CN219181493U

CN219181493U - Filter

Info

Publication number: CN219181493U
Application number: CN202223504927.8U
Authority: CN
Inventors: 陈思宇; 吴操
Original assignee: Chengdu Qiwei Technology Co ltd
Current assignee: Chengdu Qiwei Technology Co ltd
Priority date: 2022-12-28
Filing date: 2022-12-28
Publication date: 2023-06-13
Anticipated expiration: 2032-12-28

Abstract

The utility model relates to the technical field of filters, in particular to a filter, which comprises a shell, a filter component and a cover plate, wherein the filter component is arranged in the shell, the cover plate is arranged above the filter component and forms a closed structure with the shell, the filter component comprises a circuit board, a capacitor and an inductor, the capacitor and the inductor are connected to form a filter circuit and then are arranged on the top layer of the circuit board, the capacitor comprises a plurality of small-capacity parallel line ground common-mode capacitors and a plurality of small-capacity parallel line-to-line differential mode filter capacitors, the inductor comprises a double-wire parallel winding common-mode inductor, and compared with a capacitor with a large capacity, the capacitor has the advantages of small high-frequency impedance and good high-frequency filter effect.

Description

Filter

Technical Field

The utility model relates to the technical field of filters, in particular to a filter.

Background

In order to meet the electromagnetic compatibility requirements of the devices, various filters have been developed. The index parameter showing the filter performance is an insertion loss value, and the higher the insertion loss value is, the better the filter performance of the filter is. And improving the high-frequency band insertion loss value of the filter is a pursuit target of filter design. At present, the existing filter generally adopts a single filter capacitor with a large capacitance to carry out differential mode filtering, and the resonance frequency point of the single filter capacitor with a large capacitance is lower, so that the high-frequency filtering effect is reduced. Meanwhile, the common mode inductance of the filter device used in the existing filter is generally wound in a mode of winding the components by winding the edges and adding the partition plates in the middle, and the winding mode increases the distributed capacitance, so that the high-frequency filtering effect is reduced.

Disclosure of Invention

The utility model provides a filter for improving high-frequency filtering effect, which aims to solve the problems that in a grounding mode, grounding impedance and grounding lead inductance are larger, single large-capacity filtering capacitor is large in ESL (electronic stability program) and low in resonant frequency, high-frequency impedance is increased, turn-to-turn winding distance in a split winding mode is closer, and filtering effect is reduced due to reduction of high-frequency impedance of the filtering inductor caused by larger distributed capacitance.

The utility model is realized by the following technical scheme:

the utility model provides a wave filter, includes casing, filter element and apron, filter element installs in the casing, the apron sets up in filter element top and constitutes closed structure with the casing, filter element includes circuit board, electric capacity and inductance are connected and are set up in the circuit board top layer after constituting filter circuit, electric capacity includes many little appearance value parallel ground common mode electric capacity, many little appearance value parallel line-to-line differential mode filter electric capacity, the inductance includes double-line parallel winding type common mode inductance.

Further, the bottom layer of the circuit board of the filtering component is attached to the inner wall of the shell.

Furthermore, the bottom layer of the circuit board of the filter component is copper-coated and grounded, and the bottom layer is entirely coated with copper-coated and grounded network, and is entirely windowed and tin-coated after copper coating.

Further, the shell is a rectangular shell, and through holes for fixing the grounding fastening screws are respectively formed in four corners of the shell.

Further, the line-to-ground common mode capacitor comprises a capacitor CY1, a capacitor CY2, a capacitor CY3, a capacitor CY4, a capacitor CY5, a capacitor CY6, a capacitor CY7, a capacitor CY8, a capacitor CY11, a capacitor CY12, a capacitor CY13, a capacitor CY14, a capacitor CY15, a capacitor CY16, a capacitor CY17 and a capacitor CY18, and the line-to-line differential mode filter capacitor comprises a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7 and a capacitor C8.

