A Novel Concept to Optimize Core Loss in Planar Magnetic Based on an Unbalanced-Flux- Approach

This paper presents a new method to design planar magnetics. Unlike existing magnetics which have a balanced-flux distribution, the proposed method is based on the principle of unbalanced-flux distribution. The Steinmetz model, derived for this design principle, shows that the unbalanced-flux method reduces the core loss by more than 50%. The core loss reduction brings several benefits to planar magnetics such as: high magnetic power factor, better thermal performance and larger safe operating area (SOA). The proposed method is experimentally evaluated and compared with the balanced-flux method. The obtained results confirmed the advantages of the unbalanced-flux method found from the theoretical study. The core loss is decreased by more than 50%, the magnetic power factor is increased by 73% and the SOA is much larger.