EMI filter module, EMI filter circuit, and photovoltaic inverter

Abstract

The utility model relates to an EMI filter module, an EMI filter circuit, and a photovoltaic inverter, wherein the EMI filter module includes a base plate, at least two EMI filter units arranged on the base plate, each EMI filter unit includes a cable connector, at least two safety capacitor groups, the at least two safety capacitor groups are electrically connected to the cable connector, and a through hole for passing a PV harness is provided on the base plate corresponding to each safety capacitor group, and the EMI filter circuit is used to perform EMI filtering on several PV output harnesses of a photovoltaic system, each PV output harness includes a PV+ harness and a PV‑ harness, wherein the EMI filter circuit includes the EMI filter module as described above, each PV+ harness in the several PV output harnesses is connected to an EMI filter unit, and each PV‑ harness is connected to another EMI filter unit. The present application simplifies the structure of the EMI filter module, occupies a small volume, and is convenient for wiring, thereby achieving the purpose of reducing production costs and assembly costs.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaic power generation equipment, and in particular to an EMI filter module and an EMI filter circuit used for filtering a photovoltaic PV interface, and a photovoltaic inverter with the EMI filter circuit. Background Art

[0002] High-power grid-connected inverters (for example, for wind power generation and photovoltaic power generation systems) can gradually solve energy shortages and environmental pollution. However, high-power grid-connected inverters will generate a lot of electromagnetic interference (EMI, which is electronic noise that interferes with cable signals and reduces signal integrity) during grid-connected applications, and solar cell strings will also introduce differential mode noise and common mode noise into the inverter.

[0003] In order to solve this problem, high-power grid-connected inverters are usually equipped with EMI filters on the DC input side. A filter unit of the EMI filter may include passive filter components such as X capacitors, Y capacitors, differential mode inductors, common mode inductors, and resistors.

[0004] One of the prior arts uses a packaged integrated EMI filter, such as the prior application entitled "A passive component integrated device suitable for a single-phase full-bridge inverter with an LC harmonic filter and an EMI filter" and publication number CN115705952A, which can improve power density and reduce the space occupied by passive filter components, but still has the following disadvantages:

[0005] (1) It requires a larger metal casing and potting compound, so the cost is higher;

[0006] (2) It is not easy to replace the components. If only one resistor is damaged, the entire resistor must be replaced, which is costly.

[0007] (3) The inverter with standard configuration (DC filter grounding or AC filter grounding has been done before leaving the factory) may not work properly during on-site operation, and it is inconvenient to adjust the grounding wire;

[0008] (4) The packaged filter is large in size and requires a large installation space.

[0009] Therefore, how to optimize the structure of the EMI filter unit to overcome the above-mentioned defects is the technical problem that this application aims to solve. Utility Model Content

[0010] A main purpose of the present utility model is to overcome at least one of the above-mentioned defects, and to provide an EMI filter module, an EMI filter circuit, and a photovoltaic inverter, which simplify the structure of the EMI filter module, occupy a small volume, and are easy to wire, thereby achieving the purpose of reducing production costs and assembly costs.

[0011] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0012] The utility model provides an EMI filter module, which comprises a base plate and at least two EMI filter units arranged on the base plate, wherein:

[0013] Each EMI filtering unit includes a cable connector and at least two safety capacitor groups, the at least two safety capacitor groups are electrically connected to the cable connector, and a through hole for passing a PV harness is opened on the bottom plate corresponding to each safety capacitor group.

[0014] According to one embodiment of the present invention, the safety capacitor group includes a first safety capacitor Cx, one end of the first safety capacitor Cx is connected to the cable connector, and the other end of the first safety capacitor Cx is connected to the cable connector in another EMI filter unit.

[0015] According to one embodiment of the present invention, the safety capacitor group includes a second safety capacitor Cy, one end of the second safety capacitor Cy is connected to the cable connector, and the other end is grounded.

[0016] In particular, the utility model also provides an EMI filtering circuit for performing EMI filtering on several PV output harnesses of a photovoltaic system, each PV output harness including a PV+ harness and a PV- harness, wherein the EMI filtering circuit includes the EMI filtering module as described above, each PV+ harness in the several PV output harnesses is connected to an EMI filtering unit, and each PV- harness is connected to another EMI filtering unit.

[0017] According to one embodiment of the utility model, the EMI filtering circuit includes multiple connecting terminals, and each PV+ harness or each PV- harness connected to the same EMI filtering unit is connected to a connecting terminal, and the connecting terminal is electrically connected to the cable connector in the EMI filtering unit.

