Leakage current suppression circuit and power device

Abstract

The application discloses a leakage current suppression circuit and a power device. The leakage current suppression circuit comprises an inductance module, a first capacitance module and a second capacitance module. The inductance module can increase the input cable impedance, thereby reducing the leakage current passing through the leakage current suppression circuit. The first capacitance module and the second capacitance module are connected with the power input line. The equivalent capacitance values of the first capacitance module and the second capacitance module are not equal. The first capacitance module and the second capacitance module can bypass the leakage current with different frequencies to the ground, thereby further reducing the leakage current passing through the power input line.

Description

Technical Field

[0001] This application belongs to the field of power electronics technology, and in particular relates to a leakage current suppression circuit and power equipment. Background Technology

[0002] This invention relates to the field of power electronics technology, and particularly to a leakage current suppression circuit for frequency converters. During operation, the high-frequency switching of power devices in a frequency converter generates a high dv / dt common-mode voltage, resulting in leakage current through the parasitic capacitance between the motor and ground. This leakage current not only causes malfunctions of leakage current protection devices, affecting system reliability, but also generates electromagnetic interference, reducing equipment performance. Existing leakage current suppression technologies typically rely on external reactors or magnetic rings, which increase the impedance on the frequency converter's input lines. Such methods usually require external reactors, making them incompatible with the environmental requirements of miniaturized integrated cabinets. Furthermore, they can reduce the power frequency leakage current on the frequency converter's input side, even below the trigger threshold of the leakage current protection device, yet still trigger the device to trip. Therefore, there is an urgent need for a solution that effectively suppresses high-frequency leakage current while also being simple in structure and low in cost. Utility Model Content

[0003] The purpose of this application is to provide a leakage current suppression circuit and power equipment, which aims to solve the problems existing in traditional leakage current suppression technology.

[0004] A first aspect of this application provides a leakage current suppression circuit, comprising: an inductor module, one end of which is connected to a power input line; a first capacitor module, a first end of which is connected to the power input line, and a second end of which is grounded; and a second capacitor module, a first end of which is connected to the power input line, and a second end of which is grounded; wherein the equivalent capacitance value of the first capacitor module is less than the equivalent capacitance value of the second capacitor module.

[0005] In one embodiment, the first end of the inductor module is used to connect to the power grid, and the second end of the inductor module is used to connect to the leakage current protection device through the power input line.

[0006] In one embodiment, the power input line includes a first trace, a second trace, and a third trace; the first capacitor module includes a first capacitor, a second capacitor, and a third capacitor; the first end of the first capacitor is connected to the first trace, the first end of the second capacitor is connected to the second trace, the first end of the third capacitor is connected to the third trace, and the second ends of the first capacitor, the second capacitor, and the third capacitor are all connected to ground.

[0007] In one embodiment, the power input line includes multiple traces, the second capacitor module includes multiple capacitors, at least one capacitor is connected in series between the neutral point of the second capacitor module and any of the traces, and at least one capacitor is connected in series between the neutral point of the second capacitor module and the ground terminal.

[0008] In one embodiment, the second capacitor module includes a fourth capacitor, a fifth capacitor, a sixth capacitor, and a seventh capacitor; the first end of the fourth capacitor is connected to the first trace, and the connection point between the first end of the fourth capacitor and the first trace is between the first end of the first capacitor and the second end of the first trace; the second end of the fourth capacitor is connected to the neutral point of the second capacitor module; the first end of the fifth capacitor is connected to the second trace, and the connection point between the first end of the fifth capacitor and the second trace is between the first end of the second capacitor and the second end of the second trace; the second end of the fifth capacitor is connected to the neutral point of the second capacitor module; the first end of the sixth capacitor is connected to the third trace, and the connection point between the first end of the sixth capacitor and the third trace is between the first end of the third capacitor and the second end of the third trace; the second end of the sixth capacitor is connected to the neutral point of the second capacitor module; the first end of the seventh capacitor is connected to the neutral point of the second capacitor module; and the second end of the seventh capacitor is connected to ground.

[0009] In one embodiment, the inductor module includes a common-mode inductor. The first input terminal of the common-mode inductor is connected to the first output terminal of the power grid, the first output terminal of the common-mode inductor is connected to the first end of the first trace, the second input terminal of the common-mode inductor is connected to the second output terminal of the power grid, the second output terminal of the common-mode inductor is connected to the first end of the second trace, the third input terminal of the common-mode inductor is connected to the third output terminal of the power grid, and the third output terminal of the common-mode inductor is connected to the first end of the third trace.

