SYNCHRO-SYM is a patented electric motor or generator system with a novel brushless integrated electric machine circuit and control architecture that

  1. significantly magnifies the peak torque potential and operational performance while reducing cost of the electric motor or generator system beyond the alternative century old electric machine circuit and control architectures used by all others;
  2. significantly magnifies the extra performance enabled by optimized electromagnetic materials, winding, or packaging techniques that all other electric machine systems are constrained to use for invention or performance improvement.

NOTE: SYNCHRO-SYM makes irrelevant any costly advancement in rare-earth permanent magnet materials or  electric machine systems, which have been considered to be the Holy Grail of electric machine system technology, such as provided by the ARPA-E REACT program.

To learn more visit our article “A Low-Cost Alternative to Rare-Earth Permanent-Magnet Electric Motors” published on

Because the active multiphase winding set (e.g., of the stator) is optimally designed to the same flux density saturation constraints of the core material equally available to all electric machines, regardless of the coercivity potential of RE-PM or the even higher flux intensity potential of winding MMF (see Important Design Consideration Note), the active multiphase winding set (e.g., of the stator) solely determines similar torque density, continuous power rating, and size between electric machines. But only the patented “electric machine circuit and control architecture” of SYNCHRO-SYM contactlessly (i.e., brushlessly) replaces the passive (and extraneous) rotor components, such as RE-PMs, slip-induction windings, field windings, and reluctance saliency, with an additional “active winding set” to double the power rating within the same footprint and with the same materials (for at least twice the power density at half the cost and half the electrical loss per unit of power). Furthermore with today’s state-of-art but century old electric circuit and control architectures, electric machine invention or improvement  is limited to advancements in material, packaging, winding, or manufacturing techniques equally available to all; but only the patented electric machine circuit and control architecture of SYNCHRO-SYM will again double the performance attributes of these advancements.


SYNCHRO-SYM is a patented, brushless, fully integrated electric machine circuit and control architecture comprising a brushless “multiphase” wound-rotor doubly-fed electric machine circuit topology and a brushless, low cost, multiphase, bi-directional, sensor-less, instantaneous, and automatic controller, called brushless multiphase real time emulation controller (BRTEC), that uniquely guarantees contactless, contiguous and symmetrically stable, “synchronous” doubly-fed operation (which requires precise control of airgap flux, speed, torque, and torque angle) during motoring or generating from any sub-synchronous to super-synchronous speeds, particularly at absolute or about synchronous speed where slip-induction ceases to exist or becomes unstable.

NOTE: Multiphase Real Time Emulation Control was theoretically known by electric machine experts since at least the 1960s to be essential for realizing a true “multiphase” wound-rotor “synchronous” doubly-fed electric machine systemwhich electric machine experts consider to be the ideal electric machine system, but real time emulation enabling technologies were not available until the invention of BRTEC.

Unlike the century old componentized circuit and control architecture used by all other electric machine systems, including state of art permanent magnet electric machine systems, the simple operating physics of the patented integrated electric machine circuit and control architecture of SYNCHRO-SYM (as only provided by BRTEC) eliminates reliance on the extraneous loss, cost, size, and complexity of “passive and extraneous” (or asymmetric electric machine) rotor assembly components, such as permanent magnets, reluctance saliencies, direct current (DC) field windings, and slip-induction windings, by brushlessly retrofitting (within the same electric machine physical footprint and materials) another “active” multiphase winding set on the rotor assembly (in addition to the customary active multiphase winding set on the stator assembly) for the only practical symmetrical electric machine system available.

NOTE: As a conceptual demonstration of SYNCHRO-SYM, envision the axial flux electric machine footprint with adjacent rotor and stator disks of similar size separated by a single air-gap. By reasonably assuming the electrical loss (e.g., efficiency) was predominantly determined by the “active” stator disk and the size and cost of materials (e.g., the bearings, frame, and amount of electrical steel, copper, or RE-PM) are similar between the “passive” rotor and the “active” stator disks, which intuitively depicts the RE-PM electric machine system, then removing the loss, size, and cost of the “passive” rotor disk by replacing with another “active” stator disk is tantamount to doubling the power rating and electrical loss (i.e., two “active” disks) within the same package size, appearance, and materials as the original electric machine.  Since loss, size, and cost of any electric machine are in ratio with the total power rating of the electric machine, the retrofit clearly demonstrates a conversion to twice the power density and half the cost per kilowatt but within the same package, the same material, the same construction, the same winding techniques, the same manufacturing techniques and effectively the same efficiency per kilowatt (without considering the small orthogonal magnitude loss associated with magnetizing MMF offset by the even lower compounded system loss associated with the necessary addition of doubly fed electronic control).

NOTE: By removing the “passive” (and therefore extraneous) rotor components that effectively waste precious real estate, such as rare-earth permanent magnets (RE-PM), and by brushlessly replacing the extraneous rotor components with an “active” rotor winding set that contributes to “real” power production (in addition to the stator “active” winding set) without changing the electric machine footprint or materials, only SYNCHRO-SYM doubles the power density and performance at half the cost. As a result, any future development of RE-PM cost-performance improvements for electric machines (even by ongoing Holy Grail R+D) becomes irrelevant because permanent magnets, like reluctance saliencies, squirrel cage induction windings, and DC field windings,  are just extraneous, “passive” components that effectively waste precious electric machine real estate (only to ascertain air-gap flux); but could otherwise be brushlessly replaced with another winding set in the same footprint (as only provided by SYNCHRO-SYM) that “actively” contributes to power production like the essential stator active winding set.

NOTE: The BRTEC sensorless and automatic speed synchronized frequency and phase control provides a linear and deterministic dual ported (symmetric) doubly-fed electric machine system for superposition and scalability:

  • Harmonics and magnetizing current (reactance) seen at one port is negatively seen at the other port or automatically cancelled by the electromagnetics of the position dependent flux high frequency transformer (PDF-HFT), unless artificially provided by BRTEC control software or mechanical positioning.
  • Although the shallow slopes of low frequencies (or low speeds) are very difficult to measure or synthesized (in a timely fashion) by today’s state-of-art controllers, BRTEC sensorlessly and automatically provides any (or low) speed synchronized excitation and as a result, pole count or excitation frequency become trade space for low frequencies or speed.

IMPORTANT: As the only practical brushless and symmetrically stable multiphase wound-rotor “synchronous” doubly-fed electric machine system, SYNCHRO-SYM has ample in-house study and prototyping (e.g., synchronous doubly fed) as well as legacy third-party study and manufacture (e.g., multiphase slip-ring wound rotor induction doubly fed). In consideration, SYNCHRO-SYM is routine engineering and manufacturing ready (e.g., simplest construction) for power scaling to any customer specification.

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