• Journal of Power Electronics
• /
• 제13권2호
• /
• pp.313-321
• /
• 2013

This paper describes the operation analysis results of a communication-based DC micro-grid using a hardware simulator developed in the lab. The developed hardware simulator is composed of distributed generation devices such as wind power, photovoltaic power and fuel cells, and energy storage devices such as super-capacitors and batteries. Whole system monitoring and control was implemented using a personal computer. The power management scheme was implemented in a main controller based on a TMS320F28335 chip. The main controller is connected with the local controller in each of the distributed generator and energy storage devices through the communication link based on a CAN or an IEC61850. The operation analysis results using the developed hardware simulator confirm the ability of the DC micro-grid to supply the electric power to end users.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.721-722
• /
• 2008

This paper deals with comparison and analysis for rotor losses of permanent magnet synchronous generator using phase current harmonic analysis according to dc and ac load. On the basis of analytical field analysis, the rotor losses are analysed. Particularly, rated speed and ac load and the rated speed and dc load conditions are considered. This paper compared rotor losses considered dc load with rotor losses considered ac load. Although our analytical modes is low speed, the rotor losses must be considered by results.

• Journal of international Conference on Electrical Machines and Systems
• /
• 제1권1호
• /
• pp.121-127
• /
• 2012

An electric power compensation system for a DC transmission system with an integrated wind turbine generator is proposed. The proposed compensation system consists of a synchronous generator and a duplex reactor. This apparatus is connected to the sending-end circuit of the DC transmission system. A set of steady-state equations of the system is first derived. Then, the effect of the duplex reactor, which can eliminate the sending-end grid current distortion due to commutation of the converter, is explored. The relationships among power at the sending-end circuit are also revealed. It is shown that fluctuations in the sending-end grid power due to changes in wind velocities are compensated with the proposed system. Finally, the effects of the sending-end grid conditions on the steady-state characteristics of the system are studied.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.1116-1117
• /
• 2007

In this paper, the control method of maximum power point tracking (MPPT) using the duty ratio control of buck-type dc/dc converter is presented for seaflow generation system. The advantage of the proposed MPPT method is that characteristics of seaflow generator(SG) with respect to seaflow speed, required in the conventional MPPT method, are not needed. Also, due to using the SG output power as a control parameter, neither characteristics of the seaflow speed nor measurements of the rotational speed of the generator are required. Thus, there are advantages that seaflow generation system having features of lower cost and complexity, and higher reliability can be designed. In this paper, Seaflow generation system using the buck-type dc/dc converter is proposed and the effectiveness of the MPPT algorithm is confirmed by matlab simulink.

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2018년도 공동국제학술발표회
• /
• pp.175-175
• /
• 2018

• 한국전자파학회논문지
• /
• 제26권9호
• /
• pp.798-805
• /
• 2015

본 논문에서는 랜덤 수 생성 회로를 통해 Relaxation Oscillator의 주파수를 불규칙하게 변환하여 EMI Noise를 최소화하는 방법을 제시한다. 또한, DC-DC Converter에 이 기법이 적용되었을 때의 효과와 이 결과가 RF Receiver system에 미치는 효과를 Noise 측면에서 연구하였다. 제안하는 Relaxation Oscillator 출력 중심주파수는 7.9 MHz이고, 온도보상기법을 적용하여 온도변화에 따라 주파수가 보상되도록 설계하였다. 이 칩은 $0.18{\mu}m$ 공정으로 설계하였고, 칩의 면적은 $220{\mu}m{\times}280{\mu}m$이다. 전류 소모는 공급전압인 1.8 V에서 $500{\mu}A$이다.

