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Brushless Real Time Control (BRTC):


Only the patented Synchro-Sym electric machine system (SS-EMS) with Brushless Real-Time Control (BRTC) eliminates the "passive" rotor components found in all other electric machines (EM), such as PMs, reluctance saliencies, squirrel cage windings, electromagnets, by simply replacing the passive component with a similar armature (i.e., "active" multiphase winding set) as the stator armature.  As a result, the rotor real-estate becomes an "active" participant in the energy conversion process as already provided by the stator real-estate (i.e., doubly-fed). By reasonably assuming the rotor real-estate displaces the same volume as the stator real estate, particularly in an axial-flux (or disk shape) footprint, and understanding two armatures are the most possible without EM circuit topology duplication, converting an EMS to an active rotor armature with the same power rating as the stator armature provides double the power rating in the same size package as the original EM (i.e., the sum of the rotor and stator armature power ratings). Since cost, loss, and power density are always normalized to the total power rating of the EMS, the SS-EMS provides nearly half the size, half the loss, and half the cost of any other EMS while still using the same performance optimizing techniques, which are available to all.


Until the recent invention of Brushless Real Time Control (BRTC) [1] for implementing synchronous operation of a wound-rotor doubly-fed EMS [2], electric machine experts have only theorized the attractive attributes of the wound-rotor doubly-fed [synchronous] EMS. Now the patented with patents pending SS-EMS is the only practical EMS with rotor real-estate actively (and synchronously) participating in the energy power conversion process for nearly twice the power within the same size package, half the loss, and half the cost of any other EMS, including the rare earth permanent magnet (RE-PM) electric machine system. Unlike the asymmetrical transformer (or single-ported) circuit topology of all other electric machine systems, which quickly show flux density saturation of the electrical steel core with increasing torque current, the symmetrical transformer (or dual-ported) circuit topology of only the SS-EMS neutralizes the increasing production of air-gap flux density (and core saturation) regardless of increasing current on each side of the air-gap.[3] As a result, the SS-EMS has factors higher peak torque production than the closest EMS competitor, which is particularly attractive for transmission-less propulsion applications, such as electric vehicles. For another level of cost, efficiency, and power density improvement, the constant baseline flux density of only the SS-EMS core can be designed closer to the flux saturation limit of the electrical steel core (or closer to peak flux density) for highest air-gap flux density without concern of core saturation when increasing torque current. As an integral component of the SS-EMS, BRTC is a direct AC-to-AC conversion method without the large reactive components (e.g., capacitors, chokes, etc.) of the conventional DC Link Stage Converter and as a result, BRTC is significantly more compact, more efficient, and less costly than the traditional DC Link Converter of Flux Vector Control.  As a fully electromagnetic electric machine (i.e., only AC windings on rotor and stator),  the SS-EMS can operate with sinusoidally distributed magnetic fields and as a result, can leverage a legacy of design and manufacturing practices without the tedious iterative optimization analysis when designing with discretely distributed DC field windings, permanent magnets, or reluctance saliency. Finally for another level of lower cost, higher efficiency, and smaller size, BRTC only controls half the power of the EM entity, which is a well known attribute of the doubly-fed EM.



NOTE: Why not just eliminate the extraneous rotor "passive" components altogether, such as expensive RE-PMs, air-gap area robbing reluctance saliencies, squirrel cage windings, or DC electromagnets, that only consume precious EM real-estate without actively participating in the energy conversion process (or work) and instead, simply replace the rotor passive components with another armature excited by BRTC that provides up to double the power density, one-half the cost, and one-half the loss in the same size package by brushlessly controlling half the power as only the Synchro-Sym EMS (i.e., SS-EMS) can do!


[1] In accordance with the SS-EMS Concept of Operation, Brushless Real Time Control (BRTC) automatically phase locks to a predefined steady-state condition with no additional need for offline measurements and compensatory responses with associated inaccuracies and time delays; hence, real time control.

[2] All electric machines experience induction due to harmonics or due to asynchronous speed between the rotor and stator movement (i.e., speed based induction). Therefore to distinguish between an Induction (i.e., asynchronous) EMS and a synchronous EMS, an Induction EMS "relies" on speed-based induction for functional operation and  a synchronous EMS "does not rely" on speed-based induction for functional operation, although a synchronous EMS may experience speed-based induction.

[3]The merits of the double armature, doubly excited, wound-rotor machine as a low reactance, high torque energy converter configuration are well known. . Its continuous power rating is double that normally associated with a given frame size; in addition, it has a maximum pull-out torque of approximately eight times nominal frame size torque rating. [page 526, column 1, paragraph 6, Norbert L. Schmitz and Willis F. Long, "The Cycloconverter driven Doubly-fed Induction Motor," IEEE Transactions on Power Apparatus And Systems, Vol. PAS-90, No. 2, March/April 1971, pp. 526-531.]

[Just The Facts For Comparisons]

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Note: The Radial Flux prototyping of the Advanced Brushless Wound-Rotor Synchronous Doubly-Fed Electric Motor Or Generator System is shown as our Icon, which predates the axial-flux SS-EMS Technology.


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