EMI power filter with insulation protection mechanism

Abstract

This invention discloses an EMI power filter with an insulation protection mechanism, comprising a filter structure and a first impedance mismatch network structure and a second impedance mismatch network structure. The first impedance mismatch network structure includes an L mismatch network, a C mismatch network, and a switching switch. The switching switch is used to switch the connection state of the L mismatch network and the C mismatch network with the filter structure. The filter structure includes a multi-stage common-mode filter module. An insulation protection mechanism is provided on the circuit board. An insulating base is used to fix the circuit board to the first common-mode inductor. An insulating protective cover is fitted outside the inductor coil to isolate the multi-stage common-mode filter module. This invention uses an insulation protection mechanism to isolate the multi-stage common-mode filter modules from each other, thereby increasing the number of filtering stages while reducing the size of the power filter. Simultaneously, the switching switch allows for switching of the mismatch networks, increasing the filter's applicability while minimizing its size.

Description

Technical Field

[0001] This invention relates to the field of EMI power filter technology, specifically to an EMI power filter with an insulation protection mechanism. Background Technology

[0002] With the promotion and application of new energy vehicles across provinces and cities nationwide, the construction of charging infrastructure for new energy vehicles is also being advanced at the provincial and municipal levels. Electric vehicle motor controllers and the entire vehicle must meet the mandatory national standards (GB / T 18387-2008 and GB14023-2011). Switching devices in the electric vehicle's motor drive system generate large-amplitude steep pulses during rapid switching on and off, resulting in wide-bandwidth and high-energy electromagnetic interference (EMI), which is a major source of interference for the electric drive system. If the generated noise is not suppressed, its common-mode noise will be conducted to sensitive equipment, damaging the electric vehicle's power supply and affecting its lifespan. Therefore, appropriate power filters are needed for the motor drive system, motor controller, and load systems such as air conditioning in new energy vehicles to filter out EMI and ensure their normal operation. Currently, OEMs and component manufacturers are designing and developing related EMI filter products. However, vehicle power filters require small size and vibration resistance. Therefore, due to the limitations of their application scenarios, there is currently no product that can minimize the size of the power filter while improving its filtering stability and applicability. Summary of the Invention

[0003] The purpose of this invention is to provide an EMI power filter with an insulation protection mechanism. By setting the insulation protection mechanism to isolate the multi-stage common-mode filter modules from each other, the overall structure of the filter can be kept small and the filtering effect can be good, so that the EMI power filter can be reliably applied to noise sources and noise loads with different high and low impedances.

[0004] To achieve the above objectives, the present invention provides the following technical solution: an EMI power filter with an insulation protection mechanism, the EMI power filter comprising a filter structure and a first impedance mismatch network structure and a second impedance mismatch network structure respectively connected to the input and output ends of the filter structure, the first impedance mismatch network structure and the second impedance mismatch network structure having the same structure, the first impedance mismatch network structure comprising an L mismatch network, a C mismatch network and a switching switch, the switching switch being used to switch the connection state of the L mismatch network and the C mismatch network with the filter structure; the filter structure comprising a common-mode filter component, the common-mode filter component comprising a multi-stage common-mode filter module, the common-mode filter module comprising a first common-mode inductor, a first common-mode capacitor and a circuit board, the circuit board being provided with an insulation protection mechanism, the insulation protection mechanism comprising an insulating base and an insulating protective cover connected to the top of the insulating base, the insulating base being used to fix the circuit board to the first common-mode inductor, the insulating protective cover being sleeved on the outside of the inductor coil, being used to isolate the multi-stage common-mode filter module.

[0005] Preferably, the switching switch includes a fixed end, a first connecting piece, and a second connecting piece. One end of each of the first and second connecting pieces is rotatably connected to the fixed end. The switching switch includes a first state and a second state. When the switching switch is in the first state, the first and second connecting pieces connect the L mismatch network to the filter structure, and the C mismatch network is disconnected from the filter structure. When the switching switch is in the second state, the first and second connecting pieces connect the C mismatch network to the filter structure, and the L mismatch network is disconnected from the filter structure.

[0006] Preferably, the L mismatch network includes a first resistor R1 and a first inductor L1. One end of the first inductor L1 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is connected to a fixed terminal. When the switch is in the first state, the other end of the first inductor L1 is connected to a first connecting piece, and the second connecting piece is connected to the filter structure. The C mismatch network includes a first capacitor C1. One end of the first capacitor C1 is grounded. When the switch is in the second state, the other end of the first capacitor C1 is connected to a second connecting piece, and the first connecting piece is connected to the filter structure.

