To enhance efficiency within the wide voltage input range and comprehensive protection of onboard DC power supply, a modular design was implemented based on a full-bridge DC/DC converter. Initially, the working principle of the full-bridge DC/DC converter was thoroughly analyzed. Subsequently, the magnetic components were designed, incorporating planar PCB winding technology to optimize the design of planar transformers, inductor windings, and copper thickness for reduced size and lower losses. Considering practical application requirements, a wide input voltage range was engineered, and a digital power controller, UCD3138, was selected to facilitate high-speed digital feedback. A comprehensive fault protection design for the full-bridge DC/DC power supply module was introduced, encompassing various protections including voltage, current, and temperature. Ultimately, a prototype was developed with rated power of 2 kW, rated input voltage of 270 V, an allowable input voltage range of 200 V to 400 V, and rated output voltage of 28 V.