EMC filter circuit

Abstract

The utility model relates to the technical field of filtering, and provides an EMC filter circuit, which comprises an X1 capacitor, an X2 capacitor and an X3 capacitor which are connected in parallel, magnetic rings FE1 and FE2, and a high-frequency inductor L1 which is connected in series. The Y capacitor Y1, the Y capacitor Y2, the Y capacitor Y3 and the Y capacitor Y4 are used for filtering common-mode signals. The circuit is designed to be a two-stage common mode inductance filter, the first stage is formed by connecting a capacitor X1, a magnetic ring FE1 and a capacitor X2 in parallel, and the second stage is formed by connecting the capacitor X2, a magnetic ring FE2 and a capacitor X3 in parallel. Y1 and Y2 are connected in parallel to an input side PE line, and Y3 and Y4 are connected to the midpoint of FE1 and FE2 and are connected to the PE line through L1 to form a low-pass filter. The capacitor is an X2 type safety capacitor, FE1 is an ultracrystalline magnetic ring, and FE2 is a ferrite magnetic ring. The EMC filter circuit is reasonable in structural design and scientific in element layout, reduces cost, improves market competitiveness, is easy to realize and expand, and is suitable for different application scenes.

Description

TECHNICAL FIELD

[0001] The utility model relates to filter technology field, concretely relates to a EMC filter circuit. BACKGROUND

[0002] EMC circuit, namely electromagnetic compatibility (Electromagnetic Compatibility) circuit, for electronic product, EMC circuit is used to ensure that equipment can work normally in electromagnetic environment, improves the resistance ability of electronic product to external electromagnetic interference, ensures that equipment can work normally when being interfered by other electromagnetic sources.

[0003] In prior art, the problems of most EMC circuits include: the common mode filter using single parameter leads to limited filter frequency range, and cannot comprehensively cope with high-frequency and low-frequency interference signals in complex electromagnetic environment; the circuit structure design lacks innovation and flexibility, cannot optimize filter effect according to different application scenarios, and unreasonable component layout and connection reduce filter effect and circuit stability; the common mode filter usually uses single material magnetic ring, and filter effect and frequency response are limited, especially in high-frequency or low-frequency band, filter performance declines, and there is lack of targeted material selection scheme; the overall filter effect is poor, cannot effectively filter various interference signals generated in the working process of electronic product, and affects the performance and market competitiveness of product in complex electromagnetic environment; common mode signal filtering is insufficient, especially the filter effect of common mode signal between the two lines on the input side is poor, leading to signal distortion and noise increase, affecting normal work of electronic product; and there is deficiency in preventing ground wire interference, especially when grounding is poor, interference signals are easy to be introduced into the circuit through the ground wire, leading to circuit performance decline and stability deterioration, and there is lack of targeted low-pass filter design scheme in prior art. CONTENT OF UTILITY MODEL

[0004] In order to solve the problems in the background art, the utility model provides an EMC filter circuit, which is provided with an input side and an output side, and comprises:

[0005] Capacitors X1, X2 and X3 connected in parallel in the circuit;

[0006] Magnetic rings FE1 and FE2;

[0007] Inductors L1 and L2 connected in series in the circuit, L1 is a high-frequency inductor;

[0008] Y capacitors Y1, Y2, Y3 and Y4, wherein Y1 and Y2 are connected in series on the input side and are connected in parallel on the PE line; Y3 and Y4 are connected in series at the midpoint of FE1 and FE2;

[0009] Y capacitor is a kind of safety capacitor, commonly used in the power line or high frequency circuit of electronic equipment, used to suppress common mode interference. It has two pins, generally connected across the power line of the fire line (L) and zero line (N), or the fire line (L) and the ground wire (PE). The main function of Y capacitor is to prevent high frequency interference signals on the power line from passing through the electronic equipment to the outside, while also preventing external high frequency interference signals from entering the internal of the electronic equipment.

[0010] Capacitor X1, magnetic ring FE1 and capacitor X2 are connected in parallel to form a first stage common mode inductance filter;

[0011] Capacitor X2 is used as a common part of the first stage and the second stage common mode inductance filter;

[0012] Capacitor X2, magnetic ring FE2 and capacitor X3 are connected in parallel to form a second stage common mode inductance filter;

[0013] Y1 and Y2 capacitors are connected in series and then connected in parallel to the PE line on the input side to filter out the common mode signals of the two lines on the input side;

[0014] Y3 and Y4 capacitors are connected in series and then connected to the midpoint of FE1 and FE2, and then connected to the PE line through L1 high frequency inductance to form a low pass filter.

[0015] Capacitors X1, X2 and X3 are X2 type safety capacitors, and X2 represents that the safety level (overvoltage level) of the capacitor is two levels, and the peak pulse voltage allowed in the application is not greater than 2.5kV.

[0016] FE1 is a super microcrystalline magnetic ring, and FE2 is a ferrite magnetic ring.

