Power supply electromagnetic compatibility filter

Abstract

The invention discloses a power supply electromagnetic compatibility filter which comprises a three-phase alternating current input end, a first-stage differential mode capacitor circuit, a first-stage differential mode inductor circuit, a common mode capacitor circuit, a second-stage differential mode capacitor circuit, a second-stage differential mode inductor circuit and a three-phase alternating current output end which are in communication connection in sequence. Wherein the first-stage differential mode capacitor circuit, the first-stage differential mode inductor circuit, the second-stage differential mode capacitor circuit and the second-stage differential mode inductor circuit form a differential mode signal suppression circuit, and the differential mode signal suppression circuit is used for suppressing differential mode interference signals in a three-phase alternating current circuit; the first-stage differential mode inductance circuit, the common mode capacitance circuit and the second-stage differential mode inductance circuit form a common mode signal suppression circuit, and the common mode signal suppression circuit is used for suppressing common mode interference signals in the three-phase alternating current circuit, so that the problems of substandard electromagnetic compatibility, relatively high cost and huge size in the existing filtering technology are solved.

Description

Technical Field

[0001] The present application relates to the technical field of filter design, and in particular to a power supply electromagnetic compatibility filter. Background Art

[0002] With the rapid development of science and technology, electrical equipment is widely used, and the electromagnetic interference generated by electronic devices is becoming more and more serious. It not only affects the normal operation of other electronic components, but also brings certain harm to the entire system. There are generally two ways of electromagnetic interference, one is radiation interference and the other is conduction interference. In engineering, shielding, grounding and filtering methods are usually used to effectively suppress electromagnetic interference. Shielding technology and grounding technology can have a certain filtering effect, but cannot directly and effectively solve the problem of excessive electromagnetic interference. Filtering technology is the most commonly used, most effective and most economical technical means, which is usually used to suppress electromagnetic conduction interference. Existing filtering technology has the problems of substandard electromagnetic compatibility, high cost and large size. Summary of the invention

[0003] The main purpose of the present application is to provide a power supply electromagnetic compatibility filter, aiming to solve the problems of existing filtering technology such as non-compliance with electromagnetic compatibility standards, high cost and large size.

[0004] To achieve the above-mentioned purpose, the present application provides a power supply electromagnetic compatibility filter, comprising: a three-phase AC input end, a first-stage differential mode capacitor circuit, a first-stage differential mode inductor circuit, a common mode capacitor circuit, a second-stage differential mode capacitor circuit, a second-stage differential mode inductor circuit and a three-phase AC output end which are sequentially connected in communication; wherein the first-stage differential mode capacitor circuit, the first-stage differential mode inductor circuit, the second-stage differential mode capacitor circuit and the second-stage differential mode inductor circuit constitute a differential mode signal suppression circuit, and the differential mode signal suppression circuit is used to suppress the differential mode interference signal in the three-phase AC circuit; the first-stage differential mode inductor circuit, the common mode capacitor circuit and the second-stage differential mode inductor circuit constitute a common mode signal suppression circuit, and the common mode signal suppression circuit is used to suppress the common mode interference signal in the three-phase AC circuit.

[0005] Optionally, the three-phase AC input terminal includes an A-phase input terminal, a B-phase input terminal, and a C-phase input terminal, and the first-stage differential mode capacitor circuit includes: a first capacitor, a first end of which is connected to the A-phase input terminal, and a second end of which is connected to the B-phase input terminal; a second capacitor, a first end of which is connected to the B-phase input terminal, and a second end of which is connected to the C-phase input terminal; a third capacitor, a first end of which is connected to the A-phase input terminal, and a second end of which is connected to the C-phase input terminal.

[0006] Optionally, the three-phase AC input terminal includes an A-phase output terminal, a B-phase output terminal, and a C-phase output terminal, and the first-level differential-mode inductor circuit and the second-level differential-mode inductor circuit are connected in series; the first-level differential-mode inductor includes a first inductor, a second inductor and a third inductor, and the second-level differential-mode inductor includes a fourth inductor, a fifth inductor and a sixth inductor; the first end of the first inductor is connected to the A-phase input terminal, the second end is connected to the first end of the fourth inductor, and the second end of the fourth inductor is connected to the A-phase output terminal; the first end of the second inductor is connected to the B-phase input terminal, the second end is connected to the first end of the fifth inductor, and the second end of the fifth inductor is connected to the B-phase output terminal; the first end of the third inductor is connected to the C-phase input terminal, the second end is connected to the first end of the sixth inductor, and the second end of the sixth inductor is connected to the C-phase output terminal.

