Performance evaluation of carbon nanotube yarn‑based inductors for ISM‑frequency band soft‑switching converters

Jung-Hwan Park,Kyoung-Tak Kim,Chun-Gu Lee,Mohamed Atef Tawfik,Muhammad Ehab,Muhammad Umair Munir,Ashraf Ahmed,Joung‑Hu Park 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.11

With the advancement of carbon material science, there have been attempts to apply carbon nanotubes in various engineering fields. In power electronics, application research has been conducted on using carbon nanotube (CNT) yarn in inductors, transformers, and motor windings, because CNT yarns show promising mechanical and electrical characteristics when compared with conventional conduction materials. This paper evaluates the feasibility of CNT yarn-based inductor applications with respect to higher-frequency power converter circuits, especially focusing on the ISM (Industry–Science–Medical) frequency range. Inductors are fabricated using two kinds of CNT yarns with different conductivity values. These inductors are compared with copper and lead coiled inductors, since they have a relatively high conductivity with respect to CNT yarns, and due to their popularity in the industry. The small-signal impedance data of each inductor according to the frequency variation are measured using a network analyzer, and the measurements were compared with a COMSOL simulation. One of the main results of this research is that the CNT yarn-based inductors were shown to have a better normalized AC resistance characteristic than the conventional conductor inductors, which have higher conductivity. It was found that CNT inductors have a similar AC resistance when compared to that of metallic conductors with nearly 1.85 times higher conductivity. A 100 W differential class-E resonant converter is implemented to test the inductors and to verify the small-signal measurement results. Efficiencies and thermal images are obtained at 6.78-MHz and 13.56-MHz ISM frequencies.

Single-Phase Bridgeless Zeta PFC Converter with Reduced Conduction Losses

Khan, Shakil Ahamed,Rahim, Nasrudin Abd.,Bakar, Ab Halim Abu,Kwang, Tan Chia The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2

This paper presents a new single phase front-end ac-dc bridgeless power factor correction (PFC) rectifier topology. The proposed converter achieves a high efficiency over a wide range of input and output voltages, a high power factor, low line current harmonics and both step up and step down voltage conversions. This topology is based on a non-inverting buck-boost (Zeta) converter. In this approach, the input diode bridge is removed and a maximum of one diode conducts in a complete switching period. This reduces the conduction losses and the thermal stresses on the switches when compare to existing PFC topologies. Inherent power factor correction is achieved by operating the converter in the discontinuous conduction mode (DCM) which leads to a simplified control circuit. The characteristics of the proposed design, principles of operation, steady state operation analysis, and control structure are described in this paper. An experimental prototype has been built to demonstrate the feasibility of the new converter. Simulation and experimental results are provided to verify the improved power quality at the AC mains and the lower conduction losses of the converter.

AC-Impedance Spectroscopic Analysis on the Charge Transport in CVD-Grown Graphene Devices with Chemically Modified Substrates

Min, Bok Ki,Kim, Seong K.,Kim, Seong Ho,Kang, Min-A,Noothongkaew, Suttinart,Mills, Edmund M.,Song, Wooseok,Myung, Sung,Lim, Jongsun,Kim, Sangtae,An, Ki-Seok American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.41

<P>A comprehensive study for the effect of interfacial buffer layers on the electrical transport behavior in CVD-grown graphene based devices has been performed by ac-impedance spectroscopy (IS) analysis. We examine the effects of the trap charges at graphene/SiO2 interface on the total capacitance by introducing self-assembled monolayers (SAMs). Furthermore, the charge transports in the polycrystalline graphene are characterized through the temperature-dependent IS measurement, which can be explained by the potential barrier model. The frequency-dependent conduction reveals that the conductivity of graphene is related with the mobility, which is limited by the scattering caused by charged adsorbates on SiO2 surface.</P>