[0010] In one embodiment, the first capacitor, the second capacitor, and the third capacitor are all Y capacitors.

[0011] In one embodiment, the fourth capacitor, the fifth capacitor, and the sixth capacitor are all X capacitors, and the seventh capacitor is a Y capacitor.

[0012] In one embodiment, the leakage current protection device includes a frequency converter circuit.

[0013] A second aspect of this application provides a power device including the leakage current suppression circuit described above.

[0014] The beneficial effects of this application embodiment compared to the prior art are as follows: The inductor module can increase the impedance of the input cable, thereby reducing the leakage current through the leakage current suppression circuit. By configuring a first capacitor module and a second capacitor module connected to the power input line, making their equivalent capacitance values ​​unequal, the first and second capacitor modules can bypass leakage currents at different frequencies to ground, further reducing the leakage current through the power input line. Attached Figure Description

[0015] Figure 1 A schematic diagram of a leakage current suppression circuit provided in an embodiment of this application; Figure 2 This is another schematic diagram of a leakage current suppression circuit provided in an embodiment of this application; Figure 3 A circuit diagram of a leakage current suppression circuit provided in an embodiment of this application; Figure 4 A schematic diagram of a frequency converter provided in an embodiment of this application; Figure 5 This is a schematic diagram of the structure of a frequency converter provided in one embodiment of this application; Figure 6 A waveform diagram of leakage current in a frequency converter without leakage current suppression circuit provided in an embodiment of this application; Figure 7 A waveform diagram of leakage current in a frequency converter equipped with a leakage current suppression circuit, provided as an embodiment of this application; Figure 8 A schematic diagram of an electrical device provided in an embodiment of this application. Detailed Implementation

[0016] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0017] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0018] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0019] Figure 1 A schematic diagram of a leakage current suppression circuit according to an embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and the details are as follows: A leakage current suppression circuit 10 includes: an inductor module 100, a first capacitor module 200, and a second capacitor module 300.

[0020] One end of the inductor module 100 is used to connect to the power input line.

[0021] The first terminal of the first capacitor module 200 is connected to the second terminal of the inductor module 100, and the second terminal of the first capacitor module 200 is grounded.

[0022] The first terminal of the second capacitor module 300 is connected to the input terminal of the leakage current protection device 30, and the second terminal of the second capacitor module 300 is grounded.

[0023] The connection point between the second capacitor module 300 and the power input line is between the first capacitor module 200 and the leakage current protection device 30. The equivalent capacitance value of the first capacitor module 200 is less than the equivalent capacitance value of the second capacitor module 300.

[0024] It should be noted that the equivalent capacitance value of the first capacitor module 200 refers to the capacitance value of this hypothetical single capacitor after simplifying and equating the first capacitor module 200 to a single capacitor. The equivalent capacitance value of the second capacitor module 300 is similar, and will not be described again in this embodiment.

[0025] The inductor module 100 increases the impedance of the input cable, thereby reducing the leakage current through the leakage current suppression circuit 10. By configuring the first capacitor module 200 and the second capacitor module 300 connected to the power input line, and making their equivalent capacitance values ​​unequal, the first capacitor module 200 and the second capacitor module 300 can bypass leakage current to ground at different frequencies, further reducing the leakage current through the power input line.

[0026] In one embodiment, such as Figure 2 As shown, the leakage current suppression circuit 10 is used to connect between the power grid 20 and the leakage current protection device 30.

[0027] The first end of the inductor module 100 is connected to the power grid 20, and the second end of the inductor module 100 is connected to the leakage current protection device 30 through the power input line.

[0028] The first terminal of the first capacitor module 200 is connected to the second terminal of the inductor module 100, and the second terminal of the first capacitor module 200 is grounded.

[0029] The first terminal of the second capacitor module 300 is connected to the input terminal of the leakage current protection device 30, and the second terminal of the second capacitor module 300 is grounded.

[0030] The connection point between the second capacitor module 300 and the power input line is between the first capacitor module 200 and the leakage current protection device 30. The equivalent capacitance value of the first capacitor module 200 is less than the equivalent capacitance value of the second capacitor module 300.

[0031] By placing the inductor module 100 between the power grid 20 and the leakage current protection device 30, the impedance of the input cable of the leakage current protection device 30 can be increased, making its return path line a high-resistance state, thereby reducing the leakage current through the leakage current protection device 30. By configuring a first capacitor module 200 and a second capacitor module 300 with different equivalent capacitance values, leakage currents of different frequencies can be bypassed to the ground terminal, preventing leakage current from entering the leakage current protection device 30.

