Power management strategy for a parallel hybrid electric truck

Hybrid vehicle techniques are widely studied recently because of their potential to significantly improve the fuel economy and drivability of future ground vehicles. Due to the dual-power-source nature of these vehicles, control strategies based on engineering intuition frequently fail to fully explore the potential of these advanced vehicles. In this paper, we will present a procedure for the design of a near-optimum power management strategy. The design procedure starts by defining a cost function, such as minimizing fuel consumption and selected emission species. The Dynamic Programming (DP) techniques are then utilized to find the optimal control actions. Through analysis of the behavior of the DP control actions, sub-optimal rules are extracted, which, unlike DP control signals, are implementable. The performance of the power management control strategy is verified by using the hybrid vehicle model HE-VESIM developed at the Automotive Research Center of the University of Michigan. A trade-off study between fuel economy and emissions was performed. It was found that significant emission reduction can be achieved at the expense of small increase in fuel consumption.