Calculation Of Magnetic Field Research Articles

Analytical calculation of magnetic field of bearingless flux‐switching permanent‐magnet machine based on doubly‐salient relative permeance method

A doubly-salient relative permeance method is presented herein to predict the magnetic field of bearingless flux-switching permanent-magnet machines (BFSPMMs). Firstly, the subdomain model method is used to compute the magnetic field of slotless BFSPMMs. Then, the slotting effect of the stator and rotor is obtained by the doubly-salient relative permeance method. By combining the two above, the air-gap magnetic field of slotted BFSPMMs can be obtained. The doubly-salient relative permeance method is based on the theory of the subdomain model method. The whole doubly-salient structure is divided into several subdomains, and the Laplace equations for subdomains are established. Then, according to the boundary conditions between subdomains and the core, and the continuity conditions between adjacent subdomains, the equations are solved to calculate the slotting effect. Based on the proposed analytical model, the flux density and electromagnetic performances including back-electromotive force (EMF), torque, and suspension force are predicted and compared with the finite element method results. Furthermore, the back-EMF of the prototype motor is measured and the suspension experiments are carried out based on the analytical method. The comparison results and experiment results verify the validity of the analytical method.

Alternative Approach for the Calculation of Magnetic Field due to Magnet for Magnetic Field Visualization and Evaluation

The magnetic field of different geometry of the permanent magnet is analytically calculated by using basic principles of the magnetism in very easier approach. Concept of origin shifting and geometrical shape transformation are used to formulate the formula for cuboidal, cubical and cylindrical permanent magnets. This concept can be used for the analysis of magnetic field distribution in space around for permanent magnet as well as electromagnet in a very easier approach. Handy and simplified software is made to calculate the magnetic field due to permanent magnet and electromagnet at any desired position on space. Magnetic field visualization is also done in both magnitude and direction by using MATLAB. 

Rapid 3-D Magnetic Integral Field Computation of Current-Carrying Finite Arc Segments With Rectangular Cross Section

The computation of 3-D magnetic fields is a demanding task in the analysis of electrical machines and other electromagnetic devices. In this context, integral field calculation provides a smooth solution, high precision and resolution, “on-demand”-calculation, and an origin-based formulation of the magnetic field and the magnetic vector potential. However, conventional elliptic methods lead to huge parallelizable computing efforts and significant errors. In this article, a 3-D generic current-carrying arc segment with rectangular cross section is studied. A new analytic formulation is proposed to speed up the computation of magnetic fields and reduce the error by more than three orders of magnitude. In addition, the proposed magnetic vector potential expression has a similar accuracy as numerical integration. In fact, a significant reduction of the error level has been showcased clearly with respect to the existing approaches. This article is promising for improving the design methodology and optimization of large superconducting dipole magnets or arched end-winding geometries of large electrical machines.

Improved Evaluation of Magnetic Loss Inside Silicon Steel Laminations Under 3-D Multi-Harmonic Magnetizations

An improved method is presented to study the efficient numerical modeling of stray-field loss in magnetic shielding excited by a 3-D harmonic magnetic field. The experimental platform is established to obtain the magnetic properties and loss model of the silicon steel lamination under harmonic magnetizations. Experimental determination is improved for more accurate stray-field loss based on the engineering-oriented model TEAM Problem 21c-M1. Prediction and evaluation of stray-field loss and additional iron loss due to harmonic excitations are achieved by special treatment of material properties in the numerical calculation of the harmonic magnetic field.

Research on the Influence of Vibrations on the Dynamic Characteristics of AC Contactors Based on Energy Analysis

Aimed at the influence of the vibration environment on the performance degradation of AC contactors, the purpose of this study is to investigate the failure mechanism of AC contactors under vibration conditions. During the closing process of AC contactors, the impact energy of the iron core may change due to the vibration stress, which may have an uncertain effect on the parameters of the dynamic response characteristics of the contact, and affect the working performance and service life of AC contactors. In this paper, a double-E AC contactor is selected as the research object. Based on the calculation of the transient magnetic field of the electromagnetic mechanism, an energy distribution model of the AC contactor is established. Based on this, considering the influence of vibrations and the input electrical energy under different closing phase angles, the energy model of the iron core collision under simple harmonic oscillation is investigated. The steady-state vibration energy at different frequencies and accelerations is calculated, and its influence on the dynamic response parameters of the AC contactor is analyzed. Finally, the simulation model is verified by experimental data. The results show that the energy analysis model can effectively reflect and explain the uncertainty of the dynamic characteristics of AC contactors under vibrations, from the perspective of the mechanism.

