TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The fuel cell system further includes: an oxidizer feed duct (12) provided for supplying the fuel cell with oxidizer gas, where the oxidizer feed duct includes an upstream part and a downstream part; a first and a second Venturi effect ejectors, where each of the first and the second Venturi effect ejectors includes a high pressure inlet, a low pressure inlet and an outlet, the upstream part of the fuel feed duct is connected to the high pressure inlet of the first ejector, the downstream part of the fuel feed duct extends between the outlet of the first elector and an anode side of the fuel cell, the upstream part of the oxidizer feed duct is connected to the high pressure inlet of the second ejector, and the downstream part of the oxidizer feed duct extends between the second ejector outlet and a cathode side of the fuel cell; first and second off-gas recirculation ducts, where the first off-gas recirculation duct extends between the anode side of the fuel cell and the low pressure inlet of the first ejector, and the second off-gas recirculation duct extends between a cathode side of the fuel cell and the low pressure inlet of the second ejector, so that in the presence of a stream of fuel gas coming from the upstream part of the fuel feed duct and passing through the first ejector, the first ejector draws up off-gas from the first recirculation duct and ejects it into the downstream part of the fuel feed duct mixed with the stream of fuel gas, and so that, in the presence of a stream of oxidizer gas coming from the upstream part of the oxidizer feed duct and passing through the second ejector, the second ejector draws up off-gas from the second recirculation duct and ejects it into the downstream part of the oxidizer feed duct mixed with the stream of oxidizer gas; and a first valve and a second valve that are arranged in the upstream parts of the fuel and oxidizer feed ducts respectively, where the first and the second valves are arranged to be controlled by the control circuit, and are adapted to be placed in an open state, in which they let the stream of fuel gas and the stream of oxidizer gas from the upstream parts pass through the first and the second ejectors respectively, or in a closed state, in which no gas flux from the upstream part of the fuel feed duct or of the oxidizer feed duct can pass through the corresponding ejector. The control circuit is arranged to place: the first valve alternately in the open state and then the closed state, so that the stream of fuel gas passing through the first ejector is intermittent, being frequency and/or pulse width modulated by the control circuit; and the second valve alternately in the open state and then the closed state, so that the stream of oxidizer gas passing through the second ejector is intermittent, being frequency and/or pulse width modulated by the control circuit. The first valve and the first ejector form a single part and/or the second valve and the second ejector form a single part. The opening of the first valve and/or the second valve is controlled, so that the frequency and pulse width increase when the power increases and vice versa. The fuel feed duct and/or the oxidant feed duct further includeS a bypass circuit for increasing the supply of fuel and/or oxidant, where the bypass circuit includes a parallel pipe mounted in parallel to the first feed circuit, and a bypass valve that opens or closes the bypass circuit. The valve of the parallel pipe is arranged to open when the main valve of the ejection means is permanently open.