Optimization Design of Novel Consequent Pole Motor for Electric Power Steering System

This paper proposes a novel consequent pole machine (CPM) to improve cogging torque, torque ripple, and torque per magnet volume compared to a conventional CPM. The proposed structure consists of a consequent pole rotor that reduces permanent magnet (PM) material. Different from conventional surface permanent magnet machines (SPMs) and conventional CPMs, the proposed CPM has an additional iron pole (AIP) extension under the magnet. This structure is suggested in order to increase the magnet pole angle while maintaining the magnet volume by partially substituting the magnet with iron. The design of the proposed machine was optimized to achieve higher torque and lower torque ripple. Comparisons of the proposed CPM with a conventional SPM and CPM were conducted to show the superiority of the proposed CPM utilizing AIP. The results showed that the proposed CPM exhibits 68% lower cogging torque, 75% lower torque ripple, and 16% higher torque per magnet volume with the same magnet volume compared with the conventional CPM.