• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.304-309
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• 2005

This paper presents an electronic ballast using a step down converter, a low frequency inverter for high intensity short-arc discharge lamp. The proposed ballast is composed of a full-wave rectifier, a step down converter operated as a current source with power regulation and a low frequency inverter with external ignition circuit. The ignition circuit generates high voltage pulse of $3{\sim}5[kV]$ peak, 130[Hz] periodically. Moreover, it is able to reignite at regular intervals by protective circuit. As experimental results on the test, acoustic resonance phenomenon is eliminated by operating the low frequency square wave voltage and current. Lamp voltage, current and consumption power are measured 123.8[V], 8.1[A] and 1,002[W], respectively. It was confirmed that the designed ballast operate the lamp with a constant power.

• 전기학회논문지
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• 제65권6호
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• pp.1007-1012
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• 2016

Induction motors are used widely in driving load of a fluid, such as a pump or a fan in the industry. Induction motor has been generated the voltage drop by the occurrence of a high current during startup. In addition, high start-up current can act as a mechanical stress on the shaft of the motor. So there is need a way to reduce the starting current. Soft start method is one of the many ways to reduce the starting current. This method uses silicon-controlled rectifiers(SCRs) for varying value of the voltage applied to the motor. There is a case for fixing or changing the thyristor firing angle to adjust the magnitude of the voltage. Starting power factor of induction motor is very low compared to the normal operation. Soft starting with the firing angle fixed needs to be considered a low power factor at startup. In this study, we compared the direct start characteristics and soft start characteristics considering the low power factor at the time of start-up. It was possible to confirm that the starting current and the voltage drop is present differently according to the firing angle.

• Journal of Power Electronics
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• 제17권3호
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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.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.210-212
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• 2018

A new switching mode has been proposed to obtain high power factor and low THD in single stage AC-DC converter. The conventional voltage mode control in critical conduction mode distorts input current shape with poor THD in flyback topology. Once TRIAC dimmer is connected, visible flicker in the LED lamp is easily detected due to a lack of TRAIC holding current near the input voltage zero cross. The newly proposed method can shape the input current by providing a desired reference voltage so that low THD is obtained by ideal sinusoidal input current in case of no dimmer connection and flat input current performs good TRIAC dimmer compatibility in phase-cut dimming condition. To confirm the validity of the proposed method, theoretical analysis and experimental result from 8W dimmable LED lighting system are presented.

• Journal of Power Electronics
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• 제6권4호
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• pp.330-339
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• 2006

This paper deals with novel electronic ballast based on single-stage power processing topology using a symmetrical half-bridge inverter and current injection circuit. The half-bridge inverter drives the output parallel resonant circuit and injects current through the power factor correction (PFC) circuit. Because of high frequency current injection and high frequency modulated voltage, the proposed circuit maintains the unity power factor (UPF) with low THD even under wide variation in ac input voltage. This circuit needs minimum and lower sized components to achieve the UPF and high efficiency. This leads to an increase in reliability of ballast at low cost. Furthermore, to reduce cost, the electronic ballast is designed for two series-connected fluorescent lamps (FL). The analysis and experimental results are presented for ($2{\times}36$ Watt) fluorescent lamps operating at 50 kHz switching frequency and input line voltage (230 V, 50 Hz).

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.341-345
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• 2004

A high efficiency and low device stress voltage and current clamping BVS PWM asymmetrical half bridge converter is proposed in this paper. To achieve the ZVS of power switches along the wide load range, the transformer leakage inductor $L_{Ikg}$ is increased. Then, to solve the problem related to ringing in the secondary rectifier caused by the resonance between $L_{Ikg}$ and rectifier junction capacitors, the proposed converter employs a voltage and current clamping cell, which helps voltages and currents of rectifier diodes to be clamped at the output voltage and output current, respectively. Therefore, no RC-snubber for rectifier diodes is needed and a high efficiency as well as low noise output voltage can be realized. In addition, since all energy stored in $L_{Ikg}$ is transferred to the output side, the circulating energy problem can be effectively solved and duty loss does net exist. The operational principle, theoretical analysis, and design considerations are presented. To confirm the operation, validity, and features of the proposed circuit, experimental results from a 425W, 385-170Vdc prototype are presented.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.723-727
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• 2004

A new high-performance and low cost single switch energy recovery display driver for an AC plasma display panel (PDP) is proposed. Since it is composed of only one auxiliary power switch, two small inductors, and eight diodes compared with the conventional circuit consisting of four auxiliary power switches, two small inductors, eight power diodes, and two external capacitors, it features a much simpler structure and lower cost. Nevertheless, since the rootmean-square (RMS) value of the inductor current is very small, it also has very desirable advantages such as n low conduction loss and high efficiency. Furthermore, there are no serious voltage-drops caused by the large gas-discharge current with the aid of the discharge current compensation, which can also greatly reduce the current flowing through power switches and maintain the panel to light at n lower sustaining voltage. In addition, all main power switches are turned on under the zero-voltage switching (ZVS) and thus, the proposed circuit has a improved EMI, increased reliability, and high efficiency. Therefore, the proposed circuit will be well suited to the wall hanging PDP TV. To confirm the validity of the proposed circuit, circuit operations, features,and design considerations are presented and verified experimentally on a 6-inch PDP, 50kHz-switching frequency, and sustaining voltage 141V based prototype.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.195-198
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• 2000

In this paper the insulation characteristics test results of 25 low-voltage induction motors($3\phi$, 5HP, 380V) are presented. Five different types of insulation techniques are applied to 25 motors. The maximum partial discharge (PD) magnitude ($\textrm{Q}_{m}$) discharge inception voltage (DIV) dissipation factor tip-up ($\Delta$tan$\delta$) and rate of change in AC current($\Delta$I) are measured by PD and AC current tests. Also the insulation breakdown tests by high voltage pulse are performed and the corresponding breakdown voltage are obtained.

• ETRI Journal
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• 제43권5호
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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.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권1호
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• pp.18-22
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• 2005

We have proposed and fabricated a dual gate AlGaN/GaN high electron mobility transistor (HEMT), which exhibits the low leakage current and the high breakdown voltage for the high voltage switching applications. The additional gate between the main gate and the drain is specially designed in order to decrease the electric field concentration at the drain-side of the main gate. The leakage current of the proposed HEMT is decreased considerably and the breakdown voltage increases without sacrificing any other electric characteristics such as the transconductance and the drain current. The experimental results show that the breakdown voltage and the leakage current of proposed HEMT are 362 V and 75 nA while those of the conventional HEMT are 196 V and 428 nA, respectively.