[0007] Preferably, the filter structure further includes a differential-mode filter. The input terminal of the common-mode filter component is connected to the output terminal of the first impedance mismatch network structure, the output terminal of the common-mode filter component is connected to the input terminal of the differential-mode filter, and the output terminal of the differential-mode filter is connected to the input terminal of the second impedance mismatch network structure. The circuit board includes an insulating surface and a conductive surface. The first common-mode inductor is mounted on the insulating surface of the circuit board. The first common-mode inductor includes a rectangular magnetic core and a first coil and a second coil that are parallel to each other on the magnetic core. The first common-mode capacitor is mounted on one side of the conductive surface of the circuit board. The first common-mode capacitor includes a second capacitor and a third capacitor connected in series. The other ends of the second capacitor and the third capacitor are connected to an elastic conductive sheet. One end of the first coil and the second coil passes through the circuit board and is connected to the other end of the second capacitor and the third capacitor, respectively.

[0008] Preferably, two elastic conductive sheets are provided, with one end of each elastic conductive sheet fixedly mounted on one end of the second capacitor and the third capacitor, respectively. The elastic conductive sheet is configured with an arc-shaped structure, and its arc-shaped protrusion is disposed away from the connection surface of the second capacitor and the third capacitor. The common-mode filter assembly includes multiple stages of common-mode filter modules with identical structures. The multiple stages of common-mode filter modules are mounted on the same circuit board, and the first and second coils of the previous stage common-mode filter module are respectively connected to the corresponding coils of the next stage common-mode filter module.

[0009] Preferably, the insulating base is provided with a slot that matches the circuit board. The circuit board and the slot are provided with oblique through holes or oblique threaded holes, and the extension line of the oblique through holes or oblique threaded holes intersects the plane where the first common mode inductor is located. The fixing bolt passes through the oblique through holes or oblique threaded holes and is fixedly connected to the oblique nut provided at the bottom of the insulating base. The top of the fixing bolt is provided with a deformation section with elastic deformation capability. When the fixing bolt and the oblique nut are in the tightened position, the deformation section abuts against the magnetic core of the first common mode inductor.

[0010] Preferably, both elastic conductive sheets are mounted on the circuit board, and the other end of the elastic conductive sheets extends toward the third capacitor or the second capacitor respectively. When the deformation of the elastic conductive sheets is zero, a first gap is reserved between the other end of the two elastic conductive sheets and the third capacitor or the second capacitor. When the other end of the elastic conductive sheet touches the side of the third capacitor or the second capacitor, the elastic conductive sheet is not in the maximum deformation state.

[0011] Preferably, the oblique through hole or oblique threaded hole extends towards the middle region of the two inductor coils. The fixing bolt includes a first nut and a first stud. A second capacitor is encapsulated inside the first nut, and one pole of the second capacitor extends with an elastic conductive sheet. The other pole of the second capacitor is connected to the differential mode inductor coil L3 inside the first stud. The pole of the second capacitor away from the elastic conductive sheet is also provided with a conductive tapered groove for connecting to a common mode inductor coil, for accommodating a tapered inductor connector and achieving electrical connection. The first stud includes a threaded section near the first nut and a deformed section away from the first nut. When the circuit board and the insulation protection mechanism are in the installation state, the top of the fixing bolt abuts against the side of the magnetic core, and the coil connection insert at the top of the first stud abuts against one electrode of the differential mode capacitor.

[0012] Preferably, the switching switch includes a first connection terminal for connecting to the first impedance mismatch network structure, a second connection terminal for connecting to the L mismatch network, a third connection terminal for connecting to the filter structure, and a fourth connection terminal for connecting to the C mismatch network; the switching switch is provided with a first conductive block, a second conductive block, and a third conductive block at the connection points with the second, third, and fourth connection terminals, respectively; when the switching switch is in the first state, the first connecting piece is connected to the first conductive block, and the second connecting piece is connected to the second conductive block; when the switching switch is in the second state, the first connecting piece is connected to the second conductive block, and the second connecting piece is connected to the third conductive block.

[0013] Preferably, the ends of the first connecting piece and the second connecting piece away from the fixed end are provided with elastic magnetic attraction structures. The elastic magnetic attraction structure includes a first spring and a second spring connected to the first connecting piece or the second connecting piece, and the first spring and the second spring are respectively disposed on both sides of the first connecting piece or the second connecting piece. The other ends of the first spring and the second spring are each connected to a magnetic iron sheet.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] This invention employs an insulation protection mechanism to isolate the multi-stage common-mode filter modules from each other, achieving a reduction in the size of the power filter while increasing the number of filter stages and ensuring filtering effectiveness. Furthermore, by using a switching switch to change the matching states of the L-mismatch network and C-mismatch network, the EMI power filter can reliably adapt to noise sources and loads with varying impedances, further expanding its applicability while minimizing its size.

