Optimization of the fuel economy of a hybrid electric vehicle

In this paper, we present a simulation study of the potential improvement in fuel economy that is available by optimizing the usage of the high voltage battery in a hybrid electric vehicle with the configuration of the Toyota Prius. A mathematical model of the vehicle system is proposed, and used with an optimizer to find the battery usage over a drive cycle that gives optimal fuel economy. The procedure calculates the best engine operating point for every point in the drive cycle. Thus, two levels of optimization were performed; the battery power usage over the entire drive cycle was optimized, and the system operation at each point in the drive cycle was optimized for the given conditions, including the battery usage at that point. The final battery power usage found by the optimizer is presented, along with the improvement in fuel economy.