Grid-Connected Three-Phase H-Bridge Inverter with Level Doubling Network Controlled by Staircase Modulation Techniques

This paper presents a grid-tie three-phase five-level H-bridge (HB) inverter with Level Doubling Network (LDN), controlled by different types of staircase modulation technique. This structure allows, with reduced number of active switches and isolated DC sources, generating the same number of inverter voltage levels (five), in comparison to a standard cascaded H-bridge (CHB) topology with two HB cells in one phase, while still maintaining the same power quality. Furthermore, the implementation and comparison of different staircase modulation techniques gives an overview of their pros and cons with respect to total voltage harmonic distortion (THD), complete spectral harmonic attenuation, and elimination of a particular harmonic in a wide modulation index range.