[0016] Setting the switch to a soft contact method with an elastic magnetic attraction structure can ensure the reliability of the connection. Furthermore, elastic magnetic attraction structures are set on both sides of the first and second connecting pieces, which can facilitate the switching of L mismatch network and C mismatch network with almost zero wear.

[0017] By setting up a circuit board, the common-mode inductor and common-mode capacitor are respectively placed on both sides of the circuit board, which cleverly achieves a reliable connection between the two while ensuring the overall volume is minimized. In addition, since the common-mode capacitor has high grounding requirements, it is necessary to ensure its reliable grounding. In order to ensure the filtering effect, an elastic conductive sheet is set at the bottom of the common-mode capacitor to ensure the reliable grounding of the common-mode capacitor. Attached Figure Description

[0018] Figure 1 This is a circuit diagram of an EMI power filter with an insulation protection mechanism according to the present invention.

[0019] Figure 2 This is a schematic diagram of the internal structure of a switching switch in a first embodiment of an EMI power filter with an insulation protection mechanism according to the present invention;

[0020] Figure 3 This is a schematic diagram of the internal structure of a switching switch in a second embodiment of an EMI power filter with an insulation protection mechanism according to the present invention;

[0021] Figure 4 This is a schematic diagram of the external structure of a switching switch in an EMI power filter with an insulation protection mechanism according to the present invention.

[0022] Figure 5 This is a schematic diagram of the structure of the first common-mode inductor in an EMI power filter with an insulation protection mechanism according to the present invention.

[0023] Figure 6 For the present invention Figure 5 A schematic diagram of the cross-sectional structure along the AA direction;

[0024] Figure 7 This is a schematic diagram of the structure of the first common-mode inductor in a second embodiment of an EMI power filter with an insulation protection mechanism according to the present invention;

[0025] Figure 8 For the present invention Figure 7 Enlarged structural diagram at point B;

[0026] Figure 9 This is a schematic diagram of the fixing bolt structure of the first common-mode inductor in a second embodiment of an EMI power filter with an insulation protection mechanism according to the present invention.

[0027] In the diagram: 1. First impedance mismatch network structure; 101. First connection terminal; 102. Second connection terminal; 103. Third connection terminal; 104. Fourth connection terminal; 105. Fixed end; 106. First connecting piece; 107. Second connecting piece; 108. First conductive block; 109. Second conductive block; 110. Third conductive block; 111. Groove; 112. Indicator head; 11. Elastic magnetic attraction structure; 1101. First spring; 1102. Second spring; 1103. Magnetic iron piece; 12. Switch; 2. Common mode filter assembly; 201. First common mode inductor; 2011. Magnetic core; 2012. First coil; 2013. Second coil; 202. First common mode capacitor; 2021. Second capacitor; 2022. Third... 1. Capacitor; 2023. Elastic conductive sheet; 203. Circuit board; 2031. Inductor connector; 204. Second common-mode inductor; 205. Second common-mode capacitor; 3. Differential-mode filter; 4. Second impedance mismatch network structure; 5. Noise source; 6. Noise load; 7. Insulation protection mechanism; 701. Insulation base; 7011. Slot; 7012. Angled through hole; 7013. Angled nut; 702. Insulation protective cover; 8. Fixing bolt; 801. First nut; 802. First stud; 8020. Threaded section; 8021. Deformation section; 8022. Differential-mode inductor; 8023. Conductive conical groove; 803. Coil connection insert; 804. First leveling block; 805. Second leveling block; 9. Differential-mode capacitor; 901. Protective sleeve. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] like Figure 1As shown, the first embodiment of the power filter provided by the present invention is an EMI power filter with an insulation protection mechanism. The EMI power filter includes a filter structure and a first impedance mismatch network structure 1 and a second impedance mismatch network structure 4 respectively connected to the input and output terminals of the filter structure. The first impedance mismatch network structure 1 and the second impedance mismatch network structure 4 have the same structure. The first impedance mismatch network structure 1 includes an L mismatch network, a C mismatch network, and a switching switch 12. The switching switch 12 is used to switch the connection state of the L mismatch network and the C mismatch network with the filter structure. The switching switch 12 includes... The switch 12 includes a fixed end 105, a first connecting piece 106, and a second connecting piece 107. One end of each of the first connecting piece 106 and the second connecting piece 107 is rotatably connected to the fixed end 105. The switch 12 includes a first state and a second state. When the switch 12 is in the first state, the first connecting piece 106 and the second connecting piece 107 connect the L mismatch network to the filter structure, and the C mismatch network is disconnected from the filter structure. When the switch 12 is in the second state, the first connecting piece 106 and the second connecting piece 107 connect the C mismatch network to the filter structure, and the L mismatch network is disconnected from the filter structure.

