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Annual Report Conference on Electrical Insulation and Dielectric Phenomena

作者： Hua Li Yaohong Chen Fuchang Lin Fei Lv Zhiwei Li Miao Zhang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan Hubei P. R. China 430074

ISBN: (纸本)9781457709852

The metalized film capacitor can work under a high electric field due to its self-healing characteristic. But when the capacitor is charged rapidly to a specified high voltage (under a high electric field) and then it is disconnected from the power supply, a significant voltage drop will be observed, so the capacitor energy efficiency will reduce. It can be observed that the general curve of the voltage decay has a rapid initial drop and then the curve can usually be fit to a pure exponential. Firstly, this paper analyses the factors which cause the voltage decay through experimental study. The research results show that electric field strength, operating temperature and hold time play important roles in the voltage decay process. The higher the electric field or operating temperature is, the more significant the voltage drop is. If the voltage of the capacitor is maintained for a specified period of time, the voltage drop will reduce significantly. Through these experimental results, it is revealed that the voltage drop is mainly related to leakage and polarization. So the insulation resistance at various temperatures under high electric field is tested by the special technique. The results of insulation resistances are consistent with the voltage decay at various temperatures. Moreover, the interfacial polarization which exists in the charging process of metalized film capacitor is discussed. The interfacial polarization causes the rapid initial voltage decay.

关键词： Metalized Capacitors Maintaining

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Recent Advances in Research on Low Temperature Lithium Ion Batteries Power Source for Grid Equipments

Recent Advances in Research on Low Temperature Lithium Ion B...

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IEEE International Conference on Power and Power and Renewable Energy (ICPRE)

作者： Jian Wang Chen Bing Xiaojun Zhang Heming Deng Shouding Li Shun Tang State Grid Xinjiang Company Limited Electric Power Research Institute Urumqi P.R. China State Grid Electric Power Research Institute Wuhan P.R. China Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan P. R. China

ISBN: (数字)9781728145747

ISBN: (纸本)9781728145754

This paper summarized the recent developments in temperature-tolerance power supply for grid equipment, through the theoretical prediction, design synthesis and verification of key material systems, cell structure design, core mechanism and battery preparation engineering process, this report can develop batteries suitable for power source in grid equipments in low temperature regions to meet Xinjiang Power Grid. The demand for technology to achieve the leap-forward development of grid power quality services.

关键词： Electrodes Temperature Lithium Electrolytes Conductivity Lithium-ion batteries

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A Novel Physics-Assisted Genetic Algorithm (PAGA) for Decoupling Capacitor Optimization

TechRxiv

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TechRxiv 2023年

作者： Jiang, Li Zhang, Ling Tan, Shurun Li, Da Hwang, Chulsoon Fan, Jun Li, Er-Ping The Key Laboratory of Advanced Micro/Nano Electronic Devices and Smart Systems and Applications College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China The Electromagnetic Compatibility Laboratory Missouri University of Science and Technology RollaMO65409 United States ZJU-UIUC Institute Zhejiang University Haining314400 China

This article proposes a new physics-assisted genetic algorithm (PAGA) for decoupling capacitor (decap) optimization in power distribution networks (PDNs), which is, by far, the most powerful approach to efficiently minimizing the number of decaps within an enormous search space. In the proposed PAGA method, the priority of the decap ports is first determined based on their physical loop inductances. Then, an initial solution is quickly obtained by placing decaps sequentially on the port with the highest priority. Subsequently, a GA with prior physical knowledge is developed to find better decap solutions progressively. A port removal scheme that eliminates the low-priority ports and a modified mutation operation that better guides the mutation direction is proposed to accelerate the convergence of the GA. The initial solution and the proposed auxiliary schemes can significantly narrow the search space and incorporate physical knowledge into the GA, thus greatly accelerating the convergence process. Several representative state-of-the-art algorithms and commercial tools are thoroughly compared with the proposed PAGA in different application scenarios. The proposed PAGA shows remarkably better performance in efficiently finding high-quality decap solutions and exhibits strong robustness to handle real-world and large-scale problems, which brings decap optimization algorithms to a new benchmark. © 2023, CC BY.

