Study On Shift Control Strategy Of Pure Electric Bus With Automatic Transmission System (AMT)

The strategy of automatic shift control is a key to determine its power and economic performance and drivability with Automatic Transmission Technology (ATT), which is the core technology of AMT Automatic Mechanical Transmission (AMT) and hot area of research in the field of domestic automobile automatic transmission technology. The primary research contents include the strategies of optimum power shift control and of energy consumption economic shift control Taking a pure electric bus project on AMT as the research background, simulation modeling method is thus designed to improve the algorithm of the current optimum power shift control strategy for electric bus so as to obtain a more precise shift surface with MATLAB/SIMULINK software. The paper focuses on a three-parameter optimum economic shift control strategy that aims at motor efficiency based on a two-parameter shift control strategy and obtaining the best shift surface with the simulation modeling method. Considering the power and economic demands of vehicle, a control scheme of power and economic shift mode, or the automatic interchange, is developed and the feasibility and superiority by the vehicle test is verified.The overview of AMT development and the research status of the shift control strategy are introduced in this paper. To understand the powertrain and shift mechanism for pure electric vehicles, the key components of automatic transmission system are discussed in detail. In addition, the control process of AMT is further elaborated.In order to prove the shift control strategy for pure electric vehicles, the characteristics of motor torque are discussed. As a result, he driving equations of vehicle are derived from the dynamic analysis of vehicle. A variety of current power shift control strategies and strategy-making processes about the mapping method and the analytical method are discussed, and furthermore, some flaws of these methods necessary for a large amount of calculation and with low accuracy are pointed out. And the simulation modeling method substituted for the analytical method are proposed to develop the current optimum power shift control strategy, which not only greatly simplifies the complexity of the algorithm but also improves the accuracy of the calculation result. In order to study the energy economic shift control strategy for pure electric vehicles, the efficiency and versatility of a motor are thoroughly investigated. The two-parameter economic shift control strategy and the method of strategy-making are also discussed, and the drawbacks of the method too are pointed out. Therefore, a three-parameter economic shift control strategy area is proposed on the basis of the principle of keeping the motor run at its best.Based on these shift control strategies given above, a simulation model is established using MATLAB/SIMULINK, the best dynamic and economic shifting curved-surface and shiftpoint data surface are acquired, and then the data are saved to the AMT electronic control unit (TCU), thus creating the sufficient and necessary conditions for the implementation of a control strategy.In addition, the power and economic performances of vehicle are considered comprehensively. The paper at first takes full account of the shift lever position, the SOC value of battery, the opening and changing rates of throttle and other factors, while specifying the use of language C for programming with Code Warrior software. And in the end, a control scheme of automatically converted mode of power shift and economic shift during the running process is formulated to improve the performance of the automatic transmission for vehicles..In accordance with the relevant testing standards on the power and energy consumption economic performance in China, the acceleration test of vehicle and the consumption test of basic urban cycle (ECE-15) are to verify the feasibility of the control strategies as above. The test results show that the developed shift control strategy is feasible, with superior dynamic control performance to that of the two-parameter. The applied simulation modeling algorithm can be used to obtain higher accuracy for shift points than the analytical method, which substantially improve acceleration and energy consumption economic performances, and achieve the desired research objectives.