Hybrid excited rotary machine

Abstract

An electrified powertrain of a vehicle includes a battery pack linked to a traction power inverter module (TPIM) that converts a DC voltage from the battery pack to an AC voltage. A rotating electrical machine includes a stator excited by an AC voltage of a TPIM, surrounding a rotatable rotor core. The rotor core includes slots that accommodate conductive strips and permanent magnets, the conductive strips being positioned closer to the center of the rotor core. The conductive strip and the permanent magnet are separated by a gap within each slot. An annular end ring assembly is present at one end of the rotor core, characterized in that the terminal conductors are connected to a subset of the conductive strips and the secondary coil of the resolver. When the stator is energized, a rotor shaft connected to the rotor rotates. An electric machine powers a transmission coupled to the rotor shaft.

Description

Technical Field

[0001] The present disclosure relates to rotating electrical machines. More particularly, the present disclosure relates to hybrid-excitation (HE) rotating machines combining permanent magnet (PM) excitation and field excitation. Background Art

[0002] HE machines advantageously provide two sources of rotor magnetic fields. The rotor in such machines may typically include a field coil wound from small gauge wire, limiting the fill factor and increasing the complexity of rotor manufacturing. Due in part to the additional copper loss characteristics of the field coil, HE machines may exhibit relatively high heat and the potential for thermally induced demagnetization and reduced field strength of the permanent magnets.

[0003] HE machines with high fill factor, simpler manufacturing and heat resistant properties are desired. Summary of the invention

[0004] In one exemplary embodiment, the electric machine may include a stator and a rotor core surrounded by the stator and rotatable about an axis, the rotor core having axially opposite ends and a plurality of slots, each slot extending through the rotor core between the axially opposite ends and containing at least one corresponding electrical conductor and at least one corresponding permanent magnet, wherein the electrical conductor is radially inboard relative to the permanent magnet and extends beyond the axially opposite ends of the rotor core.

[0005] In addition to one or more features described herein, the electrical conductor may include a conductive strip.

[0006] In addition to one or more features described herein, the conductive strip may include a hairpin conductor.

[0007] In addition to one or more features described herein, at least one respective electrical conductor and at least one respective permanent magnet contained within each slot can be separated by a respective space.

[0008] In addition to one or more features described herein, the at least one respective permanent magnet contained within each slot may include a stack of permanent magnets.

[0009] In addition to one or more features described herein, at least one respective permanent magnet contained within each slot may include a respective first magnet and a respective second magnet, wherein the first magnet is intermediate the second magnet and the electrical conductor, the first magnet having a first temperature rating, and the second magnet having a second temperature rating that is less than the first temperature rating.

[0010] In addition to one or more features described herein, at least one corresponding permanent magnet contained within each slot may include a corresponding first magnet and a corresponding second magnet, wherein the first magnet is intermediate the second magnet and the electrical conductor, the first magnet has a first coercive force, and the second magnet has a second coercive force less than the first coercive force.

[0011] In addition to one or more features described herein, the space separating the electrical conductors and the permanent magnets may include a cooling passage within the rotor core.

[0012] In addition to one or more features described herein, the space separating the electrical conductors and the permanent magnets may contain a thermal insulator.

[0013] In addition to one or more features described herein, the conductive strips may be hollow.

[0014] In addition to one or more features described herein, slots may be open at the periphery of the rotor core sufficient for radial insertion of electrical conductors.

[0015] In addition to one or more features described herein, the electric machine may also include a cylindrical containment sleeve surrounding the rotor core at a periphery of the rotor core.

[0016] In addition to one or more features described herein, the electric machine may include an annular end ring assembly at one end of the rotor core, the annular end ring assembly including a first terminal conductor galvanically coupled to a first subset of the conductive bars and a second terminal conductor galvanically coupled to a second subset of the conductive bars.

[0017] In addition to one or more of the features described herein, the annular end ring assembly may also include a secondary coil of a rotary transformer.

[0018] In addition to one or more features described herein, the annular end ring assembly may radially surround the conductive bars, wherein the conductive bars extend beyond one end of the rotor core.

