Fluctuation sensitive fuel cell replenishment control means

Claim 1

A two output terminal fuel cell operative to produce a voltage output thereacross in combination with a replenishment control means for replenishing said fuel cell while said two output terminals of said fuel cell are connected across an operational load as an energy source therefor wherein said replenishment control means comprises: a saw-tooth waveform responsive differentiating network having an output voltage waveform which is substantially the derivative of the input voltage waveform, said differentiating network including capacitive means, a first relatively high impedance resistive means and a second relatively low impedancE resistive means in series connection, and auxillary means for producing a voltage drop of predetermined magnitude and polarity across said low impedance resistive means with effectively zero voltage drop across said first and second resistive means when said capacitive means is fully charged; active filter means electrically connected said series connection of said differentiating network across said two output terminals of said fuel cell, said active filter means adapted to reject substantially all frequency variations and transients in the voltage output of said fuel cell due to operational load disturbance; fuel cell reactant supply means including control means, said control means including solenoid input means adapted to supply reactant to said fuel cell when said solenoid input means is energized by current flow therethrough; voltage inverter means connected across said low impedance resistive means of said differentiating network such that said inverter means is responsive to said voltage drop thereacross, said voltage inverter means including high current on-off switching means; means connecting said high current on-off switching means of said voltage inverter means and said solenoid input means of said control means in series across said two output terminals of said fuel cell such that said inverter means is operative to control energization of said solenoid input means; said on-off switching means adapted to electrically interrupt in response to a predetermined magnitude voltage across said low impedance resistive means and to electrically conduct when said voltage across said low impedance resistive means changes in magnitude; and reset means connected to said differentiating network and operative to apply a positive voltage drop across said first and second resistive means subsequent to energization of said solenoid input means of said reactant supply means in a timed relation with respect thereto.