An Unbalance Mitigation Method based on 3D-SVPWM for Four-Wire Three-Leg Mid Capacitor Point Inverter

The unbalance problem is being as one important issue related to the power quality aspects. Mitigation techniques are also presented to avoid the harmful effects of the unbalance on the power system elements. This paper introduces the unbalance compensator topology based on the 3-phase 4-wire mid capacitor point. The Three Dimensional Space Vector Pulse Width Modulation (3D-SVPWM) is considered an effective tool for dealing with the unbalanced system rather than the Two Dimensional Space Vector Pulse Width Modulation 2D-SVPWM. In this paper, the 3D-SVPWM is based on the planes for determining the tetrahedron rather than using the angle theta. The 3D-SVPWM is based on the d-q-o frame to extract the unbalance current reference. The controller is applied to control the three-phase three-leg mid capacitor point inverter topology. The results show that the controller can restore the system of the unbalanced load to the balance state at the Point of Common Coupling (PCC). Minimization of neutral current with stabilizing the dc voltage is obtained.