Control of a 3 level T-type PWM solar inverter

Abstract

The three-level T-type inverter (3LT2I) is a commonly used multilevel inverter topology that displays a significant similarity to the Neutral Point Clamped (NPC) topology. In this dissertation, basic working principles and commutation process of the 3LT2I are studied in a comprehensive way including comparing with conventional two-level inverters and other multilevel topologies. Both open loop and closed loop model are built with MATLAB/Simulink. A LC filter is designed to reduce the output current ripple to less than 10% and a closed loop controller is designed to enable the inverter system to have a voltage stability when the load increases and decreases. Additionally, switching losses and conduction losses in 3LT2I are evaluated and compared to the NPC inverter with simulation methods.