A high-voltage EMI filter

Abstract

The present invention discloses a high-voltage EMI filter, which includes a shielding housing, an inductor, a first capacitor, a second capacitor, a first insulating column and a second insulating column. The shielding housing includes a first shielding shell and a second shielding shell in a cylindrical shape. One end of the second shielding shell is fixedly connected to the first shielding shell, and the axis of the second shielding shell is perpendicular to the axis of the first shielding shell. The interiors of the first shielding shell and the second shielding shell are in communication; the first capacitor and the inductor are arranged in the first shielding shell, the second capacitor is arranged in the second shielding shell, both the first capacitor and the second capacitor are fixedly connected to the inductor, one end of the first insulating column extends into the first shielding shell and is fixedly connected to the first capacitor; one end of the second insulating column is fixedly connected to the second capacitor. The advantages are as follows: The high-voltage EMI filter can eliminate the resonance of the housing, ensure the realization of the insertion loss index within the working frequency band of the filter, and at the same time reduce the volume and weight of the filter, and lower the difficulty of manufacturing, installation and maintenance.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic compatibility, and in particular to a high-voltage EMI filter. Background Art

[0002] The 500-meter Aperture Spherical Telescope (FAST) is currently the world's largest single-aperture radio astronomy telescope. Since cosmic radio signals are so weak, in addition to being located in an area far from high electromagnetic radiation EMI pollution of human activities, it is also necessary to strictly shield and filter the power supply and distribution system that provides energy. The working frequency band of FAST is 70 MHz - 3 GHz. Although various modern electronic devices based on microprocessors have low power, they are rich sources of high-frequency interference. To avoid the leakage of these interferences, the shielding effectiveness of all distribution rooms needs to be increased to 90 - 100 dB, and all power frequency power lines (10 kV and 0.4 kV) entering and leaving the distribution rooms have to pass through power filters to filter out high-frequency interferences. The high-voltage filter works between the 10 kV phase line and the ground wire, and the steady-state voltage it withstands is 5.77 kV. Considering the possibility of power supply phase deviation, the rated voltage of the filter (i.e., the voltage that can be continuously withstood) is still specified as 10 kV. According to the above requirements, the technical indicators of the 10 kV high-voltage EMI filter are: rated voltage: 10 kV; rated current: two grades of 116 A and 46 A; leakage current: less than 35 mA @ 10 kV; insertion loss: greater than 90 dB @ 70 MHz - 3 GHz. Currently, such a product does not exist on the market.

[0003] The EMI filters of existing power supply lines generally have a voltage lower than 1 kV and use a square housing to accommodate internal components. When the working voltage reaches 10 kV, the volume and weight of the housing increase significantly, which brings difficulties to installation and maintenance, and the remaining space in the housing forms a resonant cavity, reducing the insertion loss of the filter at multiple resonant frequencies; in addition, the increase in the working voltage significantly reduces the reliability and service life of internal components. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-voltage EMI filter, thereby solving the foregoing problems existing in the prior art.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A high-voltage EMI filter includes a shielding housing, an inductor, a first capacitor, a second capacitor, a first insulating column, and a second insulating column. The shielding housing includes a first shielding shell and a second shielding shell in a cylindrical shape. One end of the second shielding shell is fixedly connected to the first shielding shell, and the axis of the second shielding shell is perpendicular to the axis of the first shielding shell. The interiors of the first shielding shell and the second shielding shell are in communication. The first capacitor and the inductor are disposed in the first shielding shell, the second capacitor is disposed in the second shielding shell, the first capacitor and the second capacitor are both fixedly connected to the inductor, and one end of the first insulating column extends into the first shielding shell and is fixedly connected to the first capacitor. One end of the second insulating column is fixedly connected to the second capacitor.

[0007] Preferably, the inductor includes a guide rod and multiple sets of magnetic ring groups sleeved on the outer periphery of the guide rod. Each of the magnetic ring groups is arranged in sequence along the axial direction of the guide rod. Each of the magnetic ring groups includes at least three magnetic rings coaxially arranged with the guide rod and sleeved from the inside to the outside along the radial direction of the guide rod.

[0008] Preferably, one end of the first shielding shell is hermetically arranged, and the other end is open. The second shielding shell is arranged at a position close to the sealed end of the first shielding shell.

