• Journal of the Semiconductor & Display Technology
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• v.17 no.3
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• pp.21-26
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• 2018

In this paper, the switching characteristics of the active clamp type flyback converter, which is deemed suitable for the miniaturization of the external power supply for home appliance, were analyzed and the process of reducing the switching loss was explained. The active clamp type flyback converter operating in the DCM has confirmed that the surge voltage of the main switch does not occur and the turn-off / on loss of the switch do not occur in principle. Also, in the case of the switch for synchronous rectifier, it was showed that the switch current showed half-wave rectified sinusoidal characteristic, and the switching loss was reduced. The switching characteristics of the experimental results gathered from 120 W class prototype were compared with the theoretical waveform in the steady-state and it was confirmed that the power conversion efficiency of the active clamp type flyback converter was maintained high due to the reduction of the switching loss.

• Journal of IKEEE
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• v.12 no.2
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• pp.110-117
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• 2008

This paper presents a new Insulated Gate Bipolar Transistor(IGBT) based on Non Punch Through(NPT) IGBT structure for power switching device. The proposed structure has adding N+ beside the P-base region of the conventional IGBT structure. The added n+ diffusion of the proposed device ensure device has faster turn-off time and lower forward conduction loss than the conventional IGBT structure. But, added n+ region can reduce th breakdown voltage and latching current density of the proposed device due to its high doping concentration. This problems can be overcome by using diverter on the right side of the device. In the simulation results, turn-off time of the proposed device is 0.3us and the on-state voltage drop is 3V. The results show that the proposed device has superior characteristic than conventional structure.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2446-2452
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• 2009

A Ceramic Metal-halide lamp is achieved by adding multiple metals to a basic mercury discharge. Because the vapor pressure of most metals is very much lower than mercury itself, metal-halide salts of the desired metals, having higher vapor pressures, are used to introduce the material into the basic discharge. The metal compounds are usually polyatomic iodides, which vaporize and subsequently dissociate as they diffuse into the bulk plasma. Metals with multiple visible transitions are necessary to achieve high photometric efficiency and good color. Compounds of Sc, Dy, Ho, Tm, Ce, Pr, Yb and Nd are commonly used. The maximum visible efficacy of a Ceramic Metal Halide lamp, under the constant of a white light source, is predicted to be about 450lm/W. This is controlled principally by the chemical fill chosen for a particular lamp. Current these lamps achieve 130lm/W and these life time are the maximum 16,000[hr]. So factors of performance lower are necessary to improve lamp performance. In this paper, we analyzed factors of performance lower by accelerated deterioration test. The lamp was operated with short duration turn-on/turn-off procedure to enhance the effect due to electrode sputtering during lamp ignition. The tested lamp that was operated with a longer turn-on/off(20/20 minutes) showed blackening, changed distance between electrodes and lowered color rendering & color temperature by losses of Dy at 421.18nm, I at 511nm, T1 at 535nm and Na at 588nm compared with the new lamp.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.216-225
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• 2006

This paper presents a new circuit topology of DC busline switch and snubbing capacitor-assisted full-bridge soft-switching PWM inverter type DC-DC power converter with a high frequency link for low voltage large current applications as DC feeding systems, telecommunication power plants, automotive DC bus converters, plasma generator, electro plating plants, fuel cell interfaced power conditioner and arc welding power supplies. The proposed power converter circuit is based upon a voltage source-fed H type full-bridge high frequency PWM inverter with a high frequency transformer link. The conventional type high frequency inverter circuit is modified by adding a single power semiconductor switching device in series with DC rail and snubbing lossless capacitor in parallel with the inverter bridge legs. All the active power switches in the full-bridge inverter arms and DC busline can achieve ZVS/ZVT turn-off and ZCS turn-on commutation operation. Therefore, the total switching losses at turn-off and turn-on switching transitions of these power semiconductor devices can be reduced even in the high switching frequency bands ranging from 20 kHz to 100 kHz. The switching frequency of this DC-DC power converter using IGBT power modules is selected to be 60 kHz. It is proved experimentally by the power loss analysis that the more the switching frequency increases, the more the proposed DC-DC converter can achieve high performance, lighter in weight, lower power losses and miniaturization in size as compared to the conventional hard switching one. The principle of operation, operation modes, practical and inherent effectiveness of this novel DC-DC power converter topology is proved for a low voltage and large current DC-DC power supplies of arc welder applications in industry.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.426-428
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• 1994

