Model-Free Predictive Current Control for Multilevel Voltage Source Inverters

Abstract

This article proposes a generalization of the model-free predictive current controller (MFPCC) for multilevel voltage source inverters (VSIs). MFPCC is an alternative to mitigate the parameter sensitivity faced by model-based PCC (MPCC), but it requires a constant update of the stored current variations (CVs) associated with each VSI state to provide a prediction, which results in a satisfactory closed-loop response. When a multilevel VSI is considered the number of states increases, which results in a decrease of the CV update rate, since only one state can be updated at each sample. To solve this issue, the extended adjacent state scheme is used to reduce the possible number of solution candidates and then a controlled CV is used to compensate the updated CV. Simulation and experimental results obtained with a sampling rate of 5 kHz show that the proposed MFPCC exhibits performance similar to the one of MPCC for nominal parameters. However, a better current response is obtained in the case of the load parameter mismatch, especially at steady state.