• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.2
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• pp.88-94
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• 1999

This paper describes the high efficiency inverter ballast circuit using very cheap microprocessor, which has been developed by the author. A variety of soft-switching techniques have been proposed to reduce the switching losses and EMI publems that accur with higher switching frequencies in switched inverter ballast 1be inverter ballast circuit, which employs a temperature sensing circuits has been also proposed to improve starting performance of the fluorescent lamps. That is, the inverter ballast circuit, which employs a soft-starting circuits and soft-switching techniques to implement the power factoc correcticn and to mitigate of power-loss and iocrease a life time of the fluorescent lamps, has become an attractive performance forballasting the fluorescent lamps. In this paper, the operation and the control of the inverter ballast are described in detail and experimental results are presented. As the experimental results, when enviroment temperatture is at TEX>$-40^{\circ}C$, the inverter ballast circuit has low THD(4.8%) of the input current and large power factor(98%) of the lamp current. The proposed improved ballast circuit awears to be a good performance for ballasting fluorescent lamps. lamps.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.278-280
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• 1999

This paper proposes controlling of temperature in an oven by using 4 bits Integral - Cycle Binary Rate Modulation (IBRM) method and ac line with frequency 50 Hz. Microcontroller MCS-51 controls IBRM according to Proportional Integral controller (PI) function. Discrete signals are used in the system modeled by using Ziegler Nichols principle for analyzing the stability before designing the system. This procedure makes it easy to investigate system response. The system is implemented by 4 bits digital circuit which gives 320 patterns of ac signal fur controlling the generation of energy for 3,000 watts thermal coil every 20 ms of each cycle. We divide scan time (Ts$\sub$n/) in to 20 intervals, 1 ms interval is selected to generate 16 patterns IBRM. Because of this method gives the ripple lower than 2% it generates less noise fur system. Moreover, we can consider whole system from the time model of control procedure and IBRM algorithm at 40-200$^{\circ}C$ with ${\pm}$ 1$^{\circ}C$ error in the 1 cubic meter oven.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.10
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• pp.381-386
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• 2016

An optimization algorithm is developed based on a simulation case of a single family house model equipped with PV arrays. To increase the nationwide use of PV power generation facilities, a market-competitive electricity price needs to be introduced, which is determined based on the time of use. In this study, quadratic programming optimization was applied to minimize the electricity bill while maintaining the indoor temperature within allowable error bounds. For optimization, it is assumed that the weather and electricity demand are predicted. An EnergyPlus-based house model was approximated by using an equivalent RC circuit model for application as a linear constraint to the optimization. Based on the RC model, model predictive control was applied to the management of the cooling load and electricity for the first week of August. The result shows that more than 25% of electricity consumed for cooling can be saved by allowing excursions of temperature error within an affordable range. In addition, profit can be made by reselling electricity to the main grid energy supplier during peak hours.

• Journal of information and communication convergence engineering
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• v.13 no.2
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• pp.139-143
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• 2015

A push-push voltage controlled dielectric resonator oscillator (VCDRO) with a modified frequency tuning structure using broadside couplers is investigated. The push-push VCDRO designed at 16 GHz is manufactured using a low temperature co-fired ceramic (LTCC) technology to reduce the circuit size. The frequency tuning structure using a broadside coupler is embedded in a layer of the A6 substrate by using the LTCC process. Experimental results show that the fundamental and third harmonics are suppressed above 15 dBc and 30 dBc, respectively, and the phase noise of push-push VCDRO is -97.5 dBc/Hz at an offset frequency of 100 kHz from the carrier. The proposed frequency tuning structure has a tuning range of 4.46 MHz over a control voltage of 1-11 V. This push-push VCDRO has a miniature size of 15 mm×15 mm. The proposed design and fabrication techniques for a push-push oscillator seem to be applicable in many space and commercial VCDRO products.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.61-65
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• 2017

In this paper a prototype of high frequency heating power supply system based on the high frequency heating principle is designed to take the place of acupuncture, moxibustion, warm dressing treatment and some other traditional physical therapy methods. Which possess the advantages of low cost, convenient, easy operation and good effect. The high frequency heating power supply can generate a pulse voltage of more than 1KV with 300KHz switching frequency to heat the patient's skin. The skin temperature can reach to $41{\sim}42^{\circ}C$. The peak current control method is used to maintain the skin temperature in the designed range. The design of the main circuit is based on the flyback converter topology. An easier and practical design method is proposed in this paper. The power supply system prototype is verified to be stable and reliable by both the simulation and experimental results.

