This paper focusing onthe comparison of total harmonics distortion (THD) of the output voltage is minimized by the help of a cascade multilevel inverter with reduced number of switches with un-equal DC sources using the conventional PWM techniques and modified SHE PWM using particle swarm optimization (PSO) algorithm. To address the issues of the multilevel inverters with better performance and efficiency there has been increased advancements with level shift PWM technique, phase shift PWM, POD PWM, APOD PWM and NLC PWM. The paper deals with the analysis of some such advancements like particle swarm optimization techniques and is contrasted to pulse width modulation technique in terms of total harmonic reduction, feasibility, switching pattern of PWM techniques and efficiency. Due to the conventional PWM techniques the complexity of the increased number of elements and harmonics can be reduced with the particle swarm optimization technique and can also determine the optimized switching angles in reducing the selected harmonics. The simulations of the analysis are carried out in the Matlab and the same are presented in the paper which are indeed proved to be better for PSO in contrast to conventional PWM techniques.