On Lossless Negative Imaginary Property for the Characterization of LCL Filters

This paper presents a brief survey of some of the main results in the negative imaginary systems theory and its applications. In particular, the paper concentrates on the application of lossless negative imaginary property for the characterization of the LCL filter, widely used for grid-connected inverters. The characterization is established when the (all possible) LCL filter transfer functions satisfy the lossless negative imaginary conditions. The results are compared with the frequency response of the LCL filter transfer functions.