Optimized-Pulse-Pattern Multistep Finite-Control-Set MPC With Real-Time Validation

This paper addresses the main performance issues of multistep–finite–control–set model predictive control (MFCS–MPC) that make it impractical in medium–voltage high–power grid–connected converters. Current MFCS–MPC techniques synthesize nonperiodic steady–state voltages that produce harmonic–rich continuous and unpredictable Fourier spectra with variable switching frequency. This article leverages advances in optimized pulse patterns and MFCS–MPC to meet grid codes while operating at a low, fixed switching frequency and rendering a fast dynamic response. To keep the strategy viable in real–time, enhancements to the sphere decoder algorithm that solves the optimization problem were made, and the computationally efficient Frank–Wolfe algorithm was used to find a new center for the sphere during transients. The control scheme is assessed through simulation and hardware–in–the–loop experiments, demonstrating its real–time viability.