021] In combination with the third aspect, in one embodiment, the controller is further configured to control the inverter circuit to stop operating when an average current of at least one second inductor is greater than a second current threshold within a preset time.

[0022] Based on this solution, it is possible to avoid the controller malfunctioning and causing the inverter circuit to stop working when the current of at least one second inductor accidentally jumps, thereby improving the reliability of the photovoltaic inverter.

[0023] In combination with the third aspect, in one embodiment, the controller is further configured to control the inverter circuit to resume normal operation when the time for controlling the inverter circuit to stop operating is greater than or equal to a time threshold.

[0024] Based on this solution, the working state of the photovoltaic inverter can be restored in time, thereby improving the power supply continuity and reliability of the photovoltaic power generation system.

[0025] According to a fourth aspect of the embodiments of the present application, a photovoltaic inverter is provided, comprising a controller, a DC port, an inverter circuit, a first lightning arrester, three first inductors, three first capacitors, three second lightning arresters, a three-phase AC port, three second inductors, and three second capacitors, wherein the DC port is used to connect to a photovoltaic array, and the three-phase AC port is used to connect to a power grid or a load. The input end of the inverter circuit is connected to the DC port, the three-phase output ends of the inverter circuit are respectively connected to the first ends of the three first inductors, the second ends of the three first inductors are respectively connected to the three-phase AC port, the first ends of the three first capacitors are respectively connected to the second ends of the three first inductors, the second ends of the three first capacitors are each connected to a ground terminal, the first ends of the three second lightning arresters are respectively connected to the three-phase AC port, the second ends of the three second lightning arresters are each connected to the first end of the first lightning arrester, the second end of the first lightning arrester is connected to a ground terminal, the three second inductors are respectively connected between the second ends of the three first inductors and the three-phase AC port, the first ends of the three second capacitors are respectively connected to the first ends of the three second lightning arresters, and the second ends of the three second capacitors are each connected to a ground terminal. The controller is used to detect the currents of the three second capacitors, and control the inverter circuit to stop working when the current of at least one second capacitor is greater than a third current threshold.

[0026] Due to the electromagnetic induction phenomenon of the inverter inductor, there is a large delay in the current conversion of the inverter inductor. In the prior art, when a differential-mode lightning strike occurs in a photovoltaic inverter, the controller controls the inverter circuit to stop working based on the current of the inverter inductor. However, it will not be able to control the inverter circuit to stop working in time, which will result in a high risk of damage to the photovoltaic inverter. Based on this solution, when a differential-mode lightning strike occurs in a photovoltaic inverter, the controller controls the inverter circuit to stop working based on the current of the three second capacitors. The current conversion delay of the three second capacitors is smaller, so that the controller can control the inverter circuit to stop working in time, which can improve the safety and reliability of the photovoltaic inverter.

[0027] In combination with the fourth aspect, in one embodiment, the controller is further configured to control the inverter circuit to stop operating when an average current of at least one second capacitor is greater than a third current threshold within a preset time.

[0028] Based on this solution, it is possible to avoid the controller malfunctioning and causing the inverter circuit to stop working when the current of at least one second capacitor accidentally jumps, thereby improving the reliability of the photovoltaic inverter.

[0029] In combination with the fourth aspect, in one embodiment, the controller is further configured to control the inverter circuit to resume normal operation when the time for controlling the inverter circuit to stop operating is greater than or equal to a time threshold.

[0030] Based on this solution, the working state of the photovoltaic inverter can be restored in time, thereby improving the power supply continuity and reliability of the photovoltaic power generation system.

[0031] According to a fifth aspect of the embodiments of the present application, a control method for a photovoltaic inverter is provided, which is applied to a photovoltaic inverter. The photovoltaic inverter includes a DC port, an inverter circuit, a first lightning arrester, three first inductors, three first capacitors, three second lightning arresters, and a three-phase AC port. The DC port is used to connect to a photovoltaic array, and the three-phase AC port is used to connect to a power grid or a load. The input end of the inverter circuit is connected to the DC port, the three-phase output ends of the inverter circuit are respectively connected to the first ends of the three first inductors, the second ends of the three first inductors are respectively connected to the three-phase AC port, the first ends of the three first capacitors are respectively connected to the second ends of the three first inductors, the second ends of the three first capacitors are each connected to a ground terminal, the first ends of the three second lightning arresters are respectively connected to the three-phase AC port, the second ends of the three second lightning arresters are each connected to the first end of the first lightning arrester, and the second end of the first lightning arrester is connected to a ground terminal. The method includes: detecting the voltage of the three-phase AC port, and controlling the inverter circuit to stop operating when the voltage of at least one phase AC port is greater than a voltage threshold.

[0032] According to a sixth aspect of the embodiments of the present application, a control method for a photovoltaic inverter is provided, which is applied to a photovoltaic inverter. The photovoltaic inverter includes a DC port, an inverter circuit, a first lightning arrester, three first inductors, three first capacitors, three second lightning arresters, and a three-phase AC port. The DC port is used to connect to a photovoltaic array, and the three-phase AC port is used to connect to a power grid or a load. The input end of the inverter circuit is connected to the DC port, the three-phase output end of the inverter circuit is respectively connected to the first end of the three first inductors, the second ends of the three first inductors are respectively connected to the three-phase AC port, the first ends of the three first capacitors are respectively connected to the second ends of the three first inductors, the second ends of the three first capacitors are each connected to a ground terminal, the first ends of the three second lightning arresters are respectively connected to the three-phase AC port, the second ends of the three second lightning arresters are each connected to the first end of the first lightning arrester, and the second end of the first lightning arrester is connected to a ground terminal. The method includes: detecting the current of the three first capacitors, and when the current of at least one first capacitor is greater than a first current threshold, controlling the inverter circuit to stop operating.

[0033] In a seventh aspect of the embodiments of the present application, a control method for a photovoltaic inverter is provided, which is applied to a photovoltaic inverter. The photovoltaic inverter includes a DC port, an inverter circuit, a first lightning arrester, three first inductors, three first capacitors, three second lightning arresters, a three-phase AC port, and three second inductors. The DC port is used to connect to a photovoltaic array, and the three-phase AC port is used to connect to a power grid or a load. The input end of the inverter circuit is connected to the DC port, the three-phase output ends of the inverter circuit are respectively connected to the first ends of the three first inductors, the second ends of the three first inductors are respectively connected to the three-phase AC port, the first ends of the three first capacitors are respectively connected to the second ends of the three first inductors, and the second ends of the three first capacitors are each connected to a ground terminal. The first ends of the three second lightning arresters are respectively connected to the three-phase AC port, the second ends of the three second lightning arresters are each connected to the first end of the first lightning arrester, and the second end of the first lightning arrester is connected to a ground terminal. The three second inductors are respectively connected between the second ends of the three first inductors and the three-phase AC port. The method includes: detecting the current of the three second inductors, and controlling the inverter circuit to stop operating when the current of at least one second inductor is greater than a second current threshold.