• Journal of IKEEE
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• v.23 no.1
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• pp.261-265
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• 2019

We analyze the failure rate change of a conventional bidirectional converter and a modified one which moves an output capacitor towards propulsion battery. We analysis of the circuit structural homogeneity and the difference between both converters, and confirm that the capacitor working voltage is reduced by changing the capacitor position. After obtaining the capacitor failure rate according to voltage stress factor and operating temperature, it is applied to the fault-tree of the bidirectional converter to obtain the overall failure rate of the converter. We analyzes the advantages and disadvantages of design changes by comparing and analyzing the failure rate and mean time between failures (MTBF) according to operating temperature and capacitance value.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.238-242
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• 2004

The paper describes an automatic frequency control current-fed inverter for forging applications. The IGBT in series with diodes as its switching devices in the inverter circuit which is of full-bridge type. The operating frequency is automatically tracked to maintain a small constant leading phase angle when load parameters change. The load voltage is controlled to protect the switches. The output power can be adjusted by varying the input current from phase controlled rectifiers which is a part of current source. The system has been operated at 15-17 kHz. The output power transferred to the load is 1,595 watts. It can heat the steel work pieces with 15 mm diameter and 120 mm long from room temperature to approximately 1100 $^{\circ}C$ within 20 seconds with 0.97 leading power factor on the input side.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.5 s.311
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• pp.28-35
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• 2006

This paper presents a new 3.3-1 V synchronous buck DC/DC converter that employs CMOS operational transconductance amplifiers (OTAs) as circuit-building blocks. An error amplifier OTA in a PWM circuit is compensated for to improve temperature stability. The temperature coefficient of the transconductance gain of the compensated OTA is less than $150\;ppm/^{\circ}C\;over\;0-100^{\circ}C$. The HSPICE simulation results of the $0.3{\mu}m$ standard CMOS technology show that the efficiency of the proposed converter is as high as 80% in the load current range of 40-125 mA. These results show that the proposed converter is adequate for use in battery-operated systems.

• Journal of Power Electronics
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• v.3 no.2
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• pp.99-114
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• 2003

This paper presents a feasible development on a highly accurate quick response adjustable speed drive implementation fur general purpose induction motor which operates on the basis of sensorless slip frequency type vector controlled sine-wave PWM inverter with an automatic tuning machine parameter estimation schemes. In the first place, the sensorless vector control theory on the three-phase voltage source-fed inverter induction motor drive system is developed in slip frequency based vector control principle. In particular, the essential procedure and considerations to measure and estimate the exact stator and rotor circuit parameters of general purpose induction motor are discussed under its operating conditions. The speed regulation characteristics of induction motor operated by the three-phase voltage-fed type current controlled PWM inverter using IGBT's is illustrated and evaluated fur machine parameter variations under the actual conditions of low frequency and high frequency operations for the load torque. In the second place, the variable speed induction motor drive system, employing sensorless vector control scheme which is based on three -phase high frequency carrier PWM inverter with automatic toning estimation schemes of the temperature -dependent and -independent machine circuit parameters, is practically implemented using DSP-based controller. Finally, the dynamic speed response performances for largely changed load torque disturbances as well as steady state speed vs. torque characteristics of this induction motor control implementation are illustrated and discussed from an experimental point of view.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.7
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• pp.1-9
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• 2012

In this paper, resistance temperature detector (RTD) integrated into the LED package is proposed in order to solve the temperature dependence of LED's optical properties. To measure the package temperature in real time, the RTD type temperature sensor having excellent accuracy and linearity between temperature change and resistance change was adopted. A stable metallic film is required for long term reliability and stability of the RTD type temperature sensor. Therefore, deposition and annealing condition for the film were determined. Based on the determined condition, the RTD type temperature sensor with the sensitivity of about $1.560{\Omega}/^{\circ}C$ was fabricated inside the LED package. In order to configurate the LED package system keeping the constant brightness regardless of the temperature, additional conversion circuit and control circuit boards were fabricated and added to the fabricated LED package. The proposed system was designed to compensate the light intensity caused by temperature change using the variable duty rate of driving current. As a result, the duty rate of PWM signal which is the output signal of the configurated system was changed with the temperature change, and the duty rate was similarly varied with the target duty rate. Consequently, it was focused the fabricated RTD can be used for compensating the optical properties of LED and the LED package which exhibits constant brightness regardless of the temperature change.