• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.12
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• pp.106-112
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• 1996

A ZVT (zero voltage transition) converter for SRM (switched reluctance motor) drives is proposed in this study. By adding a ZVT-chopping switch in the front-end, all switches in the machine side converter can be operated without any chopping to regulate phase current. This allows the use of low-cost and slow-switching devices for the machine side converter. The ZVT circuitry allows high frequency operation of th echopping switch, which enhnaces the system dynamcis and phase-current ripples. High efficiency of th eintegrated converter is obtained due to low switching losses.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.409-412
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• 1998

In this paper, an improved soft switching forward dc/dc converter is proposed. The proposed converter is constructed by using non-dissipate snubbers in parallel with the main switch and output diode of the conventional forward converter. Due to use of the non-dissipative snubbers, the proposed converter achieves zero-voltage switching for all switching devices and output diodes without switching losses. The complete operating principles and experimental results will be presented.

• Journal of Power Electronics
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• v.7 no.1
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• pp.13-20
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• 2007

LLC resonant converters display many advantages over the conventional LC series resonant converter such as narrow frequency variation over wide range of load and input variation and zero voltage switching even under no load conditions. This paper presents analysis and design consideration for the half bridge LLC resonant converter. Using the fundamental approximation, the gain equation is obtained, where the leakage inductance in the transformer secondary side is also considered. Based on the gain equation, the practical design procedure is investigated to optimize the resonant network for a given input/output specifications. The design procedure is verified through an experimental prototype of the 115W half-bridge LLC resonant converter.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.1866-1868
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• 1998

This paper propose zero voltage and zero current switching buck converter using a single switch. This converter is electrically equivalent to two basic buck converter in a cascade. Proposed converter is switching at high frequency and operate in high efficiency at wide load range due to resonant switching.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.899-901
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• 1993

LARGE SYNCHRONOUS GENERATORS USED IN CONNECTION WITH COMPRESSOR, TURBINE, IN MOST CASE, NEED THE HELP OF AN ELECTRICAL DRIVES FOR STARTING IN GAS TURBINES. NOWDAYS, THE STATIC FREQUENCE CONVERTER STARTING SYSTEM is EMPLOYED IN POWER PLANT. THIS PAPER DESCRIBES TORQUE CONVERTER, STATIC FREQUENCY CONVERTER AND COMPARSION OF TWO SYSTEMS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.864-870
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• 2017

This paper describes a Dual Buck Converter with mode control using variable Frequency to Voltage for portable devices requiring wide load current. The inherent problems of PLL compensation and efficiency degradation in light load current that the conventional hysteretic buck converter has faced have been resolved by using the proposed Dual buck converter which include improved PFM Mode not to require compensation. The proposed mode controller can also improve the difficulty of detecting the load change of the mode controller, which is the main circuit of the conventional dual mode buck converter, and the slow mode switching speed. the proposed mode controller has mode switching time of at least 1.5us. The proposed DC-DC buck converter was implemented by using $0.18{\mu}m$ CMOS process and die size was $1.38mm{\times}1.37mm$. The post simulation results with inductor and capacitor including parasitic elements showed that the proposed circuit received the input of 2.7~3.3V and generated output of 1.2V with the output ripple voltage had the PFM mode of 65mV and 16mV at the fixed switching frequency of 2MHz in hysteretic mode under load currents of 1~500mA. The maximum efficiency of the proposed dual-mode buck converter is 95% at 80mA and is more than 85% efficient under load currents of 1~500mA.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.3
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• pp.266-274
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• 1991

This paper proposed the resonant DC-DC converter with constant switching frequency. Its output is controlled by the auxiliary switch which is attached in conventional MRC circuits. The average output voltage is equal to the average voltage of the auxiliary switch. If the on time of the auxiliary switch is short, output voltage is decreased. Because of using the multi resonant method, the power loss from the parasitic elements can be decreased. Experimental performance of DF ZVS Forward MRC topology with switching frequency of 1MHz is presented.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1041-1044
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• 2003

In this paper, a new CMOS fully integrated frequency-to-digital converter is proposed. The operation of the proposed circuit is based on a pulse-shrinking delay element. In the proposed circuit, a resolution of the converted digital output can be easily improved by increasing the number of the pulse-shrinking element. Also the input frequency range can be easily changed through controlling bias voltage in the pulse-shrinking element. The simulation of the designed circuit carried out by HSPICE using the CMOS 0.35${\mu}{\textrm}{m}$ process technology.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1991.10a
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• pp.103-106
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• 1991

Spectrum Analyzer is a useful measure instrument to display the distributed power of electrical signal as a function of frequency. It adopts the superheterodyne receiver, which mixes RF with L0 to output IF. So in this paper, two GHz-order microstrip low-pass filters, 2-section wilkinson power divider, and singly balanced diode mixer have been designed and implemented necessary to make the frequency converter applied to RF spectrum analyzer.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.159-160
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• 2015

Recently, it is increased to use the portable device with small size. It is also increasing for demand of a small size adapter. To reduce the size of components, switching frequency has to be increased. But it causes higher switching loss and temperature of components. Especially, the temperature of adapter must be limited because adapter can be easily touched when portable device is being charged. To reduce temperature of adapter, high efficiency is essential. To solve this problem, this paper proposes design of resonance frequency optimization for LLC converter with high efficiency and low temperature of passive components.