Finite-Time Disturbance-Observer-Based Integral Terminal Sliding Mode Controller for Three-Phase Synchronous Rectifier

Bahman Eskandari,Jorma Kyyra,Moosa Ayati,Amin Yusefpour,Edris Pouresmaeil

doi:10.1109/access.2020.3017460

Abstract

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.

Highlights

There is a vast area of applications for synchronous threephase rectifier (SR) in the industrial world such as regenerative motor drives, industrial DC power supplies, common DC bus for multiple drives, and DC traction systems
A new control structure of three-phase synchronous rectifier was developed based on the integral terminal sliding mode controller
The proposed control technique was implemented on a non-linear and time-varying model of a three-phase grid-connected converter in the conventional synchronous reference frame

Summary

INTRODUCTION

There is a vast area of applications for synchronous threephase rectifier (SR) in the industrial world such as regenerative motor drives, industrial DC power supplies, common DC bus for multiple drives, and DC traction systems. A new approach for control of three-phase SR is proposed in [15], [16], which relies on an extended state observer (ESO)-based secondorder sliding mode (SOSM) In this method, two control loops for voltage regulation (outer loop) and instantaneous power tracking (inner loop) are considered. A conventional PI controller produces the desired active power and corresponding currents (in αβ frame) for tracking DC voltage, and two loops of Integral Terminal Sliding Mode controllers (ITSMC) are utilized to generate the desired voltage values in αβ coordinate. By considering the variation of DC load as an external disturbance in the non-linear state-space equation (12) and including unknown uncertainties, integral terminal sliding mode controller and disturbance-observer concepts are raised .

INTEGRAL TERMINAL SLIDING MODE CONTROL

VOLTAGE REGULATION LOOP

SIMULATION AND EXPERIMENTAL RESULTS

Findings

CONCLUSION