• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.10
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• pp.1832-1837
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• 2011

The fault current has increased due to the large power demand in power distribution system and network distribution system. To protect the power system effectively from the increased fault current, the superconducting fault current limiter (SFCL) has been notified. However, the conventional SFCL has some problems such as cost, operation, recovery, loss. To solve some problems, the hybrid superconducting fault current limiter using the fast switch was proposed. However, hybrid SFCL also has a problem that is protection coordination in power distribution system with hybrid SFCL. In this paper, the fault current limiting characteristics of hybrid SFCL with first half cycle non-limiting operation according to the fault angle, the resistance of superconducting element, and the magnitude of Current Limit Resistor (CLR) which are the components of hybrid SFCL were analyzed through the experiments.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.252-253
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• 2005

This paper describes a improvement of power control characteristics of ship's emergency lighting power supply(SELPS), that power factor(PF) is improved and electric power is controlled extensively, and power ON-OFF is controlled and system parameter monitored in remote distance by PC serial communication.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.23-24
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• 2011

In this paper, the 170W LLC half bridge DC-DC converter is designed for the lighting management system. The power conversion circuit consists of PFC and isolated LLC resonant converter. The topology of LLC half bridge resonant converter provides ZVS characteristic. And the stresses of voltage and current is smaller than that of the general resonant converters. So we can expect the higher efficiency. The optimal conditions for high efficiency were investigated through by experiment.

• Journal of Power Electronics
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• v.10 no.1
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• pp.14-20
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• 2010

In this paper, a tightly regulated triple output asymmetrical half bridge flyback (ASHF) converter is proposed. In order to regulate all output voltages, pulse frequency modulation (PFM), pulse width modulation (PWM) and phase delay (PD) are used simultaneously. In comparison with the conventional PWM-PD method, the interactions among the control variables are minimized and the operating range is increased. By the utilization of a multi winding transformer, the auxiliary transformer and the blocking capacitor are eliminated and the size and cost of the proposed converter is reduced. The operation principle of the converter is explained and the modes of operation are investigated. Based on the results, the steady state characteristics of the converter are explored. A 24V/10A, 12V/5A, 5V/10A hardware prototype is built and tested to verify the analysis results and the voltage regulation of the triple outputs of the proposed converter.

• Journal of Power Electronics
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• v.7 no.1
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• pp.21-27
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• 2007

This paper investigates a PID fuzzy controller for output voltage regulation of a current-doubler-rectified asymmetric half-bridge (CDRAHB) DC/DC converter. The controller is a PD-type fuzzy controller in parallel with a linear integral controller. The PD type fuzzy controller is for providing the varying gain at the different operating conditions to regulate the output voltage. The linear integral controller is for removing the steady-state error of the output voltage. In order to show the outstanding dynamic characteristics of the proposed controller, PSIM simulation studies are carried out and compared to the results for which the conventional loop gain design method is used.

• Journal of Power Electronics
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• v.7 no.3
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• pp.238-245
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• 2007

This paper considers the problem of regulating the output voltage of a current doubler rectified asymmetric half-bridge (CDRAHB) DC/DC converter via fuzzy integral control. First, we model the dynamic characteristics of the CDRAHB converter with the state-space averaging method, and after introducing an additional integral state of the output regulation error, we obtain the Takagi-Sugeno (TS) fuzzy model for the augmented system. Second, the concept of parallel distributed compensation is applied to the design of the TS fuzzy integral controller, in which the state feedback gains are obtained by solving the linear matrix inequalities (LMIs). Finally, numerical simulations of the considered design method are compared to those of the conventional method, in which a compensated error amplifier is designed for the stability of the feedback control loop.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2234-2236
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• 1997

The SIT, a Static Induction Transistor, is a semiconductor switch that is also called the power junction field-effect transistor (power JFET). Its characteristics are similar to a MOSFET except that its power level is higher and its maximum frequency of operation is lower. The normal method to protect against internal circuit transients of the form of di/dt or dv/dt is the use of snubber circuits. However, the limits of di/dt and dv/dt are high enough for the SIT that it is possible to operate without snubber circuits. SITs can be connected in parallel in order to cope with higher load currents that the value of an individual device rating. The purpose of this study is to investigate the parallel operation of SITs. In this experiment, we used a half-bridge inverter, the output of inverter is up to almost 1MHz and 2kW. Experimental results show that the operation of parallel connected SITs are facilitated individually good current sharing. The reason is the positive temperature coefficient of resistance of the SIT.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.1018-1023
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• 1998

This paper presents an effective control scheme incorporated in the voltage-fed half-bridge series resonant inverter for induction heating applications, which is based upon a load-adaptive tuned frequency tracking control strategy using PLL(Phase Locked Loop) and its peripheral control circuit. The proposed control strategy ensures a stable operation characteristics of overall inverter system and ZVS(Zero Voltage Switching0 operation in spite of sensitive load parameters variation as well as power regulation, specially in the non-magnetic heating loads. The simulation results and the performance characteristics in the steady-state are shown as compared with the experimental results for a prototype induction cooking system rated at 1.2kW.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.153-156
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• 2004

This paper presents a new circuit topology of the half-bridge resonant inverter. As the proposed half-bridge inverter can be operated in the load freewheeling modes, pulse width modulation (PWM) control method can be used for the output power control. The proposed half-bridge inverter should keep unity output displacement factor under the load-impedance varying conditions, if a new PWM control scheme based on the resonant frequency tracking algorithm is adopted. In this paper, electrical characteristics, and losses analysis of the proposed half-bridge resonant inverter are described. Simulation and experimental results of the prototype experimental setup to verify the validity of the proposed half-bridge resonant inverter are presented and discussed.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.203-205
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• 2006

This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit incorporating boost-half-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switching mode and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft switching (ZVS) operation ranges and the power dissipation as compared with those of the previously developed high-frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation (PWM) and pulse density modulation (PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.