[0007] Optionally, the second-stage differential mode capacitor circuit includes: a fourth capacitor, a first end of which is connected to the second end of the first inductor, and a second end of which is connected to the second end of the second inductor; a fifth capacitor, a first end of which is connected to the second end of the second inductor, and a second end of which is connected to the second end of the third inductor; and a sixth capacitor, a first end of which is connected to the second end of the first inductor, and a second end of which is connected to the second end of the third inductor.

[0008] Optionally, the common-mode capacitor circuit includes: a seventh capacitor, a first end of which is connected to the second end of the first inductor, and a second end of which is grounded; an eighth capacitor, a first end of which is connected to the second end of the second inductor, and a second end of which is grounded; and a ninth capacitor, a first end of which is connected to the second end of the third inductor, and a second end of which is grounded.

[0009] Optionally, the capacitance of each of the first capacitor, the second capacitor, the third capacitor, the fourth capacitor, the fifth capacitor, the sixth capacitor, the seventh capacitor, the eighth capacitor and the ninth capacitor ranges from 0.1 μF to 0.9 μF.

[0010] Optionally, the inductance of each of the first inductor, the second inductor, the third inductor, the fourth inductor, the fifth inductor, and the sixth inductor ranges from 2.1 mH to 2.9 mH.

[0011] A power supply electromagnetic compatibility filter proposed in an embodiment of the present application comprises a three-phase AC input terminal, a first-stage differential mode capacitor circuit, a first-stage differential mode inductor circuit, a common mode capacitor circuit, a second-stage differential mode capacitor circuit, a second-stage differential mode inductor circuit and a three-phase AC output terminal which are sequentially communicatively connected; wherein the first-stage differential mode capacitor circuit, the first-stage differential mode inductor circuit, the second-stage differential mode capacitor circuit and the second-stage differential mode inductor circuit constitute a differential mode signal suppression circuit, and the differential mode signal suppression circuit is used to suppress differential mode interference signals in the three-phase AC circuit; the first-stage differential mode inductor circuit, the common mode capacitor circuit and the second-stage differential mode inductor circuit constitute a common mode signal suppression circuit, and the common mode signal suppression circuit is used to suppress common mode interference signals in the three-phase AC circuit, thereby solving the problems of electromagnetic compatibility failure, high cost and large size in the existing filtering technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of the impedance mismatch principle of the filter design in this application;

[0013] Figure 2 This is a schematic diagram of the filter insertion loss circuit model in this application;

[0014] Figure 3 A schematic diagram of a filter circuit provided in an embodiment of the present application;

[0015] Figure 4 A schematic diagram of the filter structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0016] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0017] The present invention adopts the following technical scheme: a three-phase power supply electromagnetic compatibility filter, including impedance mismatch principle, insertion loss calculation, filtering circuit, etc.

[0018] For passive filters, impedance mismatch will produce insertion loss. Selecting the type and parameters of components in the filter circuit is an important design principle for suppressing conducted electromagnetic interference. In actual engineering design, the input and output (source and load) impedances of passive filters are usually equivalent to 50Ω, and when the filter is actually tested for insertion loss, the source and load impedances are also 50Ω. Therefore, the filter design generally sets the source and load impedances to 50Ω. There is a general principle for filter design: within the frequency range of filtering, the topology of the filter circuit needs to be selected according to the source impedance and load impedance of the input and output ends of the filter common and differential mode circuits, according to the impedance mismatch principle. The common mode circuit needs to be designed according to the high and low impedance mismatch principles. When designing, inductors and smaller common mode capacitors need to be used. However, since the common mode capacitor is very small, the effect of impedance mismatch is extremely limited at low frequencies, and the insertion loss suppression of low frequency circuits mainly depends on the design of inductors. Since devices with differential-mode circuits have higher power, the reactive power consumption caused by differential-mode capacitance has less impact on the devices. That is, the capacitance of differential-mode circuits is less restricted and can be designed according to the impedance mismatch principle.

