A Dual LC Interleaved Four-Port Converter for Bipolar DC Microgrids

In order to maintain the voltage balanced of the long bipolar low-voltage dc supply and utilization system, multiple distributed voltage balancers (VBs) are demanded. A four-port converter with dual LC balancing branches is proposed in this article to reduce the hardware cost of a distributed VB. The converter consists of two dual active bridges (DABs) and two LC balancing branches. The LC branches and DAB full-bridge circuits on the grid side form two interleaved LC VBs. The proposed converter integrates voltage balancing and device grid connection functions through a switch-sharing technology, which can effectively replace distributed VB. Most importantly, both functions of the converter can be operated simultaneously. In addition, interleaved LC VB can achieve smaller grid connected voltage ripple. All the switches of the converter turn ON with zero-voltage switching. The validity of the proposed converter is verified through +/- 375 V Simulink simulation and +/- 24 V down-scaled power experimental prototype.