Passivity-Based Nonsingular Terminal Sliding-Mode Control for LC-Filtered Current Source Converter

It is a big challenge for current source converter (CSC) to ensure the desired tracking performance, robustness, and immunity simultaneously in the presence of resonance caused by the grid-side LC filter and slowly time-varying filter parameters or load disturbances. Aiming at this problem, combining the advantages of passivity-based control (PBC) and nonsingular terminal sliding mode control (NTSMC), a hybrid PBC-NTSMC method is proposed. Based on virtual damping injection and energy dissipation theory, the PBC is first designed for the inner loop followed by the construction of the Euler-Lagrange model. In this way, the resonance suppression is realized and the CSC system is proved to be passive. Furthermore, the NTSMC is combined with PBC to improve the dynamic response, reduce the chattering problem of traditional sliding mode control, and enhance the robustness of the system while maintaining passivity. In addition, the power references are modified to enable system to flexibly configure the control target depending on actual application requirements under nonideal grid. To further enhance the immunity, an ultralocal model predictive controller based on extended state observer disturbance estimation is designed for the outer loop. Finally, the simulation and experimental results verify the effectiveness of the proposed method.