Surface / built-in permanent magnet rotor for electric machine

Abstract

A multi-phase, multi-pole surface / built-in permanent magnet motor / generator (S / IPM machine) is described and includes a rotor disposed on a rotor shaft within an annular stator and a plurality of internal and surface mounted permanent magnets disposed in longitudinal pockets of the rotor.

Description

Technical Field

[0001] The present invention relates to a surface / interior permanent magnet rotor for an electric machine. Background Art

[0002] Electric motor / generators, such as interior permanent magnet (IPM) motors, may be used as torque-producing devices on vehicles.

[0003] There is a need for electric machines with increased torque density, increased power density, increased power at high speeds, and other performance characteristics that minimize flux leakage, improve thermal management, fit within available packaging space, and / or reuse part or component designs to minimize engineering effort and design validation. Summary of the invention

[0004] A multi-phase, multi-pole surface / interior permanent magnet motor / generator (S / IPM motor) is described and includes a rotor disposed on a rotor shaft within an annular stator and a plurality of interior and surface mounted permanent magnets disposed in longitudinal pockets of the rotor.

[0005] One aspect of the present disclosure may include a rotor assembly for an electric machine, comprising a plurality of disc-shaped laminations; a rotor shaft; an enclosure; a plurality of internal permanent magnets; and a plurality of surface-mounted permanent magnets. The plurality of disc-shaped laminations are arranged on the rotor shaft in a stacked configuration and have a plurality of pole portions, the plurality of pole portions including a plurality of internal cavities and a plurality of surface-mounted cavities. The plurality of internal permanent magnets are disposed in the plurality of internal cavities, and the plurality of surface-mounted permanent magnets are disposed in the plurality of surface-mounted cavities. The enclosure encapsulates an outer surface defined by the plurality of disc-shaped laminations and the plurality of surface-mounted permanent magnets.

[0006] Another aspect of the present disclosure may include that each of the plurality of surface mounted permanent magnets has a cross-section modified to include an arc-shaped outward side.

[0007] Another aspect of the present disclosure may include that the plurality of surface mounted permanent magnets have a rectangular cross-section modified to include an arc-shaped outward side.

[0008] Another aspect of the present disclosure may include that each of the plurality of surface mounted permanent magnets has a trapezoidal cross-section modified to include an arc-shaped outer side.

[0009] Another aspect of the present disclosure may include that each of the plurality of surface mounted permanent magnets has a triangular cross-section modified to include an arc-shaped outward side.

[0010] Another aspect of the present disclosure may include that each of the plurality of surface mounted permanent magnets has an arcuate cross-section including an arcuate outwardly facing side.

[0011] Another aspect of the present disclosure may include an arcuate outboard side coextensive with an outer circumference of the rotor assembly.

[0012] Another aspect of the present disclosure may include the encapsulant being a carbon fiber fabric that encapsulates an outer surface defined by a plurality of disc-shaped laminations and a plurality of surface-mounted permanent magnets.

[0013] Another aspect of the present disclosure may include that the plurality of interior cavities defined for the plurality of pole segments are rectangular prisms arranged in a single V-shaped configuration.

[0014] Another aspect of the present disclosure may include that the plurality of interior cavities defined for the plurality of pole segments are rectangular prisms arranged in a double V-shaped configuration.

[0015] Another aspect of the present disclosure may include that the plurality of internal cavities defined for the plurality of pole segments are rectangular prisms arranged in a double V-shaped configuration without the presence of bridges in the disc-shaped laminations.

[0016] Another aspect of the present disclosure may include that the plurality of interior cavities defined for the plurality of pole segments are rectangular prisms arranged in a U-shaped configuration.

[0017] Another aspect of the present disclosure may include through holes formed in the axial passage between the rotor assembly and the surface mounted permanent magnets.

[0018] Another aspect of the present disclosure may include permanent magnets composed of rare earth materials.

[0019] Another aspect of the present disclosure may include an electric machine having a stator including a stator core and electrical windings arranged in a distributed winding configuration.

[0020] The present invention provides the following technical solutions:

[0021] 1. A rotor assembly for an electric motor, comprising:

[0022] a plurality of disc-shaped laminations; a rotor shaft; an encapsulation; a plurality of internal permanent magnets; and a plurality of surface mounted permanent magnets;

[0023] wherein a plurality of disc-shaped laminations are arranged on a rotor shaft in a stacked structure;

[0024] wherein the plurality of disc-shaped laminations include a plurality of magnetic pole portions,

[0025] wherein the plurality of pole sections include a plurality of internal cavities and a plurality of surface mount cavities;

[0026] wherein a plurality of internal permanent magnets are disposed in a plurality of internal cavities;

[0027] wherein a plurality of surface mounted permanent magnets are disposed within a plurality of surface mounted cavities; and

[0028] Therein, the enclosure encapsulates an outer surface defined by a plurality of disc-shaped laminations and a plurality of surface-mounted permanent magnets.