ANALISIS ANOMALI SINYAL ULTRA LOW FREQUENCY BERDASARKAN DATA PENGUKURAN GEOMAGNETIK SEBAGAI INDIKATOR PREKURSOR GEMPABUMI WILAYAH LAMPUNG TAHUN 2016

Regional research had been done to analysis anomalies signal of ultra low frequency based on measurement data as an indicator of the geomagnetic earthquake precursor of lampung in 2016. To achieve purpose of the study conducted by the following steps: (i) Calculation of the total magnetic field of data; (ii) Daily Trend Analysis; (iii) the Fourier transform of the data Geomagnetic Anomaly; (iv) Localization Frequency ULF; (v) Calculation of Ratio Vertical-Horizontal (Polarization Ratio Z / H); (vi) Correction magnetic storms or Disturbance Strom Time (DST); (vii) the identification of earthquake precursors; (viii) Determination of OnsetTime, leadtime,and the direction of precursors. The results of the analysis of ten earthquakes with a magnitude above 5 MW have precursors between 11 to 30 days before an earthquake. Nine out of ten earthquakes studied had an earthquake precursors and precursors that do not have, this is because the distance is too far from the station Magdas in Liwa, West Lampung. Thus it can be seen that the precursor using the magnetic data can be used to make short-term predictions.

Pitch Effect of Helical Coils of Electromagnetic Forming

At present, solenoid (helical) coils are widely used in various researches, especially electromagnetic forming (EMF), due to their advantages of simple manufacture and high magnetic field strength. However, in the study of EMF, there are still some defects in the high precision calculation of solenoid coils in the magnetic field the main reason is that the solenoid coil is of non-axisymmetric structure, which is generally equivalent to the 2-D or 3-D axisymmetric structure in practical research. Not only can it ignore the effect of the pitch effect of the solenoid coil, but also causes a certain deviation in the calculation of the magnetic field. Hence, this paper establishes 5 helical coils and 3-D axisymmetric finite element coils models with different layers for comparative analysis. The simulation results show that the magnetic flux density distribution deviation of helical coil and the 3-D axisymmetric coil is small and can be ignored when the coil layers are 1 or 2 layers. However, the number of linear circles increasing, the deviation between the two increases obviously. Therefore, in the study of EMF, the effect of solenoid coil pitch effect on magnetic field calculation can be ignored when the layers, radius and pitch of helical coils are used less whereas the effect of solenoid coil pitch effect on magnetic field calculation must be considered when the layers, radius and pitch of helical coils are used more.

Magnetic Field Calculation of a Novel Electromagnetic Clutch Based on an Interpolating Element-Free Galerkin Method

In this paper, the interpolating element-free Galerkin method (IEFGM) is introduced to calculate the magnetic field distribution of a novel permanent magnet bistable electromagnetic clutch (BPMEC), which is used in the in-wheel motor drive system to flexibly connecting the wheel and motor to release the mechanical shock and electromagnetic impulsion. Firstly, the fundamental of the IEFGM is introduced, and a new weight function for magnetic field calculation is proposed. Then the nodes distribution is discussed, and the magnetic field distribution of the clutch is analyzed. Simulation results show the IEFGM can impose the boundary conditions directly and fewer nodes are employed, make the calculation efficiency higher. Finally, some experiments are carried out, the experimental results verified the effectiveness of the IEFGM in magnetic field calculation. The study results provide references for the application of the interpolating element-free Galerkin method in the magnetic field calculation.

