# US 12,214,829 B2 · Current detection device, motor control device, and electric power steering device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,214,829 B2 - Document ID: US12214829B2 - Status: Granted - Kind: B2 - Application number: 18/721,458 - Filed: 2022-12-08 - Published: 2024-12-19 - Granted: 2025-02-04 - Earliest claimed: 2022-02-18 - Assignees: Nsk Ltd. - Applicants: Nsk Ltd. - Inventors: Takayuki Kobayashi; Kyosho Uryu - Web page: https://patentgrep.com/patent/US12214829B2 ## CPC - B62D 5/046: {Controlling the motor} - H02M 1/0009: {Devices or circuits for detecting current in a converter} - B62D 5/0475: {Controlling other elements} - G01R 19/0092: {Measuring current only} - H02M 1/0025: {Arrangements for modifying reference values, feedback values or error values in the control loop of a converter} - H02M 7/53871: {with automatic control of output voltage or current} - H02P 6/28: Arrangements for controlling current (H02P6/10 takes precedence) - H02P 21/22: Current control, e.g. using a current control loop - H02P 27/08: with pulse width modulation - 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) - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract A current detection device includes a current detection unit configured to detect current flowing through a switching element of a lower-side arm; a correction value calculation unit configured to calculate an offset correction value, based on a detection value of the current detected by the current detection unit in a period during which the switching element off during PWM control, and to hold and update the calculated offset correction value; and a correction unit configured to correct, by the offset correction value held by the correction value calculation unit, the detection value of the current detected by the current detection unit in a period during which the switching element is on. The correction value calculation unit is configured to not update the offset correction value in a case where a duty ratio of the PWM control is equal to or less than a duty ratio lower limit value. ## Claims ### Claim 1 A current detection device comprising: a current detection unit configured to detect current flowing through a switching element of one arm of either an upper-side arm or a lower-side arm of a multiphase inverter on which PWM control is executed, based on a voltage drop of a resistor element connected in series to the switching element; a correction value calculation unit configured to calculate an offset correction value, based on a detection value of the current detected by the current detection unit in a period during which the switching element is off during the PWM control, and to hold and update the calculated offset correction value; and a correction unit configured to correct, by the offset correction value held by the correction value calculation unit, the detection value of the current detected by the current detection unit in a period during which the switching element is on, wherein the correction value calculation unit is configured to not update the offset correction value in a case where the switching element is the switching element of the lower-side arm and a duty ratio of the PWM control is equal to or less than a duty ratio lower limit value, or in a case where the switching element is the switching element of the upper-side arm and the duty ratio is equal to or greater than a duty ratio upper limit value, and in a case where the switching element is the switching element of the lower-side arm and the duty ratio is equal to or less than the duty ratio lower limit value in at least one phase of phases of the multiphase inverter, or in a case where the switching element is the switching element of the upper-side arm and the duty ratio is equal to or greater than the duty ratio upper limit value in at least one phase of the phases of the multiphase inverter, the correction value calculation unit is configured to not update the offset correction value in another phase of the phases of the multiphase inverter. ### Claim 2 (depends on 1) The current detection device according to claim 1, wherein the correction value calculation unit is configured to calculate, as the offset correction value, an average of detection values of current detected by the current detection unit in a period of a predetermined length during which the switching element is off. ### Claim 3 (depends on 1) The current detection device according to claim 1, wherein in a case where the detection value of the current detected by the current detection unit in the period during which the switching element is off exceeds an upper limit value, the correction value calculation unit is configured to not update the offset correction value by the detection value exceeding the upper limit value. ### Claim 4 (depends on 3) The current detection device according to claim 3, wherein in a case where the detection value of the current detected by the current detection unit in the period during which the switching element is off exceeds the upper limit value in one phase of the phases of the multiphase inverter, and the detection value of the current detected by the current detection unit in the period during which the switching element is off does not exceed the upper limit value in another phase of the phases of the multiphase inverter, the correction value calculation unit is configured to update the offset correction value in the another phase. ### Claim 5 (depends on 1) A motor control device comprising: a multiphase inverter including a switching element; the current detection device according to claim 1, the current detection device being configured to detect current flowing through the switching element; and a controller configured to control the multiphase inverter, based on a detection current value by the current detection device. ### Claim 6 (depends on 5) An electric power steering device comprising: the motor control device according to claim 5; and a multiphase motor configured to be controlled by the motor control device, wherein steering assistance force is given to a steering system of a vehicle by the multiphase motor. ### Claim 7 A current detection device comprising: a current detection unit configured to detect current flowing through a switching element of one arm of either an upper-side arm or a lower-side arm of a multiphase inverter on which PWM control is executed, based on a voltage drop of a resistor element connected in series to the switching element; a correction value calculation unit configured to calculate an offset correction value, based on a detection value of the current detected by the current detection unit in a period during which the switching element is off during the PWM control, and to hold and update the calculated offset correction value; and a correction unit configured to correct, by the offset correction value held by the correction value calculation unit, the detection value of the current detected by the current detection unit in a period during which the switching element is on, wherein the correction value calculation unit is configured to not update the offset correction value in a case where the switching element is the switching element of the lower-side arm and a duty ratio of the PWM control is equal to or less than a duty ratio lower limit value, or in a case where the switching element is the switching element of the upper-side arm and the duty ratio is equal to or greater than a duty ratio upper limit value, and in a case where the detection value of the current detected by the current detection unit in the period during which the switching element is off exceeds an upper limit value, the correction value calculation unit is configured to not update the offset correction value by the detection value exceeding the upper limit value. ### Claim 8 (depends on 7) The current detection device according to claim 7, wherein in a case where the detection value of the current detected by the current detection unit in the period during which the switching element is off exceeds the upper limit value in one phase of the phases of the multiphase inverter, and the detection value of the current detected by the current detection unit in the period during which the switching element is off does not exceed the upper limit value in another phase of the phases of the multiphase inverter, the correction value calculation unit is configured to update the offset correction value in the another phase. ### Claim 9 (depends on 7) A motor control device comprising: a multiphase inverter including a switching element; the current detection device according to claim 7, the current detection device being configured to detect current flowing through the switching element; and a controller configured to control the multiphase inverter, based on a detection current value by the current detection device. ### Claim 10 (depends on 9) An electric power steering device comprising: the motor control device according to claim 9; and a multiphase motor configured to be controlled by the motor control device, wherein steering assistance force is given to a steering system of a vehicle by the multiphase motor.