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Step 1: Simply remove the non-optimal asymmetry of the “passive rotor assembly,” which comprises slip-induction dependent windings, reluctance saliencies, DC or single phase field windings, or rare-earth permanent magnets, and the full power rated derivative of flux oriented controller from the ubiquitous asymmetric electric motor circuit and control architecture. The passive rotor assembly reasonably consumes half of the real estate, loss, or cost of any asymmetric electric motor or generator circuit and control architecture but cannot contribute additional working power to the electromechanical energy conversion process. The other half of the electric motor real estate, loss, or cost is consumed by the universally essential “active stator assembly,” which comprises a directly excited bi-directional multiphase winding set that determines similar overall power rating (and size) between any asymmetric electric motor when optimally designed with the same air-gap flux density, material, winding, and packaging techniques.
Step 2: Then simply replace the passive rotor assembly with the optimal symmetry of an “active rotor assembly,” which comprises another similarly rated directly excited multiphase (or active) winding set that is found on the active stator, as only possible with the stabilization of a half power rated brushless real time emulation controller (BRTECTM). Unlike the passive rotor assembly, only the “active rotor assembly” of the symmetric electric motor circuit and control architecture, called SYNCHRO-SYM, contributes additional working power to the electromechanical energy conversion process along with the active stator assembly, while consuming the other half of the electric motor real estate, loss, or cost.
Result: In accordance with the governing Law of Conservation of Energy, the symmetric circuit and control architecture of SYNCHRO-SYM effectively: a) eliminates the entire loss, cost, and size of the “passive rotor assembly,” b) doubles the continuous power density of the original asymmetric electric motor or generator system (per unit of power rating), c) halves the cost (per unit of power rating), d) halves the loss (per unit of power rating), e) provides octuple the peak controllable torque (per unit of power rating), e) provides leading, lagging or unity power factor adjustment at any speed, including zero speed, and coveted field weakening capability, and f) eliminates exotic materials, such as rare earth permanent magnets.
All electric motor and generator systems (i.e., electric machine systems) follow the classic textbook study that begins with the symmetric electromagnetic relationships (see 4.1.19 – 4.1.23 of Figure 1) of the multiphase wound-rotor [synchronous] doubly-fed electric machine system, which comprises the symmetry of two “directly excited multiphase winding sets (i.e., active winding sets)” on the rotor and stator, respectively, but only by postulating a multiphase excitation means during its study that is brushless, instantaneous (i.e., real time), sensor-less & automatic (i.e., emulation), and bi-directional (i.e., brushless real time emulation excitation control or BRTEC TM) in order: a) to avoid the instability of relying on slip-induction excitation, particularly about synchronous speed where slip-induction ceases to exist, b) to provide continuously stable synchronous operation throughout its double constant-torque speed range (i.e., double Maximum Load RPM) for a given frequency of excitation (e.g., sub-synchronous to super-synchronous speeds, including synchronous speed), and c) to provide automatic and instantaneous compensation to random rotor shaft or line perturbations without the instability of offline electronic processing and delays. Note: The same symmetric electromagnetic relationships become the follow-on study for the asymmetric (or all other) electric machine system by deoptimizing their symmetry with the relational asymmetry of a passive rotor assembly of slip-induction dependent windings (i.e., asynchronous electric machine), rotor saliencies (i.e., asynchronous and synchronous electric machine ), or permanent magnets (PM) and DC field windings (i.e., synchronous electric machine ) under a derivative of Field Oriented Control.
