Fault-Tolerant Operation of a Multimode Stacked Switch Rectifier Leg Through Built-In Circuit Redundancy

In this article, the open-circuit fault-tolerant operation of a multimode stacked switch rectifier leg is presented and investigated. A fault-tolerant control technique is proposed through the built-in circuit redundancy operation of the presented multimode stacked switch rectifier leg. A bidirectional
CLLC
resonant dc–dc converter that employs the presented leg is used to demonstrate the features of the presented control scheme. The proposed control can allow post fault operation of the converter to continue to deliver the demanded load power with soft-switching operation in case any switch experiences an open-circuit fault. In addition, the built-in circuit redundancy of the leg allows the resonant converter to operate in different operating modes, resulting in an enhanced control in regulating the output voltage while avoiding the switching frequency to diverge far from the resonant frequency, leading to better performance and improved efficiency with the complete soft-switching operation before and after the fault. To highlight the merits of the proposed fault-tolerant control in the multimode stacked switch rectifier leg, experimental results are provided on a 300-W resonant converter prototype with an input of 250 V and an output voltage of 400 V.