Modeling and Simulation for Conducted Noise on AC/DC Converter Using SiC-Device

Wataru Kitagawa,Kohei Mitani,Yuki Kawamura,Takaharu Takeshita 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper presents method for deriving equivalent circuit of conducted noise occurred by the switching on isolated AC/DC converter. The simulation of the disturbance voltage is executed by using derived equivalent circuit. By confirming that the simulation results agree with the measurement results, the availability of proposed method is verified. The EMI filters are modeled by RLC circuit. By inserting the model, the simulation of the disturbance voltage is executed. By confirming that the simulation result agrees with the measurement result, the validity of equivalent circuit parameters is verified. In addition, the EMI filter is designed by the simulation result. The experiment with the EMI filter is executed. The noise level with the EMI filter are within the limit value (CISPR11) in all frequency ranges.

AC Conductivity and Complex Impedance of 3-wt% Li2CO3-doped (Ba0.5,Sr0.5)TiO3 Thick Films on Ag-Pd Printed Alumina Substrates

함용수,고중혁 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.41

Three (3)-wt% Li2CO3 doped (Ba0.5,Sr0.5)TiO3 thick films were prepared and sintered at a relatively low temperature (900 ℃) for electronic device applications. The thick films were prepared via a screen printing process on Ag-Pd printed alumina substrates. In this experiment, the crystalline and the electrical properties of Li2CO3-doped (Ba0.5,Sr0.5)TiO3 thick films on the Ag-Pd printed alumina substrates sintered at 900 ℃ were investigated. To investigate the electrical properties,we employed impedance spectroscopy and ac conductivity. In this study, we found that the 3-wt%Li2CO3 doped (Ba0.5,Sr0.5)TiO3 thick film exhibited perovskite and pseudo-cubic structures. Also,the relative dielectric permittivity of the 3 wt% Li2CO3 doped (Ba0.5,Sr0.5)TiO3 thick film was 149.25 at 30 ℃, and the activation energies were 0.432 and 0.326 eV at 1 and 81.57 kHz, respectively. The resistances of the grain and the grain boundary were 17.65 kΩand 40.5 kΩat 130 ℃,respectively.

Single-Phase Bridgeless Zeta PFC Converter with Reduced Conduction Losses

Shakil Ahamed Khan,Nasrudin Abd. Rahim,Ab Halim Abu Bakar,Tan Chia Kwang 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2

This paper presents a new single phase front-end ac?dc bridgeless power factor correction (PFC) rectifier topology. The proposed converter achieves a high efficiency over a wide range of input and output voltages, a high power factor, low line current harmonics and both step up and step down voltage conversions. This topology is based on a non-inverting buck-boost (Zeta) converter. In this approach, the input diode bridge is removed and a maximum of one diode conducts in a complete switching period. This reduces the conduction losses and the thermal stresses on the switches when compare to existing PFC topologies. Inherent power factor correction is achieved by operating the converter in the discontinuous conduction mode (DCM) which leads to a simplified control circuit. The characteristics of the proposed design, principles of operation, steady state operation analysis, and control structure are described in this paper. An experimental prototype has been built to demonstrate the feasibility of the new converter. Simulation and experimental results are provided to verify the improved power quality at the AC mains and the lower conduction losses of the converter.

AC Electrical Conduction of Cr-Doped SrTiO3 Thin Films

이재찬,Bach Thang Phan,김남철 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.2

The ac conductivity of Cr-doped SrTio3 thin films has been studied as a function of frequency and temperature. The Cr-doped SrTio3 thin films exhibit a single relaxation process, which is a thermally activated process. The dielectric relaxation occurs in the bulk region and is governed by hopping of charge carriers between traps, resulting in trap-controlled ac conduction.

