Research On Torque Coordination Control Strategy Of In-wheel Drive Extended Range Electric Bus

As the best technical solution to solve the problem of the electric vehicle’s driving range, the extended-range electric vehicle has a broad application prospect. Compared with the centralized drive electric vehicle, the in-wheel motor drive electric vehicle has become a new development direction because of its fast response, high controllability, and simple structure and so on. In this paper, the research object is the in-rear-wheel drive extended range electric bus. The vehicle energy management control and torque coordination control strategy are studied based on the theory of vehicle system dynamics to achieve the dynamic and economic control of the extended range electric vehicle and to meet the requirements of vehicle handling and stability at the same time. The main research contents and conclusions are as follows:First, according to the characteristic of the power system of in-wheel motor drive extended-range electric vehicle,and to ensure the vehicle power and economy as the goal, the performance parameters of the driveline system, the driving motors, the Auxiliary Power Unit (APU) and the power battery were calculated.Secondly, This paper established a 15 degrees of freedom vehicle dynamics model in AMESim based on the theory of vehicle multi-body dynamics, including the vehicle longitudinal, lateral, vertical motion, body pitch, roll and yaw motion, vehicle steering and rotary motion, vertical motion of four wheels. And combined with the traditional vehicle dynamic model and the dynamic analysis model of the electric vehicle, the modularized dynamic simulation model of the in-wheel drive extended-range electric bus is established.Then, the constant power vehicle energy management control strategy and braking energy recovery control strategy are established based on the characteristics of gas-electric extended-range electric bus to improve the economy of the vehicle, and the validity of the model is verified by the experiment.The in-wheel drive steering differential control strategy has been researched. And considering the influence of the axle load transfer and the tire side slip, the steering differential control strategy which based on the modified vehicle steering model combines the torque distribution with slip ratio control of driving wheel to adjust the torque of driving motors.Finally, The Acceleration Slip Regulation (ASR) control and torque coordination control strategy have been researched. The strategy determines the best slip rate based on the real-time road identification method to restrain the excessive slip of the wheel and ensure the dynamic performance of the vehicle as the priority. And it coordinates the torque of driving motors according to the slipping condition of the wheels to adapt to various road conditions and extreme working conditions with good handling stability.