Lightning protection circuit and power converter

Abstract

The utility model discloses a lightning protection circuit and a power converter, and relates to the technical field of power electronics. According to the lightning protection circuit, for the condition that a capacitor parallel branch in a bus capacitor circuit comprises a first capacitor, a second capacitor and an inductor, and the first capacitor is connected with the inductor in series and then connected with the second capacitor in parallel, a lightning protection device is arranged to be connected with the inductor in parallel; in the lightning stroke process, the voltage at the two ends of the inductor exceeds the action voltage of the lightning protection device, so that the lightning protection device is broken down, and the voltage at the two ends of the inductor is clamped at the voltage drop after the lightning protection device is broken down, so that overlarge voltage cannot be formed on the second capacitor; therefore, the problem of voltage oscillation caused by current backflow at the lightning stroke moment can be weakened, the voltage stress borne by a corresponding power device in a post-stage circuit is reduced, and the corresponding power device is effectively protected.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a lightning protection circuit and a power converter. Background Art

[0002] Because power converters need to filter ripples of different frequencies, their bus capacitance circuits typically require two different capacitors connected in parallel. For example, the bus capacitance circuit on the DC bus of a photovoltaic inverter is typically implemented by connecting an electrolytic capacitor and a film capacitor in parallel. Furthermore, to achieve decoupling of the different ripple absorption characteristics of the two capacitors, a corresponding inductor is often connected in series with the electrolytic capacitor, and this series branch is then connected in parallel with the film capacitor.

[0003] However, under this connection method, when the photovoltaic inverter needs to be protected against lightning, the presence of the inductor will affect the lightning current's return to the electrolytic capacitor, causing voltage oscillation in the parallel film capacitor. The oscillation process will cause excessive voltage stress on some power devices in the DC bus's downstream circuit, easily causing these power devices to fail due to overvoltage. Utility Model Content

[0004] In view of the above problems, the present application provides a lightning protection circuit and a power converter to reduce the voltage oscillation problem caused by current backflow during lightning strikes. The specific solution is as follows:

[0005] In a first aspect, the present application provides a lightning protection circuit connected to a busbar capacitor circuit of a power converter; the lightning protection circuit comprises: a lightning protection device; wherein,

[0006] The busbar capacitor circuit includes: a capacitor parallel branch; the capacitor parallel branch includes: a first capacitor, a second capacitor and an inductor; in the capacitor parallel branch, the first capacitor and the inductor are connected in series, and the series branch is connected in parallel with the second capacitor;

[0007] The lightning protection device is connected in parallel with the inductor.

[0008] In one possible implementation, the lightning protection device includes any one of the following:

[0009] Varistor;

[0010] Gas discharge tubes;

[0011] TVS diodes.

[0012] In a possible implementation, the number of the capacitor parallel branches in the bus capacitor circuit is greater than 1;

[0013] The number of the lightning protection devices in the lightning protection circuit is greater than 1;

[0014] Each of the lightning protection devices is connected in parallel with the inductor in the corresponding capacitor parallel branch.

[0015] A second aspect of the present application provides a power converter, comprising: a main circuit, a bus capacitor circuit, and a lightning protection circuit as described in the first aspect or any implementation form of the first aspect; wherein,

[0016] The bus capacitor circuit is connected between the positive and negative poles of the DC bus of the main circuit;

[0017] The busbar capacitor circuit includes: a capacitor parallel branch; the capacitor parallel branch includes: a first capacitor, a second capacitor and an inductor; in the capacitor parallel branch, the first capacitor and the inductor are connected in series, and the series branch is connected in parallel with the second capacitor;

[0018] The lightning protection circuit is connected to the busbar capacitor circuit.

[0019] In a possible implementation, the first capacitor is an electrolytic capacitor.

[0020] In a possible implementation, the second capacitor is a thin film capacitor.

[0021] In a possible implementation, the number of the capacitor parallel branches in the bus capacitor circuit is 2;

[0022] The two capacitor parallel branches are connected in series between the positive and negative poles of the DC bus;

[0023] The series connection point of the two parallel capacitor branches serves as the midpoint of the DC bus.

