Grid voltage estimation and current control of a single-phase grid-connected converter without grid voltage sensor

This paper investigates the possibility of estimating the grid voltage and controlling a single-phase grid-connected converter without a dedicated grid voltage sensor. The main focus is given to current-controlled architectures which need phase-locked loops (PLL) for their operation. The grid voltage estimation method is proposed based on the active and reactive power delivered by the converter to the grid. In addition to the estimation of the grid voltage, the proposed method also generates the unit vectors and frequency information similar to a conventional PLL structure. The influence of various parameters like the dead time, equivalent loss resistance, and the filter inductance on the proposed estimation method is studied in details. Experimental results validate the feasibility of the proposed scheme.