Series-connected T-type Inverters for single-phase grid-connected Photovoltaic Energy System

This paper presents a new small-scale single-phase photovoltaic (PV) energy conversion system. The topology is based on the series connection of two three-level T-type converters, which form a 5-level converter with two independent maximum power point tracking (MPPT) string connections. The topology merges benefits of string and multi-string PV configurations. The operating principle, the switching states, modulation scheme and control method are addressed in the paper. Simulation results are presented under dynamic conditions and different operating points for the two PV strings, to provide a preliminary validation of the topology and its performance.