O. Vainio et Sj. Ovaska, NOISE-REDUCTION IN ZERO-CROSSING DETECTION BY PREDICTIVE DIGITAL FILTERING, IEEE transactions on industrial electronics, 42(1), 1995, pp. 58-62
A simple combination of nonlinear and linear digital signal processing
methods is proposed for efficient noise reduction in zero crossing de
tectors. The method is very robust against strong impulsive noise, typ
ically encountered in thyristor power converters, where reliable zero
crossing detection is required for firing synchronization. A systemati
c design procedure is described for the proposed filter-based synchron
ization method, taking into account the specified line frequency toler
ance. The fully digital signal processing approach allows compact impl
ementations, and supports flexible interfacing to digital motor contro
l systems.