Voltage Regulator using Low Temperature Poly Silicon Technology for TFT-LCD Panel

Takahiko Mizuno,Masahiro Yoshida,Shigeki Imai,Yasoji Suzuki,Shinichi Murata 대한전자공학회 2009 ITC-CSCC :International Technical Conference on Ci Vol.2009 No.7

In this paper, a voltage regulator which can be integrated on a LCD panel using LTPS-TFT is proposed. The new voltage regulator can be reduced the deviation rate of the reference voltage (α') depending on the load fluctuation because the new voltage regulator provides a reference voltage shifter (RVS). By utilizing this circuit configulation, the proposed regulator can be obtained a stable constant output voltage. To confirm some performances of the proposed voltage regulator, the circuit analysis is carried out by using Smart-SPICE. As this results, the regulation rate of the output voltage (α) of the proposed voltage regulator is improved about 50% in comparison with that of conventional circuit under the conditions that the supply voltage (VDD) is +15V, the frequency (f) with the load current of+0.5㎃±0.5㎃ is 250㎑.

An Improvement in Synchronously Rotating Reference Frame-Based Voltage Sag Detection under Distorted Grid Voltages

Sillapawicharn, Yutthachai,Kumsuwan, Yuttana The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.6

This study proposed an improvement in synchronously rotating reference frame-based voltage sag detection under distorted grid voltages. In the past, the conventional synchronously rotating reference frame (CSRRF)-based voltage sag detection was generally used in the voltage sag compensation applications. Its disadvantage is a long delay of detection time. The modified synchronously rotating reference frame (MSRRF)-based voltage sag detection is able to detect the voltage sag with only a short delay in detection time. However, its operation under distorted grid voltage conditions is unavailable. This paper proposed the improvement of modified synchronously rotating reference frame (IMSRRF)-based voltage sag detection for use in distorted grid voltages with very fast operation of voltage sag detection. The operation of the proposed voltage sag detections is investigated via simulations and experimentations to verify the performance of the IMSRRF-based voltage sag detection.

An Improvement in Synchronously Rotating Reference Frame-Based Voltage Sag Detection under Distorted Grid Voltages

Yutthachai Sillapawicharn,Yuttana Kumsuwan 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.6

This study proposed an improvement in synchronously rotating reference frame-based voltage sag detection under distorted grid voltages. In the past, the conventional synchronously rotating reference frame (CSRRF)-based voltage sag detection was generally used in the voltage sag compensation applications. Its disadvantage is a long delay of detection time. The modified synchronously rotating reference frame (MSRRF)-based voltage sag detection is able to detect the voltage sag with only a short delay in detection time. However, its operation under distorted grid voltage conditions is unavailable. This paper proposed the improvement of modified synchronously rotating reference frame (IMSRRF)-based voltage sag detection for use in distorted grid voltages with very fast operation of voltage sag detection. The operation of the proposed voltage sag detections is investigated via simulations and experimentations to verify the performance of the IMSRRF-based voltage sag detection.

Switching Voltage Modeling and PWM Control in Multilevel Neutral-Point-Clamped Inverter under DC Voltage Imbalance

Nho-Van Nguyen,Tam-Khanh Tu Nguyen,Hong-Hee Lee 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2

This paper presents a novel switching voltage model and an offset-based pulse width modulation (PWM) scheme for multilevel inverters with unbalanced DC sources. The switching voltage model under a DC voltage imbalance will be formulated in general form for multilevel neutral-point-clamped topologies. Analysis of the reference switching voltages from active and non-active switching voltage components in abc coordinates can enable voltage implementation for an unbalanced DC-source condition. Offset voltage is introduced as an indispensable variable in the switching voltage model for multilevel voltage-source inverters. The PWM performance is controlled through the design of two offset components in a subsequence. One main offset may refer to the common mode voltage, and the other offset restricts its effect on the quality of PWM control in related DC levels. The PWM quality can be improved as the switching loss is reduced in a discontinuous PWM mode by setting the local offset, which is related to the load currents. The validity of the proposed algorithm is verified by experimental results.

A Single-Stage Resonant Buck-Boost AC Voltage Regulator

Chien-Ming Wang,Chang-Hua Lin,Guan-Yu Chen 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper proposed a single-stage resonant buck-boost ac voltage regulator. The proposed regulator can output a voltage which is larger or lower than the input ac one and is dependence on depending on the instantaneous duty-ratio. This property is not found in the conventional single-stage ac voltage regulator that the ac output instantaneous voltage is always lower than the input ac voltage. The proposed ac voltage regulator uses a series-resonant circuit to configure adaptively the resonant voltage pulse trains. The proposed ac voltage synthesized the resonant voltage pulse trains following the input voltage amplitude to the synthesized sinusoidal waveform (SSW) before output filter. Because the SSW very closes sinusoidal waveform, the proposed ac voltage regulator can use a simple LC filter to filter the undesired harmonics and to get the sinusoidal voltage waveform with low total harmonic distortion (THD). The proposed ac voltage regulator is controlled by constant frequency pulse width modulation technique. Its control circuit is simple. A design example of a 600W proposed ac voltage regulator is examined to assess the system performance. Under rated output power, the power efficiency is over 91% and the total harmonic distortion (THD) is within 6%.

