The Journal of Korean Institute of Electromagnetic Engineering and Science (한국전자파학회논문지)

The Korean Institute of Electromagnetic Engineering and Science (한국전자파학회)
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Performance Improvement Using Real-Time Detection of Time-Variant Load Impedance of the Receiver in Wireless Power Transfer System

시간에 따라 변하는 수신단 부하 임피던스의 실시간 검출을 통한 무선 전력 전송시스템의 성능 개선

  • 장형석 (한국과학기술원 전기 및 전자공학과) ;
  • 태현성 (한국과학기술원 전기 및 전자공학과) ;
  • 김광석 (한국과학기술원 전기 및 전자공학과) ;
  • 여태동 (한국과학기술원 전기 및 전자공학과) ;
  • 오경섭 (한국과학기술원 전기 및 전자공학과) ;
  • 유종원 (한국과학기술원 전기 및 전자공학과)
  • Received : 2014.02.04
  • Accepted : 2014.05.12
  • Published : 2014.06.30
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Abstract

In this paper, an analysis of the effect of time-variant reflected impedance and its detection method on wireless power transfer(WPT) systems are presented. The reflected resistance at WPT systems is very important parameter as it indicates how well matched antenna is and will exhibit high efficiency. Proposed detection method is based on transmitter current variation analysis with respect to frequency sweep. Using the proposed design method, a wireless power transfer system operating at the frequency of 125 kHz, is design and detect reflected impedance variation. The proposed design method provides good agreements between measured and simulated results. Therefore, The proposed detecting method provides a nonintrusive method to detect harmful object in WPT system.

본 논문에서는 무선 전력 전송 시스템에서 시간에 따라 변하는 반사 임피던스(reflected impedance)가 시스템에 주는 영향을 분석하고, 그 검출 방법을 제안하였다. 반사 임피던스는 송신기와 결합하는 수신기가 어떠한 특성을 가지는지를 나타내는 중요한 지표가 되며, 전송 효율에 큰 영향을 주게 된다. 반사 임피던스를 검출하기 위해서 주파수에 따른 송신기에 흐르는 전류의 변화를 분석하는 검출 방법을 제안하였다. 본 논문에서 제시한 설계 방법에 따라 LF 대역에서 동작하는 무선 송/수신시스템을 설계하고, 수신기의 반사 임피던스의 변화를 검출하였다. 측정 결과, 제안한 검출 방법이 반사 임피던스를 정확하게 측정할 수 있음을 확인하였다. 실제 배터리에 적용하여 absorption mode에서 시간에 따라 증가하는 부하 임피던스로 인한 효율 감소를 보정할 수 있음을 실험을 통해 검증하였다. 또한, 금속 인식 시스템도 구현하여 제안한 측정법의 유용성을 확인하였다.

Keywords

References

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