基于巨磁阻效应的电流传感器研制

Research and Design of a Current Sensor Based on Giant Magnetoresistance Effect

通过叠合两个巨磁阻芯片构成差分式巨磁阻组件。差动结构能够改善