Small scale test bench based performance analysis of a fuel cell/ultra-capacitor hybrid vehicular power system with an improved power conditioning unit

For vehicular systems, fuel cells (FCs) are considered as a potential long term alternative to replace conventional combustion engines. However, high cost and slow dynamic response of FC are still the main challenges for wider applications. To overcome this problem, an auxiliary power system with adequate power capacity has to be incorporated. Ultra-capacitors (UCs) can provide an applicable solution in this aspect. Thus, a test bench of FC/UC hybrid configuration that can be suitable for vehicular systems is presented in this paper. In addition, an improved power conditioning unit (PCU) that can enhance fuel economy compared to conventional converter topologies is provided. Two different hybridization topologies are examined from different aspects. A test bench performance verification of a fuzzy logic based energy management strategy that was discussed in earlier simulation-based studies of the authors is investigated. Experimental results with small-scale devices, namely, a PEMFC (1200 W, 46 A) manufactured by the Ballard Power System Company, and four UC modules (58 F, 15 V) manufactured by the Maxwell Technologies Company, illustrate the performance analysis of both the applied PCUs and employed energy-management scheme during load cycles.