Open-Circuit Fault-Tolerant Method for Three-Phase CF-DAB Converter with Auto-Balancing Control

Fault-tolerant (FT) methods have been recognized for improving the reliability of multiphase bidirectional dc-dc converters. Few FT methods for current-fed dual-active-bridge (CF-DAB) converter have been developed, because it becomes more challenging due to the asymmetrical structure between primary and secondary sides. In this article, the behaviors of the CF-DAB converter are comprehensively analyzed when an open-circuit fault (OCF) occurs in different fault scenarios. An analysis and the proposed FT method are aimed to determine the open-circuit cases, which can recover full conversion power after the fault occurs. Moreover, this article also proposed an auto-balancing control method to prevent the converter from being out of control. The proposed balancing control method can be utilized for general multiphase current-fed converters. A 6-kW prototype is built to verify the proposed method.