Phase-controlled circulating current cycloconvertor-induction-motor drive using rotating intergroup reactor

The paper describes the use of an induction motor stator as an intergroup reactor in a circulating-current cyclo-convertor. A double-layer stator winding formed into electrically separate thyristor group circuits, magnetically coupled in the stator slots, provides a conventional rotating field in the airgap. This enables the double wound stator machine to act as a reactor maintaining circulating current operation in the cycloconvertor and as a torque producing motor. Standard induction motors may be additionally incorporated into the system as in a conventional cycloconvertor drive. A closed-loop speed control system is incorporated that maintains constant speed independent of load on the divided-winding reactor machine. Any additional induction motors then operate technically under open-loop conditions, but open-loop instability is avoided by the inclusion of the reactor machine in the loop.