[0030] The principle that must be followed when designing EMI filters is impedance mismatch, meaning the impedance of the filter and the source must be extremely mismatched. To achieve maximum attenuation within the stopband, the impedances of the filter's input and output terminals must be opposite to the impedance of the connected noise source 5. If the noise source 5 is determined to have a low impedance, then the impedance at the filter's input terminal connected to the noise source 5 must be as high as possible. Since EMI (electromagnetic interference) signals are generally high-frequency, according to the inductor impedance formula, Z... L =2πf L Here, f is the frequency and L is the inductance. The higher the frequency, the greater the impedance. Therefore, the noise source 5 needs to be connected to the common-mode inductor of the filter (i.e., the L mismatch network). For low-impedance signals, they should be connected to the high-impedance (inductance) end of the filter, where the signal will be directly dissipated in the inductor. Similarly, to achieve a low input impedance for the filter, Z... C =1 / 2πf CThe higher the frequency, the lower the impedance. For high-impedance signals from noise source 5, when connected to the low-impedance end (capacitor) of the filter, they will be directly released along the low-impedance path. This increases the applicability of the filter. Depending on the specific noise source 5 and noise load 6, such as connecting to the motor controller of a new energy electric vehicle, or a car air conditioning or motor drive system, the first impedance mismatch network structure 1 and the second impedance mismatch network structure 4 can be adjusted to be either an L-mismatch network or a C-mismatch network, depending on the magnitude of the actual noise source 5 and noise load 6. Thus, by setting the switching switch 12 to switch the matching state of the L-mismatch network and the C-mismatch network, the EMI power filter can reliably be applied to noise sources 5 and noise loads 6 with different high and low impedances, increasing the applicability of the filter.

[0031] like Figure 1 and Figure 2 As shown. In a first embodiment of the switching switch 12 provided by the present invention, the L-mismatch network in the first impedance mismatch network structure 1 includes a first resistor R1 and a first inductor L1 (the L-mismatch network in the second impedance mismatch network structure 2 includes a second resistor R2 and a second inductor L2). One end of the first inductor L1 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is connected to the fixed terminal 105. When the switching switch 12 is in the first state, the other end of the first inductor L1 is connected to the first connecting piece 106, and the second connecting piece 107 is connected to the filter structure. The C-mismatch network in the first impedance mismatch network structure 1 includes a first capacitor C1 (the C-mismatch network in the second impedance mismatch network structure 2 includes a second capacitor C2). One end of the first capacitor C1 is grounded. When the switching switch 12 is in the second state, the other end of the first capacitor C1 is connected to the second connecting piece 107, and the first connecting piece 106 is connected to the filter structure. This circuit connection structure minimizes additional wiring connections, ensuring minimal wiring while enabling switching between L-mismatch and C-mismatch network matching states. This switching connection method also helps reduce the overall size of the filter.

[0032] like Figure 1 and Figure 3As shown, in a second embodiment of the switching switch 12 provided by the present invention, the switching switch 12 includes a first connection terminal 101 for connecting to a first impedance mismatch network structure 1, a second connection terminal 102 for connecting to an L mismatch network, a third connection terminal 103 for connecting to a filter structure, and a fourth connection terminal 104 for connecting to a C mismatch network; a first conductive electromagnetic block 108, a second conductive electromagnetic block 109, and a third conductive electromagnetic block 110 are respectively provided at the connection points of the switching switch 12 with the second connection terminal 102, the third connection terminal 103, and the fourth connection terminal 104; when the switching switch 12 is in the first state, the first connecting piece 106 is connected to the first conductive electromagnetic block 108, and the second connecting piece 107 is connected to the first conductive electromagnetic block 108. Two conductive electromagnetic blocks 109 are connected. When the switch 12 is in the second state, the first connecting piece 106 is connected to the second conductive electromagnetic block 109, and the second connecting piece 107 is connected to the third conductive electromagnetic block 110. Both the first connecting piece 106 and the second connecting piece 107 have an elastic magnetic attraction structure 11 at one end away from the fixed end 105. The elastic magnetic attraction structure 11 includes a first spring 1101 and a second spring 1102 connected to either the first connecting piece 106 or the second connecting piece 107. The first spring 1101 and the second spring 1102 are respectively located on both sides of the first connecting piece 106 or the second connecting piece 107. The other ends of both the first spring 1101 and the second spring 1102 are connected to a magnetic attraction piece 1103. Setting the switch 12 to a soft contact method with the elastic magnetic attraction structure 11 ensures reliable connection. Furthermore, by providing the elastic magnetic attraction structure 11 on both sides of the first connecting piece 106 and the second connecting piece 107, the L-mismatch network and the C-mismatch network can be easily switched with almost zero wear.

