Power supply EMI filter

Abstract

The invention discloses a power supply EMI filter, relates to the technical field of power supply EMI filters, and aims to solve the problem that a power supply EMI filter in the prior art cannot meet the filtering requirement and is small in size. The power supply EMI filter comprises a shell, a circuit board and human pins, and the shell is provided with an accommodating cavity; the circuit board is arranged in the accommodating cavity; a common mode inductor and a capacitor are arranged on one side, far away from the bottom wall of the shell, of the circuit board; in the height direction of the shell, the orthographic projection of the capacitor on the circuit board is located in the orthographic projection of the common mode inductor on the circuit board, one end of the pin is connected with the circuit board, and the other end of the pin penetrates through the bottom wall of the shell and extends out of the shell.

Description

Technical Field

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

[0002] The current motor system usually adopts the drive system of pulse width modulation technology (PWM), which improves the controllability of motor operation and greatly improves the performance indicators. However, since the power electronic devices in the drive circuit module of the motor system work in the switching state, the power waveform on the switching device is discontinuous, so that the voltage and current contain complex high-order harmonics, which seriously "pollutes" the electromagnetic environment of the motor system and affects the normal operation of the electrical system. In order to reduce the interference of electromagnetic noise to the motor system, a power supply electromagnetic interference (EMI) filter is added to the motor system to optimize the electromagnetic environment in the motor system. The filtering characteristics of the power supply EMI filter are mainly determined by the frequency characteristics of the internal LC components.

[0003] In the related art, the LC element of the power supply EMI filter is reasonably designed so that the differential mode loss and common mode loss of the power supply EMI filter in a specific band meet the requirements. However, the power supply EMI filter is relatively large in size. Summary of the invention

[0004] The embodiment of the present application provides a power supply EMI filter, which is used to solve the problem that the power supply EMI filter in the related art cannot achieve both filtering requirements and small size.

[0005] An embodiment of the present application provides a power supply EMI filter, including a shell, a circuit board and a pin, wherein the shell has a accommodating cavity; the circuit board is arranged in the accommodating cavity; a common-mode inductor and a capacitor are arranged on a side of the circuit board away from the bottom wall of the shell; in the height direction of the shell, the orthographic projection of the capacitor on the circuit board is located within the orthographic projection of the common-mode inductor on the circuit board; one end of the pin is connected to the circuit board, and the other end is located outside the shell.

[0006] In some embodiments, the common-mode inductor includes a magnetic ring disposed on the circuit board and a winding wound on the magnetic ring, wherein the winding is electrically connected to the pin; in the height direction of the shell, the distance between the magnetic ring and the circuit board is greater than the height of the capacitor.

[0007] In some embodiments, the axial direction of the magnetic ring is parallel to the height direction of the shell.

[0008] In some embodiments, the magnetic ring is a solid structure; and / or, the material of the magnetic ring is manganese zinc material.

[0009] In some embodiments, the outline of the circuit board is square, the number of the pins is 4, the pins are located at the corners of the circuit board, and the capacitor is located between two adjacent pins.

[0010] In some embodiments, the capacitor includes two common-mode capacitors and two differential-mode capacitors, the two common-mode capacitors are located on opposite sides of the common-mode inductor along a first direction, and the two differential-mode capacitors are located on opposite sides of the common-mode inductor along a second direction, and the first direction, the second direction and the height direction of the shell are perpendicular to each other.

[0011] In some embodiments, the common-mode capacitor is a 1 μF chip capacitor with a rated voltage of 100 V; the differential-mode capacitor is a 10 μF chip capacitor with a rated voltage of 50 VDC.

[0012] In some embodiments, a ground pin is further provided on the circuit board, one end of the ground pin is electrically connected between the two common-mode capacitors, and the other end of the ground pin is located outside the housing.

[0013] In some embodiments, the operating frequency band of the power supply EMI filter is 150KHz to 30MHz.

[0014] In some embodiments, the shell has a cubic outline, a side length of the shell is 11 mm to 20 mm, and a height of the shell is 8 mm to 20 mm.

