Active Damping Characteristics on Virtual Series Resistances of LCL Filter for Three-phase Grid-connected Inverter

인덕터 내부저항을 고려한 LCL 필터의 능동댐핑 특성

Kim, Yong-Jung;Kim, Hyosung

  • Received : 2015.10.21
  • Accepted : 2015.12.28
  • Published : 2016.02.20


LCL filters are widely used in high-order harmonics attenuation of output currents in grid-connected inverters. However, output currents of grid-connected inverters with LCL filters can become unstable because of the resonance of the filters. Given that the characteristics of output currents in inverters mostly depend on filter performance, the exact analysis of filters by considering parasitic components is necessary for both harmonics attenuation and current control. LCL filters have three or four parasitic components: the series and/or parallel resistance of the filter capacitor and the series resistance of the two filter inductors. Most studies on LCL filters have focused on the parasitic components of the filter capacitor. Although several studies have addressed the parasitic components of the filter inductor at the inverter side, no study has yet investigated the concurrent effects of series resistance in both filter inductors in detail. This paper analyzes LCL filters by considering series resistance in both filter inductors; it proposes an active damping method based on the virtual series resistance of LCL filters. The performance of the proposed active damping is then verified through both simulation and experiment using Hardware-in-the-Loop Simulator(HILS).


Grid-connected inverter;LCL filter;Active damping;Series resistance of filter inductor


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