• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6B
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• pp.423-432
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• 2012

We design a control circuit that can switch input power between a rechargeable battery and a sensor communication device (mote) depending on the operating state of a solar cell as well as the active and sleep mode of a sensor MAC protocol. A mote that simply combines a solarcell and a rechargeable battery may die if there is not sunlight long. A battery is recharged if sunlight is sufficient and a device is in a sleep mode, and it supplies power if sunlight is low and the mote is in an active mode. A mote can switch its input power between solar cell and battery depending on the output level of a solar cell. During this switching, a mote may lose its state information due to the reset of a microprocessor by the transient power-off. A capacitor is used to cope with this phenomenon and also supplies power to a mote during a sleep mode. Experimental results show that the solar cell based mote operates in a very stable manner against the lack of sunlight long.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1891-1895
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• 2003

Switch-mode power supplies (SMPS) have become a major source of conducted electromagnetic interference (EMI) which is the combination between differential mode (DM) noise and common mode (CM) noise. This paper presents the conducted EMI reduction approach in flyback switched mode power supply by rerouting for circuit balance to reduce common mode noise. And differential mode noise can be reduce by adding $c_x$ capacitor across the input power line, and passive element to the gate drive of switching device MOSFET to slow down the switching times. This combination of our approach is the effective way to reduce the conducted EMI and it is also a cost effective for product design

• Journal of Power Electronics
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• v.8 no.1
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• pp.35-50
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• 2008

A zero-voltage-transition (ZVT) pulse width modulated (PWM) converter is a PWM converter with a single main power switch that has an auxiliary circuit to help it turn on with zero-voltage switching (ZVS). There have been many ZVT-PWM converters proposed in the literature as they are the most popular type of ZVS-PWM converters. In this paper, the properties and characteristics of several types of ZVT-PWM converters are reviewed. A new type of ZVT-PWM converter is then introduced, and the operation of a sample converter of this type is explained and analyzed in detail. A procedure for the design of the converter is presented and demonstrated experimentally. The feasibility of the new converter is confirmed with results obtained from an experimental prototype. Conclusions on the performance of ZVT-PWM converters in general are made based on the efficiency results obtained from the experimental prototypes of various ZVT-PWM converters of different types.

• Journal of Power Electronics
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• v.4 no.4
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• pp.237-245
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• 2004

In this paper, a two-switch high frequency flyback transformer linked zero voltage soft switching PWM DC-DC power converter implemented for distributed DC- feeding power conditioning supplies is proposed and discussed. This switch mode power converter circuit is mainly based on two main active power semiconductor switches and a main flyback high frequency transformer linked DC-DC converter in which, two passive lossless quasi-resonant snubbers with pulse current regeneration loops for energy recovery to the DC supply voltages composed of a three winding auxiliary high frequency pulse transformer, auxiliary capacitors and auxiliary diodes for inductive energy recovery discharge blocking due to snubber capacitors are introduced to achieve zero voltage soft switching from light to full load conditions. It is clarified that the passive resonant snubber-assisted soft switching PWM DC-DC power converter has some advantages such as simple circuit configuration, low cost, simple control scheme, high efficiency and lowered noises due to the soft switching commutation. Its operating principle is also described using each mode equivalent circuit. To determine the optimum resonant snubber circuit parameters, some practical design considerations are discussed and evaluated in this paper. Moreover, through experimentation the practical effectiveness of the proposed soft switching PWM DC-DC power converter using IGBTs is evaluated and compared with a hard switching PWM DC-DC power converter.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.301-303
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• 2001

