Calculation Of Magnetic Field Research Articles

Impact Computation of Electric and Magnetic Field on Farmers Working Near High Voltage Transmission Lines in Pakistan by Developing Software

In this revolutionized era, electricity has become an essential necessity of humans. People all over the world are concerned about the effects of HVTL (high voltage transmission lines) and their severe effects impacting on their health. Over the last two decades, developed countries have become increasingly concerned about an increase in electromagnetic fields, which poses health risks. The electromagnetic field emitted by HVTL will cause a low current to pass through the bodies. The electricity system produces low frequency electromagnetic field, which lead to the health hazards. The critical problem to those who are living near HVTL, therefore our fundamental task is to let them aware of the risk. Due to harmful exposures of electric and magnetic field, farmers working under HVTL or having their residences, suffering through severe effects in the form of different diseases. The main aim behind this research is to design GUI based software having two parts which helps to bring output of the electromagnetic field exposures with the help of various parameters includes different weather conditions affecting electric field, how people of different ages are being affected through it, identification of the regions need further protection by developing a proper mathematical model. Two approaches were used, one is to interface GUI with different sensors and second is user define function. On the basis of output EMF it will be able to find out the possible disease by using the data of WHO, ICNIRP and the data which is collected from surveys of different regions.

Ultra-fast Surrogate Model for Magnetic Field Computation of a Superconducting Magnet Using Multi-layer Artificial Neural Networks

Due to the inherent nonlinear and sophisticated nature of superconducting wires/tapes, magnetic field computation of superconducting magnets by means of finite element methods (FEMs) is a time-consuming and complicated procedure. Although Legendre series method (LSM) was proposed as an alternative of FEMs, LSMs are not still fast enough. In current research, a surrogate model based on multi-layer artificial neural networks (ANNs) was introduced for the first time to dramatically reduce the computation time of a magnetic resonance imaging (MRI) magnet. To do this, firstly, the data related to the magnetic field were extracted based on LSM simulations for around 5000 different coil geometries. After that, the geometries of coils were used as inputs to a semi-deep learning ANN-based model in MATLAB software package. The minimum magnetic field in diameter spherical volume, maximum and minimum of total magnetic field were considered as outputs of the model, known as field indices. Then, ANN model was trained to calculate these field indices for any coil geometry. By doing so, magnetic field indices were estimated with a high accuracy based on the target values and also with extremely higher speed, comparing to FEM and LSM. Results showed that it takes 15 to 17 s for the proposed model to calculate the field indices for 750 different geometries whereas it takes for LSM-based model about 4 h.

Estimating exposure to extremely low frequency magnetic fields near high-voltage power lines and assessment of possible increased cancer risk among Slovenian children and adolescents.

Some previous research showed that average daily exposure to extremely low frequency (ELF) magnetic fields (MF) of more than 0.3 or 0.4 μT could potentially increase risk of childhood leukaemia. To allow calculations of ELF MF around high voltage (HV) power lines (PL) for the whole Slovenia, a new three-dimensional method including precision terrain elevation data was developed to calculate the long-term average ELF MF. Data on population of Slovenian children and adolescents and on cancer patients with leukaemia's aged 0-19 years, brain tumours at age 0-29, and cancer in general at age 0-14 for a 12-year period 2005-2016 was obtained from the Slovenian Cancer Registry. According to the large-scale calculation for the whole country, only 0.5% of children and adolescents under the age of 19 in Slovenia lived in an area near HV PL with ELF MF density greater than 0.1 μT. The risk of cancer for children and adolescents living in areas with higher ELF MF was not significantly different from the risk of their peers. The new method enables relatively fast calculation of the value of low-frequency magnetic fields for arbitrary loads of the power distribution network, as the value of each source for arbitrary load is calculated by scaling the value for nominal load, which also enables significantly faster adjustment of calculated estimates in the power distribution network.

