A Feedforward-Prevailing Control Method to Improve Dynamic Responses for Paralleled Inverters With Small Interfacing Inductors

This article presents a current control method to increase the control bandwidth for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i>-paralleled inverters with small interfacing inductors driving a surface-mounted permanent magnet synchronous motor. In a distributed control scheme, where the state information of each inverter is not shared with the other inverters, the controllers derived from the conventional methods may struggle to achieve high control bandwidth due to unstable responses caused by circulating currents. This article explains how circulating currents limit the control bandwidth through the analysis based on the closed-loop transfer function for the paralleled inverters. In the proposed method, a filtered current reference is utilized to modify the classic control structure so that the feedforward response prevails. In order to demonstrate the effectiveness of the proposed method, hardware-in-the-loop test results are presented and discussed in detail. The proposed method facilitates fast dynamic responses, while asymptotically stable responses for circulating currents are ensured.