# US 10,320,254 B2 · Permanent magnet motor and electric power steering apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,320,254 B2 - Document ID: US10320254B2 - Status: Granted - Kind: B2 - Application number: 14/783,104 - Filed: 2013-07-22 - Published: 2016-02-04 - Granted: 2019-06-11 - Earliest claimed: 2013-07-22 - Assignees: Mitsubishi Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Masatsugu Nakano; Yu Hirotani; Yuji Takizawa; Satoru Akutsu; Toyoaki Udo - Web page: https://patentgrep.com/patent/US10320254B2 ## CPC - H02K 3/28: Layout of windings or of connections between windings (windings for pole-changing H02K17/06, H02K17/14, H02K19/12, H02K19/32) - H02K 1/16: Stator cores with slots for windings - H02K 1/2706: Inner rotors - H02K 1/2746: the rotor consisting of magnets arranged with the same polarity, e.g. consequent pole type - H02K 1/2781: Magnets shaped to vary the mechanical air gap between the magnets and the stator - H02K 7/14: Structural association with mechanical loads, e.g. with hand-held machine tools or fans (with fan or impeller for cooling the machine H02K9/06) - H02K 11/0094: {Structural association with other electrical or electronic devices} - H02K 11/215: Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements - H02K 11/33: Drive circuits, e.g. power electronics (H02K11/38 takes precedence) - H02K 29/03: with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems - H02K 29/08: using magnetic effect devices, e.g. Hall-plates, magneto-resistors (H02K29/12 takes precedence) - B62D 5/04: electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear - H02K 1/165: {Shape, form or location of the slots} - H02K 1/276: Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] - H02K 1/2773: {consisting of tangentially magnetized radial magnets} - H02K 2201/03: Machines characterised by aspects of the air-gap between rotor and stator - H02K 2213/03: Machines characterised by numerical values, ranges, mathematical expressions or similar information - H02P 25/22: Multiple windings; Windings for more than three phases - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) - B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M) - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract A permanent magnet motor is provided in which, in flanges each provided in a plurality of teeth, lateral side portions of the flanges oppose to lateral side portions the flanges being provided in adjacent teeth and protruding in a circumferential direction of a stator core; when a height in the lateral side portion of the flanges in a radial direction of the stator core is defined as “h,” and the length of a magnetic air gap is defined as “g,” the relationship “1≤h/g≤2” is held; and also, when a circumferential distance between opposing faces of the flanges being adjacent to each other is defined as “a,” the relationship “a/g≥0.2” is satisfied. ## Claims ### Claim 1 A permanent magnet motor, comprising: a rotor including a rotor core fixed on a motor shaft, and permanent magnets fixed on the rotor core; and a stator including a stator core, whose inner circumferential face opposes to an outer circumferential face of the rotor by means of a magnetic air gap, having a plurality of slots for accommodating armature windings, and a plurality of teeth, the permanent magnet motor characterized in that: the armature windings are constituted of a plurality of groups of multi-phase windings; the plurality of groups of multi-phase windings is supplied with electric power from individual inverters in every one of respective groups; the plurality of teeth each include respective flanges; the flanges each have a lateral side portion thereof opposing to a lateral side portion of a flange being provided in the teeth adjacent to each other and protruding in a circumferential direction of the stator core; when a height in the lateral side portion of the flanges in a radial direction of the stator core is defined as h, and a length of the magnetic air gap is defined as g, relationship 1≤h/g≤2 is held; and also, when a circumferential distance between opposing faces of the flanges being adjacent to each other is defined as a, relationship a/g≥0.2 is satisfied, wherein, when a width of portions of the teeth, existing from the flanges on an outer radial side of the stator, where a circumferential width of the stator becomes a smallest is defined as w, a maximum outer diameter of the rotor core is defined as Rout, and the number of slots is defined as Ns, the width w of the portions of the teeth satisfies a relationship 0.4×2π(Rout+g+h)/Ns≤w≤0.5×2π(Rout+g+h)/Ns. ### Claim 2 (depends on 1) The permanent magnet motor as set forth in claim 1, wherein the armature windings are constituted of two groups of three-phase armature windings made of a first armature winding and a second armature winding; the first armature winding is supplied with an electric current from a first inverter circuit; the second armature winding is supplied with an electric current from a second inverter circuit; the first armature winding includes a phase-U1 winding, a phase-V1 winding and a phase-W1 winding; the second armature winding includes a phase-U2 winding, a phase-V2 winding and a phase-W2 winding; the phase-U1 winding and the phase-U2 winding are side by side accommodated in the slots adjacent to each other; the phase-V1 winding and the phase-V2 winding are side by side accommodated in the slots adjacent to each other; the phase-W1 winding and the phase-W2 winding are side by side accommodated in the slots adjacent to each other; and electric currents each flowing through the first armature winding and the second armature winding mutually have a phase difference of an electrical angle of twenty degrees or more, and an electrical angle of forty degrees or less. ### Claim 3 (depends on 1) The permanent magnet motor as set forth in claim 1, wherein the lateral side portion of the flanges includes a curved face portion on either one of a portion positioned on an inner radial side of the stator, and a portion positioned on an outer radial side thereof. ### Claim 4 (depends on 1) The permanent magnet motor as set forth in claim 1, wherein the lateral side portion of the flanges includes curved face portions