Fast Magnetic Field Approximation Method for Simulation of Coaxial Magnetic Gears Using AI

Artificial intelligence and deep learning have been widely used in recent years to explore the possibility of accelerating computation. However, it has very few applications in magnetic field calculation. This article employs a conditional generative adversarial network (cGAN) to approximate the magnetic field of a coaxial magnetic gear and calculate the magnetic torque through postprocessing. The working principle of magnetic field approximation using cGAN and the training process is introduced in this study. We adopted conditional image-to-image translation technology in cGAN and compared different loss functions and residual structures combinations. Then, we found the best combination, which can accelerate convergence, reduce errors, and improve the generator's performance. Numerical experiments have verified the effectiveness of the proposed cGAN, and the average numerical error can be as small as 1%. At the same time, its speedup ratio is as high as 200 compared to the finite element method.

Design of dipole magnets for Siam Photon Source II

Two types of dipole magnets are designed for the storage ring of Siam Photon Source II, the second synchrotron light source in Thailand. Magnetic field at the magnet center is 0.87 T, which bends a 3.0 GeV electron beam with the bending radius of 11.532 m and consequently the synchrotron radiation is generated. The first type of dipole magnet is a standard dipole with the magnet gap of 36 mm. The other type is designed for Infrared (IR) beamline with the larger magnet gap of 59 mm to accommodate a wide opening angle of IR radiation. The magnets are designed such that the operating current is the same while the turn number of magnet coils and the magnet gap are allowed to be different. Therefore, a single power supply can be used to excite all dipole magnets in the storage ring which will be connected in series. Magnet modelling and magnetic field calculation are performed in Opera-3D. The magnet poles are shimmed near the edges to improve magnetic field homogeneity to be within the requirement of 2×10−4 within the good field region. Mechanical analysis of magnet structure is performed in SOLIDWORKS and ANSYS where the maximum deformation of 18 - 23 µm is found at the magnet pole and the first-mode natural frequency is higher than 200 Hz.

Parallelization of Radia magnetostatics code

Radia 3D magnetostatics code has been used for the design of insertion devices for light sources over more than two decades. The code uses the magnetization integral approach that is efficient for solving permanent magnet and hybrid magnet structures. The initial version of the Radia code was sequential, its core written in C++ and interface in the Mathematica language. This paper describes a new Python interfaced parallel version of Radia and its applications. The parallelization of the code was implemented on C++ level, where the semi-analytical calculations of interaction matrix elements and resultant magnetic fields were parallelized using the Message Passing Interface. The parallel performance results are encouraging, particularly for magnetic field calculation post relaxation where a ∼600 speedup with respect to sequential execution was obtained. The new parallel Radia version facilitates designs of insertion devices and lattice magnets for novel particle accelerators.

Study of Electromagnetic Shielding for Reduction of Magnetic Fields Generate by Underground Power Cables via a Finite Element Techinique

Nowadays, with the development of the industries, the electrical types of equipment are used and applied widely for many different purposes. One of them is the use of power cables to transmit electricity over long distances, from generator stations to consumers. Local and global fields are usually created by the extensive presence of the types of currents following in power cables in general and underground cables in particular. Not only causes directly some unwanted effects on the body’s natural equilibrium, but electromagnetic fields can create the disturbance and cause interference with electronic devices. In this paper, a shielding plate is introduced to mitigate the local fields generated by a three phase current of underground power cables. The computation of magnetic fields is implemented with the magnetic vector potential formulations via a finite element technique. The developed method is applied to a practical problem.

Application of specialized software for calculation of magnetic field in the turns of switched reluctance motors stator windings

