Design of ferrite magnet CFSM to improve speed response of EPS system

Abstract

This paper deals with the speed response characteristic of the concentrated flux synchronous motor (CFSM) using ferrite magnets for the electric power steering (EPS) system. To analyze the response characteristic of the CFSM, an analytical method using the electromechanical undamped natural frequency and damping ratio based on the transfer function is proposed. By using the method, the speed response according to the variations of the shape of the permanent magnets (PMs) and rotor core is analyzed. It was analyzed under the conditions of the constant volume of the PMs as well as the constant diameter of the rotor. By using the proposed analysis method, the improved model is desgined based on the initial model fulfilling the required specifications. Finally, the torque and speed response characteristics of two motors are simulated through the finite element analysis (FEA) and MATLAB Simulink.