An Improved Stacked Multicell Converter with Fault Tolerant Capability Using Finite-Control-Set Model Predictive Control

The stacked multicell (SMC) converter suffers from low-frequency voltage fluctuations in the neutral point (NP), which gets substantially larger at specific operating conditions and affects the safe operation of the converter. This paper proposes an improved SMC (ISMC) converter to cope with this shortcoming. A finite control set model predictive control (FCS-MPC) strategy is designed to accurately track the output current and voltage balancing across the flying capacitors (FC). With this strategy, a fault-tolerant ability of the proposed converter is also presented. A post-fault reconfiguration of the controller is proposed to achieve FC voltage balancing under bidirectional switch faults. Simulation results under steady-state, dynamic, and faulty operating conditions justify the feasibility of the proposed converter.