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

Authors: Ai, Mengmeng | Shan, Yi

Article Type: Research Article

Abstract: With the rapid development of UHV power transmission and transformation project in our country, the gradually increasing electromagnetic capacity and electromagnetic loads of power transformers causes serious heating of the transformers. Therefore, it is particularly important to accurately calculate its temperature rise. Based on field-circuit coupling method, this paper took a 240000 KVA, 330 KV power transformer as the research object to calculate the whole temperature rise and heat transfer characteristics. Firstly, the average velocity of fluid was gotten by three-dimensional flow field of transformer which is calculated by establishing thermal network model of the transformer, phase winding and related structures. And …then substitute it into thermal network model. The whole average temperature and temperature rise was gotten by using first law of thermodinamics and after the iteration. And according to the temperature rise test, this paper comprised and analyzed the computed results of thermal network and numerical analysis. Results showed that the error of the thermal network model was within the scope of the permit, and it was simple and quick. The method can provide basis for the future heat transfer research and temperature rise prediction of transformer. Show more

Keywords: Oil-immersed transformer, field-circuit coupling, thermal networks, temperature rise prediction

DOI: 10.3233/JAE-210157

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-18, 2022

Authors: Wu, Yaxiang | Guo, Xingjia | Yu, Hongya | Zhong, Xichun | Liu, Zhongwu | Long, Kewen

Article Type: Review Article

Abstract: Domestic induction heating shows advantages over traditional open fire heating, but the uneven temperature distribution in the pan is still one of the problems to be solved. In this work, to improve the heating uniformity of the induction cooker, the finite element analysis (FEA) is employed to investigate the relationship between the structure of induction coil and the temperature distribution in the heating pan. The results indicate that the structure of single-coil can be optimized by varying the winding turns in different positions. More uniform temperature distribution in the pan has been obtained by increasing the number of turns at …the center and edge of the coil. The advance of this design is to achieve uniform induction heating without redesigning the power source or adding an additional coil. Based on the simulation results, the refined induction coil has been fabricated and assembled into a commercial domestic induction cooker with little modification of the power supply system. A specific parameter named relative standard deviation (RSD) is proposed to define the temperature uniformity. By real-time temperature measurement, the improved heating uniformity has been demonstrated for the refined system. The present work provides a cost-effective and efficient solution to improve heating performance of domestic induction cooker. Show more

Keywords: Induction heating, single-coil, homogeneous heating, temperature distribution, finite element method

DOI: 10.3233/JAE-210046

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

Authors: Fejérvári, Lívia | Bilicz, Sándor | Gyimóthy, Szabolcs | Pávó, József | Varga, Gábor | Várallyay, Zoltán | Yamada, Yusuke | Shimura, Takahiro | Orito, Hiroshi | Azuma, Yoshifumi

Article Type: Research Article

Abstract: Litz wires consist of many individual, isolated conductor strands. Certain litz wires are fabricated by simply twisting the bundle of strands, hence a wire pitch is realized. In this paper, the ac resistance of coils made of such twisted litz wire are calculated by combining two-dimensional finite element simulation and circuit laws. In so doing, the inherently three-dimensional problem can be solved at much lower computational cost. Results are presented for the current distribution, and for the alternating current resistance of coils, validated against measured data.

Keywords: Litz wire, finite element, ac resistance, joule loss, skin effect, proximity effect

DOI: 10.3233/JAE-210205

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-11, 2022

Authors: Guo, Baocheng | Guo, Rong

Article Type: Research Article

Abstract: In this paper, we propose an order reduction method which can be applied in the approximated analytical model for linear permanent magnet machines (LPMMs). The proposed model takes the periodic boundary condition into account the Poisson and Laplace equations, hence, the analytical solution requires low harmonic orders in each subdomain. The magnetic results show that the proposed model can maintain high accuracy while taking low computational time. 2D finite element computations, as well as measurements, validate the proposed model. The proposed model in this paper can also be further applied in permanent magnet machines with high pole and slot combination, …to reduce the computational time. Show more

