Super twisting sliding mode control for inner current suppression of Modular Multilevel Converter

Abstract

Modular Multilevel Converter (MMC) is very popular due to its flexibility, use of low rating devices, low harmonic distortion, and high efficiency. Despite these advantages, MMC faces challenges of controlling its parameters especially inner current and capacitor voltages. This paper presents the control of the inner current of MMC using Sliding Mode Controller (SMC). The switching function of SMC is based on 2nd order super twisting algorithm. The Proposed super twisting algorithm is proved to be efficient in controlling the inner current. The 2nd order harmonic is effectively suppressed, and the inner current is fully converged to its reference value. Moreover, the continuous nature of the super twisting algorithm solves the chattering issue. The implementation of MMC and its control is carried out in MATLAB/Simulink.