• Journal of IKEEE
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• v.20 no.3
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• pp.314-317
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• 2016

Recently, efforts to maximize battery life in progress with an increase in the demand for portable devices. In this paper, we propose multi-phase buck converter with fast transient response. Multi-phase buck converter may be used for the output capacitor of small size because the ripple cancellation effect, it is possible to use an inductor having an inductance less. The portable device for quick change from standby mode to active 4-phase design structure was given a fast transient response. The proposed multi-phase buck converter was fabricated using a 0.18 um CMOS process and the supply voltage ranges from 2.7V to 3.3V, the maximum load current is 500mA and settling time is 10us.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.190-196
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• 2013

It presents a unification of buck-boost and flyback converter for driving a cascaded H-bridge multilevel inverter with a single independent DC voltage source. Cascaded H-bridge multilevel inverter is useful to make many output voltage levels for sinusoidal waveform by combining two or more H-bridge modules. However, each H-bridge module needs an independent DC voltage source to generate multi levels in an output voltage. This topological characteristic brings a demerit of increasing the number of independent DC voltage sources when it needs to increase the number of output voltage levels. To solve this problem, we propose a converter combining a buck-boost converter with a flyback converter. The proposed converter provides independent DC voltage sources at back-end two H-bridge modules. After analyzing theoretical operation of the circuit topology, the validity of the proposed approach is verified by computer-aided simulations using PSIM and experiments.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.7
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• pp.1039-1048
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• 2013

Generally, the buck converter controller was designed to control output voltage of the converter. However, design of the controller in photovoltaic power conditioning system is different from general design. the controller in photovoltaic power conditioning system controls input voltage of the converter(output voltage of the solar cell) for MPPT(Maximum Power Point Tracking). This paper proposes novel buck converter model which can control input voltage of the converter. We integrate this model with a model of solar cell. and linearize at the operating point(MPP). In addition, we determine whether or not suitable for the general linear controller design into small and large signal analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.1
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• pp.54-61
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• 2009

This paper proposes the 2nd-order SDSDM (Space Dithered Sigma-Delta Modulation) for performance improvement of a buck converter. The PWM (Pulse Width Modulation) has a drawback in that power spectrum tends to be concentrated around the switching frequency. The resulting harmonic spikes cause a EMI(Electromagnetic Interference) and switching loss in semiconductor, etc. The 1st-order SDSDM scheme is a kind of DSDM for reducing these harmonic spikes. In this scheme, a switching frequency is spread through random dither generator placed on input part. In experimental result, the proposed 2nd-order SDSDM is confirmed by applying to a buck converter.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.38-39
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• 2017

This paper proposes a new control method for an AC-DC Buck converter which is utilized as a front-end converter of a 2-stage high power density adapter. In the conventional adapter applications, 2-stage configuration shows higher power transfer efficiency and higher power density than those of the single stage flyback converter. In the 2-stage AC-DC converter, the boost converter is widely used as a front-end converter. However, an efficiency variation between high AC line and low AC line is large. On the other hand, the proposed conduction band control method for a buck front-end converter has an advantage of small efficiency variation. In the proposed control method, switching operation is determined by a band control voltage which represents output load condition, and an AC line voltage. If the output load increasesin low AC line, the switching operation range is expanded in half of line cycle. On the contrary, in light load and high line condition, the switching operation is narrowed. Thus, the proposed control method reduces switching loss under high AC line and light load condition. A 60W prototype which is configured the buck and LLC converter with the proposed control method is experimented on to verify the validity of the proposed system. The prototype shows 92.16% of AC-DC overall efficiency and 20.19 W/in 3 of power density.

• Journal of Power Electronics
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• v.15 no.4
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• pp.899-909
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• 2015

A dual-input boost-buck converter with coupled inductors (DIBBC-CI) is proposed as a thermoelectric generator (TEG) power conditioner with a wide input voltage range. The DIBBC-CI is built by cascading two boost cells and a buck cell with shared inverse coupled filter inductors. Low current ripple on both sides of the TEG and the battery are achieved. Reduced size and power losses of the filter inductors are benefited from the DC magnetic flux cancellation in the inductor core, leading to high efficiency and high power density. The operational principle, impact of coupled inductors, and design considerations for the proposed converter are analyzed in detail. Distributed maximum power point tracking, battery charging, and output control are implemented using a competitive logic to ensure seamless switching among operational modes. Both the simulation and experimental results verify the feasibility of the proposed topology and control.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1422-1432
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• 2017

This paper presents a buck-boost converter-based bipolar pulse generator, which is able to generate bipolar exponential pulses across a resistive load. The concept of the proposed approach depends on operating the involved buck-boost converters in discontinuous current conduction mode with high-voltage gain and enhanced efficiency. A full design of the pulse generator and its passive components is presented to ensure generating the pulses with the desired specifications (rise time, pulse width, and pulse magnitude) for a given load resistance and input dc voltage. In case of moderate pulsed output voltages (i.e. few of kV), one module of the presented bipolar generator can be employed. While in case of high-voltage pulsed output, multi-module version can be employed, where each module is fed from an isolated dc source and their outputs are connected in series. Simulation models for the proposed approach are built to elucidate their performance in case of one-module as well as multi-module based generator. Finally, a scaled-down prototype for one-module of buck-boost converter-based bipolar pulse generator is implemented to validate the proposed concept.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.11
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• pp.2015-2021
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• 2008

Recently, with the growth of photovoltaic system, many researchers and companies have concerned about the multi-level inverter which has an efficiency of boosting voltage. In this paper a novel structure of multi-level converter for reducing ripple of output voltage is proposed. In the proposed converter Buck converters are connected in series to generate the output voltage and the ripple of output voltage can be reduced compared with the exiting Buck converter. Especially when outputting lower output voltage the number of acting switching elements is less and the result of ripple reducing is more obvious. This paper implements a multi-level switching function based on the FPGA.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.3
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• pp.373-379
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• 2019

Nowadays, the IoT portable electronic devices have become more useful and diverse, so they require various supply voltage levels to operate. This paper presents a DC-DC buck converter with pulse width modulation (PWM) for portable electronic devices. The proposed step-down DC-DC converter consists of passive elements such as capacitors, inductors, and resistors and an integrated chip (IC) for signal control to reduce power consumption and improves ripple voltage with the resolution. The proposed DC-DC converter is simulated and analyzed in PSPICE circuit design platform, and implemented on the prototype PCB board with a Texas Instruments LM5165 IC. The proposed buck converter is showed 92.6% of peak efficiency including a load current range of 4-10 mA, 3.29 mV of the voltage ripple at 5 V output voltage for the supply voltage 12 V. Measured and Simulated power efficiency are made good agreement with each other.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.5 s.311
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• pp.28-35
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• 2006

This paper presents a new 3.3-1 V synchronous buck DC/DC converter that employs CMOS operational transconductance amplifiers (OTAs) as circuit-building blocks. An error amplifier OTA in a PWM circuit is compensated for to improve temperature stability. The temperature coefficient of the transconductance gain of the compensated OTA is less than $150\;ppm/^{\circ}C\;over\;0-100^{\circ}C$. The HSPICE simulation results of the $0.3{\mu}m$ standard CMOS technology show that the efficiency of the proposed converter is as high as 80% in the load current range of 40-125 mA. These results show that the proposed converter is adequate for use in battery-operated systems.