Electrical and Computer Engineering Seminar Series

Trapezoidal Current Generator for an Electromagnetic Flowmeter


Dr Bill Heffernan


Electric Power Engineering Centre University of Canterbury

Time & Place

Fri, 06 Nov 2020 14:00:00 NZDT in Link 309 Lecture Theatre


One of the NZ Science for Technological Innovation (SfTI) National Science Challenge (NSC) Spearhead projects is entitled “Inverting electromagnetics – a new way to measure groundwater flow”. Electromagnetic flowmeters, based on the principle first suggested by Michael Faraday, are now commonplace in industrial applications, to quantify the flow of fluid in pipes. This project, led by Lincoln Agritech, with the involvement of UC, Robinson Research Institute and other collaborators has sought to adapt the principle to unconstrained water flow, in order to attempt to measure the flow of groundwater. Knowledge of this flow is becoming increasingly vital, as demands on water resources become more intense. The basis of the technique is to measure the small voltage produced by the charge redistribution of ions in the water flowing through a controlled applied magnetic field. There are many challenges associated with isolating the desired signal from interfering signal sources, but addressing these will require another seminar! The present talk will instead concentrate on the design and implementation of circuitry to drive a trapezoidal current waveform through a coil, to produce the optimum time-varying magnetic field.