Induction motor speed estimation: limitations of certain neural schemes based on time instances of periodic signals

It is proved that certain induction motor speed estimation schemes based on tapped delay neural architecture have important limitations. If teaching data are collected as instances of periodic signals (such as voltages and currents) then accuracy of speed estimation cannot be improved above a certain level through sampling time selection, or enlarging number of delays of the input signals. Consequently frequency bandwith for which estimation can be used is also limited by accuracy of the signals amplitude measurement. For a fixed accuracy of measurement, better accuracy of speed dynamics estimation may be achieved at the expense of narrowing frequency band.