• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.6
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• pp.29-37
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• 2012

As the demand for the fresh non-thermal food is increased, it is required to develop the fast and perfect sterilization method. The conventional sterilization method using ultraviolet lamp has some disadvantages such as imperfect sterilization and longer process time. In this research, IPL(Intense Pulsed Light) sterilization system is introduced to overcome the drawbacks of the conventional system, and suitable power supply architecture for the system is discussed. Since the IPL sterilization system uses Zenon lamps which requires the 600~2,100[V] for the lightning and 16~30[kV] for the trigger, the converter for the system should be able to generate the high voltage and to discharge the large amount of energy instantaneously. In this research a new power system architecture which has a modified forward converter topology with two switches for generating high voltage and a capacitor bank to control the energy for the lightning by switching is introduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.569-575
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• 2020

Recently, research on renewable energy technologies has come into the spotlight due to rising concerns over the depletion of fossil fuels and greenhouse gas emissions. Demand for portable electronic and wearable devices is increasing, and electronic devices are becoming smaller. Energy harvesting is a technology for overcoming limitations such as battery size and usage time. In this paper, the V-I characteristic curve and internal resistance of thermal electric devices were analyzed, and MPPT control methods were compared. The Perturbation and Observation (P&O) control method is economically inefficient because two sensors are required to measure the voltage and current of a Thermoelectric Generator(TEG). Therefore, this paper proposes a new MPPT control method that tracks MPP using only one sensor for the regulation of the output voltage. The proposed MPPT control method uses the relationship between the output voltage of the load and the duty ratio. Control is done by periodically sampling the output voltage of the DC-DC converter to increase or decrease the duty ratio to find the optimal duty ratio and maintain the MPP. A DC-DC converter was designed using a cascaded boost-buck converter, which has a two-switch topology. The proposed MPPT control method was verified by simulations using PSIM, and the results show that a voltage, current, and power of V=4.2 V, I=2.5 A, and P=10.5 W were obtained at the MPP from the V-I characteristic curve of the TEG.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.669-672
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• 2001

Generally, previous converter is divided into two categories to get high power factor and good output regulation. These two categories can be combined a category with a main switch. These converter is called Single Stage PFC Converter. This approach has good electrical characteristics of high power factor and fast output voltage regulation. The cost and size are important factor to design the converter in low power system. Even single stage can reduce the size and cost, but this approach needs to have additional circuit like control, PWM circuit. To improve these demerits, Top switch is one of good choice In reduce and size in low power single stage converter. Because it has the ability of current limit, thermal protection, oscillator, control circuit as well as a main switch ability.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.3
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• pp.242-249
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• 2011

The proposed converter has easy device selection for high step-up and high power applications since boost half bridge and voltage doubler cells are connected, respectively, in parallel and series in order to increase output power and voltage. Especially, optimized design of high frequency transformers is possible owing to reduced turn ratio and eliminated dc offset, and distributed power through three cores is beneficial to low profile and thermal distribution. The proposed converter does not necessitate start-up circuit and additional clamp circuit due to the use of whole duty range between 0 and 1 and is suitable for applications with wide input voltage range. Also, high efficiency can be achieved since ZVS turn on of switches are achieved in wide duty cycle range and ZCS turn on and off of diodes are achieved. The proposed converter was validated through 5 kW prototype.

• Journal of Sensor Science and Technology
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• v.9 no.4
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• pp.288-296
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• 2000

Thin-film chromel-alumel multijunction thermal converters with a low output resistance of $64{\sim}85\;{\Omega}$ showed approximately the square law-dependent input-output relation. The voltage responsivities were very low with $0.34{\sim}0.67\;V/W$ in air and $1.15{\sim}1.48\;V/W$ in vacuum, respectively, and the ac-dc voltage transfer error was very large with about +340 ppm in the frequency range of $40\;Hz{\sim}10\;kHz$ in the case of 1 V-input sinewave rms voltage. It can be concluded that the large transfer error of the thermal converter was mainly caused by the low voltage responsivity and the large heat loss due to low output resistance, which implies that the optimization for small ac-dc transfer error is required.