[0034] In an eighth aspect of the embodiments of the present application, a control method for a photovoltaic inverter is provided, which is applied to a photovoltaic inverter, the photovoltaic inverter comprising a DC port, an inverter circuit, a first lightning arrester, three first inductors, three first capacitors, three second lightning arresters, a three-phase AC port, three second inductors, and three second capacitors, wherein the DC port is used to connect to a photovoltaic array, and the three-phase AC port is used to connect to a power grid or a load. The input end of the inverter circuit is connected to the DC port, the three-phase output ends of the inverter circuit are respectively connected to the first ends of the three first inductors, the second ends of the three first inductors are respectively connected to the three-phase AC port, the first ends of the three first capacitors are respectively connected to the second ends of the three first inductors, the second ends of the three first capacitors are each connected to a ground terminal, the first ends of the three second lightning arresters are respectively connected to the three-phase AC port, the second ends of the three second lightning arresters are each connected to the first end of the first lightning arrester, the second end of the first lightning arrester is connected to a ground terminal, the three second inductors are respectively connected between the second ends of the three first inductors and the three-phase AC port, the first ends of the three second capacitors are respectively connected to the first ends of the three second lightning arresters, and the second ends of the three second capacitors are each connected to a ground terminal. The method includes: detecting currents of three second capacitors, and controlling the inverter circuit to stop working when the current of at least one second capacitor is greater than a third current threshold.

[0035] The description of the fifth aspect in this application may refer to the detailed description of the first aspect; and, the beneficial effects of the fifth aspect may refer to the analysis of the beneficial effects of the first aspect; the description of the sixth aspect in this application may refer to the detailed description of the second aspect; and, the beneficial effects of the sixth aspect may refer to the analysis of the beneficial effects of the second aspect; the description of the seventh aspect in this application may refer to the detailed description of the third aspect; and, the beneficial effects of the seventh aspect may refer to the analysis of the beneficial effects of the third aspect; the description of the eighth aspect in this application may refer to the detailed description of the fourth aspect; and, the beneficial effects of the eighth aspect may refer to the analysis of the beneficial effects of the fourth aspect, and no further details will be given here. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of a circuit topology of a photovoltaic power generation system;

[0037] Figure 2 This is a circuit topology diagram of another photovoltaic power generation system;

[0038] Figure 3 This is a schematic diagram of a circuit topology of a photovoltaic inverter;

[0039] Figure 4 A schematic diagram of a change curve of current and voltage in a photovoltaic inverter;

[0040] Figure 5 A schematic diagram of a circuit topology for an application scenario of a photovoltaic inverter provided in an embodiment of the present application;

[0041] Figure 6 A schematic diagram of a circuit topology of a photovoltaic inverter provided in an embodiment of the present application;

[0042] Figure 7 A schematic diagram of a curve showing changes in current and voltage in a photovoltaic inverter provided in an embodiment of the present application;

[0043] Figure 8 A schematic diagram of another circuit topology of a photovoltaic inverter provided in an embodiment of the present application;

[0044] Figure 9 A schematic diagram of a circuit topology of another photovoltaic inverter provided in an embodiment of the present application;

[0045] Figure 10 A schematic flow chart of a photovoltaic inverter control method provided in an embodiment of the present application;

[0046] Figure 11 A schematic flow chart of another photovoltaic inverter control method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0047] The following sections discuss the making and use of various embodiments in detail. However, it should be understood that many applicable inventive concepts provided herein can be implemented in a variety of specific contexts. The specific embodiments discussed are intended merely to illustrate specific ways to implement and use the present description and technology and are not intended to limit the scope of this application.

[0048] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art.

[0049] Various circuits or other components may be described or referred to as being "configured to" perform one or more tasks. In this case, "configured to" is used to imply structure by indicating that the circuit / component includes structure (e.g., circuitry) that performs the one or more tasks during operation. Thus, even when a specified circuit / component is not currently operational (e.g., not turned on), the circuit / component may be referred to as being configured to perform the task. Circuits / components used with the phrase "configured to" include hardware, such as circuitry that performs an operation, etc.

[0050] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings. In this application, "at least one / phase" refers to one / phase or multiple / phases, and "multiple / phases" refers to two / phases or more than two / phases. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. In the embodiments of the present application, words such as "first" and "second" do not limit the quantity or order.

[0051] In this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described in this application as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0052] Before introducing the embodiments of the present application, the background technology involved in the present application is first introduced.

[0053] like Figure 1 Figure 1 shows a schematic circuit topology diagram of a photovoltaic power generation system 100. This photovoltaic power generation system 100 includes a photovoltaic inverter 110. The DC port of the photovoltaic inverter 110 is used to connect to a photovoltaic array 200, and the three-phase AC port of the photovoltaic inverter 110 is used to connect to a power grid or load 300. The photovoltaic array 200 is used to convert solar energy into DC power, and the photovoltaic inverter 110 is used to convert this DC power into AC power and transmit it to the power grid or load 300.

[0054] In one embodiment, reference Figure 1The photovoltaic power generation system 100 may further include an energy storage battery 120 and a power conversion system (PCS) 130. The electrodes of the energy storage battery 120 are connected to the DC port of the energy storage converter 130, and the three-phase AC port of the energy storage converter 130 is connected to the three-phase AC port of the photovoltaic inverter 110. The energy storage converter 130 is used to convert the AC power output by the photovoltaic inverter 110 into DC power, or to convert the AC power provided by the power grid or load 300 into DC power to charge the energy storage battery 120. The energy storage converter 130 is also used to convert the DC power output by the energy storage battery 120 into AC power to provide power to the power grid or load 300.

