CONTROL METHOD FOR AN INVERTER WORKING WITH PULSE WIDTH MODULATION, AND DEVICE FOR CARRYING OUT THIS METHOD

摘要

The circuit of the control device consists of two branches generating the waveforms for three-phase edge-controlled flip-flop sampling units followed by correctors which produce clean width-modulated pulses. The upper branch of the control circuit contains a HF square-wave generator whose output is divided by 96 and amplitude-regulated by a unit connected to a desired-value generator. A filter (14) produces a sinusoidal signal at about 100 kHz for comparison with the chopping signal from a triangular-wave generator. In the lower branch a fundamental signal is generated and synchronised with the square wave, to which it is added before division into three sampling signals at 120 deg. phasing. The correctors of the sampled waveforms eliminate multiple transitions. The circuit controls a three phase asynchronous motor.