• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.320-321
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• 2018

A non-isolated high voltage gain bidirectional DC-DC converter for battery storage system has been presented in this paper. The topology is composed of boost converter and traditional SEPIC converter. The proposed converter can achieve higher voltage conversion ratio with reduced voltage and current stresses in the switches. In additional, a reduced number of components are included in this topology. The PSIM simulation is carried to validate the analysis and operation of the converter.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권1호
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• pp.67-76
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• 2012

Due to the increasing amount of applications of power electronic ac-dc converters, it is necessary to design a single-stage converter that can reliably perform both buck and boost operations. Traditionally, this can be achieved by double-stage conversion (ac/dc-dc/dc) which ultimately leads to less efficiency and a more complex control system. This paper discusses two types of modern ac-dc converters. First, the novel impedance-source ac-dc converter, abbreviated as custom Z-source rectifier, is analyzed; and then, switched inductor (SL) Z-source ac-dc converter is proposed. This paper describes the Z-source rectifiers' operating principles, the concepts behind them, and their superiorities. Analysis and simulation results show that the proposed custom Z-source rectifier can step up and step down voltage; and the main advantage of the SL Z-source ac-dc converter is its high step-up capability. Low ripple of the output dc voltage is the other advantage of the proposed converters. Finally, the SL Z-source ac-dc converter is compared with the custom Z-source ac-dc converter.

• Journal of Power Electronics
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• 제16권3호
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• pp.915-924
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• 2016

A digital self-sustained phase shift modulation (DSSPSM) strategy that allows for good soft switching and dynamic response performance in the presence of step variations is presented in this paper. The working principle, soft switching characteristics, and voltage gain formulae of a LLC converter with DSSPSM have been provided separately. Furthermore, the method for realizing DSSPSM is proposed. Specifically, some key components of the proposed DSSPSM are carefully investigated, including a parameter variation analysis, the start-up process, and the zero-crossing capture of the resonant current. The simulation and experiment results verify the feasibility of the proposed control method. It is observed that the zero voltage switching of the switches and the zero current switching of the rectifier diodes can be easily realized in presence of step load variations.

• 센서학회지
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• 제5권3호
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• pp.9-16
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• 1996

본 논문에서는 고전압 임펄스전압 발생장치의 조작에 의하여 발생하는 과도전압을 측정할 수 있는 용량성분 압기를 실현하였다. 전장센서를 이용한 과도전압측정계는 고속응답의 평판형 전장센서와 광대역 전압버퍼로 구성되었으며, 사용된 전압버퍼(LH0033)의 입력임피던스는 $10^{12}{\Omega}$ 정도로 대단히 높다. 단위계단 응답특성을 파악하기 위하여 새로운 교정방법을 제안하고, 설치조건에 따른 분압비 오차를 검토하였으며, 분압비 오차를 0.5% 이내로 하기 위한 최적설치조건을 제시하였다. 교정실험으로부터 과도전압측정계의 응답시간은 약 15.78 ns이었으며, 주파수대역은 6.37 Hz에서 27.3MHz이다. 따라서 본 측정계로 과도과전압은 물론 상용주파수전압도 신호의 일그러짐 없이 측정이 가능하였다.

• 신재생에너지
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• 제2권3호
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• pp.10-14
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• 2006

We have designed and fabricated coil structures by gold electroplating technique. The thickness, width, and length are $7{\mu}m,\;20{\mu}m$, and 1.6m, respectively. With vibrating a magnet on the surface of a fabricated electroplated coil, the micro power generator produce an alternating voltage. We have changed the vibrational frequency from 0.5Hz to 8Hz. The generated voltage was 106mV at 3Hz and 198mV at 6Hz. We have rectified and stepped up the input voltage using a quadrupler circuit. After using the step up circuit, the measured voltage was 81mV at 3Hz and 235mV at 6Hz.

• Transactions on Electrical and Electronic Materials
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• 제15권1호
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• pp.12-15
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• 2014

At the moment of transformer energization by the supply voltage, a high current called transient inrush current, which may rise to ten times the transformer full load current, could be drawn by the primary winding. This paper discusses a microcontroller circuit with the intention of controlling and limiting the inrush current for a transformer, by the method of ramping up the supply voltage feeding to the transformer primary. Simulations and the experimental results show a significant reduction of inrush current, when the ramping up voltage is applied to the three-phase transformer load. The inrush current could be almost eliminated if the correct switching step rate is chosen.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권5호
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• pp.193-200
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• 2004

In this study, we propose a small high voltage power supply, which uses a half-bridge ZCS resonant and Cockroft-Walton circuit as its ESP (Electrostatic Precipitator). This power supply transfers energy from the ZCS resonant inverter to the step-up transformer. The transformer secondary is then applied to the Cockroft-Walton circuit for generating high voltage as a discharging source of electrodes. It is highly efficient because its amount of switching losses are reduced by virtue of the current resonant half-bridge inverter, and also due to the small size, low parasitic capacitance in the transformer stage owing to the low number of winding turns of the step up transformer secondary combined with the Cockroft-Walton circuit. Using this power supply, experiments have been carried out as a function of the switching frequency and duty ratio in order to investigate the smoke removal characteristics. From these results, the best operational condition is obtained at the switching frequency of 9 kHz and the duty ratio of 50% in this ESP.

• 전력전자학회논문지
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• 제25권4호
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• pp.319-328
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• 2020

The recent use of distributed power generation systems constructed with DC-DC converters has become extremely popular owing to the rising need for environment friendly energy generation power systems. In this study, a new single-phase five-level inverter for off-grid applications constructed with a multilevel DC-DC step-up converter is proposed to boost a low-level DC voltage (36 V-64 V) to a high-level DC bus (380 V) and invert and connect them with a single-phase 230 V rms AC load. Compared with other traditional multilevel inverters, the proposed five-level inverter has a reduced number of switching devices, can generate high-quality power with lower THD values, and has balanced voltage stress for DC capacitors. Moreover, the proposed topology does not require multiple DC sources. Finally, the performance of the proposed topology is presented through the simulation and experimental results of a 400 W hardware prototype.

• 조명전기설비학회논문지
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• 제26권10호
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• pp.95-101
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• 2012

Typically, large scale power generation facilities are linked to 345kV transmission line through a step-up transformer. If the value of transient voltage by generating lightning stroke is large more than electric equipment's BIL, devices insulation is destroyed. LA(Lighting Arrester) is used as a main means of prevention. However, the installation of LA takes the constraints of installation place and expensive installation costs. Therefore, we need to carefully study whether installation of installation can be omitted and the most efficient place of installation. In this paper, we simulated the transient voltage detected by lightning stroke at each equipments in the 345kV transmission power grid by using EMTP-RV program.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.25-25
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• 2010

This paper describes the design and fabrication of a Risk Voltage Meter (RVM) which can analyze the step and touch voltages in grounding systems. The meter consists of a sine-wave power source which generates up to 300 [$V_{rms}$] in ranges of 45 [Hz]~1 [kHz], a 8 Ch. data acquisition module, and a personal computer. Also, a noise elimination method by a digital band-pass filter during measurement is proposed.