DOI: 10.3233/JAE-210199

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-12, 2022

Authors: Jin, Chaowu | Su, Hao | Dong, Yue | Zhou, Jin | Xu, Yuanping | Yan, Xu

Article Type: Research Article

Abstract: When the magnetic bearing rotor is working, the iron loss concentration phenomenon may occur on the rotor journal, which will cause the temperature gradient on the rotor journal and thermal unbalance. In order to study the iron loss concentration phenomenon, a multi-physics simulation method considering the magnetic-thermal coupling is proposed. Using ANSYS Maxwell for modeling and finite element analysis to obtain the causes of iron loss concentration in magnetic bearing and the influence of different parameters on the size and distribution of iron loss; using COMSOL for magnetic-thermal coupling in magnetic bearing to obtain the influence of iron loss concentration …on temperature distribution. The simulation results show that: because of the initial disturbance, the control effect of the magnetic bearing makes the magnetic field distribution on the circumference of the rotor journal uneven, resulting in the phenomenon of iron loss concentration; control current and bias current have significant influence on iron loss distribution, while bias current and speed have a significant influence on iron loss value; iron loss concentration will result in a temperature gradient on the rotor surface. The magnetic-thermal coupling finite element analysis is verified by the temperature rise detection experiment. It provides a theoretical basis and reference for the loss and thermal unbalance of magnetic bearing. Show more

Keywords: Iron loss, magnetic-thermal coupling, magnetic bearing, temperature gradient, thermal unbalance

DOI: 10.3233/JAE-220011

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-20, 2022

Authors: Wang, Gongrun | Dong, Enyuan | Wang, Yongxing | Yin, Sheng | Zhang, Liyan | Qin, Taotao

Article Type: Research Article

Abstract: In order to improve the dynamic characteristics of the contactor, this paper proposes a new dynamic displacement prediction method for contactors with constant air gap. The dynamic displacement process can be predicted by observing the flux linkage produced by the permanent magnet. The equivalent magnetic circuit model of electromagnetic force driving actuator (EMFA) is established. The formulas of dynamic flux linkage, displacement and current are deduced, and the displacement prediction of the contactor is completed. The curved surfaces of driving force, flux linkage, displacement and current are established by finite element method. The movement process of the contactor is dynamically …simulated by interpolation method. Finally, an EMFA-driven contactor is used for the experiment. Experimental results show that the new dynamic displacement prediction method is suitable for contactors with constant air gap. On the basis of sensorless control, bounce time of the contact can be effectively reduced by adjusting the PWM duty cycle and the corresponding displacement control parameters. The research in this article can be used to guide the design of future controllers. And the simulation results are consistent with the experimental results. The experiment verifies the effectiveness of the new dynamic displacement prediction method. Show more

Keywords: Contactor, actuator, constant air gap, sensorless

DOI: 10.3233/JAE-210230

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

Authors: Chen, Xiaoliang | Wei, Weizhen | Xu, Liyou | Zhang, Shuai | Zhao, Sixia

Article Type: Research Article

Abstract: To solve the problems of the Bouc-Wen model with multi-identification parameters, low accuracy, complex methods, and difficulty in implement, this study proposes a new way for parameter identification of the Bouc-Wen model of the magnetorheological (MR) damper by parameter sensitivity analysis and modified PSO algorithm. The one-at-a-time method (OAT) of local sensitivity analysis is utilized to analyze the unknown parameters in the Bouc-Wen model to complete the model simplification. Then, the modified PSO algorithm is used to identify the parameters of the simplified Bouc-Wen model. Finally, with the relationship between the currents and identified parameters, a Bouc-Wen model for current …control is constructed by the curve fitting method. The results confirm that the parameter identification efficiency achieved via the parameter sensitivity analysis is improved by 50% by reducing the parameters of the Bouc-Wen model from 8 to 4. Then, compared with the standard PSO (SPSO) algorithm, the modified one is accurate and stable, and the convergence speed is increased by 17.65% on average. At last, compared with the test data under three different sinusoidal excitations, the model’s accuracy is 89.11%, 92.56%, and 87.45%, respectively. The method proposed in this research can rapidly and accurately identify the Bouc-Wen model and lays a theoretical foundation for applying the MR damper model in vibration control. Show more

