A hybrid multilevel inverter employing series-parallel switched-capacitor unit

This paper presents a new hybrid multilevel inverter (MLI) which adopts switched-capacitor (SC) to step-up the voltage and improve the output power quality. With a simple series-parallel unit, the voltage magnitude and number of output levels of the inverter are doubled. The proposed topology can be applied to arbitrary number of series-connected voltage sources. This paper also suggests the design of gate drive voltage supplies and a scheme to substantially reduce the number of active components for high power factor applications which further simplifies the design and system cost. Due to the considerable increase in number of output levels, the proposed SCMLI has satisfactory output power quality with simple staircase modulation techniques switching at fundamental frequency. The working principle of the proposed SCMLI and the associated staircase modulation technique presented here are studied and verified by simulation and experiment.