• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.327-328
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• 2014

This paper presents a pulse density modulation (PDM) technique with a high frequency link for a dual output DC-DC converter. The proposed scheme consists of a fixed frequency AC link and independent PDM controllers for the output regulation, which provides a simple structure and higher efficiency. The simulation and experimental results are provided to show the effectiveness of the proposed method.

• Journal of IKEEE
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• v.23 no.4
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• pp.1280-1287
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• 2019

Grid-connected bidirectional PCS(Power Conditioning System) technology is a technology for implementing distributed renewable energy smart grid. And it is always charged by using power collected from solar modules and commercial grid power among vast smart grid systems, and stored when needed.It is a hybrid energy storage device that allows power to be released into the low voltage system. To this end, a PV input power converter with MPPT function, a bidirectional power converter for battery charging and discharging, and a DC Link input are output to a 3 phase 380V AC system, and if nessary, the bidirectional DC/DC converter We designed and developed a PCS with three power converter structures composed of inverters that perform battery charging. Currently, this system is applied to the site of Jeju, which is vulnerable to power outages and fire accidents.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1224-1225
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• 2011

This paper proposes a novel soft-switching interleaved boost converter composed of two shunted elementary PFC boost conversion units and an auxiliary inductor. This converter is able to turn on both the active power switches at zero voltage to reduce their switching losses and evidently raise the conversion efficiency and power factor. Since the two parallel-operated elementary boost units are identical, operation analysis and design for the converter module becomes quite simple. A laboratory test circuit is built, and the circuit operation shows satisfactory agreement with the theoretical analysis. The performance of the proposed PFC rectifier was evaluated on an experimental 300[W] PFC prototype.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.303-305
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• 2003

This paper discusses single-phase AC-DC converter that driven by binary combination at different transformer winding ratio. It has a advantage that constructs a control system simply and obtain load current of good quality without filter circuit and free from noise or isolation for lower switching frequency. Also, this has merit that can do high power capacity. In this research, study on feedback circuit that consist for load stability of AC-DC multi-level converter.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.113-114
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• 2011

PV(Photovoltaic)는 일사량 및 온도에 의해 얻을 수 있는 최대 전력이 변화하고, PV의 전압에 따라 출력 전력이 변화한다. 따라서 PV를 이용한 인버터는 최대 전력점에서 동작하게 하는 최대 전력점 추정(Maximum Power Point Tracking) 제어시스템이 필요하다. 본 논문에서는 인버터 제어에 필요한 여러가지 MPPT 기능 실험이 가능하게 하는 저가형 태양전지 시뮬레이터 시스템의 제어알고리즘을 제안한다. 이 시스템은 PV의 출력특성에 따른 출력값을 설정하고, 다양한 출력특성 변화의 실시간 변화가 가능하게 하는 새로운 알고리즘을 적용하였다. 이를 통해 PV가 설치되지 않은 곳에서 인버터의 MPPT 성능 시험이 가능하며, 실제 인버터에 구현된 P&O-MPPT와 연동하여 제안된 제어기법의 타당성을 검증하였다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.961_962
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• 2009

A novel, two-inductor, interleaved power-factor-corrected (PFC) boost converter that exhibits voltage-doubler characteristic when it operates with a duty cycle greater than 0.5 is introduced. The voltage-doubler characteristic of the proposed converter makes it quite suitable for universal-line (90~265VRMS) PFC applications. Because the proposed PFC boost rectifier operates as a voltage doubler at low line, its low-line range efficiency is greatly improved compared to that of its conventional counterpart. The performance of the proposed PFC rectifier was evaluated on an experimental 300W PFC prototype.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.3
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• pp.145-150
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• 2013

A novel AC to DC PWM converters with unity input power factor are proposed to overcome the above shortcoming. The main function of these converters is to shape the input line current to force it exactly in phase with the input AC voltage. Therefore, the input power factor can be improved to near unity and the input current harmonics can be eliminated. In this paper, half-bridge converter with two active switches and two diodes are utilized for low-cost type UPS configuration. By having only two semiconductors in the current path at any time, losses can be reduced over the conventional boost topology. Also, this converter provides controllable dc-link voltage, high power factor, and low cost type converter by simple power circuits. Simulation results show that the proposed half-bridge converter/inverter control technique can be applied to single-phase low-cost type UPS systems successfully.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.338-340
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• 2001

Power factor improved for single-phase buck-converter is studied in the paper. To sinusoidal waveform the input current with a near-unity power factor over a wide variety of operating conditions, the output capacitor is operated with voltage reversibility for the supply by arranging the auxiliary diode and power switching device. Then the output voltage is superposed on the input voltage during on time duration of power switching devices in order to minimize the input current distortion caused by the small input voltage when changing the polarity. The tested setup, using two insulated gate bipolar transistors(IGBT) and a microcomputer, is implemented and IGBT are switched with 20[kHz], which is out of the audible band. Moreover, a rigorous state-space analysis is introduced to predict the operation of the rectifier. The simulated results confirm that the input current can be sinusoidal waveform with a near-unity power factor and a satisfactory output voltage regulation can be achieved.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.341-344
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• 2001

In this paper, the characteristics of the proposed converter are show by simulation. As a result, the power factor is improved and the results show the usefulness of the proposed circuit. To improve the hard switching at turn-off of the basic circuit, the circuit using a current resonant switch is proposed. In the proposed circuit, THD of the input current is reduced to 1.8 of the basic circuit. The mechanism of the THD reduction is clarified. That is because the on period becomes shorter at the peak of the source voltage. Using the simulation, the characteristics of the output voltage, current flowing the switch, and THD of the input current are investigated by changing the resonant circuit parameters. Criteria for choosing resonant parameters of smaller THD are obtained.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2656-2658
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• 1999

This paper presents a control scheme for a three-phase PWM converter system without any voltage sensors. Two input currents and one load current are measured. In a general PWM converter system, the required AC input and DC output voltage values in order to control the converter are estimated using the differential equations of the converter from the measured input currents and load current values in the switch modes of the converter circuit. The PI controller is used as DC voltage controller and sinusoidal tracking controller which tracks directly AC input current is used as input current controller. The Proposed method is verified by simulations. This paper describes the estimation method and configuration of the controller, and discusses steady state and transient performances of the converter