A saturistor motor for pump drive with SCR speed control

This paper describes a novel electronic scheme for speed control of an induction motor driving a pump or fan. The low-slip motor used in the test program was given a flat torque-speed curve and a low starting current by locating bars of Alnico 9, which has a large hysteresis loop, in the rotor leakage flux paths. Motor voltage and, therefore, motor speed was varied by delayed firing of SCRs, or thyristors, which were connected full wave delta in the neutral of the wye-connected stator winding. The control loop uses an analog signal to hold a desired speed, or torque, or power.