标题：A Repetitive Control Scheme for Circulating Current Suppression in Parallel Three-Level T-Type Inverters Under Unbalanced Conditions
作者：Qin, Changwei; Chen, Alian; Xing, Xiangyang; Du, Chunshui; Zhang, Guangxian; Zhang, Chenghui; Ding, Wenlong
作者机构：[Qin, Changwei; Chen, Alian; Xing, Xiangyang; Du, Chunshui; Zhang, Guangxian; Zhang, Chenghui; Ding, Wenlong] Shandong Univ, Sch Control Sci & Engn, J 更多
会议名称：2017 9th Annual IEEE Energy Conversion Congress & Exposition (ECCE)
会议日期：OCT 01-05, 2017
来源：2017 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)
关键词：Circulating current suppression; repetitive control; parallel 3LT(2)Is;; unbalanced conditions
摘要：Parallel three-level T-type inverters (3LT(2)Is) can increase power rating and reliability, but the circulating current problem will arise. Unbalanced conditions including unbalanced filter inductances and unbalanced grid voltage have negative effects on the operation of parallel 3LT(2)Is. This paper presents an improved repetitive control scheme for circulating current suppression in parallel 3LT(2)Is under unbalanced conditions. An average model of parallel 3LT(2)Is in dq0 reference frame is derived to analyze the circulating current. It can be seen that unbalanced filter parameters generate additional disturbance in zero-axis current system. A repetitive controller is designed to mitigate the disturbance caused by unbalanced filter parameters, and feed-forward terms are introduced to eliminate the remaining disturbances. The proposed control scheme can effectively suppress the circulating current in parallel 3LT(2)Is under unbalanced conditions. Experimental results are presented to demonstrate the effectiveness of the proposed scheme.