Hybrid bar-and line-type conductor combination for high-speed electric motors

Abstract

The invention relates to a hybrid bar-type and wire-type conductor combination for a high-speed electric motor. An electric machine having both a bar-type conductor and a wire-type conductor, a method for manufacturing / using such an electric machine, and a vehicle equipped with such an electric machine are presented. An electric machine, such as a traction motor or generator, includes an outer housing, a stator fixedly mounted to the housing, and a rotor movably mounted to the housing and spaced apart from the stator across an air gap. A plurality of magnets, such as permanent magnet blocks, are mounted on or in slots of the rotor (or stator). A set of electromagnetic conductors extends through each radially elongated slot of the stator (or rotor). Each conductor set includes a set of solid wire or strands of wire type conductors positioned adjacent to the air gap. A group-pin-shaped or I-pin strip-shaped conductor is radially spaced from the air gap and positioned adjacent to the wire-shaped conductor. The strip-shaped conductor has a cross-sectional area / shape different from the cross-sectional area / shape of the linear conductor.

Description

Technical Field

[0001] The present disclosure relates generally to electric machines. More specifically, aspects of the present disclosure relate to electromagnetic conductors for multi-phase permanent magnet traction motors for hybrid electric and all-electric vehicle powertrains. Background Art

[0002] The motor vehicles currently produced, such as modern automobiles, are initially equipped with a powertrain that operates to propel the vehicle and power the vehicle's onboard electronics. For example, in automotive applications, the vehicle powertrain is typically represented by a prime mover that transmits drive torque to the final drive system (e.g., differential, axle, corner module, wheel, etc.) of the vehicle through an automatic or manually shifted power transmission. Due to its immediate availability, relatively light weight, and overall efficiency, historically automobiles have been powered by reciprocating piston internal combustion engine (ICE) components. As some non-limiting examples, such engines include compression ignition (CI) diesel engines, spark ignition (SI) gasoline engines, two-stroke, four-stroke, and six-stroke architectures, and rotary engines. On the other hand, hybrid electric and all-electric vehicles (collectively referred to as "electrically driven vehicles") utilize alternative power sources to propel the vehicle, and therefore minimize or eliminate dependence on fossil fuel-based engines for traction power.

[0003] A fully electric vehicle (FEV), commonly known as an "electric vehicle," is an electrically driven vehicle configuration that completely omits the internal combustion engine and accompanying peripheral components from the powertrain system, relying instead on a rechargeable energy storage system (RESS) and traction motors for vehicle propulsion. In a battery-based FEV, the engine components, fuel supply system, and exhaust system of an ICE-based vehicle are replaced by a single or multiple traction motors, rechargeable battery cells, and battery cooling and charging hardware. In contrast, the powertrain of a hybrid electric vehicle (HEV) employs a variety of traction power sources to propel the vehicle, most commonly an internal combustion engine component operating in conjunction with a battery-powered or fuel cell-powered traction motor. Because a hybrid electric drive vehicle is able to derive its power from sources other than the engine, the HEV engine can be fully or partially shut down while the vehicle is propelled by the electric motor. Summary of the invention

[0004] There are three main types of electric motors used for traction motors in modern electric drive vehicle powertrains: brushless direct current (BLDC) permanent magnet (PM) motors, brushless asynchronous alternating current (AC) motors, and multi-phase synchronous ACPM motors. Permanent magnet motors have a variety of operating characteristics that make them more attractive for use in vehicle propulsion applications when compared to their available counterparts, including high efficiency, high torque, high power density, and long constant power operating range. A traction motor is an electric motor that converts electrical energy into rotational mechanical energy to propel a vehicle. Many traction motors include: a stator with multi-phase electromagnetic windings, such as conductive "hairpin" bars; and a rotatable rotor that carries magnets in a certain design pattern, such as surface-mounted or internally mounted permanent magnets. PM motors can be classified as AC or DC, rotary or linear, and radial flux or axial flux. In a radial flux PM motor design, the rotor carrying the magnets can be coaxially nested within the stator, or can surround the stator. PM motors can also adopt an axial flux arrangement structure, in which the stator and rotor are facing coaxial plates. The rotation of the rotor is affected by the magnetic field generated by the current flowing through the stator windings and interacting with the magnetic field generated by the magnets carried by the rotor.

[0005] Conventional stator assemblies may be manufactured with a stator core formed of thin ferrous magnetic disks that are stacked and laminated together into a cylinder. Each disk has a number of openings that, when aligned with the openings of adjacent disks, form stator slots that extend axially through the length of the stator core. Conductive elements, such as metal rods, bars, windings, etc., are fed through these stator slots and secured to the stator core. A single stator slot may house a number of individual conductors that are arranged adjacent to each other in a radial direction relative to the stator core in a manner that forms concentric rings of conductors. For radial flux ACPM motors, the rotor may be surrounded by a stator, wherein the stator assembly is separated from the rotor assembly by an air gap. Separating the radially innermost ends of the stator slots are stator teeth that protrude toward the outer diameter (OD) periphery of the rotor assembly. The stator teeth cause the magnetic flux generated by the stator windings to be transferred directly across the air gap to the rotor and electromagnetically couple with the magnets located in the slots of the rotor core before completing the magnetic flux path back to the stator assembly.

[0006] This article proposes a motor having a mixture of bar and wire conductors for generating an electromotive force, a method for manufacturing such a motor, and a method for operating such a motor, as well as a motor vehicle equipped with such a motor. As an example, the efficiency and maximum torque output of the motor may be inhibited by excessive AC winding losses caused by the ohmic resistance of the electromagnetic winding to the current. Winding losses, also anachronistically referred to as "copper losses" (regardless of the conductor material), can cause electrical energy to be undesirably dissipated as heat, especially during high-speed motor operation. The motor may suffer additional losses due to the winding proximity effect, which causes the conductor closest to the air gap package to suffer uneven current distribution, accompanied by an increase in effective resistance at high operating speeds. In order to mitigate winding losses and effects, the disclosed motor adopts a design arrangement structure of different types of conductors, including the following mode: wherein solid wire or multi-strand wire conductors are encapsulated in the (innermost) slot layer closest to the rotor-stator air gap, and bar or hairpin conductors are placed in the (outermost) slot layer farthest from the air gap. Each line conductor may have a circular (first) cross-section with a reduced (first) area, while each strip conductor may have a rectangular (second) cross-section with an enlarged (second) area that is at least 5X-6X larger than the cross-sectional area of ​​the line. Furthermore, the ratio of line conductors to strip conductors in a given slot may be at least 3:1. These hybrid strip-line conductor arrangements help minimize AC winding losses at high speed operation, while maintaining a high slot fill factor and reduced DC copper losses at low operating speeds.

