Operation of the naturally commutating hidden link converter feeding a cage induction motor

The authors describe the principles of operation of the hidden link naturally commutating converter for the variable speed control of a cage induction motor. Initial investigations have shown that with direct converter-motor connection, the converter is naturally commutating for machine frequencies from zero to near supply frequency. The natural commutation of the converter feeding a lagging power factor load is made possible by an implicit frequency modulation of the output current waveforms. The associated problems and possible applications of the scheme are discussed