Zero-steady-state-error input-current controller for regenerative multilevel converters based on single-phase cells

Multicell converters are one of the alternative topologies for medium-voltage industrial drives. For an application requiring regenerative capability, each power cell must be constructed with a three- or single-phase pulsewidth-modulation (PWM) rectifier as front end. The choice of single-phase PWM rectifiers for the input of the cells results in a reduced number of power switches and a simpler input transformer than the three-phase equivalent. However, its control is not as straightforward. This paper proposes the use of higher order resonant controllers in the classical control structure of the single-phase PWM rectifier. This ensures zero steady-state tracking error of the reference current at fundamental frequency. A detailed description of the design criteria for the position of the zeros and poles of the controller is given. Experimental results showing the good performance of the single-phase input cells and its proposed control are included.