关键词： Genetic algorithms

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Cellulose Hydrogel-Based Biodegradable and Recyclable Magnetoelectric Composites for Electromechanical Conversion

SSRN

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SSRN 2022年

作者： Hu, Sanming Zheng, Min Wang, Qi Li, Ling Xing, Jun Chen, Kun Qi, Fuyu He, Pengyu Mao, Lin Shi, Zhijun Su, Bin Yang, Guang School of Biomedical Engineering and Imaging Xianning Medical College Hubei University of Science and Technology Xianning437100 China College of Life Science and Technology Huazhong University of Science and Technology Wuhan430074 China Huazhong University of Science and Technology China State Key Laboratory of Material Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Hubei Wuhan430074 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Hubei Wuhan430074 China College of Life Sciences Henan Agricultural University Zhengzhou450002 China

Flexible electromechanical conversion devices have attracted enormous attention as energy harvesters and self-powered sensors in the fields of wearable electronics and robotics. However, current flexible devices composed of plastic polymers and metals suffer from non-degradability and limited recyclability. Herein, a biodegradable and recyclable hydrogel-based magnetoelectric (ME) composite is fabricated via introducing NdFeB magnetic particles and copper wires into the regenerated bacterial cellulose (rBC) hydrogel. The developed hydrogel-based ME composites can effectively convert the mechanical kinetic energy into electrical energy based on the principle of electromagnetic induction, which maximum voltage reaches 15 µV. In addition, degradation experiments are conducted in this work to demonstrate the hydrogel can be rapidly degraded within 3 hours under the condition of enzyme and completely natural degraded within 49 days in water, respectively. Moreover, the left NdFeB particles and copper wires can be recyclable and reused for the same devices, leaving no environmentally hazardous electronic waste. © 2022, The Authors. All rights reserved.

关键词： Iron alloys

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ACQ-to-AIE Transformation: Tuning Molecular Packing by Regioisomerization for Two-Photon NIR Bioimaging

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Angewandte Chemie 2020年第31期132卷 12922-12926页

作者： Li Y. Liu S. Ni H. Zhang H. Chuah C. Ma C. Wong K.S. Lam J.W.Y. Kwok R.T.K. Qian J. Lu X. Tang B.Z. Department of Chemistry Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction Institute for Advanced Study Department of Chemical and Biological Engineering State Key Laboratory of Molecular Neuroscience and Division of Life Science The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong HKUST-Shenzhen Research Institute No. 9 Yuexing 1st RD South Area Hi-tech Park Nanshan Shenzhen 518057 China State Key Laboratory of Modern Optical Instrumentations Centre for Optical and Electromagnetic Research College of Optical Science and Engineering Zhejiang University Hangzhou 310058 China Department of Physics The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong Department of Materials Science Fudan University Shanghai 200438 China Center for Aggregation-Induced Emission SCUT-HKUST Joint Research Institute State Key Laboratory of Luminescent Materials and Devices South China University of Technology Guangzhou 510640 China

The traditional design strategies for highly bright solid-state luminescent materials rely on weakening the intermolecular π–π interactions, which may limit diversity when developing new materials. Herein, we propose a strategy of tuning the molecular packing mode by regioisomerization to regulate the solid-state fluorescence. TBP-e-TPA with a molecular rotor in the end position of a planar core adopts a long-range cofacial packing mode, which in the solid state is almost non-emissive. By shifting molecular rotors to the bay position, the resultant TBP-b-TPA possesses a discrete cross packing mode, giving a quantum yield of 15.6±0.2 %. These results demonstrate the relationship between the solid-state fluorescence efficiency and the molecule's packing mode. Thanks to the good photophysical properties, TBP-b-TPA nanoparticles were used for two-photon deep brain imaging. This molecular design philosophy provides a new way of designing highly bright solid-state fluorophores. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

