• 한국통신학회논문지
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• 제34권7A호
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• pp.568-573
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• 2009

본 논문에서 0.13um CMOS 공정으로 설계된 배터리 기반 휴대용 통신 시스템 구동용의 온칩 시동회로를 갖는 스텝다운 CMOS DC-DC 변환기를 제안하였다. 1MHz의 스위칭 주파수를 기반으로 설계된 벅 변환기에는 온칩 시동회로와 커패시터 멀티플라이어 기법을 이용한 보상회로를 포함시켰다. 칩 측정 결과 2.5V ${\sim}$3.3V의 입력 전압을 1.2V로 강압시키는데 최대 87.2%의 효율을 갖는다. 최대 부하 전류, 출력 전류 리플 및 전압 리플은 각각 500mA, 25mA, 24mV 이다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.347-348
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• 2017

This paper presents a new current balancing operation for LED using double-step-down dc-dc converter. The two output currents of the proposed converter can be balanced by charge balance condition although the two output resistances are different. In addition, voltage stresses of the switches of the proposed converter are lower than those of interleaved buck converter. To verify the operation of the proposed converter, simulation program is used.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권1호
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• pp.67-76
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• 2012

Due to the increasing amount of applications of power electronic ac-dc converters, it is necessary to design a single-stage converter that can reliably perform both buck and boost operations. Traditionally, this can be achieved by double-stage conversion (ac/dc-dc/dc) which ultimately leads to less efficiency and a more complex control system. This paper discusses two types of modern ac-dc converters. First, the novel impedance-source ac-dc converter, abbreviated as custom Z-source rectifier, is analyzed; and then, switched inductor (SL) Z-source ac-dc converter is proposed. This paper describes the Z-source rectifiers' operating principles, the concepts behind them, and their superiorities. Analysis and simulation results show that the proposed custom Z-source rectifier can step up and step down voltage; and the main advantage of the SL Z-source ac-dc converter is its high step-up capability. Low ripple of the output dc voltage is the other advantage of the proposed converters. Finally, the SL Z-source ac-dc converter is compared with the custom Z-source ac-dc converter.

• 한국산학기술학회논문지
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• 제15권3호
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• pp.1700-1706
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• 2014

본 논문에서는 휴대기기용 LED 백라이트를 위한 감압형 DC-DC 변환기를 제안한다. 제안하는 변환기는 4 MHz의 높은 주파수에서 동작하며, 이것은 파워 스테이지와 컨트롤 블록의 수동소자의 면적 감소효과를 가진다. 파워스테이지는 인덕터와 출력 커패시터, 파워트랜지스터, 피드백 저항으로 이루어지며, 컨트롤 블록은 펄스폭 변조기, 오차증폭기, 오실레이터 등으로 이루어진다. 회로는 $0.35{\mu}m$ 1-poly 4-metal BCD 공정을 사용하여 설계 검증 및 레이아웃 하였다. SPICE 모의 실험 결과 시비율이 0.4 이고, 입력전압이 3.7 V 일 때, 1.8 V의 출력 전압을 가지며, 출력전류는 100 mA를 가진다. 제안하는 회로는 기존의 25~50 mA보다 큰 출력을 나타내어 고휘도의 LED 센서 구동이 가능할 것으로 보이며, 4 MHz의 스위칭 주파수를 사용하여, 변환기의 실장 면적이 종래에 비하여 30 % 정도의 감소가능할 것으로 보인다.

• 전기학회논문지
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• 제66권10호
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• pp.1474-1480
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• 2017

This paper presents a new LED current balancing scheme using double-step-down dc-dc converter. With the proposed structure, the two channel LED currents are automatically balanced without using any dedicated control or auxiliary circuit. In addition, switching loss of the switching devices in the proposed LED driver is lower than that of the conventional buck LED driver. To verify the operation of the proposed LED driver, a hardware prototype is built and tested with different number of LED.