Measurement of magnetic field of capacitor-coil target using proton radiography

Proton radiography is a widely used method to diagnose the electromagnetic field of plasma. When protons pass through the electromagnetic field of plasma, they are deflected by Lorentz force and redistributed on the recorder. How to reconstruct electromagnetic field from the experimental result is an open problem. In this paper, we take the laser-driven capacitor-coil target for example to introduce and compare particle tracing and flux analysis, which are two widely used methods in proton radiography experiment to reconstruct the magnetic field. The capacitor-coil target is an important method to generate strong magnetic field in laser plasma experiment, where the strong current flows in the coil and its producing magnetic field may be larger than kilotesla. Firstly, the theoretical magnetic fields of capacitor-coil target are calculated with current being 10 kA and 50 kA. Secondly, the Geant4 is used to simulate the proton radiographs, where protons with 7.5 MeV pass through the target and the theoretical magnetic field is recorded. Thirdly, the theoretical proton radiographs are analyzed by the flux analysis method, and two magnetic fields are reconstructed. Finally, the theoretical magnetic fields are compared with the reconstructed ones, and the advantages and disadvantages of these two methods are analyzed. Particle tracing rebuilds the geometry distribution of proton source, plasma magnetic field and recorder in experiment, and it needs few assumptions. However, it strongly relies on accurate calculation of theoretical magnetic field and proton trajectory, and it requires to change the magnetic field over and over to achieve a closest result to the experimental proton radiograph. Meanwhile, particle tracing method consumes a lot of computation sources. The flux analysis directly reconstructs the magnetic field from experimental proton radiograph. However, it is only applicable to the case of weak magnetic field, and the error becomes larger for the case of stronger magnetic field. A dimensionless parameter <i>μ</i> is used to estimate the deflection of proton in the magnetic field, which measures the amount of deflection per unit length in the interaction region. The flux analysis method is applicable to the <inline-formula><tex-math id="M601">\begin{document}$\mu\ll 1$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20200215_M601.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20200215_M601.png"/></alternatives></inline-formula> regime. Additionally, the target may absorb the proton when the energy of proton is low and produces shadow on the proton radiograph, which leads to some difference between the original magnetic field and the reconstructed result.

Analysis of Devices to Detect Longitudinal Tear on Conveyor Belts

Currently mining enterprises more and more often use belt conveyors for mining operations. The length of transporting rock mass could be several kilometers, so in most cases conveyor are used. The transported rock mass is rather heterogeneous, as a rule, it has inclusions in a form of large pieces with sharp edges and, in some cases, metal objects, which might cause longitudinal tears of various lengths on conveyor belts. They lead to significant repair costs or replacement of expensive conveyor belt, loss of transported material, and downtime of the major enterprise equipment. In the world practice various devices and systems to detect longitudinal tears on conveyor belts have been developed for their successful operation. In this paper, there is analysis of existing devices to detect longitudinal tears on conveyor belts based on the use of mechanical (detection of the transported cargo on the lower the conveyor section and measuring the belt width), ultrasonic and electro-magnetic energy, evaluation of changes in the magnetic field configuration, computer vision, infrared laser and x-ray radiation, image recognition software and embedded transponder chips.

A novel analytical calculation of magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping

This paper presented a novel analytical method for calculating magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping. Firstly, flux density without slots and complex relative air-gap permeance of slotted air gap are derived from conformal transformation separately. Secondly, they are combined in order to obtain normalized flux density taking account into the slots effect. The finite element (FE) results confirmed the validity of the analytical method for predicting magnetic field and back electromotive force (BEMF) in the slotted air gap of spoke-type permanent-magnet machines. In comparison with FE result, the analytical solution yields higher peak value of cogging torque.

Analytical calculation and analysis of air gap magnetic field for electromechanical integrated toroidal drive

This article introduces the operating principle and structural characteristics of the electromechanical integrated toroidal drive system. For its inner and outer toroidal double-stator structure, the equivalent current method is applied to calculate its spatial magnetic field, which is produced by the sector cylindrical magnetic teeth and the helical variable cross-section magnetic beam. For the application of the equivalent current method in the modeling of the magnetic field, an effective correction method is proposed. The flux density calculation models for the main magnetic field in the inner and outer air gaps are established under the unified coordinate system, and the analytical expression of magnetic field distribution in spatial air gap is deduced. Finally, the feasibility of the mathematical analytical model is verified by comparing the analytical calculation results with the finite element simulation results. The influences of the main structural parameters on the distribution of the air gap magnetic field and the torque are analyzed, which lay a theoretical foundation for the optimal design of the electromechanical integrated toroidal drive system.