[0024] In one possible implementation, the main circuit includes: a DC / AC conversion circuit;

[0025] The DC side of the DC / AC conversion circuit is connected to the DC bus;

[0026] The AC side of the DC / AC conversion circuit serves as the AC side of the power converter.

[0027] In a possible implementation, the DC / AC conversion circuit includes: at least one phase bridge arm;

[0028] The DC side of the bridge arm is connected to the DC side of the DC / AC conversion circuit;

[0029] The AC side of the bridge arm is connected to one phase of the AC side of the DC / AC conversion circuit.

[0030] In a possible implementation, the bridge arm is a T-shaped midpoint clamped topology.

[0031] In a possible implementation, the main circuit further includes: at least one DC / DC conversion circuit;

[0032] One side of the DC / DC conversion circuit serves as a DC side interface of the power converter;

[0033] The other side of the DC / DC conversion circuit is connected to the DC bus.

[0034] By means of the above-mentioned technical solution, the lightning protection circuit provided by the present application, for the case where the capacitor parallel branch in the bus capacitor circuit includes a first capacitor, a second capacitor and an inductor, and the first capacitor is connected in series with the inductor and then connected in parallel with the second capacitor, a lightning protection device is set to be connected in parallel with the inductor; during a lightning strike, the voltage across the inductor exceeds the operating voltage of the lightning protection device, causing the lightning protection device to be broken down, and the voltage across the inductor is clamped at the voltage drop after the lightning protection device is broken down, so that no excessive voltage will be formed on the second capacitor; thereby, the voltage oscillation problem caused by the current backflow at the moment of lightning strike can be weakened, the voltage stress borne by the corresponding power devices in the subsequent circuit can be reduced, and the corresponding power devices can be effectively protected. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and other features, advantages, and aspects of the various embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and that the originals and elements are not necessarily drawn to scale.

[0036] Figure 1 A schematic diagram of the connection relationship between a lightning protection circuit and a busbar capacitor circuit provided in an embodiment of the present application;

[0037] Figure 2 A schematic diagram of the structure of a lightning protection circuit provided in an embodiment of the present application;

[0038] Figure 3 Another structural diagram of a lightning protection circuit provided in an embodiment of the present application;

[0039] Figure 4 Another structural diagram of a lightning protection circuit provided in an embodiment of the present application;

[0040] Figure 5 A schematic diagram of the connection relationship between the lightning protection circuit provided in an embodiment of the present application and a bus capacitor circuit in another structure;

[0041] Figure 6 A schematic diagram of the structure of a bus capacitor circuit at the DC bus of a photovoltaic inverter provided by the prior art;

[0042] Figure 7A schematic diagram of the structure of a power converter with a T-shaped midpoint clamp topology and a lightning protection circuit added thereto provided by an embodiment of the present application;

[0043] Figure 8 A schematic diagram of the structure of a power converter provided in an embodiment of the present application;

[0044] Figure 9 A schematic diagram of a specific structure of a power converter provided in an embodiment of the present application using a T-shaped midpoint clamped topology;

[0045] Figure 10 A schematic diagram of the structure of an NPC topology that can be used in a power converter provided in an embodiment of the present application;

[0046] Figure 11 A schematic diagram of the structure of an ANPC topology that can be used in a power converter provided in an embodiment of the present application;

[0047] Figure 12 Another structural schematic diagram of a power converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0048] The following describes the embodiments of the present application in conjunction with the accompanying drawings. The terms used in the implementation methods of the present application are only used to explain the specific embodiments of the present application and are not intended to limit the present application.

[0049] The embodiments of the present application are described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. It is known to those of ordinary skill in the art that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0050] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, and this is merely a way of distinguishing the objects of the same attributes when describing them in the embodiments of the present application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment comprising a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0051] This application provides a lightning protection circuit to reduce the voltage oscillation problem caused by current backflow during lightning strikes. The specific solution is as follows:

[0052] See also Figure 1 The lightning protection circuit 20 is connected to the bus capacitor circuit 10 of the power converter; the lightning protection circuit 20 includes: SPD (Surge Protective Device, lightning protection device) 201; wherein:

[0053] The busbar capacitor circuit 10 includes: a capacitor parallel branch 101; the capacitor parallel branch 101 includes: a first capacitor C1, a second capacitor C2 and an inductor L; in the capacitor parallel branch 101, the first capacitor C1 is connected in series with the inductor L, and the series connection branch is connected in parallel with the second capacitor C2.

