Results Of Electromagnetic Analysis Research Articles

Investigation of the effect of difference in the characteristic resistance of DP coils on the field and losses of MI HTS magnets

We found a significant difference between the central and end magnetic field delays during the testing of a metal-insulation (MI) high-temperature superconducting (HTS) magnet. In this paper, we first analyzed the reasons for the difference in the field, and the results show that it is mainly due to the difference in the characteristic resistance of each double pancake (DP) coil. We further evaluated the effect of the difference on the electromagnetic analysis results of the MI HTS magnet. Subsequently, we developed an equivalent circuit model that considers the difference in the characteristic resistance of the DP coils and used the model to analyze the effect of this difference on the fields and losses generated by the MI HTS magnets, especially for AC conditions. Finally, based on our analytical results, a coil arrangement strategy considering the characteristic resistance of each DP coil was proposed. This work can guide us in evaluating the magnetic field more accurately in future engineering applications and provide a coil arrangement strategy for the MI HTS magnet, which requires to excite rapidly or generate an alternating magnetic field.

Improved design and analysis for electromagnetic performance of magnetic geared permanent magnet machine according to winding pattern and segmentation of permanent magnet

This paper presents an analysis of the operating principle of magnetic geared permanent magnet machines (MGPMMs), electromagnetic analysis results according to the winding pattern, and a method for improving power factor and loss characteristics. To improve electromagnetic performance, the air gap magnetic flux density was calculated using the finite element method, and the harmonics of the inner and outer air gap magnetic flux densities was analyzed using the fast Fourier transform (FFT). From the FFT results, harmonic orders that affect electromagnetic performance were presented, and the electromagnetic analysis results were compared to derive correlations with torque ripple and losses. In addition, a design method for improving electromagnetic performance and operating characteristics was proposed by comparing power factors according to winding pattern. In particular, to improve the robust design and efficiency of MGPMM, a method of reducing eddy current loss by segmenting permanent magnets was addressed. The proposed analysis and design method can be widely used in the design and characteristic analysis of MGPMM.

Experimental results of electromagnetic analysis on smartcard

Abstract— Electromagnetic analysis attack is a form of side channel attack that can be used to reveal secret information of a cryptographic device by examination of electromagnetic radiations. The effectiveness of EMA has a large dependences on the quality of the electromagnetic radiation measured by the measuring system and how the EM traces are simulated during the key recovery procedures. In this paper, we propose the practical procedure for electromagnetic analysis attack methods and the experimental results of EMA on smartcard that implemented AES algorithm, including assessing the influence of measuring system, radiation leakage model on effectiveness of attacks.

A dual coil induction heating machine for jewelry factories developed by electromagnetic analysis

An induction heating machine (IHM) generates magnetic flux density (B) and high temperature for combining precious metals as products in a jewelry factory. Since factories require new generation IHMs for increased productivity and cost savings, a dual coil IHM development approach is presented here to replace conventional, single-coil IHM using electromagnetic analysis (EMA). First, the experiments and the EMA investigated B generated by a conventional one using the factory operating condition. Both agreed, confirming the methodology and reliability of the EMA, which was analyzed to determine Bp. The Bp represents a B property for the new dual coil IHM to be expected to generate a comparable signal to the single coil. Then, in development, two novel designs of dual coil IHM (series and parallel) were investigated based on current flow circuits. For these designs, Bp was investigated using the EMA. As expected, the EMA results showed that both coils generated a different Bp, which was unfortunately incompatible with the conventional IHM and thus was inappropriate in actual use. However, the series dual coil showed better applicability since it generated B higher than the parallel coil under the same operating conditions. Next, the EMA was applied to determine the Bp of the series dual coil by varying the applied current (I), frequency (f), number of coil turns (N), and distance between coils (d). Finally, the EMA results revealed two options of the series dual coil with the optimum I, f, N, and d generating Bp comparable to the conventional IHM, as intended, achieving the factory's need with two times the productivity.

Investigation on Effect of Shape of HTS Pole Coil on Airgap Magnetic Field of HTS Synchronous Motor

The High Temperature Superconducting (HTS) synchronous motors offer considerably higher torque and power densities along with higher efficiencies for strategic and critical industrial applications. The most widely explored airgap based topology for HTS synchronous motors has conventional copper windings in stator and HTS pole coils in the rotor. The shape of these rotor pole coils affects various electrical parameters of the motor. In this paper, a detailed investigation has been carried out on effect of shape of HTS pole coil on airgap magnetic field and rated open circuit characteristic (OCC) of an 8 MW HTS synchronous motor along with its other parameters like pole coil excitation current, peak magnetic field inside the motor, maximum perpendicular magnetic field on HTS tape and operating temperature of HTS pole coils through FEM based electromagnetic analysis. Based on the results of electromagnetic analysis, the optimum shape of HTS pole coil has been finalised.

