Battery monitoring current sensors ::the fluxgate concept

One of the difficulties concerning battery monitoring applications is the current measurement. Typically the measurement range (DC) can vary from 10 mA up to 1000 A. Today's available current transducers are not well adapted to work with good accuracy in this very large domain. In this paper a new measurement principle based on a technology of type ldquofluxgaterdquo [1] is presented, which allows reaching a wide measurement range while guaranteeing an excellent accuracy. The key idea is to use the magnetic field created by the primary (battery) current acting on a saturable inductor. By measuring the intervals to reach inductor saturation and the load current and making use of a suitable microcontroller it is possible to accurately evaluate the value of the primary current for both high and low current levels.