Rotor for permanent magnet motor
By removing the bridge in the stack of the IPM motor rotor assembly, the problems of low torque density and flux leakage of high-speed IPM rotors are solved, and higher torque density and power density are achieved, and thermal management is improved.
Patent Information
- Application Number
- CN202410020294.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-11-07
- Filing Date
- 2024-01-05
- Publication Date
- 2025-05-09
AI Technical Summary
Due to the presence of the retaining sleeve, the air gap between the rotor assembly and the stator of the IPM motor is effectively increased, resulting in a low torque density of the high-speed IPM rotor and the presence of the bridge portion leads to flux leakage.
By removing the bridges in the laminate forming the rotor assembly, flux leakage is reduced, thereby increasing torque density and power density.
Effectively reduces flux leakage, improves torque and power density, improves thermal management, and is adapted to available packaging spaces.
Smart Images
Figure CN119966113A_ABST
Abstract
Description
Background Art
[0001] Electric motor / generators including interior permanent magnet (IPM) motors may be used as torque-producing devices on vehicles. However, high-speed IPM rotors with retaining sleeves typically suffer from lower torque density compared to non-sleeved rotors due to the effective increase in the air gap between the rotor assembly and the stator due to the presence of the retaining sleeve.
[0002] A rotor assembly for an IPM motor includes a laminate stack having a plurality of pole segments formed by permanent magnets inserted into and secured in a plurality of cavities formed in the laminate stack. The laminates of the laminate stack have web portions and bridges to provide structural and mechanical integrity near the plurality of cavities. In some embodiments, the webs may be removed to reduce leakage flux and compensate for lower torque. However, the bridges are retained to maintain laminate integrity, resulting in flux leakage. The thickness of the bridges and / or webs may be determined by manufacturing capabilities rather than centrifugal stress at high speeds.
[0003] There may be benefits to having an electric machine that has 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] The concepts described herein provide a permanent magnet electric machine having a rotor assembly that advantageously reduces magnetic flux leakage by removing bridges in at least a portion of the laminations forming the rotor assembly. This can be used to increase torque density and power density compared to a similarly constructed electric machine having bridges in all of the laminations forming the rotor assembly.
[0005] One aspect of the present disclosure may include a rotor assembly for an electric machine, the rotor assembly comprising: a plurality of first disc-shaped laminations, a plurality of second disc-shaped laminations; a rotor shaft; a wrap; and a plurality of permanent magnets; wherein the plurality of first disc-shaped laminations and the plurality of second disc-shaped laminations are arranged in a stack on the rotor shaft. Each of the plurality of first disc-shaped laminations includes a first inner portion and a plurality of first outer portions, the first inner portion and the plurality of first outer portions defining a plurality of first cavities, wherein the plurality of first outer portions are fixed to the first inner portion via a plurality of bridges. Each of the plurality of second disc-shaped laminations includes a second inner portion and a plurality of second outer portions, the second inner portion and the plurality of second outer portions defining a plurality of second cavities, wherein the plurality of second outer portions are fixed to the second inner portion via a plurality of second webs, and no bridges are present.
[0006] Another aspect of the present disclosure may include: the plurality of first disk-shaped laminations are aligned with the plurality of second disk-shaped laminations so that the plurality of first cavities are aligned with the plurality of second cavities to form a plurality of axially arranged cavities, wherein the plurality of axially arranged cavities define a plurality of radially arranged magnetic pole segments.
[0007] Another aspect of the present disclosure may include the plurality of permanent magnets being disposed in the plurality of axially disposed cavities.
[0008] Another aspect of the present disclosure may include the plurality of axially disposed cavities defining a plurality of prisms arranged in a single V-shaped arrangement for each of the plurality of pole segments.
[0009] Another aspect of the present disclosure may include the plurality of axially disposed cavities defining a plurality of prisms arranged in a double V-shaped arrangement for each of the plurality of pole segments.
[0010] Another aspect of the present disclosure may include the plurality of axially disposed cavities defining a plurality of prisms arranged in a U-shaped arrangement for each of the plurality of pole segments.
[0011] Another aspect of the present disclosure may include that the enclosure is arranged to encapsulate an outer peripheral surface of the rotor assembly defined by the first plurality of disc-shaped laminations and the second plurality of disc-shaped laminations.
[0012] Another aspect of the present disclosure may include that the encapsulator is a carbon fiber fabric encapsulating an outer peripheral surface of the rotor assembly.
