A General Fault-Tolerant Operation Strategy Under Switch Fault for Modular Series-Parallel DC-DC Converter

Modular series-parallel dc-dc converters (MSPDDCs) are good options in high-power high-voltage applications. A reliable operation should be a top concern in such critical situations. In this article, a general fault-tolerant method for switch fault is proposed for MSPDDC, including fast fault diagnosis (FD) and postfault reconfiguration. The FD is achieved using the relationship between output inductor voltage and gate driver signal in each module. The inductor voltage is acquired by adding a small auxiliary winding into the magnetic core, and no expensive sensors are introduced. A general and low-cost hardware circuit is designed to locate faulty module in a very short time. The reconfiguration process for four structures is then systematically presented. Through a careful timing sequence design, a fast and smooth hot swap is realized, and its impact on the output side and the other healthy modules is minimized. The principle of FD and reconfiguration, hardware implementation, and experimental verification are given in this article.