并联混合电动车辆采用无级变速器速比控制对燃油经济性的改进

考虑到并联混合电动车辆(HEV)动力系响应滞后,建议采用无级变速器(CVT)速比控制方法来实现HEV的燃油经济性的改进.在该方法内,由估算于动力系响应滞后之后根据车辆速度来修正目标CVT速比,并推荐一个加速图谱来估算响应滞后的车辆速度.该CVT速比控制方法采用HEV台架试验机试验证实.根据试验结果,可以看到用修正速比控制方法发动机工作迹线比用常规CVT速比控制对于适度加速模式可以有更有效换档范围,故能给出最佳的燃油经济性.此外,还采用HEV动力系模型对联邦城市驱动计划性能仿真进行估算响应滞后对燃油经济性的影响.仿真结果表明作为响应滞后采用修正CVT速比增大可以实现最佳的燃油经济性.但在实际应用中,要求最佳燃油经济性和加速性能之间进行折衷.

Improvement In Fuel Economy For A Parallel Hybrid Electric Vehicle By Continuously Variable Transmission Ratio Control

A continuously variable transmission(CVT) ratio control algorithm is proposed to achieve the improved fuel economy of the parallel hybrid electric vehicle (HEV) by considering the HEV powertrain response lag. In this algorithm, the target CVT ratio is modified by the vehicle velocity that is estimated after the powetrain response lag. To estimate the vehicle velocity after the response lag, an acceleration map is suggested. The CVT ratio control algorithm is validated by the HEV bench tester. From experimental results, it is found that the engine operation trajectory by the modified ratio control algorithm is shifted to a more efficient region compared with those by the conventional CVT ratio control for the mild acceleration mode, which gives better fuel economy. In addition, performance simulations for the federal urban driving schedule are carried out to evaluate the effect of the response lag on the HEV fuel economy using the HEV powertrain model. The simulation results show that a better fuel economy can e achieved as the response lag used in the modified CVT ratio increases. However, in actual applications, a compromise between the fuel economy and the acceleration performance would be required.