Hasil untuk "Electric apparatus and materials. Electric circuits. Electric networks"

K. Tao, Zhensheng Chen, Jiahao Yu et al.

Rapid advances in wearable electronics and mechno‐sensational human–machine interfaces impose great challenges in developing flexible and deformable tactile sensors with high efficiency, ultra‐sensitivity, environment‐tolerance, and self‐sustainability. Herein, a tactile hydrogel sensor (THS) based on micro‐pyramid‐patterned double‐network (DN) ionic organohydrogels to detect subtle pressure changes by measuring the variations of triboelectric output signal without an external power supply is reported. By the first time of pyramidal‐patterned hydrogel fabrication method and laminated polydimethylsiloxane (PDMS) encapsulation process, the self‐powered THS shows the advantages of remarkable flexibility, good transparency (≈85%), and excellent sensing performance, including extraordinary sensitivity (45.97 mV Pa−1), fast response (≈20 ms), very low limit of detection (50 Pa) as well as good stability (36 000 cycles). Moreover, with the LiBr immersion treatment method, the THS possesses excellent long‐term hyper anti‐freezing and anti‐dehydrating properties, broad environmental tolerance (−20 to 60 °C), and instantaneous peak power density of 20 µW cm−2, providing reliable contact outputs with different materials and detecting very slight human motions. By integrating the signal acquisition/process circuit, the THS with excellent self‐power sensing ability is utilized as a switching button to control electric appliances and robotic hands by simulating human finger gestures, offering its great potentials for wearable and multi‐functional electronic applications.

Kshipra Srikrishnaprabhu, Mila Lewerenz, Markus Fischer et al.

Abstract Brain‐inspired computing solutions require a suitable hardware platform, where complex operations can be realized at low power consumption. Ideally, the hardware can be reconfigured between multiple functionalities by tuning the corresponding device parameters. In this work, a three‐terminal silver–tin alloyed memristor is demonstrated, where the resistive switching characteristics can be modulated by the gate voltage. The polarity of the gate voltage determines the volatility of the device. Positive gate voltages result in primarily nonvolatile switching, while negative gate voltages facilitate primarily volatile switching. In addition, the set voltage and low resistance state can be adjusted by the magnitude of gate voltage both in the volatile and nonvolatile regimes. The dimensions of the active switching volume are 40 nm × 6 nm × 10 nm, making the design one of the most compact three‐terminal memristor. Such an ultrasmall, versatile memristive device represents a viable candidate for reconfigurable, neuromorphic hardware, where the basic building blocks can be conveniently customized to perform either synaptic or neural operations.

Hitesh Chhabra, Isidro Fernandez Garcia, Azminul Jaman et al.

ABSTRACT Strong correlation effects in transition metal oxides and their sensitivity to external stimuli in driving phase transitions have been widely explored. However, the richness of the metastable and coexisting quantum states beyond the phase transition temperature is less explored. We employ a highly strained manganite film on a twinned substrate of LaAlO3 and show that the cumulative effect of such structural disorder leads to temperature‐driven subtleties in the orbital hybridization of the coexisting ground states. This drives the film to electrical instabilities and the associated non linear transport leads to oscillatory dynamics, mimicking neurons with frequencies that are within the range of frequencies associated with brain waves. Our findings open up possibilities for on‐demand tailoring of such devices for applications in brain‐computer interfacing.

