• Journal of Advanced Marine Engineering and Technology
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• v.17 no.5
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• pp.71-85
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• 1993

The Cycloconverter that the author is going to treat in this paper, has strong advantages over the D.C. Link Inverter in points of chattering torque problem and natural commutation. Thus, the Cycloconverter is expected to be well applied to large and low-speed machines which require better speed control at low frequency. But the control circuit of Cycloconverter has two weak points described as follows. 1) Because of its rather complicated control circuit, it is likely to be illoperating due to unexpected noise signals, thus the higher the accuracy and reliability of the circuit is required to be, the more the circuit may cost. 2) Because the load current is not purely sinusoidal, the Cycloconverter may possibly be destroyed in case of inaccurate convert switching resulted from the difficulties in detecting the load current-zero and the current direction at the moment. In this paper, the author first of all intends to design and build a modified VVVF-type Noncirculating Current Cycloconverter to which recently proposed control methods are applied for improving the circuit simplicity, the control performance, and the system reliability. And then, experiments for observing the output waveforms of the Cycloconverter which is controlled by Singled-Board Computer using 8086 16-bit microprocesser are carried out. Finally the author concludes the result of this study as follows. 1) By replacing the conventional analog control circuits such as Reference Wave Generator, Cosine Timing Wave Generator, and Comparator with softwares, a great circuit simplicity is achieved. 2) The output of the designed Cycloconverter changes its frequency very fast without showing discontinuity of its waveform, and this waveform characteristics enables the smooth speed control of Induction Motor. 3) The design control circuit of Cycloconverter can be applied to the systems of 12 or 24 pulses because of its short processing period.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.4
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• pp.617-624
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• 2023

Recently, miniaturization and low power consumption of electronic products and improved efficiency and power factor improvement have become a matter of great interest. In this paper, an AC-DC converter based on PWM control was designed and made. The AC-DC converter is designed with a structure in which one rectifier circuit and one output voltage control circuit are connected in series. The rectifier circuit is a diode-based single phase full-wave current circuit and the output voltage control circuit is a DC-DC conversion circuit based on PWM control. Arduino was used as the main control device for PWM control, and LCD was configured at the output stage so that the control result could be checked. The error between the output voltage displayed on the oscilloscope and LCD and the target output voltage was confirmed through repeated experiments with the test circuit, and the validity of the proposed design methodology was confirmed by showing an error rate of about 5% based on the oscilloscope measurement value.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.255-258
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• 1996

This paper describes a DC voltage controller for the DC power supply which is constructed using the full-bridged MOS-FET DC-to-RF power inverter and rectifier. The full-bridged MOS-FET DC-to-RF inverter consisting of four MOSFET arrays and an output power transformer has a control function which is able to control the RF output power when the widths of the pulse voltages which are fed to four MOS-FET arrays of the fall-bridged inverter are changed using the pulse width control circuit. The power conversion efficiency of the full-bridged MOS-FET DC-to-RF power inverter was approximately 85 % when the duty cycles of the pulse voltages were changed from 30 % to 50 %. The RF output voltage from the full-bridged MOS-FET DC-to-RF inverter is fed to the rectifier circuit through the output transformer. The rectifier circuit consists of GaAs schottky diodes and filters, each of which is made of a coil and capacitors. The power conversion efficiency of the rectifier circuit was over 80 % when the duty cycles of the pulse voltages were changed from 30 % to 50 %. The output voltage of the rectifier circuit was changed from 34.7V to 37.6 V when the duty cycles of the pulse voltages were changed from 30 % to 50 %.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.314-315
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• 2011

This paper introduces the design and control method of braking chopper circuit which can supply input power to ventilation inverter of traction control system. The DC input voltage from auxiliary block (static inverter) is normally used as an input of ventilation inverter. It converts DC input to AC output voltage to drive cooling fans for traction control system and traction motors. The electrical braking force is very important for high speed train to guarantee safety even though the train is running in the dead section where the pantograph voltage is not supplied. When the high speed train decelerate speed in dead section, the regenerative energy is dissipated by braking resistor. This paper proposed the braking chopper control method to implement rheostatic braking function and the appropriate chopper circuit for supplying voltage source to ventilation inverter during rheostatic braking mode. The proposed chopper circuit makes it possible for traction control system to regenerate power continuously regardless of the existence of pantograph voltage. The feasibility of proposed braking chopper control and circuit were proven by inertia load test and actual train field test.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.09a
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• pp.82-88
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• 2001

