A Resonant Tertiary Winding-Based Novel Air-Core Transformer Concept

This paper presents a new concept of air-core transformers, which uses a resonant tertiary winding to create a strong coupling between the primary and secondary transformer windings. A large “magnetizing” impedance is achieved because of the resonance. Experimental and analytical studies are carried out on a toroidal air-core transformer to assess the effectiveness of the concept. The results show improvements in transformer performance when compared with the results from simple air-core transformers. The power loss caused by the resonant-winding resistance is identified as the main challenging issue for the proposed method. Since the proposed idea is developed and explained based on the three-winding transformer conventional model, the accuracy of the mathematical model is also verified and validated by the experimental tests.