[0055] like Figure 2 FIG2 shows a schematic diagram of the circuit topology of another photovoltaic power generation system 100. The photovoltaic inverter 110 includes a DC port 111, an inverter circuit 112, and a three-phase AC port 113. The energy storage converter 130 includes a DC port 131, a bidirectional power conversion circuit 132, and a three-phase AC port 133. The difference between the photovoltaic inverter 110 and the energy storage converter 130 is that the inverter circuit 112 in the photovoltaic inverter 110 is used to convert DC power into AC power, while the bidirectional power conversion circuit 132 in the energy storage converter 130 is used to convert DC power into AC power and also to convert AC power into DC power. The similarity between the photovoltaic inverter 110 and the energy storage converter 130 is that both the inverter circuit 112 and the bidirectional power conversion circuit 132 include switching transistors, and both have AC sides connected to the power grid or load 300. Therefore, when a differential-mode lightning strike occurs, the differential-mode lightning strike protection schemes of the photovoltaic inverter 110 and the energy storage converter 130 can refer to each other. The embodiment of the present application takes the photovoltaic inverter 110 as an example to introduce the differential-mode lightning strike protection schemes of the photovoltaic inverter 110 and the energy storage converter 130.

[0056] like Figure 3 Figure 1 shows a schematic diagram of a circuit topology of a photovoltaic inverter 110. The photovoltaic inverter 110 includes a DC port 111, an inverter circuit 112, three first inductors L1, three first capacitors C1, three second inductors L2, three second capacitors C2, and a three-phase AC port 113. The DC port 111 is used to connect to a photovoltaic array 200, and the three-phase AC port 113 is used to connect to a power grid or load 300.

[0057] The input end of the inverter circuit 112 is connected to the DC port 111. The three-phase output ends of the inverter circuit 112 are respectively connected to the first ends of three first inductors L1, the second ends of the three first inductors L1 are respectively connected to the first ends of three second inductors L2, and the second ends of the three second inductors L2 are respectively connected to the three-phase AC port 113. The first ends of the three first capacitors C1 are respectively connected to the second ends of the three first inductors L1, and the second ends of the three first capacitors C1 are connected to the ground (G). The three second capacitors C2 are respectively connected between the three-phase AC port 113 and the ground. The three first inductors L1 can be referred to as inverter inductors, the three first capacitors C1 can be referred to as inverter capacitors, the three second inductors L2 can be referred to as port inductors, and the three second capacitors C2 can be referred to as port capacitors.

[0058] Reference Figure 3 During the operation of the photovoltaic inverter 110, a differential mode lightning strike may occur between the phase line and the phase line (LL), or a differential mode lightning strike may occur between the phase line and the neutral line (LN), which will cause a high risk of damage to the photovoltaic inverter 110.

[0059] Reference Figure 3 The photovoltaic inverter 110 may further include a first lightning arrester SPD1 and three second lightning arresters SPD2, which may also be referred to as surge protectors or surge protection devices (SPDs). The first ends of the three second lightning arresters SPD2 are respectively connected to the three-phase AC port 113, and the second ends of the three second lightning arresters SPD2 are all connected to the first end of the first lightning arrester SPD1. The second end of the first lightning arrester SPD1 is used to connect to the ground terminal. The first lightning arrester SPD1 may also be referred to as a common lightning arrester. The first lightning arrester SPD1 and the three second lightning arresters SPD2 are used to protect against common-mode lightning strikes or differential-mode lightning strikes, thereby improving the safety and reliability of the photovoltaic inverter 110.

[0060] Although the two second lightning arresters SPD2 connected in series between the phase lines can clamp the differential-mode lightning energy between the phase lines, some of the differential-mode lightning energy can still form a return path through the three first capacitors C1 (inverter capacitors) and the inverter circuit 112, which will lead to a higher risk of failure of the switch tube in the inverter circuit 112 and a higher risk of damage to the photovoltaic inverter 110.

[0061] Reference Figure 3The photovoltaic inverter 110 may further include a controller 114 and three Hall current sensors H. The controller 114 may detect the currents of the three first inductors L1 (inversion inductors) through the three Hall current sensors H. When the currents of the three first inductors L1 are greater than a current threshold, the controller 114 controls the inverter circuit 112 to stop operating and controls the switch tubes in the inverter circuit 112 to be in an off state, thereby further improving the safety and reliability of the photovoltaic inverter 110.

[0062] However, due to the electromagnetic induction phenomenon of the first inductor L1, there is a large delay in the current conversion of the first inductor L1. At the same time, there is a delay in the sampling of the Hall current sensor H and a delay in the software processing of the controller 114. The controller 114 cannot control the inverter circuit 112 to stop working in time when a differential mode lightning strikes the photovoltaic inverter 110, which will result in a high risk of damage to the photovoltaic inverter 110.

[0063] For example, Figure 4 Figure 1 shows a schematic diagram of the current and voltage curves in a photovoltaic inverter 110. At time T1, a differential-mode lightning strike strikes the photovoltaic inverter 110, causing the line voltage Uab between the A-phase and B-phase AC ports of the three-phase AC port 113 to rise rapidly. Due to the inherent characteristics of the first inductor L1, there is a significant delay in the current conversion of the first inductor L1. At time T2, the current in the first inductor L1 begins to increase. When the current in the first inductor L1 exceeds the current threshold, due to the sampling delay of the Hall current sensor H and the software processing delay of the controller 114, the controller 114 controls the inverter circuit 112 to stop operating at time T3. However, at time T3, the current in the first inductor L1 exceeds the switch current stress threshold, resulting in a high risk of failure of the switch in the inverter circuit 112 and a high risk of damage to the photovoltaic inverter 110.

[0064] Therefore, when a differential-mode lightning strike occurs in the photovoltaic inverter 110 , how to promptly control the inverter circuit to stop working so as to improve the safety and reliability of the photovoltaic inverter 110 becomes an urgent problem to be solved.

[0065] Based on this, an embodiment of the present application provides a photovoltaic inverter, in which a controller controls the inverter circuit to stop working according to the voltage or current with lower delay in the photovoltaic inverter, so that when a differential mode lightning strike occurs in the photovoltaic inverter, the inverter circuit can be controlled to stop working in time, thereby improving the safety and reliability of the photovoltaic inverter.

[0066] like Figure 5 As shown, the photovoltaic inverter 400 provided in the embodiment of the present application can be an independent device.

