On performance figures of multiphase machines

Abstract

Various performance aspects of multi-phase machines are investigated with the main focus on 6-phase (dual stator) synchronous machines. It is shown that 6-phase machines have benefits over their 3-phase counterparts regardless of machine topology i.e., PM, induction or synchronous. Differences between 6-phase and 3-phase machines are emphasized through detailed design parameter sensitivity. It is revealed that choices such as material for wedges, pitching, etc. have distinct impacts on the two layouts. By studying the effect of phase shift between the two 3-phase systems it is shown how this affects machine losses as well as space harmonic patterns. This can be beneficial when compensating harmonics by controlling the converter. A brief study of 9 and 12-phase synchronous machines shows the potential when going to even higher phase numbers when considering torque density and torque vibrations.