Circuit arrangement for generating a pulse-width modulated signal

摘要

A digital device for controlling a three-phase motor comprises a circuit arrangement for generating three pulse-width modulated carrier waves which are 120 DEG phase-shifted relative to each other, whose modulation depth as a function of time represents a sinewave. A first clock signal periodically starts an up/down counter which counts the second clock signal. The carrier wave is generated by switching a flip-flop each time that the maximum count of the up/down counter is reached and the various modulation pulses which are required are generated symmetrically relative to this maximum count. A sequential network modulates the carrier wave sequentially with the correct modulation pulses.