Differential and common mode integrated inductor with adjustable inductance and EMI (Electro-Magnetic Interference) filter

Abstract

The utility model discloses an inductance-adjustable differential and common mode integrated inductor and an EMI filter, and belongs to the technical field of differential and common mode integrated inductors. An inductance-adjustable differential and common mode integrated inductor comprises a closed magnetic core and two groups of coil windings which are symmetrically wound on the closed magnetic core, and further comprises two groups of symmetrically distributed magnetic sheets which are arranged in the closed magnetic core in a sliding mode, and the two groups of coil windings are symmetrical about the middle surface of the two groups of magnetic sheets. An adjusting part used for driving the magnetic sheets to slide is arranged in the closed magnetic core, and during use, the two sets of magnetic sheets are far away from each other or close to each other along the axis of the closed magnetic core; the magnetic sheets can be ejected to the two sides by tightening the screws, so that the opposite area and the up-down gap of the upper magnetic sheet and the lower magnetic sheet are adjusted, the magnetic resistance of the magnetic sheets and the magnetic resistance of air are adjusted, the magnetic resistance of a middle magnetic circuit is adjusted, the effect of adjusting the sensing value is achieved, and the structure is simple.

Description

Technical Field

[0001] The utility model relates to the technical field of differential and common mode integrated inductors, in particular to a differential and common mode integrated inductor with adjustable inductance and an EMI filter. Background Art

[0002] EMI (electromagnetic interference) noise from electronic devices can enter the power grid and pollute it. At the same time, EMI noise from the power grid can also enter electronic devices, potentially causing operational instability. Therefore, EMI limits are part of equipment specifications. EMI can be divided into common-mode interference and differential-mode interference based on waveform characteristics. Common-mode interference is interference noise signals with similar amplitudes and phases on a pair of transmission lines; differential-mode interference is interference noise signals with similar amplitudes but opposite phases on a pair of transmission lines. It overlaps with the transmission signals on the transmission lines and is generally indistinguishable. Currently, common-mode inductors are made by winding two identical coils of enameled wire around a closed magnetic core. The resulting common-mode inductance filters or suppresses common-mode noise interference in circuits. Alternatively, a single-coil inductor (commonly known as a differential-mode inductor) is used to filter or suppress differential-mode noise interference in circuits. In most anti-EMI modules, using only common-mode filter inductors while omitting differential-mode filter inductors makes it difficult to achieve good filtering effects. Using both types of inductors increases the cost of the filter circuit. Therefore, integrated common-mode / differential-mode filter inductors have become a trend in the application of anti-EMI devices in electronic equipment.

[0003] Integrated common-mode and differential-mode inductors combine common-mode and differential-mode filtering, offering excellent filtering performance and effectively suppressing various noise interferences. Their low DC resistance and insertion loss prevent significant signal attenuation. Their compact size and minimal footprint facilitate compact designs, making them popular with power supply manufacturers. However, the differential-mode inductance of these integrated common-mode inductors is the leakage inductance between the left and right coils, making it difficult to accurately calculate and adjust. This results in long prototyping cycles and high core mold manufacturing costs. Utility Model Content

[0004] The purpose of the utility model is to solve the problem in the prior art that the differential mode inductance of the differential and common mode integrated inductor is the leakage inductance between the left and right coils, which is difficult to accurately calculate and adjust, resulting in a long proofing cycle and high core mold manufacturing costs. The utility model proposes an adjustable inductance differential and common mode integrated inductor and EMI filter.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A differential common-mode integrated inductor with adjustable inductance comprises a closed magnetic core and two groups of coil windings symmetrically wound on the closed magnetic core. It also comprises two groups of symmetrically distributed magnetic sheets, both of which are slidably arranged in the closed magnetic core. The two groups of coil windings are symmetrical about the middle plane of the two groups of magnetic sheets, and an adjustment part for driving the magnetic sheets to slide is provided in the closed magnetic core. When in use, the two groups of magnetic sheets move away from or approach each other along the axis of the closed magnetic core.

