A Magnetic Pole Modulation Method on Surface Permanent Magnet Machines for High Performances With Different Magnetization

This study proposes a magnetic pole modulation method applied to surface permanent magnet (PM) machines for suppressing the torque pulsations and improving the utilization of the magnet. The principle of equivalent areas is more popular in power electronics instead of the sinusoidal current. Here, the principle is modified into magnetic pole modulation to create an air-gap flux density distribution with a sinusoidal wave. Subsequently, the third harmonic is considered in the magnetic pole modulation method. Radial and parallel magnetization have both been discussed with this method for its availability. Additionally, an optimal design process combining the Kriging method with a genetic algorithm is applied to design the key parameters for further minimizing torque pulsations and maximizing output torque per unit PM. All motor characteristics, including air-gap flux density, cogging torque, and electromagnetic torque are verified by the aid of finite-element analysis.