Flatness-Based-Control of Three-phase shunt active power filters based on five-level NPC inverter

The problem of controlling three-phase shunt active power filter (SAPF) is addressed in presence of nonlinear loads. In this paper, a flatness control of three-phase shunt active power filter based on five-level neutral-point-clamped (NPC) inverter is proposed. The control objectives are twofold, the first one consists on compensating the current harmonics and the reactive power absorbed by the nonlinear loads, and the second one concerns the regulation of the inverter DC capacitor voltage. To achieve these objectives, two cascaded loops are designed, an outer loop for the DC voltage regulation, where the inner loop is dedicated for harmonic current compensation. The simulation results are developed under Matlab/Simulink environment to prove the performances of the proposed controller.