A Two-Stage Isolated Converter without Intermediate Capacitor for Wide Voltage Range Applications

This paper presents an improved two-stage Three-Level Buck (TL-Buck) and LLC cascaded converter for wide input voltage range applications. With the three-level Buck structure as the pre-regulated stage, high voltage stress for the input switches can be alleviated. Compared with the traditional cascaded topology, the proposed topology removes the intermediate capacitance resulting in the front stage being equivalent to a current source. To verify the performance and design of the proposed converter, a 200W prototype is built, and preliminary experimental results are provided.