Further, one end of the capacitor CY1 is respectively connected with one end of the capacitor CY2, one end of the capacitor CY3, one end of the capacitor CY4, one end of the capacitor CY5, one end of the capacitor CY6, one end of the capacitor CY7, one end of the capacitor CY8 and then grounded FG, the other end of the capacitor CY1 is respectively connected with the other end of the capacitor CY2, the other end of the capacitor CY3, the other end of the capacitor CY4, one end of the capacitor C1, one end of the capacitor C2, one end of the capacitor C3 and the input end 2 of the common-mode inductor LF1, and the other end of the capacitor CY5 is respectively connected with the other end of the capacitor CY6, the other end of the capacitor CY7, the other end of the capacitor CY8, the other end of the capacitor C1, the other end of the capacitor C2, the other end of the capacitor C3 and the input end 2 of the common-mode inductor LF1 and then grounded GND.

Further, the output end 3 of the common-mode inductor LF1 is connected to one end of the magnetic core inductor L1, the other end of the magnetic core inductor L1 is connected to one end of the capacitor C5, one end of the capacitor C6, one end of the capacitor C7, one end of the capacitor C8, one end of the capacitor CY15, one end of the capacitor CY16, one end of the capacitor CY17, the other end of the capacitor CY18, one end of the capacitor CY11, one end of the capacitor CY12, one end of the capacitor CY13, one end of the capacitor CY14, and then grounded FG, the other end of the capacitor CY11 is connected to the other end of the capacitor CY12, the other end of the capacitor CY13, the other end of the capacitor CY14, the other end of the capacitor C5, the other end of the capacitor C6, the other end of the capacitor C7, the other end of the capacitor C8, one end of the magnetic core inductor L2, and then grounded GND, and the other end of the magnetic core inductor L2 is connected to the output end 4 of the common-mode inductor LF 1.

Further, the input positive end, the input negative end, the output positive end and the output negative end of the filter circuit are respectively connected with the shell through wires.

The utility model has the beneficial effects that:

(1) According to the filter provided by the utility model, a large-area copper-clad grounding mode is adopted, so that the grounding area is increased, the grounding impedance is reduced, and the high-frequency filtering effect is improved compared with a screw grounding mode;

(2) Compared with the grounding mode of a device pin welding shell, the grounding mode of the large-area copper-clad grounding mode adopted by the filter reduces the inductance of a grounding lead and improves the high-frequency filtering effect;

(3) Compared with the split winding common-mode inductance, the filter provided by the utility model has the advantages that the distributed capacitance is small, the high-frequency common-mode impedance is large, and the high-frequency filtering effect is good;

(4) The filter provided by the utility model adopts a parallel filtering mode of a plurality of small capacitors, and compared with a capacitor with a large capacitance, the filter has the advantages of small high-frequency impedance and good high-frequency filtering effect.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed in the description of the embodiments will be briefly described below, it will be apparent that the drawings in the following description are only some embodiments of the present utility model, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a top view of a filter according to an embodiment of the present utility model;

FIG. 2 is a side cross-sectional view of a filter according to an embodiment of the present utility model;

FIG. 3 is a top cross-sectional view of a filter according to an embodiment of the present utility model;

FIG. 4 is an exploded view of a filter according to an embodiment of the present utility model;

fig. 5 is a schematic diagram illustrating a grounding of a screw lock of a filter according to an embodiment of the present utility model;

FIG. 6 is a schematic diagram of a filter circuit of a filter according to an embodiment of the present utility model;

FIG. 7 is a graph showing the impedance versus frequency according to an embodiment of the present utility model;

FIG. 8 is a diagram of a high frequency equivalent model of an inductor according to an embodiment of the present utility model;

in the figure, the common mode inductance of 1-double-wire parallel winding type, the common mode capacitance of 2-multiple small-capacity parallel lines, the differential mode filter capacitance between 3-multiple small-capacity parallel lines, the 4-cover plate, the 5-filter component, the 6-shell and the 7-grounding fastening screw are arranged.

Detailed Description

For the purpose of making apparent the objects, technical solutions and advantages of the present utility model, the present utility model will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present utility model and the descriptions thereof are for illustrating the present utility model only and are not to be construed as limiting the present utility model.

