Cogging Torque Target and Design of Motor for EPS

This project studied a DC brushless motor for an EPS system that would not cause control performance to decline even when the vehicle was operated with a low steering angle at high vehicle speeds.

First, a target for cogging torque was established to ensure that control performance did not decline at high vehicle speed. To set the target, a lane changing simulation using a human-vehicle system model was conducted.

A brushless motor structure was designed to achieve this target value, and the magnitude of cogging torque for this design was predicted using FEM analysis. The issues were found when a prototype of this motor was constructed and the knowledge was obtained during the process of analysis were discussed, in addition the design guidelines were proposed to solve these issues. A new prototype brushless motor was constructed on the basis of these design guidelines, and tests showed it to possess suitable cogging torque for an EPS system.