• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.362-364
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• 2006

This paper presents a novel DC-DC Converter for 3 [kW] Fuel Cell System Residential Application. Phase shifted control is employed to regulate the output voltage and achieve soft switching. The transformer leakage inductance is utilized effectively to achieve zero voltage turn on for the power semiconductor switches. The current doubler rectifier has only one diode drop. The transformer secondary winding current rating is one half the load current. The overall effciency of the converter is improved.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.1
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• pp.49-55
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• 2015

This paper proposes a 2.4 GHz RF oscillator with a very low close-in phase noise performance. This is composed of a low frequency crystal oscillator and three frequency multipliers such as two doubler (X2) and one tripler (X3). The proposed oscillator is implemented as a hybrid type circuit design using a discrete silicon bipolar transistor. The measurement results of the proposed oscillator structure show -115 dBc/Hz close-in phase noise at 10 kHz offset frequency, while only dissipating 5 mW from a 1-V supply. Its close-in phase noise level is very close to that of a low frequency crystal oscillator with little degradation of noise performance. The proposed structure which is consisted of a low frequency crystal oscillator and a frequency multiplier provides new method to implement a low power low close-in phase noise RF local oscillator.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.132-134
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• 2006

This paper presents the design and implementation of 1 kW prototype DC-DC power converter with bridge voltage-doubler suitable for small scale PEM fuel cell system and its associated control scheme. The operation principle of this converter is described using some operating waveforms and the switching mode equivalent circuits based on simulation results and a detailed circuit operation analysis and soft-switching conditions.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.549-550
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• 2011

본 논문에서는 단일 스위치 배전압 방식의 단상 PFC 회로의 제어기 설계방법을 제안한다. 이 PFC 회로는 저가형 이중변환방식 단상 UPS의 AC-DC 변환부에 사용되고는 있으나, 전압 제어기와 전류 제어기의 설계방법과 입력 역률 보상 및 입력 전류 고조파 억제 성능에 대한 연구결과가 알려지지 않았다. 제안된 방법으로 설계된 제어기들의 제어 성능과 입력 역률 및 입력 전류의 THD를 시뮬레이션을 통해서 검증하였다.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.398-399
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• 2011

본 논문에서는 단일 스위치 배전압 방식의 단상 PFC 회로의 제어기법들에 대해 기술한다. 이 PFC 회로는 저가형 이중변환방식 단상 UPS의 AC-DC 변환부에 사용할 수 있으나, 입력전류의 제어기법에 대한 연구 결과가 알려지지 않았다. 제안된 전류 제어기법들의 입력 전류 제어 성능, 입력 역률, 입력 전류의 THD를 시뮬레이션과 실험을 통해서 비교 검증하였다.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.551-552
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• 2011

본 논문에서는 단상 이중변환 UPS의 AC-DC 변환부를 위한 단일 스위치 배전압 방식의 단상 PFC 회로의 동작특성에 대해 기술한다. 이 PFC 회로는 적은 개수의 전력용 반도체를 쓰기 때문에 비용 절감에 도움이 된다. 동작 모드에 따른 회로 각부의 전압, 전류 파형과 출력 전압 제어, 입력 역률 보상, 입력 전류 제어의 THD 억제 성능을 시뮬레이션과 실험을 통해 보였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.6
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• pp.96-108
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• 2015

his study deals with a power conversion unit of an anti-start air conditioner compressor system for the commercial vehicle. In case of converter, to reduce the switching losses and current stresses of the device, applies LLC resonant topology. Transformer leakage inductance in the full-bridge converter is used for making the resonance with the capacitor of the voltage-doubler. Through this method we can increase power and decrease volume of system. Both circuit analysis and design guideline are described. So in this paper, power conversion unit is designed. 2.5kW anti-start air conditioner compressor system was implemented, and system operation and stability was verified through experiment.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.725-725
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• 2006

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.523-526
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• 2001

In this paper, we design and fabricate the high-efficiency and low-power switched-capacitor DC-DC converter. This converter consists of internal oscillator, output driver and output switches. The internal oscillator has 100kHz oscillation frequency and the output switches composed of one pMOS transistor and three nMOS transistors. According to the configuration of two external capacitors, the converter has three functions that are the Inverter, Doubler and Divider. The proposed converter is fabricated through the 0.8$\mu\textrm{m}$ 2-poly, 2-metal CMOS process. The simulation and experimental result for fabricated IC show that the proposed converter has the voltage conversion efficiency of 98% and power efficiency more than 95%.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1044-1048
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• 2001

This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance value is changed by the polarity of current or voltage. This paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit id constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is, it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduce and the power factor improve. A circuit design method is shown by experimentation and confirmed simulation. It explained that compared conventional pulse-width modulated (PWM)inverter with half pulse-width modulated (HPWM) inverter proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.