The Study Of Matching Calculation And Emulating Of Powertrain And Speed-ratio Base On The MPV Equipped With EM-CVT

This thesis is aimed to discuss Multi-Purpose Vehicle(MPV) equipped with Electro-Mechanical Continuously Variable Transmission(EM-CVT). Type selection and matching of transmission system are made on account of this MPV. Meanwhile, The Transmission efficiency experiment of EM-CVT is made. The regularity for change of speed-ratio based on optimal economic performance and optimal power performance is the main research object.Matching calculation of transmission system(include engine, electric-motor, CVT,battery etc)for PHEV is made in this thesis, thus determining each subsystem of the transmission system. In order to providing the data support for subsequent analysis, article proceeds the bench test research of EM-CVT transmission efficiency, and analyses it under various input speeds and speed-ratio, thus obtaining the average efficiency of CVT transmission.The three running models of PHEV consist of the pure engine drive mode, pure electric drive mode and hybrid drive mode. Optimal economic conditions of the constant power curve are used as the optimal operation condition in the pure engine drive mode,pure electric drive mode. However, The CVT ratio matching is related with the energy management strategy in the hybrid drive mode, this article analyses two different conditions to confirm the target ratio, one of them aimed to search the highest efficiency point of engine; another aimed to search the highest efficiency point of whole power source. The CVT target ratios in different driving modes are calculated based on the velocity of the PHEV and characteristics of engine and electric-motor.In this article, three vehicle simulation models(pure engine vehicle, pure electric vehicle and PHEV) are established by the AVL Cruise to validate the rationality of the CVT ratio. However, the control strategy is made by MATLAB/Simulink/Stateflow, then established united simulation model combine with Cruise. The economy performance of the PHEV based on the MPV is simulated by using the New European Driving Cycle(NEDC),and make a comparison of the economical efficiency obtained by these two different target ratio under the hybrid drive mode. The result of the emulating indicate the CVT target ratio of the pure electric drive mode, charge drive mode and the hybrid drive mode are reasonable. The engine and motor work at the target conditions. The fuel saving ratio of the PHEV greater than the demand asked primly.