A Transformer Design with PCB Litz Wire Concept for Solid State Transformer

Litz wire is known for its ability to minimize winding losses in high-frequency applications. However, its implementation in PCB winding poses significant challenges. This paper presents a novel PCB Litz wire concept aimed at minimizing winding loss in high-frequency applications, specifically in the design of a solid-state transformer using PCB-winding-based technology. The proposed PCB Litz wire is designed in a circular winding configuration with curved strands, optimizing its performance. The construction method and the turn-to-turn connection are demonstrated. Factors affecting the resistance of the PCB Litz wire, including the number of strands, their width, and section, are discussed. The results show that compared to traditional PCB winding, the PCB Litz wire achieves a 30% reduction in winding loss and significantly improves current distribution, leading to enhanced thermal performance. To validate the concept's effectiveness, a prototype of a 1.6/1.05kV, 190kHz, 30-kW CLLC converter is built, demonstrating an impressive 98.8% efficiency.