Model predictive control of nine-level active nested neutral-point piloted converter

Abstract

In this paper, a finite control set model predictive control (FCS-MPC) is developed and applied to the hybrid Nine-level Active Nested Neutral-Point Piloted (9L-ANNPP) voltage source converter. A mathematical model for the converter is derived and then incorporated in the FCS-MPC. The objective of the control algorithm is to operate the converter at the desired reference output current while balancing the dc-link and flying capacitors' voltages. The balancing of the capacitors is achieved by utilizing the redundant switching states of the converter. The control algorithm is also applied to a similar hybrid 9-level converter to compare the output quality of both topologies. The effectiveness of the implemented FCS-MPC is evaluated by computer simulation under different operating conditions. The control algorithm is able to produce high quality output while maintaining the capacitors at the target voltage levels. The comparison of the two topologies shows that the 9L-ANNPP can produce similar output waveform quality despite of its reduced component count.