J. Ajayan, A. K. Panigrahy, S. Sen et al.

GaN-HEMTs on silicon (Si) or SiC or sapphire substrates are growing in popularity and is expected to completely transform the power electronics industry. Although GaN HEMTs operate in D-Mode by default, E-Mode operation is necessary for ease of IC design, low power consumption and safe operation. p-GaN gated HEMTs offer a breakdown voltage (V ${}_{\mathrm {BR}}$ ), transconductance (g ${}_{\mathrm {m}}$ ), power added efficiency (PAE) and ON-current (I ${}_{\mathrm {ON}}$ ) of over 2230 V, 205 mS/mm, 55.4 % and 1 A/mm, respectively, which makes them highly suitable for future RF-power switching applications. The time-dependent breakdown of the AlGaN-p-GaN/metal stack (due to avalanche multiplication) is a serious reliability concern in p-GaN HEMTs. Material defects, back gate effects, gate leakage, bias stress effects, ESD & short circuit failures, radiation effects and thermal effects are also important reliability concerns that can result in performance degradation, including current collapse, reduced breakdown voltage, increased on-resistance and device failure. Mechanisms like interface states, ion migration, and electron trapping are also crucial to the aging of p-GaN HEMTs. Understanding these reliability issues and degradation mechanisms is critical for enhancing the robustness of p-GaN HEMTs in power electronics and RF applications. Therefore, this article reviews the reliability issues and various degradation mechanisms of p-GaN gated E-Mode HEMTs such as forward/reverse bias stress effects, back gate effects, current collapse, charge trapping effects, radiation effects, short circuit (SC) & electrostatic discharge (ESD) failures and high temperature reliability issues. RON degradation, gate breakdown, PBTI and NBTI remains serious concerns in the development of p-GaN gated E-Mode HEMTs for future consumer electronics, wireless networks, industrial motors, electric vehicles and space/aeronautic applications.

Wenyu Peng, Xinling Yue, Willem D. van Driel et al.

Triboelectric nanogenerator (TENG), advantageous in high energy density and flexibility, is promising as a sustainable energy source but can hardly be used to power edge devices directly due to its high-voltage ac output and varying capacitive impedance. To address it, this work proposes a power-conditioning interface with a fully integrated dual synchronous switch harvesting on capacitors (D-SSHC) rectifier for triboelectric energy extraction. Furthermore, a full digital duty-cycle-based (DCB) maximum power point tracking (MPPT) algorithm is developed to optimize the energy harvesting efficiency with simple implementation and continuous tracking. Designed and fabricated in a 0.18-<inline-formula> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m BCD process, the proposed interface can extract energy at a maximum output voltage of 70 V. According to the measurement results, it achieves 99% MPPT efficiency and an energy extraction improvement of 598% compared to a full-bridge rectifier.

Shuai Lang, Shaoqiang Guo, Haishan Zhang et al.

Abstract Complementary metal‐oxide‐semiconductor (CMOS) technology faces challenges in achieving high performance at ultrashort gate lengths. 2D semiconductors, such as monolayer BX (X = P, As, Sb), offer promise due to their high carrier mobilities for both electrons and holes. This study employs Density Functional Theory (DFT) and the Nonequilibrium Green's Function (NEGF) method to evaluate monolayer BX as channel materials for sub‐10 nm gate‐length metal‐oxide‐semiconductor field‐effect transistors (MOSFETs) and tunnel field‐effect transistors (TFETs). Results show that monolayer BP and BAs MOSFETs exhibit high on‐state currents and bipolar symmetry, essential for balanced n‐type MOS and p‐type MOS performance. In TFET configurations, both materials achieve subthreshold swings (SS) below 60 mV dec−1, with BAs under biaxial tensile strain reaching SS values as low as 43.35 mV dec−1 for n‐type and 37.70 mV dec−1 for p‐type. These findings highlight the potential of monolayer BP and BAs to significantly reduce power consumption and improve switching speeds, making them highly competitive for next‐generation CMOS technologies and addressing key challenges in semiconductor miniaturization and performance enhancement.

Yandagkhuu Bayarsaikhan, Ichiro Omura

As reliability is growing critical in power electronics systems, preventive maintenance for power semiconductor devices is crucial for extending system lifespan and improving robustness. However, conventional time-based maintenance often increases operational costs and unexpected downtime due to significant variation and uncertainty in the power semiconductor device's lifetime. In contrast, condition-based maintenance offers an optimized supervision scheme based on real-time health monitoring, reducing unnecessary costs and increasing overall system reliability.This paper presents a practical, non-intrusive, online condition monitoring system for detecting degradations in power semiconductor devices. The developed V-I curve monitoring system accurately measures VCE(SAT)-IC curves for IGBT and VF-IF curves for power diode during the normal operation of a full-bridge inverter. A novel conduction current (IC) sensing method based on a low-cost, tiny PCB sensor and a two-stage integrator was proposed. On-state voltage (VON) is measured by a diode-based circuit, and case temperature (TC) is sensed by a thermocouple. Real-time VON-IC-TC samples are captured simultaneously with 16-bit ADCs of the microcontroller and stored in the SD card. Acquired V-I curve data is analyzed using two statistical approaches to detect bond wire and solder layer degradations. Both the residual-based fit model and the multivariate T2 outlier methods successfully detected abnormal conditions, and comparisons are made for these two approaches.

