• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.749-753
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• 2003

This paper presents an output voltage regulation system using PWM Buck-Boost AC-AC converter for power qualify improvement of custom power. This paper proposes dynamic modeling of the system for control object and in addition, a controller design example. Therefore, system state equation is derived whereby the transfer function could be obtained. The paper shows a regulation controller for tracking the output voltage to the reference under specific operating point. Finally, this paper shows validity and practical applicability of the proposed modelling and system design by experimental results.

• Journal of IKEEE
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• v.18 no.1
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• pp.128-133
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• 2014

This paper suggest hysteretic buck converter using thermistor that can improve output ripple voltage according to temperature to improve. In case of high temperature where circuit is sensitive, it decides two comparable voltages high. And, in case of non-high temperature where circuit is stable, it decides two comparable voltages low, then it minimizes output ripple voltage. simulation result what is included in this paper describe that output ripple voltage is reduced more than 30mV by using suggested converter, and load regulation was 0.011mV/mA. Suggested circuit is suitable to power managing circuit that operate digital circuit requiring fast response and low power.

• Journal of IKEEE
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• v.24 no.1
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• pp.319-325
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• 2020

In this paper, a discontinuous-conduction mode (DCM) DC-DC buck converter is presented for mobile device applications. The buck converter consists of compensator for stable operations, pulse-width modulation (PWM) logic, and power switches. In order to achieve small hardware form-factor, the number of off-chip components should be kept to be minimum, which can be realized with simple and efficient frequency compensation and digital soft start-up circuits. Burst-mode operation is included for preventing the efficiency from degrading under very light load condition. The DCM DC-DC buck converter is fabricated with 0.18-um BCDMOS process. Programmable output with external resistors is typically set to be 1.8V for the input voltage between 2.8 and 5.0V. With a switching frequency of 1MHz, measured maximum efficiency is 92.6% for a load current of 100mA.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1283-1290
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• 2003

Recently, PWM Buck AC-AC Converter is widely employed in various industrial applications such as voltage and power regulator, electronic transformer, phase shifter and so on. This paper presents static and dynamic modeling and complete characteristic analysis of a PWM Buck AC-AC converter. Firstly, the three phase converter system is modelled by using DQ transformation whereby we can obtain basic characteristic equations such as voltage gain and power factor as well as state equation and transfer function for control. Secondly, based on the analysis, the feedforward-feedback control technique is also proposed to obtain instantaneous duty level change whereby very fast dynamic response is achieved. Finally, the experimental results show the validity of the modeling, analysis and control.

• Journal of IKEEE
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• v.18 no.3
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• pp.320-327
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• 2014

Recently, Importance of power management circuit technology is increased with the development of portable electric devices. This paper presents a high performance DC-DC buck converter for mobile applications. Especially, presented design have low ripple voltages and driving capability of large load current. A designed voltage mode 2-phase DC-DC converter is implemented in a $0.35{\mu}m$ CMOS process, and the overall size is $2.35{\times}2.35mm^2$. The peak efficiency is 91% with a 4MHz frequency and the maximum load current is 4A.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.10
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• pp.40-47
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• 2016

In this paper, a dual mode buck converter with an ability to change mode is proposed, which is suitable particularly for portable device. The problem of conventional mode control circuit is affected by load variation condition such as suddenly or slowly. To resolve this problem, the mode control was designed with slow clock method. Also, when change from the PFM(Pulse Frequency Modulation) mode to the PWM(Pulse Width Modulation) mode, to use the counter to detect a high load. And the user can select mode transition point in load range from 20mA to 90mA by 3 bit digital signal. The circuits are implemented by using BCDMOS 0.18um 2-polt 3-metal process. Measurement environment are input voltage 3.7V, output voltage 1.2V and load current range from 10uA to 500mA. And measurement result show that the peak efficiency is 86% and ripple voltage is less 32mV.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.100-101
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• 2017

This paper presents the dynamics of the current-mode controlled buck and boost converters, which are both connected to an ill-conditioned source. This paper investigates the origin of potential instability and demonstrates internal/external dynamics of the converters under adverse interactions with the source.

• 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.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.17-18
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• 2010

최근 전력변환기의 효율 증대를 위한 소프트 스위칭 및 동기형 DC/DC 컨버터에 대한 연구가 활발히 진행되고 있다. 따라서 본 논문에서는 동기형 Buck-Converter를 이용한 Full-Bridge DC/DC 컨버터의 ZVS 기법에 대하여 연구 하였으며, 제안된 방식의 타당성을 검증하기 위해 Psim을 이용한 시뮬레이션을 행하였다.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.347-348
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• 2010

본 논문에서는 기본적인 직류-직류 변환기 중 하나인 동기식 강압형 직류-직류 변화기를 디지털 제어로 구현함으로서 아날로그 제어기를 디지털 제어기로 변환 하는 과정에 관하여 설명한다. 먼저 전원단의 소신호 특성을 해석하여 제어대 출력전압의 전달함수를 찾아내고, 이것을 토대로 아날로그 제어기를 설계 하여 Simulink를 통하여 시뮬레이션을 수행하고, 설계된 아날로그 제어기를 바탕으로 Matlab을 이용한 Emulation 기법을 사용하여 디지털 제어기를 설계 한다. DSP(TMS320F28335)를 사용한 동기식 강압형 직류-직류 변환기에 설계된 디지털 제어기를 적용하여 안정도와 부하변동에 따른 응답 특성을 확인 한다.