Field winding type rotating electric machine

A field winding type rotating electric machine comprising:

• a stator having stator windings of three or more phases wound therein;
• a rotor including a rotor core with a field winding wound thereon, the rotor being rotatably arranged to face the stator;
• a rectifying element connected in series with the field winding to restrict field current flowing in the field winding to one direction, the field current being generated by exciting the field winding with magnetic fields that are created by supplying stator currents to flow in the stator windings;
• a driver including a plurality of switching elements and configured to output electric power of a plurality of phases to the stator windings;
• and
• a controller configured to output, to the driver, control signals of the plurality of phases for performing any of a sine-wave energization, rectangular-wave energization and overmodulation energization according to rotational speed of the rotor,
• wherein
• a power factor of the field winding type rotating electric machine is cos θ, and
• the controller is configured to generate, when performing the rectangular-wave energization or the overmodulation energization, a voltage pulse pair, which induces a current pulse pair, by:
• setting a reference time to a center of an ON duration or an OFF duration of the control signal of a first phase of the plurality of phases;
• and
• providing a temporary ON duration and a temporary OFF duration after a predetermined angle from the reference time, the predetermined angle being within a predetermined range including cos−1 θ in electrical angle, the temporary ON duration being provided to temporarily turn ON the control signal of a second phase of the plurality of phases, which is different from the first phase, during an OFF duration of the control signal of the second phase, the temporary OFF duration being provided to temporarily turn OFF the control signal of a third phase of the plurality of phases, which is different from both the first and second phases, during an ON duration of the control signal of the third phase.