A Modular Multilevel T-Type Inverter Based on SVPWM for PV System Application

To find the best multilevel inverter topology structure which is the most suiTable for photovoltaic (PV) distributed grid-connected system, this paper compares the advantages and disadvantages of the three traditional kinds of basic multilevel inverters, and newly emerging topologies are classified according to the basic units which were proposed by predecessors. At the same time, the multilevel grid inverter topology optimization methods and the research trends are summarized. Eventually, the novel T-type inverter topology structure composed of the best two basic units is proposed. The basic principles of the space vector pulse width modulation (SVPWM) and the steps of its digital realization are introduced and established a simulation model reckoning novel T-type structure as the object on the bases of the MATLAB/SIMULINK platform. Results show that it has superiority over the T-type and Clamping diode type three-level circuits (the most widely used topology nowadays) .This structure making full use of the advantages of MOSFET in PV inverter, reduces the harmonic content and common-mode current as well as the power loss of the inverter, and improves the conversion efficiency of the system.