Abstract:

Aiming at the life decay of proton exchange membrane (PEM) fuel cells in fuel cell/Li battery/supercapacitor hybrid energy storage streetcars during dynamic loading, start-stop cycle, idling cycle, and high-power operation, an energy management strategy combining the Pontryagin's minimum principle(PMP) of very small value and durability was proposed. The start-stop control strategy controlled the start and stop of the fuel cell, effectively reducing the number of fuel cell starts. The joint cost function was constructed using the overall hydrogen consumption of the energy storage system as the economic cost and the fuel cell performance degradation index as the durability cost. The online adaptation of the covariance variable with the real-time change of charge state was realized under satisfying the desired conditions. The proposed strategy was simulated and compared with the traditional minimal value strategy and state machine strategy. The results show that the proposed strategy under the urban cycling condition reduces the peak current by 33.2% and hydrogen consumption by 12.50% compared with the traditional Pontryagin strategy fuel cell; the proposed strategy under the suburban cycling condition reduces the peak current by 21.88% and hydrogen consumption by 40.39% compared with the traditional Pontryagin strategy. The proposed management strategy has good adaptability under different working conditions, solves the shortcomings of traditional PMP that can only be applied offline, controls the number of start-stop at a low level, and has the ability to extend the life of the fuel cell.

Key words: hybrid tram, Pontryagin's minimum principle(PMP), proton exchange membrane (PEM) fuel cell, durability