Ke Zhang, Michał Borkowski, Philipp Wucher et al.

Rajkumar Mandal, Arka Mandal, Nayan Pandit et al.

This study reports the synthesis of manganese dioxide (MnO2) nanowires via the hydrothermal method and the fabrication of high-performance memristor devices using solution-processed MnO2 nanowires. Microstructural characterizations, viz, XRD, SEM, EDAX and XPS of synthesized sample revealed highly crystalline structures of MnO2 nanowires. As synthesized MnO2 nanowires, mixed in different weight percentages with poly(methyl methacrylate) (PMMA) solution were deposited on Al electrode to form thin film memristor devices. Resistive switching with both analog and digital behaviors have been realized in Al/MnO2-PMMA/Al device by controlling the weight percentage (wt %) of MnO2 in the composite. When the MnO2 wt % in the composite was low (PMMA: MnO2 = 1:1), the device exhibited analog type switching, while, the higher concentration of MnO2 produced digital types of switching. The On/Off current ratio of the device increased gradually with increase in MnO2 wt %, reaching the highest switching ratio, ca. 106 and excellent endurance (>104 s) for PMMA:MnO2 = 1:8. Temperature dependent charge transport behavior and impedance spectroscopy was further carried out to explain the underlying resistive switching mechanism of the device.

Martina Falchi, Angelica Masi, Pierpaolo Usai et al.

Resonant inductive Wireless Power Transfer (WPT) offers a practical solution for supplying energy to consumer, industrial and medical devices. However, conventional WPT systems face severe limitations if one is interested to the dynamic and arbitrary control of the magnetic field distribution. Consequently, our paper explores the design and implementation of an electronically reconfigurable 5&#x00D7;5 magnetic metasurface for low-frequency WPT applications, operating at 3 MHz. The reconfigurable array is excited by a resonant transmitting coil operating in its near-field region. Through an analytical approach, the metasurface operation can be arbitrarily driven, obtaining the unit-cells current distribution which optimally reshapes the magnetic field for a desired application. In addition, the method also enables the precise determination of capacitive loads of each unit-cell for effectively synthetizing the metasurface response. Then, the reconfigurability process is accomplished by integrating varactor diodes within each unit-cell, providing real-time control of the currents pattern across the metasurface according to the analytical approach outputs. Finally, numerical simulations and experimental measurements on a fabricated prototype are presented, fully demonstrating the system&#x0027;s capability to efficiently switch between arbitrary configurations, either concentrating the magnetic field in specific areas or creating a uniform distribution. This dynamic adaptability addresses important challenges in WPT, such as reduction in alignment sensitivity and efficiency loss over distance, with enhanced flexibility, reliability, and safety.

Vaishali Vardhan, Subhajit Biswas, Sayantan Ghosh et al.

Abstract Ambipolar transistors facilitate concurrent transport of both positive (holes) and negative (electrons) charge carriers in the semiconducting channel. Effective manipulation of conduction symmetry and electrical characteristics in ambipolar silicon junctionless nanowire transistors (Si‐JNTs) is demonstrated using gaseous nitrogen dioxide (NO2). This involves a dual reaction in both p‐ and n‐type conduction, resulting in a significant decrease in the current in n‐conduction mode and an increase in the p‐conduction mode upon NO2 exposure. Various Si‐JNT parameters, including “on”‐current (Ion), threshold voltage (Vth), and mobility (µ) exhibit dynamic changes in both the p‐ and n‐conduction modes of the ambipolar transistor upon interaction with NO2 (concentration between 2.5 – 50 ppm). Additionally, NO2 exposure to Si‐JNTs with different surface morphologies, that is, unpassivated Si‐JNTs with a native oxide or with a thermally grown oxide (10 nm), show distinct influences on Ion, Vth, and µ, highlighting the effect of surface oxide on NO2‐mediated charge transfer. Interaction with NO2 alters the carrier concentration in the JNT channel, with NO2 acting as an electron acceptor and inducing holes, as supported by Density Functional Theory (DFT) calculations, providing a pathway for charge transfer and “pseudo” molecular doping in ambipolar Si‐JNTs.

