• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.847-853
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• 2010

This paper describes switching surge analysis for reclosing decision in 345kV combined transmission line with XLPE power cable. Reclosing operation should be decided based on the detailed technical analysis in combined transmission line because this line includes power cable section which is week on insulation. Insulation of power cable can be breakdown at the week point in case of reclosing moment. Therefore the detailed analysis has to be carried out by considering several conditions such as length ratio of power cable section, arrestor, inserting resistance, charging rate, grounding resistance, etc.. On the other hand sheath voltage on IJ(Insulated Joint) is analyzed to check dangerous condition on cable cover. Analysis is performed by EMTP/ATP. Analysis results show that reclosing can be operated as the single line-to-ground fault occurs on overhead line in 345kV combined transmission line, if the inserting resistance is considered before the operation of main circuit breaker.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.6
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• pp.632-641
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• 2008

This paper is concerned with the development of the piezoelectric energy harvesting(PEH) device for ubiquitous sensor node(USN). The USN needs auxiliary power to lengthen its operational life. In this study, the piezoelectric energy harvesting system consisting of a cantilever with a tip mass and piezoelectric wafer was investigated in detail both theoretically and experimentally. The dynamic model for the addressed system was derived using the assumed mode method. The resulting equations of motion were expressed in matrix form, which had never been developed before. The power output characteristics of the PEH was then calculated and discussed. Various experiments were carried out to investigate the charging characteristics of electrical components. Theoretical and experimental results showed that the PEH was able to charge a battery with ambient vibrations but still needed an effective mechanism which can convert mechanical energy to electrical energy and an optimal electric circuit which dissipates small energy.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.7
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• pp.513-518
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• 2016

The piezoelectric actuating device is known for its large power density and simple structure. It can generate a larger force than a conventional actuator and has also wide bandwidth with fast response in a compact size. To control the piezoelectric actuator, we need an analog signal conditioning circuit as well as digital microcontrollers. Conventional microcontrollers are not equipped with an analog part and need digital-to-analog converters, which makes the system bulky compared with the small size of piezoelectric devices. To overcome these weaknesses, we are developing a single-chip controller that can handle analog and digital signals simultaneously using mixed-signal FPGA technology. This gives more flexibility than traditional fixed-function microcontrollers, and the control speed can be increased greatly due to the parallel processing characteristics of the FPGA. In this paper, we developed a floating-point multiplier, PWM generator, 80-kHz power control loop, and 1-kHz position feedback control loop using a single mixed-signal FPGA. It takes only 50 ns for single floating-point multiplication. The PWM generator gives two outputs to control the charging and discharging of the high-voltage output capacitor. Through experimentation and simulation, it is demonstrated that the designed control loops work properly in a real environment.

• Journal of Magnetics
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• v.17 no.1
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• pp.27-32
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• 2012

Transcranial magnetic stimulation requires an electric field composed of dozens of V/m to achieve stimulation. The stimulation system is composed of a stimulation coil to form the electric field by charging and discharging a capacitor in order to save energy, thus requiring high-pressure kV. In particular, it is charged and discharged in capacitor to discharge through stimulation coil within a short period of time (hundreds of seconds) to generate current of numerous kA. A pulse-type magnetic field is formed, and eddy currents within the human body are triggered to achieve stimulation. Numerous pulse forms must be generated to initiate eddy currents for stimulating nerves. This study achieved high internal pressure, a high number of repetitions, and rapid switching of elements, and it implemented numerous control techniques via introduction of the half-bridge parallel load method. In addition it applied a quick, accurate, high-efficiency charge/discharge method for transcranial magnetic stimulation to substitute an inexpensive, readily available, commercial frequency condenser for a previously used, expensive, high-frequency condenser. Furthermore, the pulse repetition rate was altered to control energy density, and grafts compact, one-chip processor with simulation to stably control circuit motion and conduct research on motion and output characteristics.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1338-1339
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• 2008