[0007] Various aspects of the present disclosure relate to design combinations of linear and strip conductors for electric machines such as motors, generators, transformers, inductors, dynamometers, converters, and the like. For example, the electric machine includes a protective outer casing, a stator assembly fixedly attached to the casing, and a rotor assembly rotatable relative to the stator assembly and separated from the stator assembly across an air gap. A set of magnets, such as permanent magnet (PM) blocks, are mounted to the rotor assembly (or stator assembly), and multiple sets of electromagnetic conductors are fed through slots in the stator assembly (or rotor assembly). Each set of electromagnetic conductors includes: a group of linear conductors, which are positioned adjacent to the air gap; and a group of strip conductors, which are radially spaced from the air gap and positioned adjacent to the linear conductors. Each strip conductor has a cross-sectional area that is significantly larger than the cross-sectional area of ​​each linear conductor.

[0008] Additional aspects of the present disclosure relate to an electric drive vehicle having a multi-phase brushless ACPM traction motor including both bar-type conductors and linear conductors. As used herein, the terms "vehicle" and "motor vehicle" are used interchangeably and synonymously to refer to any relevant vehicle platform, such as passenger cars (ICE, HEV, FEV, fuel cell, fully and partially autonomous passenger cars, etc.), commercial vehicles, industrial vehicles, tracked vehicles, off-road and all-terrain vehicles, motorcycles, agricultural equipment, watercraft, aircraft, electric bicycles, etc. In one example, the motor vehicle includes a body with a passenger compartment, a plurality of wheels mounted to the body (e.g., via corner modules coupled to an integral or non-load-bearing body chassis), and other standard original equipment. For electric drive vehicle applications, the vehicle is equipped with an electrified powertrain that employs one or more traction motor / generator units (MGUs) that operate alone (e.g., for FEV powertrains) or in combination with an internal combustion engine assembly (e.g., for HEV powertrains) to selectively drive one or more of the wheels to thereby propel the vehicle.

[0009] Continuing with the previous discussion, the traction motor includes a protective and insulating motor housing, a stator assembly having a stator core fixedly mounted within the motor housing, and a rotor assembly having a rotor core rotatably mounted within the motor housing. The stator core includes a series of circumferentially spaced and radially elongated stator slots. In contrast, the rotor assembly is nested within the stator assembly so that the rotor core is concentric with the stator core and is spaced from the stator core across an air gap. A set of circumferentially spaced magnets are mounted on or in the rotor core. Multiple groups of electromagnetic conductors are mounted to the stator core, with each group extending through a corresponding one of the stator slots. Each group of electromagnetic conductors includes: a group of linear conductors positioned adjacent to the air gap; and a group of bar conductors radially spaced from the air gap and positioned adjacent to the linear conductors. Each linear conductor has a line-specific (first) cross-sectional area and a line-specific (first) cross-sectional geometry, and each bar conductor has a bar-specific (second) cross-sectional area that is larger than the cross-sectional area of ​​the line, and a bar-specific (second) cross-sectional geometry that is different from the cross-sectional geometry of the line.

[0010] Aspects of the present disclosure also relate to manufacturing workflow processes, computer-readable media, and control logic for manufacturing or using any disclosed motor, motor drive system, and / or motor vehicle. In one example, a method for assembling a motor is presented. The representative method includes, in any order and in any combination with any of the options and features disclosed above and below: receiving a housing of the motor; attaching a stator to the housing; attaching a rotor to the housing so that the rotor can move relative to the stator and is separated from the stator across an air gap; attaching a plurality of magnets to one of the rotor or the stator; and attaching a plurality of electromagnetic conductors to the other of the rotor or the stator, the electromagnetic conductors including a plurality of linear conductors and a plurality of strip conductors, the linear conductors being positioned adjacent to the air gap and having a first cross-sectional area, and the strip conductors being positioned adjacent to the linear conductors, being radially spaced from the air gap, and having a second cross-sectional area greater than the first cross-sectional area.

[0011] For any of the disclosed vehicles, methods, and electric machines, each linear conductor may have a wire-specific (first) cross-sectional geometry, and each bar conductor may have a rod-specific (second) cross-sectional geometry that is different from the cross-sectional geometry of the wire. For example, the cross-sectional geometry of the wire may be a simple closed curve (e.g., a circle, an ellipse, a disk-shaped rectangle, etc.), while the cross-sectional geometry of the bar may be a rectilinear polygon (e.g., a rectangle with sharp or rounded corners, a square, etc.). As another option, the ratio of linear conductors to bar conductors may be at least about 3:1 (e.g., each stator slot may contain twelve linear conductors and four bar conductors). It may be desirable for the cross-sectional area of ​​each bar to be at least four times larger than the cross-sectional area of ​​each wire, or alternatively, at least five times larger, or in some preferred designs, about 6.5 times larger. For at least some applications, the linear conductors do not adhere, wrap, or wrap around each other. Alternatively, each linear and strip conductor may be enclosed in a respective sheath, a group of linear conductors may be pre-packaged in a housing, and / or each group of electromagnetic conductors may be embedded in a non-magnetic filler material.

[0012] For any of the disclosed vehicles, methods, and electric machines, the bar conductors in a given slot may be grouped into a single linear row and radially spaced from one another. In this case, the linear conductors in the same slot may be grouped into two or more linear rows and radially and circumferentially spaced from one another. As described above, the rotor assembly may include a rotor core that carries magnets, and the stator assembly may include a stator core that carries conductors and is surrounded by the rotor core and coaxial with the rotor core. The radially elongated stator slots extending through the stator core each contain a corresponding set of electromagnetic conductors, wherein the linear conductors are located at the radially inner ends of the stator slots and the bar conductors are located at the radially outer ends of the stator slots. It may be desirable that the slot filling factor of the electromagnetic conductor group in a given stator slot is at least about 0.4. As another option, the linear conductors may extend across approximately 30% to approximately 60% of the radial length of the stator slots.

