Fuel-optimal combined driving strategy and energy management for a parallel hybrid electric railway vehicle

A fuel-optimal operating strategy is proposed for a parallel hybrid electric railway vehicle that involves both a modification of the driving strategy and a corresponding energy management. The optimisation is based on an algebraic inverse system model describing the longitudinal dynamics and the complete power train. Aiming at a small computing time, only the dominant effects of the train longitudinal dynamics are taken into account in the control-oriented model. Using Bellman´s optimality principle, a fuel-optimal strategy is derived that adapts both the driving strategy and the power management strategy. Here, the ideal case is assumed without any disturbances affecting the train operation. Simulation results of the proposed optimisation strategy are given and compared to the fuel consumption of a conventional diesel railway vehicle.