Soft commutation in brushless drives

The authors study continuous speed variations in small brushless polyphase drives, fed by the commercial single-phase mains. They present the interesting aspects of the combined use of different types of semiconductor components within the same static converter. They show in particular how only one switch, equipped with an appropriate environment, can allow all the others to benefit from soft commutation conditions. The classical snubber circuits then become useless, and further, the electromagnetic interference problems are considerably reduced