Power flow decoupling method of triple-active-bridge converter for islanding mode operation in DC microgrid systems

A single multiwinding transformer-based triple-active-bridge (TAB) converter with high power density is a viable candidate for DC microgrid development. However, it comes with a power flow challenge where all the ports are coupled. A power flow decoupling method is proposed for applications of the TAB converter in this paper. The method uses a combination of Proportional Integral (PI) controllers and a lookup table (LUT) that stores decoupling matrices for dynamic decoupling. The proposed decoupling method considers port voltage variations and utilizes only two control variables for voltage regulation. It is designed for application in the islanding mode operation of DC microgrids for DC bus voltage regulation. The feasibility and effectiveness of the proposed power flow decoupling method are verified by simulations and experimental results using an implemented 2 kW TAB converter prototype. Finally, the proposed method shows a 98.95 and a 99.00% improvement in power decoupling according to load variations in the load port.