[0019] In addition to one or more features described herein, the annular end ring assembly may be radially surrounded by conductive bars, wherein the conductive bars extend beyond one end of the rotor core.

[0020] In another exemplary embodiment, the electric machine may include a stator, a rotor core surrounded by the stator and rotatable about an axis, the rotor core having axially opposite ends and a plurality of slots, each slot extending through the rotor core between the axially opposite ends and containing at least one corresponding conductive bar and at least one corresponding permanent magnet, wherein the conductive bar is radially inward relative to the permanent magnet and extends beyond the axially opposite ends of the rotor core, and the at least one corresponding conductive bar and the at least one corresponding permanent magnet contained in each slot are separated by corresponding spaces, and an annular end ring assembly at one end of the rotor core, the annular end ring assembly containing first terminal conductors electrically coupled to a first subset of the conductive bars and second terminal conductors electrically coupled to a second subset of the conductive bars.

[0021] In addition to one or more of the features described herein, the annular end ring assembly may also contain a secondary coil of a rotary transformer.

[0022] In addition to one or more features described herein, at least one corresponding permanent magnet contained within each slot may include a corresponding first magnet and a corresponding second magnet, wherein the first magnet is intermediate the second magnet and the conductive strip, the first magnet has a first coercive force, and the second magnet has a second coercive force less than the first coercive force.

[0023] In yet another exemplary embodiment, an electrified powertrain for a vehicle may include a battery pack, a traction power inverter module (“TPIM”) connected to the battery pack and configured to change a direct current (“DC”) voltage from the battery pack to an alternating current (“AC”) voltage, and a rotating electric machine including a stator excited by the AC voltage from the TPIM, a rotor core surrounded by the stator and rotatable about an axis, the rotor core having axially opposite ends and a plurality of slots, each slot extending through the rotor core between the axially opposite ends and containing at least one corresponding conductive bar and at least one corresponding permanent magnet, wherein the conductive bar The rotor core includes a first slot and a second ...

[0024] The above features and advantages and other features and advantages of the present disclosure are apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, advantages and details appear, by way of example only, in the following detailed description, which refers to the accompanying drawings, in which:

[0026] Figure 1 An electrified powertrain according to one or more embodiments is shown;

[0027] Figure 2 illustrates various features of a hybrid electric machine rotor according to one or more embodiments;

[0028] Figure 3A and 3B illustrates various features of a hybrid electric machine rotor according to one or more embodiments;

[0029] Figure 4 illustrates various end features of a hybrid electric machine rotor according to one or more embodiments;

[0030] Figure 5A and 5B illustrates various magnetic operations of a hybrid electric machine rotor according to one or more embodiments; and

[0031] Figure 6 Alternative configurations of hybrid electric machine rotors are shown in accordance with one or more embodiments. DETAILED DESCRIPTION

[0032] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. Throughout the drawings, corresponding reference numerals indicate identical or corresponding parts and features. The description of components and features in one drawing is understood to apply to components and features in other drawings sharing the same reference numeral to the extent that such components and features cannot be otherwise distinguished by one of ordinary skill in the art by inspection of the drawings or by the additional written description herein.

[0033] Referring to the drawings, in which like reference numerals designate the same or similar parts throughout the several views, Figure 1An electrified powertrain 10 (e.g., for use on an exemplary motor vehicle 11) is schematically depicted in FIG. 1 . The powertrain 10 includes a rotating electric machine 12 having a rotor 12R and a stator 12S. The rotor 12R may include internal permanent magnets and a direct current (DC) field winding as a source of a rotor magnetic field. When the stator 12S is energized, the rotor 12R provides motor torque to a transmission 20 (e.g., a stepper gear automatic transmission). Although omitted for simplicity of illustration, the electrified powertrain 10 may also include an internal combustion engine configured to generate engine torque. When so equipped, the generated engine torque may be selectively provided to the transmission 20 alone or in combination with the motor torque from the motor 12.

