Design of IPMSM Applying V-Shape Skew Considering Axial Force Distribution and Performance Characteristics According to the Rotating Direction

Skew is a common method to reduce torque ripple and cogging torque. However, when skew is applied, unexpected axial force is produced. To reduce axial force, V-skew is used as one of the solutions. Specifically, when V-skew is applied, the magnetic flux distribution changes according to the rotating direction, which causes a difference in the performance. For the application in which the motor rotates in one direction, this phenomenon can be used to produce power with better quality torque and less losses. In this paper, the interior permanent-magnet synchronous motor (IPMSM) is designed by applying a V-skew to the stator, taking into consideration the manufacturing difficulties with applying a rotor skew to the IPMSM. The skew effect and the reduction of axial force are verified based on finite-element analysis. Moreover, torque, axial force, and losses are comparatively analyzed according to the rotating direction. All calculations and analysis are conducted based on 2-D and 3-D finite-element analysis.