[0007] In order to facilitate the adjustment of the spacing between the magnetic sheets, preferably, the adjustment part includes a partition arranged in the closed magnetic core, and the two groups of magnetic sheets are slidably arranged in the partition. Two groups of screws are threaded on the partition, and one end of the two groups of screws respectively abuts against the opposite surfaces of the two groups of magnetic sheets.

[0008] In order to improve the adjustment effect of the magnetic resistance between the magnetic sheets, further, the two groups of magnetic sheets are both in a right-angled trapezoidal structure, and the surfaces where the hypotenuses are located are adjacent surfaces, and one end of the two groups of screws respectively abuts against the short bottom edges of the two groups of magnetic sheets.

[0009] In order to have an insulating effect, the partition is further made of bakelite.

[0010] Preferably, the magnetic sheet is made of soft magnetic material.

[0011] An EMI filter includes a filter body, wherein the filter body includes an inductor, a capacitor and a resistor connected in series or in parallel to form an anti-electromagnetic interference filter circuit network, and the inductor adopts the above-mentioned differential common mode integrated inductor with adjustable inductance.

[0012] Compared with the prior art, the present invention provides an integrated differential and common mode inductor and EMI filter with adjustable inductance, which has the following beneficial effects:

[0013] 1. This differential common-mode integrated inductor with adjustable inductance can push the magnetic sheet to both sides by tightening the screws, thereby adjusting the facing area and the upper and lower gaps between the upper and lower magnetic sheets, thereby adjusting the magnetic resistance of the magnetic sheet and the air resistance, thereby adjusting the magnetic resistance of the middle magnetic circuit to achieve the effect of adjusting the inductance, and has a simple structure.

[0014] 2. This differential and common mode integrated inductor with adjustable inductance can protect the magnetic sheet and reduce its damage by sliding it in the partition. On the other hand, it can support and fix the magnetic sheet to ensure reliable sliding of the magnetic sheet and improve the use effect.

[0015] The parts not involved in this device are the same as those in the prior art or can be implemented using the prior art. The utility model can push the magnetic sheet to both sides by tightening the screws, thereby adjusting the facing area and the upper and lower gaps between the upper and lower magnetic sheets, thereby adjusting the magnetic resistance of the magnetic sheet and the air magnetic resistance, thereby adjusting the magnetic resistance of the intermediate magnetic circuit to achieve the effect of adjusting the inductance, and the structure is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural diagram of a differential and common mode integrated inductor with adjustable inductance proposed by the utility model;

[0017] Figure 2 This is a structural schematic diagram of a differential and common mode integrated inductor separator with adjustable inductance proposed by the utility model;

[0018] Figure 3 This is a cross-sectional view of a differential and common mode integrated inductor separator with adjustable inductance proposed by the utility model;

[0019] Figure 4 This is a cross-sectional view of a differential and common mode integrated inductor with adjustable inductance proposed by the utility model. Figure 1 ;

[0020] Figure 5 This is a cross-sectional view of a differential and common mode integrated inductor with adjustable inductance proposed by the utility model. Figure 2 ;

[0021] Figure 6 This is a schematic diagram of a differential and common mode integrated inductor with adjustable inductance proposed by the utility model. Figure 1 ;

[0022] Figure 7 This is a schematic diagram of a differential and common mode integrated inductor with adjustable inductance proposed by the utility model. Figure 2 .

[0023] In the figure: 1. Closed magnetic core; 2. Coil winding; 3. Partition; 4. Magnetic sheet; 5. Screw. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0025] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0026] Example:

[0027] Reference Figure 1-Figure 7 , a differential common-mode integrated inductor with adjustable inductance, comprising a closed magnetic core 1, and two groups of coil windings 2 symmetrically wound on the closed magnetic core 1, and also comprising two groups of symmetrically distributed magnetic sheets 4, both of which are slidingly arranged in the closed magnetic core 1, and the sliding direction is parallel to the axial direction of the closed magnetic core 1, and the two groups of coil windings 2 are symmetrical about the middle surface of the two groups of magnetic sheets 4, and the material of the magnetic sheets 4 is a soft magnetic material, which can be ferrite, silicon steel, nickel-iron alloy or aerogel magnetic material, and an adjustment part for driving the magnetic sheets 4 to slide is provided in the closed magnetic core 1. When in use, the two groups of magnetic sheets 4 move away from or close to each other along the axis of the closed magnetic core 1, and the facing area and gap between the two groups of magnetic sheets 4 are adjusted to adjust the magnetic resistance of the intermediate magnetic circuit to achieve the effect of adjusting the inductance, and the structure is simple.