[0015] The power supply EMI filter provided in the embodiment of the present application is compared with the prior art. The power supply EMI filter in the present application sets the common-mode inductor and the capacitor on the same side of the circuit board. In this way, when the circuit board is installed, the circuit board can be as close to the bottom wall of the shell as possible, thereby reducing the distance between the circuit board and the bottom wall of the shell, shortening the length of the pin in the shell, and reducing the length of the pin when the length of the pin extending out of the shell is the same as the length of the pin in the related art, thereby saving costs; at the same time, in the height direction of the shell, the positive projection of the capacitor on the circuit board is located within the positive projection of the common-mode inductor on the circuit board, that is, the capacitor and the common-mode inductor are staggered in space and arranged on the circuit board. In this way, when the common-mode inductor and the capacitor have the same structure as in the related art, the area of ​​the circuit board is indirectly reduced, which is beneficial to improving the utilization rate of the housing cavity in the shell. In addition, the pin passes through the bottom wall of the shell and extends out of the shell, reducing the space occupied by the power supply EMI filter in the direction perpendicular to the height direction of the shell, thereby achieving the purpose of miniaturization of the power supply EMI filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of the internal structure of a power supply EMI filter in some embodiments of the present application at one viewing angle;

[0018] Figure 2 A schematic diagram of the internal structure of a power supply EMI filter in some embodiments of the present application from another perspective;

[0019] Figure 3 for Figure 1 A top view of the power supply EMI filter in FIG.

[0020] Figure 4 This is a schematic diagram of the assembly structure of common-mode inductors and capacitors on a circuit board in a power supply EMI filter in some embodiments of the present application;

[0021] Figure 5 A circuit schematic diagram of a power supply EMI filter in some embodiments of the present application;

[0022] Figure 6 for Figure 4 A schematic diagram of the structure of the top copper clad layer of the circuit board;

[0023] Figure 7 for Figure 4 A schematic diagram of the structure of the top solder paste layer of the circuit board in FIG.

[0024] Figure 8 for Figure 4 A schematic diagram of the structure of the top silk screen layer of the circuit board in FIG.

[0025] Fig. 9 for Figure 4 A schematic diagram of the structure of the bottom copper clad layer of the circuit board;

[0026] Fig.10 for Figure 4 A schematic diagram of the structure of the bottom soldering layer of the circuit board;

[0027] Fig.11 for Figure 4 A schematic diagram of the structure of the bottom silk screen layer of the circuit board;

[0028] Fig.12 It is a measured curve of common-mode insertion loss of the power supply EMI filter in some embodiments of the present application;

[0029] Fig.13 This is a measured curve of the differential mode insertion loss of the power supply EMI filter in some embodiments of the present application.

[0030] Description of reference numerals:

[0031] 1. Pin; 4. Capacitor;

[0032] 10. Shell; 101. Accommodating cavity; 11. Shell body; 12. Bottom plate; 13. Baffle;

[0033] 20. Circuit board; 201. Grounding hole; 21. Positive input; 22. Negative input; 23. Positive output; 24. Negative output; 25. Grounding pin;

[0034] 30. Common mode inductor; 31. Magnetic ring; 32. Winding; 321. First winding; 322. Second winding. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0037] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0038] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0039] The current motor system usually adopts the drive system of pulse width modulation technology (PWM), which improves the controllability of motor operation and greatly improves the performance indicators. However, since the power electronic devices in the drive circuit module of the motor system work in the switching state, the electric quantity waveform on the switching device is discontinuous, so that the voltage and current contain complex high-order harmonics, which seriously "pollutes" the electromagnetic environment of the motor system and affects the normal operation of the electrical system. In order to reduce the interference of electromagnetic noise on the motor system, a power supply EMI filter is added to the motor system to optimize the electromagnetic environment in the motor system. The filtering characteristics of the power supply EMI filter are mainly determined by the frequency characteristics of the internal LC components.

[0040] In the related art, the LC elements of the power supply EMI filter, such as common-mode inductors and capacitors, are arranged at intervals on the circuit, and the LC elements of the power supply EMI filter are reasonably designed so that the differential mode loss and common mode loss of the power supply EMI filter within a specific band meet the requirements.

[0041] Electromagnetic interference (EMI) refers to electromagnetic interference noise transmitted through power lines.

[0042] In order to solve the above problems, the present application provides a power supply EMI filter. The power supply EMI filter is matched with a DC motor switching power supply to meet the requirements of electromagnetic compatibility conducted emission. Since the power electronic switching frequency and its harmonics are the main sources of electromagnetic interference when the motor control system is working, the interference signal is transmitted to the subsequent circuit along the power line. In the frequency band of 10KHz to 30MHz, there are both low-frequency differential mode interference signals and high-frequency common mode interference signals. Therefore, when designing the structure of the power supply EMI filter circuit, it is necessary to fully consider strengthening the common and differential mode interference suppression capabilities at the same time.