[0054] The SPD 201 is connected to the inductor L in parallel.

[0055] The specific working principle is:

[0056] When a lightning strike test is performed, or when a lightning strike actually occurs, a lightning current will flow in the busbar capacitor circuit 10. When the lightning current flows through the inductor L, causing the voltage across the inductor L to exceed the operating voltage of the SPD 201, the SPD 201 will be broken down. Since the voltage drop of the SPD 201 after the breakdown is very small, the voltage across the inductor L can be clamped to a smaller value, thereby preventing a large voltage from being superimposed on the second capacitor C2. In other words, the voltage of the second capacitor C2 will not be too high, thereby reducing the voltage oscillation problem caused by the current backflow at the time of the lightning strike.

[0057] In practical applications, the SPD 201 may be a varistor, such as Figure 2 Alternatively, the SPD 201 may also be a gas discharge tube, such as Figure 3 Alternatively, the SPD 201 may also be a GDT (Gas Discharge Tubes, ceramic gas discharge tube) as shown in FIG. Figure 4 The TVS (Transient Voltage Suppressors) shown in FIG are merely examples and are not intended to be limiting. Any device capable of achieving the aforementioned voltage clamping function is within the scope of protection of this application. Furthermore, the specific device parameters of SPD 201 can also be configured based on actual lightning protection requirements and are not limited here.

[0058] The lightning protection circuit 20 provided in this embodiment is configured such that, for a case where the capacitor parallel branch 101 in the busbar capacitor circuit 10 includes a first capacitor C1, a second capacitor C2, and an inductor L, and the first capacitor C1 is connected in series with the inductor L and then connected in parallel with the second capacitor C2, an SPD 201 is connected in parallel with the inductor L. During a lightning strike, the voltage across the inductor L exceeds the operating voltage of the SPD 201, causing the SPD 201 to break down. The voltage across the inductor L is clamped to the voltage drop after the breakdown of the SPD 201, thereby preventing an excessive voltage from being formed on the second capacitor C2. Thus, the voltage oscillation problem caused by current backflow at the time of lightning strike can be reduced, the voltage stress borne by the corresponding power devices in the subsequent circuit can be reduced, and the corresponding power devices can be effectively protected.

[0059] It is worth noting that, in actual applications, the number of capacitor parallel branches 101 in the bus capacitor circuit 10 is not limited to 1, for example, its number can also be greater than 1; in this case, the number of SPDs 201 in the lightning protection circuit 20 is also greater than 1, and each SPD 201 is respectively connected in parallel with the inductor L in the corresponding capacitor parallel branch 101.

[0060] This embodiment provides a common structure of the lightning protection circuit 20 based on the previous embodiment. Figure 5 The number of the capacitor parallel branches 101 in the busbar capacitor circuit 10 is 2, the number of the SPDs 201 in the lightning protection circuit 20 is also 2, and the inductor L in each capacitor parallel branch 101 is connected in parallel with a corresponding SPD 201.

[0061] See also Figure 6 Conventional photovoltaic inverters are provided with: positive half-bus capacitors and negative half-bus capacitors between the positive BUS+ and negative BUS- poles of their DC bus. The positive half-bus capacitors are connected between the positive BUS+ and midpoint BUS-N of the DC bus, and the negative half-bus capacitors are connected between the midpoint BUS-N and negative BUS- of the DC bus. The positive half-bus capacitors are formed by connecting an electrolytic capacitor C11 and an inductor L01 in series and then connecting them in parallel with a film capacitor C21, and the negative half-bus capacitors are formed by connecting an electrolytic capacitor C12 and an inductor L02 in series and then connecting them in parallel with a film capacitor C22. The DC bus is provided with an inverter circuit at the rear stage, which can be used. Figure 6 The T-shaped midpoint clamped topology shown in FIG. 1 includes an upper tube Q1, a lower tube Q4, and two cross tubes Q2 and Q3.

