• Title/Summary/Keyword: Trans-less Inverter

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Output Current DC offset Removal Method for Trans-less PV Inverter (무변압기형 태양광 인버터의 출력 전류 DC offset 제거 방법)

  • Hong, Ki-Nam;Choy, Ick;Choi, Ju-Yeop;Lee, Sang-Chul;Lee, Dong-Ha
    • Journal of the Korean Solar Energy Society
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    • v.32 no.spc3
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    • pp.255-261
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    • 2012
  • Since PV PCS uses output current sensor for ac output current control, the sensor's sensing value includes unnecessary offset inevitably. If PV inverter is controlled by the included offset value, it's output current will generate DC offset. The DC offset of output current for trans-less PV inverter is fatal to grid, which results in saturating grid side transformer. Usually DSP controller of PV inverter reads several times sensing value during initial operation and, finally, it's average value is used for offset calibration. However, if temperature changes, the offset changes, too. And also, the switch device is not ideal, both each switching element of the voltage drop difference and on & off time delay difference generate DC offset. Thus, to compensate for deadtime and the switch voltage drop, feedback control by output current DC offset should be provided to compensate additional distortion of the output current. The validity of the proposed method is confirmed through PSIM simulation.

Current Sensor Offset Calibration Method using Dual Sensor for trans-less PV Inverter (듀얼 센서를 이용한 무변압기형 태양광 인버터 전류 센서의 오프셋 보정 방법)

  • Hong, Ki-Nam;Choy, Ick;Choi, Ju-Yeop;Lee, Young-Kwon
    • 한국태양에너지학회:학술대회논문집
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    • 2012.03a
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    • pp.182-187
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    • 2012
  • Since PV PCS uses output current sensor for ac output current control, the sensor's sensing value includes unnecessary offset inevitably. If PV inverter is controlled by the included offset value, it's output current will generate DC offset. The DC offset of output current for trans-less PV inverter is fatal to grid, which results in saturating grid side transformer. Usually DSP controller of PV inverter reads several times sensing value during initial operation and, finally, it's average value is used for offset calibration. However, if temperature changes, the offset changes, too. Therefore, output current sensor measures sensing value that includes offset again. In this paper we propose new algorithm where two identical forward and reverse sensors are used to calculate the offset in real time. As a result the offset is not correlated with temperature change. The proposed algorithm is verified through PSIM simulation for validity.

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The Utility Interaction type PV system by using partial resonant system (부분공진기법을 이용한 연계형 태양광발전시스템)

  • 고강훈;이현우;김영철;최광주
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 1999.11a
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    • pp.290-295
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    • 1999
  • This paper describes Trans-less type utility interactive system that is combined with buck/boost chopper applying partial resonant method, which remove Trans, and high efficient PWM inverter. Therefore, it is possible to make it lightweight, to cut down the cost, and to improve its reliability. What the merits of this system are that we con transmit arbitrary power to load and utility regardless of generating voltage magnitude and we can always obtain high factor controlling by equal phase signal with utility.

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