With a simple qualitative method of: a) removing the field oriented controller (FOC) and the passive rotor disk assembly (and rotor bearing) of any axial-flux (i.e., adjacent and similar active stator disk and passive rotor disk) “asymmetric electric motor or generator system,” which does not contribute working power to the electromechanical energy conversion, and then b) replacing with another “active” stator disk assembly (with the addition of the rotor bearing), which contributes an additional increment of working power to the electromechanical energy conversion as only possible by the stabilization of brushless real time emulation control (BRTECTM), the original axial-flux “asymmetric” electric machine system packaging becomes the axial-flux “symmetric” electric machine system of the patented SYNCHRO-SYM. By the symmetric power magnification of two active winding sets on the rotor and stator, respectively, which doubles the power of the single active winding set on the stator of the original non-optimal asymmetric electric machine system by stably operating from sub-synchronous to super-synchronous speed, then in accordance with the governing Law of Conservation of Energy, SYNCHRO-SYM effectively: 1) doubles the contiguous constant-torque speed range (i.e., Maximum Rated Load RPM) for a given torque, pole-pair count, and frequency and voltage of excitation, which is tantamount to double the power density, half the cost, and half the loss of the original core (per unit of power rating), 2) eliminates the entire size, cost, and loss of the original asymmetric rotor of “passive” rare-earth permanent magnets, slip-induction dependent windings, reluctance saliencies, or DC field windings, 3) provides coveted field weakening with halve of the Magnetizing MMF loss by sharing Magnetizing MMF between the rotor and stator active winding sets on each side of the airgap, 4) provides octuple the controllable peak torque (and peak power density) by holding the air-gap flux density constant below the core flux saturation with increasing torque current in accordance with the conservation of energy physics of a dual ported transformer topology, and 5) provides leading and lagging power factor, including unity power factor, and 6) doubles the expected gain from strategically applying the same performance enhancing material, windings, packaging, thermal management, electronic component, and manufacturing techniques under the same air-gap flux density to the original asymmetric electric machine system at any speed, including zero speed.
For over a century, SYNCHRO-SYM‘s leap in performance was verified during the last century of classic electric machine study by postulating BRTEC. More recently, SYNCHRO-SYM has been verified: a) by lengthy analytical analysis, b) by several progressive stages of prototyping, by retrofitting off-the-shelf electric machines, including pre-production prototyping, and more importantly, c) by the evolution of a SYNCRO-SYM customized computer aided design tool (BEM-CAD) that simultaneously provides side-by-side RE-PM and Induction electric machine system comparisons, all of which are designed to the same electrical and mechanical parameters with the same air-gap flux density, winding, material, packaging, thermal management, and electronic component techniques for competitive fairness. So like all electric motor and generator systems, SYNCHRO-SYM is routine engineering and manufacturing ready for power scaling to any customer specification; all without considering the BEM-CAD interface to the only 3D Printer method of axial-flux electric machine systems with amorphous or nanocrystalline ribbon, called MOTORPRINTER.
ELECTRIC MOTOR & GENERATOR COMPARISON TRADE SPACE:
- Only a directly excited multiphase winding set (or active winding set) produces a rotating magnetic field that symmetrically contributes active (or working) power to the electromechanical energy conversion process in accordance with its power rating while consuming loss, cost, or size (together with its rotor or stator mounting assemblies). Generally, the active winding set is located on the stator to avoid the complexity of moving rotor electrical provisioning with stable excitation control. In contrast, a) slip-induction dependent windings, which are electrically powered through the extra sized stator active winding set, b) DC field windings, which are not multiphase AC winding sets, c) reluctance saliencies, which obviously have no electric port for active power connection, or d) permanent magnets, which obviously have no electrical port for active power connection, cannot contribute additional active power to the electromechanical energy conversion process but still consume loss, cost, or size (together with their mounting assemblies).
- All electric machines (i.e., electric motors, generators, and transformers) are optimally designed with similar air-gap flux density because air-gap flux density is determined by the permeability and saturation limit of the same electrical steel core available to all and not by the residual flux density potential of rare-earth permanent magnets (RE-PM) or the boundless flux density potential of an electromagnet. Because high air-gap flux density determines at least torque production, establishing the largest possible airgap flux density within the flux saturation limit of the same electrical steel core is the first steady state design criteria for any electric machine. Although RE-PMs are shallower than an electromagnet when producing an air-gap flux density under one Tesla at operating temperature and reasonable air-gap depth, the necessary active winding set on the stator still determines the effective air-gap area and associated torque (and overall size) of any electric machine.
- Commonly misunderstood, all optimized electric machines of comparable rating, including so-called yokeless or ironless electric machines, have similar amounts of core iron to at least provide the universally essential back-iron for optimally closing the magnetic path through the airgap, increasing air-gap flux density, and reducing the amount of expensive RE-PM material or Magnetizing MMF. However, yokeless or ironless electric machines admirably reduce rotor inertia but by sacrificing thermal management and structural integrity.
- Today, all electric machine circuit and control architectures (EM-CCA) incorporate electronic excitation control for optimum performance or practical operation and therefore, an equitable comparison between competing electric machines should always be a “system” comparison with at least including the designed Maximum Load RPM (or constant torque speed range) with the compounding loss, cost, and size of the electronic controller.
