Distributed Short-Pitch Winding for Multi-Phase Pole-Phase Modulated Induction Motor Drives

Abstract

In multiphase induction motors the number of slots per pole per phase comes down due to the higher number of phases, which results the airgap MMF per phase closer to square wave. In addition, as the number of poles increases the space harmonics will increase further in Pole-phase modulated induction motor drives (PPMIM) drives. To address this issues, in this paper a distributed short pitch winding (DSPW) is proposed for PPMIM drives. In DSPW, the number of conductors per phase are distributed over three stator slots that will generate the multi-stepped MMF wave in airgap as compared to concentrated winding. Because of this, the space harmonics in the airgap as well as the harmonics in induced EMF will come down, which improves the performance of the drive. The PPMIM drive with proposed DSPW, is capable to operate in 9-phase 2-pole mode and 3-phase 6-pole mode without changing the stator winding connections. A 5hp, nine-phase PPMIM drive with the proposed DSPW is designed by using Ansys Maxwell 2-D FEM tool. The power circuit is designed in Simplorer environment (associated tool for Maxwell 2-D) for co-simulating the Maxwell model of PPMIM drive. Moreover, the torque ripple percentage of PPMIM drive for both concentrated winding as well as for distributed winding has been compared. The proposed drive will offer the wider range of speed and torques which is best suitable for traction and ship propulsion applications.