MODELLING AND EXPERIMENTATION OF MODIFIED CASCADED MULTILEVEL INVERTER WITH OPTIMIZED OUTPUT

Abstract

Multilevel inverters are becoming more popular in the electrical sector owing to its high output voltage capability. This high output voltage depends upon the no. of levels used in the multilevel inverter which in turn points towards the no. of switches associated with the levels. As long as the levels are increased by virtue of increase in switches, the output voltage waveform tends to be purely sinusoidal. But as the level increases the switching pattern becomes more and more complex. This paper focuses on optimization of AC voltage output from a 15 level Cascaded Multilevel Inverter (CMLI). The proposed CMLI has been remodeled with only one Dc source, 2 capacitors and 4 switches for each bridge with an intention to obtain 15 level output with minimum power consumption and reduced switching losses. As minimum no. of switches are incorporated in the proposed system, the switching pattern can be framed flexible and facile, which can be further extended to n levels with better THD. The switches for the proposed CMLI are controlled through an organized pattern resulting in a near sinusoidal output with a maximum of 15 levels. The proposed system was simulated using MATLAB simulation software. The hardware fabrication of the simulated structure with the corresponding test results are discussed in this paper.