Analysis of a Mechanically Doubly Salient Electric Machine using FE and Lumped Parameter Magnetic Equivalent Circuit Models

Analysis of a special machine topology, which features a doubly salient structure and permanent magnets in the stator and provides very high power density performance has been presented in this paper. An analytical model for the proposed machine has been developed using lumped parameter magnetic equivalent circuits (LPMEC) of the stator segments, permanent magnets (PM), toroidal windings, air gap, and reluctance-type rotor. Previously published analytical techniques have not thoroughly explored spatial harmonics, which is done in the proposed methodology, yielding a high-fidelity model. The machine analyzed is highly suited for electric vehicle traction applications and consists of 12 stator segments and coils, separated by 12 PMs in the stator, and a reluctance-type rotor with 10 protrusions. The LPMEC model has been analyzed to compute flux linkages, open circuit back EMF, and inductances with respect to the rotor position, and these results have been verified using finite element method. The analysis shows that despite its doubly salient structure, the proposed machine exhibits the characteristics of a non-salient machine, and this behavior has been validated by analyzing spatial harmonics and static torque test.