[0033] Furthermore, the outer or inner side of the housing of the switch 12 can be covered with a shielding layer to prevent the magnetic attraction structure from generating additional electromagnetic interference.

[0034] like Figure 4 The diagram shows the external structure of the switch 12. The switch 12's housing has a rectangular groove 111 or a rectangular lever that is fixedly connected to the rotating connection of the fixed end 105. This groove allows for the insertion of a flathead screwdriver or other tool, or for turning with pliers or other instruments, to rotate the rotating connection, thereby enabling manual switching between the L-mismatch network and the C-mismatch network. An indicator head 112 is located on the side of the rotating connection outside the switch 12 to indicate whether the currently connected network is the L-mismatch network or the C-mismatch network.

[0035] like Figure 1 , Figure 5 and Figure 6The diagram shows the structure of the first common-mode inductor 201. The common-mode filter assembly 2 includes two stages of common-mode filter modules with identical structures (first common-mode inductor 201, first common-mode capacitor 202, second common-mode inductor 204, and second common-mode capacitor 205). The two stages of common-mode filter modules are mounted on the same circuit board 203. The first coil 2012 and the second coil 2013 of the previous stage common-mode filter module are respectively connected to the corresponding coils of the next stage common-mode filter module.

[0036] The filter structure further includes a differential-mode filter 3. The input terminal of the common-mode filter component 2 is connected to the output terminal of the first impedance mismatch network structure 1, the output terminal of the common-mode filter component 2 is connected to the input terminal of the differential-mode filter 3, and the output terminal of the differential-mode filter 3 is connected to the input terminal of the second impedance mismatch network structure 4. In this embodiment, the differential-mode filter 3 includes inductors L3 and L4 connected to the two ends of the second common-mode capacitor 205, and capacitor C3 connected to the two ends of inductors L3 and L4. The circuit board 203 includes an insulating surface and a conductive surface. The first common-mode inductor 201 is mounted on the insulating surface of the circuit board 203. The first common-mode inductor 201 includes a rectangular magnetic core 2011 and a first common-mode inductor C3 that is parallel to each other on the magnetic core 2011. The insulating base 701 has a slot 7011 that matches the circuit board 203, and the circuit board 203 and the slot 701 have a through hole 7012 or a threaded hole. The extension line of the through hole 7012 or the threaded hole intersects the plane where the first common mode inductor 201 is located. The fixing bolt 8 passes through the through hole 7012 or the threaded hole and is fixedly connected to the nut 7013 at the bottom of the insulating base 701. The top of the fixing bolt 8 has a deformation section 801 with elastic deformation capability. When the fixing bolt 8 and the nut 7013 are in the tightened position, the deformation section 8021 abuts against the magnetic core 2011 of the first common mode inductor 201. Therefore, by setting the circuit board 203, the common-mode inductor and common-mode capacitor are respectively located on both sides of the circuit board 203, which cleverly achieves a reliable connection between the two while ensuring a minimal overall volume. At the same time, since the vehicle power filter requires a small size and vibration resistance, the four corners of the first common-mode inductor 201 are provided with oblique through holes 7012 or oblique threaded holes and matching bolts. Since the deformation section 8021 has a certain elastic deformation capability, this oblique locking method can firmly clamp the magnetic core 2011, avoiding the impact of vehicle body shaking and causing collisions between the inductor coils of adjacent common-mode filter modules. In addition, the inductor coil is covered with an insulating protective cover 702, which can also prevent contact and collision between adjacent coils. While ensuring a small structural volume, the safety performance of the filter is further improved.

[0037] like Figure 5 As shown, the first common-mode capacitor 202 is mounted on one side of the conductive surface of the circuit board 203. The first common-mode capacitor 202 includes a second capacitor 2021 and a third capacitor 2022 connected in series. The other ends of the second capacitor 2021 and the third capacitor 2022 are connected to an elastic conductive sheet 2023. One end of the first coil 2012 and the second coil 2013 passes through the circuit board 203 and is connected to the other ends of the second capacitor 2021 and the third capacitor 2022, respectively. Two elastic conductive sheets 2023 are provided. One end of the two elastic conductive sheets 2023 is fixedly mounted on one end of the second capacitor 2021 and the third capacitor 2022, respectively, and the other end extends towards the third capacitor 2022 or the second capacitor 2021, respectively. When the deformation of the elastic conductive sheet 2023 is zero, a first gap is reserved between the other end of the two elastic conductive sheets 2023 and the third capacitor 2022 or the second capacitor 2021. The elastic conductive sheet 2023 is configured with an arc-shaped structure, with its arc-shaped protrusion facing away from the connection surface of the second capacitor 2021 and the third capacitor 2022. When the other end of the elastic conductive sheet 2023 contacts the side of the third capacitor 2022 or the second capacitor 2021, the elastic conductive sheet 2023 is not in its maximum deformation state. Because the common-mode capacitor has high grounding requirements, reliable grounding must be ensured. To guarantee the filtering effect, an elastic conductive sheet 2023 is placed at the bottom of the common-mode capacitor to ensure reliable grounding. When the filter is encapsulated as a whole, the elastic conductive sheet 2023 directly contacts the metal casing, ensuring reliable grounding.

