The Study Of Control Strategy Of Powertrain Of Electric Vehicle Equipped With Electro-Mechanical Continuously Variable Transmission

In recent years,the seriousness of the problem of excessive energy consumption and environmental problems such as the haze and greenhouse effect has increased.However the electric energy what electiric vehicle use is pollution-free and renewable.If we use EV instead of ICE Vehicle which release enormous tail gas and consume a lot of oil,the issues above-mentioned can be totally resolved.As the research subject of this article,EM-CVT has no hydraulic system and more efficient than conventional CVT,as a result,it is more suitable for equipping in EV.In powertrain control Strategy of conventional EV,only the motor keep working at optimum working areas without considering the condition of CVT.But the efficiency range of CVT is 75%?95%,the efficiency can not be ignored.So we have to consider the driving motor and CVT as a whole when when we make control strategy to make the whole work at optimum working areas.To achieving better performance of the EV equipped with EM-CVT,this artile has make a appropriate control strategy and a control algorithm through Study of Control Strategy of Powertrain.Concrete research content is as follows.This article has studied the composition and various kinds of structure forms of the EV drive system.And an improved traditional drive system has been chosen as the present layout forms EV's powertrain.Then,The classification of the motor drive system is studied and the asynchronous motor drive system was selected as the present drive system of EV in this article.In this artile,after the study of the principle and structure and advantages of technical of the EM-CVT,we have concluded that EM-CVT is very suitable for EV.This artile describes the selection and control methods of adjustable-speed motor,finally we select the DC motor as the adjustable-speed motor of EM-CVT speed motor.The EM-CVT mathematical model was established.In order to satisfy the power performance under acceleration state and the economy under steady state at the same time,we have designed a ratio control which considers the power performance and economy at the same time.Making a control strategy based on the best optimum efficiency of motor and a control strategy based on the best optimum efficiency of power system.Vehicles in different drive conditions will use different strategies.so we have made two different control strategy so that we can ensure the control strategy based on the best optimum efficiency of system has a higher efficiency than the control strategy based on the best optimum efficiency of motor.Finally,designing an improved PID ratio control algorithm to ensure the ratio has smooth change.Researching and making the bench test plan of motor and its controller and EM-CVT.We can make powertrain's control strategy through the experiment data.The simulation model of EV equipped with EM-CVT was built throught the Matlab/Simulink software.Simulation results indicate that the vehicle simulation model is right,the powertrain's control strategy is Effective,reliable and meaningful.EV use the control strategy based on the best optimum efficiency of system has a higher efficiency than EV use the control strategy based on the best optimum efficiency of motor.