Comparison of using carrier-based pulse width modulation techniques for cascaded H-bridge inverters application in the PV energy systems

Four types of carrier-based pulse width modulation (CBPWM) techniques used to control a two-cell single-phase cascaded H-bridge (CHB) inverter with separated dc power sources, are compared the simulation results in this paper, in order to find out the most suitable CBPWM technique for CHB grid-connected inverter focusing on the effect of total harmonic distortion (THD) of output current and voltage, size of filter, and implementing simplicity. These functions are derived from a conventional unipolar modulation method with triangular carrier wave for each H-bridge cell. Each modulation technique was developed to provide a five voltage-levels output waveform with a non-unity power factor load. The simulation results have been verified of using all CBPWM techniques to control a two-cell single-phase CHB inverter with the same conditions.