• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 추계학술대회
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• pp.101-102
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• 2017

This paper presents analysis of losses of switching device for full bridge inverter connected to grid. The losses are a dominant factor that judges efficiency of the system. The losses of switching device are divided to switching loss and conduction loss. They are can be estimated by analyzing periodic switching waveforms. The switching loss is generated at the point that turn-on and off. And the conduction loss is generated while the switch is on condition. The estimated losses of switch are compared to simulation result in this paper.

• Journal of Power Electronics
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• 제19권1호
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• pp.68-78
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• 2019

The emergence of high voltage conversion applications has resulted in a trend of using semiconductor device series associations. Series associations allow for operation at blocking voltages, which are higher than the nominal voltage for each of the semiconductor devices. The main challenge with these topologies is finding a way to guarantee the voltage balance between devices in both blocking and switching transients. Most of the methods that have been proposed to mitigate static and dynamic voltage unbalances result in increased losses within the device. This paper introduces a new series stack topology, where the voltage unbalances are reduced. This in turn, mitigates the switching losses. The proposed topology consists of a circuit that ensures the soft switching of each device, and one auxiliary circuit that allows for switching energy recovery. The principle for the topology operation is presented and experimental tests are performed for two modules. The topology performs excellently for switching transients on each of the devices. The voltage static unbalances were limited to 10%, while the activation/deactivation delay introduced by the lower module IGBT driver takes place in the dynamic unbalances. Thus, the switching losses are reduced by 40%, when compared to hard switching configurations.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.115-120
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• 2003

In a motor driving, the current rate is directly related to the rate of a switching device and in cost reduction, the parallel switching operation is the alternatives because it has the smaller current rate through current division. There are many investigations for the parallel switching operations to equaling the current division. However it remains many problems for practical usage. The reason is that the switching characteristics are mainly relied on the different saturation voltage of each device etc. and these factors are not altered by circuit designer. In order to compensate this problem, a proper resistance is experimently inserted to the switching device. But this method can not be the optimal solution. Therefore this paper proposes a new parallel operation which uses a parallel phase winding to remove the traditional effect of switching device such as saturation voltage according to the division of current. Also the reliable and stable driving is improved through experiments and the detailed principles.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.24-28
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• 2002

In a motor driving, the current rate is directly related to the rate of a switching device and in cost reduction, the parallel switching operation is the alternatives because it has the smaller current rate through current division. There are many investigations for the parallel switching operations to equaling the current division. However it remains many problems for practical usage. The reason is that the switching characteristics are mainly relied on the different saturation voltage of each device etc. and these factors are not altered by a circuit designer. In order to compensate this problem, a proper resistance is experimently inserted to the switching device. But this method can not be the optimal solution. Therefore this paper proposes a new parallel operation which uses a parallel phase winding to remove the traditional effect of switching device such as saturation voltage according to the division of current. Also the reliable and stable driving is improved through experiments and the detailed principles.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
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• pp.141-148
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• 2002

In a motor driving, the current rate is directly related to the rate of a switching device and in cost reduction, the parallel switching operation is the alternatives because it has the smaller current rate through current division. There are many investigations for the parallel switching operations to equaling the current division. However it remains many problems for practical usage. The reason is that the switching characteristics are mainly relied on the different saturation voltage of each device etc. and these factors are not altered by circuit designer. In order to compensate this problem, a proper resistance is experimently inserted to the switching device. But this method can not be the optimal solution. Therefore this paper proposes a new parallel operation which uses a parallel phase winding to remove the traditional effect of switching device such as saturation voltage according to the division of current. Also the reliable and stable driving is improved through experiments and the detailed principles.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.563-565
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• 2004

It is expected to reduce stresses to components of high voltage circuit breaker and transferred switching surge from power system by applying controlled switching technique to high voltage system. This technique has at ready been applied in advanced countries. In this paper, basic principle of controlled switching technique is set up and a device to realize this technique is under developing. Controlled switching device will be improved by applying a method minimizing errors of operating time and by adopting compensation function relative to changes of ambient/operating condition.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 추계학술대회 논문집(Proceeding of the KOSME 2001 Autumn Annual Meeting)
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• pp.120-124
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• 2001

A new technique for improving the efficiency of single-phase high-frequency boost converter is proposed. This converter includes an additional low-frequency boost converter which is connected to the main high-frequency switching device in parallel. The additional converter is controlled at lower frequency. Most of the current flows in the low-frequency switch and so, high-frequency switching loss is greatly reduced accordingly Both switching device are controlled by a simple method; each controller consists of a one-shot multivibrator, a comparator and an AND gate. The converter works cooperatively in high efficiency and acts as if it were a conventional high-frequency boost converter with one switching device. The proposed method is verified by simulation. This paper describes the converter configuration and design, and discusses the steady-state performance concerning the switching loss reduction and efficiency improvement.

• Applied Science and Convergence Technology
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• 제24권6호
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• pp.278-283
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• 2015

In this work, the electrical bistability of an organic CT complex is demonstrated and the possible switching mechanism is proposed. 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and tetracyanoquinodimethane (TCNQ) are used as an organic donor and acceptor, respectively, and poly-methamethylacrylate (PMMA) is used as a polymeric matrix for spin-coating. A device with the Al/($Al_2O_3$)/PMMA:BCP:TCNQ[1:1:0.5 wt%]/Al configuration demonstrated bistable and switching characteristics similar to Ovshinsky switching with a low threshold voltage and a high ON/OFF ratio. An analysis of the current-voltage curves of the device suggested that electrical switching took place due to the charge transfer mechanism.

• Journal of Power Electronics
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• 제17권4호
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• pp.860-873
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• 2017

The present article reports an analysis and investigation of a direct AC-AC quasi-resonant converter. A bidirectional power device, whose switching frequency is lower than the frequency of the current passing through the load, is used for its realization. The zero voltage switching mode is described when zero voltage on the power device is available by measuring it with the control system. The continuous current in the resonant inductance by switching the power device at zero voltage is considered, and it is characterized by two sub-modes. A mathematical analysis of the processes has been made and comparative results from the computer simulation and experimental study have been brought. The converter can be used in a wide areas of power electronics: induction heating, wireless power transfer, AC-DC converters, etc.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.423-424
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• 2012