Third harmonic injection on sliding mode control for a three-phase, three-wire inverter

This paper presents an approach to include the third harmonic injection into a Three-Phase, Three-Wire Voltage Sourced Inverter (VSI) operating with sliding mode control. First, independent phase currents are controlled to deliver the primary source power to the grid. Since only two phase current have been controlled, an extra degree of freedom can be employed to include the third harmonic injection. This is done by designing a neutral point voltage surface. Thanks to this, the DC-link voltage utilization is increased by a 13% without losing any advantage of the conventional sliding mode control. This method is conceptually simple and involves few steps. Experiments are carried out to confirm the effectiveness of proposed control algorithms.