Choke system for reducing common mode current in AC drive system

Abstract

The present disclosure relates to a choke system for reducing common mode current in an AC drive system. The present disclosure addresses common mode current and bearing current in an alternating current (AC) drive system by using an AC choke assembly integrated with a shielded coaxial electrical cable. This design weakens common mode current and ensures electromagnetic compatibility. The AC choke assembly includes a magnetic core with an axial bore that receives a coaxial electrical cable. The cable is surrounded by a metal housing and insulated by a dielectric separator. An optional dielectric outer cover may further insulate the metal housing. Thermal interface pastes may be used to maximize heat transfer between layers of an AC choke. One side of the metal housing is connected to the first set of coaxial cable shield ends, or the other side may be connected to a traction drive unit (TDU) or a traction power inverter module (TPIM). Alternatively, the AC choke may be located in a middle section of the coaxial cable.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an alternating current (AC) choke for use with all-electric or hybrid electric motor vehicles and other electrical applications requiring the use of shielded cables to reduce common mode current and bearing current in AC drive systems. BACKGROUND

[0002] All-electric and / or hybrid electric vehicles can use an AC traction drive unit (TDU) to propel the vehicle. A direct current / alternating current (DC / AC) traction power inverter module (TPIM) can be used to provide alternating current to the TDU. The AC power system of an electric vehicle can emit high frequency (up to about 10 MHz) electromagnetic noise (e.g., from the inverter module), which can interfere with radios, sensors, navigation, and computer operations inside the vehicle. An AC choke made of a ferrous-based material can be used to reduce or attenuate high frequency common mode current and bearing current in current carrying conductors or busses. Core overheating of the AC choke can reduce the permeability of the core and reduce the shielding performance of the choke. SUMMARY

[0003] The present disclosure addresses common mode current and bearing current in alternating current (AC) drive systems by using an AC choke assembly integrated with a shielded coaxial electrical cable. This design attenuates common mode current and ensures electromagnetic compatibility. The AC choke assembly includes a magnetic core defining an axial bore that houses the coaxial electrical cable. The cable is surrounded by a metal shell and insulated by a dielectric spacer. An optional dielectric outer cap can further insulate the metal shell. Thermal interface paste can be used to maximize heat transfer between the layers of the AC choke. One side of the metal shell is connected to a first set of coaxial cable shield end portions, or the other side can be connected to a traction drive unit (TDU) or traction power inverter module (TPIM). Alternatively, the AC choke can be located in an intermediate section of the coaxial cable.

[0004] The methods and apparatus disclosed herein address the problem of reducing common mode current and bearing current in electric traction drive systems of vehicles. The present disclosure teaches an AC choke assembly that effectively reduces and attenuates common mode current in AC drive systems. This helps reduce electrical noise and interference, resulting in improved system performance and reliability. By using a metal housing for the AC choke assembly, this effectively attenuates electromagnetic interference (EMI). This helps comply with EMC regulations and standards, ensuring that the system operates without interfering with other electronic devices in the vehicle. The use of thermal interface material in the AC choke assembly helps maximize the rate of heat transfer across adjacent layers. This improves the heat dissipation capability of the AC choke, preventing overheating and ensuring optimal performance and longevity of the system. The proposed design enables the AC choke assembly to be easily integrated into the coaxial electrical cable system of the AC drive system. Options are disclosed for connecting the metal housing to the end of the coaxial cable shield or for connecting the magnetic core to the end of the coaxial shield (i.e., shield end), providing flexibility in system design and installation. The AC choke can be located over the unshielded portion of the coaxial electrical cable, which reduces the average magnetic length of the AC choke design and results in higher magnetic inductance (and thus, better electromagnetic shielding) of the system. The conventional AC current frequency can be in the range of 1 to 10 MHz.

[0005] In a first embodiment, an AC choke for reducing common mode current and bearing current in an AC drive system includes a magnetic core defining an axial bore inside the magnetic core, a dielectric separator surrounding the magnetic core, and a metal housing surrounding the dielectric separator. The dielectric separator electrically isolates the magnetic core from the metal housing. The AC choke can further have a first gap disposed between the magnetic core and the dielectric separator, a second gap disposed between the dielectric separator and the metal housing, a first layer of thermal interface material filling the first gap, and a second layer of thermal interface material filling the second gap. An optional dielectric outer jacket can surround the metal housing. An optional third layer of thermal interface material can be placed between the metal housing and the optional dielectric outer jacket. The magnetic core can be a ferrite material or a nanocrystalline ferrous material. The dielectric separator and the optional dielectric outer jacket can be a semi-crystalline thermoplastic high temperature polymer material (e.g., polyphenylene sulfide (PPS)). The metal housing can be an aluminum alloy and / or a steel alloy.

[0006] In some embodiments, the shape of the magnetic core can be rectangular, rounded rectangular, circular, triangular, or rounded triangular.

[0007] In some embodiments, the magnetic core can be made of a plurality of nanocrystalline ferrous ribbons wound in a rounded rectangular geometry, with the axial bore disposed inside the magnetic core.

[0008] In some embodiments, the AC choke has at least one coaxial electrical cable positioned inside and passing through a bore located inside a magnetic core. Each coaxial electrical cable includes an axial center conductor, a coaxial dielectric insulator surrounding the axial center conductor, a conductive coaxial shield surrounding the coaxial dielectric insulator, and a dielectric coaxial jacket surrounding the conductive coaxial shield.

