Another important application of the DAB-based dc-dc converter system is the PPP converter system. Although the PPP converter systems are extensively studied for connecting the renewable energyRenewable energy source and the strong ac grid system, the PPP converter system for the islanded dc microgridIslanded DC microgrid still needs study. Therefore, a DAB-based PPP converter systemDAB-based PPP converter system is proposed for realizing the independent control of the renewable energy source and the stabilization of the total dc-link voltage in this Chapter. Generally, the renewable energyRenewable energy source should feature the current output and the limited requirement of the output-voltage regulation, such as PV, fuel cell and wind turbine with ac-dc conversion. Moreover, to deal with the disturbances such as the change of battery voltage, the variation of the renewable energy source and the load condition, a high-robustness controlHigh-robust control scheme is proposed for maintaining the total dc-link voltage in this Chapter. Furthermore, by using the PV as an example, the effectiveness of the proposed DAB-based PPP converter systemDAB-based PPP converter system and the proposed high-robustness control scheme is discussed and analyzed.