| In the context of environmental problems and energy crisis increasingly sharp,pure electric vehicles which use clean energy have been recognized as one development direction in the future of the car.With the attention of the major automobile enterprises and research institutions,as well as the support of relevant policies,the development of pure electric vehicles have a bright future.However,with the consumer's requirements about the car's performance continuous improving,the traditional single-motor-driven pure electric vehicle can't be widely promoted due to the problems of poor dynamic performance,shortly driving range and lack of driving comfort.Therefore,in the existing battery and motor technology conditions,exploit a new drive system,and research relevant control strategies to enhance the comprehensive performance of pure electric vehicles is an urgent need for the development of the electric vehicle technology.For the above needs,this paper based on Chongqing foundational science and frontier technology research special subject(project number: CSTC2015jcyjA60005)"The design theory and control method of pure electric vehicle power transmission system based on dual motor driving",regard the multi-power source coupling drive technology as the core,focus on a dual motor power transmission system(DMPTS).The following aspects of the research have been carried out:(1)With analyzes the energy-saving potential of the multi-power coupling technology and the coupling mechanism of the dual-motor torque / speed coupling and in order to fully realize the advantages of the multi-power source coupled-drive system,a dual-motor coupled drive system with four drive modes is proposed.The working characteristics of the system are analyzed by using the method of bond graph theory,and the corresponding dynamic model is established.Considering the limitation of vehicle dynamic performance and economic performance requirements,combined with the statistical analysis of high frequency range under typical cyclic conditions,the parameters of each component of the system are preliminarily determined.(2)Through establishing the system efficiency model,the efficiency of the four driving modes are calculated respectively,and the boundary of each mode is obtained by projecting the efficiency surfaces of each mode,therefore the recognition logic based on the rules is made.Following the principle of optimize the system efficiency,the motor power distribution strategy is determined.At the same time,considering the influence of the rotational inertia in the driving process,the motor output torque compensation control strategy and the motor speed control strategy are proposed respectively.(3)In order to improve the smoothness of the system work,solving the problem of the impact when drive mode switch.The switching process of each mode is studied,and the mode switching process without power interruption is worked out.The sub-process which produce impact is analyzed and the mode switching control strategy is put forward.The validity of the control strategy is verified by modeling and simulation.(4)The vehicle model and the dynamic simulation model are established based on the drive control strategy.The dynamic and economic indexes are used as the multi-objective function,the parameters of the drive system are optimized by genetic algorithm.It is proved that the vehicle dynamic and economy performance are improved through optimization,and the dual motor electric vehicles has better performance than the traditional single motor drive vehicle. |
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