[0009] In some embodiments, the AC choke is positioned along a middle section of the coaxial electrical cable.

[0010] In some embodiments, the AC choke is positioned at an end of the coaxial electrical cable.

[0011] In some embodiments, the conductive coaxial shield is electrically connected to an outer surface of a metal housing of the AC choke. In other embodiments, the conductive coaxial shield is electrically connected to an inner surface of a metal housing of the AC choke.

[0012] In some embodiments, a portion of the dielectric coaxial jacket and the conductive coaxial shield is stripped away from the at least one coaxial electrical cable, thereby defining an exposed portion of the conductive coaxial shield, and thereby defining an unshielded axial portion of the at least one coaxial electrical cable. The conductive coaxial shield can be discontinuous along the unshielded axial portion. The AC choke can be positioned over the unshielded axial portion of the coaxial electrical cable.

[0013] In some embodiments, a metal housing of the AC choke is electrically connected to a metal housing of a TDU, and the conductive coaxial shield is connected to the metal housing.

[0014] In some embodiments, a metal housing of the AC choke is electrically connected to a metal housing of a TPIM, and the conductive coaxial shield is connected to the metal housing.

[0015] In some embodiments, the conductive coaxial shield is connected to the magnetic core, and there is no metal housing and no dielectric separator.

[0016] In some embodiments, three parallel coaxial electrical cables are positioned inside and passing through a bore located inside a magnetic core of the AC choke.

[0017] In some embodiments, an AC choke assembly includes a TDU connected to a metal housing of the AC choke.

[0018] In some embodiments, a system for reducing common mode current and bearing current in an AC drive system includes an AC drive system, where an AC traction motor and associated power electronics are connected by one or more coaxial electrical cables; and an AC choke assembly integrated with the one or more coaxial electrical cables for reducing common mode current and ensuring EMC.

[0019] In some embodiments, an AC drive system includes an AC choke, where one or more coaxial electrical cables pass through the AC choke, the coaxial electrical cables connected to a TDU configured for use in an electric vehicle.

[0020] In some embodiments, an AC drive system includes an AC choke, where one or more coaxial electrical cables pass through the AC choke, the coaxial electrical cables connected to a TPIM configured for use in an electric vehicle.

[0021] In some embodiments, an exposed surface of the AC choke is covered by a dielectric insulating material.

[0022] In some embodiments, a metal housing is removed and a conductive coaxial shield is connected to a magnetic core of the AC choke.

[0023] In some embodiments, a vehicle includes a vehicle body, one or more road wheels connected to the vehicle body, and an AC choke assembly connected to the vehicle body. The AC choke assembly includes an AC choke, at least one coaxial electrical cable disposed inside and passing through the AC choke, and a traction drive unit (TDU) or a traction power inverter module (TPIM) connected to the AC choke. The AC choke has a magnetic core, an axial bore defined by the magnetic core, a dielectric partition surrounding the magnetic core, and a metal housing surrounding the dielectric partition. The dielectric partition electrically isolates the magnetic core from the metal housing. The at least one coaxial electrical cable has an axial center conductor, a coaxial dielectric insulator surrounding the axial center conductor, a conductive coaxial shield surrounding the coaxial dielectric insulator, and a dielectric coaxial jacket surrounding the conductive coaxial shield. The axial center conductor is connected to the TDU or TPIM, and the conductive coaxial shield is connected to the metal housing.

[0024] The present invention also includes the following technical solutions:

[0025] 1. An alternating current (AC) choke for reducing common mode current and bearing current in an AC drive system, comprising:

[0026] a magnetic core;

[0027] an axial bore defined by the magnetic core;

[0028] a dielectric spacer surrounding the magnetic core; and

[0029] a metal housing surrounding the dielectric spacer; and

[0030] wherein the dielectric spacer electrically isolates the magnetic core from the metal housing.

[0031] 2. The AC choke of aspect 1, further comprising:

[0032] a first thermal interface material layer disposed between the magnetic core and the dielectric spacer; and

[0033] a second thermal interface material layer disposed between the dielectric spacer and the metal housing.

[0034] 3. The AC choke of aspect 2, further comprising:

[0035] a dielectric outer jacket surrounding the metal housing; and

[0036] a third thermal interface material layer disposed between the metal housing and the dielectric outer jacket.

[0037] 4. The AC choke of aspect 1, wherein an exposed surface of the AC choke is covered by a dielectric insulating material.

[0038] 5. The AC choke of aspect 1,

[0039] wherein the magnetic core comprises a ferrous material selected from the group consisting of nanocrystalline ferrous material, ferrite material, and / or combinations thereof;

[0040] wherein the dielectric spacer comprises polyphenylene sulfide; and

[0041] wherein the metal housing comprises an aluminum alloy and / or a steel alloy and / or combinations thereof.

[0042] 6. The AC choke of aspect 3, wherein the dielectric outer jacket comprises polyphenylene sulfide.

[0043] 7. The AC choke of aspect 1, wherein the magnetic core is shaped as a rectangle, a rounded rectangle, a circle, a triangle, or a rounded triangle.

[0044] 8. The AC choke of aspect 1, further comprising at least one coaxial electrical cable disposed inside and passing through a bore of the magnetic core.

[0045] 9. The AC choke of claim 1, wherein the magnetic core comprises a plurality of nanocrystalline iron-containing ribbons wound in a rounded rectangular geometry, wherein the axial bore is disposed inside the magnetic core.

