Winding Comparison of Symmetrical Dual-Three Phase PMSMs with PWM Carrier Phase Shift considering Leakage Inductance

Abstract

Torque ripple and acoustic vibration in dual three-phase drives can be mitigated by introducing a carrier-phase shift between the two inverters (CPS-PWM). Although this scheme suppresses torque ripples, it also amplifies high-frequency current ripple because the two winding sets are magnetically coupled through their leakage inductance Lls; the resulting rise in copper and iron losses can negate the expected benefits. This work quantifies the influence of Lls on CPS-PWM performance. An analytical model is first developed to link Lls to the switching-ripple components of the phase currents. The model is then validated by time-domain simulation and finite-element analysis using three winding layouts that provide low, medium, and high leakage inductance. Results show that a larger Lls markedly reduces PWM-induced current ripple, yielding the smallest torque ripple and almost no efficiency penalty, whereas a very small Lls can increase both torque ripple and total loss. The study thus offers clear design guidance for selecting winding configurations when CPS-PWM is applied in dual three-phase machines.