• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.248-253
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• 2014

Generally, power factor correction (PFC) techniques play an important role in the power supply technology. Many new circuit topologies and control strategies for PFC have been proposed. Among them, the brideless PFC (BPFC) reduces the number of switching devices and the losses and improves the power density as well. Moreover, by implementing the improved topology in the discontinous conduction mode (DCM) it ensures almost unity power factor in a simple and effective manner. In the DCM operation gives additional advantages such as zero-current turn-on in the power switches, zero-current turn-off in the output diode and reduces the complexity of the control circuitry. In this paper, a new control strategy for the BPFC is proposed. Also, the performance of the proposed system is demonstrated through experiments.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.172-174
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• 2007

The AC-DC Adapter has been widely used in Mobile Phones, Note Book PC, LCD monitors, and portable electronic products. Recently, high-power-density Adapter was developed. This adapter increases power factor using a bridge diode rectifier and PFC, however, there are weak points that improving efficiency is limited. In the bridgeless rectifier circuit proposed in this paper, there is no PFC, however, the power factor and efficiency are improved by BCM and ZCS operations.

• Journal of the Semiconductor & Display Technology
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• v.17 no.1
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• pp.21-26
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• 2018

In this paper, a multiple coupling inductor with expandable-integrated magnetic structure was proposed to enable miniaturization of external switched mode power supply (SMPS) for a large display. Inductance formula of the proposed inductor structure was derived through magnetic circuit analysis for a simple inductance designing process. The proposed inductor was applied into a 1kW class interleaved bridgeless power factor correction circuit which requires four inductors, and experimental steady state result of the circuit was compared. According to the experimental result, it was found that the proposed multiple coupling inductor shows the electrical characteristics that can replace the conventional separated inductors and is suitable for miniaturization of the SMPS since the circuit configuration is possible with one shared inductor.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.3
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• pp.223-227
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• 2016

Power supplies make the load compatible with its power source. DC power supplies are extensively used with most electrical and electronic appliances such as computers, television, and audio sets. The presence of non-linear loads results in a low power factor and higher harmonics in the power system. Several techniques for power-factor correction and harmonic reduction have been reported in the literature. This paper proposes a bridgeless boost converter that improves the power factor and reduces the harmonic content in input line currents as compared to full-bridge rectifiers. This bridgeless boost converter eliminates the need of a line-voltage bridge rectifier in conventional boost converter and thereby reduces conduction losses. The effectiveness of the proposed scheme is verified by computer simulations by using the PSIM software.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.3
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• pp.226-232
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• 2005

Recently, many nation have released standard such as IEC 61000-3-2 and IEEE 59, which impose a limit on the harmonic current drawn by equipment connected to AC line in order to prevent the distortion of an AC Line. Therefore, Plasma Display Panel(PDP) which is highlightened in digital display device also has the Power Factor Correction(PFC) circuit to meet the harmonic requirements. In PDP power module, the conventional boost converter is usually used for the PFC circuit. However, it comes serious thermal problem on it's bridge diode due to heat of PDP, and therefore the system stability is not guaranteed. In this paper, the bridgeless boost converter, which is used for PFC circuit of the PDP power module, is designed and verified the possibility of the application In a practical product in a view of efficiency, component count, temperature and etc.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2000-2007
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• 2016

Generally, in order to implement the CRM(Critical Conduction Mode), the analog controller is used rather than a digital controller because the control is simple and uses less power. However, according to the semiconductor technology development and various user needs, digital control system based on a DSP is on the rise. Therefore, in this paper, the CRM bridgeless PFC converter based on a digital control is proposed. It is necessary to detect the inductor current when it reaches zero and peak value, for calculating the on time and off time by using the current information. However, in this paper, the on-time and off-time are calculated by using the proposed algorithm without any current information. If the switching-times are calculated through the steady-state analysis of the converter, they do not reflect transient status such as starting-up. Therefore, the calculated frequency is out of range, and the transient current is generated. In order to solve these problems, limitation method of the on-time and off-time is used, and the limitation values are varied according to the voltage reference. In addition, in steady state, depending on the switching frequency, the inductance is varied because of the resonance between the inductor and the parasitic capacitance of the switching elements. In order to solve the problem, inductance are measured depending on the switching frequency. The measured inductance are used to calculate the switching time for preventing the transient current. Simulation and experimental results are presented to verify the proposed method.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1168-1177
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• 2015

