Variable frequency independent speed motor

A system comprising:

• a motor control unit including an inverter configured to generate an excitation signal having a high frequency modulation signal component and a secondary multiphase power component;
• and
• a motor comprising:
• a rotor;
• a stator;
• a high frequency transformer stage for transmitting the excitation signal from the stator to the rotor, the high frequency transformer stage having a first set of transformer windings positioned on the stator and a second set of transformer windings positioned on the rotor;
• and
• a main motor stage having a set of stator armature windings positioned on the stator and a set of main field windings positioned on the rotor, wherein the set of stator armature windings is configured to receive a main multiphase power signal from an alternating current power bus having a current that causes a first rotating magnetic flux that rotates relative to the stator, wherein an inductance between the second set of transformer windings and the set of main field windings filters the high frequency modulation signal component to form a secondary multiphase power signal, and wherein the set of main field windings is configured to receive the secondary multiphase power signal, the secondary multiphase power signal having a current that causes a second rotating magnetic flux that rotates relative to the rotor, wherein a combination of the first rotating magnetic flux and the second rotating magnetic flux causes the rotor to turn at a predetermined reference frequency.

A method comprising:

• receiving a main multiphase power signal at a set of stator armature windings coupled to a stator of a motor apparatus, the main multiphase power signal having a current that causes a first rotating magnetic flux that rotates relative to the stator;
• transferring an excitation signal from the stator to a rotor using a high frequency transformer stage that includes a first set of transformer windings coupled to the stator and a second set of transformer windings coupled to the rotor, wherein the excitation signal includes a high frequency modulation signal component and a secondary multiphase power component;
• receiving a secondary multiphase power signal at a set of main field windings coupled to the rotor of the motor apparatus and coupled directly to the second set of transformer windings, wherein an inductance between the second set of transformer windings and the set of main field windings filters the high frequency modulation signal component to form the secondary multiphase power signal, the secondary multiphase power signal having a current that causes a second rotating magnetic flux that rotates relative to the rotor;
• generating an electric phase signal based on the main multiphase power signal;
• receiving a rotor phase signal from an encoder configured to monitor rotation of the rotor;
• generating a combination phase signal based on a difference between the electric phase signal and the rotor phase signal;
• and
• generating pulse-width modulation signals based on the combination phase signal to control an inverter to cause the secondary multiphase power signal to have a frequency, magnitude, and phase that enables the first rotating magnetic flux and the second rotating magnetic flux to combine to turn the rotor at a predetermined reference frequency.