As the power demand is increasing continuously, the use of non-conventional energy sources is increasing rapidly. Among the different non conventional energy sources, solar energy is finding more application. The solar energy is converted in to electricity which is DC in nature by using the PV modules. In order to convert from DC to AC Multilevel inverters are used. As the voltage level increases the THD decreases in MLI. In this paper an asymmetrical multilevel inverter which has four main switches and one H-bridge has been implemented. With this circuit we are generating 21 level of output voltage with reduced THD which can be used for standalone PV application. This topology uses less number of power switches and diodes as compared to other conventional MLI. For controlling the output voltage of this topology multi-carrier different PWM techniques are used. And the results of different PWM techniques are compared for different modulation index and FFT analysis is done by using the MATLAB SIMULINK software.

Keywords : Multi-level inverter (MLI), pulse width modulation (PWM), Total harmonic distortion (THD), Phase disposition (PD), Phase opposition disposition (POD), Variable frequency (VF).