Wirelessly transferring power within an electric machine having AC and DC rotor coils

A method of operating for a field wound synchronous electric machine, the method comprising:

• carrying, by an auxiliary coil of a first rotor winding of a plurality of rotor windings of a rotor of the field wound synchronous electric machine, a first current induced by an AC current flowing in a stator of the field wound synchronous electric machine, the stator including stator windings configured to be energized to define stator poles and the rotor windings configured to be energized to define fixed rotor poles with associated teeth comprising a ferromagnetic material and including a winding portion and a cap;
• receiving, by a rectifier, the first current induced in the auxiliary coil, the rectifier being rotationally fixed to the rotor and electrically coupled to the auxiliary coil and to a primary coil of the first rotor winding;
• generating, by the rectifier, a second current from the first current induced in the auxiliary coil;
• and
• carrying, by the primary coil, the second current from the rectifier, the second current defining a fixed rotor pole of the fixed rotor poles that interacts with the stator poles to produce relative forces between the rotor and the stator,
• wherein a D-axis of the primary coil of the first rotor winding in a synchronous reference frame extends radially outward from a rotor shaft through the rotor pole of the rotor winding, and
• wherein a D-axis of the auxiliary coil of the first rotor winding in the synchronous reference frame is
• (i) substantially perpendicular to the D-axis of the primary coil of the first rotor winding in the synchronous reference frame, and the auxiliary coil extends through a first channel of the cap of a first tooth of the teeth and a second channel of a trunk of the rotor or the first tooth, or
• (ii) substantially aligns with the D-axis of the primary coil of the first rotor winding in the synchronous reference frame, and the primary coil and the auxiliary coil of the first rotor winding are wrapped around a winding portion of the first tooth of the teeth.