# US 2017/0282966 A1 · 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 2017/0282966 A1 - Document ID: US20170282966A1 - Status: Published application - Kind: A1 - Application number: 15/519,581 - Filed: 2015-12-25 - Published: 2017-10-05 - Earliest claimed: 2014-12-25 - Assignees: Nsk Ltd. - Applicants: Nsk Ltd. - Inventors: Toshihiro FUKUDA; Yasuhide NOMURA; Tamotsu OUMI - Web page: https://patentgrep.com/patent/US20170282966A1 ## CPC - B62D 5/046: {Controlling the motor} - B62D 5/0463: {calculating assisting torque from the motor based on driver input} - B62D 5/0466: {for returning the steering wheel to neutral position} - H02P 25/22: Multiple windings; Windings for more than three phases - B62D 5/0403: {characterised by constructional features, e.g. common housing for motor and gear box} - 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 An electric power steering apparatus that driving-controls a motor via inverters based on a current command value, and applies an assist force by the motor to a steering system, includes multi-system driving systems with the inverters for respective system-windings of the motor which is a multi-system motor, wherein respective multi-system current command value characteristics against a steering torque are applied so as to be disproportionate for left and right steering, to the respective multi-system driving systems, and an assist-control is performed in response to the individual current command value characteristics. ## Claims ### Claim 1 An electric power steering apparatus that driving-controls a motor via inverters based on a current command value which is a steering command, and applies an assist force by means of said motor to a steering system of a vehicle, comprising: multi-system driving systems with said inverters for respective system-windings of said motor which is a multi-system motor, wherein said electric power steering apparatus applies respective multi-system current command value characteristics against a steering torque so as to be disproportionate to said respective multi-system driving systems at a left steering maneuver and a right steering maneuver, and assist-controls in response to said individual current command value characteristics for said multi-system driving systems. ### Claim 2 (depends on 1) The electric power steering apparatus according to claim 1, wherein said multi-system current command value characteristics have offsets near a handle center and have characteristics that a difference of offset amounts is larger as an absolute value of said steering torque becomes larger. ### Claim 3 (depends on 2) The electric power steering apparatus according to claim 2, wherein a degree of said offset is changeable characteristic. ### Claim 4 (depends on 3) The electric power steering apparatus according to claim 3, wherein said changeable characteristic is a vehicle speed sensitive-characteristic. ### Claim 5 (depends on 4) The electric power steering apparatus according to claim 4, wherein said vehicle speed sensitive-characteristic has a smaller offset near said handle center, and has a larger or smaller degree of a difference of said offset amounts as said vehicle speed becomes higher. ### Claim 6 (depends on 1) The electric power steering apparatus according to claim 1, wherein all of said multi-system motor, said multi-system driving systems and said multi-system current command value characteristics are at least dual-system. ### Claim 7 (depends on 6) The electric power steering apparatus according to claim 6, wherein said motor has a dual-system windings of a star-connection. ### Claim 8 (depends on 6) The electric power steering apparatus according to claim 6, wherein said motor has a dual-system windings of a delta-connection. ### Claim 9 (depends on 1) The electric power steering apparatus according to claim 1, wherein all of said multi-system motor, said multi-system driving systems and said multi-system current command value characteristics are dual-system, one part of a dual-system motor is used to one direction region by a one-direction current command value, and other part of said dual-system motor is used to other direction region by an other-direction current command value. ### Claim 10 (depends on 9) The electric power steering apparatus according to claim 9, wherein said one-direction current command value has an offset 1 and said other-direction current command value has an offset 2 near a handle center. ### Claim 11 (depends on 10) The electric power steering apparatus according to claim 10, wherein said one-direction current command value increases as said steering torque becomes larger in said one direction region and said other-direction current command value increases as said steering torque becomes larger in said other direction region. ### Claim 12 (depends on 11) The electric power steering apparatus according to claim 11, wherein varying characteristics of said one-direction current command value and said other-direction current command value are changeable. ### Claim 13 (depends on 10) The electric power steering apparatus according to claim 10, wherein said offset 1 is equal to said offset 2. ### Claim 14 (depends on 10) The electric power steering apparatus according to claim 10, wherein said offset 1 is different from said offset 2. ### Claim 15 (depends on 13) The electric power steering apparatus according to claim 13, wherein said offset 1 and said offset 2 varies in response to said vehicle speed. ### Claim 16 An electric power steering apparatus that driving-controls a motor via inverters based on a current command value which is a steering command, and applies an assist force by means of said motor to a steering mechanism of a vehicle; wherein said motor is at least dual-system motor and said inverters are provided for respective system-windings of said motor, wherein one part of said at least dual-system motor is used to one direction region by a one-direction current command value and other part of said at least dual-system motor is used to other direction region by an other-direction current command value, and wherein said one-direction current command value has an offset 1 and said other-direction current command value has an offset 2 near a handle center, and said offset 1 and said offset 2 are calculated based on a travel state of said vehicle and an acting force applied to said steering mechanism. ### Claim 17 (depends on 16) The electric power steering apparatus according to claim 16, wherein said offset 1 and said offset 2 vary in response to said acting force when said travel state of said vehicle is a straight-travel state. ### Claim 18 (depends on 17) The electric power steering apparatus according to claim 17, wherein in said straight-travel state, said offset 1 increases as said acting force becomes larger in said one direction region, and said offset 2 increases as said acting force becomes larger in said other direction region. ### Claim 19 (depends on 17) The electric power steering apparatus according to claim 17, wherein in said straight-travel state, said offset 2 decreases as said acting force becomes larger in said one direction region, and said offset 1 decreases as said acting force becomes larger in said other direction region. ### Claim 20 (depends on 17) The electric power steering apparatus according to claim 17, wherein said offset 1 and said offset 2 respectively return to initial values based on a rotational angle and said acting force of said steering mechanism when said vehicle deviates from said straight-travel state. ### Claim 21 (depends on 17) The electric power steering apparatus according to claim 17, wherein said offset 1 and said offset 2 gradually vary and gradually return to said respective initial values. ### Claim 22 (depends on 16) The electric power steering apparatus according to claim 16, wherein varying characteristics of said one-direction current command value and said other-direction current command value are changeable. ### Claim 23 (depends on 16) The electric power steering apparatus according to claim 16, wherein said acting force is a self-aligning torque or a steering torque.