Toroidal Winding Research Articles

Novel method for construction of high performance nanocrystalline FeCuNbSiB toroidal core

In the current study magnetic, magneto-optical and microstructural properties of the amorphous Fe83Cu1Nb3Si5B8 alloy were properly investigated depending on the external treatments such as annealing and stress annealing. Kinetic nanocrystallization temperatures of certain ribbon were determined at the range of 500–510 °C. The amorphous ribbons produced in the as-spun state were subjected to tensile stress loading with and without rapid heat treatment of 510 °C during 5 s. Behaviors of certain ribbons were extensively investigated in terms of several factors such as magnetic properties, microstructural evaluation, magneto-optical effects and structural deformation by means of quasi-static hysteresis loops, XRD analyses, TEM micrographs, magneto-optical Kerr imaging and nanoindentation test. Present nanocrystalline Fe83Cu1Nb3Si5B8 alloy have allowed yielding not only ultrafine grain structure of around 7.02 nm but also saturation induction of 1.85 T, coercivity of 5.8 A.m−1 and saturation magnetostriction of 6 ppm. Additionally, based upon determined optimum stress annealing circumstances, toroidal nanocrystalline core was produced using a proposed stress induced winding (SIW) system. SIW system based principally on the gradient of the rotational speed of each mandrel in the standard toroidal core winding machine. Structural deformation of the core was determined by an analysis method performed on the ribbon. Accordingly, induced elastic modulus (E), Poisson's ratio (V) and residual strain (ε) in the ribbon under the influence of stress annealing by 200 MPa at 510 °C were found as 7.9 GPa, 0.39 and 0.031, respectively.

Complete subdomain model for radial-flux slotted PM machines with toroidal windings accounting for the iron-part

Most subdomain models do not solve the magnetic vector potential in the iron part of the machine, this paper proposes a complete subdomain model for (PM) machines with toroidal windings and mainly solves the magnetic vector potential in iron part. The proposed model can accurately predict the field distribution under load or no-load conditions. The electromagnetic parameters of the motor (including magnetic flux density, back-emf, electromagnetic torque, and cogging torque) are calculated using the proposed analytical model, and validated by a FEM model. This paper presents a technique to handle with the stator of machines with outer teeth and the very specific techniques to solve the magnetic field in the iron part.

Design and Multi-Mode Operation of Double-Stator Toroidal-Winding PM Vernier Machine for Wind-Photovoltaic Hybrid Generation System

This paper proposes the design and multi-mode operation of a new double-stator toroidal-winding permanent-magnet vernier (DSTW-PMV) machine, which is for the wind-photovoltaic (W-PV) hybrid generation system. In the W-PV system, the wind and PV power are complementary with each other for power variation reduction. Through the multi-mode operation, the output voltage of the machine can be stabilized with high continuity under different rotational speeds to solve the inherently indeterminate wind speed problem and further improve the power smoothness of the whole W-PV system. First, the machine optimization is carried out to obtain the optimal pole-pair combination and geometrical topology for the proposed machine. Second, based on the optimal topology, the multi-mode operation principle of the output voltage adjustment is illustrated. By utilizing the diversities of the toroidal winding configurations and terminal connection strategies, the proposed machine accommodates 54 operating modes with different output voltages under rated speed. Accordingly, under the rated output voltage, the machine speed can be extended to three rated speed with high continuity. Furthermore, some modes generate the rated output voltage with identical speed, which contributes to the high redundancy and high operating efficiency. Hence, with the multi-mode operation and the auxiliary of the PV power, the whole power generation system accommodates the higher flexibility, stability, reliability, and efficiency.

ОЦЕНКА ВОЗМОЖНОСТИ НАРАБОТКИ ДЕЛЯЩИХСЯ ИЗОТОПОВ ДЛЯ РЕАКТОРОВ ДЕЛЕНИЯ В БЛАНКЕТЕ ТЕРМОЯДЕРНОГО РЕАКТОРА

Calculations for the fusion reactor were carried. The purpose this one is assessment of an opportunity to use blanket of these units for fission isotopes reproduction for fission reactors. This paper contains: - full scale 3D model, where 1/8 space part was used (symmetry), biological shielding and toroidal coil winding were included in model, model size about 5,8 m for every X,Y,Z geometry axis; - results by MCU and LUCKY-A codes of neutron fluxes, reaction rates; - reproduction coefficient for thorium-232 as relation to intensity of neutron source; - analysis of results. MCU and LUCKY-A computer codes use parallel calculation technologies to get solution transport equation.