[0013] Another aspect of the present disclosure may include: the stacked arrangement of the plurality of first disk-shaped laminations and the plurality of second disk-shaped laminations on the rotor shaft includes a first one of the plurality of first disk-shaped laminations being disposed on a first end of the stack, and a second one of the plurality of first disk-shaped laminations being disposed on a second end of the stack.
[0014] Another aspect of the present disclosure may include a third one of the first plurality of disc-shaped laminations being disposed in a middle portion of the stack.
[0015] Another aspect of the present disclosure may include a permanent magnet rotor assembly for an electric machine, the rotor assembly comprising: a plurality of first disc-shaped laminations, a plurality of second disc-shaped laminations; and a rotor shaft. The plurality of first disc-shaped laminations and the plurality of second disc-shaped laminations are arranged in a staggered stack on the rotor shaft, wherein each of the plurality of first disc-shaped laminations comprises a first inner portion and a plurality of first outer portions, and the first inner portion and the plurality of first outer portions define a plurality of first cavities. The plurality of first outer portions are fixed to the first inner portion via a first web element and a plurality of bridges. Each of the plurality of second disc-shaped laminations comprises a second inner portion and a plurality of second outer portions, the second inner portion and the plurality of second outer portions define a plurality of second cavities, wherein the plurality of second outer portions are fixed to the second inner portion via a plurality of second webs, and there are no bridges.
[0016] Another aspect of the present disclosure may include: the plurality of first disk-shaped laminations are aligned with the plurality of second disk-shaped laminations so that the plurality of first cavities are aligned with the plurality of second cavities to form a plurality of axially arranged cavities, wherein the plurality of axially arranged cavities define a plurality of radially arranged magnetic pole segments.
[0017] Another aspect of the present disclosure may include an electrified drive system for a vehicle, the electrified drive system including: a DC power supply, a multi-phase power inverter, a multi-phase rotating electric machine, and a torque actuator, wherein the multi-phase rotating electric machine includes a rotor assembly and a stator. The rotor assembly includes a plurality of first disc-shaped laminations, a plurality of second disc-shaped laminations, and a rotor shaft. The plurality of first disc-shaped laminations and the plurality of second disc-shaped laminations are arranged in a stack on the rotor shaft, wherein each of the plurality of first disc-shaped laminations includes a first inner portion and a plurality of first outer portions, the first inner portion and the plurality of first outer portions define a plurality of first cavities, and the plurality of first outer portions are fixed to the first inner portion via a first web and a plurality of bridges. Each of the plurality of second disc-shaped laminations includes a second inner portion and a plurality of second outer portions, the second inner portion and the plurality of second outer portions define a plurality of second cavities, wherein the plurality of second outer portions are fixed to the second inner portion via a plurality of second webs, and there is no bridge.
[0018] The present invention also includes the following technical solutions:
[0019] Solution 1. A rotor assembly for a motor, comprising:
[0020] a plurality of first disc-shaped laminations, a plurality of second disc-shaped laminations; a rotor shaft; an enclosure; and a plurality of permanent magnets;
[0021] wherein the plurality of first disc-shaped laminations and the plurality of second disc-shaped laminations are arranged in a stack on the rotor shaft;
[0022] wherein each of the plurality of first disc-shaped laminations comprises a first inner portion and a plurality of first outer portions, the first inner portion and the plurality of first outer portions defining a plurality of first cavities;
[0023] wherein the plurality of first outer portions are fixed to the first inner portion via a first web and a plurality of bridge portions;
[0024] wherein each of the second plurality of disc-shaped laminations comprises a second inner portion and a plurality of second outer portions, the second inner portion and the plurality of second outer portions defining a plurality of second cavities; and
[0025] Therein, the plurality of second outer parts are fixed to the second inner part via a plurality of second webs, and no bridge portion exists.
[0026] Solution 2. The rotor assembly according to Solution 1,
[0027] wherein the plurality of first disk-shaped laminations are aligned with the plurality of second disk-shaped laminations such that the plurality of first cavities are aligned with the plurality of second cavities to form a plurality of axially disposed cavities; and
[0028] Wherein, the plurality of axially arranged cavities define a plurality of radially arranged magnetic pole segments.
[0029] Option 3. A rotor assembly according to Option 2, wherein the plurality of permanent magnets are disposed in the plurality of axially disposed cavities.
[0030] Option 4. A rotor assembly according to Option 2, wherein the plurality of axially arranged cavities define a plurality of prisms arranged in a single V-shaped arrangement structure for each of the plurality of magnetic pole segments.