Electromagnetic properties of crayfish and its responses of temperature and moisture under microwave field.

To reveal the application potential of microwave heating in the thermal processing of crayfish, this work explored the electromagnetic properties of different parts of crayfish and the patterns of temperature and moisture responses in crayfish during microwave heating. The results of electromagnetic analysis demonstrated that the electromagnetic properties of different parts of crayfish were different, and the tail had higher dielectric properties and reflective loss than other parts, but the maximum thickness of each part of crayfish was almost within their heating depth of microwave. The visual imaging and numerical simulation of temperature and moisture responses showed there were nonuniform temperature and moisture distributions in crayfish during microwave heating. The crayfish tail was selectively heated and rapidly cooked, but its moisture loss was far less than the mass loss of whole crayfish. Furthermore, the immobilized water in crayfish tail meat was continuously converted to free water, while the bound water was relatively stable during microwave heating. This work provided the theoretical references for the assumption that cooking the crayfish by microwave to overcome the shortcomings of boiling. PRACTICAL APPLICATION: In this work, we innovatively applied microwave heating to the heat processing of crayfish, and analyzed the electromagnetic properties of different parts in crayfish and explored its temperature and moisture responses under microwave field. Although this is a basic research, which provided some theoretical references for the assumption that microwave heating of crayfish (Procambarus clarkia) may be a clean and efficient means of overcoming the shortcomings associated with boiling. In particular, the simulation model of crayfish was established according to its real size and shape, which provided an option for the prediction of temperature response of crayfish in the microwave field.

Lightning Surge Analysis of HV Transmission Line: Bias AC-Voltage Effect on Multiphase Back-Flashover

This paper discusses the back-flashover (BFO) phenomena in a high-voltage (HV) vertical double-circuit transmission line by means of numerical simulations. The single- and multiphase BFOs are analyzed considering 24 cases of AC-voltage angles and nonlinear characteristic of flashovers, taking advantage of the circuit analysis method in time domain. The models used in circuit analysis are the TEM-delay model, which can take into account the non-TEM characteristics of tower and line, and the conventional models. Prior to the BFO analysis, the characteristics of circuit models are compared and discussed with the numerical electromagnetic analysis results. In BFO analysis, it is clarified that the occurrence probability of the multiphase BFO is heavily depending on the bias AC-voltages. The relation of measured BFO phases and AC-voltages are well explained by the TEM-delay model with the valid lightning current magnitude. The conventional circuit models could have underestimated the occurrence of BFOs in HV transmission lines. The analysis and discussions shown in this paper can be utilized for advanced evaluation of lightning performance of transmission lines that considers the seriousness of lightning accidents.

Influence of Laminating Materials and Modified Pole Shapes on the Performance of Segmented Rotor Switched Reluctance Motor

This work deals with the torque ripple minimization techniques of Segmented Rotor Switched Reluctance Motor (SSRM) for cooling fan application. Torque ripple, acoustic noise and vibration are factors resisting the segmented rotor SRM. To overcome this, stator and rotor pole modifications along with the effects of laminating steel material have been analyzed for the performance improvement of the machine. The performance of the machine with different laminating steel materials such as M19, M850-65A, M890-50d and M43 are compared with the conventional CR-10 steel material. With respect to pole shape modifications the analysis has been performed by considering stator pole taper, stator pole arc, rotor segement structure and rotor pole depth. The results highlight the influence of structural modifications and material properties on the performance of the motor. The results of electromagnetic analysis disclose that the segmented rotor configuration with M890-50d material exhibits superior electromagnetic characteristics.

Electromagnetic analysis of fully superconducting motor for electric aircraft

In order to reduce carbon emissions, there is considerable interest in all-electric aircraft for transportation. Fully superconductor motors will be required to meet the high specific weight requirements, which are >10 kW/kg for the NASA N3-X plane. This paper summarizes the results of electromagnetic analysis generated using the FEMM magnetics code, along with the Lua scripting language, to determine the optimum motor configuration for a 4 MW, 3000 rpm fan motor. In considering ac loss, the analysis assumes Bi-2212 stator windings and both iron-tooth and air-core designs are considered. The best selected case consists of an 8-pole configuration utilizing an armature current density of 100 A/mm2.

