A carrier redistribution PWM for dual inverter with separated DC circuits

This paper deals with a proposal of a carrier redistribution PWM and its comparison with a phase disposition PWM (PDPWM) and carrier redistribution PWM for a multilevel converter dedicated to high power medium voltage electric drives. The converter topology is based on a cascaded connection of two-level inverters, the so called dual inverter. The well known phase disposition PWM for multilevel converters is modified for the above mentioned topology and its derivation as carrier redistribution PWM (CRPWM) strategy is employed. The proposed CRPWM enables the reduction of unbalanced load of the power electronics switches and increasing in the maximum output power rate. The functionality of the proposed PWM strategy has been verified on a simulation model of the converter as well as by experiments. The proposed PWM strategy has been compared with the standard PDPWM according to selected criteria such as total power losses, balanced load of switching devices and THD of phase load voltage waveforms.