Keywords: MR damper, parameter identification, Bouc-Wen model, improved PSO, sensitivity analysis

DOI: 10.3233/JAE-210214

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-19, 2022

Authors: Ye, Kuan | Zhou, Kai | Ren, Zhigang | Zhang, Ruizhe | Li, Chunsheng | Sun, Hongyu | Huang, Songling

Article Type: Correction

DOI: 10.3233/JAE-229001

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

Authors: Su, Peng | Wang, Yiwei | Zhao, Guishu | Shen, Yi | Li, Yongjian | Zhou, Lingkang

Article Type: Research Article

Abstract: In this paper, power-sizing equations of rotor-permanent-magnet flux-switching (RPM-FS) machines are proposed and implemented, where the main decisive factors of the electromagnetic torque, namely electric loading and magnetic loading, are deduced, respectively. Although the topologies of RPM-FS machines are evolved from traditional stator-PM flux-switching machines, there are still seriously flux leakages between poles, and it is hard to derive the peak value of the air-gap flux density directly. Hence, a local simplified magnetic equivalent circuit is utilized to calculate the magnetic loading, which is crucial for the power-sizing equation. The influences of the pole-to-pole flux-leakages and harmonics in back-EMF are …considered to improve the calculated accuracy of the power-sizing equation. Consequently, the electromagnetic torque can be predicted with acceptable accuracy. The feasibility of the power-sizing equation is verified by the finite element analysis and experimental results. Show more

Keywords: Rotor-permanent-magnet, flux-switching, sizing equation, magnetic equivalent circuit

DOI: 10.3233/JAE-210232

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-10, 2022

Authors: Ruowei, Qu | Shifen, Wang | Zhengfang, Liu | Junhua, Gu | Guizhi, Xu

Article Type: Research Article

Abstract: Epilepsy is one of the most serious neurological diseases in the world. The mesial temporal lobe epilepsy (MTLE), especially hippocampal sclerosis (HS) is the most common pathological causes of epilepsy. With the development of computer visualization technology, there are many auxiliary diagnostic approaches based on deep learning algorithms. However, the traditional 2D-CNN framework can only accept single layer inputs. In such case, the associations between the brain planes are ignored, which may lead to misdiagnosis or missed diagnosis. 3D-CNN framework can accept cubes as the input of the neural network, so that network parameters will carry more structural and logical …information of the brain in the spatial domain. Therefore, this study designed a 3D-CNN framework for MTLE diagnosis in T2-FLAIR MRI images. We retrospectively collected 15 patients with the MTLE and 15 age-matched controls who underwent T2-FLAIR studies. Then, we proposed three 3D-CNN based on ResNet to identify symmetrical differences in the corresponding areas of the brain in both sides. The symmetrical cubes were combined as the inputs for the 3D-CNN framework. Performances of the proposed framework were compared with radiomics algorithms and visual assessment. The proposed 3D-CNN based on ResNet-34 performs the best among all the algorithms. Moreover, due to the non-inferiority testing for paired data, the proposed 3D-CNN frameworks based on the ResNet were not inferior to that of visual assessment which was unblinded to the clinical information. The proposed 3D-CNN framework could diagnosis MTLE in MRI images accurately and efficiently, which might be applied as a computer-assisted approach for the future diagnosis of epilepsy patients. Show more

Keywords: Epilepsy, hippocampal sclerosis, CNN, MRI, computer aided diagnosis

DOI: 10.3233/JAE-220003

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-9, 2022