The 2nd International Conference on Power Electronics and Electrical Engineering (P3E 2025) was successfully convened in Chongqing, China, from July 11 to 13, 2025. As a dedicated platform for disseminating cutting-edge developments in power electronics and electrical engineering, the conference drew the attention of an international cohort of researchers, practitioners, and scholars. With over 100 participants and 98 submitted papers, the conference maintained a high standard of academic quality through rigorous peer review, ultimately selecting 56 high-quality contributions for inclusion in the proceedings. The academic program featured a series of distinguished keynote presentations that illuminated current challenges and emergent innovations in the field. Prof. Noor Izzri Abdul Wahab from University Putra Malaysia delivered an insightful keynote on “Peer-to-peer Energy Trading of Networked Microgrid with Economic Analysis Using AI Techniques,” highlighting the intersection of power systems and artificial intelligence. Prof. Ismail Bin Musirin of Universiti Teknologi MARA examined survivability in modern grids through a “Self-Healing Strategy for Enhancing Power System Survivability.” Prof. Haoxi Cong from North China Electric Power University addressed the critical issue of secondary arcs in high voltage transmission lines, while Assoc. Prof. Yinzhi Lu of Chongqing Polytechnic University of Electronic Technology offered a forward-looking perspective on “Deterministic Communication in Power Electronics Systems,” shedding light on emerging communication frameworks in complex electronic systems. These keynote addresses, together with a series of focused oral presentations, enriched the conference by fostering dialogue on both theoretical foundations and engineering applications. The scope of the P3E 2025 proceedings reflects the diverse and interdisciplinary nature of current research. The accepted papers span a broad array of topics across power electronics and electrical engineering, including but not limited to converter technologies, motor drives, power transmission, system stability, electromagnetic compatibility, high-frequency power systems, microelectromechanical systems, electrical measurement techniques, and advanced materials. This comprehensive thematic coverage facilitated robust discussion on innovations in circuit design, control strategies, signal processing, and the integration of emerging technologies such as nanoelectronics and intelligent automation in power and energy systems. List of Committee Member is available in this PDF.

Xuhui Zhang, Zachary A H Goodwin, Alexis G. Hoane et al.

IL-doped alkali-metal salts, commonly known as salt-in-ionic liquids (SiILs), have drawn attention over recent years as electrolytes in batteries. SiILs are a class of highly concentrated, strongly correlated, and asymmetric electrolytes, with low volatility, low flammability, and extraordinary thermal and chemical stability. It has been reported that the transference numbers of alkali metals are negative in Li-based SiILs when the mole fraction of Li+ is low. This behavior can be explained by the formation of negatively charged ionic clusters composed of alkali metal cations and anions. On the other hand, MD simulations have also suggested a different ionic arrangement under high concentrations of salts, where a percolated ionic network can form, leading to positive transference numbers of metal cations. In this work, we have focused on the interfacial structure and behavior of Na-based SiILs on charged surfaces. Sodium trifluoromethanesulfonimide (NaTFSI) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]) have been selected as the alkali-metal salt and the IL, respectively, and systematically mixed at different molar ratios. An extended Surface Forces Apparatus (eSFA) and Atomic Force Microscopy (AFM) were employed for probing structural features such as the arrangement and layering of ions at charged surfaces, while Wide Angle X-ray Scattering (WAXS) was used to explore the bulk structure of the SiILs. The effect of water as an additive to SiILs, so called water-in-salt-in-ionic liquids (WiSILs) has also been investigated, as an additional component to tune nanostructure ionic mobility, and interfacial interactions. By understanding the properties of electric double layer (EDL) and the formation of solid electrolyte interface (SEI), we aim to provide insights to design materials for the next-generation batteries beyond Li-based chemistries to improve energy resilience.

