Minimizing torque ripple in permanent magnet synchronous motors with polymer-bonded magnets

The paper presents a method for determining the main design parameters of a permanent magnet (PM) motor that will reduce the total torque ripple. First, the magnet arrangement is derived by one-dimensional field analysis coupled with a multiobjective minimization technique. Then, a two-dimensional model is used to further optimize the magnet arc width and minimize the cogging torque. The analysis mainly focuses on a rotor that is completely covered by the permanent magnets. In this configuration, the permanent magnets can be made from a tube of polymer-bonded magnet, and manufacture of the motor is greatly simplified. We present experimental tests of a machine manufactured on the basis of our design procedure.