[0017] The beneficial effects achieved by the utility model are:

[0018] The EMC filter circuit of the utility model adopts magnetic rings of different materials to form two-stage common mode inductance filters, widens the filtering frequency range, and improves the anti-interference ability of electronic products. At the same time, through the design of two-stage common mode inductance filters and the series connection of Y capacitors, the filtering effect is significantly enhanced, signal distortion and noise are reduced, and the performance and stability of electronic products are improved. In addition, the circuit also forms a low pass filter to effectively prevent ground line interference and improve the stability and reliability of the circuit. The structure design is reasonable, the component layout is scientific, the cost is reduced, and the market competitiveness is improved. The electromagnetic compatibility problem is fully considered, and the electromagnetic compatibility of electronic products is significantly enhanced. The design is simple and clear, easy to implement and expand, and can flexibly adapt to different application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a circuit structure schematic diagram of the utility model. DETAILED DESCRIPTION

[0020] The technical solutions in the utility model will be described clearly and completely below in combination with the drawings in the utility model, and additionally, the forms of each structure described in the following embodiments are only examples, and the utility model is not limited to each structure described in the following embodiments, and all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the utility model.

[0021] Referring to Figure 1 An EMC filter circuit comprises capacitors X1, X2 and X3, all of which are X2 type safety capacitors and are connected in parallel in the circuit.

[0022] The magnetic ring FE1 is a super-microcrystalline magnetic ring, and the magnetic ring FE2 is a ferrite magnetic ring. The inductor L1 is a high-frequency inductor and is connected in series in the circuit.

[0023] The Y capacitors comprise Y capacitors Y1 and Y2, which are connected in series at the input side and are connected in parallel on the PE line. The Y capacitors Y3 and Y4 are connected in series at the midpoint of the magnetic rings FE1 and FE2.

[0024] The capacitor X1, the magnetic ring FE1 and the capacitor X2 are connected in parallel to form a first-stage common-mode inductive filter.

[0025] The capacitor X2 (as a common part), the magnetic ring FE2 and the capacitor X3 are connected in parallel to form a second-stage common-mode inductive filter.

[0026] The Y capacitors Y1 and Y2 are connected in series and are connected in parallel on the PE line at the input side.

[0027] The Y capacitors Y3 and Y4 are connected in series, are connected to the midpoint of the magnetic rings FE1 and FE2, and are connected to the PE line through the high-frequency inductor L1.

[0028] The working process of the EMC filter circuit is as follows:

[0029] Common-mode signal filtering When there is a common-mode signal at the input side, the Y capacitors Y1 and Y2 are connected in parallel on the PE line, and the common-mode signal of the two lines at the input side is filtered through the high-frequency characteristics thereof, so that signal distortion and noise are reduced.

[0030] First-stage common-mode inductive filtering The input signal first passes through the first-stage common-mode inductive filter composed of the capacitor X1, the magnetic ring FE1 and the capacitor X2. The super-microcrystalline magnetic ring FE1 provides good filtering effect in the first-stage filtering due to its high inductance, high magnetic flux density and low eddy current loss, especially in the low-frequency band.

[0031] Second stage common mode inductance filter, the signal after the first stage filter continues to pass through the second stage common mode inductance filter composed of capacitor X2 (common part), magnetic ring FE2 and capacitor X3. Ferrite magnetic ring FE2 further enhances the filtering effect at higher frequency band, improves the overall filtering performance.

[0032] Low pass filter prevents ground interference, Y capacitors Y3 and Y4 are connected in series to the midpoint of magnetic rings FE1 and FE2, and then connected to the PE line through high-frequency inductor L1, forming a low pass filter. This design effectively prevents interference signals introduced due to poor grounding, improves the circuit's resistance to ground interference, and ensures that electronic products can work normally even in the case of poor grounding.

[0033] Through the above working process, the EMC filter circuit can comprehensively cope with high-frequency and low-frequency interference signals in complex electromagnetic environments, improve the anti-interference ability, stability and reliability of electronic products.

[0034] The above only describes preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An EMC filter circuit, which is provided with an input side and an output side, characterized in that, Comprise: Capacitor X1, capacitor X2 and capacitor X3 in parallel in the circuit; Magnetic ring FE1 and magnetic ring FE2; Inductor L1 in series in the circuit, L1 is high frequency inductor; Y capacitor Y1, Y capacitor Y2, Y capacitor Y3 and Y capacitor Y4, wherein, Y1 and Y2 are in series at the input side and are in parallel on the PE line; Y3 and Y4 are in series at the midpoint of FE1 and FE2; Capacitor X1, magnetic ring FE1 and capacitor X2 are in parallel, forming the first stage common mode inductor filter; Capacitor X2 is used as the common part of the first stage and the second stage common mode inductor filter; Capacitor X2, magnetic ring FE2 and capacitor X3 are in parallel, forming the second stage common mode inductor filter; Y1 and Y2 capacitors are in series and are in parallel on the PE line at the input side, filtering the common mode signal of the two lines at the input side; Y3 and Y4 capacitors are in series and are connected to the midpoint of FE1 and FE2, and then through L1 high frequency inductor to the PE line, forming a low pass filter.

2. The EMC filter circuit of claim 1, wherein, Capacitor X1, capacitor X2 and capacitor X3 are X2 type safety capacitors.

3. The EMC filter circuit of claim 1, wherein, FE1 is a super microcrystalline magnetic ring, and FE2 is a ferrite magnetic ring.

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