International Research Journal of Education and Technology

In this paper various multicarrier PWM schemes are proposed, which can reduce the THD and enhance the output voltages waveform from seventeen level inverter. Here, three modulation techniques are compared; constant switching frequency(CSF), Phase shift(PS PWM) and variable switching frequency (VSF). These schemes are applied for analysis of both symmetrical and asymmetrical structure of 17-level cascaded H-bridge multilevel inverter (CHB MLI). Simulation for 17- level CHB MLI has been carried out in MATLAB/ Simulink and simulation results for voltage waveform and harmonic spectrum are presented in this paper and compared.

Keywords-- Cascaded MLI; Symmetrical MLI; Asymmetrical MLI;Constant Switching Frequency; Phase Shift PWM and Variable Switching Frequency PWM ;Total Harmonic Distortion