[0013] For any of the disclosed vehicles, methods, and electric machines, an electric-specific (first) power inverter module (PIM) may be electrically coupled to a linear conductor (rather than a bar conductor) and may be operable to control current feed to the linear conductor (rather than a bar conductor), while a bar-specific (second) PIM may be electrically coupled to a bar conductor (rather than a linear conductor) and may be operable to control current feed to the bar conductor (rather than a linear conductor). Alternatively, a set of relay switches and a shared power inverter module may be electrically coupled to both the linear conductor and the bar conductor, and may be operable to control current feed to both the linear conductor and the bar conductor. As another option, each linear conductor may take on a different form factor, including a conductive solid wire or a multi-strand wire construction (e.g., an extruded single-piece wire or a stranded Litz wire). Similarly, each bar conductor may take on a different form factor, including a hairpin, I-pin, D-pin, and flat bar construction.

[0014] The present invention also includes the following technical solutions:

[0015] Solution 1. A motor, comprising:

[0016] case;

[0017] a stator attached to the housing;

[0018] a rotor movable relative to the stator and spaced apart from the stator across an air gap;

[0019] a plurality of magnets attached to one of the rotor or the stator; and

[0020] a plurality of electromagnetic conductors attached to the other of the rotor or the stator, the electromagnetic conductors comprising: a plurality of linear conductors positioned adjacent to the air gap and each having a first cross-sectional area; and a plurality of strip conductors radially spaced from the air gap, positioned adjacent to the linear conductors, and each having a second cross-sectional area greater than the first cross-sectional area.

[0021] Option 2. The electric machine according to Option 1, wherein each of the linear conductors has a first cross-sectional geometry, and each of the bar-type conductors has a second cross-sectional geometry different from the first cross-sectional geometry.

[0022] Option 3. An electric machine according to Option 2, wherein the first cross-sectional geometry is a simple closed curve and the second cross-sectional geometry is a straight polygon.

[0023] Option 4. The electric machine according to Option 1, wherein the ratio of the linear conductor to the strip conductor is at least about 3:1.

[0024] Option 5. An electric machine according to Option 1, wherein the second cross-sectional area is at least five times larger than the first cross-sectional area.

[0025] Embodiment 6. The electric machine according to embodiment 1, wherein the bar-type conductors are grouped into a single linear row and radially spaced apart from each other, and wherein the line-type conductors are grouped into a plurality of linear rows and spaced apart from each other.

[0026] Option 7. An electric motor according to Option 1, wherein the rotor includes a rotor core carrying the magnet, and the stator includes a stator core coaxial with the rotor core and surrounding the rotor core, the stator core defines radially elongated stator slots, the stator slots contain the electromagnetic conductors, wherein the linear conductors are located at the radial inner ends of the stator slots, and the bar conductors are located at the radial outer ends of the stator slots.

[0027] Embodiment 8. The electric machine according to embodiment 7, wherein a slot filling factor of the electromagnetic conductor and the stator slot is at least about 0.4.

[0028] Embodiment 9. The electric machine according to embodiment 7, wherein the linear conductor extends across approximately 30% to approximately 60% of the radial length of the stator slot.

[0029] Option 10. The electric motor according to Option 1 also includes: a first power inverter module (PIM), which is electrically coupled to the linear conductor instead of the strip conductor, and is configured to control the current feeding to the linear conductor instead of the strip conductor; and a second PIM, which is electrically coupled to the strip conductor instead of the linear conductor, and is configured to control the current feeding to the strip conductor instead of the linear conductor.

[0030] Option 11. The electric machine according to Option 1 also includes a plurality of relay switches and a shared power inverter module (PIM), both of which are electrically coupled to both the linear conductor and the strip conductor, and are configured to control current feeding to both the linear conductor and the strip conductor.

[0031] Embodiment 12. The electric machine according to embodiment 1, wherein the linear conductor comprises a solid linear conductor and / or a stranded linear conductor, and the strip conductor comprises an I-pin conductor, a D-pin conductor, a flat strip conductor and / or a hairpin conductor.

[0032] Solution 13. A motor vehicle, comprising:

[0033] Car body;

[0034] a plurality of wheels attached to the vehicle body; and

[0035] a traction motor attached to the body and operable to drive one or more of the wheels to thereby propel the motor vehicle, the traction motor comprising:

[0036] Motor housing;

[0037] a stator assembly having a stator core fixedly mounted within the motor housing, the stator core defining a plurality of circumferentially spaced and radially elongated stator slots;

[0038] a rotor assembly having a rotor core rotatably mounted within the motor housing, the rotor core being concentric with the stator core and spaced apart from the stator core across an air gap;

[0039] a plurality of magnets mounted to the rotor core; and

[0040] a plurality of sets of electromagnetic conductors mounted to the stator core and each extending through a respective one of the stator slots, the plurality of sets of electromagnetic conductors each including a set of linear conductors positioned adjacent the air gap and a set of bar conductors radially spaced from the air gap and positioned adjacent the linear conductors, the linear conductors each having a first cross-sectional area and a first cross-sectional geometry, and the bar conductors each having a second cross-sectional area greater than the first cross-sectional area and a second cross-sectional geometry different from the first cross-sectional geometry.

[0041] Solution 14. A method for assembling an electric motor, the method comprising:

[0042] a housing for receiving the motor;

[0043] attaching a stator to the housing;

[0044] attaching a rotor to the housing such that the rotor is movable relative to the stator and is spaced from the stator across an air gap;

[0045] attaching a plurality of magnets to one of the rotor or the stator; and

[0046] A plurality of electromagnetic conductors are attached to the other of the rotor or the stator, the electromagnetic conductors including a plurality of linear conductors positioned adjacent to the air gap and having a first cross-sectional area and a plurality of strip conductors positioned adjacent to the linear conductors, radially spaced from the air gap, and having a second cross-sectional area greater than the first cross-sectional area.

[0047] Option 15. The method according to Option 14, wherein the linear conductor has a first cross-sectional geometry, and the strip conductor has a second cross-sectional geometry different from the first cross-sectional geometry.

[0048] Option 16. The method according to Option 14, wherein the ratio of the linear conductor to the strip conductor is at least approximately 3:1.

[0049] Option 17. A method according to Option 14, wherein the second cross-sectional area is at least five times larger than the first cross-sectional area.