• Journal of Sensor Science and Technology
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• v.14 no.5
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• pp.350-356
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• 2005

We have developed a dual-channel type automatic measurement system to evaluate AC-DC current transfer difference of the thermal current converter(TCC) which is primary standard of AC current. The output drift effect of the TCC is minimized by measuring simultaneously the output voltages of two TCCs using voltmeter. Furthermore, the offset voltage of the voltmeter is cancelled nearly out by taking the average values of two outputs of TCCs measured with the forward-reverse directions using dual channel scanner. The uncertainties of the automatic system were 7 to $86{\mu}A/A$ for 3 mA to 10 A at 40 Hz to 20 kHz, which were evaluated by the comparisons between adjacent range of TCCs and inter-comparison with national measurement institute of Germany(PTB). The capability for ac-dc transfer difference measurement was improved by one order compared with that for the manual ac-dc measurement system.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.9
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• pp.37-45
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• 1999

For the purpose of reducing the output voltage fluctuation of thin film multijunction thermal converter, EVANOHM alloy-S and chromel-alumel thermocouple were used as a thin film heater material and as a thermoelement of thrmopile, respectively. The temperature coefficient of the resistance of thin film EVANOHM alloy-S heater was about $1.4 {\times} 10^4/^{\circ}C$, which is very small compared to other materials, and thin film chromel-alumel thermocouple showed relatively small difference of the Seebeck coefficients about $38 {\mu}V/K$. The output voltage fluctuation of the thermal converter was about 0.06% for the initial 120 seconds in air and decreased considerably after preheating for 5 minutes or more. The respective AC-DC voltage and current transfer error ranges of the thermal converter were about ${\pm}$1.6 ppm and ${\pm}$0.7 ppm in the frequency range from 10Hz to 10 kHz and increased remarkably below 10 Hz or above 10 kHz.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.6
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• pp.494-502
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• 2014

This paper presents a control method of the modular multilevel converter - high-voltage direct current (MMC-HVDC) system to regulate grid voltage on the basis of the Jeju Island power system. In this case, the MMC-HVDC system is controlled as a static synchronous compensator (Statcom) to exchange the reactive power with the power grid. The operation of the MMC-HVDC system is verified by using the PSCAD/EMTDC simulation program. The Jeju Island power system is first established on the basis of the parameters and measured data from the real Jeju Island power system. This power system consists of two line-commutated converter - high-voltage direct current (LCC-HVDC) systems, two Statcom systems, wind farms, thermal power plants, transformers, and transmission and distribution lines. The proposed control method is then applied by replacing one LCC-HVDC system with a MMC-HVDC system. Simulation results with and without using the MMC-HVDC system are compared to evaluate the effectiveness of the control method.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.74-76
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• 1996

This measurement method described in this paper can be applied for the accurate determination for voltage and current of inverter with harmonics. The method, based on a thermal principle, relies on adaptation of the measurement thermal e.m.f to signal of inverter and comparison of AC to DC signals. The performance of the measurement system is compared with calculated results and reference power system. With this method, an accuracy of 0.1% can be achieved.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.761-768
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• 2017

This paper deals with the performance analysis of three phase induction motor considering its stator side faults and operating thermal limits. The speed control of induction motor using three phase boost converter operated by a MOSFET switch and a PI controller is demonstrated and presented in this article. IGBTs switches are used for inverter drive mechanism. The experimental result of speed control of induction motor using voltage control technique clearly shows better accuracy than conventional methods of speed control. A three phase 1HP 415V 0.78 kW 4 Pole induction motor is designed using motor solver software. Based on the parameters used in the software thermal analysis of induction motor is done and torque variation with conductor area, efficiency, output curve, losses in different parts of motor has been obtained. Also different types of faults namely under voltage, over voltage, stator imbalanced voltage, turn to turn, locked rotor bar, wrong alignment of rotor bar with respect to stator are studied and fault analysis is performed. Hence comparison is made based upon the results obtained before and after faults.