L. Chuiko, Nataliia Tytarenko, Andriy Milenin et al.

The object of research is the process of manufacturing multicomponent vegetable semi-finished products with adjustable thickening of the mass from Jerusalem artichoke, carrot and pumpkin on an improved mobile vacuum evaporator. Traditional evaporators are characterized by high energy and metal consumption, the presence of a steam jacket with complex temperature range regulation, which leads to an increase in the cycle duration and losses of natural ingredients. The lack of mobility of traditional equipment does not allow it to be used in mobile lines of agricultural complexes and craft production, which is relevant for decentralized use of the device, for example, in front-line regions. In the course of improving the mobile vacuum evaporator, classical methods were used to analyze heat and mass transfer, determine the content and degree of preservation of useful natural ingredients in the conditions of mobile production of multicomponent semi-finished products with adjustable thickening. The design improvement is based on the use of a film-like electric heater of the radiant type, additional increase in the useful heat exchange surface due to the use of a mixer with a heating circuit and Peltier elements for secondary air recovery. Such actions contributed to increasing the resource efficiency of the technological cycle and stabilizing the temperature effect during the controlled thickening of natural masses. The duration of controlled thickening of multicomponent masses was reduced by 37%, the specific heat consumption by 15.5%, the loss of vitamin C by 21%, the preservation of inulin (94%), β-carotene (87%) and 88% preservation of polyphenols. It is the introduction of electric heating of the working chamber of the apparatus and the artificial increase in the useful heat exchange surface actually due to the mixer circuit, which is heated by 27%, which contributes to the stabilization of the temperature field. And the use of an air thermal insulation jacket allows for the recovery of secondary warm air, further increasing the resource efficiency of the technological cycle. The improvement of the apparatus contributes to the resource-saving processing of plant raw materials into polycomponent semi-finished products of high readiness with adjustable thickening, in particular within 25–45% of dry matter for further introduction into the formulations of new products. A polycomponent semi-finished product of high readiness with adjustable thickening can be used in functional drinks, baby food, confectionery fillings and meat and vegetable products. A comparison of the improved design with basic evaporators is characterized by resource efficiency, mobility for agricultural sectors in conditions of decentralized processing, for example in front-line regions.

О.Е. Кувалдин, К. В. Лицин

Главными причинами необходимости введения в эксплуатацию систем накопления энергии (СНЭ) являются избыточные траты ископаемого топлива на нужды газопоршневых или дизель генераторных установок и низкое качество электрической сети на объекте или даже аварийные отключения в связи с низкой динамикой отработки резкопеременной нагрузки генераторными установками. В таких системах СНЭ позволит вывести из работы резервную единицу генераторной установки, снизить затраты топлива и механические нагрузки на генераторное оборудование и повышение отказоустойчивости генераторных установок с последующим снижением затрат на ремонт и обслуживание. Выполнена разработка модели системы накопления энергии на базе литий-ионного аккумулятора для замкнутых электрических сетей типа буровых объектов. В работе представлен пример моделирования реального технологического объекта буровой установки длительностью в 5 дней беспрерывного снятия данных. Разработанная модель построена по принципу инкапсуляции (модульности), что позволяет адаптировать её под нужды различных металлургических объектов в области добычи и переработки сырья или иных операций металлургического производства. Разработанная модель позволят проводить предварительный расчёт обеспечения электроэнергией металлургического объекта, что повышает его эффективность работы и позволяет проводить выбор необходимого оборудования. The main reasons for the need to put energy storage systems (ESS) into operation are excessive consumption of fossil fuels for the needs of gas piston or diesel generator sets and poor quality of the electrical network at the facility or even emergency shutdowns due to the low dynamics of working off the alternating load of generator sets. In such systems, the ESS will make it possible to disable the backup unit of the generator set, reduce fuel costs and mechanical loads on generator equipment and increase the fault tolerance of generator sets, followed by a reduction in repair and maintenance costs. A model of an energy storage system based on a lithium-ion battery has been developed for closed-circuit electric networks such as drilling facilities. The paper presents an example of modeling a real technological object of a drilling rig with a duration of 5 days of continuous data collection. The developed model is based on the principle of encapsulation, which allows it to be adapted to the needs of various metallurgical facilities in the field of extraction and processing of raw materials or other operations of metallurgical production. The developed model will allow for a preliminary calculation of the supply of electricity to a metallurgical facility, which increases its efficiency and allows for the selection of necessary equipment.

