A novel SHEPWM scheme for reducing torque pulsation of dual three-phase induction motors

The dual three-phase induction motors can eliminate the pulsing torque of 6 times the fundamental frequency. In order to acquire more improvement, the lowest pulsing frequency should be increased further while the magnitude decreased. Torque pulsation is caused by the harmonic currents of order 6nplusmn1 (n=2, 4......). So the key to eliminating the pulsation is reducing the substantial harmonics of the 11th and 13th orders. In this paper, a scheme of special harmonics elimination (SHE) PWM is proposed to solve the problem of torque pulsation. The proposed PWM, which is derived by comparing the difference between a dual three-phase system and a fourfold three-phase system, has the same function as traditional SHEPWM.