Rotor Current and Magnetic Field Variations in Induction Motors with Skewed Rotors

Published methods of calculating induction motors do not reflect the effect of skew on the magnetic field in the air gap. The rotor bar current as affected by skew alters the total mutual field. This paper determines the voltages induced in both the rotor bar and the primary winding as affected by the said modified field and provides equations to calculate its effect on performance. This paper also analyzes the field resulting from non-skewed stator conductors carrying line current and skewed rotor conductors carrying rotor bar current. Rotor current is calculated in terms of individual bar currents; present techniques use uniform current sheet distribution. Equations are given to calculate motor performance reflecting the effect of skew on the mutual field.