H∞ robust control with application for active power filters

This paper investigates the use of robust H
_∞
controllers to generate the output voltage of PWM inverter such that the grid currents present a low harmonic content in active power filter applications. The grid inductance is considered as an uncertain parameter, what poses a more challenging design scenario. The nonlinear load must be modeled as a disturbance and the controller is capable to attenuate harmonics from the load current to the output current, being suitable for this class of applications. The results show that a robust H
_∞
controller synthesized with a norm limitation in the control gain can ensure good performance and that a conventional controller (non-robust) cannot ensure stability against grid uncertainties.