Example 1

The embodiment provides a grounding mode structure of a filter.

The existing filter adopts a mode of placing a grounding pad on a printed board, and after the printed board is fastened by a screw, the printed board and the shell are well grounded. The grounding mode has small grounding area and is based on the law of resistance

Resistance->

In inverse proportion to the ground area, the larger the ground area, the smaller the impedance. Therefore, the grounding mode has larger grounding impedance and grounding lead inductance, which can reduce the high-frequency filtering effect.

Referring to fig. 1-4, the grounding mode of the filtering component in the scheme adopts large-area copper rear window tin spraying, the filtering component is welded on the shell through reflow soldering, and the filtering component is welded on the shell according to a resistance formula

It can be seen that the resistance +.>

In inverse proportion to the contact area,the larger the contact area, the smaller the ground resistance.

Example 2

The embodiment provides a filter element connection mode of a filter.

The existing filter adopts a filter capacitor with a direct-insert lead, and the lead length of a component pin is introduced in the mode of directly welding the component lead with the shell, so that the lead inductance is increased, the high-frequency insertion loss value is reduced, and the high-frequency filtering effect is reduced;

referring to fig. 1-4, in the present solution, the direct welding of the filter element pins to the housing ground introduces a device pin length inductance, the pin length inductance is 1nH/mm, and assuming that the length of the single-side ground lead is 20mm, the leads on both sides will introduce an inductance value of 40nH in total.

Example 3

The embodiment provides a filter circuit connection structure of a filter.

The existing filter adopts a single large-capacity filter capacitor as a filter device, and as the ESL equivalent series inductance of the single large-capacity filter capacitor is large and the resonance frequency is low, the high-frequency impedance is increased, and the filtering effect is reduced;

referring to fig. 1-4, the filter circuit line-to-line and line-to-ground capacitors in the scheme are all formed by connecting a plurality of filter capacitors with small capacitance in parallel, and then the filter capacitors with large capacitance are replaced, so that the self-resonance frequency point is improved, the high-frequency impedance of the filter capacitors is reduced, and the high-frequency filtering effect is improved. The impedance versus frequency graph of the capacitors with different capacitance values is shown in fig. 7. As can be seen from fig. 7, the capacitance impedance of the small capacitance value is smaller than the impedance of the large capacitance value after the self-resonance frequency, so that the high-frequency filtering effect of the small capacitance value is better than that of the large capacitance value, but the capacitance impedance of the large capacitance value is smaller than that of the small capacitance value before the self-resonance frequency, so that in order to reduce the low-frequency impedance and improve the low-frequency filtering effect, a plurality of small capacitance values of the capacitors are adopted in the scheme to be connected in parallel.

Example 4

The embodiment provides an inductance of a filter.

The existing filter adoptsThe common mode filter inductance mode is wound by the split edges, and the interlayer distributed capacitance is increased. According to the capacitance formula

The capacitance is inversely proportional to the distance between the capacitance pole plates, the closer the distance between the pole plates is, the larger the capacitance is, the closer the distance between turn windings in the split winding mode is, and the distributed capacitance is larger. The high-frequency impedance of the filtering inductor is reduced, and the filtering effect is reduced;

referring to fig. 1-4, the common mode filter inductor adopting the double-wire parallel winding mode is characterized in that the winding turn-to-turn relative distance is far compared with the common mode inductor wound by split edges, and according to a capacitance formula:

it can be seen that the relative distance +.>

The larger the capacitance is, the smaller the capacitance value is, according to LC parallel resonance formula: />

And inductance high frequency equivalent model fig. 8 shows that when the common mode inductance is +.>

、/>

Timing, add->

The smaller the parallel resonance frequency, the larger the impedance at high frequency, and the larger the attenuation of the common mode disturbance current. Therefore, the double-wire parallel winding common-mode inductor can reduce the distributed capacitance value, improve the resonance frequency point, increase the high-frequency impedance and optimize the high-frequency filtering effect.

