• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.259-261
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• 2008

The electronic products such as laptop PC, cellular phone, robots and etc. need the DC power source. Recently, the secondary battery is frequently used as the portable DC power source and it needs forming process. In this paper, we proposed the bidirectional converter that the battery can be charged with high power factor and the discharged energy is regenerated into AC power source. In the charging mode, the converter acts as the boost rectifier. And the AC input current is controlled in phase with the AC input voltage. As a result, the power factor is improved nearly to unity. In the discharging mode, the DC power of battery wasted in resistor is regenerated to the AC bus line. Finally, the validity of the proposed bidirectional converter is verified by computer simulations and experimentation.

• 전력전자학회논문지
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• 제26권3호
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• pp.222-226
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• 2021

To comply with CE marking requirements, the electromagnetic compatibility (EMC) and low-voltage directive (LVD) tests are conducted on the sub-racks of International Thermonuclear Experimental Reactor (ITER) AC/DC converters and bypass switches. The EMC tests consist of a series of tests, including the electromagnetic interference test, the electromagnetic field immunity test, and the rapid transient burst immunity test. In the LVD test, the electric shock protection test, the xcessive temperature limit and heat resistance of equipment tests, and the fire spread prevention test are performed. This work presents and reviews the European Directive for EMC/LVD and introduces the methods of EMC and LVD tests for the sub-racks of AC/DC converters and bypass switches. It also evaluates the test method and results to meet the European Directive requirements for CE marking. The sub-racks of ITER AC/DC converters and bypass switches successfully pass the EMC and LVD tests.

• 한국전자파학회논문지
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• 제22권8호
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• pp.805-808
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• 2011

본 논문에서는 220 V의 AC 전원을 공급받아 13.56 MHz의 RF 신호를 출력하는 고효율, 고출력 Class E 전력송신기를 설계하였다. 송신기는 AC-DC 변환기와 class E 전력 증폭기로 구성된다. 설계된 AC-DC 변환기는 220V/60 Hz의 가정용 전원을 공급 받아서 약 290 V의 DC 전압을 출력한다. 이때, AC-DC 변환기는 98.03 %의 매우 높은 변환 효율을 가진다. 변환 효율을 최대로 하기 위하여 별도의 DC-DC 변환기를 사용하지 않고, AC-DC 변환기의 출력 전압을 주 전력 증폭기의 드레인 바이어스 전압으로 사용하였다. 또한, class E 전력 증폭기의 전력손실을 최소화하기 위해 high-Q 인덕터를 제작하였다. 측정 결과, 13.56 MHz에서 동작하는 class E 전력 증폭기는 최대 출력 전력 323.6 Watt에서 84.2 %의 PAE(Power-Added Efficiency)를 가진다. AC-DC 변환기를 포함한 class E 전력 송신기는 323.6 Watt에서 82.87 %의 매우 높은 효율 특성을 나타낸다.

• Journal of Power Electronics
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• 제11권6호
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• pp.897-903
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• 2011

Many voltage sag compensators have been introduced, including the traditional dynamic voltage restorer (DVR), which requires an energy storage device but is inadequate for compensating deep and long-duration voltage sags. The AC-AC sag compensators introduced next do not require a storage device and they are capable of compensating voltage sags. This type of compensator needs an AC-AC converter to regulate the output voltage. Presented in this paper is a three-phase PWM-switched autotransformer voltage sag compensator based on an AC-AC converter that uses a proposed detection technique and PWM voltage control as a controller. Its effectiveness and capability in instantly detecting and compensating voltage sags were verified via MATLAB/Simulink simulations and further investigated through a laboratory prototype developed with a TMS320F2812 DSP as the main controller.