[0038] like Figure 7 As shown, the present invention provides a second embodiment of the first common-mode inductor 201. In this embodiment, the circuit board 203 and the slot 7011 still have oblique through holes 7012 or oblique threaded holes. The extension lines of the oblique through holes 7012 or oblique threaded holes intersect the plane where the first common-mode inductor 201 is located, and the oblique through holes 7012 or oblique threaded holes extend towards the middle region of the two inductor coils. The fixing bolt 8 in this embodiment includes a first nut 801 and a first stud 802. The first nut 801 encapsulates a second capacitor 2021, and one pole of the second capacitor 2021 extends with an elastic conductive sheet 2023. The other pole of the second capacitor 2021 is connected to the differential-mode inductor 8022 coil L3 in the first stud 802. The first stud 802 and the differential-mode inductor 8022 are encapsulated with insulating shielding material. Furthermore, as Figure 8As shown, the second capacitor 2021, on one pole away from the elastic conductive sheet 2023, is also provided with a conductive conical groove 8023 for connection with a common-mode inductor coil. The conductive conical groove 8023 is made of metal and is electrically connected to the pole of the second capacitor 2021 away from the elastic conductive sheet 2023. The cross-sectional area of ​​the conductive conical groove 8023 gradually decreases along the direction close to the second capacitor 2021. The conductive conical groove 8023 is used to accommodate a conical inductor connector 2031. By setting the inductor connector 2031 in a conical shape and providing the conductive conical groove 8023 on one side of the second capacitor 2021, an effective electrical connection between the common-mode inductor coil and the common-mode capacitor can be achieved while the circuit board 203 is being installed. The first nut 801 is smoothly connected to the insulating base 701 via a first leveling block 804 and smoothly connected to the horizontal plane via a second leveling block 805. The elastic conductive sheet 2023 is disposed through the second leveling block 805.

[0039] like Figures 7-9 As shown, in this embodiment, the differential mode capacitor 9 (i.e. Figure 1 The differential-mode capacitor C3 is fixedly mounted on the circuit board 203 on one side of the common-mode inductor core 2011 (because the inductor coil has a certain diameter, the circuit board 203 on the side of the core 2011 has a certain blank space). The electrodes of the differential-mode capacitor 9 are located on its left and right sides, corresponding to the common-mode inductor coil. The first stud 802 includes a threaded section 8020 near the first nut 801 and a deformable section 8021 away from the first nut 801. The threaded section 8020 is threaded, and the deformable section 8021 is not threaded. The deformable section 8021 has a certain elastic deformation capability, so that when the circuit board 203 and the insulation protection mechanism 7 are in the installation state, the top of the fixing bolt 8 can stably abut against the side of the core 2011, realizing the reliable stability of the installation structure. The differential-mode inductor 8022 coil L3 inside the first stud 802 passes through the top of the first stud 802, exposing the coil connection insert 803. The coil connection insert 803 and the differential-mode inductor 8022 coil L3 are an integral structure, and the coil connection insert 803 is inclined, with the inclination direction consistent with the direction of the inclined through hole 7012 or the inclined threaded hole. The electrodes of the differential-mode capacitor 9 are located on its left and right sides, and the electrodes of the differential-mode capacitor 9 are provided with protective sleeves 901 sleeved on the outside of the electrodes, with a slack at the front end of the protective sleeve 901. The protective sleeve 901 is inclined downward to match the coil connection insert 803. When the circuit board 203 and the insulation protection mechanism 7 are in the installed state, the coil connection insert 803 is inserted into the protective sleeve 901, realizing the connection between the differential-mode capacitor 9 and the differential-mode inductor 8022 coil L3. This connection method realizes the common-mode filter module and the differential-mode filter module in common connection, which is reliable and convenient, and reduces the overall size of the filter structure.

