In this paper, a self-synchronization mechanism is embedded into the universal droop controller\ud (UDC), which is applicable to inverters having an impedance angle between −π/2 rad and π/2 rad,\ud to form a self-synchronized UDC (SUDC). Both the voltage loop and the frequency loop of the UDC are\ud modified to facilitate the standalone and grid-connected operation of inverters. Importantly, the dedicated\ud phase-locked-loop that is often needed for grid-connected or parallel-operated converters is removed. The\ud inverter is able to achieve synchronization before and after connection without the need of a dedicated\ud synchronization unit. Since the original structure of the UDC is kept in the SUDC, the properties of the\ud UDC, such as accurate power sharing and tight output voltage regulation, are well maintained. Extensive\ud experimental results are presented to demonstrate the performance of the proposed SUDC for a gridconnected\ud single-phase inverter.