• Journal of Magnetics
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• v.17 no.1
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• pp.36-41
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• 2012

The transcranial magnetic stimulation recharges the energy storing condenser, and sends the stored energy in the condenser to the pulse shaping circuit, which then delivers it to the stimulating coil. The previous types of transcranial magnetic stimulation required a booster transformer, secondary rectifier for high voltages and a condenser for smooth type. The energy storing condenser is recharged by switching the high-voltage direct current power. Loss occurs due to the resistance in the recharging circuit, and the single-pulse output energy in the transcranial magnetic stimulation can be changed because the recharging voltage cannot be adjusted. In this study a booster transformer, which decreases the volume and weight, was not used. Instead, a current resonance inverter was applied to cut down the switching loss. A transcranial magnetic stimulation, which can simultaneously alter the recharging voltage and pulse repeats, was used to examine the output characteristics.

• Journal of Power Electronics
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• v.19 no.6
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• pp.1366-1379
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• 2019

High-gain DC/DC converters have become one of the key technologies for the grid-connected operation of new energy power generation, and its research provides a significant impetus for the rapid development of new energy power generation. Inspired by the transformer effect and the ripple-suppressed ability of a coupled inductor, a double-coupled inductor high gain DC/DC converter with a ripple absorption circuit is proposed in this paper. By integrating the diode-capacitor voltage multiplying unit into the quadratic Boost converter and assembling the independent inductor into the magnetic core of structure coupled inductors, the adjustable range of the voltage gain can be effectively extended and the limit on duty ratio can be avoided. In addition, the volume of the magnetic element can be reduced. Very small ripples of input current can be obtained by the ripple absorption circuit, which is composed of an auxiliary inductor and a capacitor. The leakage inductance loss can be recovered to the load in a switching period, and the switching-off voltage spikes caused by leakage inductance can be suppressed by absorption in the diode-capacitor voltage multiplying unit. On the basis of the theoretical analysis, the feasibility of the proposed converter is verified by test results obtained by simulations and an experimental prototype.

• 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.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.2
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• pp.8-18
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• 1997

In this paper, a New Low Loss Quasi-Parallel Resonant DC-Link(NLQPRDCL) Inverter which shows highly improved PWM capability, low loss characteristic and low voltage stress is presented. A method to minimize freewheeling interval, which is able to largely decrease DC-link operation losses and to steadily guarantee soft switching in the wide operation region is also proposed. In addition, lossless control of zero voltage duration of DC-link makes the proposed inverter maintain the advanced PWM capability even under a very low modulation index. Experiment and simulation were performed to verify validity of the proposed inverter topology.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.4
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• pp.60-67
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• 2008

This paper presents a new full-bridge soft switching PWM DC-DC converter circuit topology that adding two switcher, two lossless snubber quasi-resonance capacity, two diode to power source for general welding machine. This half bridge soft switching Is low voltage hight current output that first coil current is smaller than second coil current in high frequency transformer can be obtained with decreasing path loss in conventional DC bus line switcher. As it operate ZCS/ZVS in full range, high frequency, high efficiency and high output are implemented at low voltage and high DC current switching power supplies. All of this items are got from simulation and the result of experiment. If make up for the weak points of this proposed circuit, it will be used more easily for next generation TIG, MIG and MAG type of arc-welding machine.

• Journal of IKEEE
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• v.25 no.2
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• pp.350-355
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• 2021

IGBT is a power semiconductor device that contains both MOSFET and BJT structures, and it has fast switching speed of MOSFET, high breakdown voltage and high current of BJT characteristics. IGBT is a device that targets the requirements of an ideal power semiconductor device with high breakdown voltage, low V_CE-SAT, fast switching speed and high reliability. In this paper, we analyzed Gate oxide thickness, Trench Gate Width, and P+Emitter width, which are the top process parameters of 1,200V Trench Gate Field Stop IGBT, and suggested the optimized top process parameters. Using the Synopsys T-CAD Simulator, we designed IGBT devices with electrical characteristics that has breakdown voltage of 1,470 V, V_CE-SAT 2.17 V, Eon 0.361 mJ and Eoff 1.152 mJ.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.404-408
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• 2000

The novel control method of ZVS Full-bridge PWM converter with pulse load current is proposed. This new control method can reduce the switching loss of switches during no load condition. Moreover by using feed-forward load current information this method can obtain better transient dynamics compared to the system with only linear feedback control.

• 전기의세계
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• v.30 no.9
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• pp.582-588
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• 1981

The laser parameters such as a population inversion density, a stimulated emission cross section and loss factor in the glass laser amplifier medium were experimentally determined in order to analyse the properties of laser amplification. Using these parameters, the rate equations were approximately solved and the properties of laser amplification were analysed. An experiment of two-stage amplifier of Q-switching laser pulse was performed and the maximum output power was 1.1 GW, 33J. The several problems such as a laser solarization and a laser coupling in laser amplification were resolved.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.380-383
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• 1998

Amplitude Modulation PWM Technique which has characteristics such as the switching loss and Harmonic distortion reduction is compared in this paper. And also Harmonic components only carrier frequencies. And as it is showed Harmonic components only carrier frequencies via simulation results. Am-pwm is applied to the inverter system of High-speed induction motor.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.382-383
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• 2013

본 논문에서는 대용량 3상 전류형인버터의 효율향상을 위해 스위칭손실을 저감시킬 수 있는 3단계 스위칭시퀀스 기반 SVPWM 제어기법을 제안하고, 기존 SPWM 혹은 SVPWM 제어기법과 비교/검토하여 시뮬레이션 해석을 통해 유효성을 검증한다.