Bypass Self-Calibration Technique for Tunnel Magnetoresistance Current Sensor
The sensitivity of tunnel magnetoresistance(TMR)current sensor applied in smart power grid is easy to change under the influence of ambient temperature,which will seriously affect the measurement accuracy of TMR current sensor.Based on the basic measurement principle of TMR current sensor,the sensitivity of the sensor chip is analyzed theoretically.Adding a periodic injection DC self-calibration loop below the sensor,the average value of the difference between the output voltage of the sensor before and after injection can be calculated,and the real value of the sensitivity under the current ambient temperature can be tracked and calibrated in real time,and the closed-loop operational control circuit is designed to adjust the sensor in real time.Finally,the DC injection experiment,temperature control experiment and linearity experiment are carried out on the experimental testing platform.The test results prove that bypass self-calibration technology can improve the accuracy and stability of open-loop TMR current sensor measurement.
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