Synchronous machine having hybrid rotor excitation

A rotor for an electric machine, comprising:

• an outer surface, an opposite inner surface, and a rotor body defined between the outer surface and the inner surface;
• a plurality of permanent magnets embedded within the rotor body, wherein at least one of the plurality of permanent magnets produces a constant magnet field having a magnetic axis along a direct axis (D-axis);
• and
• a plurality of excitable electromagnets embedded within the rotor body, wherein at least one of the plurality of excitable electromagnets, when excited, produces a variable magnetic field having a magnetic axis offset from the D-axis.

A synchronous machine having a hybrid rotor excitation, comprising:

• a stator configured to generate a rotating magnetic field when energized, wherein the stator includes an interior surface defining a rotor cavity;
• a rotor having an outer surface, an opposite inner surface, and a rotor body defined between the outer surface and the inner surface;
• a plurality of permanent magnets embedded within the rotor body proximal to the outer surface, wherein at least one of the plurality of permanent magnets produces a constant magnet field having a magnetic axis along a direct axis (D-axis);
• and
• a plurality of excitable electromagnets embedded within the rotor body proximal to the inner surface, wherein at least one of the plurality of excitable electromagnets, when excited, produces a variable magnetic field along a magnetic axis offset from the D-axis.