Research On AMT Parameter Design And Shift Control Of Pure Electric Commercial Vehicles

With the promotion of electric vehicles,people are constantly increasing their demands on accelerating performance and driving range,which has led to the powertrain system becoming more gears.In this paper,a electric commercial vehicle(ECV)was analyzed to find the optimal design for the powertrain with least consumption and cost.Based on this,the shifting rules were established and the control strategies of clutch-less shift process were studied.The specific work is as follows:1)In order to find the optimal design of powertrain for ECV,the consumption and cost or ECV with one-speed,two-speed and three-speed transmission system were analyzed and compared.A motor database was built based on the method to generate torque-speed curves and efficiency maps rapidly.The speed ratio of each motor in database was optimized and a cost model was built to estimate the total cost for powertrain.The most reasonable design of powertrain was obtained through comparative and analysis.2)The best dynamic shifting schedule and the optimal economic shifting schedule were formulated with the vehicle speed and accelerator pedal opening as the control parameters.Finally,the shift speeds were optimized to find the comprehensive shift schedule which taking into account the dynamic and economic performance.3)A method of grade identification of pure electric vehicle based on the longitudinal dynamics theory of vehicle was established and its possible sources of error were analyzed in actual use.According to the characteristics that the quality of ECV changed greatly during the daily using,the starting quality correction strategy was proposed to make the final slope recognition error is less than 1%.4)According to the functional requirements of TCU,the hardware and software systems are designed respectively.Firstly,TCU hardware system is designed from the aspects of main chip selection,minimum system design and peripheral circuit design.And the underlying driver program of each function module of TCU was designed.Then TCU application-layer control software was designed based on the clutch-less control strategy.5)Built a clutch-less AMT system test platform for ECV.The inertia load mechanism was used to simulate the driving resistance of the vehicle on the road and the effectiveness of the shift control strategy in TCU was verified by AMT dynamic shift test.