Brushless Wound-rotor [Synchronous] Doubly-fed Electric Machine stabilized by real-time control

Choices for today's electric ship propulsion systems include the asynchronous (i.e., induction) singly-fed or doubly-fed electric machine systems or the synchronous singly-fed electric machine systems with permanent magnets or DC field-windings (e.g., superconductor). Experts theorized that the variable-speed Brushless Wound-rotor [Synchronous] Doubly-fed Electric Machine System (BWRSDF), which can symmetrically motor or generate, provides higher efficiency, higher power density, higher torque density, and lower cost than any other electric machine system but only with the discovery of a practical brushless real time control solution for its known issues of instability and the multiphase slip-ring assembly that continually elude state-of-art control methods, such as Field Oriented Control (FOC). Comprising a dual-ported transformer circuit topology with the robust characteristics common to the advanced induction electric machine system, such as field weakening, practically unconstrained torque and power rating, etc., the fully electromagnetic core of the BWRSDF uses readily available technology and materials without the cost, safety and reliability issues of market volatile, rare-earth permanent magnets. A patented with patents pending Brushless and Sensorless Real Time Control (BSRTC) method provides the only available BWRSDF.