[0034] when Figure 1 When the vehicle 11 is implemented as a hybrid electric vehicle, the motor 12 and / or the engine can provide power to the transmission 20. Alternatively, the vehicle 11 can be a battery electric vehicle, in which case the transmission 20 can be powered solely by the motor torque from the motor 12. The disclosed improvements relate to the configuration of the motor 12 and can be implemented in hybrid electric vehicle (HEV) and electric vehicle (EV) embodiments of the vehicle 11, without limitation, as well as in non-vehicle applications such as power plants, hoists, mobile platforms, and robots.

[0035] Continue to refer Figure 1 In an exemplary vehicle 11 of FIG. 1 , the electrified powertrain 10 may include an alternating current (AC) voltage bus 13. The AC voltage bus 13 may be selectively energized via a traction power inverter module (TPIM) 28, which is DC coupled to a high voltage (HV) battery pack 24, such as lithium-ion, lithium-sulfur, nickel-metal hydride, or other high energy voltage source. The AC voltage bus 13 provides an AC bus voltage (VAC) and conducts AC current to or from the motor 12. When operating in a drive or motor drive mode, the motor torque from the energized motor 12 is transmitted to a rotor shaft 125 of the rotor 12R, where the rotor shaft 125 is journaled, splined, or otherwise connected to the rotor 12R. The motor torque is then directed to a coupled load, such as a transmission 20 and / or one or more road wheels 22.

[0036] The HV battery pack may be DC coupled to the TPIM 28 via a relatively high DC voltage bus (e.g., DC link) 15 at a relatively high DC voltage (VDC). The electrified powertrain 10 may also include a DC-DC converter 26 configured to reduce or increase the relatively high DC bus voltage VDC as needed. The DC-DC converter 26 is connected between the battery pack 24 and the relatively low DC voltage bus 16. In some configurations, an auxiliary battery pack 124 may be connected to the DC-DC converter 26 across the relatively low DC voltage bus 16. The auxiliary battery pack 124 may be implemented as a lead-acid battery or a battery composed of another application-appropriate chemistry and is configured to store, for example, a 12-15V auxiliary voltage (VDC). AUX ) or supplying, for example, a 12-15V auxiliary voltage (V AUX ).

[0037] The rotor 12R of the electric machine 12 is positioned adjacent to the stator 12S and separated from the stator 12S by an air gap. The stator 12S and the rotor 12R may be constructed from a stack of thin laminations (e.g., electrical steel or another ferrous material, with each lamination typically being about 0.2 mm-0.5 mm thick, as will be understood by one of ordinary skill in the art). The laminations may be cut into their finished shape by a punch and die, or may be cut by a laser or by wire electrical discharge machining.

[0038] Figure 1 The rotor 12R schematically shown in the figure includes internal rotor slots, which are characterized by gaps in the electrical steel of the laminations. Such rotor slots can provide flux barriers inside the rotor 12R and can include other rotor features as further described herein. According to certain embodiments, the rotor slots can be partially or completely filled with a combination of permanent magnets (PM) and electrical conductors. The electrical conductors of the rotor 12R operate as field windings to strategically generate magnetic fields within the rotor 12R. The electrical conductors can be powered by a DC power supply, such as from a high DC voltage bus 15 via a rotary transformer 29.

[0039] Figure 2 Depicts the rotation of a rotating machine according to the hybrid excitation (HE) Figure 1 12R of the rotor 12R. For simplicity and clarity of description, Figure 2The depiction in represents one half of the rotor core 201 divided by the axis of rotation 203 of the rotor 12R. The rotor core 201 can be constructed from a stack of thin laminations (e.g., electrical steel or another ferrous material, with each lamination typically being about 0.2 mm-0.5 mm thick, as will be understood by one of ordinary skill in the art). The laminations can be cut into their finished shape by a punch and die, or can be cut by a laser or by wire electrical discharge machining. The rotor core 201 can alternatively be manufactured, such as by molding from sintered powder metal and a binder under heat and pressure. The stator according to a non-limiting exemplary embodiment is arranged concentrically around the rotor 12R such that the rotor 12R is surrounded by the stator 12S. In such an embodiment, the air gap G is a radial air gap, and the motor 12 is implemented as a radial flux machine. However, other embodiments can be implemented in which the relative positions of the rotor 12R and the stator 12S are reversed. For consistency of illustration, the rotor 12R will be described here as being radially located within the stator 12S. Figure 1 The present invention further provides an embodiment of the present invention without limiting the structure to this configuration.

