Abstract: As the proportion of photovoltaic power generation increases rapidly,the controller of photovoltaic grid-connected inverter needs to obtain the amplitude and phase of the common coupling voltage point from the PLL. When it is in the weak power grid or the power grid voltage sensor fails,the PLL will be unstable,which greatly increases the control difficulty of the inverter. Based on this,this paper proposes a method of grid voltage estimation and control of photovoltaic inverter based on internal mode principle,which realizes common coupling voltage estimation and unit vector generation by using current measurement and nominal values of filter parameters. The robustness analysis shows that the proposed control and estimation methods are almost insensitive to parameter changes. Compared with traditional current control using voltage and current sensors,the proposed control scheme can provide better transient response capability under both ideal and non-ideal grid voltage conditions. Finally,experiments on a small laboratory prototype demonstrate the effectiveness of the proposed method.