The three-dimensional finite element forward modelling of complex excitation source NMR

Abstract Traditional nuclear magnetic resonance (NMR) is mainly applied to horizontal ground and one-dimensional electrical structures. However, calculations of the excitation fields rarely consider the three-dimensional electrical changes of the subsurface medium and undulating terrain, or the deformations caused by emission sources. Therefore, to analyse the influences of terrain fluctuations, emission source deformations and three-dimensional electrical changes on NMR, three-dimensional finite element forward modelling of undulating terrain NMR was conducted in this study. First, based on a scalar finite element method, the direct calculations of the excited magnetic fields of a three-dimensional electrical medium were realised, which improved calculation accuracy by avoiding the finite element calculations of magnetic vector potential and vector on the magnetic field. During the source loading process, the equivalent thin wire source of the pseudo δ function was used to load the source function directly into the equation for the purpose of achieving total field calculations. This was completed to enable the calculations to be applied to any shape of the transmitting loop and undulating terrain. Then, the components of the excitation magnetic fields perpendicular to the geomagnetic fields were calculated using the rotation matrix. Finally, the NMR sensitivity function and 3D responses were calculated. The calculations of the excitation magnetic fields were verified using a uniform half-space model. The overall algorithm was tested by the nuclear magnetic responses of the layered medium. Also, a typical undulating terrain model was adopted and the complex excitation source NMR was simulated using the algorithm proposed in this study. The algorithm provided a three-dimensional forward basis for the NMR inversion in the cases of determining the electrical medium for the subsequent undulating terrain.

Numerical-field evaluation of an efficiency of a shortening of a three-phase stator winding of a cylindrical magnetic field inductor

The efficiency of cylindrical magnetic field inductors is determined by the value of the field inside their working chamber. This field is driven by a three-phase stator winding. The electrical quantities and magnetic induction in the inductor depend on its shortening. The purpose of this work is to determine the rational shortening of the stator winding. The solution of the problem is achieved on the basis of numerical calculations of magnetic fields in the FEMM software package using the finite element method. The construction of physical and geometric design models of the stator, calculations of magnetic fields and electromagnetic parameters of the inductor are automated using the created Lua script built into the FEMM program. The pictures of the distribution of magnetic field lines with diametric and shortened stator windings are given. A comparison is made between the EMF and the winding voltage, as well as the distribution of the magnetic induction over the surface of the working chamber and along the center line of the teeth with different variants of shortening the winding pitch.

CAE v1.1—A Code for the Magnetic Field Due to Arbitrary Electromagnets

The Code for the magnetic field due to Arbitrary Electromagnets (CAE) v1.1 is a feature-rich version of CAE v1.0 code to simulate the magnetic fields generated by arbitrary electromagnetic systems. The code calculates the magnetic field due to straight and circular segments of zero thickness or rectangular cross section and cylindrical wire. The magnetic field calculations use a combination of analytical and numerical integration methods based on the Biot–Savart law. The design philosophy of CAE is to reduce the complexities while generating the inputs, and provide the visuals of the given inputs as 3-D plots of the electromagnets and magnetic field components as outputs in the Excel format. The code is successfully verified with the standard examples and the EFFI implementation on BETA, ADITYA-U, and SST-1 tokamaks.

Solar Corona as Indicator of Differential Rotation of Subphotospheric Layers

In our earlier work [2–4], we proposed using the coronal magnetic field as an implicit tracer when studying the properties of differential rotation of the solar corona. At present, this is virtually the only way to study the rotation of the Sun at large heliocentric distances up to the source surface. In the present work, calculations of the coronal magnetic field have been extended over a longer time interval, till December 31, 2015. It is shown that the solar corona rotates differentially at all heliocentric distances up to the source surface. The differential rotation gradient decreases with distance. As we approach the source surface, the corona rotation becomes more rigid, but even at large heliocentric distances it remains slightly differential. We believe that the differential rotation of the solar corona reflects the rotation of deep subphotospheric layers. In this case, the behavior of the coronal rotation characteristics can be used as indicator of differential rotation of the subphotospheric layers. We have compared the changes in the coronal rotation characteristics with distance with helioseismic data and obtained a satisfactory agreement. Cycle variations in the differential rotation of subphotospheric layers have been investigated for the first time.