[0067] like Figure 5, which is a schematic diagram of a circuit topology for an application scenario of a photovoltaic inverter 400 provided in an embodiment of the present application. The photovoltaic inverter 400 can be applied to a photovoltaic power generation system 500. The photovoltaic inverter 400 includes a DC port 410 and a three-phase AC port 420. The DC port 410 is used to connect to the output of the photovoltaic array 200, and the three-phase AC port 420 is used to connect to the power grid or load 300. The photovoltaic array 200 is used to convert solar energy into DC power, and the photovoltaic inverter 400 is used to convert the DC power into AC power to provide power to the power grid or load 300.

[0068] In one implementation, the DC port 410 of the photovoltaic inverter 400 provided in the embodiment of the present application can be used to connect to a battery pack. The photovoltaic inverter 400 can also be referred to as a photovoltaic energy storage inverter.

[0069] In one embodiment, the differential-mode lightning protection solution for the photovoltaic inverter 400 provided in the embodiment of the present application can also be applied to energy storage converters, or other three-phase AC devices that need to be connected to the power grid or load 300, and the embodiment of the present application is not limited to this.

[0070] Reference Figure 5 The photovoltaic inverter 400 provided in the embodiment of the present application further includes a controller 430, an inverter circuit 440, a first lightning arrester SPD1, three first inductors L1, three first capacitors C1, and three second lightning arresters SPD2. The input end of the inverter circuit 440 is connected to the DC port 410, and the three-phase output ends of the inverter circuit 440 are respectively connected to the first ends of the three first inductors L1, and the second ends of the three first inductors L1 are respectively connected to the three-phase AC port 420. The first ends of the three first capacitors C1 are respectively connected to the second ends of the three first inductors L1, and the second ends of the three first capacitors C1 are all connected to the ground terminal G. The first ends of the three second lightning arresters SPD2 are respectively connected to the three-phase AC port 420, and the second ends of the three second lightning arresters SPD2 are all connected to the first end of the first lightning arrester SPD1, and the second end of the first lightning arrester SPD1 is connected to the ground terminal G. The three first inductors L1 can be referred to as inverter inductors, and the third first capacitor C1 can be referred to as inverter capacitor.

[0071] The controller 430 is used to detect the voltage of the three-phase AC port 420. When the voltage of at least one phase AC port is greater than the voltage threshold, the inverter circuit 440 is controlled to stop working. The specific value of the voltage threshold can be determined by the withstand voltage value or the withstand current value of the switching tube in the integrated inverter circuit 440. The embodiment of the present application does not limit the specific value of the voltage threshold.

[0072] In one embodiment, the controller 430 detects the voltage of the three-phase AC port 420. For example, the controller 430 detects the voltage of the A-phase AC port among the three-phase AC ports 420. The controller 430 detects the phase voltage between the A-phase AC port and the neutral line, thereby promptly controlling the inverter circuit 440 to stop operating in the event of a differential-mode lightning strike between the phase line and the neutral line of the photovoltaic inverter 400, thereby improving the safety and reliability of the photovoltaic inverter 400. Alternatively, the controller 430 detects the line voltage between the A-phase AC port and the B-phase AC port, or the controller 430 detects the line voltage between the A-phase AC port and the C-phase AC port, thereby promptly controlling the inverter circuit 440 to stop operating in the event of a differential-mode lightning strike between the phase lines of the photovoltaic inverter 400, thereby improving the safety and reliability of the photovoltaic inverter 400.

[0073] In one embodiment, reference Figure 5 The photovoltaic inverter 400 provided in the embodiment of the present application may be a three-phase three-wire photovoltaic inverter. The controller 430 detects the phase voltage between the A-phase AC port and the neutral line, including: the controller 430 calculates and determines the phase voltage of the A-phase AC port based on the line voltage of the A-phase AC port.

[0074] In one embodiment, the photovoltaic inverter 400 provided in the embodiment of the present application is a three-phase four-wire photovoltaic inverter. When the photovoltaic inverter 400 includes a neutral line (not shown in the figure), the above-mentioned controller 430 detects the phase voltage between the A-phase AC port and the neutral line, including: the controller 430 directly detects the phase voltage between the A-phase AC port and the neutral line.

[0075] In one embodiment, the above-mentioned controller 430 detects the voltage of the three-phase AC port 420, including: the controller 430 can use a voltage sensor such as a voltage transformer, a resistor divider or a Hall voltage sensor to detect the voltage of the three-phase AC port 420. The voltage sensor can be selected according to actual conditions. The embodiment of the present application does not limit the specific type of voltage sensor used.

[0076] In one embodiment, the controller 430 controls the inverter circuit 440 to stop working, which includes: the controller 430 controls the switch tube in the inverter circuit 440 to be in the off state.

[0077] In one embodiment, the controller 430 is further configured to control the inverter circuit 440 to stop operating if the average voltage of at least one AC port phase exceeds a voltage threshold within a preset time. The specific value of the preset time is not limited in this embodiment. This prevents the controller 430 from malfunctioning and causing the inverter circuit 440 to stop operating due to accidental fluctuations in the voltage of at least one AC port phase, thereby improving the reliability of the photovoltaic inverter 400.

[0078] In one embodiment, since the time when the photovoltaic inverter 400 is struck by differential mode lightning is generally short, the controller 430 is also used to control the inverter circuit 440 to resume normal operation when the time when the inverter circuit 440 stops working is greater than or equal to a time threshold, thereby restoring the working state of the photovoltaic inverter 400 in a timely manner and improving the power supply continuity and reliability of the photovoltaic power generation system 500.

[0079] In one embodiment, the controller 430 includes a digital signal processing (DSP) chip or a microcontroller unit (MCU), which can also be called a single-chip microcomputer. The controller 430 can be selected according to actual conditions. The embodiment of the present application does not limit the specific type of the controller 430.

[0080] In one embodiment, Figure 6 FIG. 4 is a schematic diagram of a circuit topology of a photovoltaic inverter 400 provided in an embodiment of the present application. The controller 430 may include a programmable logic device 431 and a comparator 432, which may also be referred to as a hardware comparator. The first input of the comparator 432 is used to receive the voltage value sampled by the voltage sampling circuit or, in the embodiments described below, the current value sampled by the current sampling circuit. The second input of the comparator 432 is used to receive a reference voltage, which indicates the voltage threshold or, in the embodiments described below, the current threshold. The output of the comparator 432 is used to send a stop instruction to the programmable logic device 431, which controls the inverter circuit 440 to stop operating according to the stop instruction. Compared to a case where the controller 430 determines whether the sampled voltage value is greater than the voltage threshold or the sampled current value is greater than the current threshold through software, the comparator 432 performs a faster comparison, allowing the controller 430 to more promptly stop the inverter circuit 440, further improving the safety and reliability of the photovoltaic inverter 400.

