Research Of Control System For 2-speed Amt Applied In Small Pure Electric Vehicle

Recent years,problems like the exhaustion of fossil energy and the deterioration of environment have becoming increasingly prominent.Under this background,pure electric vehicle(PEV)has been attractting great attention among research institutes around the world with the advantages like energy-saving and zero-emission.However,almost all PEVs on the road are equipped with only a fixed-ratio gearbox,which cannot guarantee the balance of vehicle’s performances of start-up,acceleration and maximum speed under the same power motor.Meanwhile,a fixed-ratio gearbox cannot help with the optimization of the motor’s working point,either.Therefore,a 2-speed automated mechanical transmission(2AMT)for PEV is proposed and developed to balance and improve the described vehicle’s performances in lower motor cost and optimize the motor’s working point to its high efficiency range,and then help with PEV for its better development.Based on a small PEV,the research and development of this 2AMT system is carried out in following aspects.Firstly,according to the proposed mechanical structure,the overall parameters of this 2AMT’s powertrain system like power motor,battery and gear ratios are calculated and matched.And the performances of PEV equipped with 2AMT and a fixed-ratio gearbox are testified respectively and compared with each other in the vehicle model established in MATLAB/Simulink.Results show that PEV equipped with 2AMT has a better performance.Then,the control system for this 2AMT is developed to realize the proper gear-shifting process automatically.On the one hand,the economic gearshifting schedule in related with driver force demand is proposed to determine the gear-shifting time in a good performance.Also,the control strategy for power motor and transmission is proposed respectively and the logic relation between them is described,which compose the whole gear-shifting control strategy for this system.On the other hand,the hardware and software of this2AMT’s transmission control unit(TCU)is developed by module-based design method to carry out the proposed gear-shifting schedule and control strategy.Lastly,the test bench is designed and built to verify the 2AMT’s operation performance,the TCU’s feasibility,gear-shifting schedule and the whole gearshifting control strategy.The result shows that the designed 2AMT and its control system can realize the proposed gear-shifting schedule and control strategy,and finish the automatic gear-shifting process properly.Above all,based on the results from simulation and test bench,the 2AMT and its control system developed in this paper can be a great benefit to improve PEV’s dynamic and economic performances in lower motor cost,which offers many experiences for futher research of PEV’s powertrain system.