Patent ID: 7442457

Claim:
A method for the operation of a fuel cell system, comprising: providing a plurality of fuel cells combined together to form a fuel cell stack, each said fuel cell having an anode, a cathode and a membrane arranged therebetween and said fuel cell stack having an anode side with an inlet for a fuel and an outlet for non-consumed fuel and exhaust gases arising at said anode side as well as a cathode side with an inlet for a gaseous oxidizing agent such as air and an outlet for exhaust gases which arise at said cathode side; providing a compressor having a compressor inlet and a compressor outlet connected to said inlet for a gaseous oxidizing agent provided at said cathode side; providing a gas dynamic pressure wave machine having a driven rotor with a plurality of chambers; supplying said exhaust gases which arise at said cathode side to an inlet of said gas dynamic pressure wave machine, wherein at least a portion of the exhaust gases is directed into the chambers of the rotor; introducing fresh oxidizing agent into said chambers of said rotor, wherein the fresh oxidizing agent is humidified by the exhaust gases in the chambers; compressing said fresh oxidizing agent and the portion of the exhaust gases introduced into said chambers of said rotor by pressure waves originating from said exhaust gases which arise at said cathode side so that the exhaust gases simultaneously drive the rotor and humidify the oxidizing agent; leading said compressed fresh oxidizing agent to said compressor inlet; expelling exhaust gases which arise at said cathode side and are contained in said rotor out of gas dynamic pressure wave machine by pressure waves propagating in said chambers of said rotor and using a control connected to a pressure retaining valve to determine an operating pressure at said cathode side of said fuel cell stack and to thereby adapt a behavior of said gas dynamic pressure wave machine in dependence on operating parameters of said fuel cell system; controlling a speed of rotation of a motor which drives said rotor of said gas dynamic pressure wave machine in accordance with a power yield of the fuel cell system; and controlling a transmission ratio of a controllable transmission provided between said rotor of said gas dynamic pressure wave machine and said motor driving said compressor in accordance with a power yield of said fuel cell system.