[0040] Figure 1 The stator 125 is not shown in further detail, but may include radially protruding stator teeth extending inwardly from a cylindrical stator core. That is, the stator teeth extend from the stator core toward the rotor 12R. The inner diameter surface of the stator 12S is the radially innermost surface of the stator teeth, which faces or opposes the outer peripheral surface 205 of the rotor 12R in a spaced adjacent manner to form an air gap G (see Figure 1 ). Adjacent stator teeth are separated from each other by corresponding stator slots, as will be understood by one of ordinary skill in the art. The stator slots enclose electrical conductors, typically copper wires, copper rods, or hairpin-shaped conductors. Such conductors together form the stator windings. When the stator windings are made of Figure 1 When the multi-phase output voltage of the TPIM 28 is sequentially energized, a rotating stator magnetic field is generated. The stator magnetic poles formed by the resulting rotating stator magnetic field interact with the rotor magnetic poles to rotate the rotor 12R about the rotation axis 203.

[0041] exist Figure 2In an HE rotating machine embodiment, the rotor core 201 may include a plurality of slots 207 extending axially through the rotor core 201 between opposite ends 209 of the rotor core 201. The slots may be substantially axially aligned between the opposite ends 209 of the rotor core, although the actual alignment may be skewed as known in the art. The slots 207 may be substantially radially aligned, although the actual alignment may be offset from true radial alignment, as known in the art. References herein to radial alignment or substantially radial alignment of slots, permanent magnets, or electrical conductors are understood to refer to true radial alignment or skewed radial alignment as known to those skilled in the art. In one embodiment, each slot 207 may include an electrical conductor 211 and a permanent magnet 213. The permanent magnet 213 may be continuous or segmented through the axial length of the slot 207. The electrical conductor 211 extends continuously through the axial length of the slot 207 and may extend axially beyond the opposite ends 209 of the rotor core 201, as known in the art. Figure 2 The electrical conductor 211 and the permanent magnet 213 are arranged in the slot 207 so that the electrical conductor 211 is located below or radially inside relative to the permanent magnet 213.

[0042] The permanent magnets 213 may be collectively referred to herein as rotor magnets, and may be comprised of, for example, ferrite, neodymium-iron-boron, samarium-cobalt, aluminum-nickel-cobalt, etc., or another application-appropriate material as discussed in further detail herein. The rotor magnets in this embodiment are embedded within corresponding slots 207 within the stack of individual steel laminations of the rotor core 201. The number, type, location, and / or relative orientation of the rotor magnets ultimately affects the magnitude and distribution of the magnetic flux in the ferrous material of the motor 12. Additionally, when viewed axially (e.g., Figure 3A and Figure 3B ), the rotor magnets may be uniformly distributed circumferentially. In one embodiment, the magnetic poles of the rotor magnets may be axially aligned. In one embodiment, the magnetic poles of the rotor magnets may be circumferentially aligned. In one embodiment, the magnetic poles of the rotor magnets may be radially aligned.

[0043] Figure 3A and Figure 3B Depicts the Figure 2 An end view of the rotor core viewed along axis of rotation 203 is shown. Figure 3A and 3B A number of different embodiments of the slot 207 structure, electrical conductor 211 and permanent magnet 213 are shown. Figure 3A Mainly depicted are exemplary embodiments of different electrical conductor 211 and permanent magnet 213 arrangements aligned within true radially aligned slots 207 . Figure 3B Exemplary embodiments of different radial and skewed radial slots 207 and alignment of electrical conductors 211 and permanent magnets 213 are primarily depicted.

