Analysis and Verification on CLLC Resonant Bidirectional DC-DC Converter Based on Variable Frequency Phase Difference Control Principle

A Dual Active Bridge (DAB) converter controlled by phase difference or phase-shift control has several disadvantages such as soft-switching limitation and increase of reactive power under the condition of unbalanced two-port dc voltages. As an effective solution to those technical issues, Variable Frequency Phase Difference Control (VF-PDC) for a symmetrical series Resonant tank (CLLC)-applied Bidirectional DC-DC converter (RBDC) is newly developed, and its performances on soft-switching and reactive power reduction are analyzed theoretically and demonstrated by a experiment of the prototype.