[0032] Meanwhile, since the second capacitor module 300 is closer to the leakage current protection device 30 than the first capacitor module 200, in addition to suppressing high-frequency leakage current, it also serves to smooth the DC bus voltage of the leakage current protection device 30.

[0033] By moving the second capacitor module 300, which has a relatively large equivalent capacitance value, away from the inductor module 100, the problem of resonance between the second capacitor module 300 and the first inductor module 100 at a specific frequency can also be avoided.

[0034] In one embodiment, such as Figure 3 As shown, the power grid 20 includes a three-phase power grid, and the power input line includes a first line, a second line, and a third line. The first capacitor module 200 includes a first capacitor C1, a second capacitor C2, and a third capacitor C3. The first end of the first capacitor C1 is connected to the first line, the first end of the second capacitor C2 is connected to the second line, the first end of the third capacitor C3 is connected to the third line, and the second ends of the first capacitor C1, the second end of the second capacitor C2, and the second end of the third capacitor C3 are all connected to the ground.

[0035] Understandably, when powered by a three-phase power grid, the power input line needs to have three corresponding traces. The second ends of the first, second, and third traces can be connected to the leakage current protection device 30. The first, second, and third traces are directly grounded through the first capacitor C1, the second capacitor C2, and the third capacitor C3, respectively, which can quickly conduct the high-frequency leakage current on the first, second, and third traces to the ground, preventing the high-frequency leakage current from being transmitted to the leakage current protection device 30.

[0036] Furthermore, the first end of the first capacitor C1 is connected to the first end of the first trace, the first end of the second capacitor C2 is connected to the first end of the second trace, and the first end of the third capacitor C3 is connected to the first end of the third trace.

[0037] In one embodiment, the power input line includes multiple traces, the second capacitor module 300 includes multiple capacitors, at least one capacitor is connected in series between the neutral point of the second capacitor module 300 and any trace, and at least one capacitor is connected in series between the neutral point of the second capacitor module 300 and the ground terminal.

[0038] Understandably, the capacitor located between the neutral point and ground of the second capacitor module 300 and the capacitors located between the neutral point and each trace of the power input line of the second capacitor module 300 are connected in series. This can reduce the equivalent series inductance (ESL) of the second capacitor module 300, improve the characteristics of the second capacitor module 300 in the high-frequency range, make the bypass effect of the second capacitor module 300 on high-frequency leakage current better, and improve the ability to suppress high-frequency leakage current.

[0039] In one embodiment, such as Figure 3 As shown, the second capacitor module 300 includes a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, and a seventh capacitor C7. The first end of the fourth capacitor C4 is connected to the first trace, and the connection point between the first end of the fourth capacitor C4 and the first trace is between the first end of the first capacitor C1 and the second end of the first trace. The second end of the fourth capacitor C4 is connected to the neutral point of the second capacitor module 300. The first end of the fifth capacitor C5 is connected to the second trace, and the connection point between the first end of the fifth capacitor C5 and the second trace is between the first end of the second capacitor C2 and the second end of the second trace. The second end of the fifth capacitor C5 is connected to the neutral point of the second capacitor module 300. The first end of the sixth capacitor C6 is connected to the third trace, and the connection point between the first end of the sixth capacitor C6 and the third trace is between the first end of the third capacitor C3 and the second end of the third trace. The second end of the sixth capacitor C6 is connected to the neutral point of the second capacitor module 300. The first end of the seventh capacitor C7 is connected to the neutral point of the second capacitor module 300, and the second end of the seventh capacitor C7 is connected to ground.

[0040] The fourth capacitor C4 and the seventh capacitor C7 can be considered to be connected in series between the first trace and the ground terminal. The fifth capacitor C5 and the seventh capacitor C7 can be considered to be connected in series between the second trace and the ground terminal. The sixth capacitor C6 and the seventh capacitor C7 can be considered to be connected in series between the third trace and the ground terminal.

[0041] By connecting capacitors in series, the equivalent series inductance (ESL) of the second capacitor module 300 can be reduced, improving the characteristics of the second capacitor module 300 in the high-frequency range, making the bypass effect of the second capacitor module 300 on high-frequency leakage current better, and enhancing the ability to suppress high-frequency leakage current.

[0042] In some embodiments, such as Figure 3 As shown, the second capacitor module 300 also includes an eighth capacitor C8, which is connected in parallel with the seventh capacitor C7. The parallel connection of the eighth capacitor C8 and the seventh capacitor C7 allows for further adjustment of the capacitance value between the neutral point and ground of the second capacitor module 300.

