ENHANCEMENT OF FUNDAMENTAL RMS OUTPUT VOLTAGE OF 5-LEVEL CASCADED H-BRIDGE MULTILEVEL INVERTER USING MODIFIED MULTI-CARRIER PWM TECHNIQUE

Cascaded H-bridge Multilevel Inverter (CHBMLI) is the most suitable topology for the PV power converters. In this paper an effort has been made to increase the performance of CHBMLI by improving the fundamental Root Mean Square (RMS) value of the output voltage. This work proposes a Modified Multi Carrier PWM (MMCPWM) technique where, reference sine wave has been replaced by ellipse wave, resulting in enhanced performances on the fundamental rms output voltage and lower Total Harmonic Distortion (THD). Analysis of single phase 5-level CHBMLI with and without load are carried for the different Multi Carrier PWM (MCPWM) techniques. Results were compared for both MCPWM and MMCPWM at different modulation indices. The proposed MMCPWM technique emerged as a very promising technique in enhancing the fundamental output voltage and at the same time mitigating the problem of THD. 5-level CHBMLI with the proposed control strategy is simulated in MATLAB/SIMULINK. The results were compared with the existing literature for validation of the proposed control strategy.