[0050] Option 18. The method of Option 14, wherein the strip-type conductors are grouped into a single linear row and radially spaced apart from one another, and wherein the line-type conductors are grouped into a plurality of linear rows and spaced apart from one another.

[0051] Option 19. A method according to Option 14, wherein the rotor includes a rotor core carrying the magnet, and the stator includes a stator core coaxial with the rotor core and surrounding the rotor core, the stator core defines radially elongated stator slots, the stator slots contain the electromagnetic conductors, wherein the linear conductors are located at the radial inner ends of the stator slots, and the bar conductors are located at the radial outer ends of the stator slots.

[0052] Embodiment 20. The method of embodiment 19, wherein the slot filling factor of the electromagnetic conductor and the stator slot is at least about 0.4, and wherein the linear conductor extends across about 30% to about 60% of the radial length of the stator slot.

[0053] The above summary of the invention does not represent every embodiment or every aspect of the present disclosure. On the contrary, the foregoing overview only provides a summary of some novel concepts and features set forth herein. When combined with the accompanying drawings and the appended claims, the above-mentioned features and advantages of the present disclosure and other features and accompanying advantages will be apparent through the following specific embodiments of the illustrated examples and representative modes for implementing the present disclosure. In addition, the present disclosure explicitly includes any and all combinations and sub-combinations of the elements and features presented above and below. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 is a schematic diagram of a representative electrically-driven motor vehicle having an electrified powertrain employing an alternating current permanent magnet (ACPM) traction motor with which aspects of the present disclosure may be practiced.

[0055] Figure 2 is an end view of a representative interior permanent magnet (IPM) electric machine employing a stator carrying conductors and a rotor carrying magnets, with which aspects of the present disclosure may be practiced.

[0056] Figure 3 is an enlarged view of a portion of a representative rotor assembly and a representative stator assembly according to aspects of the present disclosure, which has a design combination of both linear conductors and bar conductors for use, for example, in Figure 1 MGU or Figure 2 The ACPM motor provides reduced proximity effect and AC winding losses.

[0057] Figure 4 is a schematic single-line diagram illustrating a representative motor drive system in a hybrid bar-wire motor according to various aspects of the present disclosure, the motor drive system having a dedicated PIM for controlling the flow of electrical power to a group of line-type conductors and a dedicated PIM for controlling the flow of electrical power to a group of bar-type conductors.

[0058] Figure 5 is a schematic single-line diagram illustrating a representative motor drive system in a hybrid bar-wire motor according to various aspects of the present disclosure, the motor drive system having a set of relay switches and a shared power inverter module for controlling the flow of electrical power to a group of line conductors and a group of bar conductors.

[0059] The present disclosure is susceptible to various modifications and alternative forms, and some representative embodiments of the present disclosure are shown in the drawings by way of example and will be described in detail herein. However, it should be understood that the novel aspects of the present disclosure are not limited to the specific forms shown in the drawings listed above. On the contrary, the present disclosure covers all modifications, equivalents, combinations, permutations, groupings and alternatives that fall within the scope of the present disclosure, such as those covered by the appended claims. DETAILED DESCRIPTION

[0060] The present disclosure allows for embodiments in many different forms. Representative embodiments of the present disclosure are shown in the accompanying drawings and will be described in detail herein with the understanding that these embodiments are provided as illustrations of the disclosed principles rather than limitations on the broad aspects of the present disclosure. To this extent, elements and limitations described in the "Abstract," "Technical Field," "Background Technology," "Content of the Invention," "Description of the Drawings," and "Specific Implementation Methods" sections but not explicitly set forth in the claims should not be incorporated into the claims individually or collectively by implication, inference, or otherwise. In addition, the expressions "first," "second," "third," etc. in the specification or claims are not themselves used to establish order or numerical limitations; unless otherwise specifically stated, these names can be used to facilitate reference to similar features in the specification and drawings and to divide between similar elements in the claims.

[0061] For purposes of this Detailed Description, unless otherwise stated: the singular includes the plural and vice versa; the terms "and" and "or" shall be both conjunctions and disjunctive conjunctions; the terms "any" and "all" shall both mean "any and all"; and the terms "including," "comprising," "containing," "having," and the like shall each mean "including but not limited to." In addition, approximate terms such as "approximately," "almost," "substantially," "roughly," "approximately," and the like may each be used herein to mean, for example, "at, approximately, or nearly at," or "within 0-5% of," or "within an acceptable manufacturing tolerance," or any logical combination of the foregoing. Finally, directional adjectives and adverbs such as head, tail, inboard, outboard, starboard, port, vertical, horizontal, up, down, front, rear, left, right, and the like may be relative to a motor vehicle, such as relative to a forward direction of travel of a motor vehicle when the vehicle is operatively oriented on a level running surface.

[0062] Referring now to the drawings, wherein like reference numerals represent like features throughout the several views, Figure 1, a schematic diagram of a representative motor vehicle is shown, which is generally designated 10 and is depicted herein for discussion purposes as an electrically driven passenger car having a parallel dual clutch (P2) hybrid electric powertrain. The illustrated automobile 10, also referred to herein as a "motor vehicle" or simply "vehicle," is merely an exemplary application with which various aspects of the present disclosure may be practiced. Likewise, incorporating the inventive concepts into a hybrid electric powertrain should also be understood as a representative implementation of the inventive concepts disclosed herein. As such, it should be understood that the novel aspects of the present disclosure may be applied to other powertrain architectures, may be incorporated into any logically related type of motor vehicle, and may be equally useful in both automotive and non-automotive applications. Finally, only selected components of the motor vehicle, motor drive system, and motor are shown and will be described in additional detail below. Nevertheless, the vehicles, systems, and motors discussed herein may include many additional and alternative features, as well as other available peripheral components for performing the various methods and functions of the present disclosure.

[0063] Figure 1 The electrified vehicle powertrain of is shown having a prime mover, represented herein by a restartable internal combustion engine (ICE) assembly 12 and an electric motor / generator unit (MGU) 14, drivingly connected to a drive shaft 15 of a final drive system 11 through a multi-speed automatic power transmission 16. The engine 12 transmits power to the input side of the transmission 16 by means of torque, typically via an engine crankshaft 13. The engine torque is first transmitted via the crankshaft 13 to rotate an engine-driven torsional damper assembly 26; the engine torque is simultaneously transmitted to an engine disconnect device 28 through the torsional damper assembly 26. The engine disconnect device 28, when operatively engaged, transmits torque received from the ICE assembly 12 to a torque converter (TC) assembly 18 by means of the damper 26. As the name implies, the engine disconnect device 28 can be selectively disengaged to drivingly disconnect the ICE 12 from the motor 14, the TC assembly 18, and the transmission 16.