on both a portion positioned on an inner radial side of the stator, and a portion positioned on an outer radial side thereof. ### Claim 5 (depends on 1) The permanent magnet motor as set forth in claim 1, wherein the lateral side portion of the flanges each provided on adjacent teeth and opposing to each other is formed to be side by side in parallel with the other lateral side portion. ### Claim 6 (depends on 1) The permanent magnet motor as set forth in claim 1, wherein the permanent magnets are placed on a surface of the rotor core opposing to the stator core; the rotor core includes protrusion portions provided in portions where the permanent magnets are not placed; and a gap is provided between the protrusion portions and the permanent magnets. ### Claim 7 (depends on 1) The permanent magnet motor as set forth in claim 1, wherein the permanent magnets are placed in hole-portions formed in the rotor core. ### Claim 8 (depends on 1) The permanent magnet motor as set forth in claim 1, wherein the permanent magnets are formed such that a length thereof in a radial direction of the rotor is larger in comparison with a length in a circumferential direction thereof; directions of magnetization of the permanent magnets are in such orientations that faces of the adjacent permanent magnets opposing to each other mutually form an identical magnetic pole; the rotor core interposes between the adjacent permanent magnets; the rotor core has curved-plane portions on faces opposing to the stator core, and also includes non-magnetic portions provided at positions contacting with end faces toward radially inner sides of the permanent magnets; and the curved-plane portions each are formed in a protrusion shape so that, in a middle portion between the adjacent permanent magnets, a length of the magnetic air gap is smaller than that of another portion. ### Claim 9 (depends on 1) An electric power steering apparatus on which a permanent magnet motor as set forth in claim 1 is mounted, and torque is produced by the permanent magnet motor so as to assist steering of a driver, the electric power steering apparatus characterized in that the permanent magnet motor is placed in such a direction that the motor shaft is in parallel with an extending direction of a rack shaft for driving a steering wheel of a wheeled vehicle. ### Claim 10 A permanent magnet motor, comprising: a rotor including a rotor core fixed on a motor shaft, and permanent magnets fixed on the rotor core; and a stator including a stator core, whose inner circumferential face opposes to an outer circumferential face of the rotor by means of a magnetic air gap, having a plurality of slots for accommodating armature windings, and a plurality of teeth, the permanent magnet motor characterized in that: the armature windings are constituted of a plurality of groups of multi-phase windings; the plurality of groups of multi-phase windings is supplied with electric power from individual inverters in every one of respective groups; the plurality of teeth each include respective flanges; the flanges each have a lateral side portion thereof opposing to a lateral side portion of a flange being provided in the teeth adjacent to each other and protruding in a circumferential direction of the stator core; when a height in the lateral side portion of the flanges in a radial direction of the stator core is defined as h, and a length of the magnetic air gap is defined as g, relationship 1≤h/g≤2 is held; and also, when a circumferential distance between opposing faces of the flanges being adjacent to each other is defined as a, relationship a/g≥0.2 is satisfied, wherein, when a circumferential width of the slots corresponding to a portion of the teeth, existing from the flanges on an outer radial side of the stator, where the circumferential width of the stator becomes a smallest is defined as S1, a maximum outer diameter of the rotor core is defined as Rout, and the number of slots is defined as Ns, the width S1 of the slots satisfies a relationship 0.5×2π(Rout+g+h)/Ns≤S1≤0.6×2π(Rout+g+h)/Ns, and also the circumferential width of the slots gradually increases in accordance with a position on an outer radial side of the stator, and is maximized on a back-portion of the slots or a back-portion's vicinity thereof. ### Claim 11 (depends on 10) The permanent magnet motor as set forth in claim 10, wherein the permanent magnets are placed on a surface of the rotor core opposing to the stator core; the rotor core includes protrusion portions provided in portions where the permanent magnets are not placed; and a gap is provided between the protrusion portions and the permanent magnets. ### Claim 12 (depends on 10) The permanent magnet motor as set forth in claim 10, wherein the permanent magnets are placed in hole-portions formed in the rotor core. ### Claim 13 (depends on 10) The permanent magnet motor as set forth in a claim 10, wherein the permanent magnets are formed such that a length thereof in a radial direction of the rotor is larger in comparison with a length in a circumferential direction thereof; directions of magnetization of the permanent magnets are in such orientations that faces of the adjacent permanent magnets opposing to each other mutually form an identical magnetic pole; the rotor core interposes between the adjacent permanent magnets; the rotor core has curved-plane portions on faces opposing to the stator core, and also includes non-magnetic portions provided at positions contacting with end faces toward radially inner sides of the permanent magnets; and the curved-plane portions each are formed in a protrusion shape so that, in a middle portion between the adjacent permanent magnets, a length of the magnetic air gap is smaller than that of another portion. ### Claim 14 (depends on 10) An electric power steering apparatus on which a permanent magnet motor as set forth in claim 10 is mounted, and torque is produced by the permanent magnet motor so as to assist steering of a driver, the electric power steering apparatus characterized in that the permanent magnet motor is placed in such a direction that the motor shaft is in parallel with an extending direction of a rack shaft for driving a steering wheel of a wheeled vehicle.