Finite control set model predictive control of a stacked multicell converter with reduced computational cost

Abstract

Multilevel converters are an attractive alternative for medium voltage applications. The Stacked Multicell Converter (SMC), in particular, is a multilevel converter that allows to increase the output voltage level compared with the classical Flying Capacitor Converter, while decreasing the stored energy in the converter. This paper presents the application of Model Predictive Control (MPC) in a three phase SMC with three cells and two stacks (3×2). The strategy controls simultaneously the load currents and capacitor voltages. A problem about the implementation of MPC is the computational cost, which is bigger for multilevel converters. In the case of SMC 3×2 it is necessary to do 19683 iterations, for This paper proposed a new method to implement MPC reducing the necessary iterations from 19683 to 343. Simulation results show that the proposed MPC strategy produces an effective control of the load current, while keeping balanced capacitor voltages and lower THD that classical MPC with 57.38 times lower iterations.