• Journal of Power Electronics
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• 제15권3호
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• pp.695-701
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• 2015

Uninterruptible Power Supplies (UPSs) can be largely divided into the passive-standby, line-interactive and double-conversion methods. This paper proposes a double-conversion UPS with a low cost and high performance. This single phase UPS uses a single-loop robust voltage controller and 1-switch voltage doubler strategy PFC. The proposed UPS is composed of a single phase PFC, a half-bridge inverter, a battery charger and a battery discharger. Finally, the validity of proposed UPS was verified by various experimental tests.

• 전기학회논문지P
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• 제53권3호
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• pp.148-151
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• 2004

For turn on high pressure sodium vapor lamp, Starting Voltage is very important factor. This starting voltage supply to high pressure sodium vapor lamp as electric discharge lamp, Electric field is producted in electric discharge tube, So accelerative electron collide against vapor atom and second electron is generated, And rapidly the current flow to electric discharge tube. This starting voltage is high voltage and source for melting contact that relay is according as turn on/off high pressure sodium vapor lamp. Consequently, This paper propose that the prevention of melting contact in accordance relay of controller for turn on/off high pressure sodium vapor lamp.

• 한국정보통신학회논문지
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• 제11권8호
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• pp.1552-1557
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• 2007

본 논문에서는 밴드갭 기준전압을 이용하여 동작온도에 무관한 PWM(Pulse Width Modulation) 제어 회로를 설계 하였다. 동작온도에 무관한 PWM 제어기는 BiCMOS 기술을 이용하여 동작온도에 무관한 기준전압과 동작온도에 따라 변화하는 두개의 기준 전압을 이용하였다. 설계되어진 회로는 공급전압 3.3volt를 사용하였으며, 출력 주파수는 1MHz이다. 회로의 시뮬레이션 결과 동작 온도가 $0^{\circ}C$에서 $70^{\circ}C$까지 변화할 때, PWM 제어기의 출력 펄스폭의 변화는 상온에 비하여 +0.86%에서 -0.38%였다.

• Journal of Power Electronics
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• 제11권6호
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• pp.897-903
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• 2011

Many voltage sag compensators have been introduced, including the traditional dynamic voltage restorer (DVR), which requires an energy storage device but is inadequate for compensating deep and long-duration voltage sags. The AC-AC sag compensators introduced next do not require a storage device and they are capable of compensating voltage sags. This type of compensator needs an AC-AC converter to regulate the output voltage. Presented in this paper is a three-phase PWM-switched autotransformer voltage sag compensator based on an AC-AC converter that uses a proposed detection technique and PWM voltage control as a controller. Its effectiveness and capability in instantly detecting and compensating voltage sags were verified via MATLAB/Simulink simulations and further investigated through a laboratory prototype developed with a TMS320F2812 DSP as the main controller.

• 조명전기설비학회논문지
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• 제21권8호
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• pp.136-143
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• 2007

개선된 지령치 변경부를 가지는 전류제어기는 과도 상태에서의 빠른 응답성과 정상 상태에서의 고정밀도를 가진다. 이 논문에서는 개선된 지령치 변경부가 빠른 과도 응답성을 위하여 동기 PI 제어기를 사용하였다. 전류 제어기의 과도 응답특성은 DC 링크 제어 전압의 부족으로 인해 높은 역기전력 영역에서 많은 문제를 가지고 있다. 이 논문은 지령 전압과 한계 전압을 가지는 개선된 지령치 변경부를 제안하였다.

• 한국태양에너지학회 논문집
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• 제34권2호
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• pp.1-7
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• 2014

Generally, buck converter controller is designed to control the output voltage of the converter. However, design of the controller in a photovoltaic power conditioning system is different from theoretical design guideline. The controller in a photovoltaic power conditioning system controls the input voltage of the converter (the output voltage of the solar cell) to meet a maximum power point tracking (MPPT) performance. In this study, a new model for buck converter used in a photovoltaic power conditioning system is proposed, which is linearized after state-space averaging in each period. Also, mathematical expression of the modeled buck converter is interpreted separately as small and large signals; therefore its appropriateness is measured to design linear voltage and current controller.

• Journal of Electrical Engineering and Technology
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• 제4권3호
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• pp.330-336
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• 2009

This paper proposes an on-line voltage management and control solution for a distribution system which can improve the efficiency and accuracy of existing off-line work by collecting customer voltage on-line as well as the voltage compensation capability of the existing ULTC (Under Load Tap Changer) operation and control strategy by controlling the ULTC tap based on pattern clustering and recognition. The proposed solution consists of an ADVMD (Advanced Digital Voltage Management Device), a VMS (Voltage Management Solution) and an OLDUC (On-Line Digital ULTC Controller). An on-line voltage management emulator based on multi-thread programming and the shared memory method is developed to emulate on-line voltage management and digital ULTC control methodology based on the on-line collection of the customer's voltage. In addition, using this emulator, the effectiveness of the proposed pattern clustering and recognition based ULTC control strategy is proven for the worst voltage environments for three days.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1635-1645
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• 2015

This study proposes high-performance voltage controller design that employs a capacitor current control model for single-phase stand-alone inverters. The single-phase stand-alone inverter is analyzed via modeling, which is then used to design the controller. A design methodology is proposed to maximize the bandwidth of the feedback controller. Subsequently, to compensate for the problems caused by the bandwidth limitations of the controller, an error transfer function that includes the feedback controller is derived, and the stability of the repetitive control scheme is evaluated using the error transfer function. The digital repetitive controller is then implemented. The simulation and experimental results show that the performance of the proposed controller is high in a 1.5 kW single-phase stand-alone inverter prototype.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.673-675
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• 2004

This study proposes controller with voltage-compensated drivers for producing gray-scaled pictures on passive matrix organic light emitting diodes (PMOLEDs) panels. The controller includes voltage type drivers so the output impedance of the driver is far less than that of the current-type driver. Its low output impedance provides better electron-optical properties than those of traditional current drivers. A free running clock and a group of counters are applied to the gray-scaled function so that phase lock loop (PLL) circuit can be reduced in the controller. A pre-charge function is used to enhance performance of the luminance of an active OLED pixel. As a result, distribution of the low gray level portion is achieved linear relationship with input data. In this work, the digital part of the proposed controller is implemented using FPGA chips, and analog parts are combined with a digital-analog converter (DAC) and analog switches. A still image is displayed on a $48^{\ast}64$ PMOLEDs panel to assess the luminance performance fir the controller. Based on its cost requirement and luminance performance, the controller is qualified to join the market for driving PMOLEDs panels.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1056-1058
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• 1998

Voltage dips caused by transmission system faults are usually of a short duration. High speed relaying and breaker operation will typically limit the disturbance to 0.1 seconds. Most motor controllers obtain their control power directly from the bus by means of a control transformer. Under this condition, a voltage dip can cause the contactor to drop out. disconnecting the motor from the line. The rapid re-energizing of the controller is in effect a fast reclosure which may result in motor damage. The time delay re-energizing of controller will result in a greater loss of speed and possibly loss of stability. Other means of controller can be used to prevent the motor from being disconnected from line during the fault. This can be accomplished by DC power controller or mechanically latched controller. This paper demonstrates that DC power controller or mechanically latched type controller to prevent the motor from being disconnected from line during the fault is, the most effective in minimizing speed reduction, transient motor current, transient motor torque and transient shaft torque by EMTP calculation.