3-Phase Power Converter For Induction Motors

EE December 1987 APPLICATION NOTES The contents of this column are based on information obtained from manufacturers in the electronics industry, or their representatives, and do not imply practical experience by Elektor Electronics or its consultants. 3-PHASE POWER CONVERTER FOR INDUCTION MOTORS by K. Wetzel & W. Schumbrutzki* A newly developed integrated pulse-width modulator and fast switching power FETs are the key components in a converter design which allows the good control characteristics of DC motors to be achieved with the more versatile 3-phase motor. The most widely used three- phase motor is the squirrel cage type. Its features are well known. Having no commutator or brushes, it gives a long ser- vice life and runs very quietly. As there is no brush arcing, RFI suppression is not required. Because of the three-phase rotating field the motor has high starting and pull-out torque, is overload-proof and takes very little space. The rotational speed is determined solely by...