Digitally controlled bipolar converter for DC micro grids

Abstract

This paper proposes a digitally controlled bipolar converter for dc micro grids. The bipolar converter configuration is based on the combination of SEPIC and CUK converter with the modifications in both the converters. In the proposed bipolar converter, the equivalent series resistance (ESR) of the transfer floating capacitor is increased by inserting a series resistance in the both SEPIC and CUK converter and magnetically coupled inductors are used on both (input and output) sides of the SEPIC converter with damping network. Such type of arrangement eliminates right half zero (RHP) from the proposed bipolar converter and facilitates simpler controller design. The proposed bipolar converter is operated on field programmable gate array (FPGA) based digital current mode control for bipolar micro girds. The proposed concept facilitates regulated bipolar dc outputs and allows integration of renewable energy sources to bipolar micro grid. Thus, in view of the benefits of bipolar dc link, the proposed concept gives a solution to the requirement of distributed generation units with highly efficient, less costly and easy to implement. Detailed mathematical modeling and dynamic analysis is carried to take out the advantages of the proposed system. Simulation and experimental results are presented to verify the proposed algorithm.