• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.244-246
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• 2008

본 논문에서는 LCD TV의 인치에 따라 다르게 적용되는 기존의 전원 구동 분리형 시스템과 전원 구동 IP 시스템을 검토하여, 두 시스템의 장점만을 모아 LCD TV 전원 시스템의 표준화가 가능한 새로운 방식의 구동 전원 통합 시스템을 제안한다. 제안 시스템은 가격 및 효율이 우수한 2단 구성으로 이루어져 있고, 안전규격을 만족하기 위하여 EMI측면에 유리한 1:1 Trans.를 사용하였다. 인버터 부의 최적 동작을 위해 인버터 구동신호의 주파수와 시비율을 고정하고 펄스 개수를 제어하는 Pulse Count Modulation(PCM)방식을 채용 하였다. 제안 시스템의 인버터단은 전 부하 범위에서 영전압 스위칭이 가능하여 스위치의 발열이 우수하고, 별도의 전류 평형 Trans.가 필요치 않으므로 Balance Coil의 삭제가 가능하다. 이로 인해 신뢰성이 높은 제품 구성이 가능하고, PCB Size 축소 및 제품 제작 단가가 낮아지는 장점을 갖는다. 최종적으로 제안 시스템을 기존 시스템과 비교 및 실험적 검증을 통하여 제안 시스템의 그 우수성을 확인한다.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2701-2703
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• 1999

A new mode of parallel operation of a modular 3-phase AC-DC Flyback converter for high power factor correction along with tight regulation is presented in this thesis. The converter offers input/output transformer isolation for safety, a unity input power factor for minimum reactive power, high efficiency and high power density for minimum weight and volume. Compared with previously developed 3-phase two-stage power converter, the advantage of the proposed converter does not require expensive high voltage and high current devices that are normally needed in popular boost type 3-phase converter. In this paper, a detailed small signal analysis of the modular 3-phase AC-DC flyback converter is provided for control purposes and also experimental results are included to confirm the validity of the analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.86-92
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• 2009

This paper presents development of 6kw ZVS(Zero Voltage Switching) boost converter by 4-parallel operation. To realize a high capacity converter with 6 kw, 4-parallel operation of 1.5kW unit module is proposed in this paper. To meet high ratio input to output voltage, isolated type booster converter is designed. To achieve ZVS operation of 4-switches of full bridge and protect a voltage overshoot caused by switch turn-off, simple active-clamp circuit is applied to the primary side. For parallel operation of 4-modules, master-slave control method is proposed to achieve input current sharing of 4-unit converter modules accurately. For performance tests, simulation is carried out. Also, load and experimental tests of the developed booster converter, 230Vdc/6kW, are carried out under various conditions. For field tests, the developed converter is applied for boosting a battery power to high DC_link voltage for a VSI inverter which starts a micro-turbine(MT) installed in vehicle and it's performance is verified through high speed motoring a MT up to tens of thousands of rpm.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.194-196
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• 2002

액정표시장치(LCD; Liquid Crystal Display)는 표현된 정보를 가시화하기 위해 램프의 백라이트가 필수적인데 대부분 부피가 작고 효율과 휘도특성이 좋은 냉음극 방전램프가 사용된다. 램프는 고압으로 구동되며 높은 전압을 얻기 위해 일반적으로 권선 변압기를 사용한다. 그러나 권선 변압기의 경우 자체의 철심이나 권선의 손실로 인하여 출력 효율의 한계가 있으며, 고압을 위해 감긴 코일은 부피를 크게 하며 무겁게 만든다 이를 해결하기 위해 변압기 자체 손실을 줄이고 소형화가 가능하며 높은 승압비을 가진 PAN-PZT계의 적층형 압전 변압기를 제작하였다. 또한 회로의 손실을 줄이기 위한 영전압 스위칭(ZVS; Zero Voltage Switching)과 그리고 LCD패널과 인버터의 불필요한 간섭현상(EMI; Electro-Magnetic Interference)을 줄일 수 있으며 소형화가 가능한 하프 브리지형 압전 인버터를 설계하였다.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2148-2150
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• 1998

This paper proposes a constant frequency controlled zero voltage switching method that can reduce switching losses caused by emf on inductance in DC motor. The zero voltage switching method is used more than a zero current switching method because of reducing switching losses by capacitance of depletion region of MOSFET. To simplify the controller circuit, we propose constant frequency controlled zero voltage switching method in the paper. The control method is more stable than a variable frequency control method because it can optimize bandwidth of a closed-loop and reactances. Therefore, we construct a constant frequency controlled zero voltage switching converter and improve zero switching losses in high switching frequency. In the process, we can control low-losses in full range on variable voltage and load. We simulate the proposed converter with P-SPICE and compare results obtained through the experiment.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.6
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• pp.432-440
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• 2010

In this paper, a LC series resonant boost converter using a single switch is proposed. The proposed topology contains additional passive elements in the conventional boost converter and performs Zero Voltage Switching(ZVS) without an additional auxiliary switch when a main switch turned on and off. The switch off time of the proposed system determined by LC series resonance, thus a on-time variable Pulse Frequency Modulation(PFM) method is adapted to control output voltage in the proposed converter. Operational modes of the proposed topology are divided with respected to the current conduction paths and then through the theoretical analysis and experimental results, operational modes and characteristics of the proposed converter are verified.

• 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.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.6
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• pp.598-609
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• 2005

Conventional phase shift full bridge (PSFB) converter has serious voltage oscillation problem across the secondary rectifier diodes, which would require the dissipate snubber circuit, thus degrades the overall efficiency. To overcome this problem a new simple voltage oscillation reduction technique (VORT) which effectively reduce the voltage oscillation of the secondary rectifier diodes for phase shift full bridge converter is proposed. Therefore, no dissipate snubber for rectifier diodes is needed. In addition, since it has wide zero voltage switching (ZVS) range, high efficiency can be achieved. Operational principle, analysis of voltage oscillation, and design consideration are presented compare with that of the conventional PSFB converter. To confirm the validity of the proposed VORT, experimental results from a 420W prototype are presented.

• 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.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.286-291
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• 2015

LLC resonant converter is used to control laser output power in Nd:YAG laser. Zero voltage switching (ZVS) is implemented to minimize the switching loss which is adopting the LLC resonant converter. In the spot welding processing of metal thin films, the processing quality is decided by the laser beam output energy of single pulse. We decide to the 50 [J] as the single pulse laser beam energy. Laser output power is investigated and experimented by changing the output current. That current is controled by the charging voltage of capacitor. From those results, we obtained the maximum laser output of 58.2 [J] and the conversion efficiency of 2.52% at the discharge voltage of 620V and the discharge current of 861 [A] and the pulse repetition rate of 1 [Hz] at the charging capacitor of 12,000 [${\mu}F$].