New Switched-Dual-Source Multilevel Inverter for Symmetrical and Asymmetrical Operation

The increasing integration of large solar PV and wind farms into the power grid has fueled, over the past two decades, growing demands for high-power, high-voltage, utility-scale inverters. Multilevel inverters have emerged as the industry's choice for megawatt-range inverters because of their reduced voltage stress, capability for generating an almost-sinusoidal voltage, built-in redundancy and other benefits. This paper presents a novel switched-source multilevel inverter (SS MLI) architecture. This new inverter shows superior capabilities when compared to existing topologies. It has reduced voltage stress on the semiconductor, uses fewer switches (i.e., reduced size/weight/cost) and exhibits increased efficiency. The proposed SS MLI is comprised of two voltage sources (V-1, V-2) and six switches. It is capable of generating five-level output voltage in symmetric mode (i.e., V-1 = V-2) and seven-level output voltage in asymmetric mode (i.e., V-1 not equal V-2). We present simulations results (using MATLAB (R)/Simulink (R)) for five-and seven-level output voltages, and they strongly support the validity of the proposed inverter. These positive results are further supported experimentally using a laboratory prototype.