# US 2023/0054469 A1 · Calibration method for rotation angle sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2023/0054469 A1 - Document ID: US20230054469A1 - Status: Published application - Kind: A1 - Application number: 17/800,182 - Filed: 2021-02-05 - Published: 2023-02-23 - Earliest claimed: 2020-02-18 - Assignees: Hitachi Astemo, Ltd. - Applicants: Hitachi Astemo, Ltd. - Inventors: Huajun LIU; Masaki KASHIMA - Web page: https://patentgrep.com/patent/US20230054469A1 ## CPC - G01D 5/145: {influenced by the relative movement between the Hall device and magnetic fields (see G01R33/06)} - H02K 11/215: Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements - G01D 18/008: {with calibration coefficients stored in memory} - H02P 21/18: Estimation of position or speed - B62D 5/046: {Controlling the motor} - H02P 6/16: Circuit arrangements for detecting position - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) - 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 A motor shaft is rotated to a predetermined rotation stop position by excitation of two-phase coils out of three-phase coils of a stator coil, and a detection value of a rotation angle sensor at the rotation stop position is acquired. Further, a sensor-error correction parameter for correcting a detection value of the rotation angle sensor in drive control of an electric motor is generated from the acquired detection value of the rotation angle sensor. With this configuration, in rotating a motor rotor to the predetermined rotation stop position, two coils out of the three-phase coils of the stator coil are excited. By sequentially changing the coils being excited, it is possible to cause the motor rotor to stop accurately at the predetermined rotation stop position. ## Claims ### Claim 1 A calibration method for a rotation angle sensor for an electric motor, the electric motor including: a stator coil including coils of a U phase, a V phase, and a W phase; a motor rotor to be rotated by excitation of the stator coil; a motor shaft to be rotated in conjunction with the motor rotor; and a rotation angle sensor configured to detect a rotation position of the motor shaft, the method comprising: an excitation step including the steps of: exciting a predetermined single-phase coil or a first pair of coils including predetermined two-phase coils out of the coils of the stator coil, to thereby rotate the motor shaft to a first rotation stop position; and exciting a coil different from the predetermined single-phase coil or a second pair of coils different from the first pair of coils, to thereby rotate the motor shaft to a second rotation stop position; a rotation-position detection step including the steps of: acquiring a detection value of the rotation angle sensor at the first rotation stop position; and acquiring a detection value of the rotation angle sensor at the second rotation stop position; and a sensor-error correction parameter generation step of generating a sensor-error correction parameter for correcting a detection value of the rotation angle sensor in drive control of the electric motor, from the detection values of the rotation angle sensor acquired in the rotation-position detection step. ### Claim 2 (depends on 1) The calibration method for a rotation angle sensor according to claim 1, wherein the sensor-error correction parameter generation step includes generating the sensor-error correction parameter by substitution of the detection values of the rotation angle sensor into a sensor-error correction parameter calculation expression. ### Claim 3 (depends on 2) The calibration method for a rotation angle sensor according to claim 2, wherein the sensor-error correction parameter calculation expression is an arithmetic expression including an amplitude and a phase as variables. ### Claim 4 (depends on 1) The calibration method for a rotation angle sensor according to claim 1, wherein the excitation step further includes: a clockwise excitation step of exciting the stator coil so that the motor shaft is rotated clockwise; and a counterclockwise excitation step of exciting the stator coil so that the motor shaft is rotated counterclockwise, wherein the rotation-position detection step further includes the steps of: acquiring detection values of the rotation angle sensor for rotation of the motor shaft to the first rotation stop position and to the second rotation stop position in the clockwise excitation step; and acquiring detection values of the rotation angle sensor for rotation of the motor shaft to the first rotation stop position and to the second rotation stop position in the counterclockwise excitation step, wherein the sensor-error correction parameter generation step includes using an average value of the detection value of the rotation angle sensor for rotation of the motor shaft to the first rotation stop position in the clockwise excitation step and the detection value of the rotation angle sensor for rotation of the motor shaft to the first rotation stop position in the counterclockwise excitation step as the detection value of the rotation angle sensor, and wherein the sensor-error correction parameter generation step includes using an average value of the detection value of the rotation angle sensor for rotation of the motor shaft to the second rotation stop position in the clockwise excitation step and the detection value of the rotation angle sensor for rotation of the motor shaft to the second rotation stop position in the counterclockwise excitation step as the detection value of the rotation angle sensor. ### Claim 5 (depends on 1) The calibration method for a rotation angle sensor according to claim 1, wherein the electric motor includes N slots, wherein the excitation step is a step of rotating the motor shaft to N rotation stop positions or to twice as many rotation stop positions as N, and wherein the rotation-position detection step is a step of acquiring detection values of the rotation angle sensor at the N rotation stop positions or at the twice as many rotation stop positions as N. ### Claim 6 (depends on 5) The calibration method for a rotation angle sensor according to claim 5, wherein the electric motor includes 12 slots, wherein the excitation step is a step of rotating the motor shaft to 24 rotation stop positions, and wherein the rotation-position detection step is a step of acquiring detection values of the rotation angle sensor at the 24 rotation stop positions. ### Claim 7 (depends on 1) The calibration method for a rotation angle sensor according to claim 1, wherein the electric motor is configured to apply steering force to a steering apparatus of an automobile, and further includes a motor housing and a bearing, wherein the rotation angle sensor includes a sensor magnet and a magnetic sensor, wherein the sensor magnet is provided onto the motor shaft, wherein the magnetic sensor is configured to detect a change in magnetic field generated by the sensor magnet, and wherein the stator coil, the motor rotor, the motor shaft, and the bearing are installed in the motor housing, and the excitation step and the rotation-position detection step are performed under a state in which the sensor magnet is installed onto the motor shaft. ### Claim 8 (depends on 7) The calibration method for a rotation angle sensor according to claim 7, wherein the steering apparatus is applied with rotational force of the electric motor via a deceleration mechanism, and wherein the excitation step and the rotation-position detection step are performed under a state in which the electric motor is disconnected from the deceleration mechanism. ### Claim 9 (depends on 1) The calibration method for a rotation angle sensor according to claim 1, wherein the rotation angle sensor includes a first rotation angle sensor and a second rotation angle sensor, and wherein the rotation-position detection step further includes the steps of: acquiring a detection value of the first rotation angle sensor and a detection value of the second rotation angle sensor at the first rotation stop position when the motor shaft is rotated to the first rotation stop position in the excitation step; and acquiring a detection value of the first rotation angle sensor and a detection value of the second rotation angle sensor at the second rotation stop position when the motor shaft is rotated to the second rotation stop position in the excitation step.