International Journal of Applied Electromagnetics and Mechanics - Volume Pre-press, issue Pre-press

Authors: Ma, Yangyang | Li, Yongjian | Chen, Ruiying | Yue, Shuaichao | Sun, He

Article Type: Research Article

Abstract: With the increase in power electronic equipment in power system, the excitation of ferromagnetic materials often involves a large number of harmonics. Therefore, it is necessary to construct an accurate dynamic hysteresis model to adapt to this complicated operating state of electrical equipment. In this paper, a Hybrid Dynamic Hysteresis Model (HDHM), which can effectively characterize the harmonic excitation of materials is studied based on the Preisach model and Stacked Auto-Encoder (SAE) model. The static part of this model takes the form of the inverse Preisach model. And the Multiple Dynamic Hysteresis Model Set (MDHMS) is constructed by multiple dynamic …models of eddy currents and excess characteristics of the ferromagnetic materials. The dynamic part of the HDHM takes the form of the model structure combining the Stacked Auto-encoder and the MDHMS. The calculation results of the hysteresis loop and ferromagnetic loss in the harmonic condition of silicon steel sheet proves the validity of this model. Moreover, compared with the conventional dynamic hysteresis model, the HDHM has better accuracy and generalization ability. Show more

Keywords: Hybrid dynamic hysteresis model, the Preisach model, multiple-model set theory, ferromagnetic materials, iron loss

DOI: 10.3233/JAE-220112

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-15, 2022

Authors: Zhao, Haining | Yu, Shenbo

Article Type: Research Article

Abstract: In this paper, the distribution of the air gap magnetic field in the motorized spindle is obtained through theoretical derivation, which is verified by comparing with the finite element simulation results. Based on the original calculation of air gap magnetic field, the rotor eccentricity theory is added, and the distribution of air gap magnetic field after rotor eccentricity is obtained. The correctness of the calculation theory of eccentric air gap magnetic field is verified by the finite element simulation results. Through the electromagnetic force calculation and finite element simulation of asymmetric magnetic field in eccentric state, the influence law of …unbalanced electromagnetic force on the fatigue life of motorized spindle rotor is summarized. Show more

Keywords: Motorized spindle, rotor eccentricity, unbalanced magnetic pull, fatigue life

DOI: 10.3233/JAE-220236

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-16, 2023

Authors: Kłosowski, Grzegorz | Rymarczyk, Tomasz | Wójcik, Dariusz

Article Type: Research Article

Abstract: The main problem with any tomography is the transformation of measurements into images. It is the so-called “inverse problem,” which, due to its indeterminacy, can never be solved perfectly. An additional factor contributing to the deterioration of the quality of tomograms is measurement noise. This article shows how to denoise electrical capacitance tomography measurements using the LSTM autoencoder. The presented model is two-staged. First, the autoencoder is trained using very noisy measurements. Then, the decoder autoencoder generates a training set to using activations ofe the latent layer. In the second stage, the LSTM network is trained, which has encoder latent …layer activations at the input and pattern images at the output. The results of the experiments show that using an autoencoder to denoise the measurements improves the reconstruction quality. Show more

Keywords: Electrical tomography, industrial tomography, inverse problem, LSTM networks, autoencoders

DOI: 10.3233/JAE-230013

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-14, 2023

Authors: Permata, Diah | Widyawati, W. | Sinaga, Herman H. | Purwasih, Nining | Widiarto, Sonny

Article Type: Research Article

Abstract: Natural fiber composite becomes a necessity encountering the issue of eco-friendly materials. The application of natural fiber composite as electromagnetic interference (EMI) shielding enclosures has not been studied extensively. This study aims to investigate the performance of the coconut fiber composite as EMI shielding enclosure material. Enhancement of the electrical volume-conductivity of the composite was made by polymerization of coconut fiber with polyaniline and doping the multiwall carbon nanotubes to epoxy resin. Three types of composites were made with different weight percentages of coconut fiber: 5, 10, and 15 wt%. The highest volume-conductivity and shielding effectiveness of coconut fiber composite …are 0,0458 S/m and −7.69 dB from the highest weight percentage of coconut fiber (15 wt%). While the highest tensile strength (26.78 MPa) resulted from the lowest weight percentage (5 wt%). This study shows the coconut fiber composite could potentially be the material of EMI shielding enclosure though their electrical conductivity and tensile strength should be increased. Show more

