• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1303-1305
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• 2000

A zero voltage and zero current switching(ZVZCS) fullbridge (FB) PWM converter with secondary auxiliary circuit is proposed. Based on the ZVZCS technique, the ZCS of the lagging-leg switch and ZVS of the leading-leg switch are implemented. And the each secondary side voltage overshoot is decreased by additional secondary auxiliary circuit in this paper. The illustration of its operation principle and the simulation result are presented here.

• Journal of Power Electronics
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• v.7 no.2
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• pp.118-123
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• 2007

This paper presents a new ZCS-PWM high frequency inverter. Zero current switching operation is achieved in the whole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor. Dual duty cycle control scheme is used to provide a wide range of high frequency AC output power regulation that is important in many high frequency inverter applications. It found that a complete soft switching operation can be achieved even for low power setting ranges by introducing high-frequency dual duty cycle control scheme. The proposed high frequency inverter is more suitable for consumer induction heating(IH) applications. The operation and control principle of the proposed high frequency inverter are described and verified through simulated results.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1006-1007
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• 2006

An active-clamp current-fed push-pull converter for the step-up application is proposed. The proposed converter is composed of active-clamp circuits and a voltage doubler rectifier. Thus, the voltage stress of the main switches is reduced and the output diodes are clamped to output voltage. Moreover, the output diodes can achieve zero current switching (ZCS) by the series resonance between resonant capacitors and leakage inductances. The prototype is designed for 350V/1.5kW with input voltage range $30{\sim}60V$. The theoretical analysis and experimental results are presented.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.1 s.307
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• pp.45-52
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• 2006

In this paper, authors propose a step-up converter of pulse width modulation (PWM) and power factor correction (PFC) by using a novel loss-less snubber. The proposed converter for a discontinuous conduction mode (DCM) eliminates the complicated circuit control requirement and reduces the size of components. The input current waveform in the proposed converter is got to be a sinusoidal form of discontinuous pulse in proportion to magnitude of ac input voltage under the constant duty cycle switching. Thereupon, the input power factor is nearly unity and the control method is simple. In the general DCM converters, the switching devices are fumed-on with the zero current switching (ZCS), and the switching devices must be switched-off at a maximum reactor current. To achieve a soft switching (ZCS and ZVS) of the switching turn-off, the proposed converter is constructed by using a new loss-less snubber which is operated with a partial resonant circuit. The result is that the switching loss is very low and the efficiency of converter is high. Some simulative results on computer and experimental results are included to confirm the validity of the analytical results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.3
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• pp.40-51
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• 2008

This research presents a new active auxiliary resonant snubber with for induction heating PWM high frequency inverter solving the problem of induction heating PWM high frequency inverter circuit which is using widely in the practical application of an induction heating apparatus, the soft switching operation and power control are impossible when the lowest power supply in the active auxiliary resonant snubber with for induction heating PWM high frequency inverter. The inverter circuit which is attempted by the on-off operation of a switch has the effect of reducing the power loss due to soft switching and high frequency switching. This confirms that power regulation is possible on a continuous basis from 0.25[kW] to 2.84[kW] where the duty factor(D) changes from 0.08 to 0.3 under zero current switching which operates by an asymmetrical pulse width modulating control. The power conversion efficiency is 95[%]. Due to these results, the active auxiliary resonant snubber for an induction heating PWM high frequency inverter is considered effective as a source of induction heating.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.305-308
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• 2000

A technique to suppress the low frequency ripple voltage of the DC output in three phase buck diode rectifiers is presented in this paper. The proposed pulse frequency modulation methods and duty ratio modulation methods are employed to regulate the output voltage of the buck diode rectifiers and guarantee zero-current -switching(ZCS) of the switch over the wide load range The proposed control methods used in this paper provide generally good performance such as low THD of the input line current and unity power factor. IN addition control methods can be effectively used to suppress the low frequency ripple voltage appeared in the dc output voltage. The harmonic injection technique illustrates its validity and effectiveness through the simulations.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.347-348
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• 2014