[0029] 2. A rotor assembly according to claim 1, wherein each of the plurality of surface-mounted permanent magnets includes a cross-section modified to include an arcuate outwardly facing shape.

[0030] 3. A rotor assembly according to claim 2, wherein each of the plurality of surface-mounted permanent magnets has a rectangular cross-section modified to include an arc-shaped outward side.

[0031] 4. A rotor assembly according to claim 2, wherein each of the plurality of surface-mounted permanent magnets has a trapezoidal cross-section modified to include an arc-shaped outward side.

[0032] 5. A rotor assembly according to claim 2, wherein each of the plurality of surface-mounted permanent magnets has a triangular cross-section modified to include an arc-shaped outward side.

[0033] 6. A rotor assembly according to claim 2, wherein each of the plurality of surface-mounted permanent magnets has an arcuate cross-section including an arc toward the outside.

[0034] 7. A rotor assembly according to Option 2, wherein the arc is coextensive with the outer circumference of the rotor assembly toward the outside.

[0035] 8. The rotor assembly of claim 1 , wherein the encapsulant comprises a carbon fiber fabric encapsulating an outer surface defined by the plurality of disk-shaped laminations and the plurality of surface-mounted permanent magnets.

[0036] 9. A rotor assembly according to Option 1, wherein the plurality of internal cavities defined for the plurality of magnetic pole portions comprise rectangular prisms arranged in a single V-shaped structure.

[0037] 10. The rotor assembly of claim 1, wherein the plurality of internal cavities defined for the plurality of magnetic pole portions comprise rectangular prisms arranged in a double V-shaped configuration.

[0038] 11. A rotor assembly according to claim 10, wherein the plurality of internal cavities defined for the plurality of pole portions comprise rectangular prisms arranged in a double V-shaped configuration and no bridges are present in the disc-shaped laminations.

[0039] 12. A rotor assembly according to claim 1, wherein the plurality of internal cavities defined for the plurality of magnetic pole portions comprise rectangular prisms arranged in a U-shaped structure.

[0040] 13. The rotor assembly of claim 1, wherein each of the plurality of surface mounted cavities comprises an axial channel, wherein a through hole is formed in the axial channel between the rotor assembly and the surface mounted permanent magnet.

[0041] 14. A multi-phase multi-pole permanent magnet motor (motor), comprising:

[0042] a rotor assembly disposed within the annular stator; and

[0043] a stator comprising a stator core and a plurality of electrical windings arranged in a distributed winding configuration;

[0044] The rotor assembly comprises:

[0045] a plurality of disc-shaped laminations; a rotor shaft; an encapsulation; a plurality of internal permanent magnets; and a plurality of surface mounted permanent magnets;

[0046] wherein a plurality of disc-shaped laminations are arranged on a rotor shaft in a stacked structure;

[0047] wherein the plurality of disc-shaped laminations include a plurality of magnetic pole portions,

[0048] wherein the plurality of pole sections include a plurality of internal cavities and a plurality of surface mount cavities;

[0049] wherein a plurality of internal permanent magnets are disposed in a plurality of internal cavities;

[0050] wherein a plurality of surface mounted permanent magnets are disposed in a plurality of surface mounted cavities; and

[0051] Therein, the enclosure encapsulates an outer surface defined by a plurality of disc-shaped laminations and a plurality of surface-mounted permanent magnets.

[0052] 15. An electric machine according to claim 14, wherein each of the plurality of surface mounted permanent magnets includes a cross-section modified to include an arcuate outwardly facing shape.

[0053] 16. An electric machine according to claim 15, wherein each of the plurality of surface mounted permanent magnets has a rectangular cross-section modified to include an arcuate outward side, wherein the arcuate outward side is coextensive with the outer circumference of the rotor assembly.

[0054] 17. An electric machine according to claim 15, wherein each of the plurality of surface-mounted permanent magnets has a trapezoidal cross-section modified to include an arcuate outward side, wherein the arcuate outward side is coextensive with the outer circumference of the rotor assembly.

