Finite-Time Disturbance-Observer-Based Integral Terminal Sliding Mode Controller for three-phase Synchronous Rectifier

This article is concerned with the design of a finite-time disturbance-observer-based integral terminal sliding mode controller for the effective performance of three-phase synchronous rectifiers. The proposed control technique is developed based on the conventional synchronous reference frame model of the three-phase grid-connected converter, and the system dynamics is described in terms of a time-varying non-linear state equation. The variation of DC-load is considered as a disturbance. Therefore, a combination of a fast disturbance observer and an integral terminal sliding mode controller is utilized to produce the reference value of the direct axis for the current control loop. In this research, by employing Lyapunov stability theorem in the theoretical analysis and by numerical simulations, it is confirmed that the proposed closed-loop system is stable and the states converge to desired values in finite time even in the presence of load disturbance and control input saturation. The integral terminal sliding mode controller is utilized to maintain a robust performance along with a faster response of the converter. In order to demonstrate the performance ability of the proposed control scheme under real condition, an AC power source, impregnated with low order harmonics, is assumed. A real-time laboratory setup of the synchronous rectifier has been developed successfully, and the effective performance of the proposed control technique is fully proven.