NOVELTY - The device (10) has compressors (12, 18) provided for compressing air to be supplied to a fuel cell i.e. polymer electrolyte membrane fuel cell. The compressors for compressing the air are serially connected to each other. A recirculation device (70) is arranged downstream to one of the compressors and upstream to the other compressor at an inlet point (74) and recirculates exhaust gas of the fuel cell. A rotor (24) is supported by a magnetic bearing in an axial direction. The compressors are driven using an electric motor (36) of a loading machine (75).    USE - Charging device for a fuel cell i.e. polymer electrolyte membrane fuel cell, of a fuel cell device (claimed) of a motor vehicle, and in a loading machine i.e. exhaust gas turbocharger.    ADVANTAGE - The recirculation device is arranged downstream to the compressor and upstream to the other compressor at the inlet point, and recirculates exhaust gas of the fuel cell, thus ensuring uniform gas distribution and reducing open circuit voltage by decreasing oxygen partial pressure, and hence reducing potential differences in the device and enabling standardization of oxygen partial pressure over the fuel cell and enabling humidification of cathode gas and a membrane of the fuel cell while operating a fuel cell device in an efficient and cost effective manner. The utilization of the compressors enables reduction of number of components of the charging device, thus reducing weight, installation space and cost of the charging device. The recirculation device recirculates exhaust gas of the fuel cell at reduced energy expenditure. The rotor is supported by the magnetic bearing in the axial direction, thus reducing frictional losses in the device due to absorption of forces.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for operating a fuel cell device of a motor vehicle.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic longitudinal sectional view of a charging device for a fuel cell of a motor vehicle.    Charging device (10)    Compressors (12, 18)    Rotor (24)    Electric motor (36)    Recirculation device (70)    Inlet point (74)    Loading machine (75)