• Journal of Power Electronics
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• 제15권6호
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• pp.1468-1479
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• 2015

Renewable energy resources such as wind and photovoltaic power generation systems demand a high step-up DC-DC converters to convert the low voltage to commercial grid voltage. However, the high step-up converter using a transformer has limitations of high voltage stresses of switches and diodes when the transformer winding ratio increases. Accordingly, conventional studies have been applied to series-connect multioutput converters such as forward-flyback and switched-capacitor flyback to reduce the transformer winding ratio. This paper proposes new single-ended converter topologies of an isolation type and a non-isolation type to improve power efficiency, cost-effectiveness, and output ripple. The first proposal is an isolation-type charge-pump switched-capacitor flyback converter that includes an extreme-ratio isolation switched-capacitor cell with a chargepump circuit. It reduces the transformer winding number and the output ripple, and further improves power efficiency without any cost increase. The next proposal is a non-isolation charge-pump switched-capacitor-flyback tapped-inductor boost converter, which adds a charge-pump-connected flyback circuit to the conventional switched-capacitor boost converter to improve the power efficiency and to reduce the efficiency degradation from the input variation. In this paper, the operation principle of the proposed scheme is presented with the experimental results of the 100 W DC-DC converter for verification.

• Journal of Electrical Engineering and Technology
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• 제1권3호
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• pp.343-350
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• 2006

This paper introduces a new high efficient bi-directional, non-isolated DC/DC converter. Through variations of the topology of the conventional Cuk converter, an optimum bi-directional DC/DC converter is proposed. Voltage and current in the proposed DC/DC converter are continuous. Furthermore, the efficiency in both step-up and step-down mode is improved over that of the conventional bi-directional converter. To prove the validation for the proposed converter, simulations and experiments are executed with a 300W bi-directional converter.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권11호
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• pp.663-669
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• 1999

This paper presents new self excited DC-DC converters such as Buck-boost type, Buck type and also non-inverting Buck-boost type. The proposed converters has the following advantages: simple topology, small number of circuit components, easy control method. Therefore, these converters are suitable for the portable appliances with battery source. It is especially suited for low power DC-DC conversion applications where non isolation output power is usually required. The steady state characteristics of proposed self exciting Buck-boost DC-DC converter are analysis and the result shows good agreement with experimental value. Furthermore the experimental results for 50W class self oscillating Buck-boost DC-DC converter have been obtained, which demonstrate the high efficiency and good performance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1339-1341
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• 2000

This paper presents a new PWM DC/DC converter with multi-output using single secondary winding, which has two output characteristics of the isolation and non-isolation simultaneously. The proposed converter topology is consisted of the only one switch and single secondary winding. The proposed converter, therefore, has advantages not only low cost but also high power density. Operating principal of the proposed converter topology with conventional ZVT (Zero-Voltage-Transition) is illustrated in detail and the validity of the converter is verified with several interesting simulation results.

• 전기전자학회논문지
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• 제23권3호
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• pp.962-970
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• 2019

본 논문에서는 자기구동 동기스위치를 이용한 비절연 고효율 고전압출력 DC-DC 컨버터를 제안한다. 제안하는 컨버터는 전통적인 승압형 DC-DC 컨버터 구조에 탭형 인덕터를 적용함으로써 고전압출력을 달성하며 주스위치부에 무손실 커패시터-다이오드(LCD, lossless capacitor-diode) 스너버를 적용하여 스위치 전압스트레스를 저감한다. 그리고 출력부에 다이오드 대신에 동기스위치를 적용함으로써 역회복 문제를 해결하고 고효율을 달성한다. 제안한 컨버터의 동기스위치는 자기구동방식을 이용하고 단순한 구조를 가진다. 본 논문에서는 제안한 컨버터의 동작원리를 먼저 설명하고, 후에 컨버터 프로토타입의 설계예를 제시한다. 그리고 설계된 회로파라미터로 제작된 프로토타입의 실험결과로써 제안한 컨버터의 특성을 보인다.

• 전력전자학회논문지
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• 제23권4호
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• pp.281-285
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• 2018

An isolated feedback method for measuring the inverter DC-link voltage is proposed. This method provides a simple and economical solution to inverter control systems that use a flyback converter as a controller power supply. In the proposed method, data on the DC-link voltage are acquired when the primary side voltage appears on the secondary side of the flyback transformer, thereby eliminating the need to adopt an extra signal isolation method. To solve the non-synchronization problem between the flyback converter switching and main controller sampling, the external interrupt function of the micro-controller is used as a trigger signal for the A/D conversion.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.192-194
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• 2018

In this paper a new single-stage ac-dc converter with high frequency isolation and low components count is introduced. The proposed converter is constructed using two interleaved boost circuits in the grid side and non-regulating full bridge in the DC side. An optimized switching is implemented on the two interleaved boost circuits resulting in a ripple-free grid current without a ripple cancellation network; hence very small filter inductors are used. A simple and reliable closed-loop control system is easily implemented, since the phase-shift angle is the only independent variable. Moreover, current imbalance is avoided in the presented topology without current control loop in each phase. The proposed charger charges the battery with a sinusoidal-like current instead of a constant direct current. ZVS turn on of all switches is achieved throughout the operation in both directions of power flow without any additional components.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.192-193
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• 2017

최근 석유나 석탄 에너지의 사용으로 인한 대기오염 및 미세먼지 문제가 심각해지고 있다. 따라서 신재생 에너지의 중요성이 대두대고 있고 이에 따라 정부에서도 태양광 발전이나 풍력발전 등의 비중을 확대해 나가려는 정책을 밝히고 있으며 이중 태양광 발전 시스템은 가장 주목 받고 있다. 태양광 발전의 성장에 따라 다양한 연구가 진행되어 왔으며 이 중 DC-DC 컨버터와 DC-AC 인버터로 구성된 비절연형 태양광 인버터는 회로구성이 쉽고 효율이 높아 소용량 발전에서 많은 연구가 진행되고 있다. 따라서 본 논문에서는 3kW 비절연형 태양광 발전 시스템을 구성하여 시뮬레이션을 통해 태양광 인버터의 동작을 분석하였다.