[0043] In one embodiment, such as Figure 3 As shown, the inductor module 100 includes a common-mode inductor LF. The first input terminal of the common-mode inductor LF is connected to the first output terminal of the power grid 20. The first output terminal of the common-mode inductor LF is connected to the first end of the first trace. The second input terminal of the common-mode inductor LF is connected to the second output terminal of the power grid 20. The second output terminal of the common-mode inductor LF is connected to the first end of the second trace. The third input terminal of the common-mode inductor LF is connected to the third output terminal of the power grid 20. The third output terminal of the common-mode inductor LF is connected to the first end of the third trace.

[0044] When leakage current flows, the common-mode inductor LF will generate a large inductive reactance to the leakage current, thereby suppressing the leakage current and reducing the leakage current passing through the leakage current protection device 30.

[0045] In one embodiment, the first capacitor C1, the second capacitor C2, and the third capacitor C3 are all Y capacitors.

[0046] Specifically, the first capacitor C1, the second capacitor C2, and the third capacitor C3 are all nF-level Y capacitors.

[0047] Under high-frequency conditions, nF-level Y capacitors have relatively low capacitive reactance, effectively providing a low-impedance path to ground for high-frequency leakage currents. This allows these high-frequency components to be quickly bypassed to ground, thus preventing high-frequency leakage current from flowing into the leakage current protection device 30. It is understood that the specific capacitance values ​​of the first capacitor C1, the second capacitor C2, and the third capacitor C3 can be set according to actual needs.

[0048] In some embodiments, the first capacitor C1, the second capacitor C2, and the third capacitor C3 can all be ceramic capacitors.

[0049] For example, the values ​​of the first capacitor C1, the second capacitor C2, and the third capacitor C3 range from 1nF to 100nF.

[0050] In one embodiment, the fourth capacitor C4, the fifth capacitor C5, and the sixth capacitor C6 are all X capacitors, and the seventh capacitor C7 is a Y capacitor.

[0051] Specifically, the fourth capacitor C4, the fifth capacitor C5, and the sixth capacitor C6 are all uF-level X capacitors, and the seventh capacitor C7 is a uF-level Y capacitor. For example, the values ​​of the fourth capacitor C4, the fifth capacitor C5, the sixth capacitor C6, and the seventh capacitor C7 range from 0.1 uF to 10 uF.

[0052] Capacitors in the uF range can still provide good bypassing for low-frequency leakage currents (such as leakage currents with frequencies of several hundred hertz to tens of kilohertz). Understandably, the specific capacitance values ​​of the fourth capacitor C4, the fifth capacitor C5, the sixth capacitor C6, and the seventh capacitor C7 can be set according to actual needs.

[0053] In some embodiments, the fourth capacitor C4, the fifth capacitor C5, the sixth capacitor C6, and the seventh capacitor C7 can all be film capacitors. Connecting the capacitors in series can improve the overall voltage withstand capability of the second capacitor module 300, preventing the film capacitors of the second capacitor module 300 from being broken down under high voltage conditions, and ensuring the safe and stable operation of the circuit.

[0054] In one embodiment, the leakage current protection device 30 includes a frequency converter circuit.

[0055] By using the inductor module 100, the first capacitor module 200, and the second capacitor module 300, the high-frequency leakage current of the frequency converter circuit can be suppressed more accurately based on the frequency domain characteristics of the leakage current of the frequency converter circuit, and the cost is relatively small.

[0056] It is understood that the leakage current suppression circuit 10 can be a separate product, independently installed outside the leakage current protection device 30, or it can be integrated with the leakage current protection device 30. This application embodiment does not limit it.

[0057] Figure 4 A schematic diagram of a frequency converter according to an embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and the details are as follows: A frequency converter 40 includes a leakage current suppression circuit 10 as described in any of the above embodiments.

[0058] Specifically, such as Figure 4 , Figure 5As shown, the inverter 40 also includes an input terminal block 41, a rectifier circuit 42, and an inverter circuit 43. The input terminal block 41 is used to connect to the power grid 20. The input terminal of the leakage current suppression circuit 10 is connected to the input terminal block 41. The output terminal of the leakage current suppression circuit 10 is connected to the input terminal of the rectifier circuit 42. The output terminal of the rectifier circuit 42 is connected to the input terminal of the inverter circuit 43.