[0046] 10. An alternating current (AC) choke assembly for reducing common mode current and bearing current in an AC drive system, comprising:

[0047] (a) an AC choke comprising:

[0048] a magnetic core;

[0049] an axial bore defined by the magnetic core;

[0050] a dielectric spacer surrounding the magnetic core; and

[0051] a metal housing surrounding the dielectric spacer;

[0052] wherein the AC choke assembly further comprises:

[0053] (b) at least one coaxial electrical cable disposed inside the axial bore of the magnetic core and passing through the axial bore;

[0054] wherein the dielectric spacer electrically isolates the magnetic core from the metal housing; and

[0055] wherein the at least one coaxial electrical cable comprises:

[0056] (1) an axial center conductor;

[0057] (2) a coaxial dielectric insulator surrounding the axial center conductor;

[0058] (3) a conductive coaxial shield surrounding the coaxial dielectric insulator; and

[0059] (4) a dielectric coaxial jacket surrounding the conductive coaxial shield.

[0060] 11. The AC choke assembly of claim 10,

[0061] wherein a portion of the dielectric coaxial jacket and the conductive coaxial shield is stripped from the at least one coaxial electrical cable;

[0062] thereby defining an exposed portion of the conductive coaxial shield; and

[0063] thereby defining an unshielded axial portion of the at least one coaxial electrical cable.

[0064] 12. The AC choke assembly of Solution 11, wherein the AC choke is located at a mid-section of the at least one coaxial electrical cable.

[0065] 13. The AC choke assembly of Solution 11, wherein the AC choke is located at an end of the at least one coaxial electrical cable.

[0066] 14. The AC choke assembly of Solution 11, wherein the AC choke is located over an unshielded axial portion of the at least one coaxial electrical cable.

[0067] 15. The AC choke assembly of Solution 11, wherein an exposed portion of the electrically conductive coaxial shield is electrically connected to an outer surface of a metal housing of the AC choke.

[0068] 16. The AC choke assembly of Solution 11, wherein an exposed portion of the electrically conductive coaxial shield is electrically connected to an inner surface of a magnetic core of the AC choke.

[0069] 17. The AC choke assembly of Solution 11, wherein a metal housing of the AC choke is connected to a first metal housing of a traction drive unit (TDU) or a traction power inverter module (TPIM).

[0070] 18. The AC choke assembly of Solution 11, further comprising three parallel coaxial electrical cables disposed inside and passing through an axial bore of the magnetic core.

[0071] 19. The AC choke assembly of Solution 11,

[0072] wherein the metal housing is removed; and

[0073] wherein the electrically conductive coaxial shield is electrically connected to a magnetic core of the AC choke.

[0074] 20. A vehicle comprising:

[0075] a vehicle body;

[0076] one or more road wheels connected to the vehicle body; and

[0077] an alternating current (AC) choke assembly connected to the vehicle body;

[0078] wherein the AC choke assembly comprises:

[0079] (a) an AC choke comprising:

[0080] a magnetic core;

[0081] an axial bore defined by the magnetic core;

[0082] a dielectric separator surrounding the magnetic core; and

[0083] a metal housing surrounding the dielectric separator;

[0084] (b) at least one coaxial electrical cable disposed inside and passing through the axial bore of the magnetic core; and

[0085] (c) a traction drive unit (TDU) or traction power inverter module (TPIM) connected to the AC choke;

[0086] wherein the dielectric separator electrically isolates the magnetic core from the metal housing;

[0087] wherein the at least one coaxial electrical cable comprises:

[0088] (1) an axial center conductor;

[0089] (2) a coaxial dielectric insulator surrounding the axial center conductor;

[0090] (3) a conductive coaxial shield surrounding the coaxial dielectric insulator; and

[0091] (4) a dielectric coaxial jacket surrounding the conductive coaxial shield;

[0092] wherein the axial center conductor is connected to the TDU or TPIM; and

[0093] wherein the conductive coaxial shield is connected to the metal housing. BRIEF DESCRIPTION OF DRAWINGS

[0094] Figure 1A shows a cutaway perspective view of an example of a coaxial electrical cable.

[0095] Figure 1B shows a cutaway perspective view of an example of a coaxial electrical cable with a portion of a center axial conductor exposed at one end.

[0096] Figure 2A shows a schematic perspective cross-sectional view of an example of a rectangular AC choke according to the present disclosure.

[0097] Figure 2B shows a schematic perspective cross-sectional view of an example of a rectangular AC choke assembly according to the present disclosure with three parallel coaxial electrical cables disposed inside.

[0098] Figure 3AA schematic perspective view showing an example of a monolithic rectangular magnetic core with rounded corners according to this disclosure.

[0099] Figure 3B A schematic perspective view of an example of a monolithic rectangular magnetic core assembly with rounded corners according to the present disclosure is shown, wherein three parallel coaxial electrical cables are disposed inside.

[0100] Figure 4A A schematic perspective cross-sectional view showing an example of a rectangular AC choke with rounded corners according to this disclosure.

[0101] Figure 4B A schematic perspective cross-sectional view of an example of a rectangular AC choke coil assembly with rounded corners according to the present disclosure is shown, wherein three parallel coaxial electrical cables are disposed inside.

[0102] Figure 5A A schematic perspective cross-sectional view showing an example of a circular AC choke according to this disclosure.