[0028] Reference Figure 1-Figure 4 Here, we design the adjustment part as follows: a partition 3 is provided in the closed magnetic core 1, and the two groups of magnetic pieces 4 are slidably set in the partition 3, and two groups of screws 5 are threaded on the partition 3, and one end of the two groups of screws 5 is respectively pressed against the opposite surfaces of the two groups of magnetic pieces 4. When in use, by adjusting the screws 5, the two groups of screws 5 can respectively drive the corresponding two groups of magnetic pieces 4 to move closer or farther away from each other, thereby adjusting the inductance, and the partition 3 has a protective and fixing effect. The material of the partition 3 is bakelite or plastic, preferably bakelite, which has excellent electrical insulation performance, heat resistance and mechanical strength. By tightening the screws 5, the magnetic piece 4 can be pushed to both sides, thereby adjusting the facing area and the upper and lower gaps of the upper and lower magnetic pieces 4, thereby adjusting the magnetic resistance of the magnetic piece 4 and the air magnetic resistance.

[0029] Reference Figure 3 and Figure 4 We make the two groups of magnetic sheets 4 into a right-angled trapezoidal structure, and make the surfaces where the oblique sides of the two groups of magnetic sheets 4 are adjacent surfaces, and place one end of the two groups of screws 5 against the short bottom sides of the two groups of magnetic sheets 4 respectively, so as to facilitate the adjustment of the facing area and gap between the two groups of magnetic sheets 4, so as to adjust the magnetic resistance of the middle magnetic circuit and thus achieve the purpose of adjusting the inductance.

[0030] An EMI filter includes a filter body, which includes an inductor, a capacitor, and a resistor connected in series or in parallel to form an anti-electromagnetic interference filter circuit network. The inductor adopts an integrated differential and common mode inductor with adjustable inductance. The above-mentioned integrated inductor can be used in various circuits such as filters and power supply circuits to simultaneously filter out or suppress common-mode and differential-mode noise interference in the circuit, and has a wide range of applications.

[0031] In the present invention, according to Ohm's law of magnetic circuit, magnetic resistance Rm=l / (μ*A), l represents the length of magnetic circuit, A represents the effective cross-sectional area of ​​magnetic circuit, μ represents the magnetic permeability of magnetic core, and the magnetic permeability of magnetic core is generally expressed as relative magnetic permeability μ r Indicates (μ r =μ / μ 0， relative to air); the magnetic permeability of air is μ0≈4π*10 -7 H / m.

[0032] Reference Figure 4 and Figure 5 , the upper and lower relative areas A1 of the two magnetic sheets 4 are D*B, and the relative gap is Lg. When the screws 5 push the magnetic sheets 4 to both sides, the relative width D of the two magnetic sheets 4 will decrease, and the relative area A1 will decrease; while the relative gap Lg will increase. It can be seen from the magnetic resistance formula that: if the numerator increases and the denominator decreases, the magnetic resistance Rm will increase. On the contrary, when the screws 5 are loosened and the magnetic sheets 4 on both sides are pushed together, the relative width D of the two magnetic sheets 4 will increase, and the relative area A1 will increase; while the relative gap Lg will decrease. It can be seen from the magnetic resistance formula that: if the numerator decreases and the denominator increases, the magnetic resistance Rm will decrease.

[0033] The calculation formula for inductance is L=N 2 / Rm, where N represents the number of coil turns and Rm represents the magnetic resistance of the magnetic circuit. If the number of turns remains unchanged and Rm increases, the inductance will decrease; conversely, if the number of turns remains unchanged and Rm decreases, the inductance will increase.

[0034] The principle of the differential and common mode integrated inductor is to use the leakage inductance of the common mode inductor as the differential mode inductor of the differential and common mode integrated inductor to achieve the integration of the differential and common mode integrated inductor.

