# US 10,374,531 B2 · Motor control device and electric power steering system using said motor drive circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,374,531 B2 - Document ID: US10374531B2 - Status: Granted - Kind: B2 - Application number: 15/317,289 - Filed: 2015-05-11 - Published: 2017-04-27 - Granted: 2019-08-06 - Earliest claimed: 2014-06-30 - Assignees: Hitachi Automotive Systems, Ltd. - Applicants: Hitachi Automotive Systems, Ltd. - Inventors: Nobuyasu Kanekawa; Ryoichi Kobayashi; Tomonobu Koseki; Takuro Kanazawa - Web page: https://patentgrep.com/patent/US10374531B2 ## CPC - H02P 6/10: Arrangements for controlling torque ripple, e.g. providing reduced torque ripple - B62D 5/046: {Controlling the motor} - H02P 21/22: Current control, e.g. using a current control loop - H02P 21/50: {Vector control arrangements or methods not otherwise provided for in H02P21/00- H02P21/36} - H02P 25/22: Multiple windings; Windings for more than three phases - H02P 27/08: with pulse width modulation - H02P 27/085: {wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency} - H02P 29/60: Controlling or determining the temperature of the motor or of the drive (H02P29/02 takes precedence) - B62D 5/04: electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - 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) ## Abstract The purpose of the present invention is not only to reduce ripple current but also to improve operation efficiency by reducing heat generation. When n is defined as an integer of 2 or more, a motor control device of the present invention drives n sets of windings by n sets of inverters. The motor control device is characterized in that when said n sets of inverters output high power, at least one or more of said n sets of inverters are set to have an output duty cycle of 100%. ## Claims ### Claim 1 A motor control device for a motor, comprising: a set of n coils driven by a set of n inverters, n being defined as an integer of 2 or more; and two redundant control devices, each of the redundant control devices being configured to individually control the motor, such that upon failure of one of the two redundant control devices, the other of the two redundant control devices is configured to continue controlling the motor, wherein at least one inverter in the set of n inverters has an output duty cycle of 100% when output of the set of n inverters is higher than a given value, the at least one inverter switching another inverter of the set of n inverters with a predetermined frequency, and the motor device is configured to operate at a given cycle, the given cycle being 1/(the predetermined frequency), the given cycle is less than a thermal time constant of each of the at least one inverter and the another inverter. ### Claim 2 (depends on 1) The motor control device according to claim 1, further comprising three phase to two phase converters, each three phase to two phase converter being directly interposed between the motor and one of the set of n inverters. ### Claim 3 (depends on 2) The motor control device according to claim 2, wherein m is defined as an integer equal to or less than the n, an output duty cycle of m inverters is set to 100% when a target value of a total duty cycle of output of the set of n inverters is m×100/n % or more. ### Claim 4 (depends on 2) The motor control device according to claim 2, wherein the at least one inverter has the output duty cycle of 100% is switched with the predetermined frequency. ### Claim 5 (depends on 4) The motor control device according to claim 4, wherein the set of n inverters has an inverter having the output duty cycle set at 100%, the inverter being switched at the predetermined frequency. ### Claim 6 (depends on 3) The motor control device according to claim 3, wherein duty cycles of output of the set of n inverters are differentiable by the total duty cycle. ### Claim 7 (depends on 3) The motor control device according to claim 3, wherein a first derivative of the total duty cycle of the duty cycles of output of the set of n inverters is zero or more. ### Claim 8 (depends on 2) The motor control device according to claim 2, wherein when duty cycles of output of at least two inverters are less than 100%, switching timing of output of the at least two inverters has a phase difference. ### Claim 9 (depends on 2) The motor control device according to claim 2, further comprising a slope control function that controls a switching waveform of an output waveform to be a moderate gradient when all of the set of n inverters are normal, and controls the switching waveform of the output waveform of a remaining inverter to be a steep gradient when failure occurs in the set of n inverters. ### Claim 10 An electric power steering system comprising: a set of n coils driven by a set of n inverters, n being defined as an integer of 2 or more; a steering wheel; a rotation shaft attached to the steering wheel; a torque sensor attached to the rotation shaft; a steering mechanism; a motor; and two redundant control devices, each of the redundant control devices being configured to individually control the motor, such that upon failure of one of the two redundant control devices, the other of the two redundant control devices is configured to continue controlling the motor, wherein the steering mechanism is steered by the rotation shaft, the steering mechanism or the rotation shaft has steering force assisted by the motor, the motor control device controls the motor, at least one inverter in the set of n inverters has an output duty cycle of 100% when output of the set of n inverters is higher than a given value, the at least one inverter switching another inverter of the set of n inverters with a predetermined frequency, the motor device is configured to operate at a given cycle, the given cycle being 1/(the predetermined frequency), the given cycle is less than a thermal time constant of each of the at least one inverter and the another inverter. ### Claim 11 (depends on 10) The electronic power steering system according to claim 10, further comprising three phase to two phase converters, each three phase to two phase converter being directly interposed between the motor and one of the set of n inverters.