[0103] Figure 5B A schematic perspective cross-sectional view of an example of a circular AC choke coil assembly according to this disclosure is shown, in which three parallel coaxial electrical cables are disposed inside.

[0104] Figure 6A A schematic perspective cross-sectional view showing an example of a triangular AC choke according to this disclosure.

[0105] Figure 6B A schematic perspective cross-sectional view of an example of a triangular AC choke coil assembly according to this disclosure is shown, in which three parallel coaxial electrical cables are disposed inside.

[0106] Figure 7 A schematic top view of an example of an AC choke assembly according to the present disclosure is shown, the AC choke assembly including an AC choke with three parallel coaxial electrical cables disposed inside the AC choke and passing through the AC choke in the Z-axis direction.

[0107] Figure 8A This illustrates a coaxial electrical cable electrically and mechanically integrated with an AC choke coil according to the present disclosure. Figure 7 The example shown is a schematic side cross-sectional view (section AA).

[0108] Figure 8B This illustrates a coaxial electrical cable electrically and mechanically integrated with an AC choke coil according to the present disclosure. Figure 7 The example shown is a schematic side cross-sectional view (section AA).

[0109] Figure 9AA schematic top plan view showing an example of an AC choke attached to a traction drive unit (TDU) or traction power inverter module (TPIM) according to the present disclosure, wherein three parallel coaxial electrical cables are disposed inside the AC choke and pass through the AC choke in the Z-axis direction.

[0110] Figure 9B A schematic top plan view showing an example of an AC choke attached to a traction drive unit (TDU) or traction power inverter module (TPIM) according to the present disclosure, wherein three parallel coaxial electrical cables are disposed inside the AC choke and pass through the AC choke in the Z-axis direction.

[0111] Figure 10 A schematic side cross-sectional view (section B-B) showing an example of a coaxial electrical cable electrically and mechanically integrated with an AC choke attached to a TPIM or TDU power unit according to the present disclosure. Figure 9A

[0112] Figure 11A A schematic top plan view showing an example of an AC choke housed in a sheet metal housing according to the present disclosure.

[0113] Figure 11B A schematic bottom plan view showing an example of an AC choke housed in a sheet metal housing according to the present disclosure.

[0114] Figure 11C A schematic front elevational view showing an example of an AC choke housed in a sheet metal housing according to the present disclosure.

[0115] Figure 11D A schematic side elevational view showing an example of an AC choke housed in a sheet metal housing according to the present disclosure.

[0116] Figure 12 A schematic front elevational cross-sectional view showing an example of a magnetic core of an AC choke according to the present disclosure.

[0117] Figure 13 A schematic perspective view showing an example of a triangular magnetic core of an AC choke according to the present disclosure.

[0118] Figure 14 A schematic perspective view showing an example of a vehicle having an AC choke assembly according to the present disclosure. DETAILED DESCRIPTION

[0119] ​The AC choke assemblies disclosed herein can be used in a variety of different mobile electric or hybrid electric applications (including but not limited to: automobiles, trucks, motorcycles, boats, submarines, aircraft, jet aircraft, spacecraft, trains, or other mobile platforms) as well as non-mobile electric systems (such as power plants, appliances, and photovoltaic solar devices). The phrase "vehicle" is broadly defined as any moving machine, including but not limited to: automobiles, trucks, motorcycles, boats, submarines, aircraft, spacecraft, trains, or other mobile platforms.

[0120] Figure 1A A cutaway perspective view of an example of a coaxial electrical cable 10 is shown. The cable 10 includes layers: a conductive axial center conductor 12 (e.g., a thick solid copper wire or a twisted thin copper wire); the conductive axial center conductor 12 is covered by a coaxial dielectric insulator 14; the coaxial dielectric insulator 14 is covered by a first conductive coaxial shield 16 (the first conductive coaxial shield 16 can include a woven array of conductive aluminum or copper wires); the first conductive coaxial shield 16 is optionally covered by a second conductive shield layer 18 (e.g., aluminum foil), which is ultimately covered by a dielectric coaxial jacket 20 (the dielectric coaxial jacket 20 can include a dielectric insulating material).

[0121] Figure 1B A simplified perspective view of an example of a coaxial electrical cable 10 is shown, with a portion of the center axial conductor 12 exposed at one end. In this example, the coaxial dielectric insulator 14, the conductive coaxial shield 16, and the dielectric coaxial jacket 20 have been partially stripped and removed, leaving an exposed length of the center axial conductor 12.

[0122] Figure 2A A schematic perspective cross-sectional view of an example of a rectangular AC choke 24 according to the present disclosure is shown. The choke 24 has a rectangular shape with an axial length = L (along the Z-axis direction). The choke 24 includes a hollow magnetic core 26 made of a ferrous magnetic material (e.g., a ferrous-containing material or a ferrite material, or a nanocrystalline ferrous amorphous ribbon material), the magnetic core 26 defining a rectangular bore 40 inside the magnetic core 26. Moving outward, the next layer includes a first thermally conductive material layer 28 (e.g., a thermally conductive paste). Moving outward, the next layer includes a dielectric separator 30 made of a dielectric material (e.g., polyamide, polyphenylene sulfide, epoxy, and / or polycarbonate, etc.). Moving outward, the next layer includes a second thermally conductive material layer 32 (e.g., a thermally conductive paste). Moving outward, the next layer includes a metal outer shell 34 (e.g., an aluminum alloy or a steel alloy, or a combination thereof). Moving outward, the next layer includes a third thermally conductive material layer 36 (e.g., a thermally conductive paste). Finally, the outermost layer of the choke 24 includes a dielectric outer jacket 38 made of an insulating material (e.g., polyamide, polyphenylene sulfide, epoxy, and / or polycarbonate, etc.).