[0055] 18. An electric machine according to claim 15, wherein each of the plurality of surface mounted permanent magnets has a triangular cross-section modified to include an arcuate outward side, wherein the arcuate outward side is coextensive with the outer circumference of the rotor assembly.

[0056] 19. The motor of claim 15, further comprising the motor being coupled to a vehicle wheel of a propulsion system of a vehicle.

[0057] 20. A rotor assembly for an electric motor, comprising:

[0058] a plurality of disc-shaped laminations; a rotor shaft; a plurality of interior permanent magnets; and a plurality of surface mounted permanent magnets;

[0059] wherein a plurality of disc-shaped laminations are arranged on a rotor shaft in a stacked structure;

[0060] wherein the plurality of disc-shaped laminations include a plurality of magnetic pole portions;

[0061] wherein the plurality of pole portions define a plurality of interior cavities and a plurality of surface mounting cavities;

[0062] wherein a plurality of internal permanent magnets are disposed in a plurality of internal cavities; and

[0063] Wherein, a plurality of surface mounted permanent magnets are arranged in a plurality of surface mounted cavities.

[0064] The above features and advantages and other features and advantages of the present teachings are readily apparent from the following detailed description of some of the best modes and other embodiments for carrying out the present teachings as defined in the appended claims when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] One or more embodiments will now be described by way of example with reference to the accompanying drawings, in which:

[0066] Figure 1 is a schematic diagram of a system including a multi-phase, multi-pole surface / interior permanent magnet motor / generator (S / IPM motor), a DC power supply, an inverter, and a controller according to the present disclosure.

[0067] Figure 2 A cross-sectional end view of an embodiment of an S / IPM motor according to the present disclosure is schematically shown.

[0068] Figures 3 to 8 An embodiment of a single-pole portion of a rotor for a S / IPM motor according to the present disclosure is schematically illustrated.

[0069] The drawings are not necessarily drawn to scale and present somewhat simplified representations of various features of the present disclosure disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes. Details related to these features will be determined in part by the specific intended application and use environment. DETAILED DESCRIPTION

[0070] As described and shown herein, the parts of the disclosed embodiments can be arranged and designed with various different configurations. Therefore, the following detailed description is not intended to limit the scope of the disclosure claimed for protection, but only represents its possible embodiments. In addition, although many specific details are set forth in the following description in order to provide a thorough understanding of the embodiments disclosed herein, some embodiments can be practiced without some of these details. In addition, for the purpose of clarity, some technical materials understood in the relevant art are not described in detail to avoid unnecessarily obscuring the disclosure. In addition, the disclosure as shown and described herein can be implemented in the absence of elements not specifically disclosed herein.

[0071] As used herein, the term "system" refers to mechanical and electrical hardware, software, firmware, electronic control components, processing logic and / or processor devices, alone or in combination, including but not limited to: application specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated or groups) that execute one or more software or firmware programs, memory devices that electrically store software or firmware instructions, combinational logic circuits and / or other components that provide the described functionality.

[0072] As used herein, the term "electrical machine" refers to an electric motor / generator device including a rotor and a stator that is capable of converting electrical power into mechanical power and / or converting mechanical power into electrical power through electromagnetic action.

[0073] Referring to the drawings, wherein like reference numerals designate like or similar parts throughout the several views. Figure 1 A system 100 is schematically shown, which includes a multi-phase, multi-pole, rotating surface / interior permanent magnet motor / generator (S / IPM motor) 10, which is arranged to generate torque and transmit the torque to an actuator 120 to achieve work, and a controller 130 that executes a control routine to control and manage its operation. In one embodiment, the system 100 is disposed on a vehicle (not shown). When disposed on a vehicle, the vehicle can include, but is not limited to, a mobile platform in the form of a commercial vehicle, an industrial vehicle, an agricultural vehicle, a bus, an airplane, a boat, a train, an all-terrain vehicle, a personal mobility device, a robot, etc. to achieve the purposes of the present disclosure. Alternatively, the system 100 can be an element of a fixed system.

[0074] The system 100 also includes an inverter 104 and a DC power source 102. The DC power source 102 is connected to the inverter 104 via a high voltage DC bus 103, and the inverter 104 is connected to the motor 10 via a plurality of power lines 106.

