Digital filtering for robust 50/60 Hz zero-crossing detectors

Author

Vainio, Olli ; Ovaska, Seppo J.

Author_Institution

Signal Process. Lab., Tampere Univ. of Technol., Finland

Volume

45

Issue

2

fYear

1996

fDate

4/1/1996 12:00:00 AM

Firstpage

426

Lastpage

430

Abstract

An improved digital filtering method for line frequency zero-crossing detectors is proposed. The multistage filter efficiently attenuates harmonics, wide-band noise, commutation notches, and other impulsive disturbances without causing any phase shift on the primary sinusoidal waveform. Our novel signal-processing system is a cascade of a median filter and an adaptive sinusoid predictor, followed by up-sampling and interpolation. The three-point median filter effectively removes impulses, and the predictor provides wide-band noise attenuation while compensating for delays in the other processing steps. The predictor adapts to possible line frequency variations within the specified range by changing the set of coefficients, based on an estimate of the instantaneous line frequency. The adaptive approach allows the use of highly selective IIR bandpass predictors

Keywords

IIR filters; adaptive filters; adaptive signal detection; band-pass filters; cascade networks; interference suppression; interpolation; median filters; quantisation (signal); signal processing equipment; signal sampling; synchronisation; 50 Hz; 60 Hz; adaptive sinusoid predictor; cascade; commutation notches; digital filtering method; harmonics attenuation; highly selective IIR bandpass predictors; impulsive disturbances; interpolation; line frequency zero-crossing detectors; median filter; multistage filter; noise reduction; quantisation; three-point filter; up-sampling; wide-band noise; Adaptive filters; Detectors; Digital filters; Filtering; Frequency estimation; Interpolation; Noise robustness; Phase noise; Power harmonic filters; Wideband;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.492760

Filename

492760