[0123] Still referring toFigure 2A In some embodiments, the third thermally conductive material layer 36 (e.g., thermally conductive paste) and the dielectric outer jacket 38 can be optionally omitted. In this embodiment, this configuration makes the metal outer shell 34 the outermost layer.

[0124] Figure 2B A schematic perspective cross-sectional view of an example of a rectangular AC choke assembly 42 according to the present disclosure is shown, having an axial length = L (along the Z-axis direction), wherein three parallel coaxial electrical cables 44, 44' and 44" are disposed inside and pass through the bore 40 of the choke 24. In some embodiments, the remaining unused open space 22 between the coaxial electrical cables 44, 44' and 44" can be filled with a dielectric material.

[0125] Figure 3A A schematic perspective view of an example of a monolithic rectangular magnetic core 46 according to the present disclosure is shown, having an axial length = L (along the Z-axis direction) and four rounded corners 48, 48' and so on. The interior of the magnetic core 46 defines an axial bore 50.

[0126] Figure 3B A schematic perspective view of an example of a monolithic rectangular magnetic core assembly 52 according to the present disclosure is shown, having an axial length = L (along the Z-axis direction), four rounded corners 48, 48' and so on, and three parallel coaxial electrical cables 54, 54', 54" are disposed inside and pass through the axial bore 50 of the magnetic core 46. In some embodiments, the remaining unused open space 23 between the coaxial electrical cables 54, 54' and 54" can be filled with a dielectric material.

[0127] Figure 4A A schematic perspective cross-sectional view of an example of a rectangular AC choke 56 according to the present disclosure is shown, having an axial length = L (along the Z-axis direction), four rounded corners 57, 57' and so on. The choke 56 includes a hollow magnetic core 58 made of a magnetic material (e.g., a ferrite-based ferrite material, or a nanocrystalline ferrite-based amorphous ribbon material), the magnetic core 58 defining a rectangular axial bore 72 inside the magnetic core 58. Moving outward, the next layer includes a first thermally conductive material layer 60 (e.g., a thermally conductive paste). Moving outward, the next layer includes a dielectric spacer 62 made of a dielectric material (e.g., polyamide, polyphenylene sulfide, epoxy, and / or polycarbonate, and / or the like). Moving outward, the next layer includes a second thermally conductive material layer 64 (e.g., a thermally conductive paste). Moving outward, the next layer includes a metal outer shell 66 (e.g., an aluminum alloy or a steel alloy, or a combination thereof). Moving outward, the next layer includes a third thermally conductive material layer 68 (e.g., a thermally conductive paste). Finally, the outermost layer of the choke 56 includes a dielectric outer jacket 70 made of an insulating material (e.g., polyamide, polyphenylene sulfide, epoxy, and / or polycarbonate, and / or the like).

[0128] Still referring to Figure 4A In some embodiments, the third thermally conductive material layer 68 (e.g., thermally conductive paste) and the dielectric outer jacket 70 can be optionally omitted. In this embodiment, this configuration makes the metal outer shell 66 the outermost layer.

[0129] Figure 4B A schematic perspective cross-sectional view showing an example of a rectangular AC choke assembly 76 according to the present disclosure, having an axial length = L (along the Z-axis direction), with four rounded corners 57, 57', etc., and three parallel coaxial electrical cables 74, 74', and 74" disposed inside and passing through the internal axial bore 72 of the choke 56. In some embodiments, the remaining unused open space 25 between the coaxial electrical cables 74, 74', and 74" can be filled with a dielectric material.

[0130] Figure 5A A schematic perspective cross-sectional view showing an example of a circular AC choke 78 (having an axial length = L (along the Z-axis direction)) according to the present disclosure. The choke 78 includes a hollow circular magnetic core 80 made of a magnetic material (e.g., an iron-based ferrite material, or a nanocrystalline iron-based amorphous ribbon material), the core 80 defining a circular axial bore 94 inside the core 80. Moving outward, the next layer includes a first thermally conductive material layer 82 (e.g., a thermally conductive paste). Moving outward, the next layer includes a circular dielectric spacer 84 made of a dielectric material (e.g., polyamide, polyphenylene sulfide, epoxy, and / or polycarbonate, etc.). Moving outward, the next layer includes a second thermally conductive material layer 86 (e.g., a thermally conductive paste). Moving outward, the next layer includes a circular metal outer shell 88 (e.g., an aluminum alloy or a steel alloy, or a combination thereof). Moving outward, the next layer includes a third thermally conductive material layer 90 (e.g., a thermally conductive paste). Finally, the outermost layer of the choke 78 includes a circular dielectric outer jacket 92 made of an insulating material (e.g., polyamide, polyphenylene sulfide, epoxy, and / or polycarbonate, etc.).

[0131] Still referring to Figure 5A In some embodiments, the third thermally conductive material layer 90 (e.g., a thermally conductive paste) and the dielectric outer jacket 92 can be optionally omitted. In this embodiment, this configuration makes the metal outer shell 88 the outermost layer.

