Efficiency maximization of fuel cell electric bus using asymmetric multi-stack fuel cells.

Fuel cell electric vehicles (FCEVs) have been widely studied as alternative ecofriendly vehicles based on multi-stack fuel cell (MFC) systems. An MFC system has the advantages of considerable efficiency, reliability, and durability compared with a single-stack fuel cell system. In this study, a novel MFC concept with an asymmetric structure is proposed to maximize the efficiency of a fuel cell electric bus (FCEB). The proposed concept was designed with a cascade electrical architecture composed of differently rated power stacks, and the optimal energy distribution between the stacks was determined to leverage the asymmetric structure. This facilitates the use of high-efficiency areas of the fuel cell stacks throughout most of the output power range. To confirm the performance of the proposed mechanism, dynamic programming, a global optimization technique, was used as the energy management strategy, and the FCEB was tested on Manhattan, Hanoi, and Seoul bus driving cycles. As a result, a significant reduction in the total fuel consumption of the proposed MFC electric bus compared with that of the conventional FCEB was verified.