Adaptive grid current feedback active damping for active front end converters

Abstract

Grid current feedback based Active Damping (AD) method is a preferable option in Active Front End (AFE) converter due to the need for less number of sensors and cost efficiency. However, AD performance is dependent on the model knowledge about LCL filter parameters and resonant frequency. In practical system, grid impedance is possibly not known, thus, in combination with LCL filter, resonant frequency is changed while stability margins and performance reduced. To address this problem, this paper proposes extremum seeking based adaptive active damping control method that is adaptive to different grid impedances, consequentially improving damping performance and stability of the active front end converter. The proposed method is verified through extensive simulations.