PWM 전압형 인버터의 저전압 출력 정도 개선

이주석 ( Ju-suk Lee ) 한국고등직업교육학회 2004 한국고등직업교육학회논문집 Vol.5 No.1

The speed-and-voltage sensorless drive for the low-speed region of an AC motor using a PWM voltage-fed invertor produces a drop of control accuracy or system unstability, which is caused by the error between command voltage and output voltage of the PWM voltage-fed invertor. This paper presents the causes of this voltage error, that is, quantization error, forward voltage of a switching device and dead time, and suggests their compensations. First, the alternative to quantization error is based on phase voltage and line voltage, and that to forward voltage is feedforward compensation for drop voltage previously measured. The voltage error by dead time is substituted by feedforward in the way of analysing the switching pattern. The experimental studies which apply the above proposals to the induction of speed open loop control system show the improved drive characteristics in the low speed region.

계통연계형 태양광 인버터의 저전압 계통연계 유지조건을 만족하기 위한 알고리즘

황의선(Uiseon Hwang),강문성(Moonsung Kang),양오(Oh Yang) 한국정보기술학회 2014 한국정보기술학회논문지 Vol.12 No.1

The grid connected PV inverter has to maintain connected operation to assure stability and reliability of the grid despite low voltage. But if the grid voltage is sagged in a moment, the PV inverter will stop operating by generating the over current, which is not satisfied with the LVRT. Therefore, this paper proposed the grid voltage compensator to prevent over current And while the grid voltage maintain low voltage, the LVRT algorithm is suggested for stable operation and voltage recovery. When the grid voltage is sagged, the proposed grid voltage compensator analyze fluctuation rate of the grid voltage and control PWM of the PV inverter. The LVRT algorithm fixed level of the output current and generated reactive power to recover voltage at the low voltage. As a result, when the grid voltage is recovered, the inverter satisfied the LVRT by generating active power of over 80% within 0.05s.

문턱전압 폐곡선을 이용한 AC PDP에서 인가전압에 의한 기입방전 특성의 연구

박승섭(Seung Seob Park),조병권(Byung-Gwon Cho) 한국정보기술학회 2020 한국정보기술학회논문지 Vol.18 No.2

The characteristics of the write discharge in the AC plasma display panel are determined by the sum of the wall voltage and the applied voltage formed inside the cell. If the applied voltage is increased under the high wall voltage condition, since the voltage is higher than the total voltage at which the discharge is generated in the cell, the misfiring discharge occurs in the unwanted cell. Therefore, as the total voltage generated inside the cell should be the same, the method of reducing the wall voltage and increasing the applied voltage is proposed. In this study, the write discharge characteristics of the applied voltage when the applied voltage was lower than the wall voltage and high were measured. The applied and the wall voltages were measured using the threshold voltage closed curve. As a result, the write discharge time can be shortened from 1.5 to 1.15μs when the applied voltage is higher than the wall voltage.

Three-Phase PWM-Switched Autotransformer Voltage-Sag Compensator Based on Phase AngleAnalysis

Muhamad Mansor,Nasrudin Abd. Rahim 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.6

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.

동적전압보상기의 전압제어를 위한 PLL 방식의 개선

김병섭(Byong-Seob Kim),최종우(Jong-Woo Choi) 대한전기학회 2009 전기학회논문지 Vol.58 No.5

Dynamic voltage restorer (DVR) is now more preferable enhancement than other power quality enhancement in industry to reduce the impact of voltage faults, especially voltage sags to sensitive loads. The main controllers for DVR consists of PLL(phase locked loop), compensation voltage calculator and voltage compensator. PLL detects the voltage faults and phase. Compensation voltage calculator calculates the reference voltage from the source voltage and phase. With calculated compensation voltage from PLL, voltage compensator restores the source voltage. If PLL detect ideal phase, compensation voltage calculator calculates ideal compensation voltage. Therefore, PLL for DVR is very important. This paper proposes the new method of PLL in DVR. First, the power circuit of DVR system is analyzed in order to compensate the voltage sags. Based on the analysis, new PLL for improving transient response of DVR is proposed. The proposed method uses band rejection filter (BRF) at q-axis in synchronous flame. In order to calculate compensation voltage in commercial instruments, the PQR theory is used. Proposed PLL method is demonstrated through simulation using Matlab-Simulink and experiment, and by checking load voltage, confirms operation of the DVR.