Abstract:The interface impedance filters out harmonics and provides a voltage sensing point for inverter synchronization. However, interface impedance and voltage sensors increase the size, power loss, and complexity of the system. To address these problems, a virtual impedance-based voltage sensor-free control scheme is proposed to implement the inverter grid-connected. Firstly, the control system of the inverter is analyzed. Secondly, the principle of virtual impedance implementation is described, and the method of replacing the interface impedance with virtual impedance and removing the AC voltage sensor used for synchronization is proposed and investigated in detail, and a method of synchronization using a current sensor at startup is proposed. Then, to reduce the complexity of the system, a method of self-synchronization using only virtual resistors is proposed. Finally, Matlab/simulink simulations and experiments were performed to compare the results and verify the stability and dynamic characteristics of these methods.