[0132] Figure 5B A schematic perspective cross-sectional view showing an example of a circular AC choke assembly 96 according to the present disclosure, where three parallel coaxial electrical cables 98, 98', and 98" are disposed inside and passing through the internal bore 94 of the choke 78. In some embodiments, the remaining unused open space 27 between the coaxial electrical cables 98, 98', and 98" can be filled with a dielectric material.

[0133] Figure 6A A schematic perspective cross-sectional view showing an example of a triangular AC choke 99 (with an axial length = L (along the direction of the Z-axis)) according to the present disclosure is shown. The choke 99 includes a hollow triangular magnetic core 100 made of a magnetic material (e.g., an iron-based ferrite material, or a nanocrystalline iron-based amorphous ribbon material), the magnetic core 100 defining a triangular axial bore 114 inside the magnetic core 100. Moving outward, the next layer includes a first thermally conductive material layer 102 (e.g., a thermally conductive paste). Moving outward, the next layer includes a triangular dielectric spacer 104 made of a dielectric material (e.g., polyamide, polyphenylene sulfide, epoxy, and / or polycarbonate, etc.). Moving outward, the next layer includes a second thermally conductive material layer 106 (e.g., a thermally conductive paste). Moving outward, the next layer includes a triangular metal housing 108 (e.g., an aluminum alloy or a steel alloy, or a combination thereof). Moving outward, the next layer includes a third thermally conductive material layer 110 (e.g., a thermally conductive paste). Finally, the outermost layer of the choke 99 includes a triangular dielectric outer sheath 112 made of an insulating material (e.g., polyamide, polyphenylene sulfide, epoxy, and / or polycarbonate, etc.).

[0134] Still referring to Figure 6A In some embodiments, the third thermally conductive material layer 110 (e.g., a thermally conductive paste) and the dielectric outer sheath 112 can be optionally omitted. In this embodiment, this configuration makes the triangular metal housing 108 the outermost layer.

[0135] Figure 6B A schematic perspective cross-sectional view showing an example of a triangular AC choke assembly 116 according to the present disclosure is shown, in which three parallel coaxial electrical cables 118, 118', 118" are disposed inside the internal axial bore 114 of the choke 100, and pass through the internal axial bore 114.

[0136] Figure 7A schematic top plan view showing an example of an AC choke assembly 120 according to the present disclosure, including an AC choke 130, in which three parallel coaxial electrical cables 122, 122' and 122" are disposed inside the choke 130 and pass through the choke 130 in the Z-axis direction. In this embodiment, the dielectric outer sheaths 124, 124', 124" of the coaxial electrical cables 122, 122' and 122" have been removed to expose the cut conductive coaxial shield ends 126, 126' and 126", respectively. The AC choke 130 can have a rectangular, circular or triangular cross-section, as shown previously. In this embodiment, an optional dielectric outer cover 132 surrounding the AC choke 130 is shown diagrammatically as a dashed line, indicating that the dielectric outer cover 132 is not a required feature. In this embodiment, the AC choke 130 is located in the middle portion along the Z-axis of the three coaxial electrical cables 122, 122' and 122". A metal housing 170 is disposed inside the AC choke 130. The cut conductive coaxial shield ends 126, 126' and 126" can be connected to the top (or bottom) of the metal housing 170. The cut conductive coaxial shield ends 126, 126' and 126" are discontinuous across the AC choke 130.

[0137] Figure 8A A schematic top plan view showing an example of an AC choke assembly 120 according to the present disclosure, Figure 7The AC choke assembly 120 includes a coaxial electrical cable 122 electrically and mechanically integrated together with an AC choke 130 of axial length = L (along the direction of the Z-axis). The coaxial electrical cable 122 includes an axial center conductor 164 surrounded by a coaxial dielectric insulator 172, which is surrounded by a conductive coaxial shield 128, which is covered by a dielectric coaxial jacket 124. In this embodiment, a short middle portion (longer than the axial length L) of the dielectric coaxial jacket 124 is cut and removed. Then, left and right end portions 129 and 129’ of the conductive coaxial shield 128 are cut in the middle section of the coaxial cable 122, and each of the left and right cut shield end portions 129 and 129’ are stripped from the coaxial dielectric insulator 172 while remaining connected to the coaxial shield 128. The cut shield end portions 129 and 129’ can then be electrically connected to the top (or bottom) of the left and right sides of the metal housing 170, respectively. The cut shield end portions 129 and 129’ can be connected to the metal housing 170 (which can be soldered and crimped) by soldering, screwing, laser welding, or using crimp connections. The coaxial dielectric insulator 172 can pass through the AC choke 130 in a continuous manner. Optionally, ferrules (not shown) can be used to connect the cut shield end portions 129 and 129’ to the metal housing 170.

[0138] Figure 8B FIG. 6 shows a schematic side cross-sectional view (section A-A) of an example of an AC choke assembly 120 according to the present disclosure. Figure 7A schematic side cross-sectional view (section A-A) of the example shown in FIG. 1, the AC choke assembly 120 includes a coaxial electrical cable 122 electrically and mechanically integrated together with an AC choke 130 of axial length = L (along the Z-axis direction). The coaxial electrical cable 122 includes an axial center conductor 164, which is surrounded by a coaxial dielectric insulator 172, which is surrounded by a conductive coaxial shield 128, which is covered by a dielectric coaxial jacket 124. In this embodiment, a short middle portion of the dielectric coaxial jacket 124 (longer than the axial length L) is cut and removed. Then, left and right end portions 129 and 129' of the conductive coaxial shield 128 are cut in the middle section of the coaxial cable 122, and each of the left and right cut shield end portions 129 and 129' are stripped from the coaxial dielectric insulator 172 while remaining connected to the coaxial shield 128. The cut shield end portions 129 and 129' can then be electrically connected between the left and right sides of the metal housing 170 and the dielectric divider 166, respectively. The coaxial dielectric insulator 172 can pass through the AC choke 130 in a continuous manner. The cut shield end portions 129 and 129' can be connected to the metal housing 170 (which can be brazed and crimped) by brazing, screw connections, laser welding, or using crimp connections. Optionally, ferrules (not shown) can be used to connect the cut shield end portions 129 and 129' to the metal housing 170.

