Research On Electric Vehicle Powertrain Matching And Global Optimization

Recent years,a lot of automobile enterprises pay more attention to developing new energy vehicle,especially about Electric Vehicle(EV).As the bottlenecks of key technology of EV are still exist,how to solve the driving range and battery charging problems are still unsettled.The main objective of massive international scholars is that how to match powertrain parameters of EV properly and improve the driving range and dynamic property as possible when the electric quantity of the battery is fixed.This paper has analyzed the mechanics models and the computing method of the dynamic property and the economic property of the EV and analyzed the influence of the vehicle parameters and motor rated parameters on vehicle properties.And then this paper has explained the design methods of powertrain system(motor,drive system,battery pack),and matched a low-speed EV and a high-speed EV on the basis of this method,as the objects of the research.Optimizing the initial designed powertrain parameters could improve the properties of EVs obviously.Common matching optimization methods consider the parameters of the motor is fixed,only optimize the parameters of the drivetrain,which ignores the parameters of the motor’s influence on the vehicle properties.So,this paper puts forward a powertrain optimization method which optimize both motor parameters and drivetrain parameters of the EV globally.The optimization method build the efficiency model which efficiency map depend on the motor parameters.And the global optimization takes of the specific power and the constant power expansion coefficient of the motor and speed ratio of the transmission as variables,and uses multi-objective optimization and Genetic Algorithm to optimize the powertain parameters of EV.Then,this paper optimized the parameters of a low-speed electric car and a high-speed electric car and a electric bus using the common optimization and the global optimization method,and built the simulation models of the three types of EV using ADVISOR,and compared the vehicle property of before and after the optimization and the two optimization methods.The results show that the dynamic property and the economic property of three types of EVs has improved compared with the common optimization method and the origin vehicle parameters in different extent,which indicated that the global optimization of the powertrain system is feasible,and optimization method this thesis has put forward has a reference significance to the matching of motor when designing EVs.