Disturbance Observer-Based Finite-Time Control for Three-Phase AC-DC Converter

For three-phase ac-dc converters, load disturbances, and parameter uncertainties cause large fluctuations of the dc-link voltage, even resulting in system instability. In order to cope with this problem, the disturbance observer-based finite-time control (DOFTC) is put forward in this article, where the finite-time disturbance observer is designed to fast and accurately estimate disturbances. Subsequently, the stability of the ac-dc converter closed-loop system is analyzed and theoretically proved. Finally, experimental results verify the effectiveness of the DOFTC strategy, where good dynamic and steady-state performance is achieved under load disturbance and parameter uncertainties. Compared with the enhanced state observer-based sliding mode control and adaptive control method, the proposed DOFTC method not only reduced the fluctuations of the dc-link voltage by at least 55% but also improved the transient response.

Automated summary

In this article, disturbance observer-based finite-time control (DOFTC) is proposed to address the issue of large fluctuations of the dc-link voltage and system instability in three-phase ac-dc converters. A finite-time disturbance observer is designed to estimate disturbances accurately and quickly. The stability of the ac-dc converter closed-loop system is analyzed and theoretically proven. Experimental results validate the effectiveness of the DOFTC strategy, achieving good dynamic and steady-state performance under load disturbance and parameter uncertainties.