• Title/Summary/Keyword: Phase looked loop (PLL)

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An Improved Grid Impedance Estimation using PQ Variations (PQ변동을 이용한 개선된 계통 임피던스 추정기법)

  • Cho, Je-Hee;Kim, Yong-Wook;Kim, Rae-Young
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.2
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    • pp.152-159
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    • 2015
  • In a weak grid condition, the precise grid impedance estimation is essential to guaranteeing the high performance current control and power transfer for a grid-connected inverter. This study proposes a precise estimation method for grid impedance by PQ variations by employing the variation method of reference currents. The operation principle of grid impedance estimation is fully presented, and the negative impact of the phase locked loop is analyzed. Estimation error by a synchronization angle in the park's transformation using the phase locked loop is derived. As a result, the variation method of reference currents for accurate estimation is introduced. The validation of the proposed method is verified through several simulation results and experiments based on a 2-kW voltage source inverter prototype.

Calibration of frequency propagation channel sounder based on five-port reflectometer

  • Yem Van;Braga Judson;Huyart B;Begaud X;de Sousa F.R;Huyen Nguyen Bich
    • Proceedings of the IEEK Conference
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    • summer
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    • pp.23-26
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    • 2004
  • Five-port reflectometer which consists of a ring with 5 arms (two inputs, three outputs) and three RF power detectors has been used as a vector network analyser, a demodulator in the homodyne receiver as well as in Phase Looked Loop (PLL) and so on. Calibration of five-port reflectometer is an important task. In this paper, we present a calibration method of five-port for a propagation channel sounder. The method is based on measurement of the phase differences between the three voltages at the five-port's outputs in order to determine the ratio of two input incident waves. The frequency channel sounder based on five-port is calibrated for each frequency from 2.2 GHz to 2.6 GHz with 1 MHz step. This method can also determine the absolute delays of each propagation path in the propagation channel. The calibration method is validated using measurement data.

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Phase-Locked Loop with a loop filter consisting of a capacitor and a charge pump functioned as resistor (저항 역할을 하는 전하펌프와 하나의 커패시터로 구성된 루프 필터를 가진 위상고정루프)

  • Park, Jong-Youn;Choi, Hyek-Hwan
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.11
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    • pp.2495-2502
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    • 2012
  • This paper presents a new structure of phase looked loop (PLL) for replacing a process sensitive resistor in loop filter with an additional charge pump (CP). The additional charge pump works as a resistor in a loop filter. The output of two charge pumps changes same direction according to process variation. The simulation results according to process conditions(SS/TT/FF) demonstrate that the proposed PLL works properly with process variations. It has been designed with a 1.8V $0.18{\mu}m$ CMOS process and proved by simulation with HSPICE.