Comparative analysis of THD for symmetrical and asymmetrical 17 level cascaded H-bridge inverter using carrier based PWM techniques

In this paper various multicarrier PWM schemes are simulated, to reduce the THD and enhance the output voltage waveforms for 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 cascaded H-bridge 17-level inverter. Simulation for 17- level cascaded H-bridge inverter (CMLI) has been carried out in MATLAB/ Simulink and simulation results for voltage waveform and harmonic spectrum are presented in this paper and analyzed.