Improved non-fragile H∞ control on Three-phase Four-leg shunt active power filter

Firstly the period averaging dynamic model of Three-phase Four-leg APF is established based on KVL. In the light of complex control and difficult implementation of dynamic compensation, the nonlinear mathematical model is changed into the standard linear model by reasonable hypothesis. Secondly, aiming at the problem that the APF controller with parameters perturbation has low robust, with the help of LMI, the improved non-fragile H∞ control on three-phase four-leg APF is studied in this paper. Finally, the simulation results are presented to prove that the good compensation effect can obtained with the parameters perturbation. Furthermore the closed-loop APF can remain H∞ index stable.