[0064] To promote Figure 1 In the hybrid vehicle 10, the multi-speed power transmission 16 is adapted to receive, selectively manipulate and distribute the traction power output from the engine 12 and the motor 14 to the vehicle's final drive system 11. The final drive system 11 is represented herein by a drive shaft 15, a rear differential 22 and a pair of rear drive wheels 20. Figure 1 The power transmission 16 and torque converter 18 may share a common transmission oil pan or "sump" 32 for supplying hydraulic fluid. A shared transmission pump 34 provides sufficient hydraulic pressure for the fluid to selectively actuate the hydraulically activated elements of the transmission 16, the TC assembly 18, and the engine disconnect device 28 for some embodiments.

[0065] The ICE assembly 12 operates to propel the vehicle 10 independently of the traction electric motor 14, such as in an "engine only" operating mode, or in cooperation with the motor 14, such as in a "vehicle launch" or "motor boost" operating mode. Figure 1 In the example depicted in , ICE assembly 12 may be any available or future developed engine, such as a compression ignited diesel engine or a spark ignited gasoline or flex-fuel engine, that is readily adapted to provide its available power output generally at a certain number of revolutions per minute (RPM). Figure 1 Although not explicitly depicted in the drawings, it should be appreciated that the final drive system 11 may employ any available configuration, including a front-wheel drive (FWD) layout, a rear-wheel drive (RWD) layout, a four-wheel drive (4WD) layout, an all-wheel drive (AWD) layout, a six-by-four (6X4) layout, etc.

[0066] Figure 1 Also depicted is an electric motor / generator unit ("motor") 14 operatively connected to a torque converter 18 via a rotor shaft, motor support hub or belt (collectively referred to as a motor output member 29). The torque converter 18, in turn, drivingly connects the motor 14 to an input shaft 17 of a transmission 16. The electric motor / generator unit 14 is comprised of an annular stator assembly 21 that surrounds and is concentric with a cylindrical rotor assembly 23. Electrical power is provided to the stator 21 via a high voltage (HV) electrical system that includes electrical rails / cables 27 that pass through the motor housing via suitable sealed and insulated feed-throughs (not shown). Conversely, electrical power may be provided from the MGU 14 to an onboard traction battery pack 30, for example during a regenerative braking mode. The operation of any of the powertrain components shown may be governed by an onboard or remote vehicle controller or module, or a network of controllers / modules / devices, all variations of which are described herein. Figure 1 It is represented by a programmable electronic control unit (ECU) 25.

[0067] The power transmission 16 may use a differential gear arrangement 24 to achieve selectively variable torque and speed ratios between the transmission input shaft 17 and the output shaft 19, respectively. One form of differential gear arrangement is an epicyclic planetary gear arrangement that provides the advantages of compactness and different torque and speed ratios between the components of the planetary gear arrangement. Conventionally, hydraulically actuated torque-building devices, such as clutches and brakes, are selectively engaged to activate the aforementioned gear elements to establish the desired forward and reverse speed ratios between the input and output shafts 17, 19 of the transmission. Although contemplated as a 6-speed or 8-speed automatic transmission, the power transmission 16 may optionally employ other functionally appropriate configurations, including a continuously variable transmission (CVT) architecture, a manual or automated-manual transmission, and the like.

[0068] The torque converter assembly 18 operates as a fluid coupling for operatively connecting the engine 12 and the motor 14 with the internal epicyclic gearing 24 of the power transmission 16. Disposed within the internal fluid chamber of the torque converter assembly 18 is a bladed impeller 36 facing a bladed turbine 38. The impeller 36 is juxtaposed with the turbine 38 in serial power flow fluid communication, wherein a TC stator (not shown) is disposed between the impeller 36 and the turbine 38 to selectively change the fluid flow therebetween. Torque transfer from the engine and motor output members 13, 29 to the transmission 16 via the TC assembly 18 can be achieved by stirring excitation of a hydraulic fluid such as transmission oil within the internal fluid chamber of the TC caused by the rotation of the blades of the impeller and turbine 36, 38. To protect these components, the torque converter assembly 18 is constructed with a TC pump housing, which is primarily defined by a transmission side pump housing 40, which is fixedly attached to an engine side pump cover 42 so that a working hydraulic fluid chamber is formed therebetween.

[0069] Figure 2 An example of an electric machine 114 is shown that employs a permanent state magnetic material that exchanges electromagnetic forces with conductive windings to convert electrical energy into mechanical energy and vice versa. The electric machine 114 has a multi-phase, conductor-wound stator assembly 116 nested therein and surrounding a synchronous reluctance rotor assembly 118 that carries magnets. Although it can be used in both automotive and non-automotive applications, Figure 2 The electric machine 114 may be particularly suitable for use in a hybrid electric powertrain as a traction motor (eg, a traction motor) used with an engine (eg, an ICE assembly 12). Figure 1 The motor 114 is a motor 114 that is configured to operate in at least an engine starting mode, a regenerative charging mode, and a torque assist mode. The motor 114 may be designed to achieve: relatively high efficiency (e.g., at least 85% efficiency over a calibrated output power and speed range); relatively high power density (e.g., greater than 1500 watts per liter) and torque density (e.g., greater than 5 Newton-meters per liter); a relatively large peak power range (e.g., 4 to 6 kilowatts or greater); a high top speed (e.g., at least 18,000 rpm); reduced mass and inertia (e.g., for rapid dynamic response to user output demands); and fit into a relatively small packaging space. The motor 114 may employ numerous alternative architectures to meet similar and alternative operating parameters.

