• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1051_1052
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• 2009

This paper deals with operational characteristic analysis of a single-phase PCS (Power Conditioning System) for PV (Photovoltaic) power generation system with AF (Active Filter) function. The theory of dq transformation has been applied to the control strategy of a single-phase PV power generation system to implement the AF function. Application of the virtual two-phase using phase-shift makes it possible to use the dq theory for the single-phase PV power generation system. The authors are sure that the proposed system is a very useful to compensate harmonics caused by nonlinear loads in a single-phase utility system. In this paper, not only a theoretical aspect of the single-phase PV-AF system is discussed, but also the DSP (Digital Signal Processor) based experiment results are presented to demonstrate the effectiveness of the single-phase PV-AF system.

• 전기학회논문지P
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• 제66권3호
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• pp.99-104
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• 2017

The three-phase four-wire power distribution system can be used to supply power to single-phase and three-phase loads at the same time. There are linear loads and nonlinear loads as single-phase loads connected to each phase. The nonlinear load generates a harmonic current during the power energy conversion process. In particular, the single-phase nonlinear load has a higher proportion of generation of the third harmonic current than the harmonics of the other orders. In a three-phase four-wire system, the third harmonic current flows through the neutral wire to the power supply side, affecting the power supply side and the line. Furthermore, the magnitude of the current flowing in the neutral line can be higher than the current flowing in the individual phase. If the neutral current is higher than the phase current, the breaker may be blocked. Therefore, it is necessary to reduce the amount of current flowing in the neutral line by harmonics. There is a method of zigzag connecting a single phase transformer by a method of reducing 3 harmonic current. In this study, the method of reducing the magnitude of the three harmonic currents flowing through the zigzag wire by comparing the polarity and the negative polarity characteristics of the single phase transformer was compared through measurement and simulation.

• 전기의세계
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• 제21권3호
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• pp.7-18
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• 1972

An analysis is made for the performance of twin stator single-phase induction machine having any movable asymmetrical angle of stator windings, with any symmetrical or asymmetrical magnetizing reactance and winding turn-ratio between two stators, provided that asymmetrical common squirrel cage rotor is utilized. This mechanism is a new type, which has the advantage of mading only not the performance prediction in applications as a single-phase electromagnetic driving mechanism but also the analysis prediction of single-phase induction motor with not in quadrature axis. The basis of the analyses are lead by Kron's primitive machine matrix and Morrill's double-revolving field concept. All the performances can be calculated from the test values and design details of the asymmetrical magnetizing reactance twin stator single-phase induction machine and verified by test. And its validity is still demonstrated to the pure twin stator single-phase induction machine.

• 설비공학논문집
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• 제12권4호
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• pp.422-429
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• 2000

Plate and shell heat exchanger(P&SHE) is widely applied as evaporators or condensers in the refrigeration and air conditioning systems for their high efficiency and compactness. In order to set up the database for the design of the P&SHE, heat transfer and pressure drop characteristics for single phase flow of water in a plate & shell heat exchanger are experimentally investigated in this study. Single phase heat transfer coefficients were measured for turbulent water flow in a plate and shell heat exchangers by Wilson plot method. The shell side heat transfer resistance was varied and the overall heat transfer coefficients were measured. The single-phase heat transfer coefficients in a plate side were obtained by Wilson plot method. Single-phase heat transfer correlations based on projected heat transfer area and friction factor correlations have been proposed for single phase flow in a plate and shell heat exchanger.

• 전기학회논문지
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• 제58권3호
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• pp.523-530
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• 2009

This paper presents a study on a small scale single-phase UPFC preliminary researches on power quality compensating schemes of electrical railway. As the UPFC is very complicated power-electronic system consisting of grid-connected transformers, four single phase inverters interconnected with dc-link capacitors and various electrical apparatuses, multiple controllers and control algorithms are needed, and entire UPFC has been modelled in the form of block diagrams and simulated by using Simulink. The main purpose of the compensating system is to manage reactive and active powers with the four single phase inverters, so, the control effort has been focused on the power flow control and has been realized through the hysteresis current control of the single phase inverters. And transport-delayed PLL with additional delay-time compensating term has been used to synchronize a grid voltage and the simulation results have shown that the compensating term could improve PLL performance under some frequency variation of the voltage.

• Journal of Power Electronics
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• 제16권2호
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• pp.498-511
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• 2016

This paper presents a single-phase five-level inverter controlled by two novel pulse width modulation (PWM) switching techniques. The proposed PWM techniques are designed based on minimum switching power loss and minimum total harmonic distortion (THD). In a single-phase five-level inverter employing six switches, the first proposed PWM technique requires four switches to operate at switching frequency and two other switches to operate at line frequency. The second proposed PWM technique requires only two switches to operate at switching frequency and the rest of the switches to operate at line frequency. Compared with conventional PWM techniques for single-phase five-level inverters, the proposed PWM techniques offer high efficiency and low harmonic components in the output voltage. The validity of the proposed PWM switching techniques in controlling single-phase five-level inverters to regulate load voltage is verified experimentally using a 100 V, 500 W laboratory prototype controlled by dspace 1103.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권8호
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• pp.377-386
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• 2005

This paper presents the control algorithm of single-phase hybrid active power filter for the compensation of harmonic current components in nonlinear R-L load with passive active Power filters. To construct two phase system, an imaginary second phase was made. In this proposed method, the new signal which is the delayed through the filtering by the phase-delay property of low-pass filter is used as the secondary phase. Because two-phases have the different phase, the instantaneous calculation of harmonic current is possible. In this paper, a reference voltage is created by multiplying the coefficient k by the compensation current using the rotating reference frame synchronized with the source-frequency, not applying to instantaneous reactive power theory which has been used with the existing fixed reference frames In order to verify the validities of the proposed control methods, experiments are carried out with the prototypes of single-phase hybrid active power filter.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권6호
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• pp.262-270
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• 2003

In this paper, the characteristics of single-phase line-start permanent magnet synchronous motor driven by constant voltage are analyzed on d-q axis vector diagram and compared with that of current controlled motor. The coupled method of symmetrical coordinates and d-q axis voltage equation are applied to the analysis method like the analysis of single-phase induction motor. From the result of the analysis, it is seen that motors driven by constant voltage source have effects on not only the amplitude of current and torque but also current and current phase angle, so overall characteristics such as power factor and load angle are affected by circuit parameters. For precise analysis and design of single-phase line-start synchronous motor, its characteristics should be analyzed on d-q axis vector plan in consideration of the variation of circuit parameters.

• 전기학회논문지P
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• 제57권2호
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• pp.170-175
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• 2008

This paper describes the exact short-circuit current calculation technique for the single-phase transformer which is installed in the three-phase systems and shorted in the secondary side. Not only the results for a short-circuit current calculation in the existing literatures are wrong, but also little literature deals with the short-circuit current for a single-phase transformer. So, this paper presents a theoretical study and calculation method for a single-phase short current. The validity of the presented method is investigated through Simulation using "Power Tools" and "PSim" program.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.135-140
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• 1997

A highly efficient single-phase/three-phase compatible ac-to-dc converter is proposed and analyzed, which includes three identical single-phase both soft-switched dc-to-dc converter with boost converter as a pre-regulator for input power factor correction (PFC). The proposed converter structure provides a cost reduction and easy implementation of compatibility between single-phase 220V and three-phase 220V/380V with their inputs in delta or wye connections.