Optimal Angle Combination for Improving Electromagnetic Torque in Induction Motor With Double-Skewed Rotor

Double-skewed rotor is of great benefit to decrease harmonic magnetic fields in induction motors. But the fundamental magnetic field is damaged as well as the electromagnetic torque, like the case of normal skewed rotor. The effect of skew angle and stagger angle on the fundamental torque is studied in this paper. With the multi-slice theory, the double-skewing factor is proposed to determine the range of angle combination. Then, the range is shortened by the deduced torque coefficient with virtual displacement method. Compared with the general recommendation, the final angle combination is optimal and widely suitable for the double-skewed rotor. A higher pullout electromagnetic torque will be attained under this condition. With the finite elements-method, the validity of analysis model can be verified by the comparison of two kinds of motors.