[0031] Option 5. A rotor assembly according to Option 2, wherein the plurality of axially disposed cavities define a plurality of prisms arranged in a double V-shaped arrangement for each of the plurality of magnetic pole segments.
[0032] Option 6. A rotor assembly according to Option 2, wherein the plurality of axially disposed cavities define a plurality of prisms arranged in a U-shaped arrangement for each of the plurality of magnetic pole segments.
[0033] Option 7. The rotor assembly according to Option 1, wherein the enclosure is arranged to encapsulate an outer surface of the rotor assembly defined by the plurality of first disc-shaped laminations and the plurality of second disc-shaped laminations.
[0034] Option 8. The rotor assembly according to Option 7, wherein the enclosure comprises a carbon fiber fabric encapsulating an outer peripheral surface of the rotor assembly.
[0035] Option 9. A rotor assembly according to Option 1, wherein the stacked arrangement of the plurality of first disc-shaped laminations and the plurality of second disc-shaped laminations on the rotor shaft includes: a first one of the plurality of first disc-shaped laminations is disposed on a first end of the stack, and a second one of the plurality of first disc-shaped laminations is disposed on a second end of the stack.
[0036] Embodiment 10. The rotor assembly of embodiment 9 comprises a third one of the plurality of first disc-shaped laminations disposed in a middle portion of the stack.
[0037] Solution 11. A permanent magnet rotor assembly for an electric machine, comprising:
[0038] a plurality of first laminations, a plurality of second laminations; and a rotor shaft;
[0039] Wherein, the plurality of first laminations and the plurality of second laminations are arranged in a staggered stack on the rotor shaft;
[0040] wherein each of the plurality of first laminations comprises a first inner portion and a plurality of first outer portions, the first inner portion and the plurality of first outer portions defining a plurality of first cavities;
[0041] wherein the plurality of first outer portions are fixed to the first inner portion via a first web and a plurality of bridge portions;
[0042] wherein each of the second plurality of laminations comprises a second inner portion and a plurality of second outer portions, the second inner portion and the plurality of second outer portions defining a plurality of second cavities;
[0043] wherein the plurality of second outer portions are fixed to the second inner portion via a plurality of second webs; and
[0044] There is no bridge portion among the plurality of second outer portions.
[0045] Solution 12. The rotor assembly according to Solution 11:
[0046] wherein the plurality of first laminations are aligned with the plurality of second laminations such that the plurality of first cavities are aligned with the plurality of second cavities to form a plurality of axially disposed cavities; and
[0047] Wherein, the plurality of axially arranged cavities define a plurality of radially arranged magnetic pole segments.
[0048] Embodiment 13. A rotor assembly according to embodiment 12, wherein the plurality of axially arranged cavities define a plurality of prisms arranged in a single V-shaped arrangement structure for each of the plurality of magnetic pole segments.
[0049] Embodiment 14. A rotor assembly according to embodiment 12, wherein the plurality of axially disposed cavities define a plurality of prisms arranged in a double V-shaped arrangement for each of the plurality of magnetic pole segments.
[0050] Embodiment 15. A rotor assembly according to embodiment 12, wherein the plurality of axially arranged cavities define a plurality of prisms arranged in a U-shaped arrangement structure for each of the plurality of magnetic pole segments.
[0051] Aspect 16. The rotor assembly according to aspect 11, further comprising an enclosure, wherein the enclosure is arranged to encapsulate an outer peripheral surface defined by the plurality of first laminations and the plurality of second laminations.
[0052] Embodiment 17. The rotor assembly according to embodiment 16, wherein the encapsulant comprises a carbon fiber fabric encapsulating the outer peripheral surface.
[0053] Option 18. A rotor assembly according to Option 11, wherein the staggered stacking arrangement of the plurality of first laminations and the plurality of second laminations on the rotor shaft includes: a first one of the plurality of first laminations is disposed on a first end of the stack, and a second one of the plurality of first laminations is disposed on a second end of the stack.
[0054] Embodiment 19. The rotor assembly of embodiment 18 comprises a third one of the plurality of first laminations disposed in a middle portion of the stack.