[0139] Figure 9A A schematic top plan view showing an example of an AC choke assembly 160 according to the present disclosure, the AC choke assembly 160 includes an AC choke 142 attached to a traction drive unit (TDU) 144 or traction power inverter module (TPIM) 144, where three parallel coaxial electrical cables 136, 136', and 136" are disposed inside the AC choke 142 and pass through the AC choke 142 along the Z-axis direction. The short ends of the dielectric coaxial jacket 124 are cut and removed. Then, as the coaxial electrical cables 136, 136', and 136" enter the right side of the choke 142, the end portions of the conductive coaxial shields 138, 138', and 138" of the coaxial electrical cables 136, 136', and 136" are exposed by stripping the dielectric coaxial jacket 124, respectively. The exposed coaxial shield end portions 138, 138', and 138" can then be connected to the top (or bottom) of the metal housing 142. Note: the internal magnetic core 135 is shown as a dashed hidden line.

[0140] Figure 9BA schematic top view of an example of an AC choke assembly 160 according to the present disclosure is shown. The AC choke assembly 160 includes an AC choke 142 attached to a traction drive unit (TDU) 144 or a traction power inverter module (TPIM) 144, wherein three parallel coaxial electrical cables 136, 136', and 136" are disposed inside the AC choke 142 and pass through the AC choke 142 in the Z-axis direction. The short end of the dielectric coaxial sheath 124 is cut and removed. Then, as the coaxial electrical cables 136, 136', and 136" enter the right side of the choke 142, the conductive coaxial shield ends 138, 138', and 138" of the coaxial electrical cables 136, 136', and 136" are exposed by stripping the dielectric coaxial sheath 124, respectively. Then, the three coaxial shielding grounding rings 134, 134', and 134" are connected (e.g., crimped and / or brazed) to the exposed coaxial shielding ends 138, 138', and 138" respectively. The coaxial shielding grounding rings 134, 134', and 134" are also connected to the right side of the metal housing 142. Note: The internal magnetic core 135 is shown as a dashed hidden line.

[0141] Figure 10 The AC choke coil assembly 160 according to this disclosure is shown. Figure 9A The schematic side cross-sectional view (section BB) of the example shown indicates that the AC choke assembly 160 includes a coaxial electrical cable 136 electrically and mechanically integrated with an AC choke 142 attached to a TPIM or TDU power unit 144. In this embodiment, when the coaxial electrical cable 136 enters the right side of the choke 142, the conductive coaxial shield end 138 of the coaxial electrical cable 136 is exposed by removing the left end of the dielectric coaxial sheath 124. The short end of the conductive coaxial shield 138 is stripped from the coaxial dielectric insulator 145 and electrically connected to the top (or bottom) of the right side of the metal housing 170. The cut shield end 138 can be connected to the metal housing 170 by brazing, screwing, or using a crimp connection (which can be brazed and crimped). The metal housing 170 of the choke 142 is attached to the TPIM or TDU unit 144, and the central axial conductor 140 penetrates the right side of the TPIM or TDU unit 144 to make electrical contact with it. A coaxial dielectric insulator 145 may pass continuously through the AC choke 130.

[0142] Figure 11AA schematic top plan view showing an example of an AC choke 148 housed in a sheet metal housing 146 according to the present disclosure. The housing 146 includes a pair of parallel sheet metal plates 152 and 154 that encircle and securely hold the choke 148. The housing 146 also includes three bosses 149, 149', 149" each having a central hole 150, 150', and 150", respectively, for bolting the housing unit 146 to a base (not shown).

[0143] Figure 11B A schematic bottom plan view showing an example of an AC choke 148 housed in a sheet metal housing 146 according to the present disclosure. The housing 146 includes a pair of parallel sheet metal plates 152 and 154 that encircle and securely hold the choke 148. The housing 146 also includes three bosses 149, 149', 149" each having a central hole 150, 150', and 150", respectively, for bolting the housing unit 146 to a base (not shown).

[0144] Figure 11C A schematic front elevational view showing an example of an AC choke 148 housed in a sheet metal housing 146 according to the present disclosure. The housing 146 includes a pair of parallel sheet metal plates 152 and 154 that encircle and securely hold the choke 148. The housing 146 also includes bosses 149 and 149" each having a central hole 150 and 150", respectively, for bolting the housing unit 146 to a base (not shown).

[0145] Figure 11D A schematic side elevational view showing an example of an AC choke 148 housed in a sheet metal housing 146 according to the present disclosure. The housing 146 includes a pair of parallel sheet metal plates 152 and 154 that encircle and securely hold the choke 148. The housing 146 also includes two bosses 149', 149" each having a central hole 150, 150', respectively, for bolting the housing unit 146 to a base (not shown).

