Predictive control algorithm robustness for achieving fault tolerance in multicell converters

Multilevel Converters (MCs) have emerged as a promising alternative to traditional two level converters. MCs use an arrangement of several semiconductors to synthesize high quality output voltage levels. Unfortunately, as a consequence of using more switching elements, MCs are, in general, more likely to be affected by faults, than their two level counterparts. In this paper, we propose a finite set constrained predictive control method for MCs, which is aimed at achieving robustness to failures in the semiconductors. We focus on three-phase multicell flying capacitor converters and show that, by carefully designing switching sequences, faults can be isolated from measurements provided by a single voltage sensor per phase. When faults occur, the proposed controller reconfigures the converter to provide to the load voltages which are similar to those obtained under normal, i.e., fault free, operating conditions.