New static controller for d.c. machines

The paper first considers the merits of a single-phase static Ward-Leonard drive. It is found that the drive has limitations which lead to poor speed regulation. A new, simple, static control device is described which gives improved performance. The control device can be used with an ordinary d.c. shunt machine to give shunt, series and compound characteristics in both generating and motoring modes. The device operates on the principle of monitoring the armature current, and, by the aid of feedback control, the field current is regulated to any desired machine operational mode. A theoretical analysis is verified by practical results.