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This study proposes a new three-port multidirectional DC-DC converter (TMC) to integrate an energy storage system (ESS) or main grid to a bipolar DC microgrid (BDCMG). This converter provides a voltage balancing function and controls the input and output power of the BDCMG so that during overload conditions injects power to the BDCMG and in low-load conditions saves the available power to an ESS or transfers to the main grid. Given this integration of activities, the total number of converters in the BDCMG can be decreased. This feature enables that the converter can be used in portable systems where the overall efficiency and weight of the system are important. In the study, the performance of the proposed converter is analysed. Simulation studies are performed and a BDCMG laboratory setup is implemented in order to evaluate the performance of the proposed TMC. 1How to cite this article: Ahmadi T. Voltage unbalances mitigation in bipolar DC microgrids using a novel three-port multidirectional buck-boost converter.

In the proposed Load balancing transformer, two additional coupling winding are placed in the secondary of each phase. One of these coupling windings is in series with the winding of other phase and this combination of windings is reversely paralleled with the secondary winding of the third phase. Under unbalanced load conditions, the unbalanced part of the load current, flows through the proposed combination of windings. In this way, the unbalanced part of the load current is distributed between all phases. The proposed topology for multi stage load balancing transformer is based on the ordinary load-balancing transformer. Finally, these topologies are simulated with MATLAB and the results are discussed.