The LLC (Inductance Inductance capacitance) resonant converter offers advantages such as high power density, high efficiency, and compact size, making it widely used in photovoltaic power generation systems. Its operational reliability is crucial for the continuous performance of these systems. However, complex operating conditions and variable climates can adversely affect power equipment. Switch fault diagnosis and remedial measures are essential aspects of designing isolated full-bridge DC-DC converters, significantly enhancing overall system reliability. When a switching component fails, the resonant converter cannot operate near its resonant point, leading to substantial reductions in efficiency and output power. To improve system fault tolerance and reduce maintenance costs, this paper proposes an improved LLC topology and a rapid switch short-circuit fault diagnosis method for phase-shift full-bridge converters. By real-time monitoring of the average voltage of the resonant capacitor, the method quickly identifies switch short-circuit faults within a single switching cycle, enabling topological control of faulty and redundant components. The modified topology ensures stable output voltage and power while allowing the converter to operate near the resonant frequency. The paper discusses the working principle, design considerations, and implementation of this approach. Simulation results verify the effectiveness of the proposed method.
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