[0081] In one embodiment, the programmable logic device 431 includes a complex programmable logic device (CPLD) or a field programmable gate array (FPGA). The programmable logic device 431 can be selected according to actual conditions. The embodiment of the present application does not limit the specific type of the programmable logic device 431.

[0082] In one embodiment, reference Figure 6 The photovoltaic inverter 400 provided in the embodiment of the present application further includes a reference voltage regulator 450 , which is used to provide a reference voltage received by the second input terminal of the comparator 432 .

[0083] Due to the electromagnetic induction phenomenon of the first inductor L1 (inverter inductor), there is a large delay in the current conversion of the first inductor L1. In the event of a differential-mode lightning strike on the photovoltaic inverter 110, the controller 114 controls the inverter circuit 112 to stop working based on the current of the first inductor L1. However, it will not be able to control the inverter circuit 112 to stop working in a timely manner, which will result in a high risk of damage to the photovoltaic inverter 110. In the photovoltaic inverter 400 provided in the embodiment of the present application, in the event of a differential-mode lightning strike on the photovoltaic inverter 400, the controller 430 controls the inverter circuit 440 to stop working based on the voltage of the three-phase AC port 420. The voltage conversion delay of the three-phase AC port 420 is smaller, so that the controller 430 can control the inverter circuit 440 to stop working in a timely manner, thereby improving the safety and reliability of the photovoltaic inverter 400.

[0084] In one embodiment, referring to Figure 6 The controller 430 is also used to detect the current of the three first capacitors C1. When the current of at least one of the first capacitors C1 is greater than the first current threshold, the inverter circuit 440 is controlled to stop working. The specific value of the first current threshold can be determined by the withstand voltage value or the withstand current value of the switch tube in the integrated inverter circuit 440. The embodiment of the present application does not limit the specific value of the first current threshold.

[0085] In one embodiment, the controller 430 detects the current of the three first capacitors C1, and in the following embodiments, the controller 430 detects the current of other devices, including: the controller 430 can use a current sensor such as a Hall current sensor, an electromagnetic current sensor or a current transformer to detect the current of the three first capacitors C1. The current sensor can be selected according to actual conditions. The embodiment of the present application does not limit the specific type of current sensor used.

[0086] In one embodiment, the controller 430 is further configured to control the inverter circuit 440 to stop operating if the average current of the at least one first capacitor C1 exceeds a first current threshold within a preset time. The specific value of the preset time is not limited in this embodiment of the present application. This prevents the controller 430 from malfunctioning and causing the inverter circuit 440 to stop operating due to accidental fluctuations in the current of the at least one first capacitor C1, thereby improving the reliability of the photovoltaic inverter 400.

[0087] like Figure 7 The figure shows a schematic diagram of the change curve of current and voltage in a photovoltaic inverter 110 provided by an embodiment of the present application. At time T1, a differential-mode lightning strike occurs in the photovoltaic inverter 110, and the current of the first capacitor C1 begins to increase. At time T2, the current of the first capacitor C1 is greater than the first current threshold, and the controller 430 controls the inverter circuit 440 to stop working. Thus, before the current of the first inductor L1 increases, the controller 430 controls the switch tube in the inverter circuit 440 to be in the off state. The switch tube in the inverter circuit 440 is turned off when a small current flows through it, which can reduce the risk of failure of the switch tube in the inverter circuit 440 and improve the safety and reliability of the photovoltaic inverter 110.

[0088] Due to the electromagnetic induction phenomenon of the first inductor L1 (inverter inductor), there is a large delay in the current conversion of the first inductor L1. In the event of a differential-mode lightning strike on the photovoltaic inverter 110, the controller 114 controls the inverter circuit 112 to stop working according to the current of the first inductor L1, but will not be able to control the inverter circuit 112 to stop working in time, which will result in a high risk of damage to the photovoltaic inverter 110. In the photovoltaic inverter 400 provided in the embodiment of the present application, in the event of a differential-mode lightning strike on the photovoltaic inverter 400, the controller 430 controls the inverter circuit 440 to stop working according to the current of the three first capacitors C1. The current conversion delay of the three first capacitors C1 is smaller, so that the controller 430 can control the inverter circuit 440 to stop working in time, which can improve the safety and reliability of the photovoltaic inverter 400.

[0089] In one embodiment, Figure 6 On the basis of Figure 8 The figure shows a circuit topology diagram of another photovoltaic inverter 400 provided in an embodiment of the present application. The photovoltaic inverter 400 also includes three second inductors L2, which are respectively connected between the second ends of the three first inductors L1 and the three-phase AC port 420. The three second inductors L2 can be called port inductors.

[0090] The controller 430 is also used to detect the current of the three second inductors L2. When the current of at least one second inductor L2 is greater than the second current threshold, the inverter circuit 440 is controlled to stop working. The specific value of the second current threshold can be determined by the withstand voltage value or the withstand current value of the switching tube in the integrated inverter circuit 440. The embodiment of the present application does not limit the specific value of the second current threshold.

[0091] In one embodiment, the controller 430 can detect the current at one end where the three second inductors L2 are connected to the three first inductors L1, or can detect the current at one end where the three second inductors L2 are connected to the three-phase AC port 420. The location for detecting the current can be selected based on actual conditions. The embodiment of the present application does not limit the specific location for detecting the current.

[0092] In one embodiment, the controller 430 is further configured to control the inverter circuit 440 to stop operating if the average current of the at least one second inductor L2 exceeds a second current threshold within a preset time. The specific value of the preset time is not limited in this embodiment of the present application. This prevents the controller 430 from malfunctioning and causing the inverter circuit 440 to stop operating due to accidental fluctuations in the current of the at least one second inductor L2, thereby improving the reliability of the photovoltaic inverter 400.

[0093] Due to the electromagnetic induction phenomenon of the first inductor L1 (inverter inductor), there is a large delay in the current conversion of the first inductor L1. In the event of a differential-mode lightning strike on the photovoltaic inverter 110, the controller 114 controls the inverter circuit 112 to stop working according to the current of the first inductor L1, but will not be able to control the inverter circuit 112 to stop working in time, which will result in a high risk of damage to the photovoltaic inverter 110. In the photovoltaic inverter 400 provided in the embodiment of the present application, in the event of a differential-mode lightning strike on the photovoltaic inverter 400, the controller 430 controls the inverter circuit 440 to stop working according to the current of the three second inductors L2. The current conversion delay of the three second inductors L2 is smaller, so that the controller 430 can control the inverter circuit 440 to stop working in time, which can improve the safety and reliability of the photovoltaic inverter 400.