[0059] For example, the leakage current waveform in a frequency converter 40 without leakage current suppression circuit 10 is as follows: Figure 6 As shown, the leakage current waveform in the inverter 40 equipped with the leakage current suppression circuit 10 is as follows: Figure 7 As shown. Without any measures, the leakage current is mainly distributed in the frequency band below 200KHz, with the most significant leakage current in the 0-80KHz frequency band. The leakage current suppression circuit 10 can significantly reduce the high-frequency leakage current of the inverter 40, especially reducing the high-frequency leakage current in the frequency band near 40KHz by 0-10dB.

[0060] Figure 8 A schematic diagram of a power device according to an embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and the details are as follows: An electrical device 50 includes a leakage current suppression circuit 10 as described in any of the above embodiments.

[0061] Since the power equipment 50 includes the leakage current suppression circuit 10 as described in any of the above embodiments, the power equipment 50 has the beneficial effects of the leakage current suppression circuit 10 as described in any of the above embodiments, which will not be repeated here.

[0062] Specifically, the power equipment 50 can be energy storage equipment, charging equipment, and power generation equipment, etc.

[0063] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0064] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0065] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A leakage current suppression circuit, characterized by, include: An inductor module, one end of which is used to connect to a power input line; A first capacitor module, wherein a first terminal of the first capacitor module is connected to the power input line, and a second terminal of the first capacitor module is grounded; The second capacitor module has a first terminal connected to the power input line and a second terminal grounded. The equivalent capacitance value of the first capacitor module is less than the equivalent capacitance value of the second capacitor module.

2. The leakage current suppression circuit of claim 1, wherein, The first end of the inductor module is used to connect to the power grid, and the second end of the inductor module is used to connect to the leakage current protection device through the power input line.

3. The leakage current suppression circuit of claim 2, wherein, The power input line includes a first trace, a second trace, and a third trace. The first capacitor module includes a first capacitor, a second capacitor, and a third capacitor. The first end of the first capacitor is connected to the first trace, the first end of the second capacitor is connected to the second trace, the first end of the third capacitor is connected to the third trace, and the second ends of the first capacitor, the second capacitor, and the third capacitor are all connected to ground.

4. The leakage current suppression circuit as described in claim 3, characterized in that, The power input line includes multiple traces, the second capacitor module includes multiple capacitors, at least one capacitor is connected in series between the neutral point of the second capacitor module and any of the traces, and at least one capacitor is connected in series between the neutral point of the second capacitor module and the ground terminal.

5. The leakage current suppression circuit as described in claim 4, characterized in that, The second capacitor module includes a fourth capacitor, a fifth capacitor, a sixth capacitor, and a seventh capacitor. The first terminal of the fourth capacitor is connected to the first trace, and the connection point between the first terminal of the fourth capacitor and the first trace is between the first terminal of the first capacitor and the second terminal of the first trace. The second terminal of the fourth capacitor is connected to the neutral point of the second capacitor module. The first terminal of the fifth capacitor is connected to the second trace, and the connection point between the first terminal of the fifth capacitor and the second trace is between the first terminal of the second capacitor and the second terminal of the second trace. The second terminal of the fifth capacitor is connected to the neutral point of the second capacitor module. The first terminal of the sixth capacitor is connected to the third trace, and the connection point between the first terminal of the sixth capacitor and the third trace is between the first terminal of the third capacitor and the second terminal of the third trace. The second terminal of the sixth capacitor is connected to the neutral point of the second capacitor module. The first terminal of the seventh capacitor is connected to the neutral point of the second capacitor module, and the second terminal of the seventh capacitor is connected to ground.

6. The leakage current suppression circuit of claim 3, wherein, The inductor module includes a common-mode inductor. The first input terminal of the common-mode inductor is connected to the first output terminal of the power grid, the first output terminal of the common-mode inductor is connected to the first end of the first trace, the second input terminal of the common-mode inductor is connected to the second output terminal of the power grid, the second output terminal of the common-mode inductor is connected to the first end of the second trace, the third input terminal of the common-mode inductor is connected to the third output terminal of the power grid, and the third output terminal of the common-mode inductor is connected to the first end of the third trace.

7. The leakage current suppression circuit of claim 3, wherein The first capacitor, the second capacitor, and the third capacitor are all Y capacitors.

8. The leakage current suppression circuit of claim 5, wherein, The fourth, fifth, and sixth capacitors are all X capacitors, and the seventh capacitor is a Y capacitor.

9. The leakage current suppression circuit of any one of claims 2 to 8, wherein, The leakage current protection device includes a frequency converter circuit.

10. An electric power device, characterized by Includes the leakage current suppression circuit as described in any one of claims 1 to 9.

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