• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.4
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• pp.330-336
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• 2012

In this paper, novel zero-voltage-transition(ZVT) synchronous buck converter of pulse-width-modulation(PWM) method is proposed to utilize auxiliary circuit. In this proposed scheme, designed to operate low output voltage for portable system and applied synchronous scheme to improve efficiency. Also proposed circuit is designed to do soft-switching operation in every switch. In this paper, the circuit operation is explained and analysed, and design guidelines are presented. To verify the availability of the proposed circuit, experiment and simulation is carried out.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.376-378
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• 2008

A new family of single-phase Z-source ac-ac converter(SZAC) based on single-phase matrix converter (SPMC) is proposed in this paper. Compared to conventional Z-source ac-ac converter, the proposed SZAC has unique feature: providing a wide range of output ac voltage with buck/boost in-phase (maintaining phase angle) and buck/boost out-of-phase (reversing phase angle) operation. A new commutation strategy is used to eliminate voltage spikes on switches. The operating principle of the proposed SZAC is presented. Analysis and experimental results are also presented.

• Journal of Power Electronics
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• v.9 no.3
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• pp.410-417
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• 2009

This paper represents a design and implementation of a digital controller for a multi-phase synchronous buck converter (SBC) using a digital signal processor (DSP). The multi-phase SBC has generally been used for a voltage regulation module (VRM) of a microprocessor because of its high current handling capability at a low output voltage. The VRM requires high control performance of tight output regulation, high slew rate, and load sharing capability of multiple converters. In order to achieve these requirements, the design and implementation of a digital control system for a multi-phase SBC are presented in this paper. The digital PWM generation, current sensing, and voltage and current controller using a DSP TMS320F2812 are considered. The experimental results are provided to show the validity of the implemented digital control system.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1421-1428
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• 2015

The efficiency and reliability of the dual-buck inverter (DBI) were greatly improved by eliminating the shoot-through problem and optimally designing the freewheeling diode. The traditional DBI suffers from large harmonic components with low output voltage and large capacity output filter inductor. To overcome the aforementioned disadvantages, a modified DBI (MBDI) was proposed by adopting a quasi-resonant link and pulse density modulation (PDM). This paper first introduces the working principle of the MBDI and PDM, and then the selection principle of system parameters is presented. Finally, a mathematical model of the MBDIis built, and an experiment prototype is set up. Simulation and experimental results verify the correctness of the theoretical analysis and the feasibility of the scheme.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1208-1216
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• 2014

Mismatch between switching frequency and circuit parameters often occurs in industrial applications, which would lead to instability phenomena. The bifurcation behavior of $V^2$ controlled buck converter is investigated as the pulse width modulation period is varied. Nonlinear behavior is analyzed based on the monodromy matrix of the system. We observed that the stable period-1 orbit was first transformed to the period-2 bifurcation, which subsequently changed to chaos. The mechanism of the series of period-2 bifurcations shows that the characteristic eigenvalue of the monodromy matrix passes through the unit circle along the negative real axis. Resonant parametric perturbation technique has been applied to prevent the onset of instability. Meanwhile, the extended stability region of the converter is obtained. Simulation and experimental prototypes are built, and the corresponding results verify the theoretical analysis.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.171-172
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• 2012

본 논문에서는 Cascade buck-boost 컨버터 토폴로지에서 인덕터 전류 리플 손실을 감소시켜 효율 향상시키는 최적 스위칭 방법을 제시한다. 효율을 높이기 위한 최적 스위칭 방법은 다양한 방식으로 듀티크기와 위상을 변화시켜 인덕터 전류 리플로 인해 발생하는 손실을 비교하여 최소화하는 방식을 채택한다. 또한, 제시된 방법은 100W급 Test bed를 통해 타당성을 검증한다.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.175-176
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• 2012

본 논문에서는 동기정류 및 부트스트랩 회로를 이용한 Cascade Buck-Boost 컨버터의 전압 제어 및 동작 모드 변경 기법을 제안한다. 제안한 방법은 기존의 제어 방법에 비해 모든 전압 영역에서 안정적으로 승 강압 모드 변경이 가능하며 높은 효율을 갖는다. 이의 검증을 위해 우선 다양한 제어 기법을 소개하고, 각각을 전압 제어 특성 및 효율 측면에서 실험적으로 비교한다.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.193-194
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• 2012

The bidirectional boost-buck chopper type AC voltage regulator is presented in this paper. The main characteristic of the AC chopper is the fact that it generates an output AC voltage larger or lower than the input AC one, depending of the instantaneous duty-cycle. Boost-buck chopper type AC voltage regulator, derived from the DC chopper modulated method, is a kind of direct AC-AC voltage converter and has many advantages: such as fast response speed, low harmonics and high power factor. It adopts high switching frequency AC chopper technique and can do wide range step less AC voltage regulation.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.821-824
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• 2005

This paper presents a technique to evaluate torque and speed characteristics of induction motor with the Dynamometer. The simple Dynamometer controlled via microcontroller and displayed by computer. The Microcontroller generates the PWM (Pulse Width Modulation) signal and control the duty cycle of signal for control braking level. The Buck converter is a braking unit which uses IGBT as switch in circuit. The output current of the Buck converter and output voltage of tacho generator are converted to digital signals and analyzed by microcontroller. The signals are then sent to computer for displaying torque and speed responds independent on the braking time. The test results of the Dynamometer in this research can coreectly predict the torque and speed response under reasonable tests. Moreover, this Dynamometer is easy and inexpensive to make.

• IEIE Transactions on Smart Processing and Computing
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• v.6 no.1
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• pp.47-52
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• 2017

Inductor in high power converter system increases production cost, volume and core loss proportional to the power. To decrease these disadvantages, this paper analyzed the characteristic of parallel-inductor and coupled-inductor in interleaved system with simulation. As a result, it is confirmed that two-phase interleaved non-coupled buck-converter has the best characteristic among three types converter.