The Cycloconverter Driven Doubly-Fed Induction Motor

A variable speed electric drive system has been developed in which the speed-torque characteristics of a dc series motor have been attained without the need for a commutator. Improved utilization of active material has been achieved by using series-connected polyphase ac windings on both the rotor and the stator of the rotating machine and by maintaining a favorable torque angle relationship between the rotor and stator MMF waves. Torque angle is controlled by means of a shaft coupled transducer which controls the firing of silicon controlled rectifiers (SCR's) in a variable frequency inverter or cycloconverter type of ac power supply.