• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2388-2390
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• 2002

Small type electric energy saving system is proposed in this paper. The system improves power factor fastly according to load variation of each customer. Phases of voltage and current are detected as 1[ms] unit. Phase coincident algorithm is applied for power factor improvement. Capacitance is controlled for optimal power factor correction. Series reactor is controlled for harmonics reduction. Non-contact device is used for fast response and long life. Test result shows the effect of this system. Power factor of 40[W] electric fan is improved from 95[%] to 100[%]. In the case of electric light, power factor is improved from 82[%] to 100[%]. Response time for load variation is less than 1[ms].

• Journal of Advanced Marine Engineering and Technology
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• 제29권7호
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• pp.744-749
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• 2005

This paper describes the performance improvement of power control system of magnetron (MGT) for microwave oven. The MGT is used extensively in household microwave oven and industrial microwave heating devices, and is operated by 3.0[kV] $\∼$5.0[kV] dc high voltage. The proposed power supply is consisted of a bridge rectifier, step-up converter(SUC) and its controller, half bridge inverter(HBI) and its controller, and full wave double voltage rectifier(DVR). In the proposed system, a good power factor can be obtained by the SUC' switching method that the inductor current waveforms follows that of the rectified voltage, and a line input power can be controlled to a range of 17.5[$\%$] by duty ratio (DR) adjustment of the HBI.

• 대한전기학회논문지:전력기술부문A
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• 제48권12호
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• pp.1507-1513
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• 1999

This paper describes simulation and experimental results to analyze the dynamic characteristics of STATCOM, which is connected to the ac system for compensation the power factor and improving the voltage stability. The simulation and experimental results confirm that the scaled model for STATCOM can properly compesate the power factor of the load and regulate the bus voltage at the common connection point.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.94-96
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• 1993

At an operating point of the induction motor, there are many sets of stator frequency and voltage. This paper presents an algorithm to determine the stator frequency and voltage which maximizes the power factor without any informations of motor parameters. Improvement of efficiency us also expected due to high-power-factor operation.

• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.951-958
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• 2013

This paper proposes the controller design for a stability improvement of an on-board battery charger. The system is comprised of a power factor correction (PFC) circuit and phase shift full-bridge DC-DC converter. The PFC circuit performs the control of the DC-link voltage and the input power factor. The DC-DC converter regulates the voltage and the current in the battery using the DC-link voltage. This paper proposes the design method of PI controller for the PFC circuit using a small signal model. The analysis and design of a type-three controller for the DC-DC converter is also presented. A simulation and experiment has been performed on the on-board battery charger and their results are presented to verify the validity of the proposed system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.902-904
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• 1996

In this paper, we proposed the reasonable design standard and countermeasures of Demand Factor for large office buildings, that was made by the statistical way considering actual conditions, such as investicated electric equipment capacity, electric power consumption, etc. So as to save electric equipment investment, the decrease of power loss, the improvement of facilities utilization and the decrease of electric rates, we can be contributed by the application of the design standard. The result of saving effect is showed to confirm the practical use of the proposed Demand Factor, and also, it is believed that this proposed Demand Factor will be useful in electric equipment operation and planning.

• 전기전자학회논문지
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• 제23권2호
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• pp.495-501
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• 2019

본 논문에서는 정류 브리지 다이오드를 갖는 단상 무정전전원장치의 전원측 고조파 및 역률 개선을 위한 가변형 고조파 필터를 제안한다. 2레벨 이상의 전력변환방식을 적용한 무정전전원장치는 전원측 고조파 및 역률 특성이 우수한 반면, 전 브리지 방식의 무정전전원장치는 전원측에 제 3고조파, 제 5고조파, 제 7고조파 및 역률 저하를 심각하게 야기한다. 이에 따라 단상 전 브리지 동작에 의해 야기된 (2n+1)차 고조파 제거 및 역률 개선을 위한 가변형 고조파 필터를 제안하고자 한다. 제안한 가변형 고조파 필터의 성능을 평가하기 위해 다양한 시뮬레이션과 실험을 진행하여 타당성을 검증하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.77-80
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• 2003

Switching Mode Power Supply(SMPS) is widely used in many industrial fields. Power factor improvement and harmonic reduction technique are very important in SMPS. In this paper, we propose the circuit applied Flying Capacitor Snubber for improving power factor of boost converter on fast switching state. Snubber circuit consists of a inductor, two diodes and a capacitor. The losses of switching are reduced by inserting a snubber inductor in the series path of the boost switch and the rectifier diode to control the di/dt rate of the rectifier during it's turn-off. Prior to actual experiment, the circuit analysis Is implemented by PSPICE simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.209-211
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• 2002

This paper computes the regional, seasonal and hourly representative model of load power factor considering load characteristics of all 154/22.9 kV substations. An accurately computed representative model of load power factor is studied to present a precision improvement of power system analysis and the security of the system. The method to compute representative model of load utilizes the method of applicable moving average based on the method of flow average. The EMS data are used as the source to assess the load power factor.

• 전기학회논문지P
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• 제57권1호
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• pp.36-40
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• 2008

Most of the low-voltage feeder are designed with approximately balanced and connected at the three phase four wire systems. However, Most of the power distribution systems' load which is composed of single or three phase are unbalanced by generating load unbalance. Unbalanced current will draw a highly unbalanced voltage. The power factor of an induction motor at rated operation is between 25 and 90%, depending on the size and speed of the motor. However, many induction motors operate below the nominal rating, resulting in poor power factor. This condition needs power factor improvement. Addition of power capacitor at the motor terminal may draw to stress due to voltage unbalance. This paper presents operation characteristics on steady states of a three-phase induction motor under unbalanced voltages with power capacitor. The existence of voltage unbalance have an effect on stress of power capacitor.