Background: The article describes the process of occurrence of additional losses in the extreme turns of the copper stator windings, based on physical laws. The causes of the skin effect in the stator windings of a switched reluctance motor (SRM) are presented, an assessment of the skin effect influence degree on additional losses in the SRM of medium and high power. 2D-model of the SRM sector in COMSOL Multiphysics software package is created to specify distribution of magnetic field in the SRM stator windings and to quantify the amount of additional losses. А comparison of the magnetic field distribution of the SRM configuration 12/8 obtained in the FEMM program and the SRM magnetic field distribution built in COMSOL Multiphysics software package is presented to assess the reliability of the results.
 Aim: Calculation of the magnetic field distribution in the turns of the stator winding by building a phased 2D-model of the SRM sector (pole division) in COMSOL Multiphysics software package to quantify the amount of additional losses caused by eddy currents in the windings.
 Methods: COMSOL Multiphysics software package is used to build 2D-sector of the SRM. To obtain results on the distribution of electromagnetic fields within the simulated area, finite element methods (FEM) are used to estimate income adjustments, the results are compared with calculations in the FEMM program.
 Results: The patterns of the magnetic field distribution of the SRM obtained in COMSOL Multiphysics software package and in FEMM program confirm the presence of a skin-effect in the extreme turns of the stator winding. It can reduce the energy efficiency of the SRM and cause local overheating of the winding turns. As a result of the simulation, the picture of the magnetic field distribution of the SRM obtained in the FEMM program is similar to the picture of the magnetic field distribution of the SRM obtained in COMSOL Multiphysics software package. Ratio error of the values of the magnetic induction of different parts of the SRM is 37 %. It is acceptable and it indicates the correctness of computer modeling in COMSOL Multiphysics software package.
 Conclusion: The patterns of the magnetic field distribution SRM in COMSOL Multiphysics software package and in the FEMM program confirm the presence of the skin-effect in the extreme turns of the stator winding, which will allow further research in the field of determining the numerical values of additional losses using 2D-model, and proceed from 2D-model to 3D-model of the SRM.

Volumic Eddy-Current Losses in Conductive Massive Parts with Experimental Validations

In this paper, the analytical determination of volumic eddy-current losses in rectangular-shaped conductive massive parts is presented with experimental validations. Eddy currents, as well as the resulting volumic losses, are generated by a sinusoidal spatially uniform applied magnetic field. A U-shaped electromagnetic device with a flat mobile armature (or adjustable air gap) is used to measure the eddy-current losses. The experimental device, its instrumentation, and the conductive massive parts are presented in detail in the paper. Thereafter, the magnetic field distribution applied on the conductive massive parts, which is the mean input data for the eddy-current loss model, is studied. A two-dimensional (2D) numerical model, under the FEMM software, for the magnetic field calculation was also developed. A comparative analysis between the experimental measurements and the numerical results allowed the distribution of the applied magnetic field to be accurately validated. In the final phase, the objective was to estimate the volumic eddy-current losses in rectangular-shaped aluminium conductive massive parts generated by the variation of this applied magnetic field. An analytical model, based on the Maxwell–Fourier method, for the accurate prediction of eddy-current losses has also been developed. An electromagnet with and without the conductive massive parts is characterized in terms of power consumption. By using the power conservation method (i.e., Boucherot’s theorem), the eddy-current losses could be quantified experimentally. The influence of segmentation is also studied. The analytical results are compared to the experimental test results.

Calculation of magnetic field and eddy current loss in end clamping ring of 300MVA synchronous condenser based on a novel semi‐analytical method

AbstractIt is very important to consider the eddy current reaction of the metal structure in large electric machines, which has a direct impact on the calculation results of induced current and loss. In order to solve the problem that the complex end leakage magnetic field is difficult to calculate directly, a new semi‐analytical method (NSM) considering the eddy current reaction is proposed. Firstly, the corresponding relationship between the external magnetic field and the global magnetic field of the clamping ring in two simple calculation models is obtained by the 3‐D finite element method. Then, the external magnetic field of the clamping ring in a 300MVA synchronous condenser under rated operating conditions is calculated, and the global magnetic field of the clamping ring is determined based on the obtained corresponding relationship. The eddy current density and eddy current loss of the clamping ring are calculated using the external magnetic field and the global magnetic field respectively. Finally, the calculation results were compared with the 3‐D finite element results, which verified the importance of the global magnetic field and the accuracy of the NSM.

Multi-functional sensor based on photonic crystal fiber using plasmonic material and magnetic fluid.

