Induction torque and servo-motor design

IN CERTAIN APPLICATIONS for an induction motor, the performance at standstill is of predominant interest. A control motor, such as a torque motor or servo motor, falls into this category. In designing such a motor, one of the usual goals is to obtain maximum stall torque. A better criterion is to maximize the ratio of stall torque to stall input power, because the allowable power dissipation of the motor is essentially invariant. This criterion is used to derive the optimum rotor resistance, the optimum number of poles, and the optimum air-gap diameter of a control motor with prescribed outline dimensions.