Fast reconstruction of the magnetization of a Halbach magnet in EMAT using experimental measurements

2020 ◽  
Vol 64 (1-4) ◽  
pp. 905-912
Author(s):  
Ovidiu Mihalache ◽  
Toshihiko Yamaguchi
Keyword(s):  
Magnetic Flux ◽  
Flux Distribution ◽  
Theoretical Formula ◽  
Model Accuracy ◽  
3D Fem ◽  
Inverse Reconstruction ◽  
Initial Magnetization ◽  
Halbach Array ◽  
Fast Reconstruction ◽  
Reconstruction Model

The paper presents a fast and accurate algorithm to reconstruct the magnetization model of parallelepiped magnet (parts of a Halbach magnet array) or the Halbach magnet array used in an electromagnetic acoustic (EMAT) transducer. The model accuracy is validated against measurements of the magnetic flux distributions above surface of block magnets or Halbach magnet array using 2D/3D theoretical formula to compute magnetic flux distribution, validated by 2D/3D FEM simulations, and based on a non-uniform distribution of reconstructed magnetization model (using only main magnetization component). The illness of inverse reconstruction model is controlled through very small enough increments steps in an adaptive iterative algorithm but large enough increments to assure faster reconstruction, and converging to the same magnetization model of magnet blocks or Halbach array magnet, independent of the initial magnetization values.

Magnetic Flux Analysis of E-Core Hybrid Excited FSM with Various Rotor-Pole Topologies

2014 ◽  
Vol 695 ◽  
pp. 774-777
Author(s):  
Siti Nur Umira Zakaria ◽  
Erwan Sulaiman
Keyword(s):  
Magnetic Flux ◽  
High Speed ◽  
Flux Distribution ◽  
Flux Analysis ◽  
Flux Linkage ◽  
Cogging Torque ◽  
Excitation Coil ◽  
Rotor Pole ◽  
Field Excitation ◽  
Flux Path

This paper presents magnetic flux analysis of E-Core Hybrid Excited FSM with various rotor pole topologies. The stator consists of three active fluxes sources namely armature coil, field excitation coil and permanent magnet, while the rotor consists of only stack of iron which is greatly reliable for high speed operation. Initially, coil arrangement tests are examined to validate the operating principle of the motor and to identify the zero rotor position. Then, performances of 6S-4P, 6S-5P, 6S-7P and 6S-8P E-Core HEFSMs such as flux path, flux linkage, cogging torque and flux distribution are observed. As conclusion, 6S-5P and 6S-7P designs have purely sinusoidal flux waveform and less cogging torque suitable for high torque and power motor.

scholarly journals Magnetic flux distribution in locally magnetized two-layer ferromagnetic objects

2015 ◽  
pp. 8-15
Author(s):  
V.N. Kostin ◽  
◽  
O.N. Vasilenko ◽  
A.M. Porseva ◽  
A.A. Kabakova ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Flux Distribution

scholarly journals Lamination effects on a 3D model of the magnetic core of power transformers

Open Physics ◽  
2017 ◽  
Vol 15 (1) ◽  
pp. 997-1003
Author(s):  
Antonio Poveda-Lerma ◽  
Guillermo Serrano-Callergues ◽  
Martin Riera-Guasp ◽  
Manuel Pineda-Sanchez ◽  
Ruben Puche-Panadero ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Flux Density ◽  
Experimental Tests ◽  
Butt Joint ◽  
Magnetic Core ◽  
Magnetic Flux Density ◽  
Lap Joint ◽  
3D Fem ◽  
Average Value ◽  
Depth Direction

AbstractIn this paper the lamination effect on the model of a power transformer’s core with stacked E-I structure is analyzed. The distribution of the magnetic flux in the laminations depends on the stacking method. In this work it is shown, using a 3D FEM model and an experimental prototype, that the non-uniform distribution of the flux in a laminated E-I core with alternate-lap joint stack increases substantially the average value of the magnetic flux density in the core, compared with a butt joint stack. Both the simulated model and the experimental tests show that the presence of constructive air-gaps in the E-I junctions gives rise to a zig-zag flux in the depth direction. This inter-lamination flux reduces the magnetic flux density in the I-pieces and increases substantially the magnetic flux density in the E-pieces, with highly saturated points that traditional 2D analysis cannot reproduce. The relation between the number of laminations included in the model, and the computational resourses needed to build it, is also evaluated in this work.