[0075] The inverter 104 includes a plurality of semiconductor switches (not shown) arranged and controllable to convert DC power to AC power and AC power to DC power using a pulse width modulation signal 108 or another control technique. The inverter 104 is arranged and controllable to convert DC power originating from the DC power source 102 into AC power to actuate the S / IPM motor 10 via electromagnetic action. When operating in a torque generating mode, the S / IPM motor 10 is controllable to rotate and generate mechanical torque, which is transmitted to the actuator 120 via a rotatable member 112 and a gear train 114. When operating in a generating mode, the S / IPM motor 10 is controllable to generate AC power from the mechanical torque originating from the actuator 120 via electromagnetic action, which is converted by the inverter 104 to DC power for storage in the DC power source 102. In one embodiment, the actuator 120 includes a vehicle wheel that transmits torque to the ground to achieve forward motion as part of the traction propulsion system of the vehicle. The DC power source 102 may be in the form of a rechargeable electrochemical battery device, a fuel cell, a supercapacitor, and / or another electrical energy storage / generation technology.

[0076] The controller 130 may be implemented as one or more digital computing devices and may include one or more processors 134 and a memory 132. A control routine 136 may be stored as an executable instruction set in the memory 132 and executed by one of the processors 134 of the controller 130. The controller 130 communicates with the inverter 104 to control its operation in response to execution of the control routine 136, thereby operating the S / IPM motor 10.

[0077] The term "controller" and related terms such as microcontroller, control module, module, control, control unit, processor and similar terms refer to one or more combinations of the following components: application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), electronic circuits, central processing units (e.g., microprocessors) and related memory components in the form of temporary and / or non-transitory memory components and storage devices (read-only, programmable read-only, random access, hard drives, etc.). Non-transitory memory components can store machine-readable instructions in the form of one or more software or firmware programs or routines, combinational logic circuits, input / output circuits and devices, signal conditioning and buffering circuits and other components that can be accessed by one or more processors to provide the described functions. Input / output circuits and devices include analog / digital converters and related devices that monitor inputs from sensors, where such inputs are monitored at a preset sampling frequency or in response to a triggering event. Software, firmware, programs, instructions, control routines, code, algorithms and similar terms refer to controller executable instruction sets including calibration and lookup tables.

[0078] The S / IPM motor 10 uses a combined surface mounted PM motor and interior PM motor topology. The combined use of surface and interior permanent magnets is advantageous in increasing torque density without changing the stator design, inverter current, etc. The combined use of surface and interior permanent magnets increases magnetic flux, thereby generating higher power at peak high speeds.

[0079] Figure 2 An embodiment of an S / IPM motor 10 is schematically shown. The S / IPM motor 10 includes a cylindrical rotor assembly 20 disposed on a rotor shaft 16 and disposed within an annular stator 50, wherein the rotor assembly 20 is coaxial with a rotor opening 60 formed in the stator 50. Other elements of the S / IPM motor 10, such as end caps, bearings, electrical connections, etc., are included but not shown. The S / IPM motor 10 is shown in the context of a radial axis 13 and a longitudinal axis 12, wherein the longitudinal axis 12 is defined by the rotor shaft 16.

[0080] The rotor assembly 20 includes a plurality of stamped ferrous laminations 22 arranged in a stack, assembled onto the rotor shaft 16, and encapsulated in an annular sleeve or enclosure 40. Each lamination 22 is a disc-shaped device formed to have a uniform thickness and a constant outer diameter, and has a centrally located shaft hole 26 and a plurality of pole portions 30. In one embodiment, the laminations 22 are manufactured by a stamping process.

[0081] The pole segments 30 are repeated around the circumference of the laminations 22 and define the number of poles of the rotor assembly 20. As shown, and by way of non-limiting example, there are eight pole segments 30, defining a number of four pole pairs for the rotor assembly 20. It should be understood that other numbers of pole segments 30 may be present in other embodiments, but are not limited thereto.

[0082] Each pole segment 30 includes a plurality of internal cavities 32 , which may be in a double V-shaped arrangement (as shown) or another arrangement. Other examples of arrangements are described below. Each pole segment 30 includes one or more surface cavities 34 .

[0083] The plurality of laminations 22 are assembled such that the rotor shaft 16 is inserted into the shaft hole 26 such that the pole portions 30 are aligned to form a plurality of internal cavities 32 and surface cavities 34 that are parallel to the longitudinal axis 12 defined by the rotor shaft 16. The plurality of internal cavities 32 receive and seat internal permanent magnets 33, which are prismatic elements having a rectangular, trapezoidal, dovetail, or other cross-sectional shape. The plurality of surface cavities 34 receive and seat surface mounted permanent magnets 35. For additional details regarding the plurality of internal cavities 32, the internal permanent magnets 33, the surface cavities 34, and the surface mounted permanent magnets 35, refer to Figures 3 to 8 is described in more detail.

