A Parameter Design Method for Bidirectional LLC-C Resonant Converter for Bidirectional On-Board EV Charger Application

A detail design process is presented for a bidirectional LLC-C resonant converter which is applied in on-board charger (OBC). The switching frequency range of charge and discharge mode is very close by the proposed design method. Firstly, the fundamental harmonic approximation (FHA) and resonant network equivalence were used to rebuilt the gain model in both of directions. Based on the model, a design variable m represented the normalized frequency ratio in both of direction is introduced to simplify gain expression and benefit analysis. After a detail analysis for the effect of design variables, a parameter design method is presented. A nominal charge power 6.6 kW prototype is bult to verify the effectiveness and feasibility of theoretical analysis.