In this paper we present a Capacitor Charging Power Supply (CCPS) using a series-resonant three-level inverter topology to improve voltage regulation and use semiconductor switches having low blocking voltage capability such as MOSFETs. This inverter can be operated with two modes, Full Power Mode (FPM) and Half Power Mode (HPM). In FPM inverter supplies the high frequency step up transformer with full DC-link voltage and in HPM with half DC-link voltage. HPM switching method will be adopted when CCPS output voltage reaches the preset target value and operates in refresh mode-charge is maintained on the capacitor. In this topology each semiconductor devices blocks a half of the DC-link voltage[2]. A 15kW, 30kV CCPS has been built and will be tested for an electric precipitator application. The CCPS operates from an input voltage of 500VDC and has a variable output voltage between 10 to 30kV and 1kHz repetition rate at 44nF capacitive load [3]. A resonant frequency of 67.9kHz was selected and a voltage regulation of $0.83\%$ has been achieved through the use of half power mode without using the forced cut off the switch current [1]. The theory of operation, circuit topology and test results are given.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1363-1374
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• 2009

This paper reviews the characteristics and technical trends in Power MOSFET technology that are leading to improvements in power loss for power electronic system. The silicon bipolar power transistor has been displaced by silicon power MOSFET's in low and high voltage system. The power electronic technology requires the marriage of power device technology with MOS-gated device and bipolar analog circuits. The technology challenges involved in combining power handling capability with finger gate, trench array, super junction structure, and SiC transistor are described, together with examples of solutions for telecommunications, motor control, and switch mode power supplies.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1819-1829
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• 2018

A three-phase, three-switch, and three-level boost-type PWM rectifier (Vienna rectifier) is proposed as an active front-end power factor correction (PFC) rectifier for telecom loads. The proposed active front-end PFC rectifier system is modeled by the switching cycle average model. The relation between duty ratios and DC link capacitor voltages is derived in terms of the system input currents. Furthermore, the feasible switching states are identified and applied to the proposed system to reduce the switching stress and DC ripples. A detailed equivalent circuit analysis of the proposed front-end PFC rectifier is conducted, and its performance is verified through simulations in MATLAB. Simulation results are verified using an experimental setup of an active front-end PFC rectifier that was developed in the laboratory. Simulation and experimental results demonstrate the improved power quality parameters that are in accordance with the IEEE and IEC standards.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.125-130
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• 2009

This paper reviews the characteristics technical trends in Power MOSFET technology that are leading to improvements in power loss for power electronic system. The power electronic technology requires the marriage of power device technology with MOS-gated device and bipolar analog circuits. The technology challenges involved in combining power handling capability with finger gate, trench array, super junction structure, and SiC transistor are described, together with examples of solutions for telecommunications, motor control, and switch mode power supplies.

• Journal of Power Electronics
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• v.14 no.4
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• pp.661-670
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• 2014

A new DC/DC converter with zero voltage switching is proposed for applications with high input voltage and high load current. The proposed converter has two circuit modules that share load current and power rating. Interleaved pulse-width modulation (PWM) is adopted to generate switch control signals. Thus, ripple currents are reduced at the input and output sides. For high-voltage applications, each circuit module includes two half-bridge legs that are connected in series to reduce switch voltage rating to $V_{in}/2$. These legs are controlled with the use of asymmetric PWM. To reduce the current rating of rectifier diodes and share load current for high-load-current applications, two center-tapped rectifiers are adopted in each circuit module. The primary windings of two transformers are connected in series at the high voltage side to balance output inductor currents. Two series capacitors are adopted at the AC terminals of the two half-bridge legs to balance the two input capacitor voltages. The resonant behavior of the inductance and capacitance at the transition interval enable MOSFETs to be switched on under zero voltage switching. The circuit configuration, system characteristics, and design are discussed in detail. Experiments based on a laboratory prototype are conducted to verify the effectiveness of the proposed converter.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1291-1293
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• 1998

Power MOSFETs are very important Devices in power circuit applications such as motor control, switch mode power supplies & telecommunicatioelectronics. In order to investigated the Avalanch Energy value of MOSFET due to Misalign. Some samples made under several different $P^+$ misalign and $N^+$ misalign. The relationship between evalanch energy value and misalign is investigated as well in this paper.