A synchronous electric machine includes a stator having a plurality of teeth with first and second active surfaces; first and second stator windings having respective series of first and second coils wound on said teeth; first and second rotors having respective series of first and second permanent magnets with alternate polarities and facing said respective first and second active surfaces; wherein the first coils and the second coils of each stator winding are arranged in pairs, with two coils of each pair offset from each other by a predetermined angle; and wherein, during operation as a motor, two first coils of each pair produce concordant torque contributions on the first rotor and discordant torque contributions on the second rotor and two second coils of each pair produce concordant torque contributions on the second rotor and discordant torque contributions on the first rotor.