• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.7
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• pp.555-558
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• 2009

This paper presents a step-down converter IC for automotive applications. This device was designed for a 40 V/1 A high-power output for voltage reference of automotive IC. It provides 250kHz PWM (pulse width modulation) and PFM(pulse frequency modulation) according to load conditions. This device was simulated spectre of IC-design-tools and fabricated Dong-bu Hitec 0.35um BD350BA process.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.234-237
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• 2008

This paper deals with a new single-phase Z-source matrix converter (SZMC) topology. Unlike other conventional configurations, the proposed SZMC is not only a step-up frequency converter but also a step-down frequency converter and a voltage boost capability. Thus, the proposed SZMC is also called a frequency step-up/down and voltage step-up converter. A safe-commutation strategy is used in SZMC as free-wheeling operation to eliminate voltage spikes on switches. The operating principles and experimental results of the proposed SZMC are presented.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1445-1453
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• 2017

In this study, a new zero-voltage transition (ZVT) buck converter with coupled inductor using a synchronous rectifier and a lossless clamp circuit is proposed. The regular buck converter with tapped inductor has extended duty cycle for high step-down applications. However, the leakage inductance of the coupled inductor produced considerable voltage spikes across the switch. A lossless clamp circuit is used in the proposed converter to overcome this problem. The freewheeling diode was replaced with a synchronous rectifier to reduce conduction losses in the proposed converter. ZVT conditions at turn-on and turn-off instants were provided for the main switch. The synchronous rectifier switch turned on under zero-voltage switching, and the auxiliary switch turn-on and turn-off were under zero-current condition. Experimental results of a 100 W-100 kHz prototype are provided to justify the validity of the theoretical analysis. Moreover, the conducted electromagnetic interference of the proposed converter is measured and compared with its hard-switching counterpart.

• Journal of IKEEE
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• v.16 no.4
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• pp.335-342
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• 2012

This paper is studied on a new DCM-ZVS step up-down AC-DC converter of high performance, that is, high system efficiency and power factor correction (PFC). The switching devices in the proposed converter are operated by soft switching technique using a new quasi-resonant circuit, and are driven with discontinuous conduction mode (DCM) according to pulse width modulation (PWM). The quasi-resonant circuit uses a step up-down inductor and a loss-less snubber capacitor. The proposed converter with DCM also simplifies the requirement of control circuits and reduces the number of control components. The input AC current waveform in the proposed converter becomes a quasi-sinusoidal waveform proportional to the magnitude of input AC voltage under constant switching frequency. As a result, the proposed converter obtains low switching power loss and high efficiency, and its input power factor is nearly in unity. The validity of the analytical findings is confirmed by some computer simulation results and experimental results.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.304-309
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• 2005

This paper presents an electronic ballast using a step down converter, a low frequency inverter for high intensity short-arc discharge lamp. The proposed ballast is composed of a full-wave rectifier, a step down converter operated as a current source with power regulation and a low frequency inverter with external ignition circuit. The ignition circuit generates high voltage pulse of $3{\sim}5[kV]$ peak, 130[Hz] periodically. Moreover, it is able to reignite at regular intervals by protective circuit. As experimental results on the test, acoustic resonance phenomenon is eliminated by operating the low frequency square wave voltage and current. Lamp voltage, current and consumption power are measured 123.8[V], 8.1[A] and 1,002[W], respectively. It was confirmed that the designed ballast operate the lamp with a constant power.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1700-1706
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• 2014

In this paper, a step down converter for LED backlight of mobile application has been proposed. The converter which is operated with 4 MHz high switching frequency is capable of reducing mounting area of passive devices consists of a power stage and a control block. Circuit elements of the power stage are inductor, output capacitor, MOS transistors and feedback resistors. The control block consists of pulse width modulator, error amplifier and oscillator etc. Proposed step down converter has been designed and verified using a $0.35{\mu}m$ 1-poly 4-metal BCD process technology. Simulation results show that the output voltage is 1.8 V in 3.7 V input voltage, output current 100 mA which is larger than 25 ~ 50 mA in conventional 500 KHz driven converter when the duty ratio is 0.4.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1629-1638
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• 2016

Differential power processing (DPP) systems are among the most effective architectures for photovoltaic (PV) power systems because they are highly efficient as a result of their distributed local maximum power point tracking ability, which allows the fractional processing of the total generated power. However, DPP systems require a high-efficiency, high step-up/down bidirectional converter with broad operating ranges and galvanic isolation. This study proposes a single, magnetic, high-efficiency, high step-up/down bidirectional DC-DC converter. The proposed converter is composed of a bidirectional flyback and a bidirectional isolated switched-capacitor cell, which are competitively cheap. The output terminals of the flyback converter and switched-capacitor cell are connected in series to obtain the voltage step-up. In the reverse power flow, the converter reciprocally operates with high efficiency across a broad operating range because it uses hard switching instead of soft switching. The proposed topology achieves a genuine on-off interleaved energy transfer at the transformer core and windings, thus providing an excellent utilization ratio. The dynamic characteristics of the converter are analyzed for the controller design. Finally, a 240 W hardware prototype is constructed to demonstrate the operation of the bidirectional converter under a current feedback control loop. To improve the efficiency of a PV system, the maximum power point tracking method is applied to the proposed converter.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.15-16
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• 2012

This paper is study on a novel high efficiency step up-down converter using loss-less snubber capacitor. The proposed converter is accomplished that the turn-on operation of switches is on zero current switching (ZCS) by DCM. The converter is also applicable to a new quasi-resonant circuit to achieve high efficiency converter. The control switches using in the converter are operated with soft switching, that is, ZVS and ZCS by quasi-resonant method. The control switches are operated without increasing their voltage and current stresses by the soft switching technology. The result is that the switching loss is very low and the efficiency of the converter is high.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.1931-1933
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• 1998

In this paper, single-phase PWM AC to AC converter that operates with unit power factor and sinusoidal input line currents is presented. The output voltage of this converter is able to be obtain step up voltage as well as step down voltage. because the converter applies to operating method of buck-boost converter. The control of this converter is performed with PI control method. By using this control method low lipples in the output current and the voltage as well as fast dynamic response are achieved.

• Journal of IKEEE
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• v.10 no.2 s.19
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• pp.149-155
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• 2006

In this study, the design of low voltage DC-DC converter with low triggering ESD (Electro-Static Discharge) protection circuit was investigated. The purpose of this paper is design optimization for low voltage(2.5V to 5.5V input range) DC-DC converter using CMOS switch. In CMOS switch environment, a dominant loss component is not switching loss but conduction loss at 1.2MHz switching frequency. In this study a constant frequency PWM converter with synchronous rectifier is used. And zener Triggered SCR device to protect the ESD phenomenon was designed. This structure reduces the trigger voltage by making the zener junction between the lateral PNP and base of lateral NPN in SCR structure. The triggering voltage was simulated to 8V.