Application of Linear Switched Reluctance Motor for Active Suspension System in Electric Vehicle

Electromagnetic active suspension system is considered to have improved stability and better dynamic response, compared to the hydraulic active suspension system. To investigate the influence of suspension parameters on system characteristics, the frequency response of quarter vehicle model is analyzed through Bode plots by varying the spring stiffness and damping coefficient. The sprung mass acceleration, suspension deflection and tire deflection are investigated respectively. This paper proposes a novel electromagnetic suspension system, comprising of a linear switched reluctance motor (LSRM) and a passive spring. The mechanical and electrical characteristics of the proposed linear motor are obtained and verified by using two-dimensional finite element method (FEM). The magnetic flux densities at specific translator positions are demonstrated. In order to study the feasibility and evaluate the performance of the proposed suspension system, a LQR optimal controller is developed and simulated with the quarter-vehicle model. The sprung mass acceleration, suspension deflection and related force applied by the actuator are investigated under different road disturbance. Both frequencies of disturbance are approximate to the suspension natural frequencies, which are the most severe working point of active suspension system. Simulation results demonstrate that good dynamic response and better ride comfort can be achieved by the proposed active suspension system.