• Journal of Power Electronics
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• 제18권2호
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• pp.343-355
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• 2018

A wide-voltage-conversion range bidirectional DC-DC converter is proposed in this paper. The topology is comprised of one typical LC energy storage component and a special common grounded asymmetric H-bridge with four active power switches/anti-parallel diodes. The narrow output PWM voltage is generated from the voltage difference between two normal (wider) output PWM voltages from the asymmetric H-bridge with duty cycles close to 0.5. The equivalent switching frequency of the output PWM voltage is double the actual switching frequency, and a wide step-down/step-up ratio range is achieved. A 300W prototype has been constructed to validate the feasibility and effectiveness of the proposed bidirectional converter between the variable low voltage side (24V~48V) and the constant high voltage side (200V). The slave active power switches allow ZVS turn-on and turn-off without requiring any extra hardware. The maximum conversion efficiency is 94.7% in the step-down mode and 93.5% in the step-up mode. Therefore, the proposed bidirectional topology with a common ground is suitable for energy storage systems such as renewable power generation systems and electric vehicles with a hybrid energy source.

• Journal of Power Electronics
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• 제19권6호
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• pp.1393-1402
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• 2019

This paper proposes a new power flow control method for soft-switched, four channel, five level resonant buck dc-dc converters. These converters have two input channels, which can be supplied from sources with identical or different voltages, and four output channels with arbitrary output voltages. They are specially designed to supply multilevel inverters. The design methodology for their power flow control has been developed considering a general case when the input voltages, output voltages and loads can be asymmetrical. A special emphasize is paid to the limitations and restrictions of operation. The theoretical studies are confirmed by numerical simulations and laboratory tests carried out at various operation points. Exploiting the advantages of the newly proposed power control strategy, the converter can supply five level inverters in dc microgrids, active filters, power factor correctors and electric drives. They can also play an interfacing role in renewable energy systems.

• 전력전자학회논문지
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• 제19권5호
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• pp.391-398
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• 2014

This paper presents a resonant step-down DC/DC converter to reduce the voltage stresses of a 3-phase inverter module under the three-phase AC utility line condition. Under this condition, a conventional 3-phase inverter module suffers from high voltage stresses as a result of the high rectified DC link voltage; hence, a high-cost high-voltage-rating inverter module must be used. However, using the proposed converter, a low-cost low-voltage-rating inverter module may be adopted to drive the motor even under the 3-phase AC line condition. The proposed converter, which can be realized with small size inductor and low-voltage-rating semiconductor devices, operates at a high-efficiency mode because of the zero-current switching operations of all the semiconductor devices. The operational principles are explained and a design example is provided in the study. Experimental results demonstrate the validity of the proposed converter.

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.860-868
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• 2016

A bidirectional DC-DC converter (BDC) is an indispensable electrical unit for the electric vehicles (EVs). High efficiency, high power density, isolation, light weight and reliability are all essential requirements for BDC. In this paper, a 3 kW BDC for the battery charger of EVs is proposed. The proposed converter consists of a half-bridge structure on the primary side and an isolation transformer and a synchronous rectifier structure on the secondary side. With this topology, minimum number of switching devices are required for bidirectional power flow between the two dc buses of EVs. The easy implementation of the synchronous rectification gives advantages in terms of efficiency, cost and flexibility. The proposed BDC achieves high efficiency when operating in both modes (step-up and step-down). A 3 kW prototype is implemented to verify theoretical analysis and the performance of the proposed converter.

• Journal of Power Electronics
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• 제15권4호
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• pp.886-898
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• 2015

The design feasibility of a micro unidirectional DC transmission system based on an input-parallel output-parallel (IPOP) converter is analyzed in this paper. The system consists of two subsystems: an input-parallel output-series (IPOS) subsystem to step up the DC link voltage, and an input-series output-parallel (ISOP) subsystem to step down the output voltage. The two systems are connected through a transmission line. The challenge of the delay caused by the communication in the control system is addressed by introducing a ring communication structure, and its influence on the control system is analyzed to ensure the feasibility and required performance of the converter system under practical circumstances. Simulation and experiment results are presented to verify the effectiveness of the proposed design.