• Transactions of the Korean Society of Automotive Engineers
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• 제14권6호
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• pp.24-33
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• 2006

This experiment explains about electrical braking equipment which will be used for 1.2kW PEMFC HEV. The equipment is made of BLDC motor and super capacitor(EDLC). The circuit is designed for regeneration braking that can save the energy from low voltage of generation with BLDC motor. Increasing a regeneration energy from braking system is effected with regeneration current and SoC of super capacitor(EDLC). Electrical braking in electrical vehicle is suitable for regeneration braking with dynamic braking together.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(2)
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• pp.333-336
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• 2000

Modem standard CMOS process technology suffer from so large amount of PVT i.e process, voltage and temperature variation over 30% of its desired value that accurate resistor value is hard to be achieved. A filter using switched-capacitor(SC) circuit has a time constant proportional to relative capacitor area ratio rather than its absolute value. If the PLL's loop filter were made out of SC circuit, there could be much less PVT variation problem. Furthermore, programmability on the loop filter can be achieved In this paper, we present the PLL with SC loop filter. The accuracy provided by SC filter would be helpful to enhance PLL's locking behaviour.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.675-678
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• 2000

Using the principle of the cross capacitor, a precise system for measuring the electric constants of liquids has been developed. The four electrodes of the cross capacitor were formed around fused-silica tube by plating a gold film. The effect of a non-uniform tube wall ok the measured permittivity was investigated As the individual characteristics of the tubes were determined to be constant, the pure dielectric constants extracted from any effect of the fused-silica material could be precisely derived with uncertainty of less than ${\pm}$ 0.02∼0.05 %.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제22권9호
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• pp.94-102
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• 2008

Capacitor switching is essential for the economic operation and proper voltage control of KOREA electric utility distribution system. Voltage transients produced by capacitor switching (around 2.0 per unit at substation and 2.5 or less per unit at customer site, and lasting less then 1[ms]) do not have the magnitude or duration to interfere with the operation of computers, but they do disrupt the operation of adjustable speed drivers. The result of our research, ASD manufacturers should learn from the computer industry and design products that will operate satisfactory In the electrical envelopment in which they will be placed. In this case history, the inductors on the input to ADSs in order to prevent nuisance tripping from capacitor switching(and other causes within the apartment) proved to be an effective, low-cost solution.

• Journal of the Korean Professional Engineers Association
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• 제33권1호
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• pp.94-105
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• 2000

The purpose of this paper is to obtain the improved reliability and optimal control of the half-bridge inverter for induction heating system. Parasitic inductance components within the inverter circuit for induction heating including the loss-less turn-off snubber capacitor considerably affect stable operation and noise level of the system. This paper analyzes the effect of the inductance in detail and presents a new snubber configuration suitable for the half-bridge inverter to effectively reduce it. In the half-bridge inverter for induction heating the capacity of the loss-less snubber capacitor determines the switching losses because the zero voltage turn-on switching is used. However, the increase of the capacitor is limited by the system specifications, so that it is not easy work to reduce the switching loss. To effectively overcome the limitation, this paper introduces an active auxiliary resonant circuit suitable for the half-bridge inverter circuit, which operates actively according to the variation of load condition. It is also one of the most important study issues for the half-bridge inverter driven induction heater that the development of optimal control scheme considering varied load condition should be achieved. The control strategy ensures a very stable operation of overall inverter system and zero voltage turn-on switching irrespective of sensitive load parameter variations, in particular, even under the non-magnetic materials.

• The Transactions of the Korean Institute of Power Electronics
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• 제26권4호
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• pp.277-284
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• 2021

A single and three phase-compatible single-stage EV charger without electrolytic capacitor is proposed in this study. DC battery-charging current is inherently guaranteed in the three-phase grid due to three output currents with a phase shift of 120° between each other. The proposed EV charger can provide a DC battery charging current for the single-phase grid through the integrated active power decoupling circuit without using additional switches. The proposed EV charger ensures ZVS turn-on of all switches with wide grid and battery voltage ranges. The 11 kW prototype of the proposed EV charger demonstrates a peak efficiency of 97.01% and a power density of 5.58 kW/L.

• The Transactions of the Korean Institute of Electrical Engineers P
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• 제65권4호
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• pp.285-291
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• 2016

A light-emitting diode (LED) has been increasingly applied to various industrial fields and general lightings because of its high efficiency, low power consumption, environment-friendly characteristic and long lifetime. To drive the LED lighting, a power converter with the constant output current is needed. Among many power converters, the flyback converter is chosen by many converter designers due to high power density, structural simplicity, and miniaturization. In this converter, an electrolytic capacitor is generally chosen for the stabilization of the DC voltage because of having the large capacitance and the low price. However, the disadvantages are the short expected life time and 120Hz ripple currents on the converter output node. In this paper, a single-stage dimmable PFC DCM flyback converter without the electrolytic capacitor is proposed to prolong the lifetime of the LED driver. For the long lifetime of the converter, the polyester film capacitor with the small capacitance is substituted for the electrolytic capacitor on the output node and an LC resonant filter is added to damp 120Hz ripple current. The proposed converter is verified through the simulation and the experimental works.

• Progress in Superconductivity and Cryogenics
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• 제14권3호
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• pp.43-47
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• 2012

A linear compressor generates pulsating pressure and oscillating flow in a cryocooler such as Stirling cryocooler and pulse tube refrigerator. It is driven by AC power source and designed to operate at resonance of piston motion. The driving voltage level is determined by electric parameters of resistance, inductance and thrust constant of linear motor. From voltage equation on linear motor, the power factor of driving power is inherently less than 1. The phase difference between voltage and current of supplied power can be zero using capacitor and this can minimize a supply voltage level. Especially, the linear compressor of kW class requires high voltage and thus can cause a difficulty in selecting power supply unit due to limitation of voltage level. The capacitor in driving electric circuit is useful to settle this problem. In this study, the electric circuit of linear compressor is analytically investigated with assumption of mechanical resonance. The electric parameters of commercial linear motor are used in the analysis. The effects of capacitor on driving voltage level and power factor are investigated. From analytic results, it is shown that the voltage level can be mimized with using capacitor in driving electric circuit.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제34권7A호
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• pp.568-573
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• 2009

This paper presents a step-down DC-DC converter with On-chip Compensation for battery-operated portable electronic devices which are designed in O.13um CMOS standard process. In an effort to decrease system volume, this paper proposes the on chip compensation circuit using capacitor multiplier method. Capacitor multiplier method can minimize error amplifier's compensation capacitor size by 10%. It allows the compensation block of DC-DC converter be easily integrated on a chip and occupy less layout area. But capacitor multiplier operation reduces DC-DC converter efficiency. As a result, this converter shows maximum efficiency over 87.2% for the output voltage of 1.2V (input voltage : 3.3V), maximum load current 500mA, and 25mA output ripple current. This voltage mode controled buck converter has 1MHz switching frequency.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제62권2호
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• pp.196-200
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• 2013

In this paper, the design of PRT vehicle power supply system is discussed. Since there is no power feeding line facilities in PRT system under development, the PRT vehicle must have its own energy storage device on board. For the energy storage device, ultra-capacitor bank is applied due to its fast charging capability and long life time. Charging the Ultra-capacitor bank is performed by wireless inductive power transfer system. The capacitor bank is charged up in less than 10 seconds when the vehicle is traveling by passenger stations. In this paper the design of the ultra-capacitor bank and the wireless inductive power transfer system for the PRT vehicle are discussed. Tests are conducted for the both system and the result shows the efficiency of the wireless inductive power transfer system is higher than 80%.