• Journal of Power Electronics
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• 제9권1호
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• pp.18-25
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• 2009

Conventional series-resonant pulse frequency modulation controlled DC-DC high power converters with a high-frequency transformer link which is designed for driving the high power microwave generator has the problem of hard switching commutation at turn-on and turn-off of active power switching devices. This problem is due to the influence of the magnetizing current of the high-frequency transformer. This paper presents a novel prototype for a high-frequency transformer using parasitic parameters with a lossless inductive snubber and a series resonant capacitor assisted series-resonant zero current switching pulse frequency modulated DC-DC power converter, which is designed using a high power magnetron for microwave ovens. In order to implement a complete and efficient soft switching commutation, the performance of the new converter topology is practically confirmed and evaluated in the prototype of a power microwave generator.

• 전자통신동향분석
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• 제38권5호
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• pp.12-22
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• 2023

The development of neural networks is evolving towards the adoption of transformer structures with attention modules. Hence, active research focused on extending the concept of lightweight neural network algorithms and hardware acceleration is being conducted for the transition from conventional convolutional neural networks to transformer-based networks. We present a survey of state-of-the-art research on lightweight neural network algorithms and hardware architectures to reduce memory usage and accelerate both inference and training. To describe the corresponding trends, we review recent studies on token pruning, quantization, and architecture tuning for the vision transformer. In addition, we present a hardware architecture that incorporates lightweight algorithms into artificial intelligence processors to accelerate processing.

• Journal of Electrical Engineering and Technology
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• 제1권3호
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• pp.376-380
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• 2006

Temperature distribution measured to estimate the condition of an electrical apparatus is an absolute reference for the apparatus conditions and the difference between the reference temperature and the current temperature. Because of passive thermography, without the external thermal stimulation, the difference in surface temperature between the region of interest and back ground shows that the results can apply only to the estimation or the monitoring for the condition of loose terminal and the overload pertaining to the rise in temperature. However, a thermal diffusion in the active thermography is differently generated by the structure and condition of the surface and subsurface. This paper presents a nondestructive test using this behavior and deals with the results by heat injection and cooling to the apparatus. The buried discontinuity of subsurface could be detected by these techniques.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2020-2022
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• 1997

An active clamp forward converter is proper for minimization and basically makes high efficiency of the system because of soft switching type. Especially, when applied to forward converter, it widens the control range of duty ratio and is suitable for high input voltage. In other hand, the current doubler has high utility efficiency of transformer and reduces output current ripple because it always transfers the power through the transformer and has two inductor with opposite slope. So, this paper explained the conduction mode of an active clamp forward converter with the current doubler rectifier.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.369-371
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• 2006

Conventional active-clamp forward converter has narrow ZVS range of main switch. Although utilizing high magnetizing current can realize wide ZVS range, it increases the conduction loss. To solve this problem, a new asymmetric two-transformer active clamp forward converter is proposed. Proposed converter achieves wide ZVS range without severe conduction loss penalty, which results in high efficiency and high power density.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.13-14
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• 2010

The active clamp forward converter provides zero voltage switching and low voltage stress in wide input voltage range. It has a high efficiency at a high switching frequency and the clamped energy is recovered to the input stage. It is available for the power adaptor circuit of notebook computer. The adaptor with 19.5V/200W output power is designed for notebook computer. Specially, it is considered the transformer properties of the converter in design process. The organized process is checked by the validity from the test of the active clamp forward converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 추계학술대회
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• pp.190-191
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• 2010

In this paper, an analysis for leakage inductance of transformer in active clamped flyback inverter is presented. In the active clamp circuit of flyback inverter, the leakage inductance influences on the voltage across the primary switch and the resonant capacitor. Therefore, it is essential to optimize the leakage inductance design. In order to verify the theoretical analysis for the leakage inductance, PSIM simulation is used.

• 전력전자학회논문지
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• 제27권2호
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• pp.157-164
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• 2022

This study proposes an enhanced quadruple-Active-Bridge (QAB) converter that can solve power coupling problems. By adopting a multiple winding transformer, the equivalent circuit of a conventional QAB converter has power couplings between arbitrary output ports. This coupling is an unintended power relationship that complicates the regulation of output voltage of the multiple ports. The proposed converter can carry out power decoupling by changing the arrangement of the coupling inductor. Power transfer equations for the proposed converter and its operating principles are analyzed in detail. The power coupling caused by the transformer's leakage inductance is verified by using a proposed coupling factor that presents the relationship between inductance ratio and coupling power. In addition, the decoupling power control performance of the proposed converter is verified by simulation and a 3 kW prototype converter.

• E2M - 전기 전자와 첨단 소재
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• 제10권7호
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• pp.719-726
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• 1997

This research was conducted to analyze the change of surface tension, viscosity, streaming current and conductivity of transformer oil when it were injected with the interface active substances.(anionic:S-111, cationic:S-121, amphoteric:S-131) The changes properties of the surface tension and viscosity of the oil which were injected with the interface active substances were divided into the changes area and the minimum reduction area. The surface tension and viscosity of the oil which were injected with three different kinds of interface active substances showed remarkable change at the point where the concentration of the substance in anionic, in cationic and in amphoteric were 100[ppm], 10[ppm] and 1[ppm] respectively. The streaming current and conductivity of the same sample oil were also changed at the same densities of the surface tension and viscosity. For this factor, it was possibile for us to interpret the mechanism of the streaming current and conductivity. Therefore the interface active substances of the three kinds were injected into the oil within the limit of optimal volume, prevention effects of electrification were showed more excellence than unmixed insulating oil.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2629-2632
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• 2003

This paper presents the harmonics rejection technique and the simulation of a active power filter using power operational amplifier. The proposed active power filter consists of CT(current transformer), harmonics detector and harmonics amplifier. The harmonics detector is a high pass filter using a GIC(Generalized Impedance Converter). The harmonics amplifier consists of a power operational amplifier and passive filters. The simulation has been implemented by OR-CAD program. It is examined whether the proposed active power filter can be realized or not through simple experiments.