关键词： ACQ-to-AIE transformation aggregation-induced emission cross packing regioisomerization two-photon imaging

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Kinetics Mechanism on the Efficiency of C Substituting B in the Mgb 2 Tape Fabrication

SSRN

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SSRN 2023年

作者： Guo, Chen Wang, Dongliang Zhang, Xianping Han, Meng Tang, Minghui Liu, Cong Liu, Xinyuan Liu, Fang Liu, Huajun Ma, Yanwei Gan, Zizhao Key Laboratory of Applied Superconductivity Institute of Electrical Engineering Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China Institute of Electrical Engineering and Advanced Electromagnetic Drive Technology Qilu Zhongke Jinan250013 China Applied Superconductor Engineering Technology Laboratory Institute of Plasma Physics Chinese Academy of Sciences Hefei230031 China Applied Superconductivity Research Center Key Laboratory for Artificial Microstructure and Mesoscopic Physics School of Physics Peking University Beijing100081 China

Effective carbon doping is essential for MgB2 superconductors due to its enhancement on in-field critical current density. However, C-doped MgB2 samples prepared with different boron powders exhibit varying levels of C substitution efficiency, which directly affect the superconducting properties. In this article, to further investigate the factors influencing C substitution efficiency, a two-stage carbon doping process was established based on the in-situ X-ray diffraction (XRD) measurement. The process begins with the initial in-situ ternary reaction of Mg, B and C, followed by the subsequent diffusion of C into the MgB2 lattice. Through the analysis of thermodynamic equations, it can be inferred that the key factor in improving the C substitution efficiency for MgB2 is to align the activity of the B and C precursor powders, which enables a greater participation of carbon in the initial stage of the ternary reaction. According to the systematic study on nano-C doped MgB2 tapes, the C substitution efficiency in MgB2 tapes prepared using nano amorphous boron powder is notably lower compared to those prepared using micron crystalline boron powder. These findings suggest that high-activity amorphous B powder necessitates a C dopant with a lower activation energy to enhance its C substitution efficiency. © 2023, The Authors. All rights reserved.

关键词： X ray diffraction

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Efficiency Evaluation for DAB Converter with Reactive Power Minimization Strategy and Full ZVS Operation

Efficiency Evaluation for DAB Converter with Reactive Power ...

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IEEE Energy Conversion Congress and Exposition

作者： Yan Hu Yu Zhang Qing Chen Tianhui Zhang Qingxin Guan Yang Liu Yongyong Jia Jiexin Yu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wu Han China State Grid Jiangsu Electric Power Co.LTD. Nan Jing China State Grid Jiangsu Electric Power Co.LTD. Reserch Institute Nan Jing China

It is usually believed that minimizing the reactive power while maintaining the zero voltage switching (ZVS) may significantly improve the efficiency of the dual active bridge (DAB) DC-DC converters. In this paper, the reactive power and soft switching characteristics of DAB with dual-phase-shifting (DPS) are analyzed. Therefore, a global optimal control (GOC) algorithm to minimize the reactive power while maintaining full ZVS operation is proposed. The experimental verification is carried out on the 1.5 kW prototype and the efficiency is compared with single-phase-shifting (SPS). However, the experimental results show that the efficiency at light load is lower than SPS. Furthermore, a reactive power optimization control without ZVS constraints was also performed for comparison. Finally, the efficiency is evaluated for the DAB converters with reactive power minimization and ZVS.

