Increasing the measurement accuracy of GMR current sensors through hysteresis modeling

A method is presented for increasing the measurement accuracy of GMR (giant magnetoresistive) sensors by numerically eliminating the hysteresis in the output signal. A simplified mathematical model of the hysteresis has been derived from the T(x) hysteresis model for anticipating the measurement values. The model has been implemented in a software simulation environment and compared with real GMR sensor measurements, with very good results. Further, the model has been quantised and implemented on a fixed-point digital signal controller (DSC), connected to the output of the sensors. The linear output characteristic delivered in this case by the DSC confirmed the accuracy of the hysteresis model in the hardware implementation too. An algorithm based on the model has also been developed in order to eliminate error propagation during the measurements.