[0018] According to one embodiment of the present invention, the photovoltaic system includes a plurality of solar cell strings and a plurality of solar controllers, each solar cell string has a PV output harness, each solar cell string is connected to a solar controller through the PV output harness, each solar controller is connected to a plurality of solar cell strings, and in the PV output harnesses of the plurality of solar cell strings connected to the same solar controller, each PV+ harness is connected to an EMI filter unit, and each PV- harness is connected to another EMI filter unit.

[0019] According to one of the embodiments of the utility model, the PV output harnesses of multiple solar cell strings connected to the same solar controller are combined and divided into at least two lead-out wires after combination. The at least two lead-out wires are respectively connected to two EMI filter units according to the positive and negative electrical polarities.

[0020] According to one embodiment of the present invention, PV output harnesses of a plurality of solar cell strings connected to the same solar controller are combined through a trip switch, and the EMI filter module is disposed at the rear end of the trip switch.

[0021] In particular, the utility model also provides a photovoltaic inverter, which includes the EMI filter circuit as described above.

[0022] Compared with the prior art, the advantages and beneficial effects of the EMI filter module, EMI filter circuit, and photovoltaic inverter of the utility model patent application are:

[0023] The present application optimizes the structure of the EMI filter module, making it easier to thread and fix the wiring harness when arranging the EMI filter circuit, thereby achieving the purpose of simplifying the connection and installation method of the output harness of the solar cell string with the EMI filter board, thereby reducing production and assembly costs, and also enabling the cost of the photovoltaic inverter with the EMI filter circuit to be reduced accordingly. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0025] Figure 1 It is a schematic diagram of electrical connection between a photovoltaic inverter and a PV output harness according to an embodiment of the utility model;

[0026] Figure 2 It is a schematic diagram of electrical connection between a photovoltaic inverter and a solar cell string according to an embodiment of the utility model;

[0027] Figure 3 It is a structural schematic diagram of an EMI filter module according to an embodiment of the utility model;

[0028] Figure 4 It is a schematic diagram of the connection between an EMI filter unit and a PV output harness in an EMI filter module according to an embodiment of the utility model;

[0029] Figure 5 It is a schematic diagram of electrical connection between a photovoltaic inverter and a solar cell string according to another embodiment of the utility model.

[0030] The reference numerals are as follows:

[0031] 1. Bottom plate;

[0032] 2. EMI filter unit, 21. first EMI filter unit, 22. second EMI filter unit, 23. third EMI filter unit;

[0033] 3. Cable connector;

[0034] 4. Safety capacitor group, 41. first safety capacitor Cx, 42. second safety capacitor Cy;

[0035] 5. Through hole;

[0036] 6. Connect the terminals. DETAILED DESCRIPTION

[0037] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0038] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] When different solar cell strings are connected to the inverter via the PV output harness, EMI filtering can be set at the front end of the inverter, or the EMI filtering can be set inside the inverter.

[0040] like Figure 1As shown, the EMI filter module is set in the inverter, and the PV output harness of each solar cell string includes a PV+ harness and a PV- harness. The PV output harness is sent to the trip switch after EMI filtering to be merged into an MPPT combined harness to connect other functional components of the inverter, or the PV output harness is merged into an MPPT combined harness through the trip switch and then EMI filtered and then connected to other functional components of the inverter, or the PV output harness is not merged and does not constitute an MPPT combined harness and is directly processed as a PV output harness.

[0041] The electrical schematic diagram of the EMI filter module filtering photovoltaic PV is as follows Figure 2 As shown, Figure 2 The dotted box in the figure is a schematic diagram of the capacitor setting of the EMI filter module. The DC input of the DC side of the photovoltaic inverter is connected to the PV+ harness and the PV- harness, and safety capacitors Cx and Cy are installed between the PV+ harness, the PV- harness and the DC side of the DC / AC inverter module. A safety capacitor Cy is connected between the PV+ harness and the PE line, another safety capacitor Cy is connected between the PV- harness and the PE line, and a safety capacitor Cx is connected between the PV+ harness and the PV- harness.

[0042] Embodiment 1:

[0043] This embodiment describes an EMI filtering module, such as Figure 3 As shown, it includes a base plate 1 and at least two EMI filter units 2 arranged on the base plate 1, wherein:

[0044] Each EMI filtering unit 2 includes a cable connector 3 and at least two safety capacitor groups 4. The at least two safety capacitor groups 4 are electrically connected to the cable connector 3. Corresponding to each safety capacitor group 4, a through hole 5 for passing the PV wiring harness is opened on the base plate 1.