A unique highly sensitive photonic crystal fiber, to the best of our knowledge, is investigated based on plasmonic material and magnetic fluid (MF) for the simultaneous measurement of temperature and magnetic field sensor. The designed sensor is explored by tracing the different parameters such as birefringence, coupling length, power spectrum, and the peak wavelength of the transmission intensity. The magnetic field and temperature computation are attained simultaneously by examining the linear fitting curve and the movement of transmission peaks. The obtained sensitivity for temperature is 7.1nm/°C with an exposure range of 25°C to 100°C. In contrast, the magnetic field sensitivity is 12nm/Oe with a detection range of 160-200Oe. In addition, the resolutions are -1.245∘ C and 5.53Oe for temperature and magnetic field, respectively. Our inspected sensor is used to detect extremely low and high values of magnetic fields. The investigated structure is presented with simplification, compactness, easy implementation, and high sensitivity, which is expected to be a good foundation for the advancement of optical sensing devices in the future applications of industries, security, small grids, and environmental systems.

Electric and magnetic field calculation software in transmission lines

<span lang="EN-US">There is an interest in the biological effects of exposure to low-frequency electromagnetic fields issued by transmission lines on animals and humans. The fields generated by the lines are relevant for the design and operation of power systems. The study of the electric and magnetic fields in the transmission networks implemented commercial simulators bases on the finite element method. These commercial simulators are characterized by accuracy and high hardware and software requirements. This work presents CEM-LT, a tool that accurately precisely the electric and magnetic field in the transmission lines, with simple and intuitive handling and low processing times, making it ideal for being implemented together with optimization methods. The electric and magnetic field in the servant area for two case studies is analyzed to evaluate the accuracy and processing times. The level of accuracy is characterized by comparing the results with COMSOL obtaining errors of less than 2.4%. The case study with the highest computational requirement achieved a processing time of 3,027 seconds.</span>

Vacuum arc characteristics of an AMF–TMF composite contact with fixed AMF contacts under different opening velocities

The objective of this paper is to determine the vacuum arc characteristics of a novel axial magnetic field (AMF)–transverse magnetic field (TMF) composite contact under different opening velocities. The AMF–TMF composite contact consists of a pair of outer fixed AMF contacts and a pair of inner movable TMF contacts. Drawn arc experiments were carried out in an L–C discharging circuit with this composite contact system to observe the differences in the arc development process under different opening velocities. The opening velocity of the inner movable contact was set to 1.3, 1.8, and 2.3 m/s. The arc current was up to 20 kA rms. In the experiments, the arc behavior was recorded using a high-speed camera. The arc current of each contact and the arc voltage were measured. Then the arc characteristics, including the arc current transfer characteristics, diffused arc duration, and mental droplet distribution before zero current, were quantitatively analyzed. Furthermore, magnetic field calculation was carried out to explain why the arc characteristics are different under different opening velocities. Experimental results show that with an increase in the opening velocity from 1.3 to 2.3 m/s, the diffused arc duration before zero current increases from 1.05 to 1.75 ms when the cathode is on the fixed side and increases from 1.30 to 1.90 ms when the anode is on the fixed side. In addition, the quantity of mental droplets between contacts before zero current is less with high opening velocity. It indicates stronger short-current breaking capacity under higher opening velocity. From the simulation results, it can be seen that during the arcing period, more current transfers to the fixed AMF contact under higher opening velocity and generates a stronger AMF. It could explain the earlier diffusion of the vacuum arc column under higher opening velocity.

Calculation Method of Ship’s External Magnetic Field Based on Neural Network

In view of the difficulties in the calculation of the external magnetic field in the closed-loop degaussing of the ship, this paper analyzes the relationship between the internal and external magnetic field of the ship, and builds a neural network model accordingly to realize the calculating model between internal and external magnetic field. Aiming at the problem of insufficient training set, a data augmentation method based on the linear nature of the induced magnetic field is proposed. By using this method to expand the training set, the training speed and accuracy of the model can be improved. Through experimental verification of the steel double-layer shell model, the proposed magnetic field estimation method can accurately predict the external magnetic anomaly when the induced magnetic field and the fixed magnetic field are changed. This method not only has the advantages of fast calculation speed and high real-time performance, but also solves the long-standing problem that the fixed magnetic field changes are difficult to predict.

