PWM WAVEFORM CONTROL METHOD FOR MULTIPLE INVERTER

摘要

PURPOSE: To make it possible to prevent the occurrence of low-order harmonic current by taking OFF delay and ON delay for a gate drive signal thereby providing dead time and by advancing the control signal of an inverter by the dead time. ;CONSTITUTION: Gate drive signals are output as same as the initial control signal by deviating the control signals by dead time (b-a) in an arrow direction only for those having arrow marks by the control signal at the ON and OFF timing positions. That is, in the conventional gate circuit, a delay (b) in ON is made larger than a delay (a) in OFF (since OFF delay is made smaller for quickening the OFF operation of GTO when overcurrent conducting of GTO) and, by doing this, the delay in ON greatly contributes to the deformation of waveform in AC output waveform. Therefore, a pulse at the upper side of the output voltage waveform is formed by AND conditions of ON for U and Y, so that a correct measure can be taken by deviating by (b-a) the timing caused by the delay in the output waveform of U and Y.;COPYRIGHT: (C)1996,JPO