[0062] for Figure 6In the structure shown, when a lightning strike occurs, for the positive half-bus capacitor, the inductor L01 connected in series with the electrolytic capacitor C11 will affect the lightning current flowing back to the electrolytic capacitor C11, which in turn causes voltage oscillations in the film capacitor C21. This oscillation process will cause the voltage on the film capacitor C21 to be too high, causing excessive voltage stress on the cross-connectors Q2 and Q3 in the subsequent inverter circuit. For the negative half-bus capacitor, the inductor L02 connected in series with the electrolytic capacitor C12 will affect the lightning current flowing back to the electrolytic capacitor C12, which in turn causes voltage oscillations in the film capacitor C22. This oscillation process will cause the voltage on the film capacitor C22 to be too high, causing excessive voltage stress on the cross-connectors Q2 and Q3 in the subsequent inverter circuit. Therefore, it is easy to cause overvoltage failure of the cross-connectors Q2 and Q3 in the subsequent inverter circuit.

[0063] The lightning protection circuit 20 provided in this embodiment is configured such that each inductor L in the capacitor parallel branch 101 is respectively connected in parallel with a corresponding SPD 201. During a lightning strike, when the voltage across any inductor L exceeds the operating voltage of the SPD 201 to which it is connected in parallel, the corresponding SPD 201 will be broken down, and the voltage across the inductor L will be clamped to the voltage drop after the breakdown of the SPD 201 to which it is connected in parallel. This prevents an excessive voltage from being generated on the second capacitor C2 in the same capacitor parallel branch 101. Thus, the voltage oscillation problem caused by current backflow at the time of lightning strike can be reduced, and the voltage stress on the cross-connectors Q2 and Q3 in the subsequent inverter circuit can be reduced, thereby effectively protecting the cross-connectors Q2 and Q3 in the subsequent inverter circuit.

[0064] compared to Figure 6 and Figure 7 In the circuit structure shown, this embodiment introduces two SPDs 201 to effectively reduce the oscillation of the half-bus voltage during a lightning strike, thereby solving the problem of damage to the downstream inverter circuit caused by excessive voltage stress on the cross-tubes Q2 and Q3 due to excessive half-bus voltage, thereby improving the stability of the system and having high application value.

[0065] In actual applications, the position of the bus capacitor circuit 10 in the power converter is not limited, and when the number of capacitor parallel branches 101 in the bus capacitor circuit 10 is greater than 1, the connection relationship of each capacitor parallel branch 101 can be series, parallel, or both series and parallel. This is not limited here and can be determined according to the specific application environment. As long as the inductor L in each capacitor parallel branch 101 is respectively connected in parallel with the corresponding SPD 201, it is within the protection scope of this application.

[0066] In addition, the SPD 201 connected in parallel to each inductor L can be an MOV, GDT or TVS, etc., which is not limited here; the SPDs 201 connected in parallel to different inductors L can be the same device or different devices, as long as they can achieve the above-mentioned voltage clamping function, they are all within the protection scope of this application.

[0067] Another embodiment of the present application further provides a power converter, such as Figure 8 As shown in , it includes: a main circuit, a busbar capacitor circuit 10 and a lightning protection circuit 20 as described in any of the above embodiments; wherein:

[0068] The bus capacitor circuit 10 is connected between the positive electrode BUS+ and the negative electrode BUS- of the DC bus of the main circuit.

[0069] In one example, the main circuit may include a DC / AC conversion circuit 31; the DC side of the DC / AC conversion circuit 31 is connected to a DC bus; and the AC side of the DC / AC conversion circuit 31 serves as the AC side of the power converter. In this case, the power converter may serve as a photovoltaic inverter or an energy storage converter, etc., without limitation herein.

[0070] The busbar capacitor circuit 10 includes: a capacitor parallel branch 101; the capacitor parallel branch 101 includes: a first capacitor C1, a second capacitor C2 and an inductor L; in the capacitor parallel branch 101, the first capacitor C1 is connected in series with the inductor L, and the series connection branch is connected in parallel with the second capacitor C2.