[0019] Insertion loss is used to describe the filter's ability to suppress interference noise. It is defined as the ratio of the power transmitted from the noise source to the load when no filter is connected to the power transmitted from the noise source to the load after the filter is connected, expressed in dB (decibel). The insertion loss is calculated as follows:

[0020] IL10log

[0021]

[0022] Through the analysis of the test results and the internal circuit, a filter circuit based on the combination of L and C components is used to achieve the filtering function. Usually the switching frequency energy attenuates greatly after 10 times the frequency, and the interference exceeds the standard frequency band of 100kHz to 500kHz, and exceeds the limit by 10dB, so a low-pass filter is selected.

[0023] like Figure 1 As shown, when the source impedance or load impedance is low (usually reflected as capacitance), an inductor is selected in series with it; when the source impedance or load impedance is high (usually reflected as inductance), a capacitor is required to be connected in parallel with it. According to the test exceeding the standard value, an inductor and a smaller common-mode capacitor are used to suppress the common-mode interference signal, and the differential-mode circuit is designed according to the impedance mismatch principle to suppress the differential-mode signal interference.

[0024] like Figure 2As shown, in order to calculate the value of insertion loss, draw the original circuit and the access filter circuit model, calculate the corresponding value according to the circuit characteristics and the definition of insertion loss calculation, notify the experimental test value, select the corresponding capacitance and inductance values, and calculate the insertion loss. If it is lower than the exceeding value, the electromagnetic compatibility index can be completed.

[0025] like Figure 3 As shown, due to the presence of integrated circuits inside the distribution box, mainly including AC / DC power supply, control circuit, digital signal processing and analog signal processing, the interference sources include the operating frequency and high-order harmonic interference of the internal AC / DC rectifier circuit and the switching tube of the power module, the operating frequency and high-order harmonic interference of the clock signal, the control signal, the rising / falling edge interference of the pulse signal and the interference of high-order harmonics, etc., which will cause the electromagnetic compatibility test to fail to meet the requirements.

[0026] According to the requirements and design ideas of the above-mentioned design, through the analysis of the test results and the internal circuit, it is obtained that the present application provides a power supply electromagnetic compatibility filter, and the power supply electromagnetic compatibility filter 10 may include: a three-phase AC input terminal 101, a first-level differential mode capacitor circuit 102, a first-level differential mode inductor circuit 103, a common-mode capacitor circuit 104, a second-level differential mode capacitor circuit 105, a second-level differential mode inductor circuit 106 and a three-phase AC output terminal 107 which are sequentially connected in communication; wherein the first-level differential mode capacitor circuit 102, the first-level differential mode inductor circuit 103, the second-level differential mode capacitor circuit 105 and the second-level differential mode inductor circuit 106 constitute a differential mode signal suppression circuit, and the differential mode signal suppression circuit is used to suppress the differential mode interference signal in the three-phase AC circuit; the first-level differential mode inductor circuit 103, the common-mode capacitor circuit 104 and the second-level differential mode inductor circuit 106 constitute a common-mode signal suppression circuit, and the common-mode signal suppression circuit is used to suppress the common-mode interference signal in the three-phase AC circuit.

[0027] In an embodiment of the present invention, the three-phase AC input terminal 101 includes an A-phase input terminal a, a B-phase input terminal b, and a C-phase input terminal c, and the first-stage differential mode capacitor circuit 102 includes a first capacitor C1, a second capacitor C2, and a third capacitor C3, wherein the first end of the first capacitor C1 is connected to the A-phase input terminal a, and the second end is connected to the B-phase input terminal; the first end of the second capacitor C2 is connected to the B-phase input terminal b, and the second end is connected to the C-phase input terminal; the first end of the third capacitor C3 is connected to the A-phase input terminal a, and the second end is connected to the C-phase input terminal.

[0028] In an embodiment of the present invention, the three-phase AC input terminal 101 includes an A-phase output terminal, a B-phase output terminal, and a C-phase output terminal, and the first differential-mode inductor circuit 103 and the second differential-mode inductor circuit 106 are connected in series; the first differential-mode inductor includes a first inductor L1, a second inductor L2, and a third inductor L3, and the second differential-mode inductor includes a fourth inductor L4, a fifth inductor L5, and a sixth inductor L6; a first end of the first inductor L1 is connected to the A-phase input terminal a, a second end is connected to the first end of the fourth inductor L4, and a second end of the fourth inductor L4 is connected to the A-phase output terminal d; a first end of the second inductor L2 is connected to the B-phase input terminal b, a second end is connected to the first end of the fifth inductor L5, and a second end of the fifth inductor L5 is connected to the B-phase output terminal e; a first end of the third inductor L3 is connected to the C-phase input terminal c, a second end is connected to the first end of the sixth inductor L6, and a second end of the sixth inductor L6 is connected to the C-phase output terminal f.

