Motorola Corporation

Temic Automotive of North America, Inc.

Ronan P De Larminat

Alexander Kurnia

Guang Rong Liu

Scott W Repplinger

A method and apparatus for measuring current by a single sensor for two motor phases driven by first and second set of switches to drive respective first and second phases of a motor under control of PWM signals. A first stepincludes reading a duty cycle of each winding drive current. A next step configuresthe PWM signals to provide at least one timing window wherein at least of one of the windings of the motor is being driven while the other winding is not being driven, and to provide a relative timing offset of approximately one-half cycle between the pulse width modulation signals driving a first winding and a second winding of the motor. A next stepincludes gating the switches with the configured PWM signals. A next stepincludes sampling the current of the at least one of the windings with a single sensor.

Current sensing in a two-phase motor

A method and system for detecting faults in an electric power-assisted steering system includes determining a voltage vector of an electric power-assisted steering motor and measuring a current vector of the motor. Acceptable angular relationships are defined between the voltage vector and the current vector, which are then compared to find a fault if the angle does not meet the acceptable angular relationship. Additionally, motor direction and position can also be used against an angular check of the voltage and/or current vector. Similarly, torque direction can be used. In this way, several different faults can be determined dynamically under transient conditions.

Fault detection in an electric power-assisted steering system

An apparatus ( ) for measuring torque and flux current in an AC synchronous drive motor ( ), having a shaft ( ) magnetically coupled to an a-phase stator, a b-phase stator and a c-phase stator, includes a shaft position indicator ( ) that is coupled to the shaft ( ) and that generates a position signal indicative of a position of the shaft ( ). A current sensing circuit ( ) generates a current signal indicative of instantaneous direct link current of the motor ( ). A sample and hold amplifier ( ) samples the current signal when a trigger input is asserted. A processor ( ) asserts the trigger input from trigger generation ( ). The processor ( ) calculates torque generated by the motor ( ) and flux current in the motor ( ) based on the current signal value and decoding algorithm ( ).

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Northbrook, IL, United States of America

Ronan P De Larminat