• Journal of Power Electronics
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• v.17 no.1
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• pp.20-30
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• 2017

A novel zero-voltage-switching (ZVS) push-pull forward converter with a parallel resonant network is presented in this paper. The novel topology can provide a releasing loop for the energy storage in a leakage inductor for the duration of the power switching by the resonant capacitors paralleled with the primary windings of the transformer. Then the transformer leakage inductor is utilized to be resonant with the parallel capacitor, and the ZVS operation is achieved. This converter exhibits many advantages such as lower duty-cycle losses, limited peak voltage across the rectifier diodes and a higher efficiency. Furthermore, the operating principles and key problems of the converter design are analyzed in detail, and the ZVS conditions are derived. A 500W experimental converter prototype has been built to verify the effectiveness of the proposed converter, and its maximum efficiency reaches 94.8%.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.4
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• pp.37-44
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• 2001

The experimental results and application potentials of a ZVS Forward DC-DC converter based coreless PCB transformer and coreless inductor are presented. The experimental converter, that has a maximum power of 12W, maximum switching frequency of 2.2MHz and nominal input voltage of 24V, has been successfully implemented. The coreless PCB transformer and inductor are found to have many favorable characteristics to high frequency operations due to the absence of a core loss. A power conversion efficiency of the experimental converter was measured at 70${\sim}$80%, and the output was regulated at 12V within 0.7% tolerance.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.67 no.2
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• pp.82-89
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• 2018

This paper presents a novel prototype of dual mode control based phase shift ZVS PWM high frequency load resonant inverter with lossless snubber capacitors in addition to a single active auxiliary resonant snubber for electromagnetic induction heating(IH) foam metal based consumer fluid dual packs(DPA) heater. The operating principle in steady state and unique features of this voltage source soft switching high frequency inverter circuit topology are described in this paper. The lossless snubber and auxiliary active resonant snubber assisted constant frequency phase shift ZVS PWM high frequency load resonant inverter employing IGBT power modules actually is capable of achieving zero voltage soft commutation over a widely specified power regulation range from full power to low power. The steady state operating performances of this dual mode phase shift PWM series load resonant high frequency inverter are evaluated and discussed on the basis of simulation and experimental results for induction heated foam metal heater which is designed for compact and high efficient moving fluid heating appliance in the consumer pipeline systems.

• Journal of Power Electronics
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• v.16 no.2
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• pp.425-435
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• 2016

This paper presents a comprehensive theoretical analysis and an accurate calculation method of the dead-time required to achieve zero-voltage-switching (ZVS) in a battery charger with the phase-shifted full-bridge (PSFB) topology. Compared to previous studies, this is the first time that the effects of nonlinear output filter inductance, varied Miller Plateau length, and blocking capacitors have been considered. It has been found that the output filter inductance and the Miller Plateau have a significant influence on the dead-time for ZVS when the load current varies a lot in battery charger applications. In addition, the blocking capacitor, which is widely used to prevent saturation, reduces the circulating current and consequently affects the setting of the dead-time. In consideration of these effects, accurate analytical equations of the dead-time range for ZVS are deduced. Experimental results from a 1.5kW PSFB battery charger prototype shows that, with the proposed analysis, an optimal dead-time can be selected to meet the specific requirements of a system while achieving ZVS over wide load range.

• Journal of Power Electronics
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• v.12 no.2
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• pp.249-257
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• 2012

An interleaved PWM converter is proposed to implement the features of zero voltage switching (ZVS), load current sharing and ripple current reduction. The proposed converter includes two ZVS converters with a common clamp capacitor. With the shared capacitor, the charge balance of the two interleaved parts is automatically regulated under input voltage and load variations. The active-clamping circuit is used to realize the ZVS turn-on so that the switching losses on the power switches are reduced. The ZVS turn-on of all of the switching devices is achieved during the transition interval. The interleaved pulse-width modulation (PWM) operation will reduce the ripple current and the size of the input and output capacitors. The current double rectifier (CDR) is adopted in the secondary side to reduce output ripple current so that the sizes of the output chokes and capacitor are reduced. The circuit configuration, operation principles and design considerations are presented. Finally experimental results based on a 408W (24V/17A) prototype are provided to verify the effectiveness of the proposed converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.64-73
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• 2001

