• Journal of Power Electronics
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• v.2 no.4
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• pp.288-296
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• 2002

In this paper, a high frequency transformer - assisted auxiliary active resonant commutated snubber (HFTA-ARCS) for voltage source soft switching pulse width modulated power conversion circuits is presented. A three phase voltage source type soft switching inverter incorporating HFTA-ARCS circuits in its three bridge legs can reduce current rating of auxiliary active power switches and has sensorless simplified control scheme which any specified boost current management is not required for soft switching. Its operation principle and digital control scheme are described and a practical design method of circuit parameters on this HFTA-ARCS circuit is also introduced on the basis of computer simulation. Moreover, this space voltage vector modulated soft switching inverter system with DSP-based digital control scheme Is discussed and its effectiveness is proved on the basis of performance evaluations. The operating performances of this inverter system are also compared with those of conventional three-phase hard switching inverter under practical conditions of specified parameters.

• Journal of the Korean Society of Radiology
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• v.4 no.4
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• pp.11-16
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• 2010

In this paper, including the X-ray high voltage resonant inverter generators and high frequency high voltage transformer operating systems is proposed. X-ray generator removes the noise and was smaller, 50[kHz] to work more with the driving frequencies, and that occurred when the normal power supply available due to noise, survey the conditions and solve the problems of the poor was a problem. In addition, X-ray tube voltage, frequency controllers and tube current controller filament heating voltage transformer for high frequency transformer design and manufacture of doing X-ray devices were to become more efficient operation.

• Journal of Power Electronics
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• v.13 no.3
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• pp.329-338
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• 2013

In this paper, the charging characteristics of series resonant type high voltage capacitor chargers considering the transformer stray capacitance have been studied. The principles of operation for the four operational modes and the mode changes for the four different switching frequency sections are explained and analyzed in the range of switching frequency below the resonant frequency. It is confirmed that the average charging currents derived from the above analysis results have non-linear characteristics in each of the four modes. The resonant current, resonant voltage, charging current, and charging time of this capacitor charger as variations of the switching frequency, series parallel capacitance ratio ($k=C_p/C_s$), and output voltage are calculated. From the calculation results, the advantages and disadvantages arising from the parallel connection of this stray capacitance are described. Some methods to minimize charging time of this capacitor charger are suggested. In addition, the results of a comparative test using two transformers whose stray capacitances are different are described. A 1.8 kJ/s prototype capacitor charger is assembled with a TI28335 DSP controller and a 40 kJ, 7 kV capacitor. The analysis results are verified by the experiment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.16-21
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• 2005

In paper, propose new partial resonance ZCS PWM controlled High frequency insulating Full-bridge DC/DC converter not using exciting current of high frequency transformer. It is compared with the existing principles in characteristics. It also realizes a widely stabilized ZVS operating using new ON-OFF control method at synchronized power rectification MOSFET of high frequency insulating transformer secondary. Besides, it is brought over 97[%] measurement efficiency by proposed DC-DC converts. It is proved effectiveness of new methods using DC UPS PWM rectifier as switching power supply.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.1
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• pp.33-39
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• 2005

Comparing with the conventional transformer without the air gap, a contactless transformer with the large air gap between the long primary winding and the secondary winding has increased leakage inductance and reduced magnetizing inductance. For transferring the primary power to the secondary one, the high frequency series resonant converter has been widely used for the contactless power supply system with the large air gap and the increased leakage inductance of the contactless transformer However, the high frequency series resonant converter has the disadvantages of the low efficiency and high voltage gain characteristics in the overall load range due to the large air gap and the circulating magnetizing current. In this paper, the characteristics of the high efficiency and unit voltage gain are revealed in the proposed three-level series-parallel resonant converter. The results are verified on the simulation based on the theoretical analysis and the 5kW experimental prototype.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1951-1953
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• 2004

In this study, we propose a small high voltage power supply which use a half-bridge ZCS resonant and Cockroft-Walton on circuit, for ESP (Electrostatic Precipitator). This power supply transfers energy from ZCS resonant inverter to step-up transformer and the transformer secondary is applied to the Cockroft-Walton circuit for generating high voltage as discharging source of electrodes. It is highly efficient because its amount of switching losses are reduced by virtue of the current resonant half-bridge inverter, and also due to the small size, low parasitic capacitance in the transformer stage owing to the low number of winding turns of the step up transformer secondary combined with the Cockroft-Walton circuit. From these results, the best operational condition is obtained at the switching frequency of 9 kHz and the duty ratio of 50 % in this ESP.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.247-255
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• 2013

In this paper, a soft switching DC-DC converter for AC module type photovoltaic (PV) module integrated converter is proposed. A push-pull converter is suitable for a low voltage PV AC module system because the step-up ratio of a high frequency transformer is high and the number of primary side switches is relatively small. However, the conventional push-pull converters do not have high efficiency because of high switching losses by hard switching and transformer losses (copper and iron losses) by high turns-ratio of the transformer. In the proposed converter, primary side switches are turned on at zero voltage switching (ZCS) condition and turned off at zero current switching (ZVS) condition through parallel resonance between secondary leakage inductance of the transformer and a resonant capacitor. Therefore the proposed push-pull converter decreases the switching loss using soft switching of the primary switches. Also, the turns-ratio of the transformer can be reduced by half using a voltage-doubler of secondary side. The theoretical analysis of the proposed converter is verified by simulation and experimental results.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1383-1386
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• 2005

Non-isolated OSAKA Converter, which removes a three-phase transformer, is described in this paper. The converter switches once in every half cycle of an AC commercial power source. Therefore, it can solve many problems caused by the high frequency operation. The proposed converter achieves the soft-switching operation and the EMI noise can be reduced. In this circuit, the resonant capacitor, which is used for the soft-switching operation, is utilized for the improvement of an input current waveform. To achieve low cost and compact structure, non-isolated OSAKA converter removes a three-phase transformer of the OSAKA converter. By removing the three-phase transformer, three phase currents occur the interferences each other. To avoid the interference, a new switching method for non-isolated OSAKA converter is preposed. The converter can be constructed by the low-speed large power devices. The converter generates the low distorted input current waveforms with high power factor.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.3
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• pp.125-130
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• 2014

This paper is research result for a development of solar cell silicon ingot glowing(SCSIG) PWM converter system for 120[kW] 3[kA]. The system include 3-phase AC-DC rectifier diode converter of input voltage AC 460[V] and 60[Hz], DC-AC single phase full bridge PWM inverter of high frequency, AC-DC single-phase full wave rectifier using center-tapped of transformer for low voltage 50[V] and large current 3,000[A], carbon resistor load 0.2 [$m{\Omega}$]. PWM switching frequency for IGBT inverter control set 15KHz. The suggested researching contents are designed data sheets of power converter system, PSIM simulation, operating characteristics and analysis results of developed SCSIG system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.11
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• pp.33-41
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• 2014

This paper is research result for a development of sapphire silicon ingot glowing(SSIG) PWM converter system for 80kW 10kA. The system include 3-phase AC-DC diode rectifier of input voltage AC 380V and 60Hz, DC-AC single phase full bridge PWM inverter of high frequency, AC-DC single-phase full wave rectifier using center-tapped of transformer for low voltage 8.0V and large current 10,000A of output specification, tungsten resistor load 0.1[$m{\Omega}$]. PWM switching frequency for IGBT inverter control set 30kHz. The suggested researching contents are designed data sheets of power converter system, PSIM simulation, operating characteristics and analysis results of developed SSIG system. This paper propose