[0040] Working Principle: This invention features an insulation protection mechanism 7 that isolates the multi-stage common-mode filter modules from each other, achieving a reduction in the size of the power filter while increasing the number of filter stages and ensuring filtering effect. Furthermore, by using a switching switch 12 to switch the matching states of the L-mismatch network and C-mismatch network, the EMI power filter can reliably adapt to noise sources 5 and noise loads 6 with different high and low impedances, thus increasing the filter's applicability while minimizing its size. The switching switch 12 is configured with a soft contact method using an elastic magnetic structure 11, ensuring reliable connection. Elastic magnetic structures 11 are also provided on both sides of the first connecting piece 106 and the second connecting piece 107, allowing for convenient switching between the L-mismatch network and the C-mismatch network with almost zero wear. By setting the circuit board 203, the common mode inductor and common mode capacitor are respectively set on both sides of the circuit board 203, which cleverly achieves a reliable connection between the two while ensuring the minimum overall volume. In addition, since the common mode capacitor has high grounding requirements, it is necessary to ensure its reliable grounding. In order to ensure the filtering effect, an elastic conductive sheet 2023 is set at the bottom of the common mode capacitor to ensure the reliable grounding of the common mode capacitor.

[0041] The housing of the switch 12 has a rectangular groove 111 that is fixedly connected to the rotating connection of the fixed end 105. This groove allows a flathead screwdriver or a slotted pin to be inserted and rotated, thereby enabling manual switching between the L mismatch network and the C mismatch network. An indicator head 112 is located on the outer side of the rotating connection of the switch 12 to indicate whether the currently connected network is the L mismatch network or the C mismatch network.

[0042] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An EMI power filter with insulation protection mechanism, characterized by, The EMI power filter comprises a filter structure and a first impedance mismatch network structure (1) and a second impedance mismatch network structure (4) connected to the input end and the output end of the filter structure respectively, the first impedance mismatch network structure (1) and the second impedance mismatch network structure (4) are the same in structure, the first impedance mismatch network structure (1) comprises an L mismatch network, a C mismatch network and a switching switch (12), the switching switch (12) is used for switching the connection state of the L mismatch network and the C mismatch network with the filter structure; the filter structure comprises a common mode filter assembly (2), the common mode filter assembly (2) comprises a multi-stage common mode filter module, the common mode filter module comprises a first common mode inductor (201), a first common mode capacitor (202) and a circuit substrate (203), the circuit substrate (203) is provided with an insulation protection mechanism (7), the insulation protection mechanism (7) comprises an insulation base (701) and an insulation protective shell (702) connected to the top of the insulation base (701), the insulation base (701) is used for fixedly connecting the circuit substrate (203) and the first common mode inductor (201), the insulation protective shell (702) is sleeved outside the inductor coil and is used for isolating the multi-stage common mode filter module; The filter structure further comprises a differential mode filter (3), the input end of the common mode filter assembly (2) is connected with the output end of the first impedance mismatch network structure (1), the output end of the common mode filter assembly (2) is connected with the input end of the differential mode filter (3), and the output end of the differential mode filter (3) is connected with the input end of the second impedance mismatch network structure (4); the circuit substrate (203) comprises an insulating surface and a conductive surface, the first common mode inductor (201) is installed on the insulating surface of the circuit substrate (203), the first common mode inductor (201) comprises a rectangular magnetic core and a first coil (2012) and a second coil (2013) which are sleeved on the magnetic core (2011) in parallel, the first common mode capacitor (202) is installed on one side of the conductive surface of the circuit substrate (203), the first common mode capacitor (202) comprises a second capacitor (2021) and a third capacitor (2022) connected in series, the other end of the second capacitor (2021) and the third capacitor (2022) is connected with an elastic conductive sheet (2023), one end of the first coil (2012) and the second coil (2013) penetrates through the circuit substrate (203) and is connected with the other end of the second capacitor (2021) and the third capacitor (2022) respectively; The insulating base (701) is provided with a clamping groove (7011) matched with the circuit substrate (203), the circuit substrate (203) and the clamping groove (7011) are provided with a slanting through hole (7012) or a slanting threaded hole, the extension line of the slanting through hole (7012) or the slanting threaded hole intersects with the plane where the first common mode inductor (201) is located, the fixing bolt (8) is fixedly connected with the slanting nut (7013) arranged at the bottom of the insulating base (701) through the slanting through hole (7012) or the slanting threaded hole, and the top of the fixing bolt (8) is provided with a deformation section (8021) with elastic deformation capacity; when the fixing bolt (8) and the slanting nut (7013) are in a fastening in-place state, the deformation section (8021) abuts against the magnetic core (2011) of the first common mode inductor (201).

2. The EMI power filter with insulation protection mechanism according to claim 1, wherein, The switch (12) comprises a fixed end (105), a first connecting piece (106) and a second connecting piece (107), one end of the first connecting piece (106) and the second connecting piece (107) is rotatably connected with the fixed end (105), the switch (12) comprises a first state and a second state, when the switch (12) is in the first state, the first connecting piece (106) and the second connecting piece (107) connect the L mismatch network with the filter structure, the C mismatch network and the filter structure are in a cut-off state, when the switch (12) is in the second state, the first connecting piece (106) and the second connecting piece (107) connect the C mismatch network with the filter structure, and the L mismatch network and the filter structure are in a cut-off state.

