• Proceedings of the KSR Conference
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• 2005.05a
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• pp.836-842
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• 2005

This paper presents a power supply of railway signal system using a Z-source inverter. The Z-source inverter overcomes the conceptual and theoretical barriers and limitations of the tradition voltage-source inverter and current-source inverter and provides novel power conversion concept. The Z-source inverter is a Buck-Boost inverter that has a wide range of obtainable voltage.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.6
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• pp.291-297
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• 2003

This paper presents a current-source-inverter based on a buck-boost configuration and its application for residential photovoltaic system. The proposed circuit has five switches. Among them, only one switch acts as chopping, and the other determine the polarity of output; therefore, it can reduce the switching loss. Because the input inductor current is operated on the discontinuous conduction mode, high power factor can be achieved without additional input current controller. So the overall system shows a simple structure. The operational modes are analysed in depth, and then it was verified through the experimental results using a 150 [W] prototype equipped with digital signal processor TMS320F241.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.57-61
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• 2002

This paper presents a current-source-inverter based on a buck-boost configuration and its application for residential photovoltaic system. The proposed circuit has five switches. Among them, only one switch acts as chopping, and the other determine the polarity of output; therefore, it can reduce the switching loss. Because the input inductor current is operated on the discontinuous conduction mode, high power factor can be achieved without additional input current controller. So the overall system shows a simple structure. The operational modes are analysed in depth, and then it was verified through the experimental results using a 150 W prototype.

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.67-75
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• 2011

The development of electric vehicle power electronics system control, composed of DC-AC inverters and DC-DC converters, attract much research interest in the modern industry. A DC-AC inverter supplies the high-power motor torques of the propulsion system and utility loads of electric vehicles, whereas a DC-DC converter supplies the conventional low-power and low-voltage loads. However, the need for high-power bidirectional DC-DC converters in future electric vehicles has led to the development of many new topologies of DC-DC converters. The nonlinear control of power converters is an active research area in the field of power electronics. This paper focuses on the use of the fuzzy sliding mode strategy as a control strategy for buck-boost DC-DC converter power supplies in electric vehicles. The proposed fuzzy controller specifies changes in control signals based on the surface and knowledge on surface changes to satisfy the sliding mode stability and attraction conditions. The performance of the proposed fuzzy sliding controller is compared to that of the classical sliding mode controller. The satisfactory simulation results show the efficiency of the proposed control law, which reduces the chattering phenomenon. Moreover, the obtained results prove the robustness of the proposed control law against variations in load resistance and input voltage in the studied converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.4
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• pp.305-311
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• 2013

This paper proposes a performance improvement of existing single-phase current-fed qZ-Source inverter. Voltage gain of the traditional voltage-fed full-bridge inverter and single-phase current-fed qZ-source inverter is only equal to or smaller than input voltage. The proposed inverter can obtain twice higher voltage gain than the single-phase current-fed qZ-Source inverter by adding an extra switch and a capacitor in the circuit. In addition, the proposed inverter shares the common ground between dc input and ac output voltage. Therefore, the proposed inverter can eliminate the possible ground leakage current problem when it is used for grid-tied photovoltaic inverter system. A 120 W prototype inverter is built and tested to verify performances of the proposed inverter.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.387-389
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• 2006

The LCD TV has many variable functions for consumer. Low temperature driving below minus 20 degree is also one of key functions. Since LCD is not self-luminance device, it is needed backlight system. Recently EEFL(External Electrode Fluorescent Lamp) widely substitutes for CCFL(Cold Cathode Fluorescent Lamp). It is more cheaper, higher efficiency, and easy to drive parallel connection compared to CCFL. In this paper, several conditions for low temperature driving of EEFL are investigated and a new boost-half bridge inverter for low temperature driving is proposed. Mode analysis is described and experimental results is represented to verify validity of the proposed inverter.

• Journal of Electrical Engineering and Technology
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• v.11 no.5
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• pp.1274-1281
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• 2016

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.5
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• pp.437-442
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• 2002

This paper presents a current-source-inverter based on a buck-boost configuration md its application for residential photovoltaic system. The proposed circuit has five switches. Among them, only one switch acts as chopping, and the other determine the polarity of output; therefore, it can reduce the switching loss. Because the input inductor current is operated on the discontinuous conduction mode, high power factor can be achieved without additional input current controller. So the overall system shows a simple structure. The operational modes are analysed in depth, and then it was verified through the experimental results using a 150[W] prototype equipped with digital signal processor TMS320F241.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.11
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• pp.635-644
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• 2002

Many generating units can be in parallel connection to one battery and inverter. However, one of the biggest problems we encountered is that wind speed is fluctuated sharply in accordance with the unstable weather conditions. To solve this problem, we need energy storage equipment such as storage lead-acid battery. We design a system and analyze its modeling so that it supplies a stable power to the load through DC-AC inverter part. In this paper, we applied dual step-up/down buck-boost converter and dual high-frequency half-bridge converter to the proposed system. These converters are used to store energy in the battery regardless of the change of the wind speed. The operation process of two proposed types of converters for high-power battery charging is discussed along with simulation and experimental result. We design a charging circuit which is applicable in the actual wind power generation system for 30kw and confirm the circuit's validity.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.453-454
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• 2011

본 논문에서는 벅-부스트와 포워드 컨버터의 기능을 갖는 컨버터를 제안한다. 제안하는 컨버터는 Cascaded H-bridge 멀티레벨인버터와 같이 다수의 독립된 전원을 요구하는 회로 구조를 단일 입력 전원단으로 구성할 수 있는 특징을 가진다. 벅-부스트 컨버터의 입력 인덕터는 변압기로 대체되며 컨버터 스위치의 ON 동작시 포워드 동작에 의해 변압기 2차측으로 전력전달이 이루어지며, 스위치 OFF시 변압기 1차측 자화인덕턴스에 저장된 에너지가 비절연된 벅-부스트 컨버터의 출력 커패시터로 전달된다. 제안된 컨버터의 동작 모드에 따른 이론적 분석을 시행하고 시뮬레이션을 통해 타당성을 검증한다.