Trw Limited

Stuart Walter Parker

Kevin M McLaughlin

Hristos K Mantjios

Current control values are established for an electric motor including providing a table of motor current control values as a function of motor operating angle, providing a torque request signal indicative of the desired amount of torque to be supplied by the motor, and providing a torque command signal having a value functionally related to the torque request signal and a feed-forward torque signal. The motor operating angle is monitored and the motor is energized using current control values from the table in response to the torque command signal. The amount of torque ripple experienced by the motor is measured when the motor is energized. The measured torque ripple is filtered using a time domain filter and a time domain filtered torque ripple signal is provided. The time domain filtered torque ripple signal is then averaged and the averaged time domain filtered torque ripple signal is then filtered using a spatial domain filter, the spatially filtered averaged time domain filtered torque ripple signal is the used as the feed-forward torque signal. The current control values output to the motor is stored as a function of motor operating angle for the provided torque request value when the torque ripple value is less than a predetermined value.

Method and apparatus for reducing torque ripple in an electric motor

A steering assist system (10) providing assist in response to a steering control signal includes a vehicle speed sensor (56) for sensing vehicle speed and for providing a speed signal having a value indicative of the sensed vehicle speed and a torque sensor (44) operatively connected to a vehicle hand wheel (12) for providing a torque signal indicative of applied steering torque. A controller is connected to the vehicle speed sensor (56) and to the torque sensor (44). The controller includes an adaptive torque filter (80) that maintains a selectable system bandwidth independent of gain changes and vehicle speed changes. The adaptive filter (80) recovers any gain reduction by increasing the frequency of a filter pole.

Growing community of inventors

Redondo Beach, CA, United States of America

Stuart Walter Parker