差分式TMR微弱电流传感器设计及其应用研究

Design and Application of Differential TMR Weak Current Sensor

为满足电力系统内变压器铁芯接地电流等微弱电流测量应用需求,文章开展差分式隧道磁阻技术(tunnel magneto-resistance,TMR)微弱电流传感器研究,基于双端差分式测量模式可抗外部磁场干扰的原理,设计包含聚磁体、磁阻芯片,差分放大电路、模数转换电路、主控单元电路、数据传输电路和电源电路等结构的TMR微弱电流传感器。测试结果表明,在±2.5 A测量范围内传感器的输出线性度良好,最大误差不超过1%±1 mA,分辨力不小于1 mA。在外部低频干扰情况下,相较于单端测量模式,双端差分测量模式可大幅降低干扰影响。所研究的传感器具有较好的线性度、精确度、抗外部干扰等优点,能够为电力系统新型感知业务提供量测基础,进而为能源互联网数字化建设提供技术支撑。

In order to meet the application requirements of weak current measurement such as transformer core grounding current in power system,this paper carries out the research of differential TMR(tunnel magneto resistance)weak current sensor.Since the two-terminal measurement mode can resist the interference of external magnetic field,a TMR weak current sensor with the magnetism gathering structure,magnetoresistive chip,differential amplifier circuit,analog-to-digital conversion circuit,main control unit circuit,data transmission circuit and power supply circuit is designed.Tests show that the sensor developed in this work performances well with good linearity of outputs within the measurement range of±2.5 A,and the maximum error is no more than 1%±1 mA,and the resolution is no less than 1 mA.In the case of external low-frequency interference,compared with the single terminal measurement mode,the double terminal differential measurement mode proposed in this paper can evidently reduce the interference impact.The sensor studied has the advantages of good linearity,accuracy,and anti-external interference.It can provide measurement basis for new sensing business of power system,and then provide technical support for the digital construction of energy Internet.