[0070] Continue to refer Figure 2, the stator assembly 116 is coaxial with and surrounds the rotor assembly 118 while maintaining a small air gap 115 therebetween. According to the illustrated example, the air gap 115 may be, for example, about 0.2 millimeters (mm) to about 1.2 mm in order to maximize power output and minimize the number of permanent magnets 120 carried by the rotor assembly 118 to provide the desired power output. Figure 2 Representative stator and rotor assemblies 116, 118 are concentrically aligned about a common longitudinal center axis A of the electric machine 114. The stator assembly 116 has an annular stator core 126 having a central bore 122 in which the rotor assembly 118 is nested. For example, the rotor assembly 118 has a cylindrical rotor core 128 that is keyed, splined, welded, etc. to an output shaft (e.g., Figure 1 motor output member 29). It should be appreciated that a protective and insulating outer housing (e.g., Figure 1 The motor housing 31 in the embodiment may surround the outer periphery of the stator assembly 116 and may be capable of rotatably supporting the rotor and rotor output shaft of the motor 114 .

[0071] Figure 2 The rotor assembly 118 is manufactured with a rotor core 128, which may have a right cylindrical geometry having an annular shape for supporting a plurality of permanent magnets 120 (twenty-four (24) PMs in the illustrated example) circumferentially spaced about a central bore 124. Specifically, the rotor core 128 may be stamped, precision machined, and assembled with a plurality of rotor slots 130 arranged in radially spaced barrier layers (e.g., four different barrier layers). A first barrier layer 130A of the slots 130 may be positioned closest to the inner periphery of the rotor core 128, while a fourth barrier layer 130D of the slots 130 may be positioned farthest from the inner periphery of the rotor body compared to the other barrier layers. A second barrier layer 130B may be radially disposed between the first and third barrier layers 130A, 130C, while the third barrier layer 130C may be radially disposed between the second and fourth barrier layers 130B, 130D. For at least some embodiments, only selected barriers (e.g., first and third barriers 130A, 130C) may house magnets 120, while other selected barriers (e.g., second and fourth barriers 130B, 130D) do not house magnets 120 and thus act as flux barriers. In other embodiments, only one barrier or all barrier layers may include slots in which permanent magnets are stored. The rotor core 128 may be made of metal disc-shaped laminates including high-grade steel billets that are stacked and adhered together to maintain high-speed rotational stresses within predetermined limits.

[0072] Figure 2The stator assembly 116 is manufactured with a stator core 126, which may also have a right cylindrical geometry having a generally annular shape, and may have a plurality of circumferentially spaced, radially elongated stator slots 132 (e.g., a total of 60 slots in the illustrated example). Each stator slot 132 extends axially through the stator core 126 parallel to the rotation axis A of the motor 114. These stator slots 132 house conductive multi-phase electromagnetic stator windings 134. The stator windings 134, also referred to herein as "wire windings" or "bar windings," may be grouped into different groups, each of which may carry the same number of current phases, such as three, five, six, or seven phases. In addition, the stator windings 134 may extend axially beyond the open longitudinal ends of the stator core 126. The ratio of the outer diameter of the stator core 126 to the axial length of the stator core 126 may be not less than 1.5 and not greater than 3.5, for example, to meet the packaging space constraints of the desired application of the motor 114, such as Figure 1 vehicle powertrain.

[0073] For ease of manufacturing and simplicity of design, it may be desirable for all permanent magnets 120 to share the same rectangular polyhedral shape. However, any one or more or all of the PM bodies may take on countless shapes and sizes, including other polyhedral block magnets, annular (ring-shaped) magnets, bread loaf magnets, curved tile magnets, etc. In a non-limiting example, each permanent magnet 120 may have a thickness of approximately 1.5 mm to 2.5 mm to fit within a slot 130 of complementary dimensions. The total mass of the magnet material used by the motor 114 (i.e., the mass of all magnets 120) may be approximately 150 grams to approximately 250 grams. The permanent magnets 120 of the motor 114 may all be made of the same material, such as neodymium iron boron (NdFeB); alternatively, the magnets 120 may be made of different materials, such as samarium cobalt (SmCo), aluminum nickel cobalt (AlNiCo), or any combination of rare earth magnet materials.

[0074] Unlike permanent magnets 120, it may be desirable Figure 2 The multi-phase stator winding 134 is composed of a mixture of electromagnetic conductors of different shapes and sizes. Figure 3As described extensively in the discussion of , the stator windings 134 may include both bar-type conductors (e.g., U-shaped hairpin windings) and wire-type conductors (e.g., copper wire windings). The legs of the hairpin windings may be inserted into the slots 132 of the stator core 126, with each leg extending through a different stator slot 132 so that the hairpin crown (or "end-turn") extends over several stator slots 132 (e.g., each crown may extend across three or more slots). These hairpin windings 134 may be inserted in a "staggered" or "staggered" pattern relative to adjacent hairpins. Any given stator slot 132 may contain several hairpin legs (e.g., four to eight) and several discrete wire winding segments (e.g., 8 to 24). Once all of the electromagnetic windings 134 are inserted into the slots 132 of the stator core 126, the ends of the windings protruding from the longitudinal ends of the stator core 126 may be bent. Each winding 134 is then electrically connected.

[0075] During operation of the electric machine 114, for example, in a regenerative charging mode, the rotor assembly 118 rotates via the rotor output shaft while the stator assembly 116 remains relatively stationary. In this case, the permanent magnets 120 move through the multi-phase stator windings 134; the magnetic field emitted by the permanent magnets 120 generates current in the windings 134 through electromagnetic induction. The induced current can be used to supply power to a load (e.g., Figure 1 The electric motor 114 is powered by a rechargeable traction battery pack 30. In contrast, during operation of the electric motor 114, for example, in an engine starting mode, an EV drive mode, or a torque assist mode, current is supplied to the stator windings 134 by a suitable power source (e.g., the traction battery pack 30). Passing the supplied current through the multi-phase stator windings 134 will generate a magnetic field at the radially inward ends of the stator teeth 136. The magnetic field output from these stator teeth 136 interacts with the permanent magnets 120 in the rotor assembly 118, causing the rotor core 128 and the attached shaft to rotate in unison to generate a rotational drive force.

[0076] PM traction motors may suffer from high copper losses and high AC winding (proximity / skin) effects when operating at high speeds, which may result in high motor operating temperatures and reduced torque output. The electromagnetic conductors closest to the rotor-stator air gap are more affected by winding losses and effects during high motor speeds. To mitigate such AC winding losses and effects, solid wire or stranded wire conductors with reduced cross-section are placed in the slot layers closest to the air gap. Hairpins, I-pins, or other strip conductors with larger cross-sections are placed at the slot layers farthest from the air gap to increase the slot fill factor and reduce DC winding losses. For at least certain operating points of high motor speeds and torques (e.g., 9000+RPM, 400+Nm), this design combination of wire and strip conductors provides a significant improvement in motor efficiency (e.g., about 30%); even higher efficiency improvements (e.g., about 50%) can be achieved at higher speeds (e.g., 18,000+RPM).