Analysis and Calculation of the Three-Dimensional Air-Gap Magnetic Field and Electromagnetic Torque of a Multishaft Ring-Plate Magnet Gear

A kind of multishaft ring-plate magnet gear (MRMG) structure is proposed. Because an MRMG has the characteristics of an eccentric permanent magnet gear with a small aspect ratio and large magnetic leakage at the end, there is a large deviation when using traditional 2-D FEM or an analytical method to analyze and calculate field and torque values for an MRMG. In this article, a 3-D mathematical analytical model of the MRMG eccentric air-gap magnetic field and electromagnetic torque is established, which is suitable for computer modeling. First, based on the cylindrical coordinate system of the inner and outer permanent magnet rings, the 3-D analytical models of the air-gap magnetic field of the inner and outer permanent magnet rings are established, respectively, by using the vector magnetic potential method. Then, by analyzing the position relationship between the inner and outer permanent magnet rings and their superposition angles, the radial and tangential air-gap magnetic fields of the inner and outer permanent magnet rings are superimposed according to their included angles, and a 3-D analytical model of the air-gap magnetic field and the electromagnetic torque of an MRMG is established. Because all the calculations are magnetic field integrals along the axial length of the MRMG, the magnetic field’s end effect is included in the established model, and the calculated results are more accurate than those of a 2-D FEM and analytical method (error >13%). A 3-D FEM and static loading experiment show that the model has a good accuracy (error < 2%) with the measured results and finite-element analysis, but the calculation speed of the model is faster than that of the 3-D FEM, which not only greatly shortens the calculation time but is also suitable for computer programming and is easily used to perform the MRMG analysis and optimization of different MRMG structural parameters.

Magnetic field analysis of a hybrid excitation multi-degree-of-freedom spherical motor.

A hybrid excitation multi-degree-of-freedom spherical motor (HE-MDOFSM) is designed, which can achieve MDOF motion by cooperatively controlling the excitation current in 12 sets of stator windings. The designed motor has the advantages of high power density and a large motion range. In addition, because the designed motor has an irregular three-dimensional (3D) structure, it is difficult to perform dynamic magnetic field calculations with existing methods. To solve this problem, we propose a modified 3D dynamic magnetic equivalent circuit (3DD-MEC). The proposed method establishes a node network according to the structural edge features of the motor core and the permanent magnet and calculates the reluctance of the connecting branch based on the differential principle. Moreover, a connection strategy of air-gap nodes in 3D space is formulated, and the magnetic saturation characteristics of the iron core are reflected by an iterative calculation of magnetic permeability. Using the 3DD-MEC method, the 3D dynamic magnetic field information of the HE-MDOFSM can be quickly and accurately calculated. Finally, the reliability of the method is verified by simulation and experiment, which provides a reference for improving the design optimization efficiency of HE-MDOFSM.

High-performance permanent magnet array design by a fast genetic algorithm (GA)-based optimization for low-field portable MRI

Lightweight and compact permanent magnet arrays (PMAs) are suitable for portable dedicated magnetic resonance imaging (MRI). It is worth exploring different PMA design possibilities and optimization methods with an adequate balance between weight, size, and performance, in addition to Halbach arrays and C-shaped/H-shaped magnets which are widely used. In this paper, the design and optimization of a sparse high-performance inward-outward ring-pair PMA consisting of magnet cuboids is presented for portable imaging of the brain. The design is lightweight (151kg) and compact (inner bore diameter: 270mm, outer diameter: 616mm, length: 480mm, 5-Gauss range: 1840×1840×2340mm3). The optimization framework is based on the genetic algorithm with a consideration of both field properties and simulated image quality. The resulting PMA design has an average field strength of 101.5 mT and a field pattern with a built-in linear readout gradient. Subtracting the best fit to the linear gradient target resulted in a residual deviation from the target field of 0.76mT and an average linear regression coefficient of 0.85 to the linear gradient. The required radiofrequency bandwidth is 6.9% within a field of view (FoV) with a diameter of 200mm and a length of 125mm. It has a magnetic field generation efficiency of 0.67mT/kg, which is high among the sparse PMAs that were designed for an FoV with a diameter of 200mm. The field can be used to supply gradients in one direction working with gradient coils in the other two directions, or can be rotated to encode signals for imaging with axial slice selection. The encoding capability of the designed PMA was examined through the simulated reconstructed images. The force experienced by each magnet in the design was calculated, and the feasibility of a physical implementation was confirmed. The design can offer an increased field strength, and thus, an increased signal-to-noise ratio. It has a longitudinal field direction that allows the application of technologies developed for solenoidal magnets. This proposed design can be a promising alternative to supplying the main and gradient fields in combination for dedicated portable MRI. Lastly, the design is resulted from a fast genetic algorithm-based optimization in which fast magnetic field calculation was applied and high design flexibility was feasible. Within optimization iterations, image quality metrics were used for the encoding field of a magnet configuration to guide the design of the magnet array.