[0055] Solution 20. An electrified transmission system for a vehicle, comprising:
[0056] DC power supplies, multiphase power inverters, multiphase rotating electrical machines, and torque actuators;
[0057] Wherein, the multi-phase rotating electrical machine comprises a rotor assembly and a stator;
[0058] Wherein, the rotor assembly comprises a plurality of first disc-shaped laminations, a plurality of second disc-shaped laminations; and a rotor shaft;
[0059] wherein the plurality of first disc-shaped laminations and the plurality of second disc-shaped laminations are arranged in a stack on the rotor shaft;
[0060] wherein each of the plurality of first disc-shaped laminations comprises a first inner portion and a plurality of first outer portions, the first inner portion and the plurality of first outer portions defining a plurality of first cavities;
[0061] wherein the plurality of first outer portions are fixed to the first inner portion via a first web and a plurality of bridge portions;
[0062] wherein each of the second plurality of disc-shaped laminations comprises a second inner portion and a plurality of second outer portions, the second inner portion and the plurality of second outer portions defining a plurality of second cavities; and
[0063] Therein, the plurality of second outer parts are fixed to the second inner part via a plurality of second webs, and no bridge portion exists.
[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 permanent magnet motor / generator, a DC power supply, an inverter, and a controller according to the present disclosure.
[0067] Figure 2 is a schematic diagram of a cut-away end view of an embodiment of an interior permanent magnet (IPM) motor according to the present disclosure.
[0068] Figure 3 is a schematic diagram of a cross-sectional end view of a portion of a first lamination of a stator and a rotor assembly of an IPM machine according to the present disclosure.
[0069] Figure 4 is a schematic diagram of a cross-sectional end view of a portion of a second lamination of a stator and a rotor assembly of an IPM machine according to the present disclosure.
[0070] Figure 5 is a schematic diagram of an isometric view of one embodiment of a rotor assembly according to the present disclosure.
[0071] Figure 6 is a schematic diagram of an isometric view of another embodiment of a rotor assembly according to the present disclosure.
[0072] The drawings are not necessarily drawn to scale and present somewhat simplified representations of various features of the present disclosure as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes. The details associated with such features will be determined in part by the specific intended application and use environment. DETAILED DESCRIPTION
[0073] As described and illustrated herein, the parts of the disclosed embodiments can be arranged and designed according to a variety of different configurations. Therefore, the following detailed description is not intended to limit the scope of the present disclosure as claimed, 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 sake of clarity, some technical materials understood in the relevant technical field are not described in detail to avoid unnecessarily obscuring the present disclosure. In addition, as illustrated and described herein, the present disclosure can be practiced without the presence of elements not specifically disclosed herein.
[0074] The present disclosure allows for embodiments in many different forms. Representative examples of the present disclosure are shown in the accompanying drawings and described in detail herein as non-limiting examples of the disclosed principles. For this reason, elements and limitations described herein but not explicitly set forth in the claims should not be incorporated into the claims individually or collectively by implication, inference or otherwise.
[0075] For the purposes of the present description, unless otherwise stated, the use of the singular includes the plural and vice versa, the terms "and" and "or" shall be both conjunctions and disjunctive conjunctions, and the terms "include," "comprise," "contain," "have," and the like shall mean "including but not limited to." In addition, approximate terms such as "approximately," "almost," "substantially," "roughly," "approximately," and the like may be used herein in the sense of "at, close to, or nearly at," or "within 0-5% thereof," or "within an acceptable manufacturing tolerance," or a logical combination thereof.
[0076] As used herein, the term "system" refers to mechanical and electrical hardware, software, firmware, electronic control component parts, 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 grouped) 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.
[0077] As used herein, terms such as "vertical", "horizontal", "left", "right", "upper", "lower", "top", "bottom" and similar expressions are non-limiting terms that merely describe the various elements as shown in the figures and are not intended to limit the scope of the present disclosure.
[0078] As used herein, the term "electric machine" refers to an electric motor / generator device including a rotor and a stator that is capable of converting electrical power to mechanical power and / or converting mechanical power to electrical power through electromagnetic effort.
