Journal of the Optical Society of Korea

  • 제14권3호
  • /
  • Pages.240-244
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  • 2010
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  • 1226-4776(pISSN)
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  • 2093-6885(eISSN)
한국광학회 (Optical Society of Korea)
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Current-induced Phase Demodulation Using a PWM Sampling for a Fiber-optic CT

  • Park, Hyoung-Jun (Advanced Graduate Education Center of Jeonbuk for Electronics and Information Technology-BK21, Chonbuk National University) ;
  • Lee, June-Ho (Department of Electrical Engineering, Hoseo University) ;
  • Kim, Hyun-Jin (Division of Eletronics Engineering, Chonbuk National University) ;
  • Song, Min-Ho (Division of Eletronics Engineering, Chonbuk National University)
  • 투고 : 2010.05.11
  • 심사 : 2010.06.24
  • 발행 : 2010.09.25
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초록

In this work, we used PWM sampling for demodulation of a fiber-optic interferometric current transformer. The interference signal from a fiber-optic CT is sampled with PWM triggers that produce a 90-degree phase difference between two consecutively sampled signals. The current-induced phase is extracted by applying an arctangent demodulation and a phase unwrapping algorithm to the sampled signals. From experiments using the proposed demodulation, we obtained phase measurement accuracy and a linearity error, in AC current measurements, of ~2.35 mrad and 0.18%, respectively. The accuracy of the proposed method was compared with that of a lock-in amplifier demodulation, which showed only 0.36% difference. To compare the birefringence effects of different fiber-optic sensor coils, a flint glass fiber and a standard single-mode fiber were used under the same conditions. The flint glass fiber coil with a Faraday rotator mirror showed the best performance. Because of the simple hardware structure and signal processing, the proposed demodulation would be suitable for low-cost over-current monitoring in high voltage power systems.

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참고문헌

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