[0044] exist Figure 3A, the slot positions are labeled A to G only for ease of reference to different exemplary embodiments. Starting from slot position A, the slot 207 contains an arrangement of a permanent magnet 213 and an electrical conductor 211 radially inside the permanent magnet 213. Space 301 separates the permanent magnet 213 and the electrical conductor 211. The electrical conductor 211 is shown as a single conductive strip. The conductive strip can be any suitable conductor, such as but not limited to copper, aluminum or brass. The conductive strip can be manufactured using any suitable process, including but not limited to stamping, rolling, laser cutting, casting, extrusion, etc. In the embodiment at slot position A, the conductive strip is solid. Space 301 can be an air gap, or can be filled with an insulator, such as but not limited to mineral wool or polyurethane. Space 301 can also provide a channel for circulating a pressurized coolant (such as lubricating oil or air). The slot 207 at position A is a closed slot having a bridge 303 of the rotor core 201 material at the outer peripheral surface 205 of the rotor core 201. The bridge 303 in the embodiment at slot location A may prevent radial insertion of the electrical conductor 211 and the permanent magnet 213 , thereby limiting rotor core 201 manufacturing to axial insertion.

[0045] At slot position B, slot 207 includes an arrangement of permanent magnet 213 and electrical conductor 211 radially inside permanent magnet 213. Space 301 separates permanent magnet 213 and electrical conductor 211. Electrical conductor 211 is shown as a single conductive strip. The conductive strip can be any suitable conductor, such as but not limited to copper, aluminum or brass. The conductive strip can be manufactured using any suitable process, including but not limited to stamping, rolling, laser cutting, casting, extrusion, etc. In the embodiment at slot position B, the conductive strip is hollow with a central channel 305 passing therethrough. The channel can carry a pressurized coolant, such as lubricating oil or air. Space 301 can be an air gap, or can be filled with an insulator, such as but not limited to mineral wool or polyurethane. Space 301 can also provide a channel for circulating a coolant such as lubricating oil. Slot 207 at position B is an open slot having a break 307 in the bridge of the rotor core 201 material at the outer peripheral surface 205 of the rotor core 201. The break 307 in the embodiment at slot location B may be too small for radial insertion of the electrical conductor 211 and permanent magnet 213 , thus limiting rotor core 201 manufacturing to axial insertion.

[0046] At slot position C, slot 207 includes an arrangement of permanent magnet 213 and electrical conductor 211 radially inside permanent magnet 213. Space 301 separates permanent magnet 213 and electrical conductor 211. Electrical conductor 211 is shown as first conductive strip 211A and second conductive strip 211B. The conductive strip can be any suitable conductor, such as but not limited to copper, aluminum or brass. The conductive strip can be manufactured using any suitable process, including but not limited to stamping, rolling, laser cutting, casting, extrusion, etc. In the embodiment at slot position C, the conductive strip is solid. Space 301 can be an air gap, or can be filled with an insulator, such as but not limited to mineral wool or polyurethane. Space 301 can also provide a channel for circulating a coolant such as lubricating oil. The slot 207 at position C is an open slot having a break 309 in the bridge of the rotor core 201 material at the outer peripheral surface 205 of the rotor core 201. The break 309 in the embodiment at slot location C may be large enough for radial insertion of the electrical conductor 211 and the permanent magnet 213. In an embodiment, when the break 309 does not provide a retaining feature on the permanent magnet 213, the non-magnetic cylindrical sleeve 310 may surround the rotor core 201.

[0047] At the slot position D, the slot 207 includes an arrangement of a permanent magnet 213 and an electrical conductor 211 radially inside the permanent magnet 213. The space 301 separates the permanent magnet 213 and the electrical conductor 211. The electrical conductor 211 is shown as a plurality of electrical conductors 211, such as hairpin conductors. The hairpin conductors can be any suitable conductor, such as but not limited to copper, aluminum or brass. The hairpin conductors can be manufactured using any suitable process, including but not limited to extrusion and forming. In the embodiment at the slot position D, the hairpin conductors are solid. The space 301 can be an air gap, or can be filled with an insulator, such as but not limited to mineral wool or polyurethane. The space 301 can also provide a channel for circulating a coolant such as lubricating oil. The hairpin conductors can be inserted radially or axially, depending on the presence and size of any breaks in the bridge of the rotor core 201 material at the outer peripheral surface 205 of the rotor core 201.

