Model Building and Current Sharing Analysis for IPOP Converter System Based on Two-Stage LLC Resonant Converter

The two-stage LLC resonant converter has been widely used in wide voltage matching occasions. However, the errors of resonant parameters can cause considerable power imbalance between cascading modules in the input-parallel output-parallel (IPOP) converter system. In this paper, a parallel current sharing model considering parasitic resistances is established and the steady-state operating points of the parallel modules is solved. Further, the mechanism of resonant elements on the current sharing characteristic is revealed. Finally, a prototype including two 1-kW 28-V boost + LLC resonant converters is built to verify the theoretical analysis.