关键词： Zero voltage switching Reactive power Optimization Minimization Inductors electromagnetics Two dimensional displays

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Modulation of Superconducting Grain Structure to Achieve High Critical Current in Ba0.6K0.4Fe2As2 Multifilament Round Wires

SSRN

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SSRN 2022年

作者： Dong, Chiheng Han, Meng Guo, Wenwen Zhang, Xianping Liu, Cong Huang, He Yao, Chao Wang, Dongliang Liu, Huajun Ma, Yanwei Key Laboratory of Applied Superconductivity Institute of Electrical Engineering Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China Institute of Electrical Engineering and Advanced Electromagnetic Drive Technology Qilu Zhongke Jinan250013 China Institute of Plasma Physics Chinese Academy of Sciences Hefei China

Iron-based superconducting wires fabricated by the powder-in-tube method are promising candidates for practical applications due to their prominent high-field performance. The morphology, compactness and alignment of the superconducting grains, which are mainly determined by the deformation and post-sintering strategy, have a large significance for the current carrying ability. Herein, we apply a novel stainless steel/silver composite architecture combined with a scalable grooved rolling process to fabricate high-performance iron-based superconducting multifilamentary round wires. Highly dense superconducting filaments are obtained without hot-isostatic-pressing. A critical current density Jc=3.02×104 A/cm2 at 4.2 K and 10 T is achieved, which is the highest value ever reported in iron-based multifilament wires. Through detailed microscopic and theoretical analysis, we conclude the deformation mechanism of Ba0.6K0.4Fe2As2 grains and propose a supercurrent transport model for iron-based superconducting wires. We suggest that higher Jc can be achieved by introducing a better grain texture. Our method provides a simple and cost-effective way to densify practical superconducting wires and is very promising to be scaled up to long wire productions. © 2022, The Authors. All rights reserved.

关键词： Iron

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Limit Cycle Phenomenon in Boost Converter

Limit Cycle Phenomenon in Boost Converter

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Annual IEEE Conference on Applied Power Electronics Conference and Exposition (APEC)

作者： Wencheng Li Wentao Wang Xuehua Wang Yuying He Xinbo Ruan Fuxin Liu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan P. R. China Wuhan Second Ship Design and Research Institute Wuhan P. R. China Jiangsu Key Laboratory of New Energy Generation and Power Conversion Nanjing University of Aeronautics and Astronautics Nanjing P. R. China

ISBN: (数字)9781728148298

ISBN: (纸本)9781728148304

Linear small-signal average model of the dc-dc converters is often used to evaluate the converter stability, where the converter instability is customarily featured by divergence. However, in fact, the linear model can hardly holistically characterize the response of the converter due to nonlinearity. Taking the nonlinear components such as saturation into account, this paper establishes an accurate mathematical model of the Boost converter, where the nonlinear saturation is modeled by dual-input describing function (DIDF). This model could successfully predict the limit cycle phenomenon rather than divergence when system is unstable. Simulation results confirm the theoretical expectation.

关键词：

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A Wideband Bidirectional Filtering Slot Antenna with Three Slots

A Wideband Bidirectional Filtering Slot Antenna with Three S...

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Antennas and Propagation & USNC/URSI National Radio Science Meeting

作者： Junyi Lyu Pengfei Lyu Yulu Hu Shenzhen Institute for Advanced Study UESTC Shenzhen P. R. China Ocean College Jiangsu University of Science and Technology Zhenjiang China National Key Laboratory of Science and Technology on Vacuum Electronics Key Laboratory of Large-Scale Electromagnetic Industrial Software Ministry of Education School of Electronic Science and Engineering University of Electronic Science and Technology of China Chengdu P. R. China

ISBN: (数字)9798350369908

ISBN: (纸本)9798350369915

In this paper, a wideband bidirectional filtering slot antenna is proposed. Conventional slot antennas have narrow bandwidth and low frequency selectivity. First, the impedance bandwidth of the slot antenna is increased by using the shorting branch feedline. Second, two parasitic slots are introduced for electronic and magnetic coupling with the driven slot, with radiating nulls on each side of the passband to increase frequency selectivity. The proposed filtering slot antenna achieves $\vert S11\vert < -10dB$ within the 4.03GHZ-5.96GHZ(38.6%), an in-band gain of 3.91-5.78 dBi and an out-of-band radiation suppression more than 13.73 dB.

关键词： Slot antennas Filtering Magnetic separation Reflector antennas Broadband antennas Passband Impedance

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