EMI filter with harmonic suppression function

Abstract

The utility model belongs to the technical field of electromagnetic compatibility, and particularly relates to an EMI filter with a harmonic suppression function, which comprises an EMI filter circuit, a harmonic suppression circuit and a connection relation thereof. According to the utility model, the harmonic suppression circuit is additionally arranged, so that harmonic current generated by nonlinear equipment can be filtered out, the interference of the harmonic current on the equipment is reduced, the electromagnetic compatibility test is not influenced, and meanwhile, the EMI filter circuit can filter out high and low frequency interference on the equipment; in addition, the harmonic suppression circuit and the EMI filter circuit are packaged in the same shell, so that the overall size of the filter is reduced, and the filter is light and handy.

Description

Technical Field

[0001] The utility model relates to the technical field of electromagnetic compatibility, and particularly relates to an EMI filter with a harmonic suppression function. Background Technique

[0002] With the development of science and technology and the improvement of industrial level and people's living standards, a large number of nonlinear electrical equipment have been put into operation in the power grid, resulting in an increasing proportion of harmonic components in the power grid. The harm caused by harmonics to the power system is very serious. Harmonics reduce the efficiency of power production, transmission and utilization, cause electrical equipment to overheat, generate vibration and noise, age the insulation, shorten the service life, and even cause failures and burnouts. Moreover, the electromagnetic compatibility requirements of instrument and equipment systems are becoming more and more strict. Externally to the power system, harmonics will cause serious interference to communication equipment and electronic equipment, resulting in the equipment being unable to work properly or even being damaged. Therefore, harmonic suppressors are used to solve this problem. However, traditional harmonic suppressors are large in size and heavy in weight, and only have a harmonic suppression function. Other electromagnetic compatibility tests cannot pass the experiment, resulting in many small devices being unable to be loaded. Even if the loading is successful, other electromagnetic compatibility experiments cannot pass the test, so electromagnetic compatibility needs to be considered again. Content of the Utility Model

[0003] The purpose of the utility model is to solve the technical problems existing in the background technique. For this reason, an EMI filter with a harmonic suppression function is provided.

[0004] In order to achieve the above purpose, the technical solutions adopted by the utility model are as follows:

[0005] An EMI filter with a harmonic suppression function includes an EMI filter circuit and a harmonic suppression circuit;

[0006] The EMI filter circuit includes inductors L1, L2, a resistor R, a common mode inductor L4, capacitors Cx2, Cy3, and Cy4;

[0007] Among them, the positive input end of inductor L1 is electrically connected to the positive input end of common mode inductor L4. One end of capacitor Cy3 is connected to the positive output end of common mode inductor L4, and the other end of capacitor Cy3 is grounded; the negative input end of inductor L2 is electrically connected to the negative input end of common mode inductor L4. One end of capacitor Cy4 is connected to the negative output end of common mode inductor L4, and the other end of capacitor Cy4 is grounded; a resistor R and a capacitor Cx2 are connected between the positive input end and the negative input end of common mode inductor L4, and the resistor R and the capacitor Cx2 are connected in parallel;

[0008] The harmonic suppression circuit includes an inductor L3 and a capacitor Cx1;

[0009] An inductor L3 and a capacitor Cx1 are connected between the positive input terminal and the negative input terminal of the common-mode inductor L4, and the inductor L3 and the capacitor Cx1 are connected in series.

[0010] The following is a further limited technical solution of the present invention. The positive pole of the input terminal of the EMI filter is electrically connected to one end of the inductor L1, the other end of the inductor L1 is electrically connected to the positive input terminal of the common-mode inductor L4, and the positive output terminal of the common-mode inductor L4 is electrically connected to the positive pole of the output terminal of the EMI filter; the negative pole of the input terminal of the EMI filter is electrically connected to one end of the inductor L2, the other end of the inductor L2 is electrically connected to the negative input terminal of the common-mode inductor L4, and the negative output terminal of the common-mode inductor L4 is electrically connected to the negative pole of the output terminal of the EMI filter.

[0011] The following is a further limited technical solution of the present invention. It further includes a metal housing, in which an EMI filter circuit and a harmonic suppression circuit are arranged, and three input terminal lead-out wires and two output terminal lead-out wires are arranged on both sides of the metal housing;

[0012] The two input terminal lead-out wires are respectively electrically connected to the inductor L1 and the inductor L2, and one input terminal lead-out wire is grounded;

[0013] The two output terminal lead-out wires are respectively electrically connected to the positive output terminal and the negative output terminal of the common-mode inductor L4.

[0014] Compared with the prior art, the present invention has the following technical effects:

[0015] By adding a harmonic suppression circuit, the present invention can filter out the harmonic current generated by non-linear devices, thereby reducing the interference of the harmonic current on the device and not affecting the electromagnetic compatibility test. At the same time, the EMI filter circuit can filter out high and low frequency interferences on the device; in addition, the harmonic suppression circuit and the EMI filter circuit are encapsulated in the same housing, making the overall volume of the filter smaller and lighter.

[0016] The present invention will be further described below in conjunction with the drawings and embodiments. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a circuit connection relationship diagram of the present invention;

[0019] Figure 2 It is a top - view structural schematic diagram of the present utility model;

[0020] Figure 3 is Figure 2 a cross - sectional structural schematic diagram of E - E in

[0021] Reference numerals: 1, metal housing; 2, input - end lead - out wire; 3, output - end lead - out wire. Specific embodiments

[0022] To make the above - mentioned objects, features and advantages of the present utility model more obvious and understandable, the following combines the accompanying drawings to make a detailed description of the specific embodiments of the present utility model. Many specific details are set forth in the following description in order to fully understand the present utility model. However, the present utility model can be implemented in many other ways different from those described herein. Those skilled in the art can make similar improvements without departing from the connotation of the present utility model. Therefore, the present utility model is not limited by the specific embodiments disclosed below.

