Investigation Of Tunneling Magnetoresistance Based Open Loop Current Sensor

Tunneling magnetoresistance(TMR)was greatly focused by investigators in all the world due to its high sensitivity and wide frequency response range for MR technology.Specifically,TMR can be driven by very low power with wide resistance variation range also with good linearity.It can be ideally applied to current sensor application.However,the key parameters for the field sensing based on the TMR sensor in laboratory have quite large difference from the theoretic value due to the structure design.In this work,a TMR based digital current sensor was selected as the object for study.It shows a great improvement of the accuracy for the current measurement by optimizing the structure of the sensor and the electronic circuit design.The performance of the current sensor was verified in laboratory based on international standard IEC61036 and National standard GB/T17215.Moreover,the influences of ambient temperature and magnetic field on the sensor performance were also investigated.The study showed that such a TMR based open-loop digital current sensor performs great dynamics and high linearity properties.However,the ambient temperature and magnetic field will still have a heavy influence on its properties.