Analysis and Design of Ironless Toroidal Winding of Tubular Linear Voice Coil Motor for Minimum Copper Loss

Due to the ironless structure of the toroidal winding in the tubular linear voice coil motor (TLVCM), the winding thickness is one of the critical parameters that have an impact on air-gap flux density, and hence affects the copper loss at rated thrust. This paper investigates and determines the thickness of the ironless toroidal winding of the TLVCM for the purpose of a minimum copper loss. Magnetic equivalent circuit (MEC) method is used to analyze the air-gap flux density with respect to winding thickness, and the corresponding copper loss at the rated thrust is assessed by considering the slot fill factor. The optimal solution is obtained according to the U-shaped curve of the copper loss. Moreover, the finite-element analysis is combined to validate the results of MEC method, and a good agreement is reached. Two prototypes of TLVCMs having similar slot fill factor are made, one of which is with the optimal winding thickness. The expected current at the rated thrust is obtained by a test platform of static thrust, so as to obtain the corresponding copper loss for each prototype. The experimental results show that the TLVCM with optimal winding thickness features a lower copper loss. Hence, the attempt to minimize the copper loss by designing the thickness of the ironless winding is highly effective.

Design and analysis of a high-performance dual-rotor PM synchronous reluctance machine with toroidal windings

This paper presents a dual-rotor permanent magnet synchronous reluctance machine (PM-SynRM) with toroidal windings to improve the magnetic torque and the utilization of two torque components, thus to obtain high electromagnetic performance, such as torque, efficiency, and power factor. To highlight the advantages of the proposed dual-rotor PM-SynRM, all of its machine characteristics, including airgap flux density, back electromotive force (EMF), torque, power, efficiency, and flux weakening capability are compared to those of a conventional PM assisted SynRM (PMA-SynRM) with the same machine size and operating conditions, with the aid of a finite element method (FEM) using the JMAG-Designer. Furthermore, the proposed dual-rotor PM-SynRM is verified to have superior endurance against the magnet irreversible demagnetization within five times of the rated current excitation.

Core Loss Estimation in Electric Machines With Flux-Controlled Core Loss Tester

The complexity of core loss estimation is a serious challenge in the design of high-efficiency electric machines. Current estimation methods based on the Steinmetz equation and loss separation are not accurate enough, even at the rated conditions. This paper describes a loss estimation technique combining finite-element analysis (FEA) and actual core loss measurements. First, flux density waveforms in various parts of the electric machine are determined using FEA. Second, the same waveforms are generated in a wound toroidal core made of the same material as used in the machine. The loss is measured per unit mass, and then the total motor core loss is calculated by integrating the measured W/kg loss values for predefined sections of the motor. These estimation results are compared with those of the Bertotti method. The proposed procedure is shown to improve the accuracy of loss estimation.

A Novel Direct-Drive Permanent Magnet Synchronous Motor with Toroidal Windings

A direct-drive motor has the merits of low speed, high torque, and elimination of mechanical deceleration mechanisms, and is widely used in various fields. A novel direct-drive permanent magnet synchronous motor is presented herein, in which all coils are wrapped around the stator yoke in the same orientation. The structure of the novel direct-drive permanent magnet synchronous motor with toroidal windings (N-TWDDPMSM) is introduced and its operating principle is analyzed by describing the variation in the armature magnet field versus time. Furthermore, based on the same power grade and mechanical size, several finite-element models of motors with different windings are established using Magnet software to analyze the distribution of magnetic field, back-electromotive force (back-EMF), power-angle characteristics, loss characteristics, etc. Compared with the traditional permanent magnet synchronous motor (T-PMSM), the traditional permanent magnet synchronous motor with toroidal windings (T-TWPMSM), and the N-TWDDPMSM, the N-TWDDPMSM shows advantages of low speed and high torque, and the feasibility and superiority of the N-TWDDPMSM are verified.

Pulse Magnetization of Strap Toroidal Magnetic Core

Diffusion of the pulse magnetic field into the metal of the toroidal magnetic core wound by a transformer steel strap is considered. The 1-D numerical model has been developed, which takes into account the viscous-type dynamic losses of magnetization, as well as the eddy currents. The parameter of viscous-type dynamic losses of magnetization was measured on samples of cold-rolled anisotropic transformer steel. The processes of magnetic field propagation in the strap, when the transformer is switched to the voltage source, have been analyzed, and the iteration algorithm of calculation of magnetic field in the strap has been developed. The experimental data have confirmed the obtained calculation results. The problems of application of transformer steel in pulse transformers are considered.

