Novel cascaded H-bridge multilevel inverter with harmonics elimination

Multilevel inverter is one of the most recent and popular type of advances in power electronics. It synthesizes desired output voltage waveform from several dc sources used as input for the multilevel inverter. This paper presents the two techniques for improving the quality of the output voltage and efficiency. First, new novel topology for multilevel inverter is introduced which reduces the number of switches compared to other for the same level of output voltage. Second, Selective Harmonics Elimination Stepped Waveform (SHESW) method is implemented to eliminate the lower order harmonics. Fundamental switching scheme is used to control the power electronics switches in the inverter. The proposed topology is suitable for any number of levels. When the levels are increased the number of switches used is reduced compared to the conventional cascaded H-bridge multilevel inverter. This paper is particularly focuses on seven level inverter. In the proposed topology only 7 switches were used. The harmonic reduction is achieved by selecting appropriate switching angles. It shows hope to reduce initial cost and complexity hence it is apt for industrial applications. In this paper third and fifth level harmonics have been eliminated. Simulation work is done using the MATLAB software which validates the proposed method and finally THD comparison is presented for analysis.