[0048] At slot position E, slot 207 includes an arrangement of permanent magnet 213 and electric conductor 211 radially inside permanent magnet 213. Space 301 separates permanent magnet 213 and electric conductor 211. Electric conductor 211 is shown as a single conductive strip. The conductive strip can be any suitable conductor, such as but not limited to copper, aluminum or brass. The conductive strip can be manufactured using any suitable process, including but not limited to stamping, rolling, laser cutting, casting, extrusion, etc. In the embodiment at slot position E, the conductive strip is solid. In the space 301 between electric conductor 211 and permanent magnet 213, a closed channel 311 is formed in rotor core 201. Closed channel 311 can provide a channel for circulating pressurized coolant (such as lubricating oil or air). The conductive strip and permanent magnet 213 can be inserted radially or axially, depending on the presence and size of any break in the bridge of rotor core 201 material at the outer peripheral surface 205 of rotor core 201.

[0049] At slot position F, slot 207 includes an arrangement of permanent magnet 213 and electric conductor 211 radially inside permanent magnet 213. Space 301 separates permanent magnet 213 and electric conductor 211. Electric conductor 211 is shown as a single conductive strip. The conductive strip can be any suitable conductor, such as but not limited to copper, aluminum or brass. The conductive strip can be manufactured using any suitable process, including but not limited to stamping, rolling, laser cutting, casting, extrusion, etc. In the embodiment at slot position F, the conductive strip is solid. A closed channel 313 is provided in rotor core 201 in space 301 between electric conductor 211 and permanent magnet 213. Closed channel 313 can be a pipe or tube of any suitable cross section. Closed channel 313 can provide a channel for circulating pressurized coolant (such as lubricating oil or air). The conductive strip and permanent magnet 213 can be inserted radially or axially, depending on the presence and size of any break in the bridge of rotor core 201 material at outer peripheral surface 205 of rotor core 201.

[0050] At slot position G, slot 207 includes an arrangement of permanent magnet 213 and electric conductor 211 radially inward of permanent magnet 213. Permanent magnet 213 is shown as first permanent magnet 213A and second permanent magnet 213B. First permanent magnet 213A is located between second permanent magnet 213B and electric conductor 211. In one embodiment, first permanent magnet 213A may have a first temperature rating less than the temperature rating of second permanent magnet 213B. In one embodiment, first permanent magnet 213A may have a first coercive force less than the coercive force of second permanent magnet 213B. Space 301 separates permanent magnet 213 and electric conductor 211. Electric conductor 211 is shown as a single conductive strip. Conductive strip may be any suitable conductor, such as but not limited to copper, aluminum or brass. Conductive strip may be manufactured using any suitable process, including but not limited to stamping, rolling, laser cutting, casting, extrusion, etc. In the embodiment at slot position G, conductive strip is solid. Space 301 may be an air gap, or may be filled with an insulator, such as, but not limited to, mineral wool or polyurethane. Space 301 may also provide a passage for circulating a pressurized coolant, such as lubricating oil or air. Conductive bars and permanent magnets 213 may be inserted radially or axially, depending on the presence and size of any breaks in the bridges of rotor core 201 material at outer peripheral surface 205 of rotor core 201.

[0051] exist Figure 3B , adjacent groups of magnets 213 and electrical conductors 211 are labeled 325, 335, 345, and 355 for ease of reference to different exemplary embodiments. These groups may correspond to pole pairs found, for example, in an internal permanent magnet rotor. The dashed line corresponds to a radius passing through the rotor core 201, which corresponds to the approximate position distribution of the permanent magnets 213 and electrical conductors 211 pairs on one side of the group providing the magnetic pole pairs as described above. The slots 207 are shown to include corresponding spaces 301. The slots may be formed with ledges for supporting the permanent magnets 213 and electrical conductors 211, as shown in the exemplary embodiments of groups 325 and 335. The slots may be formed without ledges for supporting the permanent magnets 213 and electrical conductors 211, as shown in the exemplary embodiments of groups 345 and 355. Group 325 depicts a pair of magnets 213 that are radially skewed and a pair of electrical conductors 211 that are also radially skewed. In group 325, the permanent magnets 213 and the electrical conductor pairs are skewed at an equivalent angle. Group 335 depicts a pair of magnets 213 that are truly radially aligned and a pair of electrical conductors 211 that are radially skewed. Group 345 depicts a pair of magnets 213 that are radially skewed and a pair of electrical conductors 211 that are truly radially aligned. Group 355 depicts a pair of magnets 213 that are radially skewed and a pair of electrical conductors 211 that are also radially skewed. In group 355, the permanent magnets 213 are skewed at a greater angle than the electrical conductors 211.

