A hybrid fuel cell power supply with rapid dynamic response and high peak-power capacity

Fuel cells provide clean, safe and quiet power to the users; however, one main week point of the fuel cell is its very slow dynamics. To overcome this limitation, this paper presents a hybrid power supply system that consists of three individual sources with different power-density characteristics - fuel cell, battery, and supercapacitor - which are connected to the same voltage bus through appropriate dc-dc power converters and controls. The proposed hybrid power supply features high peak-power capacity and provides fast response to the load power change, with three energy components meeting the load power demands in hours, minutes and seconds respectively. The system can automatically adjust the fuel cell current to manage the battery state of charge, vary the battery current to regulate the bus voltage by delivering or adsorbing some amount of peak power, and, if necessary, trigger the supercapacitor to supply or accept excess peak power so as to limit the battery current. This concept is verified on by numerical simulation, and simulation results show that the proposed system can rapidly respond to the load power variations and adequately meet high peak power demand of the load.