[0079] Referring to the drawings, wherein like reference numerals designate the same or similar components throughout the several views, Figure 1 and Figure 2 Schematically illustrated are elements of an electrified drive system 100 consisting of a DC power source 102, a multi-phase power inverter 104, a multi-phase rotary electric motor / generator (motor) 10, and a torque actuator 120, the operation of which is monitored and controlled by a controller 130. In one embodiment, the electrified drive system 100 is arranged to generate torque and transmit the torque to the torque actuator 120, which may be in the form of one or more drive wheels to achieve work, such as propulsion, when employed on a vehicle. The controller 130 executes a control routine to control and manage the operation of the multi-phase power inverter 104. In one embodiment, the electrified drive system 100 is disposed on a vehicle and is capable of generating traction torque for vehicle propulsion. When disposed on a vehicle, the vehicle may include, but is not limited to, a mobile platform in the form of a commercial vehicle, an industrial vehicle, an agricultural vehicle, a passenger car, an aircraft, a watercraft, a train, an all-terrain vehicle, a personal mobility device, a robot, etc. for achieving the purposes of the present disclosure. Non-limiting examples of vehicles that employ the electrified powertrain 100 include electric vehicles (EVs) and various hybrid electric vehicles (HEVs). Alternatively, the electrified powertrain 100 may be an element of a stationary system.
[0080] 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 multi-phase power inverter 104 to control the operation of the multi-phase power inverter 104 in response to the execution of the control routine 136, thereby operating the electric machine 10.
[0081] 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: an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), an electronic circuit, a central processing unit such as a microprocessor, and associated memory components in the form of temporary and / or non-temporary memory components and storage devices (read-only, programmable read-only, random access, hard drive, etc.). The non-temporary memory components are capable of storing 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 accessible by one or more processors to provide the described functionality. The 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 mean controller executable instruction sets including calibration and lookup tables.
[0082] The electric machine 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 formed in the stator 50. Other elements of the electric machine 10, such as end caps, shaft bearings, electrical connections, etc., are included but not shown. The electrical windings of the stator 50 are arranged to have 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.
[0083] The multiphase power inverter 104 includes a plurality of semiconductor switches arranged and controllable to convert DC electric power to AC electric power and to convert AC electric power to DC electric power using a pulse width modulation signal 108 or another control technique. The multiphase power inverter 104 is arranged and controllable to convert DC electric power originating from the DC power source 102 to AC electric power to actuate the motor 10 via electromagnetic action. The motor 10 can be controlled to rotate and generate mechanical torque, which is transmitted to the torque actuator 120 via the rotatable member 112 and the gear train 114 when operating in the torque generation mode. The motor 10 can be controlled to generate AC electric power from the mechanical torque originating from the torque actuator 120 via electromagnetic action, which is converted to DC electric power by the multiphase power inverter 104 when operating in the electric power generation mode, so as to be stored in the DC power source 102. In one embodiment, the torque actuator 120 includes a vehicle wheel, which transmits torque to the ground surface to achieve forward motion as part of a traction propulsion system.
[0084] The DC power source 102 may be a rechargeable electrochemical battery device, a fuel cell, a supercapacitor, and / or another electrical energy storage / generation technology. The DC power source 102 is connected to a multi-phase power inverter 104 via a high voltage DC bus 103, and the multi-phase power inverter 104 is connected to the motor 10 via a plurality of power lines 106.
[0085] Figure 2 An embodiment of an electric machine 10 is schematically illustrated, which in one embodiment is an interior permanent magnet (IPM) device. The IPM electric machine 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 IPM electric machine 10, such as end caps, shaft bearings, electrical connections, etc., are included but not shown. The IPM electric machine 10 is illustrated with a radial axis 13 and a longitudinal axis 12, wherein the longitudinal axis 12 is defined by the rotor shaft 16.
[0086] The rotor assembly 20 includes a plurality of first disc-shaped laminations 21 interleaved and arranged in a stack with a plurality of second disc-shaped laminations 22. Figure 3 As described in additional detail in , each of the first disc-shaped laminations 21 and the second disc-shaped laminations 22 includes an inner portion 23 and an outer portion 24, which define and surround a plurality of cavities 32 that accommodate and house a plurality of permanent magnets 33. The first disc-shaped laminations 21 are interleaved with the second disc-shaped laminations 22, and are assembled onto the rotor shaft 16 and enclosed in an annular sleeve or enclosure 40. Each of the first disc-shaped laminations 21 and the second disc-shaped laminations 22 is a stamped sheet formed of a ferrous material and manufactured using a stamping process. Each of the first disc-shaped laminations 21 and the second disc-shaped laminations 22 is a disc-shaped device formed with a uniform thickness and a constant outer diameter, and has a centrally located axial hole 26 and a plurality of pole segments 30 formed thereon. A single pole segment of the pole segments 30 is shown. Reference Figure 3 To describe additional details related to the embodiment of the first disc-shaped lamination 21, and with reference to Figure 4 Additional details related to an embodiment of the second disc-shaped lamination stack 22 will be described.
