A new topology for dynamic voltage restorers without dc link

In this paper, a new topology based on matrix converter (MC) is proposed for dynamic voltage restorer (DVR). Matrix converters convert ac to ac with no dc link. So, applying this type of converters is an acceptable way to eliminate dc link in conventional DVRs. Three independent three-phase to single-phase MCs with 6 or 8 bi-directional power switches are applied in the proposed topology. As a result, the proposed DVR structure can be used to restore load voltage in both balanced and unbalanced voltage sag and swell conditions. The range of the DVR´s correct operation varies selecting 6 or 8 numbered bi-directional power switches in matrix converters. The proposed topology increases the speed and efficiency of DVR and in return decreases the size of DVR, due to the dc link elimination. The proposed DVR can be presented as a package able to compensate voltage sag and swell regardless of the balance or unbalance conditions. Also, one of the most important capabilities of the proposed DVR is the voltage restoring in extremely disturbed networks. The experimental results as well as simulation results in PSCAD/EMTDC environment show that the proposed topology operates correctly and the voltage of sensitive load is completely controlled.