| Distributed electric drive vehicle provides a new solution for reducing energy consumption.As the core driving component of the distributed electric vehicle,electric wheels usually adopt single motor with reducer or motor direct drive configuration,but these configurations cannot guarantee the high-efficiency operation of the vehicles in a wide range of torque and speed.In order to improve the driving efficiency of distributed electric vehicles and expand the efficient operating region,this paper proposes a new type of layered coupling electric driving configuration,and this configuration is composed of the front and rear axle torque coupling in the upper layer and the dual-motors speed coupling in the electric wheel in the lower layer.In view of this configuration,this paper focuses on the following researches:(1)This paper analyzed the working principle of the layered coupling electric drive configuration,and determined the working mode of the configuration,and then probed into the mechanism of the efficient zone expansion of the configuration.Based on the analysis of power flow of different driving modes,the bond graph model of each mode was established.Finally,the dynamic and steady mathematical models of each driving mode are derived from the bond graph model.(2)When the electric wheel is driven by a single motor,the vehicle efficiency is linearly mapped to the efficiency of the motor.Through efficiency optimization,the equivalent MAP characteristics of the electric wheel in dual-motors speed coupling drive mode were obtained.On this basis,the equivalent MAP characteristics of each electric wheel and the boundary of each mode area were determined according to the global efficiency optimization method.Based on the equivalent MAP characteristics of the electric wheel,the optimal equivalent MAP characteristics of the whole vehicle were obtained by using global efficiency optimization method.Formulated the boundary of each mode area,and then a frequency control method of mode switching was introduced.On this basis,this paper developed an efficient and accurate mode identification strategy.Finally,based on the principle of energy efficiency optimization,the power distribution strategy of the layered coupling electric drive system was developed.(3)The forward simulation model was built to verify the energy saving characteristics of the distributed electric drive vehicle.The typical drive cycles were analyzed,on this basis,the driver model was designed and the vehicle demand torque was obtained.Built the mode identification model,power distribution model and planetary reducer model of the layered coupling electric drive system.The distributed electric drive vehicle model was established by utilizing the Carsim software,and the co-simulation analysis of vehicle energy efficiency test under various drive cycles was carried out on the Simulink-Carsim platform.(4)Based on the dynamic mathematical model of layered coupling electric drive,a control method of dual-motors speed coupling drive mode in the electric wheel was analyzed,and the coordinated control strategy aiming at reducing the impact of the whole vehicle was introduced.This paper analyzed the switching process among the modes in the electric wheel,and reasonably controlled the action of each actuator to complete the mode switching.Simulink was used to establish the dual-motors speed coupling drive model,and simulation results verify the effectiveness of the mode switching process control and the coordinated control method of the two motors. |
PDF Full Text Request