[0045] The safety capacitor group 4 includes a first safety capacitor Cx41 and a second safety capacitor Cy42, wherein:

[0046] One end of the first safety capacitor Cx41 is connected to the cable connector 3, and the other end is connected to the cable connector 3 in another EMI filter unit 2;

[0047] One end of the second safety capacitor Cy42 is connected to the cable connector 3 , and the other end is grounded or connected to the PE line.

[0048] In addition, based on design requirements, the type or number of safety capacitors in the safety capacitor group 4 can also be adjusted. For example, if only phase-to-phase filtering design is required during EMI filtering, only the first safety capacitor Cx is designed in the safety capacitor group 4, and the number of the first safety capacitor Cx is designed with different capacitance values ​​and different numbers according to the filtering design requirements, and the second safety capacitor Cy can be designed in the circuit of the subsequent stage. Similarly, if only filtering design between the meeting PE is required during EMI filtering, only the second safety capacitor Cy is designed in the safety capacitor group 4, and the number of the second safety capacitor Cy is designed with different capacitance values ​​and different numbers according to the filtering design requirements, and the first safety capacitor Cx can be designed in the circuit of the subsequent stage.

[0049] In this embodiment, three EMI filter units 2 are arranged on the bottom plate 1, wherein the first EMI filter unit 21 includes four safety capacitor groups 4, and the second EMI filter unit 22 and the third EMI filter unit 23 are respectively provided with two safety capacitor groups 4. For example, for a photovoltaic system with four solar cell strings, each PV+ harness in the four PV output harnesses is respectively connected to the four safety capacitor groups 4 in the first EMI filter unit 21, and the other PV- harnesses are connected to the safety capacitor groups 4 of the second EMI filter unit 22 and the third EMI filter unit 23.

[0050] As for the number of safety capacitor groups 4 in each EMI filter unit 2, it can be adjusted according to the working conditions. For example, in the above embodiment, the second EMI filter unit 22 and the third filter unit can be combined to form a structure like the first EMI filter unit 21, or the first EMI filter unit 21 can be split into a structure like the second EMI filter unit 22 and the third filter unit. Generally speaking, since the PV output harness of each solar cell module has two harnesses, one positive and one negative, that is, the PV+ harness and the PV- harness, the total number of safety capacitor groups 4 in the EMI filter unit 2 selected to be connected to the PV+ harness or the PV- harness respectively must meet the design requirements.

[0051] In one embodiment, taking the wiring and electrical connection structure of the second EMI filter unit 22 as an example, the second EMI filter unit 22 is provided with a connection structure of two PV-wiring harnesses as shown in FIG. Figure 4 As shown, the PV- harnesses of two different solar cell strings pass through the through holes 5 corresponding to the two safety capacitor groups 4, and the two PV- harnesses are connected to the same connection terminal 6, which is then connected to the cable connector 3 of the second EMI filter unit 22, so that the two PV- harnesses are electrically connected to the safety capacitor group 4. Combined with the connection of the PV+ harness at the first EMI filter unit 21, the electrical connection of the EMI filtering of each solar cell string is completed.

[0052] Embodiment 2:

[0053] This embodiment describes an EMI filtering circuit for performing EMI filtering on several PV output harnesses of a photovoltaic system, wherein each PV output harness includes a PV+ harness and a PV- harness, wherein the EMI filtering circuit includes the EMI filtering module as described in Embodiment 1, and each PV+ harness among the several PV output harnesses is connected to an EMI filtering unit 2, and each PV- harness is connected to another EMI filtering unit 2.

[0054] The EMI filtering circuit includes multiple connection terminals 6, and each PV+ harness or each PV- harness connected to the same EMI filtering unit 2 is connected to a connection terminal 6, and the connection terminal 6 is electrically connected to the cable connector 3 in the EMI filtering unit 2.

[0055] In this embodiment, if Figure 3 As shown, three EMI filter units 2 are arranged on the bottom plate 1, wherein the first EMI filter unit 21 includes four safety capacitor groups 4, and the second EMI filter unit 22 is respectively provided with two safety capacitor groups 4. For example, for a photovoltaic system with four solar cell strings, each PV+ harness in the four PV output harnesses is respectively connected to the four safety capacitor groups 4 in the first EMI filter unit 21, and the other PV- harnesses are connected to the safety capacitor groups 4 of the second EMI filter unit 22 and the third filter unit.