[0084] Both or either of the internal permanent magnet 33 and the surface mounted permanent magnet 35 can be made of rare earth materials and can be described according to a longitudinal axis and a rectangular cross-sectional area with a major axis and a minor axis. Rare earth magnets are formed from alloys of rare earth materials, such as dysprosium reduced material or another suitable material. Other rare earth materials may include neodymium and samarium. Alternatively, either or both of the internal permanent magnet 33 and the surface mounted permanent magnet 35 can be made of non-rare earth materials, such as ferrite, alnico, iron cobalt (FeCo) and manganese bismuth (MnBi) or a combination thereof.

[0085] The annular enclosure 40 is made of carbon fiber or another material and encapsulates the outer peripheral surface of the rotor assembly 20. As a non-limiting example, the annular enclosure may alternatively be made of stainless steel, fiberglass, titanium alloy, etc. The annular enclosure 40 is arranged to provide a retaining force against the centrifugal force associated with the rotation of the rotor assembly 20.

[0086] External dimensions associated with the rotor assembly 20 include an outer diameter 29 . The outer diameter 29 is associated with the outer periphery 27 of the rotor assembly 20 and the annular enclosure 40 and is measured relative to the radial axis 13 .

[0087] The stator 50 includes a plurality of stamped ferrous laminations 52. Each lamination 52 is a disc-shaped device formed to have a uniform thickness, and each lamination has a centrally located inner hole 51 formed to accommodate the outer diameter 29 of the rotor assembly 20 including the annular enclosure 40. Each lamination 52 also includes a plurality of radially oriented, inwardly protruding teeth 56. The laminations 52 are arranged in a stack so that the inner holes 51 are aligned and the inwardly protruding teeth 56 are aligned. The laminations 52 are assembled into a single device. The rotor opening 60 is formed by the aligned inner holes 51 of the plurality of laminations 52, and a plurality of longitudinally oriented slots 58 are formed between the aligned inwardly protruding teeth 56 of the plurality of laminations 52.

[0088] The slots 57 are configured to accommodate the electrical windings 54 arranged in a distributed electrical winding assembly 70, which in one embodiment is made of stranded conductors. The stranded conductors may be made of any suitable material, such as copper. Internal dimensions associated with the stator 50 include an inner diameter 59 that defines the inner circumferential surface 28 of the stator 50. Alternatively, the electrical windings 54 may be arranged in a concentrated winding configuration.

[0089] An air gap 31 is formed between the outer peripheral surface of the rotor assembly 20 and the inner peripheral surface 28 of the stator 50 .

[0090] The distributed electric winding assembly 70 of the electric winding 54 in the stator 50 can be arranged to provide a rotating electric field arrangement, which provides a rotating magnetic field in the stator 50 by applying a multi-phase alternating current, which can be supplied by an integrated power inverter. In one embodiment, the multi-phase alternating current is a three-phase alternating current. During operation, the electromagnetic force induced in the electric winding 54 introduces a magnetic flux acting on the internal permanent magnets 33 and the surface-mounted permanent magnets 35 embedded in the rotor assembly 20, thereby applying a torque to cause the rotor assembly 20 to rotate around the rotor shaft 16 in the stator 50. Alternating current (AC) motors can be divided into AC induction motors and AC synchronous motors. In a rotating magnetic field type AC synchronous motor (in which the stator is provided with an armature winding and the rotor assembly is provided with a magnet winding), the rotor assembly is turned into an electromagnet by exciting the magnet winding of the rotor assembly, and the rotor assembly is rotated by applying a multi-phase alternating current to the stator. In applications where the power is derived from a DC power source, the multi-phase alternating current is generated by a power inverter.

[0091] The electrical winding of the stator 50 is arranged with a certain number of electrical phases and a certain number of electrical turns per phase. Depending on the specific arrangement, the number of electrical phases may be between 3 and 6, and the number of conductor layers may be between 4 and 12.

[0092] Specific geometric design parameters associated with the rotor assembly 20 and the stator 50 of the S / IPM motor 10 are identified, including a first set of geometric design parameters associated with the rotor assembly 20 and a second set of geometric design parameters associated with the stator 50. Preferred ranges for the first and second sets of geometric design parameters are selected to achieve motor operating parameters including high drive cycle efficiency (e.g., greater than 90% peak efficiency over a wide speed / load operating range), high torque density, a wide peak power range, and a maximum speed of 21,000 rpm or greater.

