Robust zero-crossing detection of distorted line voltage using line fitting

Zero-crossings of sinusoidal signals are used for synchronization of the system, especially in many power electronics applications. A novel adaptive method for detecting zero-crossing and measuring the line frequency is proposed. This approach thrives on the linearity of a sinusoidal wave near zero-crossings. The proposed technique incorporates an initial multistage filter, followed by a line fitting model and finally, the extrapolation of the zero-crossing point which compensates for the delay incurred during the process of filtration and linearization. This digital signal processing approach is computationally efficient and easy to implement and is ideal for systems with fast changing frequencies. The simulation results presented in this paper show the competitive performance of this approach.