- In accordance to the classic textbook study, there are only two electric machine circuit and control architectures (EM-CCA) for comparative convenience: 1) the optimal symmetric EM-CCA with the symmetry of an “active” rotor assembly, which comprises another directly excited multiphase winding set (or active winding set) in addition to universally essential active winding set found on the “active” stator assembly as only practical with the patented brushless real time emulation control (BRTECTM), and 2) the non-optimal asymmetric EM-CCA with the asymmetry of a passive rotor assembly, which comprises slip-induction dependent windings, reluctance saliencies, pm, or DC field windings under field oriented excitation control (FOC).
- Commonly confused with the asynchronous (or slip-induction) doubly-fed electric machine system or asymmetric EM-CCA, a practical “synchronous” doubly-fed electric machine system or symmetric EM-CCA has never materialized, because of the formidable challenges of realizing the essential BRTEC for “continuously synchronous stability” from sub-synchronous to super synchronous speeds, including zero and synchronous speed, although early symmetric EM-CCA research began with the advent of practical high speed electronic and magnetic control (circa 1960’s) but never effectively realized.
- With over a century of legacy practice, electric machine design knowledge and manufacture are straight-forward, regardless of the EM-CCA. Coupled with the past elusiveness of BRTEC for implementing the most “optimum” EM-CCA, which is the symmetric EM-CCA, the unswaying inertia of huge public and private R+D investment in alternatives, such as in the RE-PM electric machine systems, and the common belief that everything that can be invented has been invented, electric machine research was conveniently redirected to the development and strategic application of readily available electric machine material, winding, packaging, high speed electronic control, and manufacturing techniques for enhancing the performance of the century old asymmetric EM-CCA, such as the permanent magnet (PM) EM-CCA after the advent of a high energy product rare-earth (RE) PM (circa 1980’s) that provided a practical means of eliminating the provisioning, cost, size, and loss of Magnetizing Magneto-Motive-Force (MFF). But ironically, the provisioning, loss, cost, and size of Magnetizing MMF is being re-instituted into the RE-PM EM-CCA to regain the coveted attribute of field weakening capability.
- With the optimal symmetry of equally rated active winding sets on the rotor and stator, respectively, the symmetric EM-CCA shows twice the loss and cost, which is neutralized by twice the power rating within the same package of materials as the single active stator of the asymmetric EM-CCA. As a result, the symmetric EM-CCA normalizes to the same loss, cost, size per unit of power rating as just the active stator of the asymmetric EM-CCA and with the entire loss, cost, and size of its “passive rotor” of slip-induction dependent windings, reluctance saliencies, permanent magnets, or DC field windings completely eliminated. Therefore at any speed, including zero speed, the symmetric EM-CCA shows up to half the loss, half the cost, and half the size as the asymmetric EM-CCA per unit of power rating by reasonably assuming the rotor of any EM-CCA consumes the same size, loss, and cost as the stator, particularly if the EM-CCA is an axial flux slip-induction asymmetric EM-CCA.
- With the magnifying working power contribution of two active winding sets on the rotor and stator, respectively, the symmetric EM-CCA doubles the performance gain expected from the same readily available electric machine material, winding, packaging, and electronic component techniques that were empirically applied to the asymmetric EM-CCA for performance distinction.
- Constrained by a circuit and control architecture with the loss, cost, and size of a “passive rotor assembly” of slip-induction dependent windings, DC field windings, reluctance saliencies, or permanent magnets that cannot contribute additional active power to the electromechanical energy conversion process, all asymmetric EM-CCAs show similar loss, size, and cost, if optimally designed with similarly available air-gap flux density, winding, material, electronic component, and packaging techniques. Therefore, extraordinary differences in performance claims between manufacturers of asymmetric EM-CCA must be unfairly comparing the different application of universally available optimizing techniques. In contrast with an “active rotor assembly” comprising a directly excited multiphase winding set that contributes additional active power to the electromechanical energy conversion process along with the active stator, the symmetric EM-CCA, which utilizes both the rotor and stator for working power production, achieves up to twice the performance of the asymmetric EM-CCA, which utilizes only the stator for working power production with similar available air-gap flux density, material, winding, electronic control, and packaging techniques.
- The symmetric EM-CCA inherently: a) has the coveted field weakening capability for extended speed range, b) is without cogging drag from permanent magnet persistent magnetism, or c) is without the extravagant cost, environmental harm, unsustainable global supply chain, and geopolitical consequences of “rare-earth permanent magnets” that make permanent magnet electric machines expensively practical.