[0093] Figures 3 to 8 Schematic cross-sectional cutaway end views each depict a fragment of an embodiment of an S / IPM motor 310 showing a single pole portion of a rotor assembly mounted on a rotor shaft and a corresponding portion of a stator with an air gap disposed therebetween.

[0094] Figure 3 Schematically illustrated is an embodiment of a magnetic pole section 330 for a rotor assembly 320, the magnetic pole section 330 being composed of a plurality of stamped ferrous laminations 322 arranged in a stack, the laminations 322 being similar to those of reference 1. Figure 2 The rotor assembly 320 may be used with reference to the laminations 22 described above. Figure 1 and Figure 2In the S / IPM motor 10 with the stator 50 described. In this embodiment, the pole portion 330 includes an internal permanent magnet portion 331 arranged in a double V-shaped structure, which includes a first internal cavity 332A and a second internal cavity 332B arranged in a V-shaped structure, and contains first and second internal permanent magnets 333A and 333B, respectively. In one embodiment, the first internal cavity 332A and the associated first internal permanent magnet 333A can have a smaller cross-sectional area than the second internal cavity 332B and the second internal permanent magnet 333B. In this embodiment, the bridge 338 is arranged between the ends of the first internal permanent magnet 333A and the second internal permanent magnet 333B and the outer periphery 339 of the rotor assembly 320. In this embodiment, the surface mounted permanent magnet 335 is disposed in the surface cavity 334. In this embodiment, the surface mounted permanent magnet 335 has a rectangular cross-section, which is modified to include an arc-shaped outer side 335A coextensive with the outer periphery 339 of the rotor assembly 320. Alternatively, the surface mounted permanent magnet 335 may have a rectangular cross section. In one embodiment, the surface cavity 334 includes an axial channel 337 formed at the bottom, and a through hole 336 is formed in the axial channel 337 between the rotor assembly 320 and the surface mounted permanent magnet 335. In one embodiment, the through hole 336 may be employed in a cooling system. The enclosure 340 is disposed on the outer periphery 339.

[0095] Figure 4 Schematically illustrated is an embodiment of a magnetic pole section 430 for a rotor assembly 420, the magnetic pole section 430 being composed of a plurality of stamped ferrous laminations 422 arranged in a stack, the laminations 422 being similar to those of reference 4 Figure 2 The rotor assembly 420 may be used with reference to Figure 1 and Figure 2 4. In the S / IPM motor 10 with stator 50 described above. In this embodiment, pole portion 430 includes an internal permanent magnet portion 431 arranged in a double V-shaped structure, which includes a first internal cavity 432A and a second internal cavity 432B arranged in a V-shaped structure, and contains first and second internal permanent magnets 433A and 433B, respectively. In one embodiment, the first internal cavity 432A and the associated first internal permanent magnet 433A can have a smaller cross-sectional area than the second internal cavity 432B and the second internal permanent magnet 433B. In this embodiment, bridge 438 is arranged between the ends of the first internal permanent magnet 433A and the second internal permanent magnet 433B and the outer periphery 439 of the rotor assembly 420. In this embodiment, surface mounted permanent magnet 435 is disposed in surface cavity 434. In this embodiment, surface mounted permanent magnet 435 has an arcuate cross-section, which includes an arcuate outward side 435A coextensive with the outer periphery 439 of the rotor assembly 420. The enclosure 440 is arranged on the outer periphery 439 .

[0096] Figure 5 Schematically illustrates an embodiment of a magnetic pole section 530 for a rotor assembly 520, the magnetic pole section 530 being composed of a plurality of stamped ferrous laminations 522 arranged in a stack, the laminations 522 being similar to those of reference Figure 2 The rotor assembly 520 may be used with reference to Figure 1 and Figure 2 53B. In the S / IPM motor 10 with stator 50 described. In this embodiment, pole portion 530 includes an internal permanent magnet portion 531 arranged in a double V-shaped structure, which includes a first internal cavity 532A and a second internal cavity 532B arranged in a V-shaped structure, and contains first and second internal permanent magnets 533A and 533B, respectively. In one embodiment, the first internal cavity 532A and the associated first internal permanent magnet 533A can have a smaller cross-sectional area than the second internal cavity 532B and the second internal permanent magnet 533B. In this embodiment, the disc-shaped laminations of rotor assembly 520 have a gap 538 between the ends of the first internal permanent magnet 533A and the second internal permanent magnet 533B and the outer periphery 539 of the rotor assembly 520. In this embodiment, surface mounted permanent magnets 535 are disposed in surface cavities 534. In this embodiment, the surface mounted permanent magnet 535 has an arcuate cross-section including an arcuate outward side 535A coextensive with an outer periphery 539 of the rotor assembly 520. An enclosure 540 is disposed on the outer periphery 539.

