Comparative study of topologies of single phase static converters for grid connected PV systems

The elimination of the transformer of the connection of a PV installation doesn´t only reduce the cost, size and weight, but also improves the efficiency of PV system installation. However, removal of the transformer causes the loss of electrical isolation between the PV generator and the grid. In this paper, a transformer less single-phase single stage grid connected PV system is proposed. A control algorithm for both the maximum extraction of the power and control of current injected into the grid is described. Also, a detailed comparative study of four converters topologies is elaborated showing the interest of the NPC structures against the problem caused by the common mode currents especially in the absence of transformers.