- The symmetric EM-CCA provides optimal performance at any speed with tuned excitation control of both the rotor and stator active winding sets.
- The symmetric EM-CCA brings superconductor electric machine systems closer to practical reality by contactless relocation of the superconductor field windings to the stator assembly while eliminating harmonic heating experienced with the power conditioning of FOC; but when AC superconductors become a practical reality, the fully electromagnetic SYNCHRO-SYM, which is without delicate and limited lifetime permanent magnets, will become the electric machine system of choice.
- In accordance with the classic study of electric motors, generators, and transformers, the symmetric electric machine system of SYNCHRO-SYM is the pinnacle of electric motor or generator circuit and control architecture but only with the stabilization of a brushless real time emulation control means.
SIMPLE QUALITATIVE PROOF:
In accordance to Lorentz Force Law, all electric machines produce force with two orthogonal flux (or current) vectors, which are the Torque Flux produced by the torque magneto-motive-force (MMF) and the Magnetizing Flux produced by a) Magnetizing MMF, b) the product of rare-earth permanent magnet (RE-PM) coercivity and its depth, or c) the magnetic path reluctance change. Only RE-PMs produce Magnetizing Flux without magnetizing electrical power and as a result, the RE-PM asymmetric electric machine is without Magnetizing Flux electrical loss, which has driven its application. In contrast, the reluctance, slip induction, and dc field wound asymmetric electric machines show similar Magnetizing Flux electrical loss but only the Symmetric Electric Machine, which operates with half of the Magnetizing MMF on the rotor and stator, respectively, shows half the electrical loss associated with Magnetizing MMF. The slip-induction asymmetric electric machine has the additional burden of experiencing the dissipation from both the rotor and stator slip-induction excitation power (or loss) and as a result, the stator must be additionally power rated (and sized) for the power of the rotor. All electric machines have a degree of core loss, including RE-PM electric machines, and as a result, all are constructed with lamination of low reluctance but high resistivity material to reduce hysteresis and eddy current losses.
The total loss (i.e., electrical and core), cost, and size of an “asymmetric electric machine system” is the sum of the loss, cost, and size associated with the active stator and the passive rotor assemblies but the total power rating is determined by the single stator active winding set (i.e., singly fed). Without including the associated loss, cost, and size of the characteristic, fully rated electronic controller of singly-fed electric machine system, which shows significant compounding impact to the total system loss, size, and cost, and by normalizing the loss, cost, and size of the rotor or stator assemblies to a unit of 1 (per KW of power rating), the asymmetric electric machine system would reasonably show 2 normalized units of loss, cost and size per KW of power rating (i.e., 2 normalized units of loss, cost, and size for the active stator and for the passive rotor divided by 1 unit of power rating). Similarly, the impossible but best case assumption for the asymmetric electric machine system, such as the RE-PM electric machine system without assuming rotor core loss, would show 1 normalized unit of loss but with 2 normalized units of cost and size per KW of power rating (i.e., 2 normalized units of cost and size for the stator and rotor but with 1 normalized unit of loss for the stator and with the unrealistic zero loss for the rotor divided by 1 unit of power rating).
By conveniently replacing the passive rotor and bearing assembly of slip-induction dependent windings, rotor saliencies, DC field windings, or RE-PMs of the asymmetric electric machine system with a rotor core and bearing assembly comprising another active winding set as found on its universally essential active stator assembly, all of which are under the same air-gap flux density, the same air-gap effective area, the same voltage and frequency of excitation, and the same speed and torque design, the resulting “symmetric circuit and control architecture” of SYNCHRO-SYM (as only possible with BRTEC) comprises an “active winding set” on both the stator and rotor assemblies, respectively, providing double the total power rating (i.e., doubly-fed) as the single “active stator assembly” of the asymmetric electric machine system. Without including the associated loss, cost, and size of the known characteristic of “half rated” electronic power conditioning for doubly-fed electric machine control, which would show significantly lower compounding impact of the characteristic “full rated” controller of the single fed asymmetric electric machine system, the symmetric electric machine system would reasonably show 1 normalized unit of loss, cost, and size per KW of power rating (i.e., 2 units of loss, cost, and size for both the rotor and stator active winding sets divided by 2 units of power rating), which is half the loss, cost and size of the reasonable case assumptions without considering the superior loss, cost, and size performance of BRTEC over FOC.