[0029] In an embodiment of the present invention, the second-stage differential mode capacitor circuit 105 includes a fourth capacitor C4, a fifth capacitor C5 and a sixth capacitor C6, wherein a first end of the fourth capacitor C4 is connected to the second end of the first inductor L1, and a second end is connected to the second end of the second inductor L2; a first end of the fifth capacitor C5 is connected to the second end of the second inductor L2, and a second end is connected to the second end of the third inductor L3; a first end of the sixth capacitor C6 is connected to the second end of the first inductor L1, and a second end is connected to the second end of the third inductor L3.

[0030] In an embodiment of the present invention, the common-mode capacitor circuit 104 includes a seventh capacitor C7, an eighth capacitor C8 and a ninth capacitor C9, wherein a first end of the seventh capacitor C7 is connected to the second end of the first inductor L1, and a second end is grounded E; a first end of the eighth capacitor C8 is connected to the second end of the second inductor L2, and a second end is grounded E; a first end of the ninth capacitor C9 is connected to the second end of the third inductor L3, and a second end is grounded E.

[0031] In the embodiment of the present invention, the capacitance values ​​of the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, the fifth capacitor C5 and the sixth capacitor C6 range from 0.1 μF to 0.9 μF.

[0032] Exemplarily, the capacitance of each capacitor from the first capacitor to the sixth capacitor may be 0.05 μF, 0.1 μF, 0.4 μF, 0.8 μF, 0.9 μF, or 1 μF.

[0033] In an embodiment of the present invention, the capacitance values ​​of the seventh capacitor, the eighth capacitor and the ninth capacitor are all in the range of 0.4 μF to 0.5 μF.

[0034] Exemplarily, the capacitance of each of the first capacitor to the sixth capacitor may be 0.4 μF, 0.43 μF, 0.47 μF, 0.5 μF and 0.51 μF.

[0035] In the embodiment of the present invention, the inductance of each of the first inductor L1 , the second inductor L2 , the third inductor L3 , the fourth inductor L4 , the fifth inductor L5 , and the sixth inductor L6 ranges from 2.1 mH to 2.9 mH.

[0036] Specifically, the values ​​of the inductors can be 2.0mH, 2.1mH, 2.3mH, 2.5mH, 2.9mH and 2.7mH.

[0037] In summary, the present invention adopts a filter circuit based on a combination of L and C components to realize the filtering function, and a low-pass filter is selected. This filter circuit adopts an enhanced filter, with a total of 5 levels of circuits, among which C1, C2, C3, C4, C5, and C6 are differential mode capacitors, all of which are 0.5μF in size, C7, C8, and C9 are common mode capacitors, with a size of 0.47μF, and L1, L2, L3, L4, L5, and L6 are common mode inductors, with a size of 2.5mH. The filter circuit composed of a combination of LC components is used to filter the distribution box, which can effectively filter out differential mode interference signals and common mode interference signals in the circuit and meet electromagnetic compatibility requirements.

[0038] like Figure 4 As shown, Figure 4 The three-phase power filter has a small size and a simple structure. It can be installed inside the distribution box without affecting the normal operation of other components. This filter has a good filtering effect and a stable working state, and can continue to develop in the field of electromagnetic compatibility.

[0039] This application first understands the impedance adaptation principle and the insertion loss calculation method, and then uses the filter circuit composed of LC components to design a filter for the problem of non-compliance of the distribution box electromagnetic compatibility, and selects the parameters of the capacitor and inductor according to the exceeded values, and designs a five-level filter circuit, which successfully solves the problem of excessive electromagnetic compatibility of the distribution box. After experimental testing, the three-phase power filter has stable performance and good filtering effect, and meets the national standard electromagnetic compatibility test requirements through experimental simulation and experimental testing.

[0040] Compared with the prior art, the effects achieved by this technical solution are:

[0041] 1. Good filtering performance, meeting the requirements of electromagnetic compatibility test. The three-phase power filter of the present invention has been verified by electromagnetic compatibility test, and a certain distribution box meets the requirements of national standard electromagnetic compatibility test;

[0042] 2. High economic efficiency and controllable cost. The technology of the present invention not only ensures electromagnetic compatibility, but also takes into account cost performance, and can be effectively promoted in the field of electromagnetic compatibility;

[0043] 3. The filter has a compact structure and small size. It can be installed inside the distribution box without occupying the original device position and affecting the normal operation of other devices.

