Control device for a pulse-width modulated inverter

摘要

A control device for a pulse-width modulated inverter comprises means for generating as a carrier wave a triangular wave synchronizing with an AC output from the inverter, means for generating as a modulating wave a train of rectangular wave pulses which synchronize with the triangular wave and have a width corresponding to a section effective for a modulating operation and a predetermined amplitude, voltage level setting means for setting the amplitude of the train of rectangular wave pulses, and means for modulating the triangular wave with the train of rectangular wave pulses and generating a control pulse for the AC output. The rectangular wave pulses are so set as to have a modulating level of zero in the proximity of a point corresponding to the zero point of the AC output of each phase thereby to remove a frequency divider for adjusting input frequencies of the triangular wave generating means and the modulating wave generating means and to prevent a useless modulating operation leading only to an increase in the number of commutations of the inverter.