Pulsating torque and losses in multiphase induction machines

In this paper, the authors take a high-level look at multiphase induction machines in order to examine those aspects that are not design specific. They show that for a machine in which the only design variable is the phase number, the main target for loss reduction is the stator copper loss, which by the use of more than three phases may be attenuate by as much as 8.5%. In addition, a general expression for the harmonic fields produced when a machine having any phase number is excited from a PWM inverter is derived, and the sources of torque pulsation are identified.