Delta-Sigma Integral Sliding-Mode Control Strategy of a Three-Phase Active Power Filter Using d-q Frame Theory

A delta-sigma integral sliding-mode (ISM) control strategy applied to an active power filter (APF) is presented. The APF is connected in a parallel (shunt) configuration in order to compensate for reactive power and mitigate harmonic currents. The active filter is applied to a 1 kW, 208 V three-phase front-end rectifier, which is used to supply the required power of a low-voltage, high current DC-power supply, typically ranging between 100-500 A for output current, and 12 V for output voltage. In particular, the new ISM approach is developed to simplify the control of a three-phase PWM voltage source inverter (VSI) employed as the active filter in a three-phase three-wire configuration. Simulation results show the feasibility of the approach to compensate the reactive power, as well as to reduce low-order harmonic currents. Further, a phase portrait and state trajectory diagrams are presented under load variations. Further, experimental results are presented to verify the feasibility of the ISM control strategy