Stability issues of current controllers based on repetitive-based control and second order generalized integrators for active power filters

Starting from previous works, this paper analyzes the robustness and stability of two current controller schemes for shunt active power filters, based on repetitive controllers and proportional+resonant controllers using second order generalized integrators connected in parallel. Both controllers are well suited due to their optimum tracking and harmonic rejection capability. The objectives of this paper are: to present a brief description of both controllers, study their behavior under drifts in the value of the plant parameters and in the frequency, and also analyze the suitability of these controllers to work in a current control scheme when a nonlinear load is demanding asymmetric currents. Finally, some comparative results will be shown.