Keywords: Coconut fiber, natural composite, enclosure, conductivity, shielding effectiveness

DOI: 10.3233/JAE-220295

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-8, 2023

Authors: Jiang, Hao | Zhang, Hongwei | Chen, Jing | Xiao, Sa | Miao, Xiren | Lin, Weiqing

Article Type: Research Article

Abstract: The top oil temperature in ultra-high voltage (UHV) reactors has attracted enormous interest due to its wide applications in fault diagnosis and insulation evaluation. In this work, the precise prediction method based on the Seq2Seq module with the convolutional block attention mechanism is proposed for the UHV reactor. To reduce the influence of vibratility and improve computational efficiency, a combination of the encoding layer and decoding layer named Seq2Seq is performed to reconstruct the complex raw data. The convolutional block attention mechanism (CBAM), composed of spatial attention and channel attention, is utilized to maximize the use of information in data. …The Seq2Seq-CBAM is established to forecast the variation tendency of the oil temperatures in the UHV reactor. The experimental results show that the proposed method achieves high prediction accuracy for the top oil temperature in both single-step and multi-step. Show more

Keywords: UHV reactor, top oil temperature, attention, convolution block attention mechanism (CBAM), online detection scenario

DOI: 10.3233/JAE-230022

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-20, 2023

Authors: Rao, Shaowei | Yang, Shiyou | Tucci, Mauro | Barmada, Sami

Article Type: Research Article

Abstract: In this contribution a methodology to diagnose transformer faults based on Dissolved Gas Analysis (DGA) by using a convolutional neural network (CNN) is proposed. The algorithm to transform the gas contents (resulting from the DGA analysis) into feature maps is introduced, and the resulting feature maps are the input of the CNN. In order to take into account the fact that the data set is imbalanced, the improved Synthetic Minority Over-Sampling Technique (SMOTE) is combined with the data cleaning technique to protect the CNN from training bias. The effect of the CNN architecture on the classification performance is also investigated …to determine the optimal CNN parameters. All the above mentioned possibilities are tested and their performance investigated; in addition, a final test on the IEC TC 10 transformer fault database validates the accuracy and the generalization potential of the proposed methodology. Show more

Keywords: Convolutional neural network, deep learning, DGA, fault diagnosis, SMOTE, transformer

DOI: 10.3233/JAE-230011

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-17, 2023

Authors: Hou, Peng | Ge, Baojun | Tao, Dajun | Pan, Bo | Zhao, Liping

Article Type: Research Article

Abstract: The linear speed of the rotor surface of high speed permanent magnet motor (HSPMM) is as high as 100 m/s, and the air friction loss on the rotor surface is much higher than that of ordinary motors, accounting for a large proportion of the total loss, and the actual air friction loss on the rotor surface is much higher than that of ordinary motors. It is extremely difficult to directly measure and verify the size of the rotor surface. At the same time, the air friction loss on the rotor surface is related to various factors such as motor speed, air …gap structure and rotor surface roughness. It is difficult to accurately calculate through theoretical analysis and analytical methods. Based on the 3D fluid field physical model, this paper analyzes the relationship between the rotor air friction loss of FeCo based HSPMM and the rotor speed, rotor geometry, surface roughness and axial wind speed. Based on HSPMM, the calculation and test method of rotor surface air friction loss are studied. Through the FeCo based HSPMM no-load test, according to the relationship between the rotor air friction loss and other losses and the motor speed, the rotor surface air friction loss can be separated from the total loss. The experimental results are consistent with the calculated values, indicating that the HSPMM rotor air friction loss calculation method based on 3D fluid field analysis is effective. Show more

Keywords: Air friction loss, 3D fluid field, Fluid mechanics, HSPMM, Loss separation

