FUEL CELL SYSTEM COMPRISING AN EJECTOR FOR RECIRCULATING OFF-GAS FROM A STACK

The fuel cell system includes: - at least one fuel cell adapted to generate electrical energy from a fuel gas and an oxidizer gas; - a fuel feed duct (11) provided for supplying the fuel cell with fuel gas, the fuel feed duct including an upstream part (11 A) and a downstream part (11B); - a Venturi effect ejector (113) including a high pressure inlet (233), a low pressure inlet (238) and an outlet (240), the upstream part of the fuel feed duct being connected to the high pressure inlet of the ejector and the downstream part extending between the ejector outlet and the fuel cell; - an off-gas recirculation duct (11 R) extending between the fuel cell and the low pressure ejector inlet (238) so that, in the presence of a stream of fuel gas coming from the upstream part of the fuel feed duct (11 A) and passing through the ejector (113), the ejector draws up off-gas from the recirculation duct and ejects it into the downstream part (11 B) mixed with the stream of fuel gas coming from the upstream part; - a control circuit (15) and a valve (110) arranged in the upstream part (11A) of the fuel feed duct and arranged to be controlled by the control circuit, the valve being adapted to be placed in an open state, in which it lets the stream of fuel gas from the upstream part pass through the ejector (113), or in a closed state, in which no stream of gas from the upstream part can flow through the ejector. characterized in that said control circuit (15) is arranged to place the valve alternately in the open state and then the closed state, so that the stream of fuel gas passing through the ejector (113) is intermittent, being frequency and/or pulse width modulated by the control circuit.