Comparison of the torque & slip curves for a standard squirrel cage motor with those of a motor with a novel winding arrangement

Abstract

This paper complements others by the same authors [1], [2], where the general concepts, design calculations and constructional differences of an induction motor with a novel winding arrangement were presented, together with a magnetic analysis. In the present paper, the equivalent circuit for the space harmonics of the mmf is described and the slips and equivalent circuit parameters for each space harmonic are calculated, together with the current, power and torque for both the standard squirrel cage motor and the motor with the same rotor but a novel stator winding. The negative effects of the space harmonics are calculated and presented graphically for both motors. Torque and slip curves are obtained for 6000 points in a speed range between 3000 min-1 and -3000 min-1. It is shown that the negative effects of certain space harmonics are eliminated by the constructional changes. A comparison between the torque-slip characteristics of the two motors is presented, and the improvement in the overall torque characteristic shows the benefits resulting from the adoption of an innovative approach to the winding.