Rotating electrical machine

A rotating electrical machine of a brushless wound field type disposed between a stationary case and a rotating member that rotates inside the stationary case, the rotating electrical machine comprising:

• a stator held by the stationary case, the stator including an AC coil that generates a rotating magnetic field with an alternating current;
• a field core held by the stationary case, the field core including a field coil that generates a magnetic flux with a direct current;
• a rotor disposed such that an inner circumferential surface of the rotor directly contacts an outer circumferential surface of the rotating member to form a contact surface therebetween, the rotor held rotatably relative to the stator and the field coil;
• and
• a rotor side core portion including the outer circumferential surface of the rotating member, wherein
• a first air gap is formed between the stator and the rotor, and is configured to allow a magnetic flux to flow between the stator and the rotor,
• a second air gap is formed between the field core and the rotor, and is configured to allow a magnetic flux to flow between the field core and the rotor, and
• a third air gap is defined by the field core and the outer circumferential surface of the rotating member, and is configured to allow a magnetic flux to flow between the field core and the rotor side core portion, the third gap at least partly overlapping the contact surface between the inner circumferential surface of the rotor and the outer circumferential surface of the rotating member as viewed along an axial direction of a rotating axis.