This paper presents a scheme to improve the line current distortion of power factor corrector (PFC) topology at the zero crossing point using a predictive control algorithm in both the continuous conduction mode (CCM) and discontinuous conduction mode (DCM). The line current in single-phase PFC topology is distorted at the zero crossing point of the input AC voltage because of the characteristic of the general proportional integral (PI) current controller. This distortion degrades the line current quality, such as the total harmonic distortion (THD) and the power factor (PF). Given the optimal duty cycle calculated by estimating the next state current in both the CCM and DCM, the proposed predictive control algorithm has a fast dynamic response and accuracy unlike the conventional PI current control method. These advantages of the proposed algorithm lower the line current distortion of PFC topology. The proposed method is verified through PSIM simulations and experimental results with 1.5 kW bridgeless PFC (BLPFC) topology.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.1
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• pp.44-53
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• 2020

A bridgeless single-stage AC-DC converter for wireless power charging systems is proposed. This converter is composed of a PFC stage and a three-level hybrid DC-DC stage. The proposed converter can control the wide output voltage (200-450 V_DC) by the variable link voltage and the pulse-width voltage applied to the primary resonant circuit due to the phase-shifted modulation at a fixed switching frequency. Moreover, the input power factor and the total harmonic distortion can be improved by using the proposed converter. A 1 kW prototype was fabricated and validated through experimental results and analysis.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.377-378
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• 2012

DC-DC 컨버터를 인터리브 방식으로 제어하면 출력 전류 리플이 저감되고, 출력 필터 커패시터의 용량을 줄일 수 있다. 하지만 공진(Resonance)을 통해 전력을 전달하는 LLC 공진형 컨버터의 경우 회로를 구성하는 공진 인덕터 및 공진 커패시터의 오차(Tolerance)로 인해 출력 전류 리플의 언밸런스가 심화될 수 있다. 따라서 이를 개선할 수 있는 방법에 대한 연구가 필요하다. 본 논문에서는 Y결선 정류기를 이용한 3상 인터리브드 LLC 공진형 컨버터의 출력 전류 리플 밸런싱 방법을 제안한다. 제안된 방법은 3상 인터리브드 LLC 공진형 컨버터와 각 LLC 공진형 컨버터 앞단의 Bridgeless PFC가 독립적으로 추가되어 회로가 구성된다. 3상 인터리브드 LLC 공진형 컨버터는 분할된 위상으로 비독립적으로 제어하며 출력 전류 리플의 언밸런스를 Bridgeless PFC의 출력 전압을 가변함으로써 개선할 수 있는 방법을 제안하고 이를 시뮬레이션(PSIM)을 통해 제안된 밸런싱 방법을 검증하였다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.92-94
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• 2019

양방향 스위치를 가지는 Bridgeless PFC 컨버터(BBPFC)는 구조상 복잡한 플로팅 게이트 드라이버를 활용함에도 불구하고 좋은 공통모드 잡음 즉, Common-Mode (CM) 노이즈 특성과 간단한 제어 방법으로 인해 많은 브리지리스 PFC 컨버터 중에서도 고전력 응용분야에서 매우 매력적인 토폴로지이다. 이러한 BBPFC는 도통 경로 상에 위치한 정류 다이오드의 역회복 특성의 상대적인 편차를 활용하여 전력 밀도를 감소시키지 않고도 좋은 공통모드 (CM) 노이즈 특성의 확보가 가능하다. 하지만 이러한 장점을 가지는 BBPFC 구조를 고전력 서버용 전원장치분야에서 활용할 경우, 이미 등록된 특허로 인해 매우 높은 개런티를 지불해야 하므로 그 활용이 매우 제한적이다. 따라서, 본 논문에서는 이미 등록된 특허를 회피하고, 동시에 기존 BBPFC 회로가 가지는 단점인 플로팅 게이트 드라이버를 활용하는 단점을 개선하는 새로운 형태의 브리지리스 PFC 컨버터를 제안한다. 제안된 컨버터는 기존 BBPFC가 가지는 장점인 좋은 (CM) 노이즈 특성을 가지며, 동시에 높은 효율을 달성 할 수 있다. 또한 제안된 컨버터의 경우, 복잡한 플로팅 형태의 게이트 드라이버 회로가 아닌 간단한 부트스트랩 회로를 활용하여 회로를 운용할 수 있다. 더불어 제안된 컨버터는 입력의 양과 음의 주기에서 단 하나의 스위치를 사용하여 회로를 구동할 수 있기 때문에 기존회로 대비 적은 손실을 가져 높은 효율의 획득이 가능하다. 본 논문에서는 제안된 구조에 대해 하이라인 $230V_{RMS}$ 입력과 800W / 400V 출력의 조건을 적용하여 제안하는 구조의 효용성을 검증하고자 한다.