[0035] The principle behind the leakage inductance of a common-mode inductor is that the common-mode inductor's leakage flux is the magnetic flux generated by N1 that doesn't pass through N2, forming a closed loop. When a differential-mode signal passes through the inductor, the leakage flux represents the net magnetic flux of the differential-mode inductor. The magnetic flux generated by the differential-mode inductor can be considered the leakage flux of the two coils. The greater the leakage flux, the greater the differential-mode inductor's differential-mode inductor.

[0036] Reference Figure 6When the common-mode signal passes through the differential common-mode integrated inductor, the magnetic resistance is large due to the air gap in the middle column, and the magnetic fluxes generated by the left and right coils N1 and N2 cancel each other out in the magnetic sheet 4. They are superimposed on each other in the magnetic circuit of the closed magnetic core 1 to resist the common-mode interference signal, so the magnetic fluxes of N1 and N2 will not pass through the magnetic sheet 4.

[0037] Reference Figure 7 When a differential-mode signal passes through the differential-common-mode integrated inductor, the magnetic flux generated by the left and right coils N1 and N2 does not cancel each other out at magnetic plate 4, but instead passes through it in the same direction. At this point, the closed magnetic core 1 has a low magnetic resistance and a long single magnetic path, while the magnetic path through magnetic plate 4 is short. However, due to the air gap, the magnetic resistance is large. The greater the magnetic resistance of the center column magnetic path, the smaller the magnetic flux passing through it, the smaller the leakage flux of the differential-common-mode inductor, and the smaller the differential-mode inductance of the differential-common-mode inductor. The smaller the air gap in the center column, the smaller the magnetic resistance of magnetic plate 4, the larger the magnetic flux passing through it, and the larger the differential-mode inductance of the differential-common-mode inductor. Therefore, the differential-mode inductance of the differential-common-mode integrated inductor can be adjusted by controlling the magnetic resistance of magnetic plate 4.

[0038] The above is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited to this. Any technician familiar with the technical field within the technical scope disclosed by the present invention can make equivalent replacements or changes based on the technical solution and utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A differential common mode integrated inductor with adjustable inductance, comprising a closed magnetic core (1), and two sets of coil windings (2) symmetrically wound around the closed magnetic core (1), characterized in that: The invention also includes two groups of symmetrically distributed magnetic sheets (4), both of which are slidably arranged in the closed magnetic core (1), the two groups of coil windings (2) are symmetrical about the middle planes of the two groups of magnetic sheets (4), and an adjustment portion for driving the magnetic sheets (4) to slide is provided in the closed magnetic core (1). When in use, the two groups of magnetic sheets (4) move away from or close to each other along the axis of the closed magnetic core (1).

2. The differential and common mode integrated inductor with adjustable inductance according to claim 1, characterized in that: The adjustment portion comprises a partition (3) arranged in the closed magnetic core (1), the two groups of magnetic sheets (4) are both slidably arranged in the partition (3), and two groups of screws (5) are threadedly connected to the partition (3), and one end of the two groups of screws (5) respectively abuts against the opposite surfaces of the two groups of magnetic sheets (4).

3. The differential and common mode integrated inductor with adjustable inductance according to claim 2, characterized in that: The two groups of magnetic sheets (4) are both in a right-angled trapezoidal structure, and the surfaces where the hypotenuses are located are adjacent surfaces. One end of the two groups of screws (5) respectively abuts against the short bottom edges of the two groups of magnetic sheets (4).

4. The differential and common mode integrated inductor with adjustable inductance according to claim 2, characterized in that: The partition (3) is made of bakelite.

5. The differential and common mode integrated inductor with adjustable inductance according to claim 1, characterized in that: The material of the magnetic sheet (4) is soft magnetic material.

6. An EMI filter, comprising a filter body, characterized in that: The filter body includes an inductor, a capacitor and a resistor connected in series or in parallel to form an anti-electromagnetic interference filter circuit network, and the inductor adopts the differential common mode integrated inductor with adjustable inductance according to any one of claims 1 to 5.

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