[0087] Reference again Figure 2 , the pole segments 30 are repeated around the outer circumferential portion of each of the first disk-shaped laminations 21 and the second disk-shaped laminations 22, and define the number of magnetic poles of the rotor assembly 20. As shown, and as a non-limiting example, there are eight pole segments 30, thereby defining a number of four magnetic pole pairs of the rotor assembly 20. It is appreciated that in other embodiments, there may be other numbers of pole segments 30 without limitation.
[0088] Each of the pole segments 30 includes a plurality of cavities 32, which may be arranged in a double V-shaped arrangement (as shown) or another arrangement. As non-limiting examples, other examples of arrangements of the pole segments 30 and the plurality of cavities 32 may include a plurality of cavities 32 arranged in a single V-shaped arrangement, a U-shaped arrangement, or another arrangement.
[0089] The plurality of first and second disk-shaped laminations 21, 22 are assembled with the rotor shaft 16 inserted into the shaft hole 26 so that the pole segments 30 are concentrically aligned to define and form a plurality of cavities 32 parallel to the longitudinal axis 12 defined by the rotor shaft 16. The plurality of cavities 32 accommodate and house a corresponding plurality of permanent magnets 33, which are prismatic elements having rectangular, trapezoidal, dovetail or other cross-sectional shapes. Figure 3 and Figure 4 Additional details related to the plurality of cavities 32 and permanent magnets 33 are described in greater detail.
[0090] The permanent magnet 33 may be made of a rare earth material and may be described in terms of a longitudinal axis and a rectangular cross-sectional area having a major axis and a minor axis. Rare earth magnets are formed from alloys of rare earth materials, such as dysprosium reduction materials or another suitable material. Other rare earth materials may include neodymium and samarium. Alternatively, the permanent magnet 33 may be made of a non-rare earth material, such as ferrite, Alnico (aluminum-nickel-cobalt), FeCo (iron-cobalt), MnBi (manganese-bismuth), etc., or a combination thereof.
[0091] The annular enclosure 40 is made of carbon fiber or another material and encapsulates the outer peripheral surface 27 of the rotor assembly 20. As a non-limiting example, the annular enclosure 40 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.
[0092] External dimensions associated with the rotor assembly 20 include an outer diameter 29 . The outer diameter 29 is associated with the outer peripheral surface 27 of the rotor assembly 20 and the annular enclosure 40 , and is measured relative to the radial axis 13 .
[0093] In one embodiment, the stator 50 includes a plurality of stamped, ferrous disc-shaped laminations 52 arranged in a stack. Each disc-shaped lamination 52 is a disc-shaped device formed to have a uniform thickness and each defines a centrally located inner hole 51 formed to accommodate the outer diameter 29 of the rotor assembly 20 including the annular enclosure 40. Each disc-shaped lamination 52 also includes a plurality of radially oriented, inwardly protruding teeth 56. The disc-shaped laminations 52 are arranged in a stack so that the inner holes 51 are aligned and the inwardly protruding teeth 56 are aligned. The disc-shaped laminations 52 are assembled into a single device. The rotor opening 60 is formed by the concentrically aligned inner holes 51 of the plurality of disc-shaped laminations 52, and a plurality of longitudinally oriented slots 58 are formed between the aligned inwardly protruding teeth 56 of the plurality of disc-shaped laminations 52.
[0094] The slots 58 are configured to accommodate the electrical windings 54 arranged in a distributed electrical winding assembly 70, which in one embodiment is made of stranded wire. The stranded wire may be made of a suitable material, such as copper or aluminum. The internal dimensions associated with the stator 50 include an inner diameter, which defines the inner circumferential surface 28 of the stator 50. Alternatively, the electrical windings 54 may be arranged in a concentrated winding configuration.
[0095] The air gap 31 is formed between the outer circumferential surface 42 of the rotor assembly 20 (including the annular envelope 40 ) and the inner circumferential surface 28 of the stator 50 .
[0096] The distributed electric winding assembly 70 of the electric winding 54 in the stator 50 is preferably arranged to provide a rotating electric field arrangement structure, 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 such as the inverter 104. 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, which acts on the permanent magnets 33 embedded in the rotor assembly 20, thereby applying a torque to rotate the rotor assembly 20 around the rotor shaft 16 in the stator 50. Alternating current (AC) motors can generally be divided into AC induction motors and AC synchronous motors. In a rotating 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 becomes an electromagnet by exciting the magnet winding of the rotor assembly, and the rotor assembly rotates by applying a multi-phase alternating current to the stator. In applications where electrical power is derived from a DC power source 102 , multi-phase alternating current is generated by a power inverter 104 .