By a simple qualitative method of proof and without introducing the significant compounded loss, cost, and size associated with the electronic controller (system), it was easily demonstrated that SYNCHRO-SYM will always be at least smaller, as efficient, and less costly than any asymmetric electric machine system, such as the rare-earth permanent magnet (RE-PM) electric machine system, for a given power rating by as much as half as large, half as costly, and half as lossy. By introducing the significant compounded loss, cost, and size associated with the electronic controller (system), SYNCHRO-SYM will always show significant performance over any asymmetric electric machine system, including the RE-PM electric machine system.
OTHER RETROFIT COMPARISONS:
The same SYNCHRO-SYM retrofit comparison can be applied to any asymmetric electric machine circuit and control architecture that always comprises a “passive asymmetric rotor assembly” of rare earth permanent magnets (RE-PM), slip-induction dependent windings, reluctance saliencies, or DC field windings:
- The Magni250 and the EMRAX348 are by far, the most optimized asymmetric electric machine circuit and control architectures. Both use rare-earth permanent magnets and are axial flux form, which is a stator disk adjacent to a rotor disk configuration, with the strategic application of material, winding, electronic component, and packaging techniques. The comparative BEM-CAD design results show SYNCHRO-SYM provides twice the power density at half the cost and half the loss of the Magni240 and the EMRAX348, while providing up to 8x more peak torque.
- The “Synchronous Reluctance” electric machine system is sometimes described as a simple performance improving retrofit to the common slip-induction electric machine system by keeping the “active” power producing stator assembly but by replacing the “passive” slip-induction dependent squirrel cage rotor assembly with a reluctance (SyncR) rotor assembly that may include embedded rare-earth permanent magnets and a sophisticated waveform shaping field oriented controller (FOC) derivative for smoothing out the traditional issues of torque ripple and cogging of synchronous reluctance electric machine systems. Similarly to the slip-induction electric machine system retrofit, the complex passive rotor assembly and sophisticated FOC of any synchronous reluctance electric machine system can be replaced with an active rotor assembly and BRTEC to provide the symmetric circuit and control architecture of SYNCRO-SYM, which will double again the overall performance of the synchronous reluctance electric machine system while eliminating the extravagant cost, safety and handling issues of rare-earth permanent magnets.
Note: Tesla’s IPM-SyncR electric machine system shows the complicated SyncR rotor assembly of rare earth permanent magnets and reluctance saliencies placement but without emphasizing the complexities and ramifications of the essential electronic shaping controller to provide a practical IMP-SyncR motor with up to 96% efficiency or without emphasizing similar performance trade space of an optimized slip-induction motor with a less complex copper wound rotor assembly and electronic controller. Also overlooked, the essential electronic controller has compounding effects on the overall loss, cost and size of any electric machine “system.” For instance, if the efficiency of the motor is 96% and if the efficiency of the essential electronic controller is also an impressive 96%, the actual compounded efficiency of the Tesla’s IMP-SyncR motor “system” for practical operation is only 92% (i.e., 96% x 96%).
- LinearLabs’ Hunstable Energy Turbine (HET) rare-earth permanent-magnet (RE-PM) electric machine system (RE-PM-EMS) recently advertised a four rotor concept providing twice the torque density and triple the power density as other RE-PM-EMS, but after reviewing the video, the four rotor concept is actually a single rotor assembly (of the century old asymmetric circuit and control architecture) with four rotor segments completely surrounding the directly excited stator multiphase (or active) winding set (i.e., so-called circumferential flux of HET) and as admirably claimed, the winding end-turns are seemingly reduced with the effective air-gap area doubled. Without critiquing the practicality of a completely air-gap surrounded (or floating) active stator assembly without the necessary means to directly excite the stator multiphase (active) winding set, which would disrupt the crucial circumferential flux of HET, a SYNCHRO-SYM retrofit (as done with MAGNAX) would double the performance claims of LinearLabs’ HET motor while eliminating the cost, safety and handling issues of RE-PMs.
- By retrofitting the Nidec motor with the patented symmetric circuit and control architecture of SYNCHRO-SYM while using the same materials, winding, packaging, manufacturing, and thermal management techniques, Nidec’s electric motor performance would again be doubled and its production cost halved, all without including the additional savings of eliminating expensive rare earth permanent magnets or without transforming Nidec’s manufacturing with MOTORPRINTER, which is the only high speed 3D Printer of amorphous or nanocrystalline axial-flux electric motors and generators.
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