• 전력전자학회논문지
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• 제24권3호
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• pp.207-214
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• 2019

In this study, discrete-time domain analysis is proposed to investigate the input current of a buck AC/DC light-emitting diode (LED) driver. The buck power factor correction converter can operate in both discontinuous conduction mode (DCM) and continuous conduction mode (CCM). Two discontinuous and two continuous conduction operating modes are possible depending on which event terminates the conduction of the main switch in a switching cycle. All four operating modes are considered in the discrete-time domain analysis. The peak current-mode control with slope compensation is used to design a low-cost AC/DC LED driver. A slope compensation design of the buck AC/DC LED driver is described on the basis of a discrete-time domain analysis. Experimental results are presented to confirm the usefulness of the proposed analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.300-302
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• 2008

This paper will discuss the steps in building a wind farm and the modelling of AC power system for wind power generation. And take the JeJu island for an example, with its good wind power energy resource, the most important factor for a wind farm is a good power system interconnection to decrease the power loss including the transmission loss as less as possible. So in this paper, after the JEJU wind energy analysis, we will mainly discuss the development of the modelling on JEJU AC power system by using PSCAD. And also for using the real data of the wind power in the simulation, the modelling of the JeJu power system in 2011 will also be presented in this paper.

• Journal of Power Electronics
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• 제18권6호
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• pp.1634-1641
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• 2018

This study focuses on a high-performance direct active and reactive power controller design that is successfully applicable to three-phase pulse width modulation (PWM) AC/DC converters used in renewable distributed energy generation systems. The proposed controller can overcome the sluggish transient dynamic response of conventional controllers to rapid power command changes. Desired active and reactive powers can be thoroughly obtained at the end of each PWM period through a deadbeat solution. The proposed controller achieves an exact nonlinear cross-coupling decoupling of system power without using a predefined switching table or bang/bang hysteresis control. A graphical and analytical analysis that naturally leads to a control voltage vector selection is provided to confirm the finding. The proposed control strategy is evaluated on a 3 kW PWM AC/DC converter in the simulation and experiment.

• 조명전기설비학회논문지
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• 제21권4호
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• pp.19-27
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• 2007

This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit incorporating boost H-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switch mode equivalent circuits and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft-switching(ZVS) operation ranges, and the power dissipation as compared with those of the conventional type high frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation(PWM) and pulse density modulation(PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.

• Journal of Power Electronics
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• 제16권5호
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• pp.1894-1903
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• 2016

In general, electrolytic capacitors are used to reduce power pulsations on PV-panels. However, this can reduce the reliability of the PV AC-module system, because electrolytic capacitors have a shorter lifetime than PV-panels. In addition, PV-panels generate irregular power and inject it into the grid because the output power of a PV-panel depends on the surrounding conditions such as irradiation and temperature. To solve these problems, a grid-connected photovoltaic (PV) AC-module with active power decoupling and energy storage is proposed. A parallel bi-directional converter is connected to the AC module to reduce the output power pulsations of PV-panels. Thus, the electrolytic capacitor can be replaced with a film capacitor. In addition, the irregular output power due to the surrounding conditions can be regulated by using a parallel energy storage circuit. To maintain the discontinuous conduction mode at low irradiation, the frequency control method is adopted. The design method of the proposed converter and the operation principles are introduced. An experimental prototype rated at 125W was built to verify the performance of the proposed converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.518-522
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• 2001

In recent years, natural energy has attracted growing interest because of environmental concerns. Many studies have been focused on photovoltaic power generation systems because of the ease of use in urban areas. On the conventional system, many photovoltaic modules (PV modules) are connected in series in order to obtain the sufficient DC-bus voltage for generating AC output voltage at the inverter circuit. However, the total generation power on the PV modules sometimes decreases remarkably because of the shadows that partially cover the PV modules. In order to overcome this drawback, an AC module strategy is proposed. On this system, a small power DC-AC utility interactive inverter is mounted on each PV module individually and the inverter operates so as to generate the maximum power from the corresponding PV module. This paper presents a novel flyback-type utility interactive inverter circuit suitable for AC module systems. The feature of the proposed system are, (1) small in volume and light in weight, (2) stable AC current injection, (3) enabling a small DC capacitor. The effectiveness of the proposed system is clarified through the simulation and the experiments.