[0056] In one embodiment, the photovoltaic system includes a plurality of solar cell strings and a plurality of solar controllers, each solar cell string has a PV output harness, each solar cell string is connected to a solar controller through the PV output harness, each solar controller is connected to a plurality of solar cell strings, and in the PV output harnesses of the plurality of solar cell strings connected to the same solar controller, each PV+ harness is connected to an EMI filter unit 2, and each PV- harness is connected to another EMI filter unit 2.

[0057] The PV output wire harnesses of multiple solar cell strings connected to the same solar controller are combined and divided into at least two lead-out wires after the combination. The at least two lead-out wires are respectively connected to two EMI filter units 2 according to the positive and negative electrical polarities.

[0058] In one embodiment, Figure 5 As shown, the PV output harnesses of multiple solar cell strings connected to the same solar controller are combined through a trip switch, and the EMI filter module is arranged at the rear end of the trip switch. That is, after being combined into an MPPT combined harness through the trip switch, EMI filtering is performed and then other functional components of the inverter are connected.

[0059] Embodiment 3:

[0060] This embodiment describes a photovoltaic inverter, which includes the EMI filter circuit described in Embodiment 2.

[0061] In summary, the present application optimizes the structure of the EMI filter module, facilitates the threading and fixing of the wiring harness when arranging the EMI filter circuit, and achieves the purpose of simplifying the connection and installation method of the output wiring harness of the solar cell string with the EMI filter board, thereby reducing production costs and assembly costs, and also enabling the cost of the photovoltaic inverter with the EMI filter circuit to be reduced accordingly.

[0062] The above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable people familiar with this technology to understand the content of the utility model and implement it accordingly. They cannot be used to limit the protection scope of the utility model. All equivalent changes or modifications made according to the spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. An EMI filter module, characterized in that: It comprises a base plate (1) and at least two EMI filter units (2) arranged on the base plate (1), wherein: Each EMI filter unit (2) comprises a cable connector (3) and at least two safety capacitor groups (4), the at least two safety capacitor groups (4) being electrically connected to the cable connector (3), and a through hole (5) for passing a PV wiring harness is provided on the bottom plate (1) corresponding to each safety capacitor group (4).

2. The EMI filter module according to claim 1, characterized in that: The safety capacitor group (4) comprises a first safety capacitor Cx, one end of the first safety capacitor Cx is connected to the cable connector (3), and the other end of the first safety capacitor Cx is connected to the cable connector (3) in another EMI filter unit (2).

3. The EMI filter module according to claim 1 or 2, characterized in that: The safety capacitor group (4) comprises a second safety capacitor Cy, one end of the second safety capacitor Cy is connected to the cable connector (3), and the other end is grounded.

4. An EMI filter circuit, used for performing EMI filtering on a plurality of PV output harnesses of a photovoltaic system, each PV output harness including a PV+ harness and a PV- harness, characterized in that: The EMI filtering circuit comprises an EMI filtering module as claimed in any one of claims 1 to 3, each PV+ harness in the plurality of PV output harnesses is connected to an EMI filtering unit (2), and each PV- harness is connected to another EMI filtering unit (2).

5. The EMI filter circuit according to claim 4, characterized in that: The EMI filter circuit comprises a plurality of connection terminals (6), each PV+ wiring harness or each PV- wiring harness connected to the same EMI filter unit (2) is connected to a connection terminal (6), and the connection terminal (6) is electrically connected to a cable connector (3) in the EMI filter unit (2).

6. The EMI filter circuit according to claim 4, characterized in that: The photovoltaic system comprises a plurality of solar cell strings and a plurality of solar energy controllers, each solar cell string having a PV output harness, each solar cell string being connected to a solar energy controller via the PV output harness, each solar energy controller being connected to a plurality of solar cell strings, each PV+ harness of the PV output harnesses of the plurality of solar cell strings being connected to an EMI filter unit (2), and each PV- harness being connected to another EMI filter unit (2).

7. The EMI filter circuit according to claim 6, characterized in that: PV output wire harnesses of a plurality of solar cell strings connected to the same solar controller are combined and divided into at least two lead-out wires after the combination. The at least two lead-out wires are respectively connected to two EMI filter units (2) according to positive and negative electrical polarities.

8. The EMI filter circuit according to claim 7, characterized in that: The PV output harnesses of a plurality of solar cell strings connected to the same solar controller are combined through a trip switch, and the EMI filter module is arranged at the rear end of the trip switch.

9. A photovoltaic inverter, characterized in that: The method comprises the EMI filter circuit as claimed in any one of claims 4 to 8.

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