• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.34-36
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• 2007

A new soft switching boost converter is proposed in this paper. The conventional boost converter generates switching losses at turn on and off. Because of that, the whole system efficiency is reduced. The proposed converter utilizes soft switching method using an auxiliary switch and resonant circuit. Thus, the converter reduces switching losses lower than ones of hard switching method. The proposed soft switching boost converter can be applied to photovoltaic system, power factor correction circuit and so on.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.151-154
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• 1999

This paper presents a driving method of 3-phase 4-poles SRM(switched reluctance motor) drived by switching angle control. In this study, the switching angle is determined from approximated analysis and computer simulation by using MATLAB for high efficiency according to the speed and torque required by load, and then microcontroller controls the switching angle of asymmetrical inverter in SRM driver. Also, we experiment the maximum forque driving and maximum power driving by controlling switching angle available to electric vehicle.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.2
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• pp.162-168
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• 2008

In this paper, the RCF(Resistive Companion Form) analysis method is applied to analyze small signal stability of power systems including thyristor controlled FACTS(Flexible AC Transmission System) equipments such as TCSC(Thyristor Controlled Series Capacitor). The eigenvalue sensitivity analysis algorithm in discrete systems based on the RCF analysis method is presented and applied to the power system including TCSC. As a result of simulation, the RCF analysis method is very useful to precisely calculate the variations of eigenvalues or newly generated unstable oscillation modes after periodic switching operations of TCSC. Also the eigenvalue sensitivity analysis method based on the RCF analysis method enabled to precisely calculate eigenvalue sensitivity coefficients of controller parameters about the dominant oscillation mode after periodic switching operations in discrete systems. These simulation results are different from those of the conventional continuous system analysis method such as the state space equation and showed that the RCF analysis method is very useful to analyze the discrete power systems including periodically operated switching equipments such as TCSC.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.4
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• pp.383-390
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• 2014

This paper deals with novel soft-switching method for a bidirectional DC-DC converter in battery charging and discharging system. The proposed soft-switching method provides ZVS and ZCS at turn-on, and ZVS at turn-off of the switch in both charging and discharging operation modes. The soft switching condition can be obtained in wide load range, and provide low switching loss as well as low voltage spike at turn-off of the switch. Proposed method is analyzed in charging and discharging mode. Simulation and experimental results validate the usefulness of the proposed soft-switching method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.361-364
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• 2013

Since the non-overlapping gate driver used in conventional DC-DC boost converters generates fixed dead-times, the converters suffer from the body-diode conduction loss or the charge-sharing loss. A adaptive control method has been proposed to reduce these loses. In this method, however, occurrence of and overlapping time of two power transistors in CCM results in reduction of efficiency. In this paper, to overcome this problem a new adaptive control method in proposed, and a DC-DC boost converter with the proposed adaptive control and power switching has been designed in a 0.35um CMOS process. The designed converter outputs 3.3V from a input voltage of 2.5V. The switching frequency is 500kHz and the maximum power efficiency is 95.3% at a load current 150mA. The designed chip area is $1720um{\times}1280um$.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.310-312
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• 1989

From the viewpoint of an effective energy use, many method for reactive power compensation has been developed. Among of the reactive power compensation, this paper describes the relation of operation interpretation, filter, hysteresis width and switching time of current controlled PWM converter which has excellent reactive power compensation. This current controlled PWM convertor is excellent the view of reactive power compensation by current control method using hysteresis comparator method, but is required element of high response characteristics. Therefore this paper offers the series of data for system considering switching characteristics of switching element.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.11
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• pp.100-105
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• 2014

In this paper, Uninterruptible Power Supply(UPS) Inverter system using Carrier Frequency Modulated PWM (CFM-PWM) is proposed to reduced harmonics and electromagnetic noise. Power conversion of UPS system is executed by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI which deteriorate the reliability of the UPS system. This Problems improved by Random PWM switching method. The simulation results of the proposed system was compared with the system using conventional method using Matlab/Simulink. The results show that the output voltage and current harmonics of the proposed UPS system significantly decreased and spread into wide band area by the proposed Carrier Frequency Modulated PWM(CFM-PWM) method based on the Space Vector Modulation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.1
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• pp.20-26
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• 2009

In this paper, the switching mode conversion type pulse charger by fly-back converter method for lead battery of the solar cell generator equipment is proposed. And we propose the control circuit and design method of insulated switching mode convert type pulse charger by fly-back convert method in the lead battery. The proposed system can minimize the current consumption by digital pulse. Also the proposed system can generate the constant 10[KHz] frequency, transmit the signal with main control system in the power control system. And it supervises the state of lead battery using one chip micro processor. The proposed the switching mode conversion type pulse charger by the fly-back converter method can charge fast and stabilize lead battery with nominal value 12[V], 20[AH]. Also we propose the design procedure of the power control circuit for turn ratio of fly-back inductor and determining method of values such as the charging current, bulk current, partial current, over current value and fixed charging voltage. The experiment results for the voltage and current wave for partial, bulk, over and fixed charging period show the good charging effect and performance. And the PCB and internal coupling diagram of the switching mode conversion type pulse charger by fly-back converter method is presented.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.435-437
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• 2007

Authors propose a PFC(power factor correction) Buck-Boost AC-DC converter by soft switching method. The proposed converter for a discontinuous conduction mode eliminates the complicated control requirement and reduces the size of components. The input current waveform in the converter is got to be a sinusoidal form of discontinuous pulse in proportion to magnitude of ac input voltage under the constant duty cycle switching.Therefore,the input power factor is nearly unity and the control algorithm is simple. To achieve high efficiency system, the proposed converter is constructed by using a partial resonant technique. The control switches using in the converter are operated with soft switching for a partial resonant. The control switches are operated without increasing their voltage and current stresses by the soft switching method. The result is that the switching loss is very low and the efficiency of converter is high.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1306-1315
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• 2016

Modern power systems driven by high-power converters have become inevitable in view of the ever increasing demand for electric power. The total power loss can be reduced by limiting the switching losses in such power converters; increased power efficiency can thus be achieved. A reduced switching frequency that is less than a few hundreds of hertz is applied to power converters that produce output waveforms with high distortion. Selective harmonic elimination pulse width modulation (SHEPWM) is an optimized low switching frequency pulse width modulation method that is based on offline estimation. This method can pre-program the harmonic profile of the output waveform over a range of modulation indices to eliminate low-order harmonics. In this paper, a SHEPWM scheme for three-phase three-leg neutral point clamped inverter is proposed. Aside from eliminating the selected harmonics, the DC capacitor voltages at the DC bus are also balanced because of the symmetrical pulse pattern over a quarter cycle of the period. The technique utilized in the estimation of switching angles involves the firefly algorithm (FA). Compared with other techniques, FA is more robust and entails less computation time. Simulation in the MATLAB/SIMULINK environment and experimental verification in the very large scale integration platform with Spartan 6A DSP are performed to prove the validity of the proposed technique.