Finite Control Set Model Predictive Control of an Active Nested Neutral-Point-Clamped Converter

Abstract

The flying capacitors (FCs) of the nested neutral-point-clamped (NNPC) converter show an inherent voltage ripple at the fundamental frequency. This ripple can be significantly large under some operating conditions of the converter and hence can affect the performance. In this paper, a modified NNPC is proposed, so called active NNPC (ANNPC) converter. Like other multilevel converters, ANNPC also required capacitor voltage balancing, therefore finite control set model predictive control (FCS-MPC) scheme is proposed to control such objective. A mathematical model is developed to be used in the FCS-MPC. The performance of the ANNPC is compared with the NNPC in terms of capacitor voltage ripples and the total harmonics distortion of the output voltage and current. The results are validated by simulations.