Accurate and fast estimation of magnitude, frequency, and phase of the grid voltage is an essential part of the synchronization process and power-sharing control among parallel connected inverter-based AC microgrids, while running in islanded mode. Synchronization can be done using both open-loop and closed-loop estimation techniques. The conventional closed-loop synchronization technique used is Synchronous Reference Frame based Phase Locked Loop (SRF-PLL), estimates the phase angle of the grid voltage with a typical settling time of one or multiple fundamental periods. Moreover, the SRF-PLL estimates both, the frequency and phase angle of the voltage in one single loop, thus a jump in the phase angle affects the frequency estimation, which will have a negative impact on the power sharing control. To overcome these issues, this paper proposes an open loop synchronization technique based on Teager-Kaiser Energy Operator (TKEO) and Cross Energy Operator (TKCEO) to estimate the grid voltage frequency and phase angle, respectively. Presented results show that the power-sharing with energy operator based calculations gives a better response when compared to classical SRF-PLL.