[0097] The electrical windings of the stator 50 are arranged to have a certain number of electrical phases and a certain number of turns of wire 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.
[0098] Specific geometric design parameters associated with the rotor assembly 20 and the stator 50 of the 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. Ranges for the first and second sets of geometric design parameters are selected to achieve motor operating parameters including: high drive cycle efficiency, for example, greater than 90% peak efficiency over a wide operating region; high torque density; wide peak power range; and a maximum speed of 21,000 rpm or more.
[0099] Figure 3 A first cross-sectional end view of a portion of an electric machine 10 including a cylindrical rotor assembly 20 and a stator 50 is schematically illustrated, wherein the rotor assembly 20 is coaxial with a rotor opening 60 formed in the stator 50. A single pole segment 30 of one of the first disc-shaped laminations 21 of the rotor assembly 20 is shown. In this embodiment, the pole segment 30 of the first disc-shaped lamination 21 is formed by a plurality of first cavities 32A arranged in a double V-shaped pattern and arranged in a nested V-shaped arrangement structure mirrored about a radial line 36. The plurality of first cavities 32A accommodate a corresponding plurality of permanent magnets 33. The permanent magnets 33 are prismatic elements having a long axis extending parallel to the longitudinal axis of the rotor shaft 16. In this embodiment, the first disc-shaped lamination 21 includes an inner portion 23 and a first outer portion 24A, which define and surround the plurality of first cavities 32A. The inner portion 23 is coupled to the first outer portion 24A via a bridge 38 formed on the outer peripheral surface 27 of the rotor assembly 20. In one embodiment, webs are formed in the first lamination 21 between adjacent ones of the first cavities 32A along the radial line 36. Alternatively and as shown, no webs are formed between adjacent ones of the first cavities 32A.
[0100] Figure 4A second cross-sectional end view of a portion of the electric machine 10 including a cylindrical rotor assembly 20 and a stator 50 is schematically illustrated, wherein the rotor assembly 20 is coaxial with a rotor opening 60 formed in the stator 50. A single pole segment 30 of one of the second disc-shaped laminations 22 of the rotor assembly 20 is shown. In this embodiment, the pole segment 30 of the second disc-shaped lamination 22 is formed by a plurality of second cavities 32B arranged in a double V-shaped pattern and arranged in a nested V-shaped arrangement structure mirrored around a radial line 36. The plurality of second cavities 32B accommodate a corresponding plurality of permanent magnets 33. The permanent magnets 33 are prismatic elements having a long axis extending parallel to the longitudinal axis of the rotor shaft 16. In this embodiment, the second disc-shaped lamination 22 includes an inner portion 23 and a second outer portion 24B, which define and surround the plurality of second cavities 32B. The inner portion 23 is coupled to the second outer portion 24B only via a web 35 formed along the radial line 36. No bridge is formed between the inner portion 23 and the second outer portion 24B. As such, when the second disc-shaped lamination 22 is in an unassembled state, the second outer portion 24B is fixed to the inner portion 23 in a cantilever position.
[0101] Figure 5 An embodiment of a portion of a rotor assembly 520 is illustrated, which is composed of a plurality of first disc-shaped laminations 21 and a plurality of second disc-shaped laminations 22. As described herein, the plurality of first disc-shaped laminations 21 and the plurality of second disc-shaped laminations 22 are staggered and arranged in a stack 510. In this embodiment, the first of the plurality of first disc-shaped laminations 22 is disposed on a first end 511 of the stack 510, and the second of the plurality of first disc-shaped laminations 21 is disposed on a second end 512 of the stack. In one embodiment, the third of the plurality of first disc-shaped laminations 21 is disposed in a middle portion 513 of the stack 510. The remainder of the stack 510 is filled by the plurality of second disc-shaped laminations 22. When the rotor assembly 20 is assembled, the second outer portion 24B of the second disc-shaped laminations 22 is fixed to the inner portion 23 by the encapsulation 40. Furthermore, because the plurality of first disc-shaped laminations 21 and the second disc-shaped laminations 22 are welded or otherwise bonded together in the axial direction during assembly, the second outer portion 24B of the disc-shaped laminations 22 is fixed to the inner portion 23 .
