Parameter-free ultralocal model-based predictive voltage control for three-phase four-leg inverters

The presence of fluctuating, unbalanced, and nonlinear loads poses challenges for the traditional predictive control of four-leg inverters. A novel ultralocal model (ULM) method based on extremum seeking control (ESC) for four-leg voltage source inverters is presented in this paper to address these problems. The ULM control gains are optimized online based on ESC, minimizing the prediction error, and effectively eliminating the dependence of the control effect on physical parameters and the influence of system uncertainties on the ULM control effect. All proposed methods were verified by extensive hardware-in-the-loop (HIL) experiments under different load conditions, and in comparison to the conventional model predictive control (MPC) and model-free control, proving that the proposed methods can significantly enhance anti-interference capabilities, control robustness, and power quality.