Current Control Scheme for Solid State DC Motor Drives

Solid state dc motor drives are becoming increasingly popular. The inherent disadvantages of such drives are studied by considering a separately excited dc motor fed from a single-phase thyristor converter. The discontinuous and highly rippled armature current in solid state dc drives affect the commutating capability of the dc motor and its static and dynamic performances. A novel current control scheme is outlined which can restrict the amplitude of the current close to its average value and make current continuous over a wide range of operation. This converter-motor system with current-control-scheme is simulated on an analog as well as on a digital computer. The system is found to be potentially capable of providing various useful torque-speed characteristics without any change in the field circuit. Experimental results demonstrate the feasibility of the system.