Super twisting sliding mode control of three-phase grid-tied neutral point clamped inverters

This paper presents an effective sliding mode control defined on the basis of super twisting algorithm (ST-SMC) for three-phase grid-tied three-level neutral point clamped (NPC) inverters. Unlike the existing SMC techniques devoted for grid-tied NPC inverters, the proposed ST-SMC method suppresses chattering and achieves good tracking performance while maintaining the prominent features of the sliding mode control such as robustness and simple implementation. Furthermore, the proposed ST-SMC method has the ability to operate with imbalanced and deteriorated grid voltages. The steady-state and transient performances of ST-SMC with ideal, imbalanced and deteriorated grid voltages are investigated experimentally. The experimental results expose that the presented control approach offers fast transient response and achieves the grid current control with small total harmonic distortion.