Optimal shape design of iron core to reduce cogging torque of IPM motor

This paper presents a practical design method to dramatically reduce cogging torque of an interior permanent-magnet (IPM) motor without deteriorating other performances. Using the continuum sensitivity analysis combined with the finite-element method (FEM), the optimal shape of a rotor is investigated. The Lagrange sliding interface technique and an objective function expressed in terms of stored system energy allow fast convergence and simple implementation of the optimization algorithm. Experimental results show that the proposed method is very effective in suppressing the cogging torque of an IPM motor.