The present invention essentially relates to an electric machine (1.1) with homopolar double excitation, comprising a rotor particularly consisting of a central portion (51) made of a solid magnetic material and a laminated annular portion (53) located at the periphery of the solid portion. In addition, the rotor comprises permanent magnets (54), the magnetization thereof being radially oriented relative to the axis (33) of the rotor (31), and separated from one another such that the double excitation flow generated by the field coils (38, 39) can enter the rotor (31, 67) via the flanges (48, 49) of the rotor, and come back out via the spaces between the magnets (54), or vice-versa.