• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1380-1382
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• 2005

The multi-resonant converter minimizes a parasitic oscillation by using the resonant tank circuit absorbed parasitic reactance existing in a converter circuit. So it is possible that the converter operated at a high frequency has a high efficiency because the losses are reduced. However, the resonant voltage stress across a switch is four or five times a input voltage. This high voltage stress increases the conduction loss. In this paper, we proposed the AT flyback multi-resonant converter. The proposed converter can reduce the voltage stress to two or three times by using two series input capacitors. The operational principle of the proposed converter was verified through the experimental converter.

• Journal of Power Electronics
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• v.16 no.2
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• pp.786-797
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• 2016

This paper describes the design and development of a novel semiconductor-based solid-state switch for damped oscillating voltage test system. The proposed switch is configured as two identical series-connected switch stacks, each of which comprising 10 series-connected IGBT function units. Each unit consists of one IGBT, a gate driver, and an auxiliary voltage sharing circuit. A single switch stack can block 20 kV-rated high voltage, and two stacks in series are proven applicable to 30 kV-rated high voltage. The turn-on speed of the switch is approximately 250 ns. A flyback topology-based power supply system with a front-end power factor correction is built for the drive circuit by loosely inductively coupling each unit with a ferrite core to the primary side of a power generator to obtain the advantages of galvanic isolation and compact size. After the simulation, measurement, and estimation of the parasitic effect on the gate driver, a prototype is assembled and tested under different operating regimes. Experimental results are presented to demonstrate the performance of the developed prototype.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.4
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• pp.171-178
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• 2005

The proposed dual-output DC-DC converter that bases on flyback converter can obtain two output voltage with non-isolated main-output and isolated sub-output at the same time using single-winding high frequency transformer. It can solve problems in multi-winding converter that use one main-switch, and also control quality of isolated sub-output voltage can be improved by additional sub-switch to the second. For analysis and design of the proposed converter system, converters are classified as operation mode from switching state and are become modeling by applying state space averaging method. Steady-state characteristics and dynamic characteristics are analyzed by DC component and perturbation component from state space averaging model. From experiment converter, validity of analysis and design for the propose converter system is confirm.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.363-365
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• 2006

소비자의 요구와 기술력의 발달로 PDP시장은 42인치와 60인치등 대형PDP가 주류를 이루고 있으며 대형화에 따라서 PDP전원의 소모전력 또한 $400W{\sim}600W$ 까지 증가 하고 있다. 기존 소용량 PDP전원으로 사용되던 Flyback의 경우 소모 전력이 증가함에 따라 대형PDP에 적용하기에는 소자 내압 및 시스템 효율 측면에서 다소 무리가 있다. 따라서 대형PDP의 전원을 위해서 새로운 2 Switch 3 Diode를 채용한 고효율 DCR (Diode Clamping Rectifier) Flyback Converter를 제안하였으며 이를 42인치 PDP에 적용하여 회로의 타당성 및 우수성을 검증하였다.

• Journal of Electrical Engineering and Technology
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• v.4 no.1
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• pp.79-86
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• 2009

This paper presents a flyback technology in power conversion aimed at increasing efficiency and power density, reducing cost and using minimum components in AC-DC conversion. The proposed converter provides these features for square waveforms and constant frequency PWM. It is designed to operate in a wide input voltage range of 75-265VAC RMS with two output voltages of 5V and 20V respectively and full load output power of 5W. The proposed converter is suitable for high efficiency and high power density application such as LCDs, TV power modules, AC adapters, motor control, appliance control, telecom and networking products.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.274-276
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• 2008

This paper proposes an individual charge equalization converter using selective two current paths for series connected lithium-ion battery strings. In the proposed equalizer, a central equalization converter acting as a controllable current source is sequentially connected in parallel with individual batteries through an array of cell selection switches. A flyback converter with a modified rectifier realizes a controllable current source. A central equalization converter is shared by every battery cells through the cell selection switch, instead of a dedicated charge equalizer for each cell. With this configuration, although the proposed equalizer has one dc-dc converter, individual charge equalization can be effectively achieved for the each cell in the strings. Furthermore, since the proposed equalizer would not allocate the separated dc-dc converter to each cell, such that the implementation of great size reduction and low cost can be allowed. In this paper, an optimal power rating design guide is also employed to obtain a minimal balancing size while satisfying equalization requirements. A prototype for eight lithium-ion battery cells is optimally designed and implemented. Experimental results verify that the proposed equalization method has good cell balancing performance showing small size, and low cost.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.85-89
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• 2003

Many single-stage PFC(power-facto.-correction) ACHC converters suffer from the high link voltage at high input voltage and light load condition. In this paper, to suppress the link voltage, a novel high power factor high efficiency PFC AC/DC converter is proposed using the single controller which generates two gate signals so that one of them is used far gate signal of the flyback DC/DC converter switch and the other is applied to the Boost PFC stage. A 130w prototype for LCD monitor adapter with universal input $(90-265V_{rms})$ and 19.5V 6.7A output is implemented to verify the operational principles and performances. The experimental results show that the maximum link voltage stress is about 450V at 270Vac input voltage. Moreover, efficiency and power factor are over $84\%$ and 0.95, respectively, under the full load condition.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.551-555
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• 2004

The two-transformer full bridge (TTFB) PWM converter has two transformers which act as the output inductor as well as the main transformer, i.e. as the forward and the flyback transformer. Although the doubled leakage inductor of the TTFB makes it easier to achieve the zero-voltage switching (ZVS) of the lagging leg switch along the wide load range, it instigates a serious voltage ringing in the secondary rectifier diodes, which would require the dissipative snubber circuit, cause the serious power dissipation, and increase the voltage stress across those diodes. To overcome these problems, a, new lossless diode-clamp rectifier (LDCR) is employed as the output rectifier, which helps the voltage across rectifier diodes to be clamped on a half the output voltage $(V_o/2)$ or the output voltage $(V_o)$. Therefore, no dissipative snubber for rectifier diodes is needed and a high efficiency as well as low noise output voltage can be realized. The operations, analysis and design consideration of proposed converter are presented in this paper. To verify the validity of the proposed converter, experimental results from a 425W, 385-170Vdc prototype for the plasma display panel (PDP) sustaining power module (PSPM) are presented.