Analyze And Control Of The Ride Comfort And Maneuver Stability For The In-wheel Motor Electric Vehicle

Facing the challenge of world-wide environmental pollution and energy crisis, theelectric vehicle will be the best choice of the automotive industry in the future. As anunique development direction of electric vehicles, the in-wheel motor electric vehicle(IWM-EV) has a series of advantages--high transmission efficiency, great fuel economyand great controllability, etc. Therebefore, it is considered to be the final drive form.However, the unsprung mass increase and special torque ripple of IWM add adverseeffects on not the ride comfort but the maneuver stability. So, being focused on thesetwo aspects, this study includes the following aspects:First, by reviewing the time-domain and frequency-domain analysis based on1/4vehicle model, the ride comfort and maneuver stability of IWM-EV effected by largeunsprung mass are analyzed using power flow method. The simulation results show thatsince the unsprung mass increase, energy dissipation of the suspension and wheelincrease, which will cause adverse effects on the ride comfort and maneuver stability.To decrease the effects, a new shock absorber is designed and optimized. Furthermore, avibration mitigation measure of the absorber combined with an active hybrid controlintegrated the sky-hook and ground-hook is developed. The simulation results show thatthe absorber is an effective way to improve the vertical vibration. Besides, the combinedmeasure can reduce the energy dissipation further and obviously, so that IWM-EV canget greater performances.Second, taking the switched reluctance motor as an example, the torque ripple ofthe IWM is studied. The exciting force in the vertical is analyzed, whose negativeimpact on the ride comfort and maneuver stability is discussed based on1/4vehiclemodel. The simulation results show that the ride comfort and maneuver stabilityeffected by the torque ripple are concentrated in the low speed. In this case, thefrequency of torque ripple is close to the frequency of vehicle vertical vibration. So, thevertical exciting force can induce resonance easily. In view of the periodic characteristicof the exciting force, the FxLMS algorithm for active suspension control is put forward.The simulation is given to verify the effectiveness of this control.Thirdly, a full vehicle model is established. Based on the model, the ride comfortand maneuver stability of IWM-EV are analyzed. The simulation results show thatadverse effects on the ride comfort at the low speed and high speed are mainly due to the special torque ripple and unsprung mass increase respectively. The maneuverstability of IWM-EV is focused on the low adhesion coefficient road. In this case, thetire lateral force is insufficient and the vehicle can lose its stability easily.Finally, in order to improve the ride comfort and maneuver stability of IWM-EV,an active hybrid controller integrated the skyhook-groundhook algorithm and FxLMSalgorithm is developed. The computer simulation results show that the controllerbalances both algorithms and the performances of IWM-EV with this controller can beimproved. Beside, a kind of active front steering controller based on sliding-modecontrol is put forward to improve the stability of IWM-EV on the low adhesioncoefficient road. The effectiveness of this measure is verified by computer simulations.The integration evaluation of the vehicle ride comfort and maneuver stability shows thatthe performance of IWM-EV with the controllers has reached the level of integratedmotor EV basically.