Error analysis of a dual-VFC multiplier aimed at industrial-frequency power metering

This paper presents the error analysis of a multiplier built with two cascaded voltage-to-frequency converters (VFC), aimed at industrial frequency power metering. The error sources were identified and quantified, and it was found that the major error source is the offset frequency term. The VFC response to a varying input frequency was also investigated, and no misbehaviour was detected. A simple modification that cancels the offset-frequency error is proposed. With this modification, accuracy better than 1% was obtained in laboratory tests.