Extensive study over Z-source inverter (ZSI) has been pursued for years to compensate the drawbacks of the conventional converters. Single stage (one-step) conversion with buck-boost characteristics was the primary features for its wide usage. But presence of passive elements may prove to be a disadvantage as the size of the converter increases along with its ratings. Modifications on such converters leading to different topologies have been discussed briefly in this paper. The comparative study based on reduced passive elements and better gain is done to obtain an optimal converter structure.