Finite-Time Control Strategy Based on Integral Terminal Sliding Mode for Three-Level Neutral Point Clamped Converter

To improve the capability of current loop of the three-level neutral point clamped (3L-NPC) inverter, the integral terminal sliding mode control (ITSMC) for the current inner loop of the 3L-NPC inverter is proposed. Firstly, the math equation of the system is set up. Secondly, the sliding surface of ITSMC is designed. Due to the introduction of proposed strategy, this method can ensure that the error of converter current converges to 0 in a fixed time. Thirdly, the controller of ITSMC is designed based on Lyapunov function. Besides, the stability proof of the strategy is derived as well. In comparison with the traditional proportional-integral (PI) method, the convergence velocity of the converter current is greatly raised, and the anti-interference ability of 3L-NPC is also enhanced. Comparative simulations between PI controller and proposed ITSMC method are put forward to verify the effectiveness and merits of ITSMC strategy.