The effect of the snubber circuit is to control the voltage spikes applied across switching devices during turn-off. This paper describes a loss-less snubber of a converter for Switched Reluctance Motors. The feasibility of the snubber circuitry is experimentally verified using a laboratory prototype.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.114-117
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• 1999

This paper has described about principle and form of proposed circuit made use of soft switching technology ZVS(Zero-Voltage-Switching) to reduce turn on and off loss at switching. Also, the analysis of the proposed circuit was described by using normalized parameter and operating characteristics has been evaluated as to switching frequency and parameters. Based on the characteristics value, a method of the circuit design is proposed. The theoretical results are in good agreement with the experimental ones. The proposed circuit is considerated to be useful for induction heating and discharge lamp.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.189-194
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• 1999

This paper proposes a current-fed type high frequency inverter using a soft switching technology Zero-Voltage-Switching to reduce turn on and off loss at the switching. The analysis of the proposed circuit was described by using normalized parameter and operating characteristics have been evaluated as to switching frequency and parameters. The theoretical results are in good agreement with the experimental ones. In the future the proposed circuit is considered to be useful for induction heating applications.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.14-19
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• 1998

This paper has described about principle and form of proposed circuit made use of soft switching technology ZVS(Zero-Voltage-Switching) to reduce turn on and off loss at switching. also, the analysis of the proposed circuit has described by using normalized parameter and operating characteristics have been evaluated as to switching frequency and parameters. In addition, this paper proves the propriety of theoretical analysis in terms of the experiments.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1853-1859
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• 2008

IGBT modules are designed for low loss, rugged for all environments and user friendly. Low on state saturation voltage with high switching speed is the primary concerns. In this paper selection of IGBT, module ratings and characteristics are discussed. The IGBT design topic of protection against over voltage and over current are covered. Emphasis on turn off switching, short circuit switching and necessary precautions are dealt. Selection of IGBT device, gate drive power, and its lay out considerations are covered in detail.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.686-694
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• 2014

A power semiconductor device, usually used as a switch or rectifier, is very significant in the modern power industry. The power semiconductor, in terms of its physical properties, requires a high breakdown voltage to turn off, a low on-state resistance to reduce static loss, and a fast switching speed to reduce dynamic loss. Among those parameters, the breakdown voltage and on-state resistance rely on the doping concentration of the drift region in the power semiconductor, this effect can be more important for a higher voltage device. Although the low doping concentration in the drift region increases the breakdown voltage, the on-state resistance that is increased along with it makes the static loss characteristic deteriorate. On the other hand, although the high doping concentration in the drift region reduces on-state resistance, the breakdown voltage is decreased, which limits the scope of its applications. This addresses the fact that breakdown voltage and on-state resistance are in a trade-off relationship with a parameter of the doping concentration in the drift region. Such a trade-off relationship is a hindrance to the development of power semiconductor devices that have idealistic characteristics. In this study, a novel structure is proposed for the Insulated Gate Bipolar Transistor (IGBT) device that uses conductivity modulation, which makes it possible to increase the breakdown voltage without changing the on-state resistance through use of a P-floating layer. More specifically in the proposed IGBT structure, a P-floating layer was inserted into the drift region, which results in an alleviation of the trade-off relationship between the on-state resistance and the breakdown voltage. The increase of breakdown voltage in the proposed IGBT structure has been analyzed both theoretically and through simulations, and it is verified through measurement of actual samples.