[0023] As Figure 2 and 3 shown, a kind of EMI filter with harmonic suppression function is provided, which includes a metal housing. An EMI filtering circuit and a harmonic suppression circuit are arranged in the metal housing 1. Three input - end lead - out wires 2 (L, N, E) and two output - end lead - out wires 3 (L′, N′) are arranged on both sides of the metal housing. The input - end lead - out wire L serves as the positive pole of the input end of the EMI filter, the input - end lead - out wire N serves as the negative pole of the input end of the EMI filter, and the input - end lead - out wire E is grounded; the output - end lead - out wire L′ serves as the positive pole of the output end of the EMI filter, and the output - end lead - out wire N′ serves as the negative pole of the output end of the EMI filter. Potting the entire cavity inside the metal housing 1 can effectively reduce its vibration and heat generation.

[0024] 1. EMI filtering circuit

[0025] As Figure 1 shown, the EMI filtering circuit includes inductors L1, L2, resistor R, common - mode inductor L4, capacitors Cx2, Cy3, Cy4.

[0026] Among them, the positive pole of the input end of the EMI filter is electrically connected to one end of the inductor L1, the other end of the inductor L1 is electrically connected to the positive input end of the common - mode inductor L4, the positive output end of the common - mode inductor L4 is electrically connected to the positive pole of the output end of the EMI filter, one end of a capacitor Cy3 is connected to the positive output end of the common - mode inductor L4, and the other end of the capacitor Cy3 is grounded.

[0027] The negative terminal of the input end of the EMI filter is electrically connected to one end of the inductor L2. The other end of the inductor L2 is electrically connected to the negative input end of the common-mode inductor L4. The negative output end of the common-mode inductor L4 is electrically connected to the negative terminal of the output end of the EMI filter. One end of the capacitor Cy4 is connected to the negative output end of the common-mode inductor L4, and the other end of the capacitor Cy4 is grounded.

[0028] A resistor R and a capacitor Cx2 are connected between the positive input end and the negative input end of the common-mode inductor L4, and the resistor R and the capacitor Cx2 are connected in parallel.

[0029] 2. Harmonic suppression circuit (also known as LC series resonance frequency selection circuit)

[0030] As Figure 1 shown, the harmonic suppression circuit includes an inductor L3 and a capacitor Cx1. Among them, an inductor L3 and a capacitor Cx1 are connected between the positive input end and the negative input end of the common-mode inductor L4, and the inductor L3 and the capacitor Cx1 are connected in series.

[0031] In summary, as Figure 1 shown, a harmonic suppression circuit (also known as LC series resonance frequency selection circuit) is designed at the front end of the EMI filter circuit. When the circuit is powered on, the inductor L3 and the capacitor Cx1 are connected in series. When there is harmonic interference in the circuit, the inductor L3 and the capacitor Cx1 are at the resonance point, and the energy exchange between them reaches the maximum, forming a high-impedance state, and having frequency selectivity and filtering characteristics. The suppression of several harmonics can be selected by adjusting the values of the inductor L3 and the capacitor Cx1. The EMI filter circuit at the back end can also suppress high-frequency and low-frequency interference in other frequency bands.

[0032] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above, or modify it into an equivalent embodiment with equivalent changes. Therefore, all equivalent changes made according to the shape, structure and principle of the present invention without departing from the content of the technical solution of the present invention shall be covered by the protection scope of the present invention.

Claims

1. An EMI filter with harmonic suppression function, characterized in that, It includes an EMI filtering circuit and a harmonic suppression circuit; The EMI filtering circuit includes inductors L1, L2, resistor R, common-mode inductor L4, capacitors Cx2, Cy3, and Cy4; Among them, the positive input end of inductor L1 is electrically connected to the positive input end of common-mode inductor L4. One end of capacitor Cy3 is connected to the positive output end of common-mode inductor L4, and the other end of capacitor Cy3 is grounded. The negative input end of inductor L2 is electrically connected to the negative input end of common-mode inductor L4. One end of capacitor Cy4 is connected to the negative output end of common-mode inductor L4, and the other end of capacitor Cy4 is grounded. A resistor R and a capacitor Cx2 are connected between the positive and negative input ends of common-mode inductor L4, and resistor R and capacitor Cx2 are in parallel; The harmonic suppression circuit includes inductor L3 and capacitor Cx1; An inductor L3 and a capacitor Cx1 are connected between the positive and negative input ends of common-mode inductor L4, and inductor L3 and capacitor Cx1 are in series.

2. An EMI filter with harmonic suppression function as described in claim 1, characterized in that, The positive pole of the input end of the EMI filter is electrically connected to one end of inductor L1, the other end of inductor L1 is electrically connected to the positive input end of common-mode inductor L4, and the positive output end of common-mode inductor L4 is electrically connected to the positive pole of the output end of the EMI filter. The negative pole of the input end of the EMI filter is electrically connected to one end of inductor L2, the other end of inductor L2 is electrically connected to the negative input end of common-mode inductor L4, and the negative output end of common-mode inductor L4 is electrically connected to the negative pole of the output end of the EMI filter.

3. An EMI filter with a harmonic suppression function as described in claim 1, characterized in that, It also includes a metal housing. The EMI filtering circuit and the harmonic suppression circuit are arranged in the metal housing. Three input terminal lead-out wires and two output terminal lead-out wires are arranged on both sides of the metal housing; The two input terminal lead-out wires are respectively electrically connected to inductor L1 and inductor L2, and one input terminal lead-out wire is grounded; The two output terminal lead-out wires are respectively electrically connected to the positive output end and the negative output end of common-mode inductor L4.

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