Comparative Evaluation of Multilevel Modular Inverter Topologies

摘要

Modular multilevel inverters are best suited for high voltage high power applications since it offers low switching frequency and low THD. Hence they are made use in HVDC, electric railway supplies, high power motor drives etc. Modular multilevel inverter is composed of discrete modules. It can have any number of modules corresponding to the number of voltage levels required. Hence the number of levels can be increased without increasing the complexity of the circuit. The quality of output voltage increases with increase in number of levels thereby eliminating the need for output filters with increased number of levels. Three level, five level and seven level modular inverters are simulated and their parameters are compared. The principle of operation and carrier based pulse width modulation for seven level modular inverter is discussed. The modulation technique presented is confirmed by simulation conducted in MATLAB/SIMULINK