[0094] In one embodiment, Figure 8 On the basis of Figure 9 The figure shows a circuit topology diagram of another photovoltaic inverter 400 provided in an embodiment of the present application. The photovoltaic inverter 400 also includes three second capacitors C2. The first ends of the three second capacitors C2 are respectively connected to the first ends of the three second lightning arresters SPD2, and the second ends of the three second capacitors C2 are all used to connect to the ground terminal G. The three second capacitors C2 can be called port capacitors.

[0095] The controller 430 is also used to detect the current of the three second capacitors C2. When the current of at least one second capacitor C2 is greater than a third current threshold, the inverter circuit 440 is controlled to stop working. The specific value of the third current threshold can be determined by the withstand voltage value or the withstand current value of the switching tube in the integrated inverter circuit 440. The embodiment of the present application does not limit the specific value of the third current threshold.

[0096] In one embodiment, the controller 430 is further configured to control the inverter circuit 440 to stop operating if the average current of the at least one second capacitor C2 exceeds a third current threshold within a preset time. The specific value of the preset time is not limited in this embodiment. This prevents the controller 430 from malfunctioning and causing the inverter circuit 440 to stop operating due to accidental fluctuations in the current of the at least one second capacitor C2, thereby improving the reliability of the photovoltaic inverter 400.

[0097] Due to the electromagnetic induction phenomenon of the first inductor L1 (inverter inductor), there is a large delay in the current conversion of the first inductor L1. In the event of a differential-mode lightning strike on the photovoltaic inverter 110, the controller 114 controls the inverter circuit 112 to stop working according to the current of the first inductor L1, but will not be able to control the inverter circuit 112 to stop working in time, which will result in a high risk of damage to the photovoltaic inverter 110. In the photovoltaic inverter 400 provided in the embodiment of the present application, in the event of a differential-mode lightning strike on the photovoltaic inverter 400, the controller 430 controls the inverter circuit 440 to stop working according to the current of the three second capacitors C2. The current conversion delay of the three second capacitors C2 is smaller, so that the controller 430 can control the inverter circuit 440 to stop working in time, which can improve the safety and reliability of the photovoltaic inverter 400.

[0098] like Figure 10 As shown, an embodiment of the present application further provides a control method for a photovoltaic inverter, which is applied to the above-mentioned photovoltaic inverter 400. The method includes step S1001.

[0099] S1001: The controller 430 detects the voltage of the three-phase AC port 420. If the voltage of at least one phase of the AC port is greater than a voltage threshold, the controller 430 controls the inverter circuit 440 to stop operating. The specific value of the voltage threshold can be determined by the withstand voltage or current rating of the switching transistors in the inverter circuit 440. The specific value of the voltage threshold is not limited in this embodiment of the present application.

[0100] In one embodiment, the controller 430 may control the inverter circuit 440 to operate normally when the voltages of the three-phase AC port 420 are all less than or equal to the voltage threshold.

[0101] In one embodiment, the controller 430 controls the inverter circuit 440 to stop operating when the voltage of at least one AC port phase exceeds a voltage threshold. This includes controlling the inverter circuit 440 to stop operating when the average value of the voltage of at least one AC port phase exceeds the voltage threshold within a preset time. The specific value of the preset time is not limited in this embodiment of the present application. This prevents the controller 430 from erroneously controlling the inverter circuit 440 to stop operating when the voltage of at least one AC port phase fluctuates accidentally, thereby improving the reliability of the photovoltaic inverter 400.

[0102] Due to the electromagnetic induction phenomenon of the first inductor L1 (inverter inductor), there is a large delay in the current conversion of the first inductor L1. In the event of a differential-mode lightning strike on the photovoltaic inverter 110, the controller 114 controls the inverter circuit 112 to stop working based on the current of the first inductor L1. However, it will not be able to control the inverter circuit 112 to stop working in a timely manner, which will result in a high risk of damage to the photovoltaic inverter 110. In the control method of the photovoltaic inverter provided in the embodiment of the present application, in the event of a differential-mode lightning strike on the photovoltaic inverter 400, the controller 430 controls the inverter circuit 440 to stop working based on the voltage of the three-phase AC port 420. The voltage conversion delay of the three-phase AC port 420 is smaller, so that the controller 430 can control the inverter circuit 440 to stop working in a timely manner, which can improve the safety and reliability of the photovoltaic inverter 400.

[0103] In one embodiment, Figure 11 As shown, the photovoltaic inverter control method provided in the embodiment of the present application further includes step S1002 after the above step S1001.

[0104] S1002: When the time for which the inverter circuit 440 is stopped is greater than or equal to the time threshold, the controller 430 controls the inverter circuit 440 to resume normal operation. The embodiment of the present application does not limit the specific value of the time threshold.

[0105] The photovoltaic inverter control method provided in the embodiment of the present application can restore the working state of the photovoltaic inverter 400 in a timely manner, thereby improving the power supply continuity and reliability of the photovoltaic power generation system 500.

[0106] In one embodiment, reference Figure 6 ,like Figure 11 As shown, the control method of the photovoltaic inverter provided in the embodiment of the present application further includes step S1003. When executing step S1003, it can be executed simultaneously with the above-mentioned step S1001, and step S1002 can be executed after step S1003.

[0107] S1003: The controller 430 detects the currents of the three first capacitors C1. If the current of at least one of the first capacitors C1 exceeds a first current threshold, the controller 430 controls the inverter circuit 440 to stop operating. The specific value of the first current threshold may be determined by the withstand voltage or current rating of the switch in the inverter circuit 440. The embodiment of the present application does not limit the specific value of the first current threshold.

[0108] In one embodiment, the controller 430 may control the inverter circuit 440 to operate normally when the currents of the three first capacitors C1 are all less than or equal to the first current threshold.

