An Improved Phase-Shifted Full-Bridge Topology with High Fault Tolerance

Phase-shifted full-bridge (PSFB) converters are widely used in vehicular power supplies due to their simple structure, wide output voltage range, and high power density. Their high reliability is crucial for driving safety. However, complex operating conditions impose significant stress on power devices. Once a power device fails, the converter ceases to function.To endow the converter with fault tolerance, this paper proposes a novel fault-tolerant strategy aimed at enabling the PSFB converter to maintain rated voltage output during a single power device open-circuit fault. This strategy adds an abnormal judgment on the primary-side overcurrent protection function to reduce the occupation of system time resources. After performing a specific switching sequence, the open-circuit mosfet can be quickly located, and the converter can be switched to the asymmetric half-bridge (AHB) operation mode after a fault, keeping the output voltage constant. This paper provides a detailed analysis of the operating principles of PSFB and AHB converters, the fault detection mechanism, and the mode-switching logic. The effectiveness of the proposed strategy is validated through theoretical analysis, simulation, and hardware experiments. Experimental results demonstrate that this strategy significantly enhances system reliability and fault tolerance.