Experimental Evaluation of Supercapacitor-Fuel Cell Hybrid Power Source for HY-IEL Scooter

This paper presents the results of development of a hybrid fuel cell supercapacitor power system for vehicular applications that was developed and investigated at the Energy Sources Research Section of the Wroclaw Division of Electrotechnical Institute (IEL/OW). The hybrid power source consists of a polymer exchange membrane fuel cell (PEMFC) stack and an energy-type supercapacitor that supports the system in time of peak power demands. The developed system was installed in the HY-IEL electric scooter. The vehicle was equipped with auxiliary components (e.g., air compressor, hydrogen tank, and electromagnetic valves) needed for proper operation of the fuel cell stack, as well as electronic control circuits and a data storage unit that enabled on-line recording of system and vehicle operation parameters. Attention is focused on the system energy flow monitoring. The experimental part includes field test results of a vehicle powered with the fuel cell-supercapacitor system. Values of currents and voltages recorded for the system, as well as the vehicle’s velocity and hydrogen consumption rate, are presented versus time of the experiment. Operation of the hybrid power system is discussed and analysed based on the results of measurements obtained. 1. Introduction Hydrogen becomes a more reliable future energy carrier and its usage as fuel for fuel cells becomes a more and more probable future method for electric energy production. This statement can be supported by a large number of scientific papers that present the latest developments on fuel cell technology [1–3], innovative fuel cell stationary [4, 5], and mobile and automotive applications [6–8], as well as considerations on hydrogen economy prospects [9–11]. Polymer exchange membrane fuel cell (PEMFC) is the most promising fuel cell type for future commercialization and application. Although PEMFC has suitable parameters for the previously mentioned applications, among others low operating temperature and high current density, it cannot serve as the only energy source in the power system. Hybridization of power sources is needed to provide immediate power supply for auxiliary devices during the fuel cell start-up and to supply power during peak demands. The latter is important especially in the case of automotive applications where load changes are sudden and the power train requires an immediate power supply for a comfortable drive. There are literature reports concerning battery/fuel cell hybrid systems [12, 13]. Because the battery presents some drawbacks, such as low life cycle, long recharging