[0009] Preferably, the first capacitor and the inductor are coaxially arranged with the first shielding shell. The first capacitor is fixed at one end of the inductor away from the sealed end. The first insulating column is coaxially arranged with the first shielding shell, and one end of the first insulating column extends into the first shielded shell from the open end of the first shielding shell and is fixedly connected to the first capacitor.

[0010] Preferably, the second capacitor is coaxially arranged with the second shielding shell. One end of the second insulating column extends into the interior of the second shielding shell through the end of the second shielding shell away from the first shielding shell and is fixedly connected to the second capacitor. One end of the second capacitor away from the second insulating column and one end of the inductor away from the first capacitor are fixedly connected through a connecting piece.

[0011] Preferably, the connecting piece is in an "L" shape. The connecting piece includes a first connecting side and a second connecting side. The first connecting side is perpendicular to the second connecting side. The first connecting side and the second connecting side are respectively perpendicular to the axes of the first shielding shell and the second shielding shell, and the first connecting side is fixedly connected to one end of the inductor away from the first capacitor. The second connecting side is fixedly connected to one end of the second capacitor away from the second insulating column.

[0012] Preferably, the insulating housing is made of stainless steel.

[0013] Preferably, insulating layers are provided on the inner walls of the first shielding case and the second shielding case, and the insulating layers are made of epoxy resin, polytetrafluoroethylene, PVC or silicone rubber.

[0014] Preferably, one end of the second insulating column is connected to a fastener through a flange, and the fastener extends into one end of the second shielding case away from the first shielding case and is fixedly connected to the second capacitor.

[0015] The beneficial effects of the present invention are as follows: The high-voltage EMI filter provided by the present invention consists of a highly reliable and long-life filtering circuit composed of ceramic capacitors and magnetic bead inductors, eliminates the resonance of the housing, ensures the realization of the insertion loss index within the operating frequency band of the filter, and simultaneously reduces the volume and weight of the filter, and reduces the difficulty of manufacturing, installation and maintenance. Description of the Drawings

[0016] Figure 1 is the front view of the high-voltage EMI filter in the embodiment of the present invention;

[0017] Figure 2 is the side view of the high-voltage EMI filter in the embodiment of the present invention;

[0018] Figure 3 is the cross-sectional view of the inductor in the embodiment of the present invention;

[0019] Figure 4 is the measured insertion loss result of the traditional large-box filter in the embodiment of the present invention;

[0020] Figure 5 is the measured insertion loss result of the high-voltage EMI filter in the embodiment of the present invention.

[0021] In the figure: 1. First shielding case; 2. Second shielding case; 3. First capacitor; 4. Second capacitor; 5. Inductor; 6. First insulating column; 7. Second insulating column; 8. Copper double-headed nut; 9. Flange; 10. Copper nut; 11. Connecting bolt; 12. Connector; 13. Step; 14. Guide rod; 15. First insulating sheath; 16. Inner ring magnetic ring; 17. Middle ring magnetic ring; 18. Outer ring magnetic ring; 19. Second insulating sheath. Detailed Embodiments

[0022] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] Embodiment 1

[0024] As Figures 1 to 3As shown in the figure, in this embodiment, a high-voltage EMI filter is provided, which includes a shielding housing, an inductor 5, a first capacitor 3, a second capacitor 4, a first insulating column 6, and a second insulating column 7. The shielding housing includes a first shielding shell 1 and a second shielding shell 2 in a cylindrical shape. One end of the second shielding shell 2 is fixedly connected to the first shielding shell 1, and the axis of the second shielding shell 2 is perpendicular to the axis of the first shielding shell 1. The interiors of the first shielding shell 1 and the second shielding shell 2 are in communication. The first capacitor 3 and the inductor 5 are arranged in the first shielding shell 1, the second capacitor 4 is arranged in the second shielding shell 2. The first capacitor 3 and the second capacitor 4 are both fixedly connected to the inductor 5. One end of the first insulating column 6 extends into the first shielding shell 1 and is fixedly connected to the first capacitor 3. One end of the second insulating column 7 is fixedly connected to the second capacitor 4.

[0025] In this embodiment, both the first capacitor 3 and the second capacitor 4 are ceramic capacitors. Generally, for high-frequency filters, feedthrough capacitors are generally selected to reduce the distributed inductance 5. In a voltage environment above 10 kV, ceramic capacitors or thin-film capacitors can be selected. Comparing the two, ceramic capacitors have a small volume, low internal resistance, long lifespan but small capacitance, while thin-film capacitors are the opposite. Considering from the perspectives of reliability and service life, ceramic capacitors are the optimal choice. Therefore, both the first capacitor 3 and the second capacitor 4 used in this embodiment are ceramic capacitors.

