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

Fault-tolerant methods have been recognized for improving the reliability of multi-phase bidirectional DC-DC converters. Few fault-tolerant 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 paper, the behaviors of the CF-DAB converter are comprehensively analyzed when an open-circuit fault occurs in different fault scenarios. Analysis and proposed fault-tolerant method are aimed to determine the open-circuit cases which can recover full conversion power after the fault occurs. Moreover, this paper 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 multi-phase current-fed converters. A 6-kW prototype is built to verify the proposed method.