• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권9호
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• pp.431-436
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• 2005

This paper studies a novel boost DC-DC converter operated high efficiency for discontinuous current mode (DCM) control. The converter worked in DCM eliminates the complicated circuit control requirement, reduces a number of components, and reduces the used reactive components size. In the general DCM converter, the switching devices are turned-on the zero current switching (ZCS), and the switching devices must be switched-off at a maximum reactor current. To achieve the zero voltage switching (ZVS) at the switching turn-off, the proposed converter is constructed by using a new loss-less snubber circuit. Soft-switched operation of the proposed boost converter is verified by digital simulation and experimental results. A new boost converter achieves the soft-switching for all switching devices without increasing their voltage and current stresses. The result is that the switching loss is very low and the efficiency of boost DC-DC converter is high.

• Journal of Electrical Engineering and Technology
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• 제11권6호
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• pp.1634-1644
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• 2016

In this paper, a current-fed two-inductor bi-directional DC/DC converter using resonance (CF-TIBCR) and its design method are proposed. The CF-TIBCR has characteristics of low current ripple and a high current rating because of two separated inductors. Also, it achieves zero voltage switching for all switches and zero current switching for switches of a low voltage stage by using the resonant tank. Besides, a voltage spike problem in conventional current-fed converters is solved without the need for an additional snubber or clamping circuits. As a result, the CF-TIBCR features high step-up and high efficiency. Since the proposed converter has difficulty achieving the soft-switching condition when the converter requires the low voltage transfer ratio, a method that varies the number of resonant cycles is adopted to extend the output voltage range with satisfying the soft-switching condition. The principles of the operation characteristics are presented with a theoretical analysis, and the proposed converter is verified through results of an experiment using a laboratory prototype.

• Journal of Power Electronics
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• 제16권6호
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• pp.1991-2004
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• 2016

An LC filter is required to reduce the output current ripple in the auxiliary resonant snubber inverter (ARSI) for high-performance applications. However, if the traditional control method is used in the ARSI with LC filter, then unnecessary current flows in the auxiliary circuit. In addressing this problem, a novel load-adaptive control that fully uses the filter inductor current ripple to realize the soft-switching of the main switches is proposed. Compared with the traditional control implemented in the ARSI with LC filter, the proposed control can reduce the required auxiliary current, contributing to higher efficiency and DC-link voltage utilization. In this study, the detailed circuit operation in the light load mode (LLM) and the heavy load mode (HLM) considering the inductor current ripple is described. The characteristics of the improved ARSI are expressed mathematically. A prototype with 200 kHz switching frequency, 80 V DC voltage, and 8 A maximum output current was developed to verify the effectiveness of the improved ARSI. The proposed ARSI was found to successfully operate in the LLM and HLM, achieving zero-voltage switching (ZVS) of the main switches and zero-current switching (ZCS) of the auxiliary switches from zero load to full load. The DC-link voltage utilization of the proposed control is 0.758, which is 0.022 higher than that of the traditional control. The peak efficiency is 91.75% at 8 A output current for the proposed control, higher than 89.73% for the traditional control. Meanwhile, the carrier harmonics is reduced from -44 dB to -66 dB through the addition of the LC filter.

• 조명전기설비학회논문지
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• 제21권4호
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• pp.19-27
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• 2007

This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit incorporating boost H-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switch mode equivalent circuits and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft-switching(ZVS) operation ranges, and the power dissipation as compared with those of the conventional type high frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation(PWM) and pulse density modulation(PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.

• Journal of Power Electronics
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• 제11권1호
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• pp.10-15
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• 2011

In this paper, a new soft switching three phase inverter with a quasi-resonant dc-link is presented. The proposed inverter has a dc-link switch and an auxiliary switch. The inverter switches are turned on and off under zero voltage switching condition and all auxiliary circuit switches and diodes are also soft switched. The control utilizes PWM and the auxiliary switch does not require an isolated gate drive circuit. In this paper, the operation analysis and design considerations of the proposed soft switching inverter are discussed. The presented experimental results of a realized prototype confirm the theoretical analysis.

• Journal of Power Electronics
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• 제11권6호
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• pp.779-786
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• 2011

This paper presents a soft switching converter to achieve the functions of zero voltage switching (ZVS) turn-on for the power switches and dc voltage step-up. Two circuit modules are connected in parallel in order to achieve load current sharing and to reduce the size of the transformer core. An active snubber is connected between two transformers in order to absorb the energy stored in the leakage and magnetizing inductances and to limit the voltage stresses across the switches. During the commutation stage of the two complementary switches, the output capacitance of the two switches and the leakage inductance of the transformers are resonant. Thus, the power switches can be turned on under ZVS. No output filter inductor is used in the proposed converter and the voltage stresses of the output diodes is clamped to the output voltage. The circuit configuration, the operation principles and the design considerations are presented. Finally, laboratory experiments with a 340W prototype, verifying the effectiveness of the proposed converter, are described.

• 전력전자학회논문지
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• 제25권6호
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• pp.484-489
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• 2020

This study proposes a new soft-switching three-level flying capacitor converter with low filter inductance. The proposed converter can achieve zero voltage switching (ZVS) turn-on of all switches by using auxiliary components La and Ca. It can also reduce filter inductance because the applied voltage of the filter inductor is decreased by using the flying capacitor. Furthermore, filter inductance can be reduced because the operating frequency of the filter inductor is doubled by the phase shifting between switches S3 and S4. The operation principle, design of passive components for ZVS turn-on, interleaving effects, and comparison of different topologies are presented. The experimental waveforms of a 1 kW two-phase interleaved converter prototype are provided to verify the validity of the proposed converter.

• 전기학회논문지
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• 제59권3호
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• pp.569-574
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• 2010

The full bridge converter have been used for high power system that is needed to switch the big current. So, EMI and stability problem is occurred. The Soft switching method is the solution to solve the above problem, But implementation of soft switching(ZVS: Zero Voltage Switching) is so complicate and expensive because of the DSP MCU and shift circuit. In this paper, we introduce the technical method for driving circuit of ZVS full bridge converter with 1st order delay circuit and logic elements. The realization of this method is so simple and cheap. The effectiveness of the proposed circuit is verified by experimental results.

• 전자공학회논문지SC
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• 제37권1호
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• pp.56-63
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• 2000

Buck 컨버터는 간단한 회로구조와 뛰어난 안정성으로 인하여 DC-DC 컨버터 중에서 가장 많이 이용되는 Topology이다. 그러나 박막 인버터를 기존의 buck 컨버터에 이용하는 경우 박막 인덕터의 인덕턴스가 기본적으로 작은 값이 되므로 최적의 리플전압을 얻기 위해서는 필요이상으로 주파수를 높일 필요가 있으며 이 경우 스위칭손실에 의한 컨버터의 효율저하를 초래하게 된다. 본 논문에서는 이러한 문제점을 해결하기 위하여 박막 인버터의 낮은 인덕턴스 값을 이용하여 스위치에 있어서 영전압 스위칭동작을 구현함으로써 컨버터의 효율을 상승시킬 수 있는 1W급 ZVS-CV Buck 컨버터를 제안하였으며, 실험과 손실해석을 통하여 박막 인덕터를 이용한 ZVS-CV Buck 컨버터의 정상동작을 확인하였고 기존의 Buck 컨버터 보다 효율이 약 4% 향상됨을 입증하였다.

• 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.