Research Of Economic Shift Schedule And Development Of Controller For Pure Electric Vehicle

Under the background of energy crisis, resource shortage and severe air pollution currently, research tasks on pure electric vehicle are imminent. Most electric vehicles have a rather limited driving range because of the low capacity of the battery and the inefficient powertrain system. The thesis focuses on researching economic shift schedule for automated mechanical transmission which is equipped in pure electric vehicle. It aims to extend the vehicle’s travel distance by making the whole system consumption as low as possible when driving. Smoothness is also considered as a key index when shifting. The specific steps of research on automatic shift control method are as follows:Firstly, according to other research papers on fuel vehicle, we try to build up two-parameter shift schedule considering motor efficiency. In the process of a shift, the control system makes the vehicle acceleration equal to each other before and after shifting in order to comply with the original dynamic demand from the driver. Compare the shift strategy with the traditional one and establish dynamic shift schedule based on static shift schedule.Secondly, according to experimental data, we establish the efficiency model of the inverter, the motor and the transmission. The powertrain system energy consumption model is finally to be obtained and based on the model we figure out optimal gear ratio sequence under UDDS drive cycle to ensure high efficiency of the whole electric drive system.thirdly, the optimal gear ratio sequence is used as the learning database to realize the intelligent shift control for auto transmission. Compare both of the two shift schedules under ECE drive cycle and conclude from that comparison.Finally, conduct hardware development on auto transmission including minimum system circuit, signal processing circuit, CAN communication circuit, stepper motor drive circuit and so on. Besides, accomplish designing PCB and welding all the electronic components on PCB to get the final auto transmission controller. In the respect of software system of the controller, main program, signal acquisition program, stepper motor control program, shift control program and CAN communication program have been designed. Experiment has been conducted to test the control method based on embedded system and it also proves the whole control system is reliable. Besides, some suggestions have been put forward for future research.