A novel PWM strategy to minimize surge voltage for current source converter

This paper presents a novel strategy of PWM wave control method to minimize the surge voltage at the turn off of switching devices. The sawtooth carrier is compared with the reference sinusoidal voltage, in which the polarity of the sawtooth carrier waveform is reversed alternately at every 60/spl deg/ interval relative to the fundamental wave period. It is anticipated that it is difficult to analyze the output waveforms because of its complicated current waveforms. For such waveforms, a frequency analysis approach using the switching function is presented, whose results are verified by experiments.