Research on the Core Loss of LLC Converter Transformer Based on Similarity Principle

Transformer is an important component of DC switching power supply. An optimal design is increasingly valued for high frequency and high power density of switching power supply. In the magnetic components of LLC resonant converter, the parameters of transformer are cumbersome, and the existing loss models are not good enough to provide accurate calculation results. Aiming at the above problems, this paper proposes a method to establish a transformer scaling model based on the similarity theory, by deriving the scaling relationships between different models. With the premise of ensuring the same working state between the original model and the scaling model, the scaling relationships of air gap length, magnetic flux density and core loss are calculated. Then, a finite element simulation model of the LLC converter transformer is established to verify the correctness of the scaling relationship of each parameter. After obtaining one form of transformer, the electrical characteristics of other transformers can be deduced, which provides a new method and tool for further optimization of transformer design.