Single-Phase Cascaded H-Bridge Inverters Without Power Regeneration

Cascaded H-Bridge (CHB) inverters may have some of its cells with a bidirectional power flow between the source and the load for some dc-link voltage ratios and modulation indexes, regardless of the load power factor. Considering this, in this paper switching strategies for single-phase multilevel CHB inverters are presented for applications in which the regenerative mode is not desired, forcing all the cells to have either null or positive power flow towards the load. In order to validate the proposed techniques, a study with single-phase CHB invertes composed of two and three cells is made. The converters equations and level shifted pulse width modulation (LSPWM) technique are given. The topologies are compared with different dc-link ratios in terms of operation range and power distribution. Simulation and experimental results are provided to validate the performance of the systems.