A NOVEL PWM STRATEGY TO MINIMIZE THE SURGE VOLTAGE FOR CURRENT-SOURCECONVERTERS

This paper presents a novel technique of pulsewidth modulation (PmTM) wave control to minimize the surge voltage at the turn off of switchin g devices. Two kinds of sawtooth carriers with different hypotenuses a re employed to obtain a PWM waveform with minimum surge voltage, where each sawtooth carrier appears alternately at every 60 degrees interva l relative to the sinusoidal wave cycle, It is difficult to analyze th e output waveforms because they are complicated. In order to obtain th e analytical result, a frequency analysis approach using a switching f unction is proposed the results of which are verified experimentally.