无级变速器车辆经济性巡航策略的伪谱法优化

摘要

The fuel consumption of passenger cars not only associates with their fuel-saving performance, but also depends on how they are driven. This paper investigates the economical cruising strategies for vehicles equipped with continuously variable transmission (CVT) and gasoline engine. A fuel optimized control problem is formulated after building models for vehicle longitudinal dynamics and engine fuel consumption. This is a typical singular optimal control problem with a nonstrictly convex cost function, so the Legendre pseudo-spectral method is selected to obtain its optimal solutions. The results show that vehicles should cruise at a constant speed (CS) when the average speed is either low or high; while the‘pulse-and-gliding’(PnG) strategy becomes more economical when the average speed is medium, the maximum fuel saving of PnG is 13%higher than that of the CS strategy. For the PnG strategy, the fuel-saving mechanism and the relationship between fuel economy and driving comfort are also explained.%汽车行驶过程中的油耗不仅同车辆自身性能相关，也取决于驾驶员的操作方式。本文研究了装备无级变速器和汽油发动机的车辆的经济性巡航策略。首先建立了车辆纵向动力学模型和发动机油耗模型，将经济性巡航策略的辨识构建为一个最优控制问题。该问题的性能函数呈现高阶非线性且存在凹弧段，是一个典型的奇异最优控制问题。因此采用Legendre伪谱法进行求解。结果显示：当平均巡航速度较低或较高时，应采取匀速(CS)行驶策略；当中速时，“加速滑行”(PnG)策略更为经济，相对匀速策略最大节油率达13%。最后探讨了PnG策略的节油机理、经济性与舒适性的关系。