Dc-link voltage drift compensation in a four level Double-Star Converter using redundant states via phase-shifted PWM strategy

The following work introduces the use of the available Redundant switching states introduced by the double star four level converter topology, for its application in a medium voltage variable speed drive under a wide range of operation loads. Redundant switching states are obtained using multi-carrier phase-shifted pulse width modulation (PWM) strategy. The converter performance is evaluated in terms of the dc-voltage drift and the torque ripple on the load side, when compared with a classical level-shifted PWM modulation.