SUPERCAPACITORS FOR PEAK-POWER DEMAND IN FUEL-CELL-DRIVEN CARS
A downscaled drive train with a 6.5 kW fuel cell and a 10 kW supercapacitor module was realized and tested. The voltage levels and the energy flow between fuel cell and supercapacitor were controlled by an electronic unit. The combined fuel-cell/supercapacitor drive train was tested with a modified New European Driving Cycle (NEDC). The 60 V, 60 F supercapacitor module consisted of 2 x 24 capacitors in series having a capacitance of 800 F each. The capacitors had a max. specific energy of 2.75 Wh/kg and a max. specific power of 6.5 kW/kg. An active electronic unit managed voltage balancing among the 24 capacitors in series. The capacitor module had a max. total energy of 30 Wh and a total max. power of 45 kW and could deliver 10 kW over a period of 6 seconds. It was demonstrated that a supercapacitor is an energy storage device that can be used efficiently in vehicle applications for recuperating braking energy and boosting peak power.