Implementation of Variable-Delay Random PWM for Automotive Applications

This paper presents the implementation of variable-delay random pulsewidth modulation (VD-RPWM) for an automotive traction drive inverter. RPWM is desirable as a means of reducing electromagnetic emissions from the inverter and minimizing electromagnetic-compatibility filtering requirements. It can also serve in reducing acoustic noise generated by the drive. The algorithm is implemented on a power-PC-based microprocessor. Experimental results are presented to verify the operation of the algorithm and its compatibility with basic motor-control functions. Spectrum plots of the phase current and voltage demonstrate the effectiveness of the technique in mitigating electromagnetic interference. The effects on torque ripple and acoustic noise are also investigated