DOI: 10.3233/JAE-230030

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-14, 2023

Authors: Mikami, Ryosuke | Sato, Hayaho | Hayashi, Shogo | Igarashi, Hajime

Article Type: Research Article

Abstract: This paper proposes a multi-objective optimization method for permanent magnet motors using a fast optimization algorithm, Covariance Matrix Adaptation Evolution Strategy (CMA-ES), and deep learning. Multi-objective optimization with topology optimization is effective in the design of permanent magnet motors. Although CMA-ES needs fewer population size than genetic algorithm for single objective problems, this is not evident for multi-objective problems. For this reason, the proposed method generates training data by solving the single-objective optimization multiple times using CMA-ES, and constructs a deep neural network (NN) based on the data to predict performance from motor images at high speed. The deep NN …is then used for fast solution of multi-objective optimization problems. Numerical examples demonstrate the effectiveness of the proposed method. Show more

Keywords: Deep learning, CNN, multi-objective optimization, CMA-ES, NSGA-II, PM motor

DOI: 10.3233/JAE-230077

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-10, 2023

Authors: Rymarczyk, Tomasz | Kulisz, Monika | Kłosowski, Grzegorz

Article Type: Research Article

Abstract: This study concerns research on using electrical impedance tomography (EIT) to image moisture inside the porous walls of buildings. In order to transform the electrical measurements into the values of the reconstructed 3D images, a neural network containing the LSTM layer was used. The objective of the study was to evaluate the impact of various loss functions on the efficacy of a neural network’s learning process. During the training process, three distinct variations of the loss function were employed, namely mean squared error (MSE), Huber, and a hybrid of MSE + Huber, to attain the desired outcome. Given that the …primary focus of the study was on the loss function, the particular neural network architecture employed was deemed non-essential. In order to minimize the influence of the neural network architecture on the outcomes of the test, a comparatively uncomplicated neural model was implemented, comprising a solitary LSTM layer and a single fully connected layer. Show more

Keywords: Machine learning, neural networks, electrical tomography, moisture inspection

DOI: 10.3233/JAE-230083

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-15, 2023

Authors: Hizem, Moez | Ben Saada, Aymen | Ben Mbarek, Sofiane | Choubani, Fethi

Article Type: Research Article

Abstract: Human-Like digital models have been around for quite some time. They significantly contributed to the increase of the accuracy of the whole-body-average specific absorption rate estimations. However, the anatomical and morphological diversity between human beings has not yet been embraced by the actual anthropomorphic models for several reasons such as financial costs, excessive exposure of volunteers to electromagnetic waves, and the required number of technical experts needed to build one voxelized model. Recently, machine learning has been used to reduce the complexity of certain tasks. Yet, at least, having an anthropomorphic model per nation is still far away to achieve. …To reduce the building cost of new human-like models, we build on the success of anthropomorphic models and machine learning to derive mathematical equations that make it possible to predict the Whole-body-average SAR from low frequencies up to twice the resonance frequency without any cost and excessive electromagnetic exposure of new volunteers. The completely new machine learning based equations are applicable for any age, ethnic group, and for both genders. They depend only on the human body’s morphological (height and weight) and anatomical parameters (tissue weights). In this work, we first address the whole-body-average SAR peak and we present a set of two estimators. In second, we show that the resonance frequency is not only a function of the height of the human body, to end up with a third estimation for the resonance frequency. These completely new estimators are finally combined into a novel function that links the whole-body-average SAR to the frequency. It shows the accurate prediction for low frequencies (10 MHz) up to twice the resonance frequency. The derived estimators for the maximum WBASAR and the resonance frequencies showed better results for low frequency exposure. Show more

Keywords: SAR, exposure, frequency, voxel, anthropomorphic, dosimetry

DOI: 10.3233/JAE-230025

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-18, 2023

Authors: Du, Yunlu | Huang, Yunkai | Guo, Baocheng | Zhu, Zichong | Peng, Fei | Dong, Jianning

