The current global warming situation has risen new trends to decarbonize the transportation sector. These research trends have led to an increasing interest in fuel cell systems (FCS) and their application to the light commercial vehicles (LCV). Currently, there needs to be a clear consensus in the industry about the FCS-based powertrain design for LCVs. Thus, the main target of this study focuses on understanding the influence of the propulsive system architecture in LCVs in terms of performance, durability, and environmental impact. To achieve this objective an LCV virtual model has been developed. It consists of different submodels integrated into MATLAB R2022a Simulink and GT-Suite platforms. The driver, the vehicle mechanical components, the battery and the e-motor are developed in GT-Suite, while the FCS is based on a MATLAB model that has been calibrated with experimental data from the Toyota Mirai FCV (model year 2017) obtained from Argonne National Laboratory. The durability of the FCS is estimated by means of a semi-empirical FC degradation model. Finally, the best performance of each architecture is ensured by means of an optimal energy management strategy (EMS) based on the Pontryagyn Minimum Principle (PMP), which can provide the optimal consumption given a driving cycle and a powertrain architecture. Finally, the life cycle emissions are analyzed by using data provided by GREET and GaBi. The performed study comprises the evaluation of the range-extender, mid-power and full-power FCS architectures for LCV using the developed platform and a standard LCV driving cycle, the WLTC3b. This analysis has led to the understanding of the benefits of each powertrain. In the charge-sustaining mode, hydrogen consumption is lower in the full-power design because the FC works under lower current densities. In terms of overall efficiency, combining charge-sustaining and charge-depleting modes, the range-extender and the mid-power cases provide better results. When comparing durability, this study confirms that the size of the FCS impacts degradation, the bigger the FCS in terms of power, the lower its degradation. Finally, the emissions study shows that the results are very dependent on the energy mix and the H2 production pathway. This study analyses 3 different powertrains for LCVs. However, the chosen designs are just a representative architecture for each one of them and do not consider the wide variety of existing design options. Furthermore, the possible architectures should be tested depending on the specific application of the vehicle, with a realistic driving profile different from a standardized WLTP cycle. In addition, the study of the viability of any technology requires not only an emissions study but also a cost assessment to understand the role of each of the selected architectures in the market. In previous works, the authors focused on a single powertrain architecture for heavy-duty vehicles or passenger cars. Thus, the novelty of this study relies on the integration of several designs to understand the possible FCS options for LCVs. The relevance of this study also comes from the level of detail of the analyses of the results in terms of consumption, durability and environmental emissions. This level of detail is very beneficial for manufacturers when trying to understand which architecture would be better to optimize their FCVs while following the current decarbonization trends of the sector. The performed study allows a detailed understanding of the possible FCS-based powertrain architectures. The performance and durability analyses are of high value for possible manufacturers in the transportation sector to identify which would be the best propulsive system design. In addition, the environmental impact study helps to understand the role of these different architectures in the current and future market to follow the existing decarbonization trends in transportation.
Dr.-Ing. Marcos López Juárez, Researcher, Universitat Politècnica de Valencia