ABSTRACT The shift quality of two-speed planetary of electric vehicle is closely related to the characteristics of shift oil pressure. In this paper, the smooth shift control strategy of electric vehicle with two-speed planetary transmission is studied. Firstly, the dynamic models of the two-speed planetary gear train, the shift oil pressure of the hydraulic system and the clutch friction torque are established. The analysis results show that there are three jerks during the shift process, of which the shift jerk during the clutch/brake engaging process is most obvious, thus a six-stage shift control scheme is proposed. The shift jerk degree is constructed as an optimal control problem during the clutch/brake engaging process, of which the performance function presents higher order nonlinearity. Then the optimal oil pressure trajectory is obtained by using the Radau pseudo-spectral method and the sliding mode variable structure controller of oil pressure is designed. The HIL simulation results show that by optimising the control, the degree of shift jerk is reduced by approximately 60% during the clutch/brake engaging process; and the shift oil pressure can track the optimal trajectory better and stably, the real-time and validity of the shift optimisation strategy are verified.

中文翻译：

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电动汽车两档变速器平稳换档控制策略的伪谱优化

摘要 电动汽车两档行星齿轮的换档质量与换档油压特性密切相关。本文研究了两档行星变速器电动汽车的平稳换档控制策略。首先，建立了两档行星齿轮系、液压系统换挡油压和离合器摩擦力矩的动力学模型。分析结果表明，换挡过程中存在3次急动，其中离合器/制动器接合过程中的换挡急动最为明显，因此提出了六级换挡控制方案。换档急动度被构造为离合器/制动器接合过程中的最优控制问题，其性能函数呈现高阶非线性。然后利用Radau拟谱法得到最优油压轨迹，设计油压滑模变结构控制器。HIL仿真结果表明，通过优化控制，离合器/制动器接合过程中的换档急动度降低了约60%；换档油压能更好、稳定地跟踪最优轨迹，验证了换档优化策略的实时性和有效性。