Performance Comparison of Different Methods of Torque Ripple Reduction for Permanent Magnet-assisted Synchronous Reluctance Motor

In recent years, synchronous reluctance machines (SynRM) have been widely used in many different industrial applications because of their high efficiency, fast dynamic response, robustness, and lower production costs, making them suitable for traction applications. However, their usage is limited due to their low power factor and high torque ripple. To improve the power factor Ferrite magnets are commonly used in their rotor (PM-assisted SynRM). Adding these Ferrite magnets increases the torque ripple as well. To enhance the torque ripple many different methods are proposed such as skewing, employing different winding configurations, and rotor topology modifications. Machine designers should select a suitable technique as each method has limitations. This paper is aiming at analyzing the effects of these three different methods on the performance of the machine. A four-pole 1.5 kw SynRM is designed and the magnets are placed in the barriers of the rotor while keeping the insulation ratio constant then the performance of different methods is evaluated and compared. First, the rotor is skewed, and then a short-pitch winding is used for the stator. Finally, a new design for barrier ends is proposed, and their effect on the torque profile is independently evaluated. The simulations are done in 2D FEM and the results are evaluated and discussed.