• 한국자동차공학회논문집
• /
• 제14권6호
• /
• pp.24-33
• /
• 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.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 추계종합학술대회 논문집(2)
• /
• pp.333-336
• /
• 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.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 하계학술대회 논문집
• /
• pp.675-678
• /
• 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 %.

• 조명전기설비학회논문지
• /
• 제22권9호
• /
• pp.94-102
• /
• 2008

대전 관내에서 송전계통 및 배전계통의 고장발생이 없었음에도 불구하고 고압 수용가의 2차측에서 플리커(형광등 깜박거림), 엘리베이터 정지 등의 문제가 수차례 발생하였다. 순간 전압변동의 원인을 해당 변전소 캐패시터 소손, 캐패시터 투입과 OLTC 조작으로 인한 전압변동, 고조파 공진 등을 원인으로 추정하고 같은 전압변동 원인 분석을 실시하였다. 분석 개소는 정전이 발생된 변전소 모선 전압과 전류, 캐패시터 뱅크의 전압과 전류, 덕진과 항공 D/L의 전류, 세종아파트의 MOF와 엘리베이터 전용의 변압기 2차측의 전압과 전류이다. 분석결과 변전소의 캐패시터 뱅크의 콘덴서, 리액터, 방전코일의 조사 결과 열화 및 소손이 없었으며, 4차 고조파에 공진이 되도록 설정된 것도 측정을 통해 이상 없음을 확인하였다. 사고재현을 위해 이전과 동일하게 변전소 캐패시터 조작을 수행했으나 엘리베이터가 중단되는 현상이 재현되지 않았지만 고압측의 콘덴서를 투입하였을 때 수용가측의 저압변압기 2차측에서 15[%] 이상 전압이 확대됨을 확인하였다. 다양한 분석과 시뮬레이션 결과 공진에 의해 전압이 확대되었음을 규명하였다.

• 기술사
• /
• 제33권1호
• /
• pp.94-105
• /
• 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.

• 전력전자학회논문지
• /
• 제26권4호
• /
• pp.277-284
• /
• 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.

• 전기학회논문지P
• /
• 제65권4호
• /
• pp.285-291
• /
• 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.

• 한국초전도ㆍ저온공학회논문지
• /
• 제14권3호
• /
• pp.43-47
• /
• 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.

• 한국통신학회논문지
• /
• 제34권7A호
• /
• pp.568-573
• /
• 2009

본 논문에서 0.13um CMOS 공정으로 설계된 배터리 기반 휴대용 통신 시스템 구동용의 온칩 시동회로를 갖는 스텝다운 CMOS DC-DC 변환기를 제안하였다. 1MHz의 스위칭 주파수를 기반으로 설계된 벅 변환기에는 온칩 시동회로와 커패시터 멀티플라이어 기법을 이용한 보상회로를 포함시켰다. 칩 측정 결과 2.5V ${\sim}$3.3V의 입력 전압을 1.2V로 강압시키는데 최대 87.2%의 효율을 갖는다. 최대 부하 전류, 출력 전류 리플 및 전압 리플은 각각 500mA, 25mA, 24mV 이다.

• 전기학회논문지
• /
• 제62권2호
• /
• pp.196-200
• /
• 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%.