The Sleeve Induction Motor for High-Performance Servomechanisms

The order-of-magnitude reduction in effective inertia provided by the conductive-sleeve induction motor, coupled with advances in high-power solid-state devices, make all-electric servo systems feasible in certain applications in which the inertia of the squirrel cage or solid iron rotor would be prohibitive. Low inertia in the sleeve motor is obtained at the expense of real and reactive power requirements. This paper shows how the trade between these quantities is best made. Delay in control-field buildup in the usual servomotor control system may prevent full realization of the high performance of the sleeve motor. Constant-flux variable-frequency control of both phases is proposed as a method of eliminating this time delay.