This paper presents a Zero Voltage and Zero Current Switching (ZVZCS) 3-Level DC/DC converter. This converter overcomes the drawbacks presented by the conventional Zero Voltage Switching(ZVS) 3-Level converter, such as high circulating energy, severe parastic ringing on the rectifier diodes, and limited ZVS load range for the inner switches. The converter presented in this paper uses a phase shift control with a flying capacitor in the primary side to achieve ZVS for the outer switches. Additionally, the converter uses an energy recovery snubber to reset the primary current during the free-wheeling stage to achieve ZCS for the inner switches. The proposed converters are analyzed and verified on 6kW, 39kHz experimental prototype.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.2
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• pp.177-185
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• 2005

A new high efficiency DC/DC converter is proposed, which is derived from the conventional asymmetric half-bridge converter. Because the proposed converter has better ZVS condition compared with the conventional asymmetric half-bridge converter, it shows a high efficiency along the wide load range. In this paper, the basic operations of the proposed converter is analyzed and compared with that of the conventional half-bridge converter, and the excellent performance of the proposed converter is verified by the experimental results with the 425W, 385-170Vdc prototype of the power supply for PDP (Plasma Display Panel) Sustain Driver of PDP TV.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.128-129
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• 2017

기존 Induction Heating용 인버터의 경우, 일반적인 Half-Bridge 인버터를 사용하여 낮은 효율이 발생하기 때문에 고효율 구동이 어렵고, Single Switch 인버터를 사용할 경우 높은 전압 스트레스로 인해 고효율 및 고출력 IH 인버터 구동이 어려운 문제점이 있다. 본 논문은 Induction Heating용 인버터의 원가를 감소시키고 고효율/고출력을 낼 수 있는 스위치 내압 저감용 ZVS Signle Switch 인버터를 제안한다. 기존의 IH 구동용 인버터를 사용할 경우에는 낮은 효율 및 높은 스위치의 전압 스트레스 때문에, 회로의 전체적인 부피가 커지고 제작단가가 증가하는 단점이 있다. 반면 제안된 회로는 IH 구동용 스위치 내압 저감이 가능한 ZVS Single Switch 인버터로써, 단일 스위치 회로 구현과 영전압 스위칭을 통해 높은 효율로 인버터 구동이 가능하고, 스위치 내압을 감소하였기 때문에 회로의 부피 및 원가를 감소시킬 수 있는 장점을 갖는다. 본 논문에서는 제안된 회로의 이론적이 특성을 분석하고 모의실험을 통해 확인하였으며, 2.6kW급 IH 구동 인버터 회로에 적용하여 실험을 통해 우수성을 검증하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.4
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• pp.19-27
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• 1997

This paper has described about principle and form of proposed circuit made use of soft switching technology ZVS(Zero Voltage Switching) to reduce turn on and off loss at switching. Also, the analysis of the proposed circuit has described generally by using normalized parameter and operating characteristics have been evaluated as to switching frequency and parameters. Based on the characteristics value, a method of the circuit design is proposed. In addition, this paper proves the propriety of theoretical analysis in terms of the experimental waveforms. In the future, this proposed inverter shows that it can be practically used as power source system for induction cooker etc.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.535-538
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• 1994

In this paper, an isolated ZVS-PWM boost converter is proposed for single stage line conversion. For power factor correction, we used the half bridge topology at the primary side of isolation transformer permitting switching devices to operate under ZVS by using circuit parastics and operating at a fixed duty ratio near 50%. Thus the relatively continuous input current distortion and small size input filter are also achievable. The ZVS-PWM boost operation of the proposed converter can be achieved by using the boost inductor $L_f$, main switch $Q_3$, and simple auxiliary circuit at the secondary side of isolation transformer. The secondary side circuit differ from a conventional PWM boost converter by introduction a simple auxiliary circuit. The auxiliary circuit is actived only during a short switching transition time to create the ZVS condition for the main switch as that of the ZVT-PWM boost converter. With a single stage, it is possible to achieve a sinusoidal line current at unity power factor as well as the isolated 48V DC output. Comparing to the two stage schemes, overall effiency of the proposed converter is highly improved due to the effective ZVS of all devices as well as single stage power conversion. Thus, it can be operated at high switching frequency allowing use of small size input filter. Minimum voltage and current stress make it high power application possible.