Optimal sizing of fuel cell hybrid electric Heavy-Duty tractor with minimum of unit mileage cost

This paper proposes an optimal hybrid energy sources sizing methodology for fuel cell hybrid heavy-duty tractors (FCHHT) comprising fuel cell system (FCS) with battery (B) and supercapacitor (SC) as hybrid energy storage system (HESS). For this purpose, an objective function of unit mileage (10⁴ km) cost (UMC) is put forward to evaluate the system's initial cost, degradation cost, and hydrogen consumption cost. Furthermore, an average power and state of charge (APS) based Energy Management System (EMS) is proposed, where power-split strategy of FCS and HESS is given, and the output power of FCS is smoothed by the average power of drive cycle power demand, the power of maximum efficiency point and maximum power of FCS, and SOC of HESS. Finally, to solve the hybrid energy source optimization problem, the cancer cell competition and metastasis algorithm (C3MA) is proposed, where an efficient population position updating strategy is used to simulate the competition and metastasis of cancer cells, and the search space can be explored more effectively. C3MA is evaluated using six benchmark functions, demonstrating its robustness and rapid convergence in high-dimensional problems. The size optimization of a 49-ton tractor was conducted. The optimum can always be achieved using APS EMS in conjunction with C3MA, Particle Swarm Optimization (PSO), and Grey Wolf Optimization (GWO). In comparison to discrete wavelet transform (DWT) EMS, APS demonstrated a 16 % reduction in UMC and a 77 % increase in lifespan. Compared to FCS + B configuration, FCS + B + SC reduces UMC by an average of 19 %.