Open-Circuit Fault Detection and Tolerant Operation for a Parallel- Connected SAB dc-dc Converter

This paper presents an open-circuit fault detection method and its tolerant control strategy for a Parallel-Connected Single Active Bridge (PCSAB) dc-dc converter. The structural and operational characteristics of the PCSAB converter lead to several advantages especially for high power applications. By paralleling modular converters, the power and current ratings of each modular converter can be lowered and by interleaving the switching patterns, the input and output current ripples can be significantly reduced without increasing switching losses or device stresses. Apart from these, the PCSAB converter also possesses better reliability under a certain open-circuit fault condition. The proposed fault diagnosis method identifies both location and type of a fault using one current sensor in the output. Depending on the type of the fault, the proposed fault-tolerant strategy tries to keep the capability of the converter unaffected or to improve the quality of the output current under the fault condition. The feasibility of the proposed fault detection and fault-tolerant methods are verified by simulations and experiments.