Computation of transcranial magnetic stimulation electric fields using self-supervised deep learning

Electric fields (E-fields) induced by transcranial magnetic stimulation (TMS) can be modeled using partial differential equations (PDEs). Using state-of-the-art finite-element methods (FEM), it often takes tens of seconds to solve the PDEs for computing a high-resolution E-field, hampering the wide application of the E-field modeling in practice and research. To improve the E-field modeling's computational efficiency, we developed a self-supervised deep learning (DL) method to compute precise TMS E-fields. Given a head model and the primary E-field generated by TMS coils, a DL model was built to generate a E-field by minimizing a loss function that measures how well the generated E-field fits the governing PDE. The DL model was trained in a self-supervised manner, which does not require any external supervision. We evaluated the DL model using both a simulated sphere head model and realistic head models of 125 individuals and compared the accuracy and computational speed of the DL model with a state-of-the-art FEM. In realistic head models, the DL model obtained accurate E-fields that were significantly correlated with the FEM solutions. The DL model could obtain precise E-fields within seconds for whole head models at a high spatial resolution, faster than the FEM. The DL model built for the simulated sphere head model also obtained an accurate E-field whose average difference from the analytical E-fields was 0.0054, comparable to the FEM solution. These results demonstrated that the self-supervised DL method could obtain precise E-fields comparable to the FEM solutions with improved computational speed.

Investigation on torque ripple minimization in switched reluctance motor by using different techniques associated with TSF taking into account of magnetic saturation effects

In this work, three control techniques of minimization of torque ripple in SRM are proposed and compared to the classical control technic names as Hysteresis control proposed in [1]. The principle of these methods is based on the Torque Sharing Function (TSF) fixing the reference torque in each phase. In the literature review, the classical method used in the reduction of torque ripples in SRM is the TSF-Hysteresis Controller (TSF-H). The first proposed method is the TSF-Predictive control (TSF-P), here the objective is to find the voltage to be applied to the machine minimizing the error of the current through a prediction algorithm on the supply current. The second proposed method is the sliding mode control (TSF-SMC-PSO) whose parameters are optimized by the particle swarm algorithm (PSO). Finally, the third proposed method is the sliding mode controller whose parameters are optimized by fuzzy logic controller (TSF-SMFC). The finite element method (FEM) through the magnetic field calculation software FEMM was used to calculate the flux and torque in static system and to take into account magnetic saturation circuit of the SRM. The results obtained show that the TSF-SMC-PSO control methods have better performance compared to the other proposed methods mentioned above.

Nonlinear Semianalytical Model for Axial Flux Permanent-Magnet Machine

In this article, we propose a novel nonlinear semianalytical model (AM) for the magnetic field calculation of electric machines. The nonlinear properties and local saturation effect of the iron part are taken into consideration in Cartesian coordinates, which is the main contribution of the proposed model. Thus, high accuracy of electromagnetic field results can be obtained with the low computational time cost. The model is developed based on the harmonic modeling technique by solving Maxwell's equations. The detailed theoretical derivations, which use the complex Fourier series and the Cauchy product, are presented. To verify the proposed model, an axial flux permanent-magnet (PM) machine is selected to be investigated. Both finite-element model and experimental results agree well with that of the proposed model. Moreover, the nonlinear AM has potential application for other types of PM electrical motor in Cartesian coordinates, such as flat PM linear machines.