[0071] In practical applications, the power converter may contain ripples of different frequencies that need to be filtered. For example, photovoltaic inverters often have high-frequency ripples of around 20kHz and power-frequency ripples of around 50Hz. Film capacitors have a smaller capacity and can be used to filter high-frequency ripples, while electrolytic capacitors have a larger capacity and can be used to filter power-frequency ripples. Therefore, the first capacitor C1 can be set as an electrolytic capacitor, such as an aluminum electrolytic capacitor, and the second capacitor C2 can be set as a film capacitor. The presence of the inductor L allows the two capacitors to absorb the corresponding ripples respectively, achieving decoupling of the absorption of the two capacitors for ripples of different frequencies.

[0072] The lightning protection circuit 20 is connected to the busbar capacitor circuit 10. The specific structure and working principle of the lightning protection circuit 20 can be found in the above embodiment, and will not be described in detail here.

[0073] The power converter provided in this embodiment adopts the lightning protection circuit 20 and connects a corresponding SPD 201 in parallel with the inductor L. When the voltage across the inductor L exceeds the operating voltage of the SPD 201 during a lightning strike, the voltage across the inductor L can be limited to a smaller value. In this way, a large voltage is not superimposed on the second capacitor C2, thereby effectively protecting the power devices in the subsequent circuit.

[0074] Based on the above embodiment, this embodiment provides some specific examples for the structure of the power converter, such as:

[0075] In one example, the DC / AC conversion circuit 31 may include at least one-phase bridge arm 301, the DC side of the bridge arm 301 is connected to the DC side of the DC / AC conversion circuit 31; the AC side of the bridge arm 301 is connected to one phase of the AC side of the DC / AC conversion circuit 31. Figure 7 Only one-phase bridge arm 301 of the DC / AC conversion circuit 31 is shown. For a three-phase system, the DC / AC conversion circuit 31 may include three-phase bridge arms 301, such as Figure 9 As shown in .

[0076] In practical applications, the specific structure of the bridge arm 301 in the DC / AC conversion circuit 31 is not limited, and various topologies in the prior art can be adopted, such as various two-level topologies, or three-level topologies such as a mid-point clamped topology; the specific structure of the mid-point clamped topology can be a T-type or an I-type, wherein, Figure 7 and Figure 9 The 301 in the figure shows a T-shaped midpoint clamp topology. Figure 10 and Figure 11 The topologies shown are all I-shaped midpoint clamped. Figure 10 The figure shows the NPC (Neutral Point Clamped) topology. Figure 11 The figure shows an ANPC (Active Neutral Point Clamped) topology. The specific topology of the DC / AC conversion circuit 31 can be determined according to the actual application environment, and various structures in the prior art are within the scope of protection of this application. In addition, the power devices in the DC / AC conversion circuit 31 can be IGBTs (Insulated Gate Bipolar Transistors) or MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), etc., which are not specifically limited here.

[0077] by Figure 7 or Figure 9 The T-shaped midpoint clamped topology shown is used as an example for demonstration. Its internal power devices include switch tubes Q1 to Q4, wherein the positive pole BUS+ of the DC bus is connected to the negative pole BUS- of the DC bus through the switch tubes Q1 and Q4 in sequence. The connection point of the switch tubes Q1 and Q4 serves as the AC side of the T-shaped midpoint clamped topology. The AC side of the T-shaped midpoint clamped topology is also connected to the midpoint BUS-N of the DC bus through the switch tubes Q2 and Q3 in sequence; the switch tubes Q2 and Q3 are also the cross tubes in the corresponding bridge arm 301.

[0078] In practical applications, such as Figure 7 or Figure 9 As shown in , the number of capacitor parallel branches 101 in the bus capacitor circuit 10 can be 2; the two capacitor parallel branches 101 are connected in series between the positive electrode BUS+ and the negative electrode BUS- of the DC bus; the series connection point of the two capacitor parallel branches 101 serves as the midpoint BUS-N of the DC bus, providing a connection point for the midpoint BUS-N of the DC bus when the DC / AC conversion circuit 31 adopts a midpoint clamped topology.