Manufactured easy elevator can drives from the first floor to fifth floor as sequence control circuit in cause opening than existing equipment of experiment and practice, the structure of in the first implementation process are hand-worked control component with push-button, L/S and relay, it is structured a lamp to express that the door open and moving of cage by mechanical action of For/Rev motor-braker of which load. The second structure of implement process to control from the first floor to the fifth floor with the PLC elevator program can control by the sensor of hand-operated function of L/Sl~L/S5 in time that the S/Wl~S/W5 of PLC control panel operates to the For/Rev. The function of two kind process that an elevator is driven by PLC program and the sequence control relay circuit is a mechanical relay sequence control field and it is equipment apparatus of it to get appropriately the technology of For/Rev in that mechanical operating cause of a load using the PLC program. Also the wring circuit using a plug, dissembly. the circuit and the principle of component, and PLC program with the function test can be used the implementation field to the total technology theory about FA.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.124-130
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• 1997

The main switch of high-frequency boost converter may be failed because the high switching current or voltage can damage this switch. The high switching stress can be reduced by snubber circuit. In this paper, a new passive snubber circuit which can recover trapped snubber energy without added control is proposed for boost converter. The control of boost converter with proposed snubber is the same as the conventional one. In addition, the energy recovery circuit can be implemented with a few passive components. The analysis for proposed circuit is presented, and the validity of the circuit is verified through simulation and experiment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2487-2494
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• 2012

In this paper, a thermal energy harvesting circuit with MPPT control is designed. MPPT(Maximum Power Point Tracking) control function is implemented using the linear relationship between the open-circuit voltage of a thermoelectric generator(TEG) and its MPP voltage. The designed MPPT control circuit traces the maximum power point by periodically sampling the open circuit voltage of a TEG, makes the reference voltages using sampled voltage and delivers the maximum available power to load. Simulation results show that the maximum power efficiency of the designed circuit is 94%. The proposed thermal energy harvesting circuit is designed with $0.35{\mu}m$ CMOS process, and the chip area except PAD is $1168.7{\mu}m{\times}541.3{\mu}m$.

• Journal of Welding and Joining
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• v.13 no.4
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• pp.75-84
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• 1995

In GMA welding of sheet metal, the short circuit metal transfer mdoe is preferred because of its low heat input and capability of bridging the root gap. The molten electrode is transferred to the workpiece during repectitive short circuit in the model. The waveform of welding current or voltage and the frequency of short circuiting are affected by a number of factors including: magnitude of welding current and voltage, root gap, electrode extension, power supply characteristics, and so on. In this study experimental models were proposed, which are able to determine the relationship between the root gap and short circuit frequency and the relationship between the root gap and appropriate welding speed that produces the good quality of back bead without burn through. Using the experimental models, the root gap can be obtained from measuring the short circuit frequency, and then the appropriate weldig speed to the root gap can be determined. Thus a back bead control system was constructed by controlling the welding speed for maintaining the quality of back bead. The developed system has shown the successful capability of back bead control.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.43-46
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• 2012

In this paper, high efficiency power amplifier is implemented with high gain amplifier. Two-stage amplifier using adaptive bias control circuit improve efficiency at low input power. Fixed bias circuit and adaptive bias circuit both have about 76 % efficiency at maximum power level. However amplifier using an adaptive bias control circuit has 70 % at 6 dBm input power level when the amplifier using fixed bias circuit has 50%. The proposed power amplifier using the adaptive bias control circuit can have high efficiency at lower power level.

• Journal of Practical Engineering Education
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• v.9 no.2
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• pp.99-106
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• 2017

The most important thing in STEAM education is to enhance students' interest and understanding of science and technology. In this paper, we propose basic circuit system design and control method applicable to STEAM fusion education. The circuit system design practice using the breadboard is designated as an essential curriculum in the corresponding department at the high school and college level in the domestic curriculum. However, there is a lack of STEAM convergence implementation examples that can easily understand circuit system design and control methods. Therefore, we proposed and tested a method to implement and control a media art type circuit system.