一种隧道磁电阻电流传感器的旁路自校准技术

Bypass Self-Calibration Technique for Tunnel Magnetoresistance Current Sensor

应用于智能电网的隧道磁电阻(tunnel magnetoresistance,TMR)电流传感器的灵敏度易受环境温度的影响发生变化,从而严重影响TMR电流传感器的测量精度。从TMR电流传感器基本测量原理出发,对传感器芯片的灵敏度进行了理论分析。在传感器下方增设了周期注入式直流自校准回路,计算注入前后传感器输出电压的差值平均值,实时追踪校准当前环境温度下灵敏度的真实值,并设计闭环运算控制电路对传感器进行实时调整。最后搭建实验测试平台进行了直流注入实验、温控实验和线性度实验,测试结果证明了旁路自校准技术可以提高开环式TMR电流传感器测量的准确性和稳定性。

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.