[0109] In one embodiment, the controller 430 controls the inverter circuit 440 to stop operating when the current of at least one first capacitor C1 is greater than a first current threshold, including: the controller 430 controls the inverter circuit 440 to stop operating when the average value of the current of at least one first capacitor C1 is greater than the first current threshold within a preset time. The embodiment of the present application does not limit the specific value of the preset time. This can prevent the controller 430 from malfunctioning and causing the inverter circuit 440 to stop operating due to accidental fluctuations in the current of at least one first capacitor C1, thereby improving the reliability of the photovoltaic inverter 400.

[0110] Due to the electromagnetic induction phenomenon of the first inductor L1 (inverter inductor), there is a large delay in the current conversion of the first inductor L1. In the event of a differential-mode lightning strike on the photovoltaic inverter 110, the controller 114 controls the inverter circuit 112 to stop working according to the current of the first inductor L1. However, it will not be possible to control the inverter circuit 112 to stop working in time, which will result in a high risk of damage to the photovoltaic inverter 110. In the control method of the photovoltaic inverter provided in the embodiment of the present application, in the event of a differential-mode lightning strike on the photovoltaic inverter 400, the controller 430 controls the inverter circuit 440 to stop working according to the current of the three first capacitors C1. The current conversion delay of the three first capacitors C1 is smaller, so that the controller 430 can control the inverter circuit 440 to stop working in time, which can improve the safety and reliability of the photovoltaic inverter 400.

[0111] In one embodiment, reference Figure 8 ,like Figure 11 As shown, the control method of the photovoltaic inverter provided in the embodiment of the present application further includes step S1004. When executing step S1004, it can be executed simultaneously with the above-mentioned step S1001, and step S1002 can be executed after step S1004.

[0112] S1004: The controller 430 detects the currents of the three second inductors L2. If the current of at least one second inductor L2 exceeds a second current threshold, the controller 430 controls the inverter circuit 440 to stop operating. The specific value of the second current threshold can be determined by the withstand voltage or current rating of the switching transistors in the inverter circuit 440. The embodiment of the present application does not limit the specific value of the second current threshold.

[0113] In one embodiment, the controller 430 may control the inverter circuit 440 to operate normally when the currents of the three second inductors L2 are all less than or equal to the second current threshold.

[0114] In one embodiment, the controller 430 controls the inverter circuit 440 to stop operating when the current of the at least one second inductor L2 exceeds a second current threshold. This includes: the controller 430 controls the inverter circuit 440 to stop operating when the average value of the current of the at least one second inductor L2 exceeds the second current threshold within a preset time. The specific value of the preset time is not limited in this embodiment of the present application. This can prevent the controller 430 from erroneously controlling the inverter circuit 440 to stop operating when the current of the at least one second inductor L2 accidentally fluctuates, thereby improving the reliability of the photovoltaic inverter 400.

[0115] Due to the electromagnetic induction phenomenon of the first inductor L1 (inverter inductor), there is a large delay in the current conversion of the first inductor L1. In the event of a differential-mode lightning strike on the photovoltaic inverter 110, the controller 114 controls the inverter circuit 112 to stop working according to the current of the first inductor L1, but will not be able to control the inverter circuit 112 to stop working in time, which will result in a high risk of damage to the photovoltaic inverter 110. In the control method of the photovoltaic inverter provided in the embodiment of the present application, in the event of a differential-mode lightning strike on the photovoltaic inverter 400, the controller 430 controls the inverter circuit 440 to stop working according to the current of the three second inductors L2. The current conversion delay of the three second inductors L2 is smaller, so that the controller 430 can control the inverter circuit 440 to stop working in time, which can improve the safety and reliability of the photovoltaic inverter 400.

[0116] In one embodiment, reference Figure 9 ,like Figure 11 As shown, the control method of the photovoltaic inverter provided in the embodiment of the present application further includes step S1005. When executing step S1005, it can be executed simultaneously with the above-mentioned step S1001, and step S1002 can be executed after step S1005.

[0117] S1005: The controller 430 detects the currents of the three second capacitors C2. If the current of at least one of the second capacitors C2 exceeds a third current threshold, the controller 430 controls the inverter circuit 440 to stop operating. The specific value of the third current threshold may be determined by the withstand voltage or current rating of the switch in the inverter circuit 440. The embodiment of the present application does not limit the specific value of the third current threshold.

[0118] In one embodiment, the controller 430 may control the inverter circuit 440 to operate normally when the currents of the three second capacitors C2 are all less than or equal to the third current threshold.

[0119] In one embodiment, the controller 430 controls the inverter circuit 440 to stop operating when the current of at least one second capacitor C2 exceeds a third current threshold, including: controlling the inverter circuit 440 to stop operating when the average value of the current of at least one second capacitor C2 exceeds the third current threshold within a preset time. The specific value of the preset time is not limited in this embodiment of the present application. This can prevent the controller 430 from erroneously controlling the inverter circuit 440 to stop operating due to accidental fluctuations in the current of at least one second capacitor C2, thereby improving the reliability of the photovoltaic inverter 400.

[0120] Due to the electromagnetic induction phenomenon of the first inductor L1 (inverter inductor), there is a large delay in the current conversion of the first inductor L1. In the event of a differential-mode lightning strike on the photovoltaic inverter 110, the controller 114 controls the inverter circuit 112 to stop working according to the current of the first inductor L1. However, it will not be possible to control the inverter circuit 112 to stop working in a timely manner, which will result in a high risk of damage to the photovoltaic inverter 110. In the control method of the photovoltaic inverter provided in the embodiment of the present application, in the event of a differential-mode lightning strike on the photovoltaic inverter 400, the controller 430 controls the inverter circuit 440 to stop working according to the current of the three second capacitors C2. The current conversion delay of the three second capacitors C2 is smaller, so that the controller 430 can control the inverter circuit 440 to stop working in a timely manner, which can improve the safety and reliability of the photovoltaic inverter 400.

[0121] Based on this, Figure 5 As shown, the embodiment of the present application further provides a photovoltaic power generation system 500, which includes a photovoltaic inverter 400. The photovoltaic inverter 400 includes a DC port 410 and a three-phase AC port 420. The DC port 410 is used to connect to the output end of the photovoltaic array 200, and the three-phase AC port 420 is used to connect to the power grid or load 300. The circuit topology of the photovoltaic inverter 400 is as described above. Figure 5 、 Figure 6 、 Figure 8 or Figure 9The circuit topology of the photovoltaic inverter 400 shown in any of the figures.

[0122] The above detailed description of the photovoltaic inverter 400 and the analysis of its beneficial effects can be correspondingly referred to the control method of the photovoltaic inverter and the photovoltaic power generation system 500, and will not be repeated herein in the embodiments of the present application.