Илья Викторович Наумов

Актуальность статьи обусловлена необходимостью объективной оценки уровня технического состояния электрических сетей, как одного из действенных инструментариев, лежащих в основе разработки противоаварийных мероприятий. Целью статьи является аналитическая оценка объективных условий функционирования одного из филиалов ПАО «Россети Волги» – «Ульяновских распределительных сетей» при транспорте электрической энергии по всем структурным подразделениям этой компании. В соответствии с поставленными задачами дана объективная характеристика структурно-балансовых особенностей электрических сетей компании. В качестве основных методов исследования использовались общенаучные методы статистического и численного анализа, методы теории электрических цепей и теории прогнозирования. В качестве инструментария расчетов использовались программное обеспечения Excel, MATLAB и пакеты авторских программ. Произведен анализ аварийной ситуации в сетях компании за длительный период наблюдения, установлены критерии оценки событий отказов в зависимости от величины недоотпуска электрической энергии. Проанализированы основные причины повреждаемости исследуемых электрических сетей за период 2018-2023 гг. и определено их процентное соотношение в общем количестве отказов за исследуемый интервал времени. Для визуализации расчетных данных анализа использованы технологии графических редакторов Excel и MATLAB. Полученные результаты исследований могут быть интересны руководству компании «Ульяновские распределительные сети» в качестве отправного материала при разработке комплекса противоаварийных мероприятий. Также материал статьи может представлять интерес инженерным службам других электросетевых компаний и научным работникам, занимающимся исследованиями в области повышения уровня надежности электроснабжения. The relevance of the article is due to the need for an objective assessment of the level of technical condition of electrical networks, as one of the effective tools underlying the development of emergency measures. The goal of the article is an analytical assessment of the objective operating conditions of one of the PJSC Rosseti Volga – Ulyanovsk Distribution Networks branches for the transport of electric energy in all structural divisions of this company. In accordance with the tasks set, an objective characteristic of the structural and balance features of the company’s electrical networks is given. General scientific methods of statistical and numerical analysis, methods of electrical circuit theory and forecasting theory were used as the main research methods. Excel, MATLAB and author’s software packages were used as calculation tools. An analysis of the emergency situation in the company’s networks over a long period of observation was carried out, criteria for evaluating failure events were established depending on the amount of electric energy under-supply. The main causes of damage to the studied electrical networks for the period 2018-2023 have been analyzed and their percentage ratio in the total number of failures over the studied time interval has been determined. The technologies of Excel and MATLAB graphic editors are used to visualize the calculated analysis data. The obtained research results may be interested to the management of the Ulyanovsk Distribution Networks company as a starting material for the development of a set of emergency measures. Also, the material of the article may be interested to engineering services of other electric network companies and researchers engaged in research in the field of improving the power supply reliability.

Yihao Shi, Bingchang Zhang, Jianzhong Zhao et al.

