Abstract: An electric machine such as an alternator for a motor vehicle is provided. The machine includes a stator and a rotor, the stator having at least one secondary winding received in at least one pair of slots. The rotor has at least two successive excitation magnets which generate two magnetic fluxes in the rotor and has components in opposite tangential directions around the structure of the rotor. The rotor has an even number of slots between the two magnets. The slots define projecting poles between them and receive winding legs that are suitable for being powered to co-operate with the magnets to define alternating poles. Each of the slots that receives the winding legs is occupied only by a single leg or by a plurality of legs wound around the same projecting pole. The shaft of the rotor is made of a magnetic material.