Comparative Study of Motor Topologies for Electric Power Steering System

Electric power steering (EPS) plays a critical role towards safety and comfort especially for modern vehicles with ever-increasing complexity. The evolution of EPS technologies require not only vehicle dynamics and fuel efficiency but also higher standards of steering function. Apart from providing essential electromechanical energy conversion, the performance of EPS motor has received attention from industry and academic community in terms of high torque/power density and low level of noise and vibration. This paper details aspects of design and analysis of permanent magnet synchronous motor (PMSM) for EPS application. Furthermore, the concept of multi-phase motor is adopted factoring redundancy design in achieving fail-operational for safety critical applications such as steer-by-wire (SbW) system for autonomous driving. The motor topologies investigated have been modelled utilising Motor-CAD software.