Comparative Analysis of Phase Disposed Carrier Wave Modulation for Asymmetric Three Phase Multilevel Inverter

The multilevel inverter is a power electronic circuit that can give output voltage with multiple levels and be worked in inverter or rectifier mode. It is a highly efficient technique for DC to AC power conversion in solar photovoltaic systems due to its low total harmonic distortion (THD), low switching loss, low electromagnetic distortion for medium voltage and high-power applications. This paper describes a newly effective topology which has only eighteen switches, six voltage sources and six power diodes for three phase seven level inverter. For the controlling process of multilevel inverter different phase disposed carrier wave modulations are used. The aim is to thoroughly investigate and evaluate some optimum conditional points for these control techniques based on which proposed inverter will be more feasible and efficient. The effectiveness of the proposed system has been verified through simulation analysis in the MATLAB/Simulink software environment. From the simulation, it is observed that the proposed topology reduces the number of switches, voltage sources and power diodes among existing topologies. Based on the simulation result, it is also observed that the optimum modulation index and carrier frequency for PODSPWM are 1.10 and 1000Hz and for PODTRPWM are 1.10 and 1000Hz and for PODSDPWM are 1.0 and 1000Hz and also for PODTHPWM is 1.0 and 1000Hz and PODTRPWM offers better result in terms of THDs and PODSDPWM offers less switching losses among different topologies. The proposed asymmetric multilevel inverter offers less amount of switching devices. Besides, the efficiency of the inverter is increased due to minimum switching loss as well as reduced overall system installation cost.