A DEVICE FOR GENERATING PHASE DISPLACED WAVEFORMS FOR SWITCHING TWO SETS OF SEMICONDUCTOR SWITCHES OF A STATIC INVERTER GENERATING A STEPPED SINE WAVEFORM

摘要

A device for generating phase displaced waveforms for switching two sets of semiconductor switches of a static inverter generating a stopped sinc waveform comprisingmeans for generating a first set of N pulse trains (N being a positive integer);means for generating a ramp waveform from the first pulse of the first set of pulse trains;voltage comparator means for comparing the ramp waveform with a dc voltage obtained as a feed back from the said inverter;a phase comparator, included in PLL (phase locked loop) integrated circuit, the output of the phase comparator being filtered by a high frequency filter and fed to the VCO (voltage controlled oscillator) in the said PLL, the output frequency of which varies in accordance with the output of the said filter a divide by N client for dividing the frequency of the output of the VOC by N, the first pulse of the second set of pulse trains output of the said divide by N circuit being fed back to the said phase comparator, the reference of which is the output of the said voltage comparator means, whereby the said second set of pulse trains is always phase locked with the said first set of pulse trains, the phase difference between the second set of pulse trains output of the divide by N circuit and the first set of pulse trains being variable by the said PLL circuit.