Physico-mechanical, AC-conductivity and microstructural properties of FeCl₃ doped HPMC polymer films

Prakash, Y.,Somashekarappa, H.,Manjunath, A.,Mahadevaiah, Mahadevaiah,Somashekar, R. Techno-Press 2013 Advances in materials research Vol.2 No.1

The transition metal salt doped solid polymer electrolyte [TSPE] were prepared with HPMC as a host polymer. The virgin and doped films were prepared by solution-casting method and investigated using wide angle X-ray scattering method. Micro structural parameters like lattice strain (g%), stacking/twin faults, the average number of unit cells counted in a direction perpendicular to the Bragg's plane (hkl) spacing of (hkl) planes dhkl, crystallite size Ds, distortion width, standard deviation were determined by whole pattern powder fitting (WPPF) method, which is an extension of single order method. It is found that the crystallite size decreases with the increase in the content of $FeCl_3$. This decrease is due to increase in localized breaking of polymer network which also accounts for the amorphous nature of the material. The filler inorganic salt $FeCl_3$ acts as plasticizer. FTIR study also confirms and justifies the interaction between the polymer and in-organic salt in the matrix. Physical properties like mechanical stability and Ac conductivity in these films are in conformity with the X-ray results.

Synthesis and Characterisation of Mixed Conducting Perovskite Type Oxide and Its Electrochemical Application to Electrode Material for Solid Oxide Fuel Cell

Kim, Yu-Mi,Pyun, Su-Il,Lee, Gyoung-Ja,Kim, Ju-Sik The Korean Electrochemical Society 2007 한국전기화학회지 Vol.10 No.2

This article is concerned with synthesis, characterisation and electrochemical application of the mixed conducting perovskite type oxide to electrode materials for solid oxide fuel cell. First, this review provides a comprehensive survey of the various synthetic methods such as solid state reaction, Pechini, glycine nitrate process and sol-gel methods for the preparation of perovskite type oxide powders. Subsequently, the electrical and microstructural properties of the mixed conducting oxides were discussed in detail. Finally, as electrochemical applications of the mixed conducting perovskite type oxides to electrode materials for solid oxide fuel cell, fundamentals of theoretical ac-impedance model for porous mixed conducting electrodes were introduced. Furthermore, the ac-impedance behaviour of porous and dense mixed conducting electrodes prepared by various synthetic methods was discussed.

결함 이중 Perovskite La1/3TaO3 단결정의 유전 및 전도특성

손정호 한국결정성장학회 2020 한국결정성장학회지 Vol.30 No.6

A-자리 결함 이중 Perovskite La1/3TaO3 단결정 시편을 제작하여 10~800 K 온도범위에서 유전특성을 조사하였다. 500 K 이하에서는 상유전성 거동이 나타났으며, 550 K 이상에서 유전이상과 유전상수의 열이력(thermal hysterisis)가 나타났다. 교류전도도 측정에 의한 활성화 에너지는 560 K 이하 영역에서 1.83 eV로 가장 크며, 560~690 K 영역에서 0.35 eV, 690 K이상인 고온 영역에서 0.28 eV로 나타났다 이러한 결과로부터 500 K 이하 영역에서는 La3+-이온과 공공-자리가 무질서하게 배열하여 상유전상을 유지하며, 가장 높은 활성화 에너지를 나타낸 560 K 부근 영역에서는 La3+-이온이 공공-자리로의 전도 혹은 점프에 의한 재배열에 기인하여 유전이상이 나타난 것으로 판단된다. After the specimen of A-site defect double Perovskite La1/3TaO3 single crystal was manufactured, the dielectricproperties have been studied between the temperature range of 10 and 800 K. Under 500 K, a paraelectric behavior hasbeen shown, and above 550 K, a dielectric anomaly and a thermal history of dielectric constant has been shown. Anactivation energy by measurement of ac-conductivity has been the largest with 1.83 eV in the areas below 560 K, 0.35 eVin the areas of 560~690 K, and 0.28 eV in the areas of high temperature above 690 K. From these results, it is assumedthat in the areas below 500 K, La3+-ion and vacancy-site are arranged in disorder to maintain a paraelectric phase. And inthe areas near 560 K with the highest activation energy, a dielectric anomaly is attributes to rearrangement of La3+-ion dueto conduction to vacancy-site or jumping.