본 논문에서는 3D TV를 위한 다채널 전류평형 단일스위치 LED 구동회로를 제안한다. 제안된 구동회로는 각각의 LED 채널의 정전류 제어를 위해 별도의 전력단을 사용하는 대신에 2차 측에 단 1개의 switch를 추가하여 하나의 채널 전류를 정전류 제어하고 나머지 다른 채널의 전류를 캐패시터의 성질을 이용한 회로를 사용함으로써 모든 채널 전류의 정전류 제어 및 전류평형이 가능한 회로이다. 추가된 switch는 ZCS(Zero Current Switching) 동작하므로 스위칭 손실을 최소화하여 고효율화 시킬 수 있다. 또한, 여러 LED 채널의 정전류 제어를 별도의 LED Driver단을 사용하지 않고 캐패시터의 성질을 이용하여 구현하기 때문에 소형화 및 저가격화가 가능하다. 최종적으로 제안된 회로의 우수성과 이론적 분석의 타당성 검증을 위해 46" LED 3D-TV 구동회로를 위한 시작품을 제작하여 고찰된 실험 결과를 제시한다.

• Journal of Magnetics
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• v.16 no.1
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• pp.51-57
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• 2011

A power supply for magnetic-stimulation devices was designed via a control algorithm that involved a start current application based on a resonant converter. In this study, a new power supply for magnetic-stimulation devices was designed by controlling the pulse repetition frequency and pulse width. The power density could be controlled using the start-current-compensation and ZCS (zero-current switching) resonant converter. The results revealed a high-repetition-frequency, high-power magnetic-stimulation device. It was found that the stimulation coil current pulse width and that pulse repetition frequency could be controlled within the range of 200-450 ${\mu}S$ and 200-900 pps, respectively. The magnetic-stimulation device in this study consisted of a stimulation coil device and a power supply system. The maximum power of the stimulation coil from one discharge was 130 W, which was increased to 260 W using an additional reciprocating discharge. The output voltage was kept stable in a sinusoidal waveform regardless of the load fluctuations by forming voltage and current control using a deadbeat controller without increasing the current rating at the starting time. This paper describes this magnetic-stimulation device to which the start current was applied.

• Journal of Power Electronics
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• v.15 no.3
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• pp.587-601
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• 2015

A high step-up dc-dc converter is proposed for photovoltaic power systems in this paper. The proposed converter consists of an input current doubler, a symmetrical switched-capacitor doubler and an active-clamp circuit. The input current doubler minimizes the input current ripple. The symmetrical switched-capacitor doubler is composed of two symmetrical quasi-resonant switched-capacitor circuits, which share the leakage inductance of the transformer as a resonant inductor. The rectifier diodes (switched-capacitor circuit) are turned off at the zero current switching (ZCS) condition, so that the reverse-recovery problem of the diodes is removed. In addition, the symmetrical structure results in an output voltage ripple reduction because the voltage ripples of the charge/pump capacitors cancel each other out. Meanwhile, the voltage stress of the rectifier diodes is clamped at half of the output voltage. In addition, the active-clamp circuit clamps the voltage surges of the switches and recycles the energy of the transformer leakage inductance. Furthermore, pulse-width modulation plus phase angle shift (PPAS) is employed to control the output voltage. The operation principle of the converter is analyzed and experimental results obtained from a 400W prototype are presented to validate the performance of the proposed converter.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.1030-1035
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• 1998

This paper describes a new dc-ac inverter system, which for achieving sinusoidal ac waveform make use of parallel loaded frequency resonant inverter consisting of full bridge. Each one of the pair of switches in the inverter is driven to synchronous output frequency and the other is driven to PWM signal with resonant frequency proportional to magnitude of sine wave. Since current through switches is always zero at its turn-on in proposed inverter, low stress and low switching loss is achieved. The theoretical analysis is proved through the experimental test.