[0052] Out of Figure 4For the purpose of the following description of the embodiments, it is assumed that Figure 2 A general embodiment of a HE rotating machine of the present invention is provided, wherein the electrical conductor 211 is a continuous conductive bar extending through the axial length of the slot 207 and extending axially beyond the opposite end 209 of the rotor core 201. In one embodiment, the annular end ring assembly 401 may include two or more terminal conductors 403 for electrically coupling to respective subsets of the conductive bars 211. The terminal conductors 403 may be implemented, for example, as copper end rings having radially extending features electrically coupled to the subsets of the conductive bars, such as Figure 4 Schematically shown in . Such copper end rings can be stacked axially and separated by insulating rings. The permanent connection between the copper end rings and the conductive bars can be by brazing, brazing, laser welding, etc. The end ring assembly 401 is depicted as being radially outside the conductive bars and surrounding the conductive bars, but an annular end ring assembly 407 shown as being surrounded by the conductive bars is alternatively placed. In an embodiment where the electrical conductor is a hairpin conductor, the hairpin conductor can be pre-formed before insertion, thereby eliminating the need for a conductive path end ring at one end of the rotor core. However, even the end rings on the pre-formed side can benefit from the structural reinforcement of the non-conductive end ring assembly. In one embodiment, two arrangements of the end ring assemblies 401 and 407 can be adopted. The end ring assembly can integrate the secondary coil 409 of the rotary transformer for providing power to the electrical conductor 211 to generate a desired magnetic field response to the current flowing through the electrical conductor 211. A fixed primary winding (not shown) can inductively link power to the secondary coil 409 in one or both of the end ring assemblies. Utilizing end ring assembly 407 may advantageously support a more compact rotary transformer, where the primary coil may be radially inward of secondary coil 409. Similar end ring assembly 406 may be used on the opposite axial side of the rotor to short circuit all electrical conductors 211 or individual subsets for added flexibility and freedom.

[0053] Figure 5A and 5B An exemplary rotor core 201 and a plurality of electrical conductors 211 and permanent magnets 213 are shown, as previously described herein. In the illustrated embodiment, the exemplary permanent magnets have north poles (N) and south poles (S) that are circumferentially aligned as shown. In operation, the magnetic field from the permanent magnets 213 includes a PM flux path 503 between the poles, which includes radially aligned components as shown. The radially aligned PM flux path 503 may include a radially outward path that cuts through the air gap G and a radially inward path that passes through the guard iron 507 of the rotor core 201. The exemplary energized electrical conductors 211 may selectively carry current out of the page ( Figure 5A ) or carried to the page ( Figure 5B ), thereby showing the electromagnetic (EM) field from the exemplary electrical conductor 211 in the EM flux path 505 around the electrical conductor 211 according to the right-hand rule. Figure 5AIn the case where current leaves the page through the exemplary excited electrical conductor 211, the EM field is in the same direction as the PM field in the air gap G, resulting in a net magnetic field enhancement across the air gap G. Figure 5B In the case where current enters the page through the exemplary excited electrical conductor 211, the EM field is in the opposite direction to the PM field in the air gap G, resulting in a net magnetic field weakening across the air gap G.

[0054] Figure 6 An alternative embodiment of a rotor core 201 similar to a wound salient pole rotor is shown. Slots 207 are depicted as being on each side of separator 601 and defined between separator 601 and rotor core 201. As depicted, the cross-section of slot 207 may be open toward the air gap. Thus, in order to increase the filling factor, slot 207 may include multiple electrical conductors 211 having various cross-sections. The electrical conductor may be a strip including a hairpin conductor, or may be a wound wire having separator 601 providing a winding column. Permanent magnet 213 may have magnetic poles aligned radially as depicted. The magnetic field in the air gap G may be selectively enhanced or weakened by the direction of the current passing through electrical conductor 211. Permanent magnet 213 may be a single-piece rectangular cross-section as shown, or may be a trapezoidal or multi-piece stacked different cross-sections like electrical conductors to improve the filling factor.

