The Analyze And Research Of The Stability Control Of Electric Vehicle

From the appearance of the electric vehicle up to the present, the keystone of the research is for good fuel economy and low emission. With the development of technology, the electric vehicle has played active action in improving the energy security and air pollution. The safety performance of the electric vehicle which is important to the stability of the vehicle and security of the people's life has been paid less attention yet, it is necessary to do some research in the aspect of the safety performance of the electric vehicle. Some groping research in how to improve the stability of the electric vehicle has been done in this thesis.The object of the research is the four-wheel drive electric vehicle which is ameliorated from prototype car.Based on the five freedom degree simulation model of prototype car which has been validated and the in-depth analysis of the configuration difference between the electric vehicle and prototype car, the simulation model of electric vehicle with seven freedom degree has been constructed to keep on the research. The transformation of the yaw moment under differential brake and the impact of the slip ratio and road surface friction coefficient to the yaw moment were analyzed. The distribution method of the brake force was confirmed. After analyzing the observability of the control system, the state observer was designed, the evaluation of the side slip angle was completed and result of the evaluation wan validated. The direct yaw moment controller with the feedback of side slip angle and yaw rate was designed. Based on the ideal yaw model of zero-side slip angle, the control arithmetic of the feedforward direct yaw moment was studied and the optimal control strategy of LQR and LQI on the basis of feedback was designed. For the slip of the wheel, model following controller was designed and the anti-slip control strategy based on the model following was confirmed.Simulations were done under the two typical conditions of the leap and sine, using the combination control of the feedforward and feedback. The result showed that the method of combination control could greatly improve the stability of the electric vehicle. Simulations were also done to the slip phenomena under the conditions of the driving and braking. The result showed that the anti-slip control strategy confirmed could effectively reduce the slip ratio of the wheel and improve the stability and safety of the electric vehicle.