[0043] like Figure 1 to Figure 3 As shown, the power EMI filter includes a housing 10, a circuit board 20 and a pin 1, the housing 10 has a receiving cavity 101; the circuit board 20 is arranged in the receiving cavity 101; the circuit board 20 is away from the bottom wall of the housing 10 ( Figure 1 A common-mode inductor 30 and a capacitor 4 are arranged on one side of the bottom plate 12 in the housing 10; in the height direction of the housing 10, the orthographic projection of the capacitor 4 on the circuit board 20 is located within the orthographic projection of the common-mode inductor 30 on the circuit board 20, one end of the pin 1 is connected to the circuit board 20, and the other end is located outside the housing 10. In other words, the common-mode inductor 30 and the capacitor 4 are staggered on the front side of the circuit board 20 (such as Figure 1 ), pin 1 is connected to the back side of the circuit board 20 (such as Figure 1The other end of the pin 1 passes through the bottom wall of the housing 10 and extends out of the housing 10. In this way, the back side of the circuit board 20 can be as close to the bottom wall of the housing 10 as possible.

[0044] The housing 10 is made of metal and has a closed accommodating cavity 101. The common mode inductor 30 and capacitor 4 are LC elements in the power EMI filter. The circuit board 20, the common mode inductor 30 and the capacitor 4 constitute a filter circuit of the power EMI filter.

[0045] There are four pins 1 , including an input positive electrode 21 , an input negative electrode 22 , an output positive electrode 23 and an output negative electrode 24 . The four pins 1 are electrically connected to the four connection terminals of the common mode inductor 30 in a one-to-one correspondence.

[0046] The orthographic projection of the capacitor 4 on the circuit board 20 is located within the orthographic projection of the common-mode inductor 30 on the circuit board 20, that is, the orthographic projection of the capacitor 4 on the circuit board 20 overlaps with the orthographic projection of the common-mode inductor 30 on the circuit board 20, including that part of the orthographic projection of the capacitor 4 on the circuit board 20 is located within the orthographic projection of the common-mode inductor 30 on the circuit board 20, and that the orthographic projection of the capacitor 4 on the circuit board 20 is entirely located within the orthographic projection of the common-mode inductor 30 on the circuit board 20, so that the capacitor 4 and the common-mode inductor 30 are staggered in the accommodating cavity 101 of the housing 10.

[0047] Compared with the related art in which a part of the multiple LC components are spaced on one side of the circuit board 20, for example, the common-mode inductor 30 is arranged on the front side of the circuit board 20, also called the top side, and another part of the LC components, such as the common-mode capacitor, is arranged on the other side of the circuit board 20, also called the bottom side, thereby reducing the area of ​​the circuit board 20, the power supply EMI filter in the present application arranges the common-mode inductor 30 and the capacitor 4 on the same side of the circuit board 20. In this way, when the circuit board 20 is installed, the circuit board 20 can be as close to the bottom wall of the housing 10 as possible, thereby not only reducing the distance between the circuit board 20 and the bottom wall of the housing 10, but also shortening the length of the pin 1 in the housing 10. When the length of the pin 1 extending out of the housing 10 is the same as the length of the pin 1 in the related art, the length of the pin 1 is reduced; Moreover, components are arranged on a single side of the circuit board 20, so that the circuit board 20 can adopt a single-sided board, thereby saving costs; at the same time, in the height direction of the shell 10, the positive projection part of the capacitor 4 on the circuit board 20 is located within the positive projection of the common-mode inductor 30 on the circuit board 20, that is, the capacitor 4 and the common-mode inductor 30 are staggered in space and arranged on the circuit board 20. In this way, when the common-mode inductor 30 and the capacitor 4 have the same structure as in the related art, the area of ​​the circuit board 20 is indirectly reduced, which is beneficial to improve the utilization rate of the storage cavity 101 in the shell 10. In addition, the pin 1 passes through the bottom wall of the shell 10 and extends out of the shell 10, reducing the space occupied by the power supply EMI filter in the direction perpendicular to the height direction of the shell 10, thereby achieving the purpose of miniaturization of the power supply EMI filter.

