Heeyun Lee

Power management strategy of hybrid electric vehicle using power split ratio line control strategy based on dynamic programming

This paper is concerned with power management strategy of hybrid electric vehicle. Dynamic programming based power split ratio line control strategy is studied for parallel type hybrid electric vehicle to improve fuel economy performance. Dynamic programming, one of the optimization based control strategy, is powerful tool to provide optimal solution for hybrid electric vehicles power management problem. However, it is considered not implementable as real time control strategy due to its non-causal property. Recently, as global positioning systems and intelligent transportation systems facilitate the prediction of future driving cycle, power management strategy using this information becomes available. On the assumption that future driving cycle is given, power management strategy using this information is studied. Backward vehicle simulation with dynamic programming is used to extract information about optimal control policy from defined driving cycle information. The interpreted result is applied to parameter of power split ratio line control strategy. The strategy is evaluated on simulation using parallel type hybrid electric vehicle on diverse driving cycles and shows improved fuel economy performance compared with rule based control strategy.

Component size and gear ratio optimization in PHEV powertrain

A PHEV powertrain using gears instead of transmission is discussed in this paper. Because a transmission or planetary gear ratio is usually given, there is no need to consider gear ratio in component sizing process. In this case, however, gear ratios are not given. These ratios are a critical factor for fuel economy. So component sizing optimization is conducted including gear ratios. An energy management strategy is suggested based on optimization result and evaluated by forward vehicle simulation.