Design and analysis of interior permanent magnet machines equipped with novel semi‐overlapping windings

A novel winding topology comprising semi-overlapped windings has been proposed in this study. The main advantages of such winding over conventional-distributed (overlapping) and fractional-concentrated (non-overlapping) windings are having very short-end winding lengths and significantly low magnetomotive force harmonic content, respectively. The key design rules, basic properties, and other merits and demerits of the proposed novel winding topology are justified. The key performance characteristics of the proposed winding topology are disclosed through an interior-permanent magnet (IPM) machine. The obtained electromagnetic analysis results are compared with those of other IPM machines having conventional-distributed and fractional-concentrated windings. It has been demonstrated that the proposed winding topology promises significant superiorities such as improved efficiency with substantially reduced total axial length, low eddy current losses, and low risk of irreversible magnet demagnetisation over other winding topologies. The analysis is verified by finite-element analysis results and experiments on a prototype novel semi-overlapping winding IPM machine.

Design and Feasibility Study of a Performance Evaluation System for a Large-Scale HTS Generator Under Short-Circuit Conditions

Generally, in a high temperature superconducting (HTS) generator, a large magnetic air gap exists because of needed space for a cryostat or non-magnetic cores in the HTS generators. Consequently, the inductance becomes lower than conventional generators. As a result, the short circuit current becomes as high as more than 10 times the rated current. The design of the mechanical structure of a generator is very challenging to endure a high force and torque at the HTS field coils. Therefore, a performance evaluation system (PES) is required to test the HTS field coil and support structures of the generator. In this paper, the design and feasibility study of a PES for and HTS field coil of large-scale HTS generator are presented. The 10 MW class HTS generator and PES was designed based on the electromagnetic analysis results obtained using the finite element method. The torque and force of the HTS field coil were analyzed. As a result, the HTS field coil can be practically tested using the proposed PES whether the structure of the coil can withstand the high torque and force of the generator. The proposed PES design and short-circuit analysis results can be effectively used for the development of large-scale HTS wind power generation systems.

Design of an HTS module coil for a 750 kW-class superconducting wind power generator

Recently, high temperature superconducting (HTS) generators are being studied with the advantages of high efficiency, light weight and small volume compared with the conventional generators. However, the HTS generator requires a large vacuum vessel and has problems such as difficulties in maintenance of the HTS coil. These problems can be overcome through the modularization of the HTS field coil. This paper designs an HTS module coil for a 750 kW-class superconducting wind power generator. The HTS module coil was designed based on the electromagnetic analysis results obtained using a 3D finite element method. For detail structure of the module coil, the heat load analysis and the mechanical stress analysis were performed. As a result, the total heat load was minimized the temperature of the HTS coil could be kept below 30 K. The von Mises stress of the supports was less than the allowable stress of the glass-fiber reinforced plastic material. The design results of the HTS module coil can be effectively utilized to develop large scale the superconducting wind power generators.

Design and Comparative Analysis of Performance Evaluation Systems for a Large-Scale HTS Generator

Generally, in a high temperature superconducting (HTS) generator, the electromagnetic force can cause problems due to high current density and magnetic field. HTS field coils must therefore be structurally designed and analyzed to ensure the stability of the generator before the HTS generator is built. As part of the stability assessment, this paper designs a performance evaluation system (PES) for large-scale HTS generators and discusses comparative analysis with a generator model. The PES for a 10 MW class HTS generator was designed based on the electromagnetic analysis results obtained using the finite-element method. The detailed structures of the swing and fixed-type PESs were investigated taking into account the HTS coil, support, and stator components. The torque and force of the HTS field coil were analyzed and the results were compared with the generator model considering the amplitude and direction of the force of the HTS field coil to confirm the effectiveness of the PESs. As a result, the output torque and tangential force of the PESs were the same as those of the HTS generator. Although both types of PES can evaluate the torque and force of an HTS generator, the fixed-type PES is more suitable for the characteristic test of HTS field coil of large-scale HTS generators.

Design and Electromagnetic Analysis of an Induction-Type Coilgun System With a Pulse Power Module

This paper discusses the design and electromagnetic analysis of an induction-type coilgun system with a pulse power module. The voltage, current, force, velocity, acceleration, and efficiency of the coilgun system were analyzed using the finite-element method (FEM). A simplified FEM model was developed for ensuring both accuracy and rapid calculation times. Based on the results of the electromagnetic analysis, the geometry of the coilgun system was defined with the Taguchi method. The coil-type armature was applied for increasing the mutual inductance and projectile force. The electromagnetic analysis results were also compared with the analytical analysis results. The designed coilgun system was found to exhibit high energy efficiency and safety of the system. The design specifications and analysis results concerning the coilgun can, hence, be effectively utilized to develop a large-scale multistage induction-type coilgun system.

