Carrier-based hysteresis controlled constant switching frequency strategy for three-level inverter based DSTATCOM

This paper proposes the constant switching frequency current control technique using carrier-based hysteresis modulation, for three-level inverter based Distribution Static Compensator (DSTATCOM). The proposed scheme ensures constant and reduced switching frequency operation of three-level voltage source inverter (VSI). The analytical expressions are developed to select the proper carrier frequency range during positive, negative and zero-voltage states and design criteria is derived to avoid multiple and below crossings in the inverter switching dynamics. The proposed scheme is compared with the conventional three-level hysteresis current control and its improved performance in terms of bandwidth, Total Harmonic Distortion (THD) and switching frequency is presented. Furthermore, the proposed strategy is applied for DSTATCOM applications to achieve load compensation at constant switching frequency. The detailed simulation Using MATLAB environment and experimental studies are presented to explore the suggested scheme.