[0048] like Figure 1 As shown, the housing 10 includes a housing body 11 and a bottom plate 12, and the bottom plate 12 is sealed on the opening of the housing body 11 to form a closed accommodating cavity 101. Usually, the housing body 11 and the bottom plate 12 are made of metal, such as 10# steel, with a nickel-plated surface. The housing body 11 and the bottom plate 12 are usually welded, such as a parallel seam welding process, to improve the sealing of the housing 10, so that the power supply EMI filter can meet the environmental test requirements such as high and low temperature, humidity, and salt spray.

[0049] The pin 1 may be made of brass with a gold-plated outer layer to reduce the DC resistance of the product.

[0050] Of course, the pin 1 can also be made of copper clad with Kovar (also known as iron-nickel alloy) to achieve electrical connection with the circuit board 20. At the same time, the pin 1 and the housing 10 are insulated and sealed by an insulating member, such as a glass insulator.

[0051] It should be noted that the operating frequency band of the power supply EMI filter of the present application is 150KHz to 30MHz.

[0052] That is to say, the power supply EMI filter of the present application controls the differential mode loss and common mode loss of the power supply EMI filter within a reasonable range at 150KHz to 30MHz by reasonably designing the structures and parameters of the common mode inductor 30 and the capacitor 4.

[0053] like Figure 1 and Figure 3 As shown, the outer contour of the housing 10 is a cube, or approximately a cube.

[0054] The cube may be a rectangular parallelepiped or a cube. Hereinafter, a rectangular parallelepiped having a square cross section of the housing 10 perpendicular to the height direction is taken as an example for description.

[0055] The housing 10 is a rectangular parallelepiped, so in the design process of the circuit board 20, in order to improve the utilization rate of the space components in the accommodating cavity 101, the outline of the circuit board 20 is also square. When the outline shape of the housing 10 in the cross section of the height direction of the housing 10 changes, the outline of the circuit board 20 changes accordingly.

[0056] like Figure 3 As shown, the outline of the circuit board 20 is square, the number of pins 1 is 4, the pins 1 are located at the corners of the circuit board 20 , and the capacitor 4 is located between two adjacent pins 1 .

[0057] Since the common-mode inductor 30 is relatively large, by arranging the pin 1 at the corner of the circuit board 20 and setting the capacitor 4 between two adjacent pins 1, sufficient space is reserved for the common-mode inductor 30, which facilitates the design and installation of the common-mode inductor 30.

[0058] like Figure 1 and Figure 3 As shown, in some embodiments, the common-mode inductor 30 includes a magnetic ring 31 disposed on the circuit board 20 and a winding 32 wound on the magnetic ring 31, and the winding 32 is electrically connected to the pin 1; in the height direction of the shell 10, the distance between the magnetic ring 31 and the circuit board 20 is greater than the height of the capacitor 4.

[0059] The winding 32 includes a first winding 321 and a second winding 322 which are arranged at intervals. The first winding 321 has two connection ends, and the second winding 322 has two connection ends. The four connection ends of the winding 32 correspond to the four pins 1 one by one and are electrically connected.

[0060] Through the above arrangement, the common-mode inductor 30 and the capacitor 4 are staggered in space, which not only improves the space utilization in the accommodating cavity 101, thereby helping to reduce the volume of the shell 10, but also reduces the probability of interference between the common-mode inductor 30 and the capacitor 4.

[0061] like Figure 1 and Figure 3 As shown, in some embodiments, the axial direction of the magnetic ring 31 is parallel to the height direction of the housing 10. In other words, the magnetic ring 31 is arranged horizontally.

[0062] The magnetic ring 31 may be a solid structure, so that the volume of the magnetic ring 31 is reduced.

[0063] like Figure 4 and Figure 5 As shown, in some embodiments, capacitor 4 includes two common mode capacitors (such as Figure 4 C3 and C4 in the figure) and two differential mode capacitors (such as Figure 4 In the embodiment of the present invention, the two common-mode capacitors are located on opposite sides of the common-mode inductor 30 along the first direction, and the two differential-mode capacitors are located on opposite sides of the common-mode inductor 30 along the second direction. The first direction, the second direction and the height direction of the housing 10 are perpendicular to each other. In other words, the two common-mode capacitors and the two differential-mode capacitors are arranged on the four sides of the circuit board 20.

[0064] Through the above arrangement, not only the space of the circuit board 20 is fully utilized, but also the area of ​​the circuit board 20 is further reduced.

