• 전력전자학회논문지
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• 제21권6호
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• pp.525-529
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• 2016

In the case of a motor system that converts electrical energy into mechanical energy, the region of the motor and that of the generator coexists. In the case of an escalator, the ascending escalator is operated by the motor, whereas the descending escalator is operated by the generator according to the load. To evaluate the proposed method, this study reduces the power of the ascending escalator up to approximately 35% by sharing the regeneration power of the descending escalator. The loss of transfer power nearly exists in the case of the proposed method. Furthermore, the lifetime of the DC link condenser can be extended because it is connected in parallel, thus leading to a twofold increase in capacity.

• 공학기술논문지
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• 제10권2호
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• pp.203-208
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• 2017

Due to global climate change issues, there is a growing demand for systems throughout the industry. In the case of power conversion, studies have been actively conducted to change the structure of the power conversion circuit and to apply new power devices. In particular, the WBG (Wide Band Gap), which is newly emerged device in the market for developing semiconductor technology, has demonstrated advantages in applying for various aspects in comparison to the existing Si (Silicon) Semiconductor. Recent research centers in the railway industry are focusing on developing technologies suitable for railway vehicles by utilizing these new developments in railway countries such as Japan and Europe. This paper researches the WBG device that is applicable to the auxiliary power supplies (APS) in railway system, and analyzes the downsizing effects to APS in high-speed railway by conducting a theoretical analysis and simulation.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 추계학술대회 논문집
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• pp.383-386
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• 2009

Contract power conversion factor which is applied to estimate contract power of industrial customers is an important standard to calculate transformer capacity. This paper shows a reasonable contract power conversion factor, that was made by the systematic and statistical way considering actual conditions, such as investigated contract power and peak power for the last 5 years of each customer for industrial customers as to AMR system. In this dissertation, it is necessary to analyze the key features and general trend from the investigated data. It made an analysis of the feature parameters, such as average, standard deviation, median, maximum. minimum and thus it was carried the linear and nonlinear regression analysis. Therefore, this paper compared characteristics for a contract power conversion factor which is applied to calculate contract power with characteristics for a regression model for customers which maximum utilization factor of transformer is more than 60%.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.293-296
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• 2008

Contract power conversion factor which is applied to estimate contract power of general customers IS an important standard to caculate transformer capacity. This paper shows a reasonable contract power conversion factor, that was made by the systematic and statistical way considering actual conditions, such as investigated contract power and peak power for the last 5 years of each customer for 132 office building customers as to AMR system. In this dissertation, it is necessary to analyze the key features and general trend from the investigated data. It made an analysis of the feature parameters, such as average, standard deviation, median, maximum, minimun and thus it was carried the linear and nonlinear regression analysis. Therefore, this paper compared characteristics for a contract power conversion factor which is applied to calculate contract power with characteristics for a regression model for customers which maximum utilization factor of transformer is more than 60%.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1756-1758
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• 2005

This paper deals with the power conversion and design of permanent magnet generator for wind power applications. This paper derives analytical solutions for open-circuit field, armature reaction field, torque, back-emf, inductance and resistance of permanent magnet generators for wind power applications. And then, by presenting the variation of torque according to design parameters and by applying restrict conditions to it, we determine proper design parameter appropriate to rated power and speed. Finally, this paper also presents power conversion system resonable in wind power applications.

• 산업기술연구
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• 제30권A호
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• pp.69-73
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• 2010

In this paper, we designed the RF-DC converter used in wireless power transmission system and studied how to design the RF-DC converter of high conversion efficiency. The RF-DC converter operate at 2.45GHz and the diode is connected with series. The RF-DC converter uses shorted stub for DC loop and matching. We can divide the RF-DC converter circuit into four blocks. The reflection coefficients between the blocks were optimized for the maximum conversion efficiency at 0 dBm input power and $1300{\Omega}$ load impedance. The final design of the RF-DC converter has a 52 percent conversion efficiency.

• 전기학회논문지
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• 제66권3호
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• pp.475-485
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• 2017

This paper develops a conversion function and method transforming from daily peak load curve used $LOLE_D$ [days/year] to hourly load curve used $LOLE_H$[hours/year]and describes relationship between $LOLE_D$ [days/year] and $LOLE_H$ [hours/year]. The indices can not only be transformed just arithmetically but also have different characteristics physically because of using their different load curves. The conversion function is formulated as variables of capacity and forced outage rate of generator, hourly load daily load factor and daily peak load yearly load factor, etc. Therefore, the conversion function (${\gamma}={\varphi}$(.)) can not be simple. In this study, therefore, the function is formulated as linear times of separated two functions. One is an exponential formed conversion function of daily load factor. Another is formulated with an exponential typed conversion function of daily peak load yearly load factor. Futhermore, this paper presents algorithm and flow chart for transforming from $LOLE_D$[days/year] to $LOLE_H$[hours/year]. The proposed conversion function is applied to sample system and actual KPS(Korea Power System) in 2015. The exponent coefficients of the conversion functions are assessed using proposed method. Finally, assessment errors using conversion function for case studies of sample system and actual system are evaluated to certify the firstly proposed method.

• 조명전기설비학회논문지
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• 제12권4호
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• pp.75-80
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• 1998

본 논문에서는 DSP 장치와 개인용 컴퓨터를 연계한 실시간 인버터 특성 분석 시스템을 제안하였다. 전력 변환 시스템은 제어 대상과 용도에 따라 회로를 셜계한다. 그리고 설계된 전력 변환 시스랩은 입력 조건에 따라 시스템의 제어특성이 평가된다. 따라서 제어방법을 연구하기 위해서는 전력 변환 시스템이 필요하고, 이를 평가하기 위한 관측 시스랩이 필요하다. 제안한 실시간 특성 분석 시스랩을 평가하기 위하여 인버터 시스템을 구성하였다. 그리고 개인용 컴퓨터를 이용하여 입력 제어 조건에 따라 유도전동기를 구동하였다. 이때 얻어지는 인버터 출력 특성 및 제어특성올 다양하게 분석하였다.

• Journal of Power Electronics
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• 제10권1호
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• pp.72-78
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• 2010

In this paper the operation of a double-fed wound-rotor induction machine, coupled to a wind turbine, as a generator at sub-synchronous speeds is investigated. A novel approach is used in the analysis, namely, the rotor power flow approach. The conditions necessary for operating the machine as a double-fed induction generator (DFIG) are deduced. Formulae describing the factors affecting the range of sub-synchronous speeds within which generation occurs are deduced. The variations in the magnitude and phase angle of the voltage injected to the rotor circuit as the speed of the machine changes to achieve generation at the widest possible sub-synchronous speed range is presented. Also, the effect of the rotor parameters on the generation range is presented. The analysis proved that the generation range could increase from sub-synchronous to super-synchronous speeds, which increases the amount of energy captured by the wind energy conversion system (WECS) as result of utilizing the power available in the wind at low wind speeds.

• IEIE Transactions on Smart Processing and Computing
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• 제5권5호
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• pp.349-357
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• 2016

The era of the Internet of Things (IoT) is upon us. In this era, minimizing power consumption becomes a primary concern for system-on-chip designers. While traditional power minimization and dynamic power management (DPM) techniques have been heavily explored to improve the power efficiency of devices inside very large-scale integration (VLSI) platforms, there is one critical factor that is often overlooked, which is the power conversion efficiency of a power delivery network (PDN). This paper is a tutorial that focuses on the power conversion efficiency of the PDN, and introduces novel methods to improve it. Circuit-, architecture-, and system-level approaches are presented to optimize PDN designs, while case studies for three different VSLI platforms validate the efficacy of the introduced approaches.