**6. Conclusions**

The Split-pi converter is a good choice to integrate an energy storage system (ESS) into a DC microgrid. In part I of this work, five typical microgrid scenarios were identified. Each of them required a specific state-space model of the Split-pi and a suitable control scheme. Two different state-space models were devised for the Split-pi converter operating with lower storage-side voltage than grid-side voltage. Such models considered the parasitic elements of the converter. In addition, the most relevant transfer functions were given, together with control schemes with a different number of control loops and criteria to design the controllers.

The present paper completed the study validating the theoretical analysis based on comprehensive simulations and experimental tests. A 48 V, 750 W storage system interfaced with a 180 V DC microgrid using a Split-pi converter was chosen as a case study. It can represent a reduced-power prototype of terrestrial and marine microgrids. Several simulations were performed to assess the system performance in all the considered scenarios. Furthermore, a prototypal Split-pi converter was realized, and experimental tests were performed in conditions that covered all the scenarios. The obtained results were coherent with the simulations and validated the study.

Further activities will include theoretical studies and experiments with a twofold aim: (1) to devise the state-space model of the Split-pi operating with higher storage-side voltage than grid-side voltage; (2) to investigate the possibility of designing unconventional control systems for the Split-pi that are suitable for operating in more than one microgrid scenario.

**Author Contributions:** Conceptualization, M.L., A.S., M.P. and M.C.D.P.; methodology, M.L., A.S. and A.A.; software, M.L., A.S., A.A. and G.L.T.; validation, M.L., A.A., M.C.D.P. and M.P.; Writing— Original draft preparation, M.L., A.S. and M.P.; Writing—Review and Editing, M.L., A.A., M.C.D.P. and G.L.T.; supervision, M.P. and M.L.; funding acquisition, M.P. and M.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Italian Ministry of University and Research (MUR), program PON R&I 2014/2020-Avviso n. 1735 del 13/07/2017-PNR 2015/2020, project "NAUSICA-NAvi efficienti tramite l'Utilizzo di Soluzioni tecnologiche Innovative e low CArbon," CUP: B45F21000680005.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
