Input-Output Linearization Control of an LCL Filter Employing a Symmetric Geometry in Grid-Connected Inverter Applications

D.-H. Ha, K.-J. Lee, R.-Y. Kim, and D.-S. Hyun (Korea)


LCL filter, Input-output linearization, Modelling,Decoupling, Grid-connected inverter


An inductor-capacitor-inductor (LCL) filter is widely adapted in grid-connected inverter applications. In this paper, the harmonic attenuations of the LCL filter are quantitatively analyzed, and then the design optimization of two inductance values, which are related on a cost and a size, is illustrated. Based on the design optimization, the LCL Filter employing a Symmetric Geometry is proposed. Through the equivalent circuit analysis of the proposed LCL filter, the operating characteristics and validity are presented in detail. Furthermore, a state variable decoupling controller by input-output linearization is designed to mitigate the resonance problem. From simulation results, it is seen that the proposed LCL filter and control method have a sufficient attenuation and stability for the grid voltage distortions.

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