Nonlinear adaptive control of single phase half bridge shunt active power filter

The problem of controlling single-phase half bridge shunt active power filter (HBSAPF) is addressed in this paper in presence of nonlinear loads of rectifier type. The control objective is twofold: (i) compensation of harmonic currents and the reactive power absorbed by the nonlinear load; (ii) regulation the DC bus voltage of the inverter. First an adaptive observer is designed to estimate the network voltage which is not accessible to measurement and the unknown parameters of the network internal impedance. Second, a nonlinear controller that involves two loops in cascade, an inner-loop is designed, using the Lyapunov approach, to provide the harmonic compensation and an outer-loop is designed to regulate the DC bus voltage of the inverter. The controller performances are illustrated by simulation in Matlab/Simulink environment.