Research On Stability Control Strategies For Distributed Drive Electric Vehicles

In the face of the dual crisis of increasingly exhausted energy and deteriorating environment,electric vehicles have slowly started to emerge as a leading trend in the automotive sector,and electric vehicles with distributed propulsion are being pursued in the automotive industry.based on their advantages of high efficiency.The DDEV is operated separately from four motors located in the wheel arches,and each motor could be regulated differently.Therefore,it is crucial to address the stability control strategy of distributed drive vehicles in terms of enhancing the vehicle’s driving stability.Firstly,the vehicle is modelled parametrically using the dynamics system supplied by the company’s Carsim software,changing the traditional drive form to an integrated motor drive,and building the integrated motor model and the driver’s speed control model in Simulink.The platform for shared driving electric vehicle motion dynamics simulation is built,and the external interface of the application software is set up to realise the shared simulation.Aiming at the problem that some vehicle state parameters cannot be directly measured at present,An extended Kalman filter estimator is developed based on three degrees of freedom vehicle model combined with EKF theory algorithm.The state parameters of vehicle stability and longitudinal speed are estimated.And through double shift and serpentine conditions simulation verification,the simulation results show that the estimated value of vehicle state parameters can track the actual value of the vehicle very well,which proves the effectiveness of the estimator.A multi-level system stability regulator is presented to address the lateral stability issue of the vehicle.The desired extra yaw torque to retain the vehicle stability is derived by defining the minimum error of two state parameters,centroid lateral deflection angle and lateral angular velocity,and the predicted value as the feedback target.The subordinate control system applies the torque based on two torque allocation strategies,one is based on wheel load distribution considering vertical load variation of the vehicle,and the other is based on tire load rate optimization considering dynamic constraints.According to the results,Under both conditions of poor road surface adhesion,the two torque distribution strategies could decrease the error of rolling stability state parameters to different degrees,indicating that the optimisation of driving stability has a good effect.Taking into account the constraints of vehicle operations,a hierarchical control method is employed to establish a distributed drive vehicle stability controller model via Model Predictive Control(MPC)based on a 3 DOF vehicle dynamics model in the upper layer;the torque distribution is supplemented by a quadratic planning algorithm in the lower layer.According to the results,the controller can shorten the stability arguments like lateral yaw angle of the main centre of the weight and the yaw speed,and enhance the vehicle stability well.With respect to the controller designed earlier,it can be seen that the controller based on model predictive control has a better effect on improving the vehicle driving stability by integrating the improvement ratio of different indexes.