A Novel Extended Sliding-Mode Predictive Control With Dynamic Optimization and Virtual Voltage Vectors

This article proposes a novel extended sliding-mode predictive control strategy for three-phase three-level voltage source inverters. Initially, the control domain is established using sliding-mode theory, dynamically reducing the search space. Subsequently, a unique parallel optimization strategy is presented in the two-phase stationary coordinate system, with an analysis of the monotonicity of the cost functions and the constraints within the search space. Compared to traditional model predictive control, this approach results in a calculation time reduction of at least 51.3%. To mitigate output ripple, a novel design method for virtual voltage vectors (VVVs) is proposed based on α and β components, demonstrating notable scalability. At the same time, to maintain neutral point voltage balance, two output modes are devised for the VVVs using redundant small voltage vectors, eliminating weighting factors. Additionally, the excessive voltage jumps are mitigated and the method operates at a constant switching frequency. Experimental results robustly validate the algorithm's superior performance.

I. Introduction

Three-phase three-level voltage source inverters (3P-3L VSIs) with LC-filter represent a prevailing topology in applications such as ac microgrids, distributed generation systems, and uninterruptible power supplies [1], [2], [3].