Linear Modulation Range and Torque Ripple Profile Improvement of PPMIM Drives

The pole phase modulated induction motor (PPMIM) drives facilitates the extended range of speed-torque characteristics, which is an essential requirement for traction and electric vehicle applications. For getting the wider speed-torque variations, 15- $\Phi$ PPMIM drive is analyzed, which is capable to operate at 2-pole 15-phase, 6-pole 5-phase and 10-pole 3-phase modes. In these pole phase operations, in high phase and low pole mode of operation, the increment in the linear modulation range with SVPWM is not significant. In the low phase and high pole mode of operation, there will be higher torque ripples due the higher magnitude of space harmonics. In this paper, these issues are addressed by using carrier phase shifted space vector pulse width modulation (CPS-SVPWM) and phase grouping concepts. In low pole operation, the linear modulation is enriched by using conventional 3- $\Phi$ SVPWM to drive 15 phase machine by appropriately reorganizing the phase winding connections. Similarly, in 6-pole 5-phase mode of operation the linear modulation range of PPMIM drive is enriched by using 5- $\Phi$ SVPWM. It is known that in high pole mode of PPMIM drive operation each effective phase is formed by the multiple number of equal voltage potential coils (EVPC), which are electrically in phase. The carriers of these EVPCs per phase are phase shifted by an appropriate angle to minimize the harmonics in the effective phase voltage, which results in better torque ripple profile. In addition, the detailed comparison of three possible different CPS-SVPWM's are presented, with their pros and cons for selecting the proper carrier phase shift angle. The performance of the proposed scheme has been validated by Ansys Maxwell 2-D as well as laboratory prototype on 5hp, 15- $\Phi$ PPMIM drive