Distributed Drive Electric Vehicle Torque Coordinated Control

The development of electric vehicles is gradually gaining attention,and distributed drive technology is again the most promising development direction for electric vehicles.Distributed drive electric vehicles eliminate the mechanical structure of the drive train,have higher transmission efficiency,each wheel can be driven independently,and have more diverse control methods for the vehicle.In this paper,the stability control of a distributed drive electric vehicle driven by a wheel hub motor is taken as the target,and the motor torque coordination control of a distributed drive electric vehicle is studied.Firstly,the dynamics of the distributed drive electric vehicle is analysed.The vehicle transverse angular velocity and centre-of-mass lateral eccentricity are important parameters for vehicle stability control,and the ideal transverse angular velocity and centre-of-mass lateral eccentricity of the vehicle are obtained by building a two-degree-of-freedom vehicle model.A seven-degree-of-freedom vehicle dynamics model and a wheel model are developed,and a magic tyre formulation is introduced to solve for the longitudinal wheel forces.Secondly,a direct cross-swing torque hierarchical controller is established.The MPCbased additional cross-swing torque controller in the upper layer tracks the ideal cross-swing angular velocity and the mass lateral deflection angle to calculate the required optimal additional cross-swing torque as input to the lower layer controller.The lower level MPCbased torque distributor tracks the additional swing moment calculated by the upper level additional swing moment controller and compensates for the swing moment by applying different driving forces to different motors to maintain the body attitude.At the same time,because the distributed drive electric vehicle belongs to the over drive system,the vehicle will deviate from the straight line driving trajectory when the wheel motor is disturbed by the outside world during the straight line working condition driving,considering the synchronous operation of the coaxial motor of the vehicle is more conducive to the stability of the vehicle than the synchronous operation of the same side motor,setting a greater error weight to the coaxial motor on the basis of the adjacent coupling control,optimising the parameters of the PID algorithm through a single neuron,making adjustments to each wheel torque and realising the synchronous operation of the motor.Finally,to verify the effectiveness of the direct transverse moment hierarchical controller and synchronous controller proposed in this paper for steering and linear driving conditions,the vehicle stability control system is built in MATLAB/Simulink and jointly simulated with Carsim.The results show that the direct transverse moment hierarchical controller can ensure the stable posture of the vehicle without understeering and oversteering under high-speed steering conditions,and the synchronous control system can ensure that the vehicle motor output is not synchronous to maintain linear and stable driving under linear acceleration conditions.