A new method for impedance control of induction motor speed

A novel induction machine with continuous speed control is found possible. This motor may be regarded as an inverted version of a Schrage motor in construction in that the tertiary winding is placed along with the secondary (on the stator) rather than with the primary (on the rotor). Hence a static commutator connected to the tertiary winding with the brushes placed over it at the appropriate places helped in injecting an EMF (of slip frequency) at various angles with respect to the secondary EMF induced by brush rotation. This has resulted in speed control of the induction motor. The performance characteristics of the new motor resemble those of a series-regulated induction machine in contrast to the shunt characteristics of a Schrage motor.