Comparison of PMSM and Inverter Efficiency for Dual Three-Phase High Performance Powertrains Including Low Order Harmonics and Voltage Modulation

Multiphase powertrains offer advantages in terms of torque ripple and fault tolerance [1] but are rarely investigated or compared in terms of efficiency. Therefore, this paper compares machine and inverter efficiency of two dual three-phase powertrains. Both differ only in the winding scheme of the PMSM. The first incorporates two three-phase winding sets with an electrical phase shift of 30° creating six asymmetrically placed phases. As the winding of the other machine consists of two three-phase windings with 0° electrical and 180° mechanical phase shift it is identical to a three-phase winding in terms of electromagnetic layout, but the powertrain benefits from sharing the power between six phases. Therefore, the impact of phase layout can be investigated. This includes modelling of harmonic currents due to winding layout and voltage modulation.