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A Non-Iterative Design Method for Output LCL Filter with RC Damping in Grid-Connected Inverters
  • Bishal Mondal ,
  • Arun Karuppaswamy B
Bishal Mondal
Indian Institute of Technology Madras, Indian Institute of Technology Madras

Corresponding Author:[email protected]

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Arun Karuppaswamy B
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LCL filters with passive damping are widely used for grid-connected inverter (GCI) applications. This work proposes a novel non-iterative component selection procedure for the LCL filter with passive RC damping. While the primary goal of the filter is to effectively attenuate the switching frequency components of the inverter, there are several other desirable constraints that make the selection procedure challenging. In this work, eight such desirable constraints are identified from the existing literature and the proposed method meets all the identified constraints. Besides being non-iterative, the novelty of the work primarily lies in the selection of the damping resistor Rd and the ratio n in which the total shunt capacitor is split. The primary intent of Rd being to damp the resonance, a methodical approach that ensures a high impact of the resistance at the resonance frequency is proposed. The proposed approach also ascertains a minimum possible quality factor. The selection of the ratio n is leveraged as an additional degree of freedom. An analytical method to find the range for n that offers a critically flat resonance peak is proposed. A critically flat resonance peak is important for control stability. The final value of n is chosen from the available range to meet all the constraints.