• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.629-632
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• 2009

We have proposed a novel viewing angle controllable display of in-plane switching (IPS) mode with single panel. One pixel of this device is divided to two regions, in which main pixel shows image and sub pixel for viewing angle control. In initial state, the liquid crystal of sub pixel is homogeneous aligned on substrate for wide viewing angle mode. On the other hand, after applying voltage, the liquid crystal of sub pixel tilts up for narrow viewing angle mode. The proposed device has advantage for the function for simple manufacturing process and good viewing angle control with single panel.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.54-59
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• 1996

As the current shape of SRM is of pulse type and changed by the motor parameters and drive conditions, the influences on the drive efficiency by control method are more than other types of motors. In this paper, a proper excitation condition to drive a SRM with high efficiency is proposed and tested. It is derived from the conditions that the phase current of a SRM is to be flat-topped at various drive. The saturation effect of magnetic circuit is accounted for more accurate analysis. Experimental tests are executed to verify the proposed excitation method. This drive system is easy to commutate and also advantageous in reducing torque ripple. (author). 6 refs., 10 figs., 1 tab.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.111-112
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• 2017

This paper presents a novel three-port converter for the OnBoard Charger of Electric Vehicles by using an impedance control network. The proposed concept is suitable for charging a main battery and an auxiliary battery of an electric vehicle at the same time due to its power handling capability of the converter without additional switches. The power flow is managed by the phase angle (${\Theta}$) between the ports whereas voltage at each port is controlled by the asymmetric duty cycle and the phase shift (${\Phi}$) between the inverter lags controlled by the impedance control network. The proposed system has a capability of achieving zero voltage switching (ZVS) and zero current switching (ZCS) at all the switches over the wide range of input voltage, output voltage and output power. The feasibility of the proposed system is verified by the PSIM simulation.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1067-1070
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• 1992

Optimal Asymmetrical Pulse-width Modulated (APWM) technique for ac chopper is proposed which can improve the input power factor and eliminate the harmonics of output voltage up to a specified order, and also enables linear control of the fundamental component of the output voltage. The PWM switching patterns at the specified phase angle are obtained by Newton-Raphson method and theoretical comparisons are made with other PWM and APWM technique.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.5
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• pp.41-50
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• 1995

Single-phase induction motors are widely used in many light duty applications, especially in home and office. many applications which use these motors require adjustable speed control continuously. In general, the speed control of single-phase induction motor is accomplished at a few discrete speeds by using tapped-windings, pole switching or gear. These techniques are inefficient and complicated. In this paper, Torque controller which adjusts a generating torque using phase difference between main winding voltage and auxiliary winding voltage is proposed. The analysis includes the determination of the relationship between the auxiliary winding voltage is proposed. The analysis includes the determination of the relationship between the auxiliary winding voltage phase angle and torque. Simulation results of the torque-speed characteristics using the controlled auxiliary winding supply are shown and discussed. and the drive is tested experimentally to verify the results of the theory by using a dynamometer.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.11
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• pp.128-139
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• 1999

This paper proposes a linearization technique for the space vector modulation method, which increases the linear control range of inverter up to the 6-step inverter. This method is based on fourier series expansion of the desired output voltage of the inverter to calculate the compensation angle in continuous switching mode and holding angle in discontinuous switching including the 6-step mode respectively. The approximation equation of these angles are used for compensation of fundamental voltage in overmodulation range. Therefore, it is possible to obtain the linear control and the maximized utilization of PWM inverter output voltage.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.492-494
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• 1996

This paper describes a study on the series resonant inverter using the double full-bridge, and the output voltage of the proposed inverter is controlled by phase shift angle of the outputs of two inverters. These control schemes can be reduce the switching loss and EMI, etc, which the inverter is drived by auto following control of output frequency, because it is impossible for switching devices to be always turned on and off at zero voltage or zero current. Theoretical characteristics of the proposed double inverter circuit are compared with Pspice simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.278-281
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• 2000

In this abstract a novel control scheme of voltage-source PWM rectifiers using only dc-side sensors is proposed. The phase currents are reconstructed from switching states of the rectifier and the dc output current. For effective current control the currents are estimated by a predictive state observer. Also both the phase angle and the magnitude of th source voltage are estimated by phase estimator and magnitude estimator respectively. The validity of the proposed ac sensorless technique is verified by experimental results.

• Journal of Power Electronics
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• v.11 no.5
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• pp.677-687
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• 2011

In this paper a cycloconverter-type high frequency transformer link inverter with a reduced switch count is analyzed and designed. The proposed topology consists of an H-bridge inverter at the transformer's primary side and a cycloconverter with three bidirectional switches at the secondary. All of the switches of the cycloconverter operate in non-resonant zero voltage and zero current switching modes. To overcome a high voltage surge problem resulting from the transformer leakage inductance, phase angle control based on natural commutation is employed. The effectiveness of the proposed inverter is verified by constructing s 750W prototype. Experimentally, the inverter is able to supply a near sinusoidal output voltage with a total harmonic distortion of less than 1%. For comparison, a PSpice simulation of the inverter is also carried out. It was found that the experimental results are in very close agreement with the simulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1356-1361
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• 2008

A switched reluctance generator(SRG) has simple magnetic structure, and needs simple power electronic driving circuit. But, a SRG are no windings or permanent magnets on the rotor, and there are concentrated windings placed around each salient pole on the stator. Because of the characteristics of time-sharing excitation, the control of SRG is very flexible. And there are several parameters for controlling SRG, such as switch turn-on angle, switch turn-off angle, and exciting voltage and controlling mode, all these will affect the generation greatly. A SRG has positive torque at increasing inductance region and negative torque at decreasing inductance region. In this paper, we studied characteristics about the switch turn-on and off angles according to switch method for constant output voltage of the fixed speed SRG. It is the acoustic noise and torque ripple characteristics. Characteristics for a switch angle and method are presented by experiment using a 50W SRG with 12/8 poles.