[0065] The common mode capacitor is a 1μF chip capacitor with a rated voltage of 100V; the differential mode capacitor is a 10μF chip capacitor with a rated voltage of 50VDC. In other words, the two common mode capacitors and the two differential mode capacitors are chip capacitors mounted on the circuit board 20. Since the integration of the chip capacitor is relatively high, it is not only convenient to assemble the capacitor with the circuit board 20, but also the capacitor and the common mode inductor 30 cooperate to form a power filter circuit to achieve a good filtering effect. The user can adjust the parameters of the two common mode capacitors and the two differential mode capacitors to make the power supply EMI filter meet the performance requirements.

[0066] The differential mode capacitor is 10μF, the rated voltage is 50VDC, the common mode capacitor is 1μF, the rated voltage is 100V, the common mode capacitors C3 and C4 are grounded, and the circuit schematic of the power supply EMI filter is as follows: Figure 5 shown.

[0067] The EMI filter circuit for the DC motor power supply of the present invention includes two parts: common mode filtering and differential mode filtering; the common mode filtering circuit includes a common mode inductor 30 ( Figure 5 L1 in the figure), positive line to ground common mode capacitor C3, negative line to ground common mode capacitor C4; the differential mode filter circuit includes a first differential mode capacitor Cl, a second differential mode capacitor C2, the first differential mode capacitor C1 is located at the front end as the front differential mode filter of the filter circuit, and the common mode inductor 30 ( Figure 5 After L1 in the figure, the second differential mode capacitor C2 is used as the post-stage differential mode filter.

[0068] Two differential mode capacitors, the first differential mode capacitor Cl and the second differential mode capacitor C2 use chip capacitors with larger capacity, which can better reflect the low-frequency differential mode signal interference between the lines to the input end. The chip capacitors with larger capacity are selected to widen the interference frequency band, thereby widening the frequency band range of the low-frequency differential mode signal interference and improving the filtering effect of the differential mode interference signal; two common mode capacitors, the positive line-to-ground common mode capacitor C3 and the negative line-to-ground common mode capacitor C4 use chip capacitors with smaller capacity, and at the same time, C3 and C4 are grounded to provide a ground bypass to bypass the common mode noise to ground. The above C3 and C4 can use passive LC devices, and use capacitors with small parasitic parameters and good electromagnetic characteristics at very high frequencies (that is, capacitors with small size, small parasitic parameters and high-frequency electromagnetic characteristics), and are surface-mounted on the circuit board 20 to achieve miniaturization and integration to ensure good electromagnetic compatibility characteristics. At the same time, a common mode inductor 30 is prepared by using a magnetic core made of a manganese-zinc material with high magnetic permeability, thereby improving the suppression effect and reducing the impact on the output.

[0069] like Figure 1 As shown, the circuit board 20 is also provided with a grounding pin 25, one end of which is electrically connected between the two common mode capacitors, and the other end of the grounding pin 25 is located outside the housing 10. A grounding mounting hole (not shown in the figure) is provided on the bottom plate 12, and a grounding hole 201 is provided on the circuit board 20, one end of the grounding pin 25 is electrically connected to the grounding hole 201, and the other end of the grounding pin 25 passes through the grounding mounting hole and extends outside the housing 10.

[0070] like Figure 2 As shown, a baffle 13 is protruded from the middle of the bottom side of the housing 10 so as to provide good support during installation and use.

[0071] In summary, in the embodiment of the present application, the minimum side length of the housing 10 of the power EMI filter can be 11 mm, and the minimum height of the housing 10 can be 8 mm.

[0072] Of course, on the basis that the performance of the power supply EMI filter meets the requirements, in addition to the outer dimensions of the shell 10, the side length of the shell 10 can also be any length of 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, and 20mm, and the height of the shell 10 can also be any length of 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, and 20mm, and no specific limitation is made here.

[0073] It should be noted that the outer dimensions of the housing 10 here do not include the dimensions of the baffle 13. During the design process of the baffle 13, the dimension of the baffle 13 in the height direction of the housing 10 is smaller than the length of the pin 1 extending out of the housing 10, so as to reduce the probability of interference between the baffle 13 and external devices during the installation of the power supply EMI filter.