[0097] Figure 6 Schematically illustrated is an embodiment of a magnetic pole section 630 for a rotor assembly 620, the magnetic pole section 630 being composed of a plurality of stamped ferrous laminations 622 arranged in a stack, the laminations 622 being similar to those of reference 1. Figure 2 The rotor assembly 620 may be used with reference to Figure 1 and Figure 2 63. In the S / IPM motor 10 with the stator 50 described above, a pole portion 630 includes an inner permanent magnet portion 631 arranged in a single V-shaped structure, including an inner cavity 632 arranged in a V-shaped structure, and contains an inner permanent magnet 633. In this embodiment, a bridge 638 is arranged in the disc-shaped laminations of the rotor assembly 620, between the end of the first inner permanent magnet 633 and the outer periphery 639 of the rotor assembly 620. In this embodiment, a surface mounted permanent magnet 635 is arranged in the surface cavity 634. In this embodiment, the surface mounted permanent magnet 635 has a rectangular cross-section, which includes an arc-shaped outer side 635A coextensive with the outer periphery 639 of the rotor assembly 620. The enclosure 640 is arranged on the outer periphery 639.

[0098] Figure 7Schematically illustrated is an embodiment of a magnetic pole section 730 for a rotor assembly 720, the magnetic pole section 730 being composed of a plurality of stamped ferrous laminations 722 arranged in a stack, the laminations 722 being similar to those of reference 70. Figure 2 The rotor assembly 720 may be used with reference to Figure 1 and Figure 2 5. In the S / IPM motor 10 with stator 50 described above. In this embodiment, the pole portion 730 includes an internal permanent magnet portion 731 arranged in a U-shaped structure, which includes a first internal cavity 732A arranged in a V-shaped structure and contains a first internal permanent magnet 733A, and a second internal cavity 732B arranged in a U-shaped structure, and contains the first internal permanent magnet 733A and the third internal permanent magnet 733C, respectively. In one embodiment, the first internal cavity 732A and the associated first internal permanent magnet 733A can have a smaller cross-sectional area than the second internal cavity 732B and the second internal permanent magnet 733B. In this embodiment, the bridge 738 is arranged in a disc-shaped lamination between the ends of the first internal permanent magnet 733A and the second internal permanent magnet 733B and the outer periphery 739 of the rotor assembly 720. In this embodiment, the surface mounted permanent magnet 735 is disposed in the surface cavity 734. In this embodiment, the surface mounted permanent magnet 735 has a trapezoidal cross-section including an arcuate outward side 735A coextensive with an outer periphery 739 of the rotor assembly 720. An enclosure 740 is disposed on the outer periphery 739.

[0099] Figure 8 Schematically illustrates an embodiment of a magnetic pole section 830 for a rotor assembly 820, the magnetic pole section 830 being composed of a plurality of stamped ferrous laminations 822 arranged in a stack, the laminations 822 being similar to those of reference Figure 2 The rotor assembly 820 may be used with reference to Figure 1 and Figure 2 83B. In the S / IPM motor 10 with the stator 50 described above. In this embodiment, the pole portion 830 includes an internal permanent magnet portion 831 arranged in a double V-shaped structure, which includes a first internal cavity 832A and a second internal cavity 832B arranged in a V-shaped structure, and contains first and second internal permanent magnets 833A and 833B, respectively. In one embodiment, the first internal cavity 832A and the associated first internal permanent magnet 833A can have a smaller cross-sectional area than the second internal cavity 832B and the second internal permanent magnet 833B. In this embodiment, the surface mounted permanent magnet 835 is disposed in the surface cavity 834. In this embodiment, the surface mounted permanent magnet 835 has a triangular cross-section, which includes an arc-shaped outer side 835A that is coextensive with the outer periphery 839 of the rotor assembly 820. The enclosure 840 is disposed on the outer periphery 839.

[0100] The concepts described herein provide an S / IPM motor comprising a rotor assembly arranged with a plurality of pole sections, each pole section comprising an internal permanent magnet section and a surface mounted permanent magnet, wherein an enclosure section is arranged on an outer periphery of the rotor assembly. Embodiments described herein may provide increased torque density, increased power density, reduced flux leakage, and other benefits compared to motors of similar size lacking such an arrangement. This provides a better potential to balance cost, energy consumption, and performance by introducing design freedoms that would not otherwise be possible.