Abstract It is significant to develop stretchable electronics based on silicon materials for practical applications. Although various stretchable silicon structures have been reported, electronic systems based on them exhibit limited stretchability due to the constraints between them and polymer substrates. Here, an innovative strategy of deformation mismatch is proposed to break the constraints between silicon structures and polymers and effectively reduce the strain concentration in silicon structures. As a result, encapsulated serpentine silicon strips (S‐Si strips) achieve unprecedented stretchability, exceeding 120%. The encapsulated S‐Si strip also exhibits remarkable mechanical stability and durability, enduring 100 000 cycles of 100% stretch without fracture. The effect of key parameters, including the central angle, thickness, and width of the S‐Si strip, on the deformation mismatch is revealed through combing experiments and theoretical analysis, which will guide the rational implementation of the deformation mismatch strategy. Electrical testing showcases the strain‐insensitive nature and good electrical stability of encapsulated S‐Si strips, benefiting practical applications. This work provides a new paradigm of silicon materials with excellent stretchability and will facilitate the development of stretchable electronics.

Karim BOUAOUICHE, Yamina MENASRIA, Dalila KHALFA

Vibration signal analysis is an effective technique for detecting bearing defects, and it proposes an approach that involves signal processing methods to extract information about the defects. The initial step in the proposed approach involves dividing the signal into several components (PF) using the LMD algorithm. Subsequently, the weighted kurtosis index (WKI) values are computed, and the summation of components having WKI values higher than the average of WKI leads to the formation of a new signal containing multiple pulses that are very similar to the original signal. Then we can observe peaks at the frequencies of the bearing defects in the envelope spectrum of the new signal. Applying the proposed approach to the vibration signal available in the XJTU database shows a peak at the fault frequency of the outer ring.

Masaki Yamaguchi, Yasushi Okumura, Hiroya Nishikawa et al.

Abstract Polymer‐dispersed liquid crystals (PDLCs) with nano‐phase‐separated structures, in which nanometer‐sized liquid crystal (LC) domains are dispersed within a polymer matrix (nano‐PDLCs), are transparent solid materials whose optical properties can be modulated by applying an electric field (E‐field). Because the proportion of LC that can respond to an electric field is small, the specific surface area of the phase‐separated interface of nano‐PDLCs is larger than that of conventional PDLCs, resulting in higher drive voltages than those of conventional PDLCs. To lower the driving voltage of nano‐PDLCs, highly polar LCs (C3DIO) are used with a large dielectric anisotropy (>10000), and prepared nano‐PDLCs using DIO mixtures obtained by mixing them with related compounds as the host LC. Nano‐PDLCs employing DIO mixtures exhibit higher E‐field responsivity than those using conventional LC. In addition, the electro‐optical Kerr coefficient at visible wavelength is significantly high, reaching 10−8 m V−2. Furthermore, nano‐PDLCs using the DIO mixture exhibit a memory effect in which the induced birefringence remains even after the removal of the in‐plane E‐field. Memorized birefringence can be erased by heating or applying an E‐field perpendicular to the substrate surface. Nano‐PDLCs using a DIO mixture can be rewritable electro‐birefringence‐responsive materials that can memorize arbitrary birefringence values.

B. Bayarkhuu, B. Bat-Ochir, B. Dugarjav et al.

This study proposes a practical output current measurement system in a three-phase inverter with a single printed circuit board (PCB) Rogowski coil sensor inserted in the bus between the DC-link capacitor and the power semiconductor module. This system demonstrates its advantage over conventional output current sensors, such as the Hall effect current sensors, in terms of the size, weight, operation temperature and cost. The system can be applied to 6-in-1 power modules as it does not require sensors in the inverter phase legs.In our previous works, we have developed a method called “envelope tracking”, which is used in this system as well. This method traces the switching current instead of the output current to reproduce the output current signal in real-time. Envelope tracking successfully reproduced the output current waveform for single phase inverters under certain conditions. However, a large error is observed in the three-phase inverter demonstration under a high switching frequency (narrow pulse) or when the switching of different phases overlap each other. These errors must be completely suppressed to implement the system for feedback control in three-phase inverters.In this study, a new analog basis output current waveform reproduction system is introduced to suppress the above mentioned errors. This system is implemented in a three-phase insulated-gate bipolar transistor (IGBT) inverter and successfully reproduces the output current with a single PCB sensor inserted between a 6-in-1 IGBT power module and DC-link capacitor, operating under a switching frequency of 3.5–7.0 kHz and output current of 6 A with DC-link voltage of 150 V.