Optimal warm-up control strategy of the PEMFC system on a city bus aimed at improving efficiency

Proton exchange membrane fuel cells (PEMFC) are considered an ideal solution for zero-emission vehicles. This study focuses on the warm-up strategy of the PEMFC system in an energy-type power train, which is widely used on city buses. Firstly, a system model was built and validated by experimental data. Based on the model, a dynamic programming (DP) algorithm was utilized to determine a warm-up method that optimizes global efficiency. Then, a rule-based analysis was carried out and a three-step strategy based on the DP algorithm was proposed in order to satisfy the demand of real-time control. Simulation results show that the efficiency optimization of the three-step strategy is very close to that of the dynamic programming algorithm. In addition, the effects of warm-up time and environment temperature on efficiency are discussed. Results show that a longer warm-up time and a higher environment temperature are helpful for improving efficiency.