Fast Reconstruction Method of the Stress Field for the Steam Turbine Rotor Based On Deep Fully Convolutional Network

2021 ◽  
Author(s):  
Ding Guo ◽  
Tianyuan Liu ◽  
Di Zhang ◽  
Yonghui Xie
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Stress Field ◽  
Temperature Measurement ◽  
Turbine Rotor ◽  
Convolutional Network ◽  
Fully Convolutional Network ◽  
Start Up ◽  
Fast Reconstruction ◽  
Reconstruction Model

Abstract Since it is difficult to directly measure the transient stress of a steam turbine rotor in operation, a rotor stress field reconstruction model based on deep fully convolutional network for the start-up process is proposed. The stress distribution in the rotor can be directly predicted based on the temperature of a few measurement points. First, the finite element model is used to accurately simulate the temperature and stress field of the rotor start-up process, generating training data for the deep learning method. Next, data of only 15 temperature measurement points are arranged to predict the stress distribution in critical area of the rotor surface, with the accuracy (R2-score) reaching 0.997. The time cost of the trained neural network model at a single case is 1.42s in CPUs and 0.11s in GPUs, shortened by 97.3% and 99.8% with comparison to finite element analysis, respectively. In addition, the influence of the number of temperature measurement points and the training size are discussed, verifying the stability of the model. With the advantages of fast calculation, high accuracy and strong stability, the fast reconstruction model can effectively realize the stress prediction during start-up processes, resulting in the possibility of real-time diagnosis of rotor strength in operation.

Design Optimization of Magnetic Flux Distribution for PMG by Using Response Surface Methodology

2020 ◽  
Vol 56 (6) ◽  
pp. 1-9
Author(s):  
Aslan Deniz Karaoglan ◽  
Demet Gonen Ocaktan ◽  
Ali Oral ◽  
Deniz Perin
Keyword(s):  
Response Surface Methodology ◽  
Magnetic Flux ◽  
Design Optimization ◽  
Response Surface ◽  
Flux Distribution

scholarly journals Quantitative Evaluation of Corrosion Degrees of Steel Bars Based on Self-Magnetic Flux Leakage

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 952
Author(s):  
Ding Yang ◽  
Junli Qiu ◽  
Haibo Di ◽  
Siyu Zhao ◽  
Jianting Zhou ◽  
...  
Keyword(s):  
Experimental Data ◽  
Magnetic Flux ◽  
Mathematic Model ◽  
Magnetic Flux Leakage ◽  
Rc Structures ◽  
Nondestructive Tests ◽  
Magnetization State ◽  
Initial Magnetization ◽  
Steel Bars ◽  
Flux Leakage

Corrosion is among the most critical factors leading to the failure of reinforced concrete (RC) structures. Less work has been devoted to nondestructive tests (NDT) to detect the corrosion degree of steel bars. The corrosion degree was investigated in this paper using an NDT method based on self-magnetic flux leakage (SMFL). First, a mathematic model based on magnetic dipole model was settled to simulate the SMFL of a V-shaped defect caused by corrosion. A custom 3-axis scanning device equipped with a magnetometer was used to scan the SMFL field of the 40 corroded steel bars. Experimental data obtained by scanning the 40 steel bars showed that the BZ curve of SMFL was consistent with the theoretical model analysis. Inspired by the qualitative analysis of the results, an index “K” based on a large number of experimental data was established to characterize the corrosion degree of steel bars. The experimental index “K” was linearly related to the corrosion degree α of steel bars. This paper provides a feasible approach for the corrosion degree NDT, which is not affected by the magnetization history and the initial magnetization state of steel bars.

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