Advanced random pulse width modulation technique for voltage-controlled inverter drive systems

The principles of an advanced random pulsewidth modulation (ARPWM) technique are presented. The means to alleviate the current deterioration at a low modulation index are investigated, along with the problem of the feasibility of the RPWM technique at supersonic, i.e., on the order of tens of kHz, switching frequencies. The results of computer simulation of the improved ARPWM technique and an experimental investigation of a prototype modulator are presented. Simple in practical realization, the ARPWM technique yields high-quality output current in voltage-controlled, three-phase inverters. The blurred harmonic spectra of the output voltage and current improve the acoustic and electromagnetic interference (EMI) characteristics of the inverter and can stave off resonant torsional vibrations in AC drive systems