• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.1
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• pp.45-49
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• 2020

In this paper, we prepared miniature fuse fabricated with carbon nanotube (CNT) fiber for the use of low rated current under 1 A and high speed operation under 4ms. CNT fuses were fabricated in the form of universal modular fuse (UMF) with different diameter of CNT fibers defined by multiplying the CNT threads. Electrical properties of the CNT fuses were measured such as resistance, rated current, and operation time with current. Resistance of the CNT fuse decreased and rated current increased with the diameter of the CNT fuses, respectively. Consequently, the operation time with current increased with the diameter of the CNT fuses. The CNT fuses fabricated in this work had broad range of low rated current from 0.05 to 1.25 A by multiplying the CNT threads. Operation time was measured about 3.6ms which was applicable to the UMF.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.24-31
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• 2018

An induction heating (IH) resonant converter, as well as its coil design method, is proposed in this study to improve the heat capability of low- and high-resistance IH vessels. Conventional IH resonant converters have been designed only for heating high-resistance containers designed for IH application. Thus, the primary current in the resonant tank becomes extremely high to transfer the rated power when the converter heats the low-resistance vessel. As a result, the rated power cannot be transferred due to overcurrent flows against the rated switch current. Hence, the optimal number of coil turns and proper operating frequency to heat high- and low-resistance vessels are proposed in this study by analyzing an IH load model. Simulation and experimental results using a 2.4 kW prototype resonant converter and its IH coil validate the proposed design.

• ETRI Journal
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• v.43 no.5
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• pp.891-899
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• 2021

We propose a stray inductance extraction method on power modules of the few-kilovolts/several-hundred-amperes class using only low voltages and low currents. The method incorporates a double-pulse generator, a level shifter, a switching device, and a load inductor. The conventional approach generally requires a high voltage of more than half the power module's rated voltage and a high current of around half the rated current. In contrast, the proposed method requires a low voltage and low current environment regardless of the power module's rated voltage because the module is measured in a turn-off state. Both theoretical and experimental results are provided. A physical circuit board was fabricated, and the method was applied to three commercial power modules with EconoDUAL3 cases. The obtained stray inductance values differed from the manufacturer-provided values by less than 1.65 nH, thus demonstrating the method's accuracy. The greatest advantage of the proposed approach is that high voltages or high currents are not required.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.343-346
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• 2002

In recent, complex SVPWM (Space Vector PWM) algorithm can be easily implemented by high performance microprocessor and DSP. Various SVPWM techniques are widely studied due to the advantages of low harmonic distortion and high use ratio of D.C. link voltage. Most of various studies for improving of VS-PWM inverter performance are concentrated about switching pattern and zero pulse pattern split algorithms. However, dc link voltage that is determined at rated load and speed conditions is not proper in the low speed and under rated load. In this paper, analysis of current ripple with digitally implemented SVPWM inverter is introduced according to link voltage. The optimal link voltage in the designed inverter system and load condition is provided in order to suppress output voltage error and current ripple. As remaining the effective voltage vector interval per sampling period sufficiently, additional voltage error and current ripple are suppressed. The proposed algorithm is verified through digital simulation and experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.12
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• pp.1-8
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• 2012

The performance and lighting characteristics of the LED depend on cooling condition because the power LED generates lots of heat. In this paper, the effect of the generated heat from power LED module on lighting characteristics and performance is measured and evaluated. For experiments, the transient temperature of a power LED module with cooling condition is measured. In addition, the temperature and lighting characteristics of the LED module are measured during the steady state. As a result, the cooling condition is less effective on the lighting characteristics of the LED module at rated current but the cooling condition extremely affects those of the LED module over the rated current. Because high temperature of the power LED module causes the low phosphor conversion, luminance efficiency becomes low and color temperature becomes high. When power LED module are driven over the rated condition, higher temperature is directly related to lighting characteristics and performance of the LED module rather than higher current.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.91-98
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• 1999

An integrated ZCS quasi-resonant converter(QRC) for the power factor correction with a single switch is presented in this paper. The power factor correction can be achieved by the discontinuous conduction mode(DCM) operation of the input current. The proposed converter gives the good power factor, low line current harmonics, and tight output regulation. The input current waveform of the prototype designed using design equations shows about 15% of total harmonic distortion at rated condition. Also, the efficiency and power factor can be obtained about 86% and 0.985, respectively, at rated condition. The proposed converter is suitable for a low power level converter with a tightly regulated low output voltage and switching frequency of more than several hundreds kHz.

• Journal of Power Electronics
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• v.17 no.3
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• pp.590-600
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• 2017

This paper presents a ripple-free input current modified interleaved boost converter for high step-up applications. By integrating dual coupled inductors and voltage multiplier techniques, the proposed converter can reach a high step-up gain without an extremely high turn-ON period. In addition, a very small auxiliary inductor employed in series to the input dc source makes the input current ripple theoretically decreased to zero, which simplifies the design of the electromagnetic interference (EMI) filter. In addition, the voltage stresses on the semiconductor devices of the proposed converter are efficiently reduced, which makes high performance MOSFETs with low voltage rated and low resistance $r_{DS}$(ON) available to reduce the cost and conduction loss. The operating principles and steady-state analyses of the proposed converter are introduced in detail. Finally, a prototype circuit rated at 400W with a 42-50V input voltage and a 400V output voltage is built and tested to verify the effectiveness of theoretical analysis. Experimental results show that an efficiency of 95.3% can be achieved.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.155-157
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• 2005

This paper analyzed the adoption possibility of a low cost single phase active power filter as the neutral current reduction device in three-phase four-wire power system with the balanced or/and unbalnaced nonlinear load conditions. Proposed system can make neutral line current to within rated vale without the phase current THD change of the installed phase line.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.477-478
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• 2016

This paper introduces a repetitive controller in low switching frequency applications. Generally, A high power UPS system has a high rated current. And the system usually consist of high power IGBT has a tail current. So the high power UPS system operates in low switching frequency because of this tail current. The repetitive controller improve THD of output voltage or current by reducing the steady state error. The effect of the repetitive controller is proved by simulations.

• Journal of the Korean Society of Safety
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• v.30 no.5
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• pp.8-13
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• 2015

Molded Case Circuit Breakers (MCCBs) are typically used to provide over current protection for electrical safety caused by short circuit faults and overloads in indoor low voltage power systems. The MCCB automatically connects and disconnects loads from the electrical source when the current reaches a value and duration that will cause an excessive. However, the MCCB sometimes is not interrupted due to a malfunction, nuisance tripping, or in a fire. Ensuring electrical safety is very important in a indoor low voltage power system. This paper presents the operating characteristics of MCCBs according to a temperature rise from room temperature to 160 degrees Celsius delivered by a radiant panel heater. The ABS 54c(rated current: 30A) of the hydraulic magnetic trip type was used in the experiments. The signals of temperature, voltage, and current were measured using the high accuracy Signal Conditioning Extensions for Instrumentation (SCXI) measurement system with the LabVIEW program manufactured by National Instruments. The operating characteristics were measured as functions of current amplitude and ramp-up rate. The MCCB tripping time decreased as a result of increasing current amplitude and ramp-up rate under a temperature rise condition, because the temperature and level of the current are directly proportional to the tripping time. Additionally, an instantaneous operation was observed after 8 times of the rated current, and the MCCB began to melt a surface temperature of around 300 degrees Celsius of. The experimental results coincided well with the operating curve.