Research On The Plug In Parallel Hybrid System Based On The Electric-drive Mechanical Transmission (EMT)

The electric vehicle industry has been developed remarkably due to the inherent characteristic of energy saving and environmental protection, which would contribute to the necessity of the current energy structure changes. Being as one of the branch in the field of the Electric Vehicle, the advantages of motor have been developed and applied to the Hybrid Electric Vehicle sufficiently based on the preservation of the traditional internal combustion engine, which improve the vehicle fuel economy and emission significiantly as a result.Due to the irreplaceable advantages of cost decrease and driving distance increase compared with the pure electric vehicle, Tthere is the necessity to carry the heavy responsibility of hybrid power system research in long term run. Although the power coupling system is the key to the hybrid system, there is few breakthrough has been achieved because of the insufficient research foundation of of the auto transmission in China. The electric-drive mechanical transmission presented in the thesis solves the intractable problem of power coupling applied on the parallel hybrid system in virtue of the motor&transmission integrated technology and the rapid and accurate motor speed adjustment characteristic.The advantages and disadvantages of the different hybrid system have been discussed through the comparison within the different structures. The hybrid system configuration and distribution of the different companies have been analyzed. The Plug_in parallel hybrid system (PHS) based on electric-drive mechanical transmission (EMT) has been put forward to solve the disadvantage of the previous system. The EMT structure characteristic has been analyzed in speciality based on the explicit definition of EMT, which is to say that EMT highly integrates the engine, motor and the transmission together according to system power integration design theory to avoid the propagation errors of the connection and the position through the parts deletion. Meanwhile, the longitudinal dimension is also reduced so as to introduce the possibility to locate the parallel hybrid system fore and aft in structure.The PHS control strategy and the EMT control flow have been discussed in the thesis according to the features of the EMT. The control strategy that meets the city bus cycle has been designed to deal with the clutch transition condition of the vehicle starting and the power interrupt of the transmission shifting through the motor assistance. The passive friction synchronization of the traditional transmission will be overturned by the motor with the rapid accurate speed-regulate, the active speed-regulation synchronization technology has been introduced consequently.According to the given control strategy, the system dynamic parameter has been completed on the basis of the China city bus cycle, and the matching system static performance also has been decided to follow the dynamic performance for the electric vehicle required by the national standard. Therefore, the optimal matching parameter of the system is determined at last. According to the hybrid power system character and the matching result, the work including the conceptual design for the EMT construction, the system interface design, the lectotype design, the interface definition of the vehicle control unit, the high voltage management design and the motor controller architecture optimization have been completed in all successfully.Through the EMT characteristic analysis, and advantages and disadvantages contrasts within the present dynamometers, a high efficiency, energy saving, simple and practical test bench to drag for EMT has been put forward in the thesis, and the relevant construction and system experiment also have been completed. The experimental data show that the rapid accurate speed-regulate function of the motor allows the transmission shift time can be shortened to 0.4s, which is quite close to the DCT shift time. The research achievement is helpful to reduce the power interrupt time of the traditional AMT shift.This system has been proved to own the prominent performances both in dynamic and reliability via a large number of bench data and road test data from more than 30 sets of city buses carrying this EMT system. Especially the PHS based on the EMT has more than 50% fuel saving performance under the road test so as to achieve the target designed value.