Article Type: Research Article

Abstract: In this article, an efficient multi-objective optimization strategy for the Halbach array permanent magnet synchronous machine (PMSM) is developed by taking into consideration the nonlinear B-H behavior of soft magnetic materials. Based on the harmonic modeling (HM) technology, the electromagnetic performances (EPs) of the Halbach array PMSM can be computed. To specifically model the local magnetic saturation, the stator teeth are separated into several annular layers, and each tooth is further divided into several regions along the tangential direction. Then, the parameters of the Halbach array PMSM are optimized utilizing combined nonlinear semi-analytical model (SAM) and non-dominated sorting genetic algorithm …II (NSGA-II). To validate the effectiveness and accuracy of the developed optimization scheme, a Halbach array prototype is then manufactured in accordance with the optimization results. The multi-objective rapid optimization strategy developed in this article, which includes but is not limited to Halbach array permanent magnet (PM) machines, serves as a reference for the design and optimization of various PM machines. Show more

Keywords: Halbach array, permanent magnet synchronous machine (PMSM), magnetic saturation, non-dominated sorting genetic algorithm II (NSGA-II)

DOI: 10.3233/JAE-230029

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-18, 2023

Authors: Li, Xinmin | Li, Feilong | Hung, Wing San Tony | Qiu, Zhengjie | Wu, Yonglong | Zhang, Runzhi

Article Type: Research Article

Abstract: Magnetic gears have attracted the attention of many scholars due to their advantages of low noise, maintenance free, high torque density and inherent overload protection. In this paper, three speed regulation methods of high power magnetic gear transmission system are summarized and proposed, and the finite element analysis of the three speed regulation methods is carried out by COMSOL Multiphysics simulation software. The results show that when the sizes of the three magnetic gears are similar, the output torque and load power of the speed regulation method of the magnetic gear using the magnetic field modulated type is the largest. …On the contrary, the axial magnetic gear with air gap length regulation method has the lowest output torque and load capacity. Compared with the other two methods, the coupling length regulation method has the minimum eddy current loss and the simple speed regulation structure, which is the most suitable for high power magnetic gear. Show more

Keywords: Magnetic gear, speed regulation method, torque, power, finite element analysis

DOI: 10.3233/JAE-230046

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-22, 2023

Authors: Fang, Hongwei | Li, Ziyan

Article Type: Research Article

Abstract: The application of coaxial magnetic gear (CMG) in wave generator instead of traditional variable speed gearbox can effectively improve torque density and reduce torque ripple. Thus, the operation principle of CMG from the perspective of magnetic field modulation is firstly analyzed in this paper. Then the air gap magnetic fields induced by high-speed and low-speed rotors are studied. And the radial height, inner diameter angle, and outer diameter angle of the modulating pieces (MPs) are optimized by using the combination of response surface method (RSM) and particle swarm optimization (PSO) algorithm to improve the torque transmission capacity of CMG. The …CMG is combined with the permanent magnet synchronous machine to get the magnetic-gear permanent magnet synchronous generator (MG-PMSG). The design feasibility of the MG-PMSG is verified from four aspects: static magnetic field analysis, no-load characteristics, load characteristics and load disturbance analysis. Show more

Keywords: Coaxial magnetic gear, magnetic-gear PMSG, torque, particle swarm optimization, parameter optimization

DOI: 10.3233/JAE-220082

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-23, 2023

Authors: Pang, Yuyi | Yu, Haitao | Wang, Yao | Che, Zhiyuan | Ali, Murad | Ye, Zhicheng

Article Type: Research Article

Abstract: A novel control strategy based on finite time control and super-twisting observer is proposed to improve the control performance and robustness for permanent magnet synchronous linear motor (PMSLM) drive system. First of all, the velocity-current single loop control which called non-cascade structure control is proposed by the finite time control, then the response velocity of the PMSLM drive system can be improved. Secondly, to improve the disturbance rejection performance, a super-twisting observer is designed to feedforward the load. Furthermore, the strictly convergence of the proposed control strategy is implemented. Finally, comparative simulations and experiments are designed on PI control, sliding …mode control, and the proposed control method. Results demonstrate that the proposed method has better robustness and control performance. Show more

Keywords: Permanent magnet synchronous linear motor, non-cascaded structure, finite-time control, super-twisting observer

DOI: 10.3233/JAE-220200

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-16, 2023