Nonlinear Force Model of Electromagnetic Damper and Its Influence on Vibration Control

In this paper, a nonlinear force model of an electromagnetic damper (EMD) is established and the model’s parameters are obtained by experiments. The effect of nonlinear force on vibration control of vehicle suspension system is analyzed by comparing the simulation data. Firstly, according to the mechanical and circuit structure of the EMD, a nonlinear model including electromagnetic force, friction force, and inertial force is established. Based on the EMD bench test, the mechanical parameters of the DC motor and the ball screw are obtained by the least square method. Then a quarter-car model including the electromagnetic suspension is established. By analyzing the transmission rate of the suspension response to the road excitation, the nonlinear force of the EMD shows an obvious influence on the high-frequency vibration performance of the suspension. Finally, using the linear quadratic regulator (LQR) controller combined with the control logic of the semi-active EMD, the vibration control performance of the vehicle suspension under bump and random excitation is analyzed through numerical simulation. The results show that the nonlinear force of the EMD deteriorates the sprung mass acceleration (SMA) and the dynamic tire deformation (DTD), but improves the deflection of suspension (DDS). Moreover, in the nonlinear force of EMD, the influence of inertia force on suspension vibration control performance is more obvious than friction force.