[0101] Embodiments of the motor described herein are configured to simultaneously achieve operating parameters associated with torque, speed, power, efficiency, packaging and other constraints, including operation using a 48V DC power supply. The geometric design parameters associated with the drive cycle efficiency and active material cost of the permanent magnets in the rotor assembly can have the following characteristics. The rotor permanent magnets can be configured as a simple V-shaped arrangement or a flat type to reduce the mass of the magnets, or to reduce the number of permanent magnet pieces used in the rotor assembly. The first and second groups of geometric design parameters are determined to ensure the minimum use of permanent magnets while meeting other performance criteria, such as torque density, high drive cycle efficiency, prevention of permanent demagnetization, and minimum torque pulsation.

[0102] When used, the rotor bridge thickness ranges from 0.8mm to 2.0mm to minimize flux leakage, improve power factor, minimize magnet usage, and meet stress requirements at maximum operating speeds between 18,000 and 25,000rpm. When applicable, for example, in the case of a V-type layout, a center column can be introduced into the rotor body to increase mechanical robustness.

[0103] Several features were introduced to enhance motor performance. These features include configuring the stator design to a distributed winding configuration instead of fractional slot concentrated winding for improved field weakening performance, reduced core losses, and better overload thermal capability. Geometric design parameters were ranged to achieve low copper and core losses, high torque density, high drive cycle efficiency, and minimal torque ripple.

[0104] The detailed description and the accompanying drawings or figures are support and description of the present teaching, but the scope of the present teaching is limited only by the claims. Although some best modes and other embodiments for carrying out the present teaching have been described in detail, there are various alternative designs and embodiments for practicing the present teaching defined in the appended claims.

Claims

1. A rotor assembly for an electric motor, comprising: a plurality of disc-shaped laminations; Rotor shaft; Encapsulation; multiple internal permanent magnets; and a plurality of surface mounted permanent magnets; wherein a plurality of disc-shaped laminations are arranged on a rotor shaft in a stacked structure; wherein the plurality of disc-shaped laminations include a plurality of magnetic pole portions, wherein the plurality of pole sections include a plurality of internal cavities and a plurality of surface mount cavities; wherein a plurality of internal permanent magnets are disposed in a plurality of internal cavities; wherein a plurality of surface mounted permanent magnets are disposed within a plurality of surface mounted cavities; and Therein, the enclosure encapsulates an outer surface defined by a plurality of disc-shaped laminations and a plurality of surface-mounted permanent magnets. 2 . The rotor assembly of claim 1 , wherein each of the plurality of surface mounted permanent magnets comprises a cross-section modified to include an arcuate outwardly facing shape. 3 . The rotor assembly of claim 2 , wherein each of the plurality of surface mounted permanent magnets has a rectangular cross-section modified to include an arc-shaped outer side. 4 . The rotor assembly of claim 2 , wherein each of the plurality of surface mounted permanent magnets has a trapezoidal cross-section modified to include an arc-shaped outer side. 5 . The rotor assembly of claim 2 , wherein each of the plurality of surface mounted permanent magnets has a triangular cross-section modified to include an arc-shaped outer side. 6 . The rotor assembly of claim 2 , wherein each of the plurality of surface mounted permanent magnets has an arcuate cross-section including an arcuate outward side.

7. The rotor assembly of claim 2, wherein the arc is outwardly coextensive with an outer circumference of the rotor assembly.

8. The rotor assembly of claim 1, wherein the encapsulator comprises a carbon fiber fabric encapsulating an outer surface defined by the plurality of disk-shaped laminations and the plurality of surface-mounted permanent magnets.

9. The rotor assembly of claim 1, wherein the plurality of interior cavities defined for the plurality of pole sections comprise rectangular prisms arranged in a single V-shaped configuration.

10. A rotor assembly for an electric motor, comprising: a plurality of disc-shaped laminations; Rotor shaft; multiple internal permanent magnets; and a plurality of surface mounted permanent magnets; wherein a plurality of disk-shaped laminations are arranged on a rotor shaft in a stacked structure; wherein the plurality of disk-shaped laminations include a plurality of magnetic pole portions; wherein the plurality of pole portions define a plurality of interior cavities and a plurality of surface mounting cavities; wherein a plurality of internal permanent magnets are disposed in a plurality of internal cavities; and Wherein, a plurality of surface mounted permanent magnets are arranged in a plurality of surface mounted cavities.

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