Patent ID: 8049458

Claim:
A synchronous rotary electric machine, comprising: a stator in which a plurality of phases of armature windings are wound; a rotor having a rotor core in which a field winding is wound and being placed to face the stator for rotation; a current limiting element connected in series to the field winding to limit, to one direction, a flow direction of induction AC (alternating current) current induced through the field winding in response to armature current passing through the armature windings so that the field winding is allowed to pass a field current therethrough along only the one direction; and a current control circuit that comprises means for supplying to the armature windings a fundamental component of the armature current which corresponds to a synchronizing current for producing a rotating magnetic field rotating in sync with the rotation of the rotor and adjusting a frequency of the synchronizing current to change a rotation speed of the rotor, means for supplying to the armature windings a pulsed rotor exciting current for causing the field winding to induce the field current therethrough only during a specified current-supply duration which is set to be shorter than one cycle of the synchronizing current, and means for setting the number of times of current supply for the pulsed rotor exciting current, per electrical angle of 2π of the rotor and per phase, so as to have a positive correlation with the cycle of the synchronizing current.