[0074] The above-mentioned circuit board 20 includes copper cladding, soldering layer and silk screen printing in the preparation process. The structures of the top copper cladding layer, the top soldering layer and the top silk screen printing layer of the circuit board 20 are as follows: Figure 6 to Figure 8 As shown, the structures of the bottom copper clad layer, the bottom soldering layer and the bottom silk screen layer of the circuit board 20 are as shown in FIG. Figures 9 to 11 As shown in the figure. The top and bottom silk screen layers mainly serve as prompts to facilitate the connection of various components. Figure 6 to Figure 11 In the example, the corresponding relationship of the four pins 1 is given, such as Figure 4 The positive input 21 and Figure 6 and Fig. 9 The middle copper clad areas 21a and 21d, Figure 7 and Fig.10 The soldering assist areas 21b and 21e, and the silk screens 21c and 21f correspond to each other. Figure 4 The input negative electrode 2222, the output positive electrode 2323, the output negative electrode 2424 and so on.

[0075] The power supply EMI filter of the present invention, the circuit board 20, the common mode inductor 30 and the capacitor are assembled as shown in FIG. Figure 4 shown.

[0076] After actual measurement, the common mode insertion loss test curve is as follows: Fig.12 As shown, the differential mode insertion loss test curve is as follows Fig.13 shown. Fig.12 The horizontal axis is frequency (Hz), the vertical axis is decibel (dB), and the curve represents insertion loss; Fig.13 The horizontal axis is frequency (Hz), the vertical axis is decibel (dB), and the curve represents insertion loss; Fig.12 and Fig.13 It can be seen that the power supply EMI filter of the present invention has a common mode and differential mode insertion loss of more than 50 dB in the frequency band of 150 KHz to 30 MHz, and has good high-frequency filtering performance.

[0077] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A power supply EMI filter, characterized in that: include: A housing (10) having a receiving cavity (101); A circuit board (20) is arranged in the accommodating cavity (101); a common-mode inductor (30) and a capacitor (4) are arranged on a side of the circuit board (20) away from the bottom wall of the housing (10); in the height direction of the housing (10), an orthographic projection of the capacitor (4) on the circuit board (20) is located within an orthographic projection of the common-mode inductor (30) on the circuit board (20); A pin (1), one end of the pin (1) is connected to the circuit board (20), and the other end is located outside the housing (10).

2. The power supply EMI filter according to claim 1, characterized in that: The common-mode inductor (30) comprises a magnetic ring (31) arranged on the circuit board (20) and a winding (32) wound on the magnetic ring (31), wherein the winding (32) is electrically connected to the pin (1); In the height direction of the housing (10), the distance between the magnetic ring (31) and the circuit board (20) is greater than the height of the capacitor (4).

3. The power supply EMI filter according to claim 2, characterized in that: The axial direction of the magnetic ring (31) is parallel to the height direction of the shell (10).

4. The power supply EMI filter according to claim 2, characterized in that: The magnetic ring (31) is a solid structure; and / or the material of the magnetic ring (31) is manganese zinc material.

5. The power supply EMI filter according to claim 1, characterized in that: The outline of the circuit board (20) is square, the number of the pins (1) is four, the pins (1) are located at the corners of the circuit board (20), and the capacitor (4) is located between two adjacent pins (1).

6. The power supply EMI filter according to any one of claims 1 to 5, characterized in that: The capacitor (4) comprises two common-mode capacitors and two differential-mode capacitors, the two common-mode capacitors are located on two opposite sides of the common-mode inductor (30) along a first direction, and the two differential-mode capacitors are located on two opposite sides of the common-mode inductor (30) along a second direction, and the first direction, the second direction and the height direction of the housing (10) are perpendicular to each other.

7. The power supply EMI filter according to claim 6, characterized in that: The common mode capacitor is a 1 μF chip capacitor with a rated voltage of 100 V; the differential mode capacitor is a 10 μF chip capacitor with a rated voltage of 50 VDC.

8. The power supply EMI filter according to claim 6, characterized in that: The circuit board (20) is also provided with a ground pin (25), one end of the ground pin (25) is electrically connected between the two common-mode capacitors, and the other end of the ground pin (25) is located outside the housing (10).

9. The power supply EMI filter according to any one of claims 1 to 5, 7 and 8, characterized in that: The operating frequency band of the power supply EMI filter is 150KHz to 30MHz.

10. The power supply EMI filter according to any one of claims 1 to 5, 7 and 8, characterized in that: The shell (10) has a cubic outline, a side length of the shell (10) of 11 mm to 20 mm, and a height of the shell (10) of 8 mm to 20 mm.

Images