[0026] In this embodiment, the high-frequency filter generally uses a "feedthrough" bead inductor 5 to reduce the distributed capacitance. However, the inductance of a single-turn structure is very small. Coupled with the use of low-capacitance ceramic capacitors, to ensure the filter efficiency value, only by increasing the inductance 5 can it be compensated. Therefore, in this embodiment, to increase the inductance 5, two strategies of "lengthening" and "thickening" are adopted at the same time, making full use of the internal space to minimize the filter size to the greatest extent. "Lengthening" means that multiple sets of magnetic rings are arranged side by side and strung on a guide rod 14. "Thickening" means that each set of magnetic rings is nested and used with at least three layers of magnetic rings from the inside to the outside. And for the inner ring magnetic ring 16, a lower magnetic permeability is selected to avoid saturation. While for the outer ring, a high magnetic permeability is selected to make the main contribution to the inductance 5.

[0027] In this embodiment, the inductor 5 includes a guide rod 14 and multiple sets of magnetic ring groups sleeved on the outer periphery of the guide rod 14. Each of the magnetic ring groups is arranged in sequence along the axis direction of the guide rod 14. Each of the magnetic ring groups includes at least three magnetic rings coaxially arranged with the guide rod 14 and sleeved from the inside to the outside along the radial direction of the guide rod 14.

[0028] In this embodiment, the inductor 5 further includes a first insulating tube 15 and a second insulating tube 19. The first insulating tube 15 is coaxially sleeved on the outer periphery of the guide rod 14, and the second insulating tube 19 is coaxially sleeved on the outer periphery of the magnetic ring group with the guide rod 14. The three magnetic rings in each magnetic ring group are respectively an inner magnetic ring 16, a middle magnetic ring 17, and an outer magnetic ring 18.

[0029] In this embodiment, the insulating housing is made of stainless steel, that is, both the first shielding case 1 and the second shielding case 2 are made of stainless steel. One end of the first shielding case 1 is sealed, and the other end is open; the second shielding case 2 is arranged at a position close to the sealed end of the first shielding case 1.

[0030] In this embodiment, the small capacitance is compensated by a large inductance 5, so that the input impedance of the filter becomes larger. Then, because the input impedance of the input end is not low enough, the electromagnetic interference signal at the input end cannot be greatly suppressed at the first capacitor 3, and there is a relatively high interference signal voltage. In the filter housing of the traditional square structure, there is a lot of spatial coupling between the conductor of the input capacitor and the conductor of the filter output end, which causes a lot of interference to be coupled to the output end through space at medium and high frequencies, greatly reducing the filtering efficiency of the filter and not meeting the requirements. Therefore, the waveguide principle is adopted in this embodiment to solve this problem. The long metal circular tube (insulating housing) has the high-pass characteristic that high frequencies above the cut-off frequency can pass through, while low frequencies cannot pass through. Its cut-off frequency is 17.5 / D (GHz), where D is the diameter of the circular tube in cm.

[0031] In this embodiment, the first capacitor 3 and the inductor 5 are coaxially arranged with the first shielding case 1. The first capacitor 3 is fixed at one end of the inductor 5 away from the sealed end. The first insulating column 6 is coaxially arranged with the first shielding case 1, and one end of the first insulating column 6 extends into the first shielded case from the open end of the first shielding case 1 and is fixedly connected to the first capacitor 3.

[0032] In this embodiment, one end of the first shielding case 1 away from the second shielding case 2 is radially reduced to form a step 13. One end of the first insulating column 6 extends into the first shielding case 1 through this end and is fixedly connected to one end of the first capacitor 3 away from the inductor 5. A first mounting groove coaxial with it is arranged at one end of the first capacitor 3 away from the inductor 5, and a second mounting groove coaxial with it is arranged at one end of the first insulating column 6 close to the first capacitor 3. The two ends of the copper double-headed nut 8 are respectively inserted into the first mounting groove and the second mounting groove correspondingly to fixedly connect the first insulating column 6 and the first capacitor 3. And the outer wall of the first insulating column 6 is closely attached to the inner wall of the first shielding case 1 after the radial reduction at the end away from the second shielding case 2.