Example 5

The present embodiment proposes a schematic circuit diagram of a filter.

Referring to fig. 6, differential mode filter capacitors among C1, C2, C3, C5, C6, C7 and C8 adopt a plurality of capacitors with small capacitance values to be connected in parallel to replace a traditional filter capacitor with large capacitance value, and common mode capacitors among CY1 to CY8 and CY11 to CY18 adopt a plurality of capacitors with small capacitance values to be connected in parallel to replace a traditional filter capacitor with large capacitance value.

The foregoing has shown and described the basic principles and main features of the present utility model and the advantages of the present utility model. It will be understood by those skilled in the art that the present utility model is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present utility model, and various changes and modifications may be made without departing from the spirit and scope of the utility model, which is defined in the appended claims. The scope of the utility model is defined by the appended claims and equivalents thereof.

Claims

1. The utility model provides a wave filter, its characterized in that includes casing, filter component and apron, filter component installs in the casing, the apron sets up in filter component top and constitutes closed architecture with the casing, filter component includes circuit board, electric capacity and inductance are connected and are set up in the circuit board top layer after constituting filter circuit, electric capacity includes many little capacitance and the common mode electric capacity of line ground, many little capacitance parallel line interline differential mode filter electric capacity, the inductance includes double-line parallel winding type common mode inductance.

2. A filter according to claim 1, wherein the bottom layer of the circuit board of the filter member is attached to the inner wall of the housing.

3. A filter according to claim 1, wherein the circuit board substrate of the filter element is copper-clad grounded.

4. A filter according to claim 1, wherein the housing is a rectangular housing, and four corners of the housing are respectively provided with through holes for fixing ground fastening screws.

5. The filter according to claim 1, wherein the line-to-ground common mode capacitor comprises a capacitor CY1, a capacitor CY2, a capacitor CY3, a capacitor CY4, a capacitor CY5, a capacitor CY6, a capacitor CY7, a capacitor CY8, a capacitor CY11, a capacitor CY12, a capacitor CY13, a capacitor CY14, a capacitor CY15, a capacitor CY16, a capacitor CY17 and a capacitor CY18, the line-to-ground common mode filter capacitor comprises a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7 and a capacitor C8, one end of the capacitor CY1 is connected to one end of the capacitor CY2, one end of the capacitor CY3, one end of the capacitor CY4, one end of the capacitor CY5, one end of the capacitor CY6, one end of the capacitor CY7, one end of the capacitor CY8, and then the capacitor FG are grounded, the other end of the capacitor CY1 is connected to the other end of the capacitor CY2, the other end of the capacitor CY3, the other end of the capacitor CY4, the other end of the capacitor C1, the capacitor C2, the capacitor C3, the capacitor C6, the common mode filter capacitor C1 and the other end of the capacitor C2 are connected to the other end of the capacitor C1, and the other end of the capacitor C2.

6. The filter according to claim 5, wherein the output end 3 of the common-mode inductor LF1 is connected to one end of the magnetic core inductor L1, the other end of the magnetic core inductor L1 is connected to one end of the capacitor C5, one end of the capacitor C6, one end of the capacitor C7, one end of the capacitor C8, one end of the capacitor CY15, one end of the capacitor CY16, one end of the capacitor CY17, one end of the capacitor CY18, one end of the capacitor CY11, one end of the capacitor CY12, one end of the capacitor CY13, one end of the capacitor CY14, and then grounded FG, the other end of the capacitor CY11 is connected to one end of the capacitor CY12, one end of the capacitor CY13, one end of the capacitor CY14, one end of the capacitor C5, one end of the capacitor C6, one end of the capacitor C7, one end of the capacitor C8, one end of the magnetic core inductor L2, and then grounded GND, and the other end of the magnetic core inductor L2 is connected to the output end 4 of the common-mode inductor LF 1.

7. The filter of claim 1, wherein the filter circuit has an input positive terminal, an input negative terminal, an output positive terminal, and an output negative terminal, respectively, connected to the housing by wires.