High-Gain High-Efficiency IPOS LLC Converter With Coupled Transformer and Current Sharing Capability
Yucen Li
Abstract
In this paper, an input-parallel output-series (IPOS) LLC resonant converter with a coupled transformer and current sharing capability is proposed for high-gain high-efficiency applications such as the renewable energy grid connection. The coupled transformer is utilized to reduce the core size and core loss by implementing the magnetic flux cancellation method, which achieves a natural balance of output voltage simultaneously. The current sharing between the converter modules is achieved by a bridge wire that interconnects the resonant tanks of different modules. Furthermore, the current sharing inside a module is also achieved by the proposed compensation current based on the coordination of compensation inductor and delay control. A 200 kHz 100 V/1.2 kV 3.6 kW two-module IPOS LLC resonant converter prototype is built to verify the proposed method. The peak efficiency can reach as high as 97.5%, and the current sharing between modules and inside a module are well presented.