Reducing Torque Pulsation of Multi-Phase Interior Permanent Magnet Machines

High torque pulsation is the major disadvantage of most IPM machine configurations. Choosing proper number of stator slots and winding distribution as well as increasing number of phases are among the possible solutions for reducing torque pulsation. In this paper, multi-phase interior permanent magnet motors with fractional-slot stator and double layer winding distribution are studied. It is shown that despite other IPM machines; the introduced multi-phase IPM machines have a very low torque pulsation. Seven and nine-phase IPM machines have been designed using the same method. The approach can be extended to the machines with any number of phases. For comparison purposes, IPM machines with common configuration are also considered. It is shown that the torque pulsation of the proposed IPM machines is significantly lower than the conventional ones. Nonlinear finite element method is used to analyze different machine configuration.