• Journal of Power Electronics
• /
• 제11권2호
• /
• pp.188-193
• /
• 2011

A highly efficient AC-DC converter for small wind power generation systems using a brushless DC generator (BLDCG) is presented in this paper. The market standard AC-DC converter for a BLDCG consists of a three-phase diode rectifier and a boost DC-DC converter, which has an IGBT and a fast recovery diode (FRD). This kind of two-stage solution basically suffers from a large amount of conduction loss and the efficiency greatly decreases under a light load, or at a low current, because of the switching devices with a P-N junction. In order to overcome this low efficiency, especially at a low current, a three-phase bridgcless converter consisting of three upper side FRDs and three lower side Super Junction FETs is presented. In the overall operating speed region, including the cut-in speed, the efficiency of the proposed converter is improved by up to 99%. Such a remarkable result is validated and compared with conventional solutions by calculating the power loss based on I-V curves and the switching loss data of the adopted commercial switches and the current waveforms obtained through PSIM simulations.

• 전기전자학회논문지
• /
• 제12권3호
• /
• pp.176-183
• /
• 2008

본 논문에서는 DTMOS(Dynamic Threshold voltage MOSFET) 스위칭 소자를 사용한 고 효율 전원 제어 장치 (PMIC)를 제안하였다. 높은 출력 전류에서 고 전력 효율을 얻기 위하여 PWM(Pulse Width Modulation) 제어 방식을 사용하여 PMIC를 구현하였으며, 낮은 온 저항을 갖는 DTMOS를 설계하여 도통 손실을 감소시켰다. 벅 컨버터(Buck converter) 제어 회로는 PWM 제어회로로 되어 있으며, 삼각파 발생기(Saw-tooth generator), 밴드갭기준 전압 회로(Band-gap reference circuit), 오차 증폭기(Error amplifier), 비교기(Comparator circuit)가 하나의 블록으로 구성되어 있다. 삼각파 발생기는 그라운드부터 전원 전압(Vdd:3.3V)까지 출력 진폭 범위를 갖는 1.2MHz 발진 주파수를 가지며, 비교기는 2단 연산 증폭기로 설계되었다. 그리고 오차 증폭기는 70dB의 DC gain과 $64^{\circ}$ 위상 여유를 갖도록 설계하였다. Voltage-mode PWM 제어 회로와 낮은 온 저항을 스위칭 소자로 사용하여 구현한 DC-DC converter는 100mA 출력 전류에서 95%의 효율을 구현하였으며, 1mA이하의 대기모드에서도 높은 효율을 구현하기 위하여 LDO를 설계하였다.

• 한국정보통신학회논문지
• /
• 제16권10호
• /
• pp.2237-2246
• /
• 2012

본 논문에서는 구강센서를 소형화하고 제조 원가를 낮추기 위해 구강센서에서 필요로 하는 바이어스 회로를 구강센서 칩 내부에서 만들어주었다. 제안된 DC-DC 변환기 회로는 기준전류 발생기(reference current generator) 회로의 IREF를 이용하여 전압 레귤레이터(voltage regulator)에 필요한 기준전류와 바이어스 전류를 각각 공급해준다. 이들 전류가 각각의 전압 레귤레이 회로에서 해당되는 기준전압을 생성하여 부궤환(negative feedback)에 의해 목표전압을 regulation하게 된다. 그리고 기준전류가 전류 복사비(current mirror ratio)에 의해 mirroring되어 정전류인 IB0/IB1을 공급해주고, VREF 전압을 공급해주도록 설계하였다. $0.18{\mu}m$ X-ray CMOS 이미지 센서 공정을 이용하여 설계된 구강센서의 DC-DC 변환기의 출력 전압의 평균 전압, ${\sigma}$와 $4{\sigma}$는 양호한 측정 결과를 얻었다. 그리고 line-pair pattern 영상은 blurring 없이 높은 해상도 특성을 보였으며, 좋은 구강 영상을 획득하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.1608-1609
• /
• 2011

In this study, in order to develop the evaluation method for XLPE materials for HVDC cables, DC/Impulse superposition testing system was builded up. Throughout the P-spice simulation, optimal values of the protection resistor for the DC generation system and the blocking capacitor for the Impulse generator were calculated. DC/Impulse superposition system showed good result maintaining their proper wave shapes and amplitudes. This system would be planned to apply to the evaluation of XLPE materials for HVDC cables.