Design Considerations of a Transverse Flux Machine for Direct-Drive Wind Turbine Applications

This paper presents the design considerations and analysis of a double-sided transverse flux machine (TFM) for direct-drive wind turbine applications. The proposed TFM has a modular structure with quasi U-core stators and toroidal ring windings. The rotor is designed with ferrite magnets in a flux-concentrating setup to achieve high air gap flux density. This paper presents the different aspects of the TFM, taking into consideration the critical geometric parameters affecting the back-EMF waveform, phase inductance, torque density, and power factor. Three-dimensional finite element analysis (3D-FEA) was used to analyze and optimize the critical TFM design parameters to meet the performance specification. A proof-of-concept prototype was developed based on the proposed design considerations. The prototype was experimentally tested at different operating points and the results showed good correlation with the 3D-FEA results.

Electromagnetic Design and Losses Analysis of a High-Speed Permanent Magnet Synchronous Motor with Toroidal Windings for Pulsed Alternator

The configuration of conventional high-speed Permanent Magnet Synchronous Motors (PMSMs) is usually long and thin, with overlong axial end winding lengths, which is not suitable for those applications that place severe restrictions on the axial length, such as pulsed alternators. This paper first studied the key design aspects of a flat-structure high-speed PMSM. The toroidal-windings, low-conductivity material of the retaining sleeve, large airgap and segmentation of magnets were studied to reduce the axial length of the motor. The division of the stator and the employment of a non-magnetic outer stator were used to improve overall performance. Then the losses of the prototype were calculated and the factors having an influence on the losses were also investigated, after which, their effects on the total loss were evaluated. The total loss could be effectively reduced by the decrease of strand number of conductors and the division of stator, while only being slightly reduced by epoxy resin pole fillers. Metal-stack pole fillers have the same effect on the reduction of rotor loss as epoxy resin, while maintaining the good thermal-conductivity of metal. In addition, the influence of the carrier frequency of the inverter on the losses was analyzed, and it was found that high carrier frequency was helpful to reduce rotor losses. Finally, a small-scale prototype was manufactured and the experimental results were provided.

High-Voltage Generator with Constant Magnets and Toroidal Winding for Intermitted Mode of Operation

The paper proposes the use of High-Speed Permanent Magnet Generators Short-Time together with a gas turbine to start a starter generator. This paper describes the design features of the High-Speed Permanent Magnet Generators Short-Time with galvanically unconnected windings of the Gram using the example of a 3-phase and 6-phase HSPMGST with two biased three-phase windings with a pulse power of up to 10 kW and an operating time of not more than 1 minute with the breaks between starts not more than 5 minutes. The losses in these electric generators have been estimated, their thermal calculations have been carried out and experimental studies have also been carried out.

A wave shaping approach of ferrite inductors exhibiting hysteresis using orthogonal field bias

Advances in power electronic systems have considerably contributed to a wide spectrum of applications. In most power electronic circuits, inductors play crucial functions. Utilization of ferrite cores becomes a must when large inductances are required. Nevertheless, this results in an additional complexity due to their hysteresis nature. Recently, an efficient approach for modeling vector hysteresis using tri-node Hopfield neural networks (HNNs) has been introduced. This paper presents a wave shaping approach using hollow cylindrical ferrite core inductors having axial and toroidal windings. The approach investigates the possibility of tuning the inductor permeability to minimize circuit harmonics. Details of the approach are given in the paper.

Electromechanical converters for electric vehicles

The paper presents the analysis of various constructive schemes of synchronous electromechanical converters with permanent magnets fixed on the rotor and asynchronous with the short-circuit rotor. Various electrical stator winding schemes have also been compared, demonstrating the efficiency of copper utilization in toroidal windings. The electromagnetic calculus of the axial machine has particularities compared to the cylindrical machine, in the paper is presented the method of correlating the geometry of the cylindrical and axial machines. In this case the method and recommendations used in the design of such machines may be used.

Structural, magnetic characterization (dependencies of coercivity and loss with the frequency) of magnetic cores based in Finemet

