Control Strategy of Triple-Active-Bridge Converter for Bipolar DC Microgrid

The main assignment of a bipolar dc microgrid is the settlement of the bipolar voltage imbalance due to unbalanced loads and asymmetric powers. It is necessary to consider maintaining the bipolar systems whether in grid-connected mode or islanded mode of the microgrid. This article introduces the control strategy of the triple-active-bridge (TAB) converter for the bipolar dc microgrid by voltage balancing. The presented control strategy performs PN voltage regulation and voltage balancing based on the interrelation analysis between power and voltage in the bipolar dc microgrid. With the separately configured voltage balancing loop in the controller, the active voltage balancing through the power transfer between the bipolar buses is ensured even in the islanded mode without additional circuit components. The TAB converter operates with phase-shift modulation as conventional, and the control strategy is implemented through the digital signal processor. The validity of the proposal is verified by lab-scale experimental results.