[0077] Next turn Figure 3 , which shows an example of an electric machine 214 that uses a hybrid bar-wire conductor arrangement structure to reduce AC winding losses at high speed operation and reduce DC copper losses at low operating speeds. Although different in appearance, it is envisioned that the above reference Figure 1 The traction motor / generator unit 14 and Figure 2 Any of the features and options described for the multi-phase ACPM motor 114 may be incorporated into the Figure 3 As a non-limiting overlap, the motor 214 includes a stator assembly 216 carrying conductors coaxially aligned with a rotor assembly 218 carrying magnets and separated by an air gap 215. Similar to Figure 2 The stator assembly 116, Figure 3 The stator assembly 216 is constructed with a magnetic flux permeable annular stator core 226 having a plurality of circumferentially spaced stator slots 232 radially aligned with the core 226 and extending axially through the core 226. Similar to Figure 2 The rotor assembly 118, Figure 3 The rotor assembly 218 is constructed with a stacked, laminated cylindrical rotor core 228 having a series of circumferentially spaced permanent magnets mounted thereon or therein.

[0078] A respective set of electromagnetic conductors 234 is wound through each axially elongated slot 232 of the stator core 226, wherein each set contains a mixture of both wire-type conductors 234A and strip-type conductors 234B. According to the illustrated example, each conductor set 234 includes a subset of wire-type conductors 234A that are grouped into a different (first) group; the wire group is positioned adjacent to the air gap 215 and isolated to the proximal section of the slot 232 closest to the air gap 215. Each conductor set 234 also includes a subset of strip-type conductors 234B that are grouped into a different (second) group; the strip group is positioned adjacent to the wire-type conductors 234A, radially spaced from the air gap 215, and isolated to the distal section of the slot 232 farthest from the air gap 215. The wire-type conductors 234A can take a variety of different form factors, including a conductive solid wire construction (e.g., an extruded single-piece copper wire) or a stranded wire construction (e.g., individually insulated copper strands "Litz" wire). Likewise, the strip conductor 234B may take on a variety of different form factors, including hairpin, I-pin, D-pin, and flat bar configurations (e.g., each precision formed into a single-piece configuration from copper, steel, aluminum, etc.). Although illustrated as having two different sized / shaped conductors, it is contemplated that the motor 214 may include three or more different sized / shaped conductors.

[0079] To optimize packaging space and motor operation, the linear conductors 234A may be grouped into a plurality of linear rows (e.g., arranged in a rectangular array of mutually parallel rows and mutually parallel columns) and may be spaced apart from one another within the slots 232 (e.g., radially and circumferentially spaced relative to the stator core 226), such as in Figure 3 234B) and are spaced apart from one another (e.g., radially apart relative to the stator core 226). It may be desirable to have a ratio of linear conductors 234A to bar conductors 234B of at least about 2:1, or for at least some configurations, at least about 3:1 (e.g., each stator slot 232 is shown as containing twelve linear conductors 234A and four bar conductors 234B). As shown, the linear conductors 234A are not adhered, wrapped, or wrapped around each other, or around the bar conductors 234B, and are therefore loosely fitted within the slots 232 (i.e., enclosed with sufficient clearance to allow free play). Alternatively, each linear conductor 234A may be encased in a respective insulating sheath, each group of linear conductors 234A may be pre-packaged in a shared enclosure, and / or each set of electromagnetic conductors 234 may be embedded in a non-magnetic filler material.

[0080] In order to minimize AC winding losses at high-speed motor operating points and to minimize DC copper losses at low-speed motor operating points, all of the line conductors 234A in a given group 234 may be located at the radially inner ends of the corresponding stator slots 232 of the group (i.e., in the lower / proximal half of the slot), and all of the bar conductors 234B in the group 234 may be located at the radially outer ends of the stator slots (i.e., in the upper / distal half of the slot). In addition, the line conductors 234A may extend across the radial slot length L of each stator slot 232. S1 20-65% of the stator slots 232, or in at least some embodiments, at least about 30%, but no more than about 60%. As shown, all twelve line conductors 234A are confined to and extend across the radially inner third of the stator slots 232, while all four bar conductors 234B are confined to and extend across the radially outer two-thirds of the stator slots 232.

[0081] For at least some applications, it may be desirable for each set of electromagnetic conductors 234 and their corresponding stator slots 232 to have a slot fill factor (SFF) of about 0.35-0.95, or in at least some preferred embodiments, at least about 0.4. As used herein, the term "slot fill factor" may be given its ordinary and customary meaning, such as the mathematical ratio of the sum of the cross-sectional areas of the conductive material of the conductors to the total cross-sectional area of ​​the slots. Figure 3 , the total cross-sectional area of ​​the copper material of each group of electromagnetic conductors 234 occupies approximately 67% (SFF≈0.67) of the cross-sectional area of ​​the slot 232 occupied by these conductors.

[0082] Continue to refer Figure 3 , each linear conductor 234A has a line-specific (first) cross-sectional area that is significantly smaller than the bar-specific (second) cross-sectional area of ​​each strip conductor 234B. For example, it may be desirable for the cross-sectional area of ​​each strip conductor to be at least four times larger than the cross-sectional area of ​​each line, or optionally at least five times larger. As shown, the cross-section of the strip conductor 234B has a total area that is approximately 6.6 times larger than the total area of ​​the cross-sectional area of ​​the linear conductor 234A. According to Figure 3In the design of the representative motor 214, the linear conductor 234A has a line-specific (first) cross-sectional geometry that is different from the bar-specific (second) cross-sectional geometry of the strip conductor 234B. For example, the cross-section of the linear conductor 234A may have a simple closed curve shape (e.g., circular, elliptical, discorectangular, etc.). In contrast, the cross-section of the strip conductor 234B may have a rectilinear polygonal shape (e.g., rectangular, square, etc. with sharp or rounded corners). It is contemplated that the linear conductor 234A and the strip conductor 234B may take on regular and irregular shapes and sizes that are alternative to those shown in the figures, and may share similar geometries without departing from the intended scope of the present disclosure.

