Sliding mode control of three-phase four-wire shunt active power filter

This paper presents a sliding mode based control strategy applied to a 3-phase 4-wire split-capacitor active power filter. The filter is aimed to compensate reactive power and harmonic distortion in the case of distorted and unbalanced load currents. The sliding mode controller is designed utilizing the systempsilas multivariable state space model in the synchronous dq0 reference frame. The sliding mode switching functions are constructed in such a way that the compensation currents track their references, and simultaneously, the two DC capacitor voltages are regulated and equalized. The stability of the closed loop system is guaranteed according to Lyapunov stability criterion. In this paper, an analytical study and verification by digital simulation are conducted.