[0033] In this embodiment, a connecting bolt 11 is fixed to one end of the first insulating column 6 away from the first capacitor 3. When using a high-voltage EMI filter, the connecting bolt 11 can be used to connect other devices.

[0034] In this embodiment, a third mounting groove is provided at one end of the first capacitor 3 close to the inductor 5. One end of a copper double-headed nut 8 is fixedly connected to the guide rod 14 of the inductor 5, and the other end of the copper double-headed nut 8 is extended into the third mounting groove and fixedly connected to the first capacitor 3.

[0035] In this embodiment, the second capacitor 4 is coaxially arranged with the second shielding case 2. One end of the second insulating column 7 extends into the second shielding case 2 through the end of the second shielding case 2 away from the first shielding case 1 and is fixedly connected to the second capacitor 4. The end of the second capacitor 4 away from the second insulating column 7 and the end of the inductor 5 away from the first capacitor 3 are fixedly connected through a connecting member 12.

[0036] In this embodiment, a connecting bolt 11 is fixed to one end of the second insulating column 7 away from the second capacitor 4. When using a high-voltage EMI filter, the connecting bolt 11 can be used to connect other devices.

[0037] In this embodiment, one end of the second insulating column 7 is connected to a fastener through a flange 9. The fastener extends into the second shielding case 2 through the end of the second shielding case 2 away from the first shielding case 1 and is fixedly connected to the second capacitor 4. A fourth mounting groove is provided at the end of the second capacitor 4 away from the inductor 5, and a fifth mounting groove coaxial with it is provided at one end of the second insulating column 7 close to the second capacitor 4. The fastener is a copper double-headed nut 8, and both ends of the fastener extend into the fourth mounting groove and the fifth mounting groove respectively to fixedly connect the second insulating column 7 and the second capacitor 4.

[0038] In this embodiment, the connecting member 12 is in an "L" shape. The connecting member 12 includes a first connecting side and a second connecting side. The first connecting side is perpendicular to the second connecting side. The first connecting side and the second connecting side are respectively perpendicular to the axes of the first shielding case 1 and the second shielding case 2, and the first connecting side is fixedly connected to the end of the inductor 5 away from the first capacitor 3; the second connecting side is fixedly connected to the end of the second capacitor 4 away from the second insulating column 7.

[0039] In this embodiment, a first through hole is provided on the first connecting edge, and a copper nut 10 is used to pass through the first through hole to be fixedly connected to the inductor 5. A sixth mounting groove coaxial with the second capacitor 4 is provided at one end close to the inductor 5, and a second through hole is provided on the second connecting edge. A copper nut 10 is used to pass through the second through hole and extend into the sixth mounting groove to fix the second inductor 5 to the second connecting edge; that is, the inductor 5 is fixedly connected to the second capacitor 4 using the connecting piece 12 and the copper nut 10.

[0040] In this embodiment, an insulating layer is disposed on the inner walls of the first shielding shell 1 and the second shielding shell 2 , and the insulating layer is made of epoxy resin, polytetrafluoroethylene, PVC or silicone rubber.

[0041] In this embodiment, because the high-voltage EMI filter in this embodiment has a light and small structure, the electrical clearance and creepage distance are not abundant. Therefore, the following measures are taken in the manufacturing process of the high-voltage EMI filter to ensure the structural voltage resistance level; because most commonly used insulating materials such as epoxy resin, polytetrafluoroethylene, PVC, silicone rubber, etc. have a much higher resistance to puncture than air. Therefore, using them for insulating pads or potting can increase the creepage distance and block the discharge gap; that is, the insulating layer is made of epoxy resin, polytetrafluoroethylene, PVC, silicone rubber and other materials. In order to allow the high-voltage EMI filter to have a certain degree of non-destructive maintenance possibility, complete potting is not advocated except for the capacitor body. However, local paraffin potting of high-risk areas such as structural corners is very beneficial to improving the ability to resist high-voltage breakdown, and when dismantling and maintenance are required, only local paraffin needs to be melted.

[0042] Embodiment 2

[0043] like Figures 1 to 5 As shown, in this embodiment, during the development of the high-voltage EMI filter, taking the rated current 116A specification as an example, the filter capacitor is 5nf and the inductor is 12.5μH determined by theoretical calculation and microwave simulation. Among them, the through-hole ceramic capacitor is customized for the market, and the inductor magnetic ring adopts a mature product.

