• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.8
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• pp.45-51
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• 2008

HID(High Intensity Discharge) search lamp for shipment requires a high open circuit and output current compare than vehicle. This paper presents a soft-start open circuit voltage and constant current sequence control method for 2.5[kW] HID search lamp. The proposed method controls the opal circuit voltage and discharge current of HID lamp according to ignition signal with a simple 8-bit micro-processor and PWM device. For the stable control of lamp, micro-processor checks the output voltage and current. And the checked signals are compared with ignition signal and changes the control mode for stable operation. An ignition signal and micro-processor change the control mode from open circuit voltage contort to constant current control. The proposed control scheme is verified from experimental tests of 2.5[kW] HID search lamp for shipment.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.117-119
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• 2007

본 논문에서는 램프가 한개 이상 개방 시 피드백 제어 회로를 동작하지 않도록 하면서, 램프를 보호할 수 있는 개방전압을 출력하는 LCD 백라이트 구동용 인버터 회로도에 관한 것이다. 램프 개방전압 출력을 위한 회로는 램프 전류 피드백 블록, 개방전압시 이상신호를 감지하는 전압 피드백 블록, 램프 개수에 상관없이 최고치 값을 감지하는 블록으로 되어 있다. 전술한 회로가 내장된 인버터는 램프의 개방 시 램프의 개수 상관없이 CCFL의 보호 스펙인 2500V의 개방전압을 출력한다. 이러한 인버터가 내장된 LCD패널은 향상된 안정화 동작을 구현하게 된다.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.140-142
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• 2004

본 논문에서는 UC3879 PWM 제어기를 사용한 풀브릿지 위상천이 컨버터의 출력전압 피드백 신호선의 개방과 과전압이 발생하였을 경우에 컨버터를 안정적으로 유지시키기 위한 보호 회로를 제안하고 있다.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.234-235
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• 2013

PV cell model은 PV simulator를 제작하거나 시뮬레이션 Software를 통하여 PV 발전시스템을 분석하기 위하여 필요하다. PV cell의 I-V 특성곡선은 PV cell의 특성을 결정짓는 중요한 요소이며, 전기적으로 다이오드정수($I_o$, $v_t$)와 광전류원($I_{ph}$) 그리고 직렬저항($R_s$) 및 션트저항($R_{sh}$)으로 모델링 가능하다. 광 전류원은 일사량에 비례하여 그 값을 추정할 수 있으나 나머지 변수인 다이오드정수($I_o$, $v_t$)와 직렬저항($R_s$) 및 션트저항($R_{sh}$)은 제조사 데이터시트에서 제공하는 3개의 대표적인 운전점인 개방회로 전압($V_{oc}$), 단락회로 전류($I_{sc}$), 그리고 최대출력에서의 전압/전류($V_{MPP}/I_{MPP}$)를 기초로 수학적으로 해를 구하여야만 한다. 본 논문에서는 저자가 제안하는 K-알고리즘의 수학적 도출 과정과 수치해석적 특성을 고찰한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.397-400
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• 2015

In this paper a solar energy harvesting system with low-cost MPPT control for low duty-cycled sensor nodes is proposed. The targeted applications are environment, structure monitoring sensor nodes that are not required successively to operate, and MPPT(Maximum Power point Tracking) control using simple circuits is low-cost differently than existing MPPT control. The proposed MPPT control is implemented using linear relationship between the open-circuit voltage of a solar cell. The designed MPPT circuit traces the maximum power point by sampling periodically the open circuit voltage of the solar cell and delivers the maximum available power to the load. The proposed circuit is designed in 0.35um CMOS process. The designed chip area is $975um{\times}1025um$ including pads. Measured results show that the designed system can track the MPP voltage by sampling periodically the open circuit voltage of solar cell.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.477-480
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• 2015

In this paper a low-voltage vibration energy harvesting circuit with MPPT(Maximum Power Point Tracking) control is proposed. By employing bulk-driven technique, the minimum operating voltage of the proposed circuit is as low as 0.8V. The designed MPPT control circuit traces the maximum power point by periodically sampling the open circuit voltage of a full-wave rectifier circuit connected to the piezoelectric device output and delivers the maximum available power to load. The proposed circuit is designed using a $0.35{\mu}m\;CMOS$ process, and the chip area including pads is $1.33mm{\times}1.31mm$. Simulation results show that the maximum power efficiency of the designed circuit is 85.49%.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.11
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• pp.60-66
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• 2007

In this paper, a novel voltage-controlled oscillator (VCO) using the microstrip square open loop multiple split ring resonator (OLMSRR) is presented for reducing the phase noise property. The square-shaped multiple split ring resonator (MSRR) having the form of the microstrip square open loop is investigated to realize this property. Compared with the microstrip square open loop resonator and the microstrip square open loop split ring resonator (OLSRR) as well as the conventional microstrip line resonator, the microstrip square OLMSRR has the larger coupling coefficient value, which makes a higher Q value, and has reduced the phase noise of VCO. The VCO with 1.7V power suppIy has the phase noise of $-124.5\;{\sim}\;-122.0\;dBc/Hz$ @ 100 kHz in the tuning range, $5.746\;{\sim}\;5.84\;GHz$. The figure of merit (FOM) of this VCO is $-203.96\;{\sim}\;-201.6\;dBc/Hz$ @ 100 kHz in the same tuning range. Compared with VCO using the conventional microstrip line resonator, VCO using the microstrip square open loop resonator and VCO using microstrip square OLSRR, the phase noise property of VCO using the proposed resonator has been improved in 25.66 dB, 8.34 dB, and 4.5 dB, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.12
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• pp.22-27
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• 2007

In this paper, a novel voltage-controlled oscillator (VCO) using the microstrip square open loop split ring resonator (OLSRR) is presented for reducing the phase noise. For this purpose, the square-shaped split ring resonator (SRR) haying the form of the microstrip square open loop is investigated. Compared with the microstrip square open loop resonator, the microstrip square OLSRR has the larger coupling coefficient value, which makes a higher Q value, and has reduced the phase noise of VCO. The VCO with 1.7V power supply has the phase noise of $-120\sim-116.5$ dBc/Hz @ 100 kHz in the tuning range, $5.746\sim5.854$ GHz. The figure of merit (FOM) of this VCO is $-200.33\sim-197$ dBc/Hz @ 100 kHz in the same tuning range.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.11
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• pp.2457-2464
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• 2011

In this paper, a vibration energy harvesting circuit using a piezoelectric device is designed. MPPT(Maximum Power Point Tracking) control function is implemented using the electric power-voltage characteristic of a piezoelectric device to deliver the maximum power to load. The designed MPPT control circuit traces the maximum power point by periodically sampling the open circuit voltage of a full-wave rectifier circuit connected to the piezoelectric device output and delivers the maximum available power to load. The proposed vibration energy harvesting circuit is designed with $0.18{\mu}m$ CMOS process. Simulation results show that the maximum power efficiency of the designed circuit is 91%, and the chip area except pads is $700{\mu}m{\times}730{\mu}m$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.392-395
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• 2011

In this paper, a vibration energy harvesting circuit using the piezoelectric element has been designed. MPPT (maximum power point tracking control) control function has been implemented to deliver the maximum power to the load by using the electric power-voltage characteristic of the piezoelectric element. The designed MPPT circuit traces the maximum power point by sampling periodically the open circuit voltage of the full wave rectifier circuit and delivers the maximum available power to the load. The vibration energy harvesting circuit is designed with $0.18{\mu}m$ CMOS process. The maximum power efficiency is 91%, and the chip area except pads is $1,100{\mu}m{\times}730{\mu}m$.