A Robustness-Enhanced Dual-Loop Control Strategy Based on SMC for Vienna Rectifier

Although the Vienna rectifier is a promising rectifier topology for broad applications, its high-performance control is susceptible to disturbances such as parameter mismatches and load variations. To enhance the robustness against disturbances while maintaining a low chattering level, this article proposes a novel observer-based terminal sliding mode controller (TSMC) approach for current-loop control. First, after analyzing the inherent chattering and inaccurate voltage vector selection associated with conventional TSMC, we develop an error-based fixed-time supertwisting extended state observer (FTST-EESO) and integrated within the TSMC framework. This integration effectively improves the dynamic response, suppresses chattering, eliminates zero-crossing current distortion, and ensures balanced neutral-point voltage. Second, recognizing the limited robustness of conventional proportional-integral (PI) controller in voltage-loop control, we propose a hybrid control strategy termed the barrier function-based adaptive-gain supertwisting algorithm (BAGSTA). By constructing adaptive control gains based on positive-definite barrier function (PBF) and synthesizing the merits of PI controller and the supertwisting algorithm (STA), BAGSTA enables the system to flexibly configure the controller under diverse operating conditions, exhibiting high performance and enhanced the robustness in both steady-state and transient operations. Finally, the effectiveness of the proposed scheme is validated through experimental results.