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.