Bidirectional CLLC Converter Using A Hybrid Control Method for Wide Voltage Range Applications

To achieve a wide voltage range for battery applications, this paper presents a hybrid control strategy combining DC-link voltage (DCV) control, pulse-frequency modulation (PFM), and phase-shift modulation (PSM) for a bidirectional CLLC resonant converter. Additionally, a constant turn-on delay (CTOD) method is proposed for synchronous rectifiers (SRs), reducing control complexity. In this paper, a digital signal processor (DSP)-based bidirectional full-bridge CLLC resonant converter with SRs was constructed, featuring a wide voltage range of 360 V to 400 V on the high-voltage side and 36 V to 60 V on the low-voltage side. Operating in constant current (CC) charging mode, the CLLC converter achieves a peak efficiency of 97.9% at 2.5 kW and 60 V on the low-voltage side, demonstrating the effectiveness of the proposed hybrid control method. Furthermore, the bidirectional performance and smooth mode transition between different control modes are verified through the experimental results.