Real time energy management strategy for a fast charging electric urban bus powered by hybrid energy storage system

In this paper, an innovative real time energy management strategy design approach is proposed for a fast charging electric urban bus with hybrid energy storage system composed of conventional batteries and supercapacitors. After modeling, a multi-objective optimization problem taking into account cycle life of the battery, total energy consumption and specific requirement that minimizing the use of battery is formulated. A quantifiable evaluation model is firstly derived to evaluate different kinds of strategies. Then a conventional fuzzy logic control based energy management strategy with features of intelligence and adaptability is proposed, but the simulation result shows that even after long time tuning it can not achieve the desired result with the manual set membership functions. Thereafter, an optimal energy management strategy based on dynamic programming is developed as a benchmark to see the room for improvement. Finally, an innovative model in the loop optimization approach based on genetic algorithm is proposed to optimize the membership functions of the conventional fuzzy logic based energy management strategy. Simulation results demonstrate that the overall performance of optimized fuzzy logic based energy management strategy can be improved significantly and can even approach the optimal results of dynamic programming.