| In recent years,affected by energy and environmental problems,electric vehicles have developed rapidly.Due to its unique drive system structure,distributed drive vehicle has the advantages of high controllable degree of freedom,rapid dynamic response,accurate control of vehicle longitudinal and yaw motion,which brings a new direction for the development of electric vehicles,and also puts forward higher requirements for vehicle and motor control algorithm.In this paper,the yaw stability of the four in-wheel motors drive electric vehicle and the drive control of in-wheel motor based on permanent magnet synchronous motor is studied.Firstly,according to the requirements of the control system,seven degrees of freedom vehicle dynamics model,Dugoff tire model,wheel model and so on are established by Matlab / Simulink software to form the vehicle model,which provides a simulation platform for the subsequent debugging and verification of the control method,and the simulation platform is verified by Car Sim software.Aiming at the problem of yaw stability control of distributed drive electric vehicle,the sideslip angle and yaw rate are selected as the control objects,and a reference model is established to provide the ideal sideslip angle and yaw rate for the yaw moment controller.A new sliding mode controller is studied to control the two control variables respectively,then a weighting function is employed to get the two controllers together to get the final direct yaw moment.A torque distributor is established to distribute the direct yaw moment to the four wheels,and the direct yaw moment is generated to maintain the vehicle yaw stability through the speed difference between the left and right wheels.The Simulink vehicle model and Car Sim software are used for simulation verification,the results show that the new sliding mode controller proposed in this paper can effectively control the vehicle yaw stability and has a better control effect.Aiming at the problem of in-wheel motor control based on permanent magnet synchronous motor,firstly,the vector control strategy is studied,and a control method of motor speed and torque is given.To improve the control precision,according to the characteristics of high speed of the in-wheel motor,a new reaching law sliding mode controller was proposed to control the speed.The load observer is established,and the observed values are used to control the speed.The simulation results show that this method improves the accuracy of speed control.In order to further optimize the motor control system,the direct torque control strategy of motor is studied and a method of motor torque control is given.According to the requirement of large value and large variation of motor torque,the traditional exponential reaching law is further improved,and the improved sliding mode controller is obtained.The simulation results of the motor model and vehicle model show that this control method has a good control effect,and has certain practical value in improving the response speed and output stability of the control system. |
