Multiobjective Model-Free Predictive Control for Motor Drives and Grid-Connected Applications: Operating With Unbalanced Multilevel Cascaded H-Bridge Inverters

Abstract

A multiobjective model-free predictive control (MO-MFPC) strategy is proposed in this article for multilevel cascaded H-bridge (MLCHB) inverters with unbalanced conditions. The compensated current variation (CCV), which allows the inclusion of the proportional and integral terms into the cost function, is generalized to improve the accuracy of MFPC over a wide range of applications. The new extended CCV is used to define the voltage control objective without involving the output voltage model of MLCHB. This voltage control objective is used to evaluate all state candidates to achieve a suitable subset for the current control objective. To achieve a better tradeoff between the current accuracy and the injected common-mode voltage (CMV), CMV is added to the cost function. Simulations and experimental evaluations show that, compared to existing MFPCs and classic model predictive control for MLCHB inverters, MO-MFPC achieves a better current accuracy over a wide range of applications and unbalanced MLCHB operating conditions.