Virtual Work Principle Formulation for Force and Torque Calculation of Magnetic Systems Including Permanent Magnets

초록

In this paper, the virtual work principle (VWP) formulation is presented for the force and torque calculation of the magnetic systems. The derived formulation is applicable to the general magnetic systems that include permanent magnets and nonlinear cores. For verification, the magnetic force of an electromagnet model is calculated using VWP and compared with that obtained using Maxwell stress tensor (MST) method. Based on the error analysis, a guideline is presented for selecting the proper size of the virtual displacement, which is essential for the accurate force calculation using VWP. The proposed method is applied to the optimal stator shape design of a BLDC motor model for the cogging torque reduction, and the change of the optimal shape and torque is analyzed according to the weighting factors of each term in the multi-objective function.

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