3. The EMI power filter with insulation protection mechanism according to claim 2, wherein, The L mismatch network comprises a first resistor R1 and a first inductor L1, one end of the first inductor L1 is connected with one end of the first resistor R1, the other end of the first resistor R1 is connected with the fixed end (105), when the switch (12) is in the first state, the other end of the first inductor L1 is connected with the first connecting piece (106), and the second connecting piece (107) is connected with the filter structure; the C mismatch network comprises a first capacitor C1, one end of the first capacitor C1 is grounded, when the switch (12) is in the second state, the other end of the first capacitor C1 is connected with the second connecting piece (107), and the first connecting piece (106) is connected with the filter structure.

4. The EMI power filter with insulation protection mechanism according to claim 1, wherein, The elastic conductive sheet (2023) is provided with two, one end of the two elastic conductive sheets (2023) is fixedly installed on one end of the second capacitor (2021) and the third capacitor (2022) respectively, the elastic conductive sheet (2023) is provided in an arc-shaped structure, and the arc-shaped protruding portion thereof is away from the connecting surface of the second capacitor (2021) and the third capacitor (2022); the common mode filter assembly (2) comprises common mode filter modules of a same multi-stage structure, the common mode filter modules are installed on the same circuit substrate (203), and the first coil (2012) and the second coil (2013) of a front-stage common mode filter module are connected with corresponding coils of a next-stage common mode filter module respectively.

5. The EMI power filter with insulation protection mechanism according to claim 1, wherein, Two elastic conductive sheets (2023) are mounted on the circuit substrate (203), and the other ends of the elastic conductive sheets (2023) extend towards the third capacitor (2022) or the second capacitor (2021) respectively, and when the deformation amount of the elastic conductive sheet (2023) is zero, a first interval is reserved between the other ends of the two elastic conductive sheets (2023) and the third capacitor (2022) or the second capacitor (2021), and when the elastic conductive sheet (2023) is in contact with the side edge of the third capacitor (2022) or the second capacitor (2021), the elastic conductive sheet (2023) is not in the maximum deformation state.

6. The EMI power filter with insulation protection mechanism according to claim 1, wherein, The oblique through hole or oblique threaded hole extends to the middle region of the two inductors, the fixing bolt includes a first nut and a first stud, the first nut encapsulates a second capacitor, one pole of the second capacitor extends an elastic conductive sheet, and the other pole of the second capacitor is connected with a differential mode inductor L3 in the first stud; the pole of the second capacitor away from the elastic conductive sheet is further provided with a conductive taper groove for connecting with a common mode inductor, for accommodating a tapered inductor connecting head and realizing electrical connection; the first stud includes a threaded section close to one side of the first nut and a deformation section away from the first nut, when the circuit substrate and the insulation protection mechanism are in the installed state, the top of the fixing bolt is in contact with the side edge of the magnetic core, and the coil connecting sheet at the top of the first stud is in contact with one side electrode of the differential mode capacitor.

7. The EMI power filter with insulation protection mechanism according to claim 6, wherein, The switching switch (12) includes a first connection end (101) for connecting with the first impedance mismatch network structure (1), a second connection end (102) for connecting with the L mismatch network, a third connection end (103) for connecting with the filter structure, and a fourth connection end (104) for connecting with the C mismatch network; the first conductive magnetic block (108), the second conductive magnetic block (109) and the third conductive magnetic block (110) are respectively arranged at the connection positions of the second connection end (102), the third connection end (103) and the fourth connection end (104) in the switching switch (12); when the switching switch (12) is in the first state, the first connecting sheet (106) is connected with the first conductive magnetic block (108), and the second connecting sheet (107) is connected with the second conductive magnetic block (109); when the switching switch (12) is in the second state, the first connecting sheet (106) is connected with the second conductive magnetic block (109), and the second connecting sheet (107) is connected with the third conductive magnetic block (110).

8. The EMI power filter with insulation protection mechanism according to claim 7, wherein, The first connecting piece (106) and the second connecting piece (107) are provided with elastic magnetic attraction structures (11) at one end away from the fixed end (105), the elastic magnetic attraction structures (11) comprise first springs (1101) and second springs (1102) connected with the first connecting piece (106) or the second connecting piece (107), and the first springs (1101) and the second springs (1102) are arranged on the two sides of the first connecting piece (106) or the second connecting piece (107) respectively, and the other end of the first spring (1101) and the second spring (1102) is connected with a magnetic attraction iron sheet (1103).

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