• Journal of Power Electronics
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• v.12 no.4
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• pp.587-594
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• 2012

When a PWM rectifier has a low DC-link voltage during startup, the output voltage vector cannot be high enough to regulate the input current. This lack of a PWM rectifier output voltage vector can cause an unregulated inrush current when the rectifier operation starts. This paper presents a PWM rectifier start-up current control algorithm for when it starts operation with a lower DC-link voltage than unloaded condition case. To avoid the unregulated inrush current caused by a lack of DC-link voltage, the proposed control scheme regulates the one phase current with one switch chopping and it generates the current command considering the uncontrolled current magnitude information, which is calculated in advance. Simulation and experiment results support the validity of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.179.6-179
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• 2001

This paper proposes the recognition method of the strip shape using the Least-Square method and the distinction method of the asymmetric shape and the compensation method upon the shape control values for the stainless steel cold rolling mill. This paper proposes the shape recognition method before control and the compensation method to minimize the fluctuation of the shape deviation and to get symmetric shape. This paper shows on line test results to verify the performance of the control method for the process. The experiments have been performed with respect to various material type, thickness, and strip width. The performance of the proposed method is obtained excellent quality and high productivity as results.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.2
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• pp.131-139
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• 1996

Inthis apper wa analyzed the channel-hot-electron programming characteristics of the single-poly EEPROM with different control gate and drain structures. The single-poly EEPROM uses the p$^{+}$/n$^{+}$-diffusion in the n-well as a control gate instead of the second poly-silicon. The program and erase characteristics of the single-poly EEPROM were verified using the two-dimensional device simulator, MEDICI. The single-poly EEPROM was fabricated using 0.8$\mu$m ASIC CMOS process, and its CHE programming characteristics were measured using HP4155 parameteric analyzer and HP8110 pulse gnerator. Especially we investigated the CHE programming characteristics of the single-poly EEPROM with the p$^{+}$-diffusion or n$^{+}$-diffusion in the n-well as a control gate and the LDD or single-drain structure. The single-poly EEPROM with p$^{+}$-diffusion in the n-well as a control gate and single-drain structure was programmed to about VT$\thickapprox$5V with VDS=6V, VCG=12V(1ms pulse width).th).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.3-9
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• 1999

The recent technical trend in hot rolling of steel can be described as process and product technologies which have been progressed with modern mill equipment and computers. Precise gauge and width control can be achieved by up-to-date control methods such as AGC and AWC systems. Roll benders and various shape control systems enabled high quality flatness and crown control. Mills can produce higher tensile materials by new process based on process metallurgy. The use of high speed steel rolls and on line roll grinders make the schedule free rolling easier which results in cost saving. Process itself goes toward continuous and simple flow type which has lower operation. Endless rolling and strip casting are examples of the trend. Materials with higher tensile strength and various functions have been developed in last years to meet the customer's needs and this trend will continue.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.10
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• pp.867-873
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• 2002

We have designed and fabricated the slidacs type automatic voltage regulator(SVR) that is able to control the output voltage continuously according to load variation. Especially, the frictions between the surface of contact of the slidacs coils and the output wire moving shaft arc reduced by modifying the mechanical configuration of surface of contact of slidacs from the conventional sliding one into the proposed rotary one composed of cylindrical bearing. Thus, SVR using cylindrical bearing proposed in this study has less noise than the conventional one owing to the reduction of friction, and its breakdown ratio caused by the abrasion of contact materials is reduced as well. We have designed U motor driving circuit for controlling the output wire moving shaft, and introduced the digital control method using the pulse width modulation(PWM) output for controlling DC motor.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.6
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• pp.842-846
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• 2016

This paper presents a DC-DC buck converter which uses a sleep control to improve the power efficiency in a few mW light load condition. The sleep control turns off analog controller building blocks to reduce the static power losses during the off-duty period of pulse width modulation. For verification, a buck converter has been implemented in a $0.18{\mu}m$ CMOS process. The power efficiency has been improved from 76.7% to 82.5% with a 1.2 mW load. The maximum power efficiency is 95% with a 9 mW load.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.245-248
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• 2008

This paper gives a description of the mode'ling and control of a single phase PWM(Pulse Width Modulation) converter for HEMU-400X(High-speed Electric Multiple Unit - 400 km/h experiment). The converter is part of a Auxiliary power unit supplied by the 25[kV], 60[Hz] overhead line. A model of the converter in a synchronously rotating reference frame of coordinates is used to develop a new type of control. The control system has separate controllers for the active and reactive current, permitting the free choice of the power factor. This paper proposes a new control method of PWM converter for Auxiliary power unit.

• Journal of Advanced Marine Engineering and Technology
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• v.11 no.2
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• pp.37-50
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• 1987

In an effort to conserve electric power, variable voltage variable frequency pulse width modulated (PWM) inverters are being applied increasingly to the variable speed control of the induction motors. The use of the PWM technique in motor drive applications is considered advantageous in many ways. For industrial applications, the PWM drive obtains its DC input through simple uncontrolled rectification of the commercial AC line and is favored for its good power factor, good efficiency, its relative freedom regulation problem, and mainly for its ability to operate the motor with nearly sinusoidal current waveforms. The purpose of this paper is to design a three phase natural sampled PWM inverter using microprocessor with simple control algorithm and hybrid control circuit has been built to implement this PWM scheme. In this system, the microprocessor can be used only for calculations directly related to motor control tasks by the design of hybrid circuit which sends PWM signals to the motor.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1144-1149
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• 2008

Converting technology has developed to print information for the decades. Recently, this technology (like gravure, gravure-offset) is rising as an alternative way for mass production of printed electronics such as RFID, solar cell. For the width of printing line is under 10 microns, registration error should be minimized less than several microns. Tension disturbance is main cause of registration error and this should be minimized before the substrate is transported into printing zone. With PI controller, it is possible to suppress the disturbance within 2% of operating tension. But register error appears more than 10 micron using PIcontroller considering noise. So LQG controller is needed as an alternative control method. In this paper, the comparision of PI and LQG controller in the converting machine including measured noise and tension disturbance is presented. It is shown that the LQG controller is more suitable for precision tension control in printed electronics.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.110-110
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• 2000

In this paper, an antilock brake system (ABS) for commercial vehicles is studied by considering the design of a fuzzy Logic controller with pulse width modulation (PWM). PWM method is used for generating solenoid valve inputs in order to cope with the chattering problem caused by the conventional on/off control The sliding mode observer is designed to estimate the vehicle longitudinal velocity and it is used to calculate the wheel slip ratio. The effectiveness of the proposed control algorithm was validated by simulations performed with a nonlinear 14-DOF vehicle model including the dynamics of the brakes.