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.