[0102] Figure 6Another embodiment of a portion of a rotor assembly 620 is illustrated, which is composed of a plurality of first disc-shaped laminations 21 and a plurality of second disc-shaped laminations 22. As described herein, the plurality of first disc-shaped laminations 21 and the plurality of second disc-shaped laminations 22 are staggered and arranged in a stack 610. In this embodiment, the first of the plurality of first disc-shaped laminations 22 is disposed on a first end 611 of the stack 510, and the second of the plurality of first disc-shaped laminations 21 is disposed on a second end 612 of the stack. In one embodiment, the third of the plurality of first disc-shaped laminations 21 is disposed in a middle portion 613 of the stack 610, the fourth of the plurality of first disc-shaped laminations 21 is disposed at a first quarter portion 614 of the stack 610, and the fifth of the plurality of first disc-shaped laminations 21 is disposed at a third quarter portion 615 of the stack 610. The remainder of the stack 610 is filled by the plurality of second disc-shaped laminations 22. The absence of a bridge at the end of the second cavity 32B containing the permanent magnet 33 means that there is less likelihood of flux leakage there. Likewise, when the rotor assembly 20 is assembled, the second outer portion 24B of the second disc-shaped laminations 22 is fixed to the inner portion 23 by the encapsulation member 40. In addition, because the plurality of first disc-shaped laminations 21 and second disc-shaped laminations 22 are welded or otherwise bonded together in the axial direction during assembly, the second outer portion 24B of the disc-shaped laminations 22 is fixed to the inner portion 23.
[0103] The concepts described herein provide an IPM motor comprising a rotor assembly arranged with a plurality of pole segments, each of which comprises one or more permanent magnets, wherein an encapsulation portion 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 not otherwise available.
[0104] Embodiments of electric machines described herein are configured to optimize operating parameters related to torque, speed, power, efficiency, packaging, mass, and other constraints.
[0105] The detailed description and 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 first disc-shaped laminations, a plurality of second disc-shaped laminations; Rotor shaft; Encapsulation; and a plurality of permanent magnets; wherein the plurality of first disc-shaped laminations and the plurality of second disc-shaped laminations are arranged in a stack on the rotor shaft; wherein each of the plurality of first disc-shaped laminations comprises a first inner portion and a plurality of first outer portions, the first inner portion and the plurality of first outer portions defining a plurality of first cavities; wherein the plurality of first outer portions are fixed to the first inner portion via a first web and a plurality of bridge portions; wherein each of the second plurality of disc-shaped laminations comprises a second inner portion and a plurality of second outer portions, the second inner portion and the plurality of second outer portions defining a plurality of second cavities; and Therein, the plurality of second outer parts are fixed to the second inner part via a plurality of second webs, and no bridge portion exists.
2. The rotor assembly according to claim 1, in, the first plurality of disk-shaped laminations are aligned with the second plurality of disk-shaped laminations such that the first plurality of cavities are aligned with the second plurality of cavities to form a plurality of axially disposed cavities; as well as Wherein, the plurality of axially arranged cavities define a plurality of radially arranged magnetic pole segments.
3. The rotor assembly according to claim 2, wherein: The plurality of permanent magnets are disposed in the plurality of axially disposed cavities.
4. The rotor assembly according to claim 2, wherein: The plurality of axially disposed cavities define a plurality of prisms arranged in a single V-shaped arrangement for each of the plurality of pole segments.
5. The rotor assembly according to claim 2, wherein: The plurality of axially disposed cavities define a plurality of prisms arranged in a double V-shaped arrangement for each of the plurality of pole segments.
6. The rotor assembly according to claim 2, wherein: The plurality of axially disposed cavities define a plurality of prisms arranged in a U-shaped arrangement for each of the plurality of pole segments.
7. The rotor assembly according to claim 1, wherein: The enclosure is arranged to encapsulate an outer surface of the rotor assembly defined by the first plurality of disc-shaped laminations and the second plurality of disc-shaped laminations.
8. The rotor assembly according to claim 7, wherein: The envelope includes a carbon fiber fabric encapsulating an outer peripheral surface of the rotor assembly.
9. The rotor assembly according to claim 1, wherein: The stacked arrangement of the first plurality of disk-shaped laminations and the second plurality of disk-shaped laminations on the rotor shaft includes: a first one of the first plurality of disk-shaped laminations being disposed on a first end of the stack, and a second one of the first plurality of disk-shaped laminations being disposed on a second end of the stack.
10. The rotor assembly of claim 9, comprising a third of said first plurality of disc-shaped laminations disposed in a middle portion of said stack.