[0083] To optimize e.g. Figure 3 The copper loss characteristics of the hybrid bar-line motor of the motor 214, the high voltage electrical system regulating the power transfer to and from the motor may employ multiple power inverters, at least one of which is dedicated to controlling the operation of the line conductors, and at least one of which is dedicated to controlling the operation of the bar conductors. For example, Figure 5 An example of a motor drive system 300 is illustrated, having an electric motor 314; a first power inverter module (PIM1) 350 electrically coupled to a subset of line conductors 334A carried by a stator within the motor 314; and a second PIM 352 electrically coupled to a subset of bar conductors 334B carried by a stator within the motor 314. In this example, the first PIM1 350 is selectively operable (e.g., via a communication connection to the first PIM1 350). Figure 1 The motor control module (MCM) of the ECU 25 of the embodiment of the present invention can be used to independently control the current feed to the linear conductor 334A (rather than the strip conductor 334B). In contrast, the second PIM2 352 can be selectively operated (e.g., via the MCM and ECU controller) to independently control the current feed to the strip conductor 334B (rather than the linear conductor 334A). For example, during operation of the electric motor 314, the linear conductor 334A located closest to the rotor-stator air gap is fed with electric power from the first PIM1 350 during high-speed operation, while the strip conductor 334B located farthest from the air gap functions at a lower speed via the electric power feed from the second PIM2 352.

[0084] As a bar-line motor for optimized mixing (e.g. Figure 3 As another alternative to the copper loss characteristics of the motor 214), the HV electrical system may employ electromechanical switches (e.g., relays) and / or electronic switches (e.g., insulated gate bipolar transistor (IGBT) semiconductor switches) that operate in conjunction with separate power inverters to independently and collectively control the operation of the strip conductors and line conductors. For example, Figure 5An example of a motor drive system 400 is illustrated, having an electric motor 414; a subset of stator-carried line conductors 434A and a subset of stator-carried bar conductors 434B within the motor 414; a shared power inverter module (PIM1) 450 electrically coupled to both the line conductors 434A and the bar conductors 434B; and electrical switches S1-S3 disposed between the line conductors 434A and the bar conductors 434B and selectively interconnecting the line conductors 434A and the bar conductors 434B to the shared PIM 450. During operation of the electric motor 414, the PIM 450 may transmit electrical power flow only to the line conductors 434A, only to the bar conductors 434B, or to both sets of conductors 434A, 434B in series.

[0085] A variety of new electromagnetic conductor arrangement structures for electric machines are discussed above, which help reduce copper losses, reduce winding effects and improve thermal operating characteristics. For example, solid wire or stranded conductors are located in the slot layer adjacent to the rotor-stator air gap, while hairpin or I-pin bar conductors are located in the slot layer farthest from the air gap in the radial direction. Placing small-gauge linear conductors close to the air gap helps reduce AC winding effects and winding losses at high operating speeds. In contrast, larger-gauge hairpin / bar conductors separated from the air gap help ensure a high slot filling factor, as well as reduced DC winding losses. In a non-limiting example, at least about 40% to about 60% of the available conductor slot area can be occupied by linear conductors, and the remaining 40% to 60% of the slot area can be occupied by bar conductors. The disclosed motor drive system can use a single inverter or multiple inverters to control the electrical power feed to / from the mixed conductor motor. For example, during high speed operation, the line conductors close to the air gap package may be fed from one inverter, while the larger bar conductors are only acted upon at lower speeds by another inverter.

[0086] Various aspects of the present disclosure have been described in detail with reference to the illustrated embodiments; however, those skilled in the art will recognize that many modifications may be made thereto without departing from the scope of the present disclosure. The present disclosure is not limited to the precise configurations and compositions disclosed herein; any and all modifications, changes and variations apparent from the foregoing description are within the scope of the present disclosure as defined by the appended claims. Moreover, the present concept expressly includes any and all combinations and sub-combinations of the foregoing elements and features.

Claims

1. A motor, comprising: case; a stator attached to the housing; a rotor movable relative to the stator and spaced apart from the stator across an air gap; a plurality of magnets attached to one of the rotor or the stator; as well as a plurality of electromagnetic conductors attached to the other of the rotor or the stator, the electromagnetic conductors comprising: a plurality of linear conductors positioned adjacent the air gap and each having a first cross-sectional area; and a plurality of strip conductors radially spaced from the air gap, positioned adjacent to the line conductor, and each having a second cross-sectional area greater than the first cross-sectional area.

2. The motor according to claim 1, wherein: Each of the line-type conductors has a first cross-sectional geometry, and each of the strip-type conductors has a second cross-sectional geometry that is different from the first cross-sectional geometry.

3. The motor according to claim 2, wherein: The first cross-sectional geometry is a simple closed curve and the second cross-sectional geometry is a rectilinear polygon.

4. The motor according to claim 1, wherein: The ratio of the linear conductor to the strip conductor is at least about 3:

1.

5. The motor according to claim 1, wherein: The second cross-sectional area is at least five times greater than the first cross-sectional area.

6. The motor according to claim 1, wherein: The strip-type conductors are grouped into a single linear row and radially spaced from one another, and wherein the line-type conductors are grouped into a plurality of linear rows and spaced from one another.

7. The motor according to claim 1, wherein: The rotor includes a rotor core carrying the magnets, and the stator includes a stator core coaxial with the rotor core and surrounding the rotor core, the stator core defining radially elongated stator slots, the stator slots containing the electromagnetic conductors, wherein the linear conductors are located at radially inner ends of the stator slots, and the bar conductors are located at radially outer ends of the stator slots.

8. The electric machine according to claim 7, wherein: The electromagnetic conductor and the stator slots have a slot filling factor of at least about 0.

4.

9. The motor according to claim 7, wherein: The linear conductor extends across about 30% to about 60% of the radial length of the stator slot.

10. The electric machine according to claim 1, further comprising: a first power inverter module (PIM) electrically coupled to the linear conductors instead of the strip conductors and configured to control current feeding to the linear conductors instead of the strip conductors; and a second PIM electrically coupled to the strip conductor instead of the line conductor and configured to control current feeding to the strip conductor instead of the line conductor.

Images