[0044] Capacitors: The main reason for the poor reliability and frequent failures of the high-voltage EMI filters produced in the early stage is the use of high-capacitance film capacitors. First, through reasonable parameter calculation, the capacitance requirement is reduced by 10 times, and ceramic capacitors with mature market, simple structure and reliable performance can be used.

[0045] Inductor 5: The consequence of reducing capacitance is the increase in inductor 5 demand. Therefore, this paper proposes to use nested magnetic rings to increase inductor 5 as much as possible within a limited space. High-voltage EMI filter inductor magnetic ring selection table (material nickel zinc)

[0046]

[0047] In this embodiment, each magnetic ring group uses three layers of magnetic rings. Because the closer to the conductor, the greater the magnetic field strength. High-permeability magnetic rings may enter the magnetic saturation region, which is not allowed. Because the permeability of saturated magnetic rings will almost drop to zero, just like air, completely losing the function of increasing the magnetic induction intensity. Therefore, magnetic rings made of low-permeability (below 40) materials are selected for the inner ring. Since the middle and outer rings are farther away from the current, medium (60 - 80) or high-permeability magnetic rings (100 - 200) can be selected, which will provide the main contribution to the inductance. The inner and outer rings are sleeved together, greatly reducing the length and outer diameter of the magnetic rings. The magnetic rings within the length of a 0.5-meter-long stainless steel tube enable the inductance of the 56A and 141A current filters to reach 22uH and 12uH respectively, meeting the requirements of filtering efficiency.

[0048] Shielding enclosure: At first, a square shell (1200Lx400Wx550H, traditional large box) was used for testing. It was found that although the bottom of the filter attenuation curve could reach 90dB, there were a large number of comb-shaped spikes below 1GHz. The top attenuation could only reach 30dB, as shown in Figure 4 . The shell was made as small as possible (inner diameter 110mm). To further reduce the path of spatial electromagnetic field coupling, at the same time, a slender steel tube (inner diameter 22mm, length 100mm) was used to block and isolate the internal space of the filter into two parts. If this slender tube is compared to a waveguide, its cut-off frequency can reach 8GHz, and the insertion loss is -140dB. The results prove that almost all coupling spikes are compressed to the maximum measurement ability of the instrument (-100dB or so) without adding a single stage (requiring additional capacitors). Thus, the insertion loss level of the high-voltage EMI filter basically meets the standard.

[0049] In this embodiment, an 11cm-inner-diameter stainless steel tube (outer diameter 114mm, wall thickness 2mm) is selected. It causes great attenuation to the spatial propagation of signals below the cut-off frequency of 1.59GHz. Especially when the length-diameter ratio of the circular tube reaches about 10, it will cause great "insertion loss" to the electromagnetic waves near and below the cut-off frequency passing through the inside, as shown in Figure 5 . Compared with Figure 4 and Figure 5 , the interference coupling from the input to the output end caused by cavity resonance in the traditional large box is significantly suppressed in the insulating enclosure of this embodiment and will not cause a decrease in insertion loss at specific frequencies.

[0050] Almost all existing filter housings are brazed, which is a simple and reliable method. In contrast, electromagnetic sealing methods such as threads and flanges 9 are not reliable and require many complicated and troublesome auxiliary measures. Stainless steel housings have the advantages of being strong, rust-resistant and standardized, but tin brazing is very difficult and has not yet been reported in filter manufacturing. We screened and tested a variety of fluxes and welding processes to solve the problem of stainless steel brazing. See the structural diagram, the filter has a total of three electromagnetic sealing welds. They are: 1-input capacitor ground ring and stainless steel housing welding, the purpose is to isolate the capacitor input cavity and the inductor 5 cavity; 2-output capacitor ground ring and stainless steel housing welding, the purpose is to isolate the inductor 5 cavity and the capacitor output cavity; 3-inductor 5 cavity is open to the outside, and the purpose of welding is to prevent interference electromagnetic fields and plane waves from leaking out. The appearance level of stainless steel brazing of high-voltage EMI filters has reached the same level as copper metal brazing.

