• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1244-1246
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• 2003

Conventional Switched Mode Power Supplies(SMPS) with diode-capacitor rectifier have distorted input current waveform with high harmonic content. Typically, these SMPS have a power factor lower than 0.65. To improve with this problem. the power factor correction(PFC) circuit of power supplies has to be introduced. Specially, to reduce size and manufacture cost of power conversion device, the single-stage PFC converter is increased to demand as necessary of study. In this case single-stage PFC converter has been used DC-DC converter with boost converter. However in this paper, it is studied flyback converter of high power factor, high efficiency by feedforward control. Also, the validity of designed and manufactured high power factor flyback converter is confirmed by simulation and experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.384-387
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• 2000

In this paper Power factor correction circuit of single-phase three-level boost converter is proposed. The advantage of the proposed control scheme for three-level boost converter are low blocking voltage of each power device low THD(Total Harmonic Distortion) and high power factor. The control scheme is based on the current comparator capacitor compensator and region detector, In simulations the proposed system is validated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.196-198
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• 2003

The low load power factor causes various problems such as the increase of the power loss and the voltage instability. The demand of reactive power increases continuously with the growth of active power and the restructuring of electric power companies makes the integrated management of ractive power troublesome, from which the systematic control of load power factor is required. In this paper, the load power factor sensitivity of the generation cost is derived and its effects in supplying the reactive power and enhancing the load power factor are analyzed in a small-scale power system. The load power factor sensitivity of the generation cost is applied for determining the locations and capacities of reactive power compensation devices. It is shown that the generation cost can be reduced and the system power factor can be enhanced effectively using the load power factor sensitivity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.153-155
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• 2004

Various problems such as the increase of the power loss and the voltage instability may often occur in the case of low load power factor. The demand of reactive power increases continuously with the growth of active power and the restructuring of electric power companies makes the integrated management of ractive power a troublesome problem, so that the systematic control of load power factor is required. In this paper, the load power factor sensitivity of the generation cost is used for determining the locations of reactive power compensation devices effectively and for enhancing the load power factor appropriately. In addition, the integrated costs are used for determining the value of the load power factor from the point of view of the economic operation. It is shown through the application to a large-scale power system that the system power factor can be enhanced effectively and appropriately using the load power factor sensitivity and integrated costs.

• 전기학회논문지
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• 제60권11호
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• pp.2109-2118
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• 2011

The power system has to maintain its synchronism from transient disturbances and oscillations. To achieve this, the static var compensator(SVC), which is a flexible AC transmission system(FACTS), is applied to the power system. SVC using an advanced control algorithm improves the stability of power system. This paper is a study on design of SVC to improve harmonics and power factor of power plant. The proposed SVC analyzes harmonics, voltage drop and reactive power in real time. On the basis of the analysis of the data, the SVC using a switching control algorithm decreases harmonic signals and increases the power factor. The experimental results show that the proposed SVC enhances the stability of power system.

• 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.

• 한국조명전기설비학회지:조명전기설비
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• 제5권2호
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• pp.84-95
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• 1991

Mostly, phase control method is used to control the single phase AC power. The phase control method has some advantages such as ease to control and simple configuration. But the retardation of firing angle causes a lagging current even if load is purely resistive. So phase control causes a lagging power factor and a low efficiency at the input side in comparing with the system without switching device. A new PWM control method which can improve these defects for single phase AC power control circuit is proposed in this paper. The performances of the single phase AC power control circuit using the proposed method was investigated theoretically. Both power factor and waveform of load current can be improved better than those of the conventional methods.

• Journal of Power Electronics
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• 제9권6호
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• pp.903-910
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• 2009

In this paper, a digital average current mode control using diode current sensing technique is proposed. Although the conventional inductor current sensing technique is widely used, the sensed signal of the current is negative. As a result, it requires an additional circuit to be applied to general digital controller ICs. The proposed diode current sensing method not only minimizes the peripheral circuit around the digital IC but also consumes less power to sense current information than the inductor current sensing method. The feasibility of the proposed technique is verified by experiments using a 500W power factor correction (PFC) boost rectifier.

• 전기학회논문지P
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• 제63권4호
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• pp.248-253
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• 2014

Generally, power factor correction (PFC) techniques play an important role in the power supply technology. Many new circuit topologies and control strategies for PFC have been proposed. Among them, the brideless PFC (BPFC) reduces the number of switching devices and the losses and improves the power density as well. Moreover, by implementing the improved topology in the discontinous conduction mode (DCM) it ensures almost unity power factor in a simple and effective manner. In the DCM operation gives additional advantages such as zero-current turn-on in the power switches, zero-current turn-off in the output diode and reduces the complexity of the control circuitry. In this paper, a new control strategy for the BPFC is proposed. Also, the performance of the proposed system is demonstrated through experiments.

• Journal of Power Electronics
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• 제7권3호
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• pp.203-212
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• 2007

In this paper, a proposed approach to improve the power factor of three-phase rectifiers and to stabilize the output voltage against load change is presented. The elements of the given control strategy are small size, low cost, high performance, and simplicity. The proposed control strategy of switches is based on a prototype of three bi-directional switched consisting of four diodes and one IGBT. A control technique and operational procedure are also developed, both theoretically and experimentally. The experimental results clearly verify the theoretical analysis from the prototype connected to grid unity.