A Novel Design for a 3.6KW LLC Transformer with Tight Tolerance, Primary Side Concentrated Leakage Inductance to Replace a Discrete Resonant Inductor for Improved EV/HEV Onboard Charger performance

摘要

The benefits of the LLC topology for multi-KW On Board Charger (OBC) applications are well understood with the resonant inductor facilitating zero volt switching operation. The LLC transformer leakage inductance can replace a discrete resonant inductor if the value can be correctly sized and with the required tight tolerance. A novel construction is presented to achieve these requirements. Finite element analysis modelling (FEM) demonstrates how this leakage inductance is concentrated on the primary side for optimized performance. This analysis is validated with transformer measurement data and further verified by converter performance.