EPECentre Seminar Series

Trapezoidal Current Generator for an Electromagnetic Groundwater Flowmeter


Dr Bill Heffernan, Senior Research Engineer, EPECentre, University of Canterbury


A return-to-zero, bipolar, trapezoidal current generator for driving the coil of a prototype electromagnetic groundwater flowmeter is described. Operation of the circuit, which employs a laboratory DC power source, a MOSFET H-bridge, some ancillary components and a microcontroller-based control system, is analyzed, simulated and practically demonstrated. Although the circuit can produce acceptable results, we show that it is sensitive to component tolerances and timing jitter and is inherently limited in realizable efficiency.