Electrical Characteristics of Wireless Power Transfer System with Repeating Coil for AGV Considering the Misalignment of Coils

This paper compares the electrical characteristics of S-P (Series - Parallel) type with those of a repeating coil type wireless power transfer (WPT) system. The features of the two types of WPT systems are described for same output power using a same coil model. In general, the misalignment of power transmitting and receiving coils causes an output power to decrease using resonance capacitors with large operations current and voltage. From the viewpoint, a compensation method for the misalignment is investigated to reduce this burden of the resonance capacitor. Simulation is made on electrical characteristics such as output power and power transfer efficiency of a proposed WPT system applied to automatic guided vehicle (AGV) based on an equipment circuit combining results of electromagnetic analysis. As a results, it is found that a repeating coil keeping the center position between the primary and secondary coils can suppress the burden of the resonance capacitor so as to improve the transmission power of WPT system.

Direct chill casting with reversing rotational electromagnetic field

In order to achieve higher qualities of aluminum metal products, fine grain structures of materials are required. It is well known that agitation of a liquid metal during solidification process is effective to promote grain size refinement. In this research, the reversing RMF, i.e., the RMF that reverses rotation direction of an electromagnetic field at regular intervals, was applied to a molten metal pool in a cylindrical container of a round billet of DC casting. Electromagnetic fields generated by the reversing RMF stirrer were measured and compared with simulation results of electromagnetic analysis. The molten metal in the pool caused a clockwise and a counter-clockwise flow by applying the reversing RMF, and the flow field was simulated by a CFD calculation. It was found that the liquid metal was effectively stirred with the reversing RMF, resulting a higher turbulent intensity of the liquid metal. Grain sizes of a billet were measured and a relation between the flows and the sizes were investigated.

The effect of simplifications of a numerical mesh on the results of electromagnetic analysis of the Nuclotron-type cable

The model of a single Nuclotron-type cable is presented. The goal of this model is to assess the behaviour of the cable under different loads. Two meshes with different simplifications are applied. In the first case, the superconductor in the cable is modelled as single region. Second mesh considers individual strands of the cable. The significant differences between the distributions of the electric current density obtained with both models are observed. The magnetic field remains roughly similar.

Design of a 150T pulsed magnetic field generator device

A 150T pulsed magnetic field generator device which can generate a 150T pulsed magnetic field by a single-turn coil with a 3mm diameter was designed to study the coupling of laser-produced plasma and strong magnetic fields is described. An 880 kA current pulse is discharged into the coil by a pulsed-power system composed of 20 capacitors of 5μF, electric-trigger switches, and low-impedance strip transmission lines. The structure of the generator was optimized based on the results of electromagnetic analysis. A set of small pulsed discharge system with a 50kV/5μF capacitor bank was built to research synchronous trigger and the current curve. The circuit verification experiment was proceeded and the result was revealed to be consistent with theoretical analysis.

Performance Test of a Metal Insulated HTS Magnet with Conduction Cooling

In the fabrication and operation of an HTS magnet, ensuring thermal stability against uneven quench is the most important factor. A sample HTS magnet was designed and fabricated with the metal insulation (MI) method and its fundamental characteristic analysis was conducted under the liquid nitrogen cooling system. On the basis of the electromagnetic analysis results, the thermal and mechanical structural design and detailed experimental analysis of the MI HTS magnet under the conduction cooling condition were performed in this paper. The conduction cooling condition was achieved using the 1st stage GM cryo-cooler. The characteristic resistances and the charging and discharging times of the magnet were measured according to the operating temperature of 32 K of the HTS magnet. The long-term current flowing test was conducted by monitoring the coil temperatures. In addition, the thermal stability of the HTS magnet was analyzed when the over current flowed into the magnet. The test results will be applied to the large size HTS MI magnet.

Structural Design of a Module Coil for a 12-MW Class HTS Generator for Wind Turbine

Recently, high-temperature superconducting (HTS) generators are being studied to reduce the weight and size of large-scale gearless generators. However, the large-scale HTS generators have problems relating to high electromagnetic force because of their high current density and magnetic field. Therefore, the forces acting on HTS field coils should be considered as well as their support structures. This paper discusses the structural design of a module coil for a 12-MW class HTS generator for wind turbine. The 12-MW HTS generator module was designed based on electromagnetic analysis results obtained using the 3-D finite-element method. The detailed structure of the module coil was investigated considering the HTS coil bobbin, support, and cooling system. For secure design of the module coil, stress and deformation analyses were performed. Structural analysis results were compared with safety factors and critical yield stresses for each material. As the results, electromagnetic force and maximum stress of the module coil were calculated, and pole-type supports were found to be the most suitable for the 12-MW class HTS generator.