SYNCHRO-SYM Technologies



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NOTE: Generally located on the rotor, permanent magnets (PM) do not "actively" contribute to electromechanical power conversion and as a result, PMs are "passive" devices (e.g., PMs have no electrical power port to contribute active power to the electromechanical power conversion). In reality, the "active" multiphase winding set required by all electric machines (that is generally located on the stator for electrical connection convenience) determines the torque and power rating of any optimally designed electric machine, including PM electric machines, with the high energy product of the very expensive rare earth (RE) PM only determining the ease of setting up the air-gap flux density (without considering the addition of field weakening).  When optimally designed, the effective air-gap area and the following size of the active multiphase winding set (per unit power rating) are determined by the air-gap flux density, which is design constrained by the flux saturation limit of the magnetic core and core material, such as laminated electrical steel, instead of the high energy product of RE-PMs or the even higher peak magneto-motive-force (MMF) potential of a winding compensated for heat dissipation (after all it takes winding MMF to actually magnetize a PM). (Note: Superconductor electric machines are excluded from this discussion, although SYNCHRO-SYM Technologies can bring superconductor electric machines closer to practicality).  The high energy product of RE-PMs show smaller size and support a deeper air gap (for instance, 1 mm vs 2 mm) but electromagnetic windings provide field weakening for extended speed range. In consideration, the size of the stator assembly (with the active multiphase winding set) determines the size of the rotor body and together, the rotor and stator bodies with robust structural frames overwhelmingly determine the size of the electric machine.  It follows that all optimally designed electric machines show virtually similar "rated" torque, similar effective air-gap area, and similar size active winding set with similar air-gap flux density. As supporting evidence, today’s specialty induction electric machines (with copper rotor and optimized materials and designs) are achieving similar size and efficiency for a given rated torque as optimally designed RE-PM electric machines (but without the extravagant cost and manufacturing issues of RE-PMs).


NOTE: Unlike winding magnetizing MMF, passive, delicate, expensive, environmentally unfriendly, and cartel controlled permanent magnets, such as rare earth permanent magnets (RE-PMs), show degrading performance over normal operational life, such as demagnetization, which accelerates during peak torque stress, such as expected in an electric vehicle application. More daunting, the globally minable supply of RE-PM materials may not meet the expected global demand (even with difficult recycling), if RE-PM electric machines become the electric machine of choice. In consideration, comparable alternatives are being aggressively researched. Fully Electromagnetic (i.e., no permanent magnets), only SYNCHRO-SYM already provides a better alternative.


NOTE: Packaging, winding, and thermo management techniques consume significant size and cost of any electric machine because of the large dynamic and magnetic forces exerted on the frame and bearings and the thermo dissipation of the active multiphase winding set(s) found in all electric machines, including PM electric machines.


NOTE: Doubly fed electric machines uniquely show the performance and power of two active multiphase winding sets in the same package, which equates to twice the power density.


NOTE: Without considering the formidable issues of cryogenics, superconductor electric machines achieve tens of times more winding MMF (and resulting air gap flux density) than conventional copper windings or PM coercivity. Without providing details, SYNCHRO-SYM Technologies can bring superconductor electric machines closer to practical reality.


NOTE: Without actively contributing (or adding) to electromechanical conversion power, core material, which is found in all conventional electric machines, and permanent magnet material are “passive” materials, regardless of their performance improving qualities, such as directing the magnetic path to the air-gap by the high permeability of the core material. Note: Even the “coreless” or yokeless terms seem to suggest there is no core material but in fact, the magnetic path is routed through the PM core material, which exhibits the density of steel but the permeability of air, and the back-iron with the density and permeability of electrical steel.


NOTE: Traditional synchronous electric machines, such as permanent magnet electric machines, precisely know the magnetic flux phase angle regardless of rotor speed by the mechanical angle of the rotor position and do not rely on slip-induction for rotor magnetic field production. In contrast, asynchronous (or induction) electric machines rely on slip-induction for rotor magnetic field production and the magnetic flux phase angle varies relative to the mechanical position and time constant of the rotor. As a result, synchronous electric machines have precise control but asynchronous (induction) electric machines use estimation for control because the rotor time constant changes with at least heat. Consequently for both induction and traditional synchronous electric machines, delays in measurement and excitation synthesis by conventional state of art offline processing always contribute to stability issues, particularly at speeds or frequency with large time constants, such as at low speeds.   In contrast, SYNCHRO-SYM is a synchronous electric machine by the actions of BRTEC, which automatically phase locks the magnetic flux to a known and selectable phase position (without regard to speed), eliminates reliance on slip-induction for rotor magnetic field production, and does not have processing delays (real time) or shallow time constant signal measurement issues.


NOTE: Electric machines with a primary and secondary winding transformer circuit topology (asymmetric or symmetric), such as single and doubly fed induction and doubly-fed synchronous electric machines, show higher peak torque potential (e.g., 2-3 times rated torque) than electric machines that are truly asymmetric (e.g., no rotor or secondary multiphase winding set), such as electric machines with PMs or saliencies (reluctance) replacing the secondary winding set (e.g., 1.5 times rated torque). Universal electric machines, such as the electromechanically commutated DC electric machine, show peak torque up to 5 times rated torque. Only SYNCHRO-SYM has a truly symmetric (or dual ported) transformer circuit topology that in accordance with physics, airgap flux density stays constant with increasing active current (or torque current for electric machines).  As a result, only SYNCHRO-SYM shows factors of higher peak torque potential (e.g., 8 times rated torque). See electric machine torque 101 whitepaper for details.


The high peak torque density of SYNCHRO-SYM is essential for direct Drive (transmission-less) drive-trains for electric vehicles, which are simpler, more reliable, less costly, lower maintenance, and most likely smaller than an electric motor and transmission combination. For instance, Rimac is selling a complete motor/transmission package for electric vehicles because of limited peak torque density of their RE-PM electric machine. For utility vehicles (without performance suspension), SYNCHRO-SYM is the best electric machine alternative for in-wheel motor applications, such as presently provided by Protean and Elaphe.  





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