A seven level multilevel inverter topology with improved results using PWM technique

The new emerging multilevel inverter topologies with reduced device count, better control strategies, improved modulation schemes and capability to address various operational issues have proved to be highly superior to that of two level inverters and the conventional multilevel inverter topologies. This paper presents significantly improved results of an existing 6 switches and 4 DC sources multilevel inverter topology to produce great perfection in the seven level output voltage waveform. The major impact of the improved results is the reduction in total harmonic distortion (THD). The control methodology employed is Level Shifted PWM technique, based on which the topology is simulated for Phase Opposition Disposition, Alternate Phase Opposition Disposition and Alternate Phase Opposition Disposition + Variable Frequency modulation techniques. Multilevel Inverters today present a viable solution for high dynamic performance and power quality seeking applications, ultimately focusing to achieve almost perfect sinusoidal output voltage with minimum harmonic content. Thus, in this paper an effort is made to reduce the THD in the output voltage waveform. An analysis is done and a comparison is also made between the existing results and the new results obtained. These results are verified using MATLAB/SIMULINK and the analysis of harmonic spectrum is done through the Fast Fourier transform window.