Magnetic Simulator Testbed for APSCO Student Small Satellite Project

The Student Small Satellite (SSS) is a university project of Asia-Pacific Space Cooperation Organization (APSCO), composed by one microsatellite (SSS-1) and two 3U CubeSats (SSS-2A and SSS-2B). Regarding SSS-1 and SSS-2A satellites, the active 3-axis magnetic control strategy has been applied in the Attitude Determination and Control System (ADCS). In this paper, the necessary study for the development of a Magnetic Simulator Testbed for the SSS-1 and SSS-2A satellites was performed using one pairs of Helmholtz coils for each axis of rotation (X, Y, Z). Each pair of coil can generate a sufficiently large and stable magnetic field that simulate the Earth’s magnetic field but with a reliable level of accuracy, to perform the ADCS test on the satellites. Matlab software was used to generate the propagation of the orbit for the satellites, to calculate the Earth’s magnetic field around that orbit and simulate a pair of Helmholtz coil in each axis of rotation to reproduce the Earth’s magnetic field using the Biot-Savart Law. The results obtained for propagation of the orbit, calculation of terrestrial magnetic field and reproduction of the magnetic field through the Magnetic Simulator Testbed, were very close to the results obtained in important researches previously consulted, giving reliability to this research and allowing an analysis to determine the real physical size that Magnetic Testbed should have. The size determined, is very close to what was expected, allowing to conclude the reliability and viability of the development of the Magnetic Testbed for APSCO SSS Project.

Magnetic Field of 1200kv Transmission Line by FEM & MATLAB

With rapid industrial and commercial growth and flourishing population, power demand is increasing rapidly. Modern methods of UHV transmission lines are important to transmit bulk amount of power more efficiently in comparison to earlier methods of transmission. 1200 KV UHV transmission line is India future and therefore forthcoming project to tackle this situation. However as line to line voltage level increases, complexity of the transmission line increases. But, with higher level of line to line voltage, complexity of transmission line increases. ROW is one of the major concerns with transmission lines. Many parameters need to take care in designing; one of them is a magnetic field distribution at surroundings of transmission line. India has initiated to expand its UHV range to 1200kv. Paper suggest magnetic field of three configurations of the 1200KV line. Horizontal and vertical configuration test lines have been installed. Analysis has been done by two methods finite element method and (Method of images) analytical method. FEM is used to solve partial differential equations. Results from both methods have been compared. 3D electric field analysis of configuration also performed. Plotted results are compared with ICNIRP standards and safety limits defined. Adverse effects of excess magnetic field is also discussed. Biological effects of electromagnetic field on people, animals and plants are also discussed. Thus paper aimed at magnetic field calculation and verification with respect to standard. It also helps to utilize less right of way. The subject is under broad development due to its advantages over lower voltage levels and holds significance in future as well.

Parameter Assessment of Beam Transport Line for Nuclear Physics Research

The IBA CP30 cyclotron was installed at the 108 Central Hospital in Hanoi, Vietnam. A proton beam with energy range from 15 to 30 MeV can be delivered by this facility. Currently, facility is mainly used for medical radioactive isotope production. There is an idea to use this accelerator for scientific research as well. For this purpose, a new beam line should be designed. A high energy resolution with minimum momentum spread is a key point for designing. A preliminary design of the beam line using matrix codes, modeling 3D optical elements, magnetic field calculations, and beam dynamics analysis is presented in this paper.

Procedure for modeling dynamic processes of the electromechanical shock absorber in a subway car

A procedure has been devised for modeling the dynamic processes in the proposed structure of an electromechanical shock absorber. Such shock absorbers can recuperate a part of the energy of oscillations into electrical energy allowing the subsequent possibility to use it by rolling stock. The procedure is based on solving the Lagrange equation for the electromechanical system. The model's features are as follows. The model takes the form of a Cauchy problem, thereby making it possible to use it when simulating the processes of shock absorber operation. Two generalized coordinates have been selected (the charge and displacement of the armature). The components of the Lagrange equation have been identified. Based on the results from magnetic field calculation and subsequent regression analysis, we have derived polynomial dependences of flux linkage derivatives for the current and linear displacement of an armature, which make it possible to identify a generalized mathematical model of the electromechanical shock absorber. The magnetic field calculations, performed by using a finite-element method, have allowed us to derive a digital model of the magnetic field of an electromechanical shock absorber. To obtain its continuous model, a regression analysis of discrete field models has been conducted. When choosing a structure for the approximating model, a possibility to analytically differentiate partial derivatives for all coordinates has been retained. Based on the results from modeling free oscillations, it was established that the maximum module value of current is 0.234 A, voltage – 52.9 V. The process of full damping of oscillations takes about 3 seconds over 4 cycles. Compared to the basic design, the amplitude of armature oscillations and its velocity dropped from 13 to 85 % over the first three cycles, indicating a greater efficiency of electromechanical shock absorber operation in comparison with a hydraulic one. The recuperated energy amounted to 3.3 J, and the scattered energy – 11.5 J.