CVT型车辆经济性加速策略优化与分析  

Optimization and Analysis of Economical Accelerating Strategy for CVT Vehicles

作　　者：徐少兵[1] 李升波[1] 赵芸辉[2] 成波[1] 

机构地区：[1]清华大学汽车安全与节能国家重点实验室,北京100084 [2]北京航空航天大学交通科学与工程学院,北京100191

出　　处：《机械工程学报》2015年第12期110-119,共10页Journal of Mechanical Engineering

基　　金：国家自然科学基金(51205228);清华大学自主科研计划(2012THZ0)资助项目

摘　　要：不当的加速策略是造成车辆行驶油耗变差的重要原因,为降低加速过程油耗,通过伪谱最优控制方法定量化地研究CVT型车辆的经济性加速策略。在建立包含发动机油耗的车辆纵向动力学模型、提出消除加速距离影响的当量油耗指标基础上,将经济性加速策略的辨识构建为一个Bolza型最优控制问题。该问题的状态方程和性能指标具有强非线性,理论求解困难,因此利用Legendre伪谱法实现其数值求解,得到经济性加速度的量化表达,并进一步分析数值求解结果的形成机理。研究表明,经济性加速策略本质上是提高发动机效率和降低风阻能耗的整体协调优化;最优加速策略是与发动机特性和目标末速度密切相关的动态策略;过于激烈或平缓的加速度均会造成油耗变差。最后,仿真验证了经济性加速策略的潜在节油效果。Improper accelerating strategy is critical to deteriorate the fuel consumption of ground vehicles. In order to reduce fuel consumption during acceleration, the fuel optimized accelerating strategy of CVT-based vehicles under the framework of pseudo-spectral optimal control is studied quantitatively. The vehicle longitudinal dynamic model including engine fuel consumption is built first, and an equivalent fuel consumption index is proposed to eliminate the effect of the travelling distance. Further the identification of eco-accelerating strategy is then converted into a Bolza-typed optimal control problem. The state equation and performance index is strongly nonlinear, which makes it difficult to obtain theoretical optimal solution. So the Legendre pseudo-spectral method is adopted to obtain the numerical solution. The economical accelerating strategy is presented quantitatively and the mechanism of the numerical results is also analyzed by using differential element method. The simulation and analysis show that fuel-optimized accelerating strategy is the balance of increasing engine efficiency and decreasing air resistance, the optimal accelerating strategy is a dynamic strategy which is closely related to the engine characteristics and target end-state speed, both aggressive and mild acceleration are objectionable to good fuel consumption in accelerating process. The potential fuel benefit of the proposed strategy is evaluated by simulations.

关 键 词：车辆 经济性驾驶 加速过程 最优控制 伪谱法 

分 类 号：TP273[自动化与计算机技术—检测技术与自动化装置]