Abstract
Electric power steering (EPS) systems have rapidly permeated the market and are increasingly being used in passenger vehicles worldwide. Steering systems are operated at a variety of different steering speeds, and EPS system motors are therefore used under all conditions, from low to high rotational speeds. In the high-load, high-speed range of operation in particular, motor vibration is transmitted to the cabin, reducing the commercial appeal of vehicles with EPS. The research discussed in this paper identified the causes of vibration components that were transmitted to the cabin, and increased the rotational support stiffness of the rotor to reduce the fundamental harmonic components of motor vibration. Furthermore, to reduce motor torque ripple, this research focused on changes of the magnetic flux density crossing the stator teeth. The magnetic circuit was redesigned to increase the smoothness of changes of magnetic flux density. This research has reduced cabin noise, and resulted in the development of a motor that is well suited to EPS systems.
Keywords - EPS, motor, cabin noise, vibration, torque ripple