Design and Verification for the Torque Improvement of a Concentrated Flux-type Synchronous Motor for Automotive Applications

In this paper, the design of the concentrated flux-type synchronous motor (CFSM) using ferrite permanent magnets to improve torque is proposed for an automotive chassis actuator. The thin pancake type CFSM of this paper has considerable axial magnetic leakage flux due to structural reasons. It is, therefore, necessary to improve the torque. In order to meet the required specifications in a constrained installation space, this paper proposes two methods for torque improvement. The first method is the alternate-stacking core as this structure removes the magnetic leakage flux path. The second method is the rotor overhang that increases the air-gap flux density. Furthermore, the structures require a three-dimensional (3-D) finite element method (FEM) analysis for accuracy. However, to analyze the characteristics easily and quickly, the 3-D structure is made into the equivalent 2-D FEM through an analytical method using an equivalent magnetic circuit. Finally, in this paper, the validity of the design process and the effectiveness for torque improvement is verified through experiments.