Sliding mode control of 3-phase 3-wire shunt active filter in the dq frame

In this paper a sliding mode approach is developed to control a three-phase three-wire voltage source inverter operating as a shunt active power filter. The novelty of the proposed approach is that the sliding mode switching functions are chosen in such a way that the multivariable coupled system is controlled as a whole. There is hence no need to divide the system model, which is developed in the synchronous 'dq' reference frame into two separate loops. Furthermore the proposed control strategy allows a better stability and robustness over a wide range of operation. Simulation results show the validity of the performances considered theoretically for the compensations required by the shunt active filter.