Integrated Current Balancing Transformer Based Input-Parallel Output-Parallel LLC Resonant Converter Modules

Input-parallel output-parallel (IPOP) connected converter system allows the use of low power converter modules for high power applications. In this paper, a reliable integrated current balancing transformer (ICBT) is proposed for the current balancing requirement of IPOP LLC resonant converter modules. The proposed ICBT based IPOP LLC resonant converter modules ensures both input current sharing (ICS) and output current sharing (OCS) in constituent modules, without dedicated controller. The proposed ICBT is basically the resonant inductors of LLC resonant converter modules, coupled to perform the function of current balancing, and also have enough leakage inductance for resonance operation simultaneously. Moreover, the proposed ICBT can significantly reduce the overall magnetic volume, and increase the power density of IPOP LLC resonant converter modules. Magnetic and electrical models of the proposed ICBT have been presented in this paper. To validate the performance of the proposed ICBT based IPOP LLC resonant converter modules, a 2.5 kW hardware prototype has been designed, fabricated and tested successfully.