Nonlinear–MPC–Based Cluster Energy Control of Modular Multilevel Matrix Converters

This paper presents an optimal reference generator of the common-mode voltage and circulating currents based on a long-horizon model predictive control approach to jointly perform the inter-cluster capacitor voltage balancing and the low-frequency oscillation mitigation to achieve cluster energy control in Modular Multilevel Matrix Converters (M3C) over the whole range operating frequency. The Block Coordinate Descent method is applied to the nonlinear quadratic problem to determine both variables in realtime simultaneously.