Research On Driving Force Control Method Of Wheel Drive Electric Bus

With the energy crisis deepening and the air pollution caused by fuel vehicles increasing constantly,it is a effective way to search and improve the dynamic system of vehicles in alleviating the problem,therefore,the research institutions and coach manufacture no matter it is domestic or oversea are devoted to studying and popularizing the electric coach enthusiastically.Under the background of such circumstance,the distributed drive coach is subjected the attention of the researchers both at home and overseas due to its special structure and performance characteristics.The driving force of the distributed drive system can be controlled separately,its main structural character is distributing the drive motor to each wheel which is characterized by short drive chain,high transmission efficiency,compacting structure and utilization rate in the vehicle interior space.As the stability control of the distributed drive electric coach is greatly differed with the traditional coach,it is necessary to study its stability control of driving process.We will study the stability control and torque distribution of the triaxial hub electric drive coach issues in this paper.Based on one type of triaxial hub electric drive coach,considering that the first and third axis driving and steering while the second axis driving but non steering,we study the distributed drive control method of the coach.Firstly,we establish a model with the consideration of yawing and lateral two degree freedoms through the vehicle dynamic analysis.Afterwards,the vehicle stability yawing moment is calculated according the direct yaw moment control method.Then,we make use of multiplier penalty function method to distribute the yaw moment and get the drive torque of each wheel.Finally,the control algorithm is verified by the simulation software Simulink and the drive force distribution is verified by the joint simulation with software Trucksim.The simulation result showed that the control algorithm can inhibit the coach from generating side slip angle excessively when the coach is in the process of movement and the yaw velocity calculated is consistent with the expected model,which showed that the control method is effective on the vehicle stability control.In this paper,we conduct a simulation analysis with the influence of the third axis steering and non steering on the motor and wheel grinding under two working conditions of step input and lane change.The result show that the wheels require less drive force with the steering third axis in a condition of other parameters in static,thus it can reduce the output torque of the motor and increase the efficiency of the vehicle.The tire adhesion rate result showed that the adhesive force on each tire is far away from the maximum value with the third axis steering,the potential of adhesive force is huge that it is hard to instability.The result showed that the control method and the drive force distribution method can be effectively applied to the control of coach stability under different speeds.