Versatile Current Controller Employed In Three-Level Active Front-End Converter Based Power Supply For Unity Power Factor and Low Harmonic Distortion In Grid Current

Abstract

This paper presents analysis of a three-level front-end boost-converter with current error space phasor based hysteresis controller applied to it. Analysis of operating range of three-level converter, including overmodulation region is presented in this paper. The controller is self-adaptive in nature, and takes converter from three-level to two-level mode of operation following various trajectories of sector change with the change in reference dc-link voltage demanded by load, keeping current error space phasor within the prescribed hexagonal boundary. The proposed controller ensures switching of only adjacent voltage vectors for position of reference voltage vector in a given sector of voltage space phasor structure of front-end converter (FEC). Unity power factor and low total harmonic distortion (THD) in grid current under various steady state conditions are quite evident from the presented results for the proposed controller based FEC.