We report changes of coercivity, induced magnetic anisotropy, magneto-optical domain structure and frequency dependencies of coercivity and energy loss (up to 10MHz) associated with the structural modifications produced by thermal treatments under applied magnetic field (field annealing) in toroidal wound cores of Fe73.5Cu1Nb3Si15.5B7 amorphous alloy. The thermal treatment (535°C, 1h) leads to the typical nanocrystalline structure of α-Fe(Si) nanograins (60–65% relative volume, 10–20nm average grain size embedded in a residual amorphous matrix, while the magnetic field with the possibility to be applied in two directions to the toroidal core axis, that is in transverse (which is equivalent to the transverse direction of the ribbon) or longitudinal (equivalent to the longitudinal direction of the ribbon), develops a macroscopic uniaxial magnetic anisotropy in the transverse (around 245J/m3) or longitudinal (around 85J/m3) direction of the ribbon, respectively. It is remarkable the quasi-unhysteretic character of the cores with these two kinds of field annealing as comparing with that of the as-quenched one. Magneto-optical study by Kerr-effect of the ribbons provides useful information on the domain structure of the surface in agreement with the direction and intensity of the induced magnetic anisotropy. This induced uniaxial magnetic anisotropy plays a very important role on the Hc(f) and EL(f) curves, (f: frequency), being drastic the presence and direction of the induced magnetic anisotropy. In addition, these frequency dependencies show a significant change at the frequency around 100Hz.

Novel Variable-Field Machine With a Three-Dimensional Magnetic Circuit

We propose a novel variable-field machine with toroidal windings to achieve both miniaturization and high efficiency. The proposed machine is characterized by a structure that uses three-dimensional (3-D) magnetic flux to increase the number of torque-generation faces. The 3-D structure prevents an increase in the machine volume due to the addition of variable-field coils. We investigated the principle of variable-field function using finite-element analysis and experimentation. We verified that the induced voltage and torque can be changed by regulating the direct current in the variable-field coil. Moreover, the field current revealed the effect of the no-load loss.

Bilateral International Inductance Comparison Using Traveling Standards in Thermoregulated Enclosures

Standards with toroidal windings are traditionally used for international comparisons of inductance. The achieved uncertainties of the comparisons are dominated by the rather high temperature coefficient of the traveling standards. Hence, thermoregulated enclosures were developed at Physikalisch-Technische Bundesanstalt (PTB) a few years ago. These have now been refined and their suitability for the transportation of standards has been proven in a bilateral comparison between PTB and VTT Technical Research Centre of Finland Ltd. The agreement was excellent, while the overall uncertainty of the comparison varied from 14 to 62 $\mu \text{H}$ /H in the frequency range 100 Hz–2kHz.

Analysis of a Dual-Rotor, Toroidal-Winding, Axial-Flux Vernier Permanent Magnet Machine

In this paper, a vernier permanent magnet (VPM) machine with dual-rotor toroidal-winding axial-flux topology is analyzed. Through the combination of toroidal windings with the rotor-stator-rotor topology, the end winding length of the proposed machine is significantly reduced compared with that of the regular VPM machine. Based on the airgap permeance function, the back-EMF and torque expressions are derived and the nature of the machine is revealed. The influence of pole ratio (ratio of rotor pole pair number to stator pole pair number) and main geometric parameters, such as slot opening, magnet thickness, etc., on electromagnetic performance is then analytically investigated in detail. Both the quasi-three-dimensional (quasi-3D) finite element analysis (FEA) and 3-D FEA are applied to verify the derived equations. Finally, a prototype of the proposed machine has been manufactured and experimentally evaluated. The test results agree well with both theoretical and FEA analyses. With the current density of 5.8 A/mm 2 and slot fill factor of 0.35, the torque density of the proposed machine prototype can reach 31.9 kNm/m 3.

A new dual stator linear permanent-magnet vernier machine with reduced copper loss

In this paper, a new dual stator linear permanent-magnet (PM) vernier (LPMV) machine with toroidal winding is proposed and analyzed. The proposed machine enjoys the advantages of less copper usage and copper loss without sacrificing the thrust force performance. For a fair comparison, the proposed machine is designed with the same geometrical parameters based on the conventional dual stator LPMV machine with concentrated winding. Finally, the electromagnetic performances of the proposed machine and the conventional one are compared and analyzed by using finite element method, verifying that the proposed machine with the low copper loss can obtain high force density.

Rna Compaction in the Presence of Polyvalent Cations

The effects of polyvalent cations on the effective size and charge of double-stranded DNA (dsDNA) have been well studied. In the presence of polyvalent cations, dsDNA in dilute solution undergoes a single-molecule, first-order phase transition, otherwise called condensation: more explicitly, upon onset of 90% neutralization of the phosphate backbone, the DNA undergoes discontinuous compaction into tightly wound toroids. However, the effects of these cations on long single-stranded RNAs (ssRNA) have not been well characterized. In this study we use centrifugation methods to examine the effective size of long ssRNAs in solutions of increasing concentration of the tetravalent cation spermine. In contrast to the case of dsDNA, we find only a continuous decrease in the size of ssRNA upon increase in spermine concentration. However, the decrease is significant enough to suggest that RNA molecules longer than viral genomes can be packaged in vitro into virus-like vectors for gene delivery.