• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.2
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• pp.154-162
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• 2000

A technique to suppress the low frequency ripple voltage of the DC output ${\gamma}$oltage in three-phase buck d diode rectifiers is presented in this paper. The proposed pulse frequency modulation method is employed to r regulate the output voltage of the buck diode rectifiers and guarantee zero-current switching of the switch over the Vvide load range. The pulse frequency control method used in tIns paper shows generally good p performance such as low THD of the input line current and unity power factor. In addition, the pulse f freιluency method can be effectively used to suppress the low frequency voltage ripple appeared in the dc output voltage. The proposed technique illustrates its validity and effectiveness through the respective s simulations and experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.6
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• pp.55-64
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• 2007

This paper represents characteristics and design example of series loaded LCC type high frequency resonant DC-DC converter with variable parallel capacitor in the secondary side of inductive power transformer. In this converter, ZVS(zero voltage switching) technique is applied to reduce turn-off switching losses, and the applied converter used the PFM switching pattern to control output voltage. The operating characteristics of the proposed converter is analyzed using nomalized parameter such as switching frequency and load factor with varing the secondary parallel resonant capacitor. The results of analysis show the operating characteristics and design method of the proposed converter using characteristic values. And the proposed converter can be applied for the contactless power supply with linear transfer system such as dean room facilities of semiconductor and Flat Panel Display.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.6
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• pp.453-460
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• 2008

This paper proposes a new multi-output LLC resonant converter by using single control IC, which has the tight-regulated dual output voltage without additional power devices and controller. The proposed converter has master and slave outputs, of which regulations are achieved by the PWM(pulse width modulation) and PFM(pulse frequency modulation), respectively. Different from the conventional dual-output LLC resonant converter, the proposed converter has no additional post-regulators like a boost converter. Therefore, it features a low cost, small size, and high efficiency. To confirm the validity and prove the superiority of proposed converter, simulated and experimental results on a 50" FHD PDP power set prototype are presented.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.537-538
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• 2008

A step-down DC-DC converter with On-chip Compensation for battery-operated portable electronic devices which are designed in 0.18um CMOS standard process. In an effort to improve low load efficiency, this paper proposes the PFM (Pulse Frequency modulation) voltage mode 1MHz switching frequency step-down DC-DC converter with on-chip compensation. Capacitor multiplier method can minimize error amplifier compensation block size by 20%. It allows the compensation block of DC-DC converter be easily integrated on a chip and occupy less layout area. But capacitor multiplier operation reduces DC-DC converter efficiency. As a result, this converter shows maximum efficiency over 87% for the output voltage of 1.8V (input voltage : 3.3V), maximum load current 500mA, and 0.14% output ripple voltage. The total core chip area is $mm^2$.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.397-399
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• 2008

본 논문은 대용량에 적합한 새로운 DC/DC 컨버터에 관한 것으로써, PFM-SBC(Series-Boost Capacitor) 풀 브리지 컨버터를 제안한다. 제안된 회로는 스위칭 주파수에 따라 직렬 부스트 캐패시터의 전압을 증감하여 출력전압을 제어하는 방식이며, 50% 고정 시비율로 구동하기 때문에 기존 위상천이 풀 브리지 회로에 존재하는 환류 구간이 발생하지 않는다. 또한 넓은 부하 영역에 대해 영전압-스위칭이 보장되므로 효율 및 발열 특성이 우수하며, 출력 인덕터 전류 리플이 작은 장점이 있다. 본 논문에서는 기존 컨버터들의 특성을 분석하고, 제안된 회로의 이론적 해석 및 PSIM 모의실험을 수행하며, 이를 실제로 1.2KW급 서버용 전원장치 프로토 타입 제작을 통하여 제안된 SBC 풀 브리지 컨버터의 타당성을 검증한다.

• Journal of Power Electronics
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• v.16 no.3
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• pp.840-848
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• 2016

A primary-side regulation AC-DC converter operating in the PFM (Pulse Frequency Modulation) mode with a high precision output current is designed, which applies a novel inductance compensation technique to improve the precision of the output current, which reduces the bad impact of the large tolerance of the transformer primary side inductance in the same batch. In this paper, the output current is regulated by the OSC charging current, which is controlled by a CC (constant current) controller. Meanwhile, for different primary inductors, the inductance compensation module adjusts the OSC charging current finely to improve the accuracy of the output current. The operation principle and design of the CC controller and the inductance compensation module are analyzed and illustrated herein. The control chip is implemented based on a TSMC 0.35μm 5V/40V BCD process, and a 12V/1.1A prototype has been built to verify the proposed control method. The deviation of the output current is within ±3% and the variation of the output current is less than 1% when the inductances of the primary windings vary by 10%.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.207-210
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• 2002

This paper describes a design of multiple-mode single-output DC/DC converter which can be used in both up and down conversion. Proposed up/down converter does not produce a negative voltage which is generated in conventional buck-boost type converter. Three types of operation mode(up/down/bypass) are controlled by the input voltage sense and command signals of target output voltage. PFM(pulse frequency modulation) control is adopted and modified for fast tracking and for precise output voltage level with an aid of output voltage sense. Designed DC/DC converter has the performance of less than 5 % ripple and higher than 80 % efficiency. Chip area is 3.50 mm ${\times}$ 2.05 mm with standard 0.35 $\mu\textrm{m}$ CMOS technology.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.7
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• pp.20-28
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• 2009

This paper presents the design of zero current switching ZCS pulse frequency modulation type DC-DC converter for magnetron power supply. A magnetron serving as the microwave source in a microwave oven is driven by a switch mode power supply (SMPS). SMPSs have the advantages of improved efficiency, reduced size and weight, regulation and the ability to operate directly from the converter DC bus. The demands of the load system and the design of the power supply required to produce constant power at 4[kV]. A magnetron power supply requires the ability to limit the load current under short circuit conditions. The current source series resonant converter is a circuit configuration which can achieve this. The main features of the proposed converter are an inherent protection against a short circuit at the output, a high voltage gain and zero current switching over a large range of output power. These characteristics make it a viable choice for the implementation of a high voltage magnetron power supply.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.277-278
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• 2014

본 논문은 저 대기전력의 구현이 가능하며 출력전압을 정확하게 제어할 수 있는 플라이백 컨버터 제어방식을 제안한다. 제안 방식은 모든 절연 형 컨버터에 적용 가능하고, 2차 측에 PFM(Pulse Frequency Modulation) IC를 위치시켜 정확한 출력전압 제어가 가능하다. 또한, 1,2차 측간에 신호 전달을 위하여 기존에 사용되는 TL431과 포토커플러가 아닌 Y-capacitor와 Low-Pass-Filter를 적용하여, 저 대기전력 구현이 가능하다. 제안방식의 타당성을 검증하기 위하여 이론적 해석과 시뮬레이션을 통하여 가능성을 확인하였다.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1416-1418
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• 2005

This paper presents a new hybrid control method of asymmetrical half-bridge converter(AHBC) with low voltage stresses of the diodes and interleaved PFC(power factor correction). The proposed new control scheme can observe variation of secondary diodes voltage stresses by variation of duty ratio and then decide the control portions which are asymmetrical control and PFM(Pulse Frequency Modulation). Therefore, the proposed control scheme has many advantages such as a low rated voltage of the secondary diodes, low conduction loss according to the low voltage drop and wide zvs range by load variation. Through simulation results, the validity of the proposed control scheme is demonstrated.