# US 9,438,148 B2 · Motor drive device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,438,148 B2 - Document ID: US9438148B2 - Status: Granted - Kind: B2 - Application number: 14/206,129 - Filed: 2014-03-12 - Published: 2014-09-18 - Granted: 2016-09-06 - Earliest claimed: 2013-03-14 - Assignees: Hitachi Automotive Systems, Ltd. - Applicants: Hitachi Automotive Systems, Ltd. - Inventors: Tomoyasu Fuse; Tomonobu Koseki; Tomishige Yatsugi - Web page: https://patentgrep.com/patent/US9438148B2 ## CPC - H02P 6/12: Monitoring commutation; Providing indication of commutation failure - B62D 5/0484: {for reaction to failures, e.g. limp home} - B62D 5/0487: {detecting motor faults (B62D5/0496 takes precedence)} - H02H 7/0844: {Fail safe control, e.g. by comparing control signal and controlled current, isolating motor on commutation error} - H02P 27/06: using DC to AC converters or inverters (H02P27/05 takes precedence) - H02P 29/027: {the fault being an over-current} - H02P 31/00: Arrangements for regulating or controlling electric motors not provided for in groups H02P1/00 - H02P5/00, H02P7/00 or H02P21/00 - H02P29/00 - 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) - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) ## Abstract The present invention relates to a motor drive device having a drive circuit for driving a power supply relay and a phase relay providing a fail-safe function. The motor drive device includes: an inverter circuit for supplying electric power to an electric motor; a power supply relay provided on a power supply line for supplying electric power from a power supply to the inverter circuit; a phase relay provided on a drive line between the inverter circuit and the electric motor, and constituted by a semiconductor switching element; and a drive circuit connected to the phase relay and the power supply relay. The phase relay and the power supply relay share the same drive circuit, and the phase relay and the power supply relay are driven simultaneously by a drive signal output from the drive circuit. ## Claims ### Claim 1 A motor drive device comprising: an inverter circuit for supplying electric power to an electric motor; a power supply relay provided on a power supply line for supplying electric power from a power supply to the inverter circuit; a phase relay provided on a drive line between the inverter circuit and the electric motor, and constituted by a semiconductor switching element; a drive circuit connected to the phase relay and the power supply relay, for driving the phase relay and the power supply relay; a first control line connecting the drive circuit to the phase relay; a first surge-protection circuit provided at a position between the first control line and a motor-side line portion of the drive line connecting the electric motor to the phase relay, and configured to protect the phase relay from surge voltage; a first current reducing circuit configured to reduce a sneak current flowing from the electric motor into the first control line; a second control line connecting the drive circuit to the power supply relay; an electric charge accumulation element provided on an inverter-side line portion of the power supply line between the inverter circuit and the power supply relay, and configured to have a current supply capacity of the inverter circuit; a second surge-protection circuit connected at a position between the second control line and the inverter-side line portion; and a second current reducing circuit configured to reduce a sneak current flowing from the electric charge accumulation element into the second control line. ### Claim 2 (depends on 1) The motor drive device according to claim 1, wherein the first current reducing circuit is provided on the first control line. ### Claim 3 (depends on 1) The motor drive device according to claim 1, wherein the first current reducing circuit is provided at a position branched from the first control line so as to be in series with the first surge-protection circuit. ### Claim 4 (depends on 1) The motor drive device according to claim 1, wherein the first surge-protection circuit includes at least one of a zener diode and a diode, and the first current reducing circuit includes at least one of a zener diode, a diode, a resistor and a load element. ### Claim 5 (depends on 1) The motor drive device according to claim 1, wherein the semiconductor switching element constituting the phase relay includes an N-channel MOSFET. ### Claim 6 (depends on 1) The motor drive device according to claim 1, wherein the electric motor is a three-phase motor. ### Claim 7 (depends on 6) The motor drive device according to claim 6, wherein the inverter circuit includes an upstream side drive element and a downstream side drive element provided for each of drive lines of the three-phase motor so as to correspond to each phase. ### Claim 8 (depends on 7) The motor drive device according to claim 7, further comprising an inverter driver circuit supplied with a boosted power supply voltage and for controlling the inverter circuit. ### Claim 9 (depends on 8) The motor drive device according to claim 8, wherein the inverter driver circuit includes, for each phase, a high-side driver for controlling the upstream side drive element of the inverter circuit and a low-side driver for controlling the downstream side drive element of the inverter circuit. ### Claim 10 (depends on 1) The motor drive device according to claim 1, further comprising: a booster circuit for boosting the power supply voltage, and supplying the boosted voltage to the drive circuit so that the drive circuit supplies a control signal based on the boosted voltage to the phase relay and the power supply relay. ### Claim 11 (depends on 1) The motor drive device according to claim 1, further comprising: a microcomputer for controlling the drive circuit; and a power supply IC for supplying an operation power to the microcomputer based on the power supply voltage. ### Claim 12 (depends on 1) The motor drive device according to claim 1, wherein the power supply relay includes one of a mechanical relay and a semiconductor relay. ### Claim 13 A motor drive device comprising: an inverter circuit for supplying electric power to an electric motor; a power supply relay provided on a power supply line for supplying electric power from a power supply to the inverter circuit; a phase relay provided on a drive line between the inverter circuit and the electric motor, and constituted by a semiconductor switching element; a drive circuit connected to the phase relay and the power supply relay, for driving the phase relay and the power supply relay; a control line connecting the drive circuit to the power supply relay; an electric charge accumulation means provided on an inverter-side line portion of the power supply line between the inverter circuit and the power supply relay; a surge-protection means connected at a position between the control line and the inverter-side line portion; and a current reducing means for reducing a sneak current flowing from the electric charge accumulation means into the control line. ### Claim 14 A motor drive device comprising: an inverter circuit for supplying electric power to an electric motor; a power supply relay provided on a power supply line for supplying electric power from a power supply to the inverter circuit; a phase relay provided on a drive line between the inverter circuit and the electric motor, and constituted by a semiconductor switching element; a drive circuit connected to the phase relay and the power supply relay, for driving the phase relay and the power supply relay; a control line connecting the drive circuit to the power supply relay; an electric charge accumulation element provided on an inverter-side line portion of the power supply line between the inverter circuit and the power supply relay, and configured to have a current supply capacity of the inverter circuit; a surge-protection circuit connected at a position between the control line and the inverter-side line portion; and a current reducing circuit configured to reduce a sneak current flowing from the electric charge accumulation element into the control line. ### Claim 15 (depends on 14) The motor drive device according to claim 14, wherein the power supply relay is constituted by a semiconductor switching element. ### Claim 16 (depends on 14) The motor drive device according to claim 14, wherein the electric charge accumulation element is a smoothing capacitor provided at a position between the power supply line and a ground point. ### Claim 17 (depends on 14) The motor drive device according to claim 14, wherein the current reducing circuit includes at least one of a zener diode, a diode, a resistor and a load element, provided on the control line. ### Claim 18 (depends on 14) The motor drive device according to claim 14, wherein the current reducing circuit includes one of a zener diode and a diode, connected in series to the surge-protection circuit.