纯电动汽车两挡AMT换挡策略研究

Shifting Strategy for Two-Speed AMT of Electric Vehicle

两挡AMT相较于单级固定速比减速器,能够降低整车系统对电池和电机性能的要求,但需要为其设计合理的换挡策略,以保证车辆经济性和动力性满足需求。首先分析驱动工况下电池、电机和变速器效率随车速和加速踏板开度的变化情况,以系统效率最高为目标,设计最佳经济性换挡策略。其次,分析不同挡位下加速度随车速和加速度踏板开度的变化情况,以加速度最大为目标,设计最佳动力性换挡策略。最后,设计了一种换挡策略切换控制器,将百公里电耗和加速时间组成综合性能指标,基于模糊理论计算动力需求因数,根据动力需求因数选择相应的换挡策略。仿真和试验结果显示:相较于传统换挡策略,平均百公里电耗降低997%,加速度略有恶化约3.96%。因此,该换挡策略在基本保证驾驶员动力需求的同时,极大地提高了经济性,可有效延长车辆的续航里程。

Compared to single fixed speed-ratio reduction gear,two-speed AMT can reduce requirements for battery and motor performance of the complete vehicle system,but reasonable shift strategy is required to ensure that requirements of vehicle economy and power can be met.Firstly,this paper analyzes changes of battery,motor and transmission efficiency under the driving condition with changes of vehicle speed and accelerator pedal opening.To realize the goal of maximum system efficiency,the paper designs an optimal economic shift strategy.Secondly,the paper analyzes changes of the accelerated speed under different shifts with changes of vehicle speed and accelerator pedal opening.To realize the goal of maximum system efficiency,the paper designs an optimal dynamic shift strategy.Finally,the paper designs a shift strategy switch controller,makes up power consumption of 100 kilometers and acceleration time into comprehensive performance index,calculates power demand factors based on the fuzzy theory,and selects corresponding shift strategy based on power demand factors.The simulation and experiment results show that compared with the traditional shift strategy,the average power consumption of 100 kilometers is reduced by 9.97%,and the acceleration is slightly worse by about 3.96%.Therefore,the shift strategy can not only ensure the driver’s power demand,but also improve the economy and extend vehicle endurance mileage.