Brushless wound-rotor doubly-fed electric machine
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 | It has been suggested that this article be merged with Doubly-Fed_Electric_Machines, Wound-Rotor_Doubly-Fed_Electric_Machines and Brushless_Doubly-Fed_Electric_Machines. (Discuss) Proposed since June 2007. |
The brushless wound-rotor [synchronous] doubly-fed electric machine (i.e., electric motor or electric generator) is a proprietary technology that incorporates the most optimum electromagnetic core structure of any electric machine, which is the core structure of the wound-rotor doubly-fed electric machine, but without the Achilles' Heel of the wound-rotor doubly-fed electric machine, which is the multiphase slip ring assembly with control instability. Development of the brushless wound-rotor [synchronous] doubly-fed electric machine seems to be limited to one company, Best Electric Machines (http://www.bestelectricmachine.com).
As the only known wound-rotor doubly-fed technology that eliminates the multiphase slipring assembly and guarantees stability at any speed, the theoretical attributes of the wound-rotor doubly-fed electric machine are approachable:
- Up to 50% reduction in system cost;
- Up to 50% reduction in system electrical loss;
- Up to 50% reduction in system physical size.
How it works
The brushless wound-rotor [synchronous] doubly-fed electric machine (i.e., electric motor or electric generator) incorporates a proprietary multiphase electromagnetic commutator that instantaneously emulates the speed dependent electrical excitation requirements of the electric motor or electric generator under control, regardless of speed. Similar to an electromechanical commutator, which discretely changes current flow in a single phase winding according the speed and position of the shaft and with a degree of resolution determined by the number of mechanical switches occupying a limited physical volume, the electromagnetic commutator smoothly changes current flow to multiphase winding sets of the doubly-fed electric machine and with significantly higher degree of resolution than the electromechanical commutator. Simultaneously, the electromagnetic commutator exchanges virtually pure sinusoidal multiphase electrical power between the rotor (or stator) multiphase active winding set(s) and the electrical power grid without electrical-mechanical contact of any kind (i.e., brushless).
The brushless wound-rotor [synchronous] doubly-fed electric machine supports any electric machine form-factor, such as linear moving, rotational, axial flux, or radial flux form-factor.
Unique attributes of brushless wound-rotor doubly-fed technology
Only as convenience for operational illustration, the electromagnetic commutator can be considered akin to the electromechanical commutator but with substantially more resolution of servo-like control and without brushes or sliprings. Because the multiphase excitation waveforms are instantaneously produced precisely to any speed, there is no opportunity for instability that is common to all other means of control, such as Field Oriented Control, which iteratively performs complex time based transformations and waveform synthesize by remote electronic processing. Further, the electrical power grid and windings of the electric motor or generator under control are isolated from any high frequency components, which dramatically improves power quality while protecting winding insulation and bearings. The unique attributes of the brushless wound-rotor doubly-fed technology incrementally improve efficiency and reliability while lowering system cost.
Nothing approaches the brushless wound-rotor doubly-fed electric machine technology, if cost, efficiency, and power density, combined, are the deciding factors.