L. Palma, M. Harfman-Todorovic, P. Enjeti, Sewan Choi“Analysis of DC-DC Converter Stability in Fuel Cell Powered Portable Electronic Systems”
Abstract : Fuel cell is an emerging power source for portable load), it is necessary to stack many in series to obtain a
electronic systems. The steady state DC output of a fuel cell reasonable output voltage.
suffers from a 2 to 1 voltage variation from no load to full load.
A boost type DC-DC converter is employed to generate a
regulated output voltage. The internal impedance of the fuel
cell consists of a membrane resistance Rm, and two parallel
resistor/capacitor (Rp1-C1 ; Rp2-C2) elements related to the
electron transport phenomena in the anode and cathode. It is
shown that this internal impedance can influence the dynamic
response of the DC-DC converter, often in a manner that _
degrades regulator performance. In this paper the effect of the
fuel cell internal impedance on the dynamic performance of the
power converter is fully analyzed. Design inequalities are
reviewed in per-unit quantities to better understand the
interaction between the converter, fuel cell and potential
instability conditions. An approach to utilize supercapacitors to
enhance stability and improve dynamics is explored. A method
to calculate the value of the supercapacitor required is also X
detailed. Finally, experimental results obtained on a 30W PEM Fig la An example 30W portable fuel cell system
fuel cell system powering a DC-DC boost converter are
discussed in detail.