In this paper, charging part by basic from Andrew's body model research to second a danger have affect on remaining and rehabilitation humans in space under water. The construction of a circuit make to Andrew's body model. It compare that voltages measure a hand, a breast, a groin and electric currents measure an arm, a breast, a leg with safety a limit of body through an electric current. Out of result, it research that magnitude and wave of body passing an electric current give the effect to the heart control a signal and it have affect on direct the ventricle of the heart in detail motion. A thing of this sort get through to the simulation by the ATP-Draw program. The results from above, it is publish one's research work with safety a limit electric angle take measurement of resistance a body in under water and to the voltage and electric current passing each parts.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.8
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• pp.90-97
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• 2014

This paper presents a compensation method of unbalanced phase currents in interleaved bi-directional converters. Phase currents in interleaved bi-directional converter are apt to be unbalanced due to circuit parameter error and switch operation difference. This problem causes the switch element failure and the reduced efficiency of the converter. Therefore, it is necessary that a certain balance control algorithm is provided in interleaved bi-directional converter system. In this paper, a balance control algorithm based on the circular chain control method is proposed. Further, in order to reduce the number of phase current sensors, this paper shows a simple method in which phase currents can be extracted indirectly through a DC-link current sensor in both charging and discharging modes. The validity and the effectiveness of the proposed phase currents balance control algorithm are illustrated through the simulation results.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.3
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• pp.352-359
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• 1999

This paper is a research for removing the alternators hunting which came about during the par-allel running. The four-pole six-phase alternator is equipped with the converter made out of twelve diodes to rectify all the waves. The hunting came about during the battery charging due to the hunting inducing point existed in r. p. m band 1575[rpm-1690[rpm] To remove the hunting inducing point We modified the four-pole six-phase alternator into the four-pole twevel-phase and increased the short-circuit ratio by decreasing the field coil pitch and increasing the field coil turns. But this method has two defects the first the alternator structure becomes complicating and the second the second the alternator equipped with the converter used in general purpose lately such as the car alternator can not be run in parallel wlthout modifying. To remove the defects the equalizing line was connected between the same phase of the alterna-tor to flow the synchronizing current which syncronize the phases of generator electromotive forces by which the alternator can be run in parallel without reference to the hunting inducing point and without modifying.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.84-90
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• 2013

This paper explains control methods of single-phase grid connected battery charger. Charging mode is control by Constant Current - Constant Voltage method and discharging mode is controlled by active-reactive power control method. Current control method is based on the synchronous reference frame(SRF) PI controller, and the second harmonic of battery current is compensated by an added L-C resonant circuit. Feasibility of the proposed control methods is verified through experiment with a prototype of 5kW single-phase grid connected battery charger.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.249-255
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• 2011

This paper is about the study of a stand-alone photovoltaic power conditioning system with an energy storage system with battery. The paper proposes the appropriate circuit model of stand-alone PV PCS considering the maintenance of the battery system. It also proposes the buck converter modeling by a state-space averaging method considering characteristics of solar cell. Lastly, it shows the way to choose the suitable battery and to design the model of bi-directional converter for charging and discharging battery. PSIM simulation is used to validate the proposed algothim of the system.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.72-80
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• 2001

In this paper, we present a systematic method of extracting the input parameters of poly-Si TFT(Thin-Film Transistor) for Spice simulations. This method has been applied to two different types of poly-Si TFTs such as ELA (Excimer Laser Annealing) and SMC (Silicide Mediated Crystallization) with good fitting results to experimental data. Among the Spice circuit simulators, the PSpice has the GUI(graphic user interface) feature making the composition of complicated circuits easier. We added successfully the poly-Si TFT model of AIM-Spice to the PSpice simulator, and analyzed easily to compare the electrical characteristics of pixels without or with the line RC delay. In the comparative results, the ELA poly-Si TFT is superior to the SMC poly-Si TFT in the charging time and the kickback voltage for the TFT-LCD (Thin Film Transistor-Liquid Crystal Display).