# US 9,038,764 B2 · Electrical power steering apparatus

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- Number: US 9,038,764 B2
- Document ID: US9038764B2
- Status: Granted
- Kind: B2
- Application number: 14/100,488
- Filed: 2013-12-09
- Published: 2014-06-26
- Granted: 2015-05-26
- Earliest claimed: 2012-12-20
- Assignees: Jtekt Corporation
- Applicants: Jtekt Corporation
- Inventors: Motoo Nakai
- Web page: https://patentgrep.com/patent/US9038764B2

## CPC

- B60L 3/0046: {relating to electric energy storage systems, e.g. batteries or capacitors}
- B60L 1/003: {to auxiliary motors, e.g. for pumps, compressors}
- B60L 3/0007: {Measures or means for preventing or attenuating collisions}
- B60L 3/0069: {relating to the isolation, e.g. ground fault or leak current}
- B60L 3/04: Cutting off the power supply under fault conditions (protective devices and circuit arrangements in general H01H; H02H)
- B60L 15/20: for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
- B60L 50/51: characterised by AC-motors
- B60L 58/20: having different nominal voltages
- B62D 5/046: {Controlling the motor}
- B62D 5/0475: {Controlling other elements}
- B62D 5/0481: {monitoring the steering system, e.g. failures}
- B60L 2210/12: Buck converters
- B60L 2240/12: Speed
- B60L 2240/14: Acceleration
- B60L 2240/24: Steering angle
- B60L 2240/421: Speed
- B60L 2240/423: Torque
- Y02T 10/64: Electric machine technologies in electromobility
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- Y02T 10/72: Electric energy management in electromobility
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- 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)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A motor control circuit includes a power relay, a converter division, a smoothing condenser, a control circuit and a motor drive circuit, and is connected to a battery as high voltage power and to an electrical motor. The battery is connected with a driving battery having the high voltage such as 288V etc. A step down circuit reduces the high voltage to a low voltage such as 36V etc., charges a low voltage charge device and supplies drive power to the motor drive circuit. When the vehicle collision is occurred, the control circuit detects the collision by a value of detected acceleration, a power change relay is turned on to change to the power source from the low voltage charge device after voltage of the smoothing condenser is reduced, thereby connecting the low voltage to the motor drive circuit.

## Claims

### Claim 1

An electrical power steering apparatus including;
a high voltage power source generating a high voltage of more than 100 volts;
an electrical motor generating steering assist force presented to a steering mechanism of a vehicle; and
a motor control circuit, said motor control circuit including:
a motor drive circuit including a plurality of switching elements supplying drive current to said electrical motor;
a power relay opening and closing a conduct between said high voltage power source and said motor drive circuit;
a converter division supplying power to said motor drive circuit; and
a smoothing condenser absorbing any current ripple; wherein
said converter division including a step down circuit reducing said high voltage of said high voltage power source to a low voltage lower than said high voltage, a low voltage charge device charged through said step down circuit, and a switch equipped to shut and connect a conduct between said low voltage charge device and said motor drive circuit; and
said motor drive circuit is connected with said low voltage charge device, and is disconnected from a direct connection with said high voltage power source, when a collision of said vehicle occurs, so that steering assistance is still possible but a risk of electric shock to occupants of said vehicle is prevented.

### Claim 2 (depends on 1)

An electrical power steering apparatus according to claim 1, wherein said control circuit discharges said voltage of said smoothing condenser by using said step down circuit and said motor drive circuit after said power relay is turned off at said collision of said vehicle, and turns on said switch to change to a power source from said low voltage charge device when a voltage supplying to said motor drive circuit is reduced to a predetermined low voltage.

### Claim 3 (depends on 2)

An electrical power steering apparatus according to claim 2, wherein said control circuit increases a current limit value of said electrical motor after changing to said power source from said low voltage charge device.

### Claim 4 (depends on 3)

An electrical power steering apparatus according to claim 3, wherein said control circuit detects said collision of said vehicle by a detecting signal from an acceleration sensor equipped on said vehicle, and turns off said power relay to close said conduct between said high voltage power and said motor drive circuit.