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.

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... mental results show that the proposed method is very effective in suppressing the cogging torque of an IPM motor. Index Terms-Finite-element method (FEM), interior permanent-magnet (IPM) motor, sensitivity analysis, shape optimization.