Extracting RMS of single phase signal - using two auxiliary valves proportional to original voltage or current but phase shifted by 45 degrees

摘要

A simple arrangement of operation amplifiers is presented for extracting the root mean square value of a single phase a.c. or voltage signal. The circuit is intended for use in control networks where one of these parameters might be the controlled variable. Basically, the incoming signal (m(t)) is fed to two phase shifting circuits one of which produces a position, and the other a negative 45 deg. degree phase shift. These, in turn, feed squaring circuits a summing amplifier (53) and a square root extraction circuit. The basic phase shifting network entails two interlinked operational amplifiers.