Development of robust suboptimal real-time power sharing strategy for modern fuel cell based hybrid tramways considering operational uncertainties and performance degradation

The powertrain system of modern PEMFC based hybrid tramways typically contains a PEMFC system and a hybrid energy storage subsystem when combing a lithium-ion battery (LIB) modules with a supercapacitor (SC) bank. Based on the detailed analysis of stochastic uncertainties in tramway operation, a suboptimal real-time power sharing strategy considering operation uncertainties as well as fuel economy and system durability is proposed in this paper. The proposed energy management strategy consists of three modules, namely the fundamental real-time penalty power sharing module, the fuzzy-logic based differential power compensation module, and the Rainflow-based predictive SOC balancing module. Firstly, suboptimal real-time power sharing among different energy sources is achieved in the fundamental real-time penalty power sharing module. Secondly, a fuzzy-logic based differential power compensation module is designed to achieve the performance degradation balancing between PEMFCs and LIBs. Furthermore, a Rainflow-based predictive SOC balancing module is developed to realize adaptive updating concerning key parameters of the above two modules based on historical SOC information identification of SC subsystem and enhance the robustness to stochastic uncertainties. Detailed simulation results demonstrate that the proposed energy management strategy can guarantee operation stabilization of PEMFC based hybrid topologies throughout the simulated driving cycle. The influence of the proposed energy management strategy on the service life of the PEMFC subsystem and fuel economy of hybrid tramway is discussed in detail. Finally, the proposed energy management strategy with optimized PEMFC and HESS both decoupled topology is verified to be more suitable for PEMFC-based hybrid tramway applications with minimum equivalent hydrogen consumption and performance degradation balancing among hybrid energy sources, compared with other reductant hybrid configuration-based energy management strategies.