Active Suspension Control of Electric Vehicle Driven by Switched Reluctance Motor Based on Vibration Absorbing Structure

Active suspension control for in-wheel switched reluctance motor (SRM) driven electric vehicle with dynamic vibration absorber (DVA) based on robust H_∞ control method is presented. The mounting of the electric drives on the wheels, known as in-wheel motor (IWM), results in an increase in the unsprung mass of the vehicle and a significant drop in the suspension ride performance and road holding stability. Structures with suspended shaftless direct drive motors have the potential to improve the road holding capability and ride performance. The quarter car active suspension model equipped with in-wheel SRM is established, in which the SRM stator serves as a dynamic vibration absorber. The in-wheel SRM is modelled using an analytical Fourier fitting method. The SRM airgap eccentricity is influenced by the road excitation and becomes time-varying such that a residual unbalanced radial force is induced. This is one of the major causes of SRM vibration. Current chopping control (CCC) and pulse width modulation control (PWM) are adapted to suppress motor vibration. Moreover, a robust H∞ controller is developed for the active suspension with DVA to further enhance vehicle ride performance. A comparison of passive suspension with conventional SRM, passive suspension with DVA, active suspension with DVA on vehicle suspension and SRM dynamic responses are presented. Simulation results under bump road excitation and random road excitation demonstrate the effectiveness of DVA structure active suspension system with proposed control method in enhancing suspension and motor performance.