Current Sharing Control of Interleaved LLC Resonant Converter with Hybrid Rectifier

The interleaving technique is required for LLC resonant converters to achieve high power level and handle higher input/output current. However, conventional pulse-frequency modulated (PFM) LLC converters face challenges of load current sharing due to component tolerances of resonant tanks. In this paper, a hybrid rectifier is employed in interleaved LLC converters to compensate the voltage gain of each module and achieve current sharing. By adopting an active switch in the conventional diode rectifier, the hybrid rectifier provides additional voltage-regulation ability, and thus good current-sharing performance can be achieved by regulating the duty ratio of the active switch slightly in the hybrid rectifier. Zero-voltage switching (ZVS) for all MOSFETs is achieved. The operational principle and characteristics of the presented converter are analyzed in detail. Experimental results are provided to verify the feasibility and demonstrate advantages of the current-sharing method.