[0123] The above is only a specific embodiment of the present application, but the scope of protection of this application is not limited to this. Any changes or substitutions within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A photovoltaic inverter, characterized in that: The photovoltaic inverter includes a controller, a DC port, an inverter circuit, a first lightning arrester, three first inductors, three first capacitors, three second lightning arresters and a three-phase AC port, wherein the DC port is used to connect to the photovoltaic array, and the three-phase AC port is used to connect to the power grid or load; The input end of the inverter circuit is connected to the DC port, the three-phase output ends of the inverter circuit are respectively connected to the first ends of the three first inductors, the second ends of the three first inductors are respectively connected to the three-phase AC port, the first ends of the three first capacitors are respectively connected to the second ends of the three first inductors, the second ends of the three first capacitors are all used to connect to the ground end, the first ends of the three second lightning arresters are respectively connected to the three-phase AC port, the second ends of the three second lightning arresters are all connected to the first end of the first lightning arrester, and the second end of the first lightning arrester is used to connect to the ground end; The controller is used to detect the voltage of the three-phase AC port, and control the inverter circuit to stop working when the voltage of at least one phase of the AC port is greater than a voltage threshold.

2. The photovoltaic inverter according to claim 1, characterized in that: The controller is further configured to control the inverter circuit to stop operating when the average value of the voltage of at least one phase of the AC port is greater than the voltage threshold within a preset time.

3. The photovoltaic inverter according to claim 1 or 2, characterized in that: The controller is further configured to control the inverter circuit to resume normal operation when the time for controlling the inverter circuit to stop operating is greater than or equal to a time threshold.

4. A photovoltaic inverter, characterized in that: The photovoltaic inverter includes a controller, a DC port, an inverter circuit, a first lightning arrester, three first inductors, three first capacitors, three second lightning arresters and a three-phase AC port, wherein the DC port is used to connect to the photovoltaic array, and the three-phase AC port is used to connect to the power grid or load; The input end of the inverter circuit is connected to the DC port, the three-phase output ends of the inverter circuit are respectively connected to the first ends of the three first inductors, the second ends of the three first inductors are respectively connected to the three-phase AC port, the first ends of the three first capacitors are respectively connected to the second ends of the three first inductors, the second ends of the three first capacitors are all used to connect to the ground end, the first ends of the three second lightning arresters are respectively connected to the three-phase AC port, the second ends of the three second lightning arresters are all connected to the first end of the first lightning arrester, and the second end of the first lightning arrester is used to connect to the ground end; The controller is configured to detect the currents of the three first capacitors, and control the inverter circuit to stop operating when the current of at least one of the first capacitors is greater than a first current threshold.

5. The photovoltaic inverter according to claim 4, characterized in that: The controller is further configured to control the inverter circuit to stop operating when an average current of at least one of the first capacitors is greater than the first current threshold within a preset time.

6. The photovoltaic inverter according to claim 4 or 5, characterized in that: The controller is further configured to control the inverter circuit to resume normal operation when the time for controlling the inverter circuit to stop operating is greater than or equal to a time threshold.

7. A photovoltaic inverter, characterized in that: The photovoltaic inverter includes a controller, a DC port, an inverter circuit, a first lightning arrester, three first inductors, three first capacitors, three second lightning arresters, a three-phase AC port and three second inductors. The DC port is used to connect to the photovoltaic array, and the three-phase AC port is used to connect to the power grid or load. The input end of the inverter circuit is connected to the DC port, the three-phase output ends of the inverter circuit are respectively connected to the first ends of the three first inductors, the second ends of the three first inductors are respectively connected to the three-phase AC port, the first ends of the three first capacitors are respectively connected to the second ends of the three first inductors, the second ends of the three first capacitors are all used to connect to the ground end, the first ends of the three second lightning arresters are respectively connected to the three-phase AC port, the second ends of the three second lightning arresters are all connected to the first end of the first lightning arrester, the second end of the first lightning arrester is used to connect to the ground end, and the three second inductors are respectively connected between the second ends of the three first inductors and the three-phase AC port; The controller is configured to detect the currents of the three second inductors, and control the inverter circuit to stop operating when the current of at least one of the second inductors is greater than a second current threshold.

8. The photovoltaic inverter according to claim 7, characterized in that: The controller is further configured to control the inverter circuit to stop operating when an average value of the current of at least one of the second inductors is greater than the second current threshold within a preset time.

9. The photovoltaic inverter according to claim 7 or 8, characterized in that: The controller is further configured to control the inverter circuit to resume normal operation when the time for controlling the inverter circuit to stop operating is greater than or equal to a time threshold.

10. A photovoltaic inverter, characterized in that: The photovoltaic inverter includes a controller, a DC port, an inverter circuit, a first lightning arrester, three first inductors, three first capacitors, three second lightning arresters, a three-phase AC port, three second inductors and three second capacitors. The DC port is used to connect to the photovoltaic array, and the three-phase AC port is used to connect to the power grid or load. The input end of the inverter circuit is connected to the DC port, the three-phase output ends of the inverter circuit are respectively connected to the first ends of the three first inductors, the second ends of the three first inductors are respectively connected to the three-phase AC port, the first ends of the three first capacitors are respectively connected to the second ends of the three first inductors, the second ends of the three first capacitors are all used to connect to the ground end, the first ends of the three second lightning arresters are respectively connected to the three-phase AC port, the second ends of the three second lightning arresters are all connected to the first end of the first lightning arrester, the second end of the first lightning arrester is used to connect to the ground end, the three second inductors are respectively connected between the second ends of the three first inductors and the three-phase AC port, the first ends of the three second capacitors are respectively connected to the first ends of the three second lightning arresters, and the second ends of the three second capacitors are all used to connect to the ground end; The controller is configured to detect the currents of the three second capacitors, and control the inverter circuit to stop working when the current of at least one of the second capacitors is greater than a third current threshold.

11. The photovoltaic inverter according to claim 10, characterized in that: The controller is further configured to control the inverter circuit to stop operating when an average current of at least one of the second capacitors is greater than the third current threshold within a preset time.

12. The photovoltaic inverter according to claim 10 or 11, characterized in that: The controller is further configured to control the inverter circuit to resume normal operation when the time for controlling the inverter circuit to stop operating is greater than or equal to a time threshold.

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