• 조명전기설비학회논문지
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• 제22권4호
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• pp.35-45
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• 2008

본 논문에서는 대용량 출력에 적합한 Three-Level 컨버터에 대하여 논하였다. 전력 변환 시스템에서 에너지의 저장, 변환, 전기적 절연 및 필터 등을 위한 자성체의 적절한 설계는 매우 중요하다. 제안된 Three-Level 컨버터는 출력단 인덕터와 변압기의 결합을 통하여 자성체의 수를 저감하였다. 본 연구에서는 Three-Level 컨버터에서 자기회로 해석을 기반으로한 릴럭턴스 모델을 제안하고자 한다. 또한, 단일 코어 변압기 결선에 의한 2차측 정류방식에 대하여 논하고자 한다. 본 연구에서는 IGBT를 사용하여 입력 540[V], 출력 48[V], 3[kW]급 시스템을 제작했으며 40[kHz]에서 실험하였다.

• Journal of Power Electronics
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• 제15권3호
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• pp.652-659
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• 2015

This paper presents a new hybrid soft switching dc-dc converter with a low circulating current and high circuit efficiency. The proposed hybrid converter includes two sub-converters sharing two power switches. One is a three-level PWM converter and the other is a LLC converter. The LLC converter and the three-level converter share the lagging-leg switches and extend the zero-voltage switching (ZVS) range of the lagging-leg switches from nearly zero to full load since the LLC converter can be operated at f_sw (switching frequency) $\approx$ f_r (series resonant frequency). A passive snubber is used on the secondary side of the three-level converter to decrease the circulating current on the primary side, especially at high input voltage and full load conditions. Thus, the conduction losses due to the circulating current are reduced. The output sides of the two converters are connected in series. Energy can be transferred from the input voltage to the output load within the whole switching period. Finally, the effectiveness of the proposed converter is verified by experiments with a 1.44kW prototype circuit.

• 전력전자학회논문지
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• 제22권1호
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• pp.36-43
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• 2017

This paper describes a hybrid multi-output three-level DC/DC converter suitable for a wide, high-input voltage range of an auxiliary power supply for a high-power photovoltaic generating system. In a high-power photovoltaic generating system, the solar panel output voltage depends on solar radiation quantity and varies from 450Vdc to 1100Vdc. The proposed hybrid multi-output three-level DC/DC converter, which is an auxiliary power supply, would be used as power source for control printed circuit boards and relay and cooling fans in a high-power photovoltaic generating system. The proposed multi-output ($24V_{DC}/30A$, $230V_{DC}/5A$) hybrid three-level boost converter, which uses an energy recovery snubber, is controlled by variable-frequency and phase-shifted modulations and can achieve zero-voltage switching with all operating conditions of input voltage and load range. Experimental results of a 2kW prototype are evaluated and implemented to verify the performance of the proposed converter.

• 전력전자학회논문지
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• 제23권6호
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• pp.424-432
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• 2018

This study presents a single-phase single-stage three-level AC/DC converter with a wide controllable output voltage. The proposed AC/DC converter is designed to extend the application of e-mobility, such as electric vehicles. The single-stage converter integrates a PFC converter and a three-level DC/DC converter, operates at a fixed frequency, and provides a wide controllable output voltage (approximately 200-430Vdc) with high efficiencies over a wide load range. In addition, the input boost inductors operate in a discontinuous mode to improve the input power factor. The switching devices operate with ZVS, and the converter's THD is small, especially at full load. The feasibility of the proposed converter is verified by the experimental results of a 1.5 kW prototype.

• Journal of Power Electronics
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• 제16권2호
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• pp.447-454
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• 2016

A single-ended primary-inductor converter (SEPIC) features low input current ripple and output voltage up/down capability. However, the switching devices in a two-level SEPIC suffer from high voltage stresses and switching losses. To cope with this drawback, this study proposes a three-level SEPIC that uses a low voltage-rated switch and thus achieves better switching performance compared with the two-level SEPIC. The three-level SEPIC can reduce switch voltage stresses and switching losses. The converter operation and control method are described in this work. The experimental results for a 500 W prototype converter are also discussed. Experimental results show that unlike the two-level SEPIC, the three-level SEPIC achieves improved power efficiency with balanced capacitor voltages.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.227-231
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• 2001

A new primary-side-assisted zero-voltage and zero-current switching (ZVZCS) three-level DC-DC converter with flying capacitor is proposed. The three-level converters are promising in high voltage applications, and ZVZCS is a very effective means for reducing switching losses. The proposed DC-DC converter uses only one auxiliary transformer and two diodes to obtain ZCS for the inner leg. It has a simple and robust structure, and offers soft-switching capability even in short-switching conditions. The proposed converter was verified by experiments in a 6KW prototype designed for communication applications and operating at 100kHz.

• Journal of Power Electronics
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• 제14권6호
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• pp.1189-1196
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• 2014

A modular multilevel-clamped composited multilevel converter ($M-MC^2$) is proposed. $M-MC^2$ enables topology reconfiguration, power device reuse, and composited clamping. An advanced five-level converter ($5L-M-MC^2$) is derived from the concept of $M-MC^2$. $5L-M-MC^2$ integrates dual three-level T-type modules and one three-level neutral point clamped module. This converter can also integrate dual three-level T-type modules and one passive diode module by utilizing the device reuse scheme. The operation principle and SPWM modulation are discussed to highlight converter performance. The proposed $M-MC^2$ is comprehensively compared with state-of-the-art five-level converters. Finally, simulations and experimental results are presented to validate the effectiveness of the main contributions of this study.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.122-125
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• 2004

This paper presents the loss analysis comparison for Three-Level Converter and Full-Bridge converter. The result of the analysis is verified with 2.5kW prototype.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1069-1071
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• 2003

This paper presents the loss analysis comparison for Three-Level Converter and Full-Bridge converter. The result of the analysis is verified with 2.5kW prototype.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.164-168
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• 2004

A Zero-Voltage-Switching(ZVS) Three-Level Converter realizes ZVS for the switches with the use of the leakage inductance(or external resonant inductance) and the output capacitors of the switches, however; the rectifier diodes suffer from recovery which results in oscillation and voltage spike. In order to solve this problem, this paper proposes a novel ZVS Three-Level converter, which introduces two clamping diodes to the basic Three-Level converter to eliminate the oscillation and clamp the rectified voltage to the reflected input voltage.