A Vector-Controlled Cycloconverter Drive for an Icebreaker

A high-power high-performance variable-speed drive system using a cycloconverter-fed synchronous motor is described. The control uses the field-orientation principle to give the drive system good steady-state and dynamic performance criteria. The accuracy of the field orientation is improved with the use of current regulators operating in the airgap flux reference frame. The system was manufactured to deliver 16 000 hp to the twin propeller shafts of a Canadian Coast Guard icebreaker. The electric components of the system were tested as a unit in the factory and the desired system performance was achieved.