[0044] 4. Integrated design, simplified structure, easy to install.

[0045] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A power supply electromagnetic compatibility filter, characterized in that: include A three-phase AC input terminal, a first-stage differential mode capacitor circuit, a first-stage differential mode inductor circuit, a common mode capacitor circuit, a second-stage differential mode capacitor circuit, a second-stage differential mode inductor circuit and a three-phase AC output terminal that are sequentially connected in communication; Wherein, the first-stage differential mode capacitor circuit, the first-stage differential mode inductor circuit, the second-stage differential mode capacitor circuit and the second-stage differential mode inductor circuit constitute a differential mode signal suppression circuit, and the differential mode signal suppression circuit is used to suppress differential mode interference signals in a three-phase AC circuit; The first-stage differential-mode inductance circuit, the common-mode capacitance circuit and the second-stage differential-mode inductance circuit constitute a common-mode signal suppression circuit, and the common-mode signal suppression circuit is used to suppress the common-mode interference signal in the three-phase AC circuit.

2. The power supply electromagnetic compatibility filter according to claim 1, characterized in that: The three-phase AC input terminal includes an A-phase input terminal, a B-phase input terminal, and a C-phase input terminal, and the first-stage differential mode capacitor circuit includes: A first capacitor, a first end of which is connected to the A-phase input end, and a second end of which is connected to the B-phase input end; A second capacitor, a first end of which is connected to the B-phase input terminal, and a second end of which is connected to the C-phase input terminal; A third capacitor has a first end connected to the A-phase input end and a second end connected to the C-phase input end.

3. The power supply electromagnetic compatibility filter according to claim 2, characterized in that: The three-phase AC output terminal includes an A-phase output terminal, a B-phase output terminal, and a C-phase output terminal, and the first-stage differential-mode inductor circuit and the second-stage differential-mode inductor circuit are connected in series; The first-level differential mode inductor includes a first inductor, a second inductor and a third inductor, and the second-level differential mode inductor includes a fourth inductor, a fifth inductor and a sixth inductor; The first end of the first inductor is connected to the A-phase input end, the second end of the first inductor is connected to the first end of the fourth inductor, and the second end of the fourth inductor is connected to the A-phase output end; A first end of the second inductor is connected to the B-phase input end, a second end of the second inductor is connected to the first end of the fifth inductor, and a second end of the fifth inductor is connected to the B-phase output end; A first end of the third inductor is connected to the C-phase input end, a second end of the third inductor is connected to the first end of the sixth inductor, and a second end of the sixth inductor is connected to the C-phase output end.

4. The power supply electromagnetic compatibility filter according to claim 3, characterized in that: The second-stage differential mode capacitor circuit comprises: a fourth capacitor, a first end of which is connected to the second end of the first inductor, and a second end of which is connected to the second end of the second inductor; a fifth capacitor, a first end of which is connected to the second end of the second inductor, and a second end of which is connected to the second end of the third inductor; A sixth capacitor has a first end connected to the second end of the first inductor, and a second end connected to the second end of the third inductor.

5. The power supply electromagnetic compatibility filter according to claim 4, characterized in that: The common mode capacitor circuit comprises: a seventh capacitor, a first end of which is connected to the second end of the first inductor, and a second end of which is grounded; an eighth capacitor, a first end of which is connected to the second end of the second inductor, and a second end of which is grounded; A ninth capacitor has a first end connected to the second end of the third inductor and a second end grounded.

6. The power supply electromagnetic compatibility filter according to claim 4, characterized in that: The capacitance value range of each of the first capacitor, the second capacitor, the third capacitor, the fourth capacitor, the fifth capacitor and the sixth capacitor is 0.1 μF to 0.9 μF.

7. The power supply electromagnetic compatibility filter according to claim 5, characterized in that: The capacitance values ​​of the seventh capacitor, the eighth capacitor and the ninth capacitor are all in the range of 0.4 μF to 0.5 μF.

8. The power supply electromagnetic compatibility filter according to claim 3, characterized in that: The inductance value range of each of the first inductor, the second inductor, the third inductor, the fourth inductor, the fifth inductor, and the sixth inductor is 2.1 mH to 2.9 mH.

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