Ford Motor Company Limited

Casilda D De Benito

Richard Joseph Hampo

Prabhakar B Patil

Roy I Davis

A pulse width modulated (PWM) inverter is controlled by repetitively changing or dithering desired output currents for the inverter to ensure that it is unable to settle into zero states which result in lack of torque control when the inverter is used to control an AC motor. Dithering is performed by algebraically combining dither values with the desired output currents to generate reference output currents outside a hysteresis band used to control the inverter. Since the reference output currents are outside the hysteresis band, zero states are avoided. Dithering is performed by repetitively adding and subtracting first and second dither values form the desired output currents; or, repetitively adding a first dither value, adding a zero dither value and subtracting a second dither value form the desired output currents. The dither value can be approximately equal to half the hysteresis band, or approximately equal to or greater than half the hysteresis band.

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Bloomfield, MI, United States of America

Casilda D De Benito