[0051] The thickness of the insulation layer reaches several times the withstand voltage requirement to ensure that no penetration breakdown occurs. Usually, epoxy resin, polytetrafluoroethylene or PVC materials with a thickness of 3-5mm meet the requirements. Through epoxy or silicone rubber bonding of the insulating bushing joint gap, the "insulator surface" becomes the "inside" of the insulator, thereby cutting off the path of surface creepage. Local potting (epoxy, silicone rubber, paraffin, etc.) measures are adopted for local high-risk areas (tail three-way parts). The use of bushings and local potting measures not only achieves the withstand voltage performance, but also greatly reduces the cost and weight compared to complete potting and improves the maintainability of the filter. If necessary, the internal components may be disassembled and replaced. After 30 days of continuous testing with a high voltage of 10KV, there is no obvious discharge, leakage, creepage, etc. This shows that the structural safety of the high-voltage EMI filter can meet the use of 10KV high-voltage occasions.

[0052] By adopting the above technical solution disclosed in the present invention, the following beneficial effects are obtained:

[0053] The invention discloses a high-voltage EMI filter, which is a high-reliability and long-life filter circuit composed of a ceramic capacitor and a magnetic bead inductor, and eliminates the resonance of a shell, thereby ensuring the realization of the insertion loss index of the filter within the working frequency band, while reducing the volume and weight of the filter and reducing the difficulty of manufacturing, installation and maintenance.

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be considered as the scope of protection of the present invention.

Claims

1. A high-voltage EMI filter, characterized in that: it includes a shielding housing, an inductor, a first capacitor, a second capacitor, a first insulating column and a second insulating column. The shielding housing includes a first shielding shell and a second shielding shell in a cylindrical shape. One end of the second shielding shell is fixedly connected to the first shielding shell, and the axis of the second shielding shell is perpendicular to the axis of the first shielding shell. The interiors of the first shielding shell and the second shielding shell are in communication; the first capacitor and the inductor are arranged in the first shielding shell, the second capacitor is arranged in the second shielding shell, both the first capacitor and the second capacitor are fixedly connected to the inductor, and one end of the first insulating column extends into the first shielding shell to be fixedly connected to the first capacitor; one end of the second insulating column is fixedly connected to the second capacitor; the inductor includes a guide rod and multiple sets of magnetic ring groups sleeved on the outer periphery of the guide rod. Each of the magnetic ring groups is arranged in sequence along the axial direction of the guide rod; each of the magnetic ring groups includes at least three magnetic rings coaxially arranged with the guide rod and sleeved from the inside to the outside along the radial direction of the guide rod; the inductor further includes a first insulating protective tube and a second insulating protective tube. The first insulating protective tube is coaxially sleeved on the outer periphery of the guide rod, and the second insulating protective tube is coaxially sleeved on the outer periphery of the magnetic ring groups; one end of the first shielding shell is hermetically arranged, and the other end is open; the second shielding shell is arranged at a position close to the sealed end of the first shielding shell.

2. The high-voltage EMI filter according to claim 1, characterized in that: the first capacitor and the inductor are coaxially arranged with the first shielding shell. The first capacitor is fixed at one end of the inductor away from the sealed end. The first insulating column is coaxially arranged with the first shielding shell, and one end of the first insulating column extends into the first shielding shell from the open end of the first shielding shell to be fixedly connected to the first capacitor.

3. The high-voltage EMI filter according to claim 2, characterized in that: the second capacitor is coaxially arranged with the second shielding shell. One end of the second insulating column extends into the interior of the second shielding shell through the end of the second shielding shell away from the first shielding shell to be fixedly connected to the second capacitor. One end of the second capacitor away from the second insulating column and one end of the inductor away from the first capacitor are fixedly connected through a connecting member.

4. The high-voltage EMI filter according to claim 3, characterized in that: the connecting member is in an "L" shape. The connecting member includes a first connecting side and a second connecting side. The first connecting side is perpendicular to the second connecting side. The first connecting side and the second connecting side are respectively perpendicular to the axes of the first shielding shell and the second shielding shell, and the first connecting side is fixedly connected to one end of the inductor away from the first capacitor; the second connecting side is fixedly connected to one end of the second capacitor away from the second insulating column.

5. The high-voltage EMI filter according to claim 1, characterized in that: the shielding housing is made of stainless steel.

6. The high-voltage EMI filter according to claim 5, characterized in that: Insulation layers are provided on the inner walls of the first shielding case and the second shielding case, and the insulation layer is made of epoxy resin, polytetrafluoroethylene, PVC or silicone rubber.

7. The high-voltage EMI filter according to claim 6, characterized in that: One end of the second insulating column is connected to a fastener through a flange, and the fastener extends into one end of the second shielding case away from the first shielding case and is fixedly connected to the second capacitor.

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