[0146] Figure 12A schematic front elevation view showing an example of a magnetic core 156 of an AC choke 180 according to the present disclosure. In this embodiment, the magnetic core 156 comprises a plurality of thin nanocrystalline ribbons wound in a rounded rectangular geometry, defining an axial bore 182 disposed inside the core 156. A stripped coaxial shield strip 158 is electrically connected to an upper surface (or lower surface) of the magnetic core 156. Optionally, a ferrule (not shown) can be used to connect the stripped coaxial shield strip 158 to the magnetic core 156. In some embodiments, no metal housing is used, and the electrically conductive coaxial shield strip 158 is electrically connected to the magnetic core 156 of the AC choke 180.

[0147] Figure 13 A schematic perspective view showing an example of a rounded triangular magnetic core 192 according to the present disclosure. In this embodiment, the rounded triangular magnetic core 192 has three rounded corners 193, 193’ and 193”, and an axial bore 194 disposed inside the magnetic core 192, and has an axial length L aligned with the Z-axis.

[0148] Figure 14 A schematic perspective view showing an example of a vehicle 1 having an AC choke assembly 160 according to the present disclosure. The vehicle 1 has a vehicle body 2 having four road wheels 3, 3’ and the like, and an AC choke assembly 160 connected to a traction drive unit (TDU) or traction power inverter module (TPIM) 144 connected to a traction drive motor (not shown).

[0149] In some embodiments, exposed surfaces of the AC choke are covered with a dielectric insulating material.

[0150] DETAILED DESCRIPTION and the accompanying drawings or figures are supportive and descriptive of the present teachings, but the scope of the present teachings is limited only by the claims. While some of the best modes and other embodiments for carrying out the present teachings have been described in detail, various alternative designs and embodiments exist for practicing the teachings defined in the appended claims. All of the embodiments and examples disclosed herein are non-limiting embodiments and non-limiting examples. The words “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably to indicate that there are one or more of the items.

Claims

1. An AC choke for reducing common-mode current and bearing current in an AC drive system, comprising: magnetic core; Axial bore defined by the magnetic core; Dielectric separators surrounding the magnetic core; as well as A metal casing surrounding the dielectric separator; and The dielectric separator electrically isolates the magnetic core from the metal casing.

2. The AC choke coil according to claim 1, further comprising: A first thermal interface material layer is disposed between the magnetic core and the dielectric separator; as well as A second thermal interface material layer is disposed between the dielectric separator and the metal housing.

3. The AC choke coil according to claim 2, further comprising: A dielectric outer sheath surrounding the metal casing; as well as A third thermal interface material layer is disposed between the metal casing and the dielectric outer sheath.

4. The AC choke coil according to claim 1, wherein, The exposed surface of the AC choke is covered with a dielectric insulating material.

5. The AC choke coil according to claim 1, in, The magnetic core comprises an iron-containing material selected from the group consisting of nanocrystalline iron-containing materials, ferrite materials, and / or combinations thereof; The dielectric separator comprises polyphenylene sulfide; and The metal casing comprises aluminum alloy and / or steel alloy and / or a combination thereof.

6. The AC choke coil according to claim 3, wherein, The dielectric outer sheath comprises polyphenylene sulfide.

7. The AC choke coil according to claim 1, wherein, The magnetic core can be rectangular, rounded rectangular, circular, triangular, or rounded triangular in shape.

8. The AC choke according to claim 1, further comprising at least one coaxial electrical cable disposed inside the bore of the magnetic core and passing through the bore.

9. An AC choke assembly for reducing common-mode current and bearing current in an AC drive system, comprising: (a) An AC choke, wherein the AC choke comprises: magnetic core; Axial bore defined by the magnetic core; Dielectric separators surrounding the magnetic core; and A metal casing surrounding the dielectric separator; The AC choke coil assembly further includes: (b) At least one coaxial electrical cable, said at least one coaxial electrical cable being disposed inside and passing through the axial bore of the magnetic core; The dielectric separator electrically isolates the magnetic core from the metal casing; and Wherein, the at least one coaxial electrical cable includes: (1) Axial center conductor; (2) A coaxial dielectric insulator surrounding the axial central conductor; (3) A conductive coaxial shield surrounding the coaxial dielectric insulator; and (4) A dielectric coaxial sheath surrounding the conductive coaxial shield.

10. A vehicle comprising: Vehicle body; One or more road wheels connected to the vehicle body; as well as An AC choke assembly connected to the vehicle body; The AC choke coil assembly includes: (a) AC choke, which includes: magnetic core; Axial bore defined by the magnetic core; Dielectric separators surrounding the magnetic core; and A metal casing surrounding the dielectric separator; (b) At least one coaxial electrical cable, said at least one coaxial electrical cable being disposed inside and passing through the axial bore of the magnetic core; and (c) A traction drive unit (TDU) or traction power inverter module (TPIM) connected to the AC choke coil; The dielectric separator electrically isolates the magnetic core from the metal casing. Wherein, the at least one coaxial electrical cable includes: (1) Axial center conductor; (2) A coaxial dielectric insulator surrounding the axial central conductor; (3) A conductive coaxial shield surrounding the coaxial dielectric insulator; and (4) A dielectric coaxial sheath surrounding the conductive coaxial shield; Wherein, the axial center conductor is connected to the TDU or TPIM; and The conductive coaxial shield is connected to the metal casing.

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