[0079] In addition, if Figure 7 or Figure 9 As shown in , the DC / AC conversion circuit 31 may further include a filter inductor arranged on the AC side of each phase bridge arm 301, and a filter capacitor on the other side of the filter inductor of each phase, and the other side of the filter capacitor of each phase may be connected to the midpoint BUS-N of the DC bus.

[0080] Figure 12 Another structural example of this power converter is provided. Based on the above embodiment, the main circuit further includes: at least one DC / DC conversion circuit 32; one side of the DC / DC conversion circuit 32 serves as a DC-side interface for the power converter; and the other side of the DC / DC conversion circuit 32 is connected to the DC bus. In this case, the power converter can be used as a string photovoltaic inverter.

[0081] Figure 12 The busbar capacitor circuit 10 and the lightning protection circuit 20 are shown based on Figure 8 In practical applications, the two can also be multiple, such as using Figure 7 or Figure 9 The form shown in ; it is not limited here, and it depends on its specific application environment, and all are within the scope of protection of this application.

[0082] The same or similar parts between the various embodiments in this specification can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Ordinary technicians in this field can understand and implement it without making any creative efforts.

[0083] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0084] With respect to the above description of the disclosed embodiments, the features described in the various embodiments in this specification may be interchanged or combined to enable those skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A lightning protection circuit, characterized in that: A bus capacitor circuit connected to the power converter; The lightning protection circuit includes: a lightning protection device; wherein, The busbar capacitor circuit includes: a capacitor parallel branch; the capacitor parallel branch includes: a first capacitor, a second capacitor and an inductor; in the capacitor parallel branch, the first capacitor and the inductor are connected in series, and the series branch is connected in parallel with the second capacitor; The lightning protection device is connected in parallel with the inductor.

2. The lightning protection circuit according to claim 1, characterized in that: The lightning protection device includes any one of the following: Varistor; Gas discharge tubes; TVS diodes.

3. The lightning protection circuit according to claim 1 or 2, characterized in that: The number of the capacitor parallel branches in the bus capacitor circuit is greater than 1; The number of the lightning protection devices in the lightning protection circuit is greater than 1; Each of the lightning protection devices is connected in parallel with the inductor in the corresponding capacitor parallel branch.

4. A power converter, characterized in that: include: A main circuit, a busbar capacitor circuit, and a lightning protection circuit as claimed in any one of claims 1 to 3; wherein, The bus capacitor circuit is connected between the positive and negative poles of the DC bus of the main circuit; The busbar capacitor circuit includes: a capacitor parallel branch; the capacitor parallel branch includes: a first capacitor, a second capacitor and an inductor; in the capacitor parallel branch, the first capacitor and the inductor are connected in series, and the series branch is connected in parallel with the second capacitor; The lightning protection circuit is connected to the busbar capacitor circuit.

5. The power converter according to claim 4, characterized in that The first capacitor is an electrolytic capacitor.

6. The power converter according to claim 4, characterized in that The second capacitor is a thin film capacitor.

7. The power converter according to claim 4, wherein: The number of the capacitor parallel branches in the bus capacitor circuit is 2; The two capacitor parallel branches are connected in series between the positive and negative poles of the DC bus; The series connection point of the two parallel capacitor branches serves as the midpoint of the DC bus.

8. The power converter according to any one of claims 4 to 7, characterized in that: The main circuit includes: a DC / AC conversion circuit; The DC side of the DC / AC conversion circuit is connected to the DC bus; The AC side of the DC / AC conversion circuit serves as the AC side of the power converter.

9. The power converter according to claim 8, characterized in that The DC / AC conversion circuit includes: at least one phase bridge arm; The DC side of the bridge arm is connected to the DC side of the DC / AC conversion circuit; The AC side of the bridge arm is connected to one phase of the AC side of the DC / AC conversion circuit.

10. The power converter according to claim 9, characterized in that The bridge arm is a T-shaped midpoint clamped topology.

11. The power converter according to claim 8, wherein: The main circuit also includes: at least one DC / DC conversion circuit; One side of the DC / DC conversion circuit serves as a DC side interface of the power converter; The other side of the DC / DC conversion circuit is connected to the DC bus.

Images