Analytical Calculation of Parallel Double Excitation and Spoke-Type Permanent-Magnet Motors; Simplified Versus Exact Model

This paper deals with the prediction of magnetic field distribution and electromagnetic performances of parallel double excitation and spoke-type permanent magnet (PM) motors using simplified (SM) and exact (EM) analytical models. The simplified analytical model corresponds to a simplified geometry of the studied machines where the rotor and stator tooth-tips and the shape of polar pieces are not taken into account. A 2D analytical solution of magnetic field distribution is established. It involves solution of Laplace's and Poisson's equations in stator and rotor slots, airgap, buried permanent magnets into rotor slots and non magnetic region under magnets. A comparison between the results issued from the simplified model with those from exact model (EM) (which represents a more realistic geometry with stator and rotor tooth-tips and the shape of polar pieces) is done to show the accuracy of the simplified geometry on magnetic field distribution and electromagnetic performances (cogging torque, electromagnetic torque, flux linkage, back-EMF, self and mutual inductances). The analytical results are verified with those issued from finite element method (FEM).