[0055] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to also include the plural forms, unless the context clearly indicates otherwise. It will be further understood that when used in this specification, the terms "include" and / or "comprise" specify the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements and / or groups thereof.

[0056] All numerical values ​​herein are assumed to be modified by the term "about", whether explicitly stated or not. For purposes of this disclosure, ranges may be expressed as from "about" one particular value to "about" another particular value. The term "about" generally refers to a numerical range that one skilled in the art would consider equivalent to the numerical value, having the same function or result, or generally being reasonably within the manufacturing tolerance of the numerical value. Similarly, the numerical values ​​set forth herein are provided as non-limiting examples and may be nominal values, it being understood that actual values ​​may differ from the nominal values ​​depending on the environment, design and manufacturing tolerances, age, and other factors.

[0057] When an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element, or there can be intervening elements. Conversely, when an element is referred to as being "directly on" another element, there are no intervening elements. Therefore, unless explicitly described as "directly," when describing a relationship between a first element and a second element in the above disclosure, the relationship can be a direct relationship between the first element and the second element without other intervening elements, but can also be an indirect relationship between the first element and the second element with one or more intervening elements (either spatially or functionally) present.

[0058] One or more steps within the method may be performed in a different order (or simultaneously) without changing the principles of the present disclosure. In addition, although each embodiment is described above as having certain features, any one or more of those features described with respect to any embodiment of the present disclosure may be implemented in and / or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and the permutation of one or more embodiments with respect to each other is still within the scope of the present disclosure.

[0059] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0060] Unless stated to the contrary herein, all test standards are the most current standards in effect as of the filing date of this application or, if priority is claimed, the filing date of the earliest priority application in which the test standards appear.

[0061] Although the above disclosure has been described with reference to exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted for its elements without departing from its scope. In addition, many modifications may be made to adapt specific circumstances or materials to the teachings of the disclosure without departing from the basic scope of the disclosure. Therefore, it is intended that the disclosure is not limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. A motor, comprising: stator; as well as A rotor core is surrounded by the stator and is rotatable about an axis, the rotor core having axially opposite ends and a plurality of slots, each slot extending through the rotor core between the axially opposite ends and containing at least one corresponding electrical conductor and at least one corresponding permanent magnet, wherein the electrical conductor is located radially inwardly relative to the permanent magnet and extends beyond the axially opposite ends of the rotor core.

2. The electric machine of claim 1, wherein the electrical conductors comprise conductive bars.

3. The electric machine of claim 1, wherein at least one respective electrical conductor and at least one respective permanent magnet contained within each slot are separated by respective spaces.

4. The electric machine of claim 1 , wherein at least one respective permanent magnet contained within each slot comprises a respective first magnet and a respective second magnet, wherein the first magnet is intermediate the second magnet and the electrical conductor, the first magnet having a first temperature rating, and the second magnet having a second temperature rating less than the first temperature rating.

5. The electric machine of claim 1 , wherein at least one corresponding permanent magnet contained in each slot comprises a corresponding first magnet and a corresponding second magnet, wherein the first magnet is intermediate the second magnet and the electrical conductor, the first magnet has a first coercive force, and the second magnet has a second coercive force that is less than the first coercive force.

6. The electric machine of claim 3, wherein the space separating the electrical conductors and the permanent magnets comprises a cooling channel within the rotor core.

7. The electric machine of claim 3, wherein the space separating the electrical conductor and the permanent magnet contains a thermal insulator.

8. The electric machine of claim 2 further comprising an annular end ring assembly at one end of the rotor core, the annular end ring assembly containing a first terminal conductor galvanically coupled to a first subset of the conductive bars and a second terminal conductor galvanically coupled to a second subset of the conductive bars.

9. The electric machine of claim 8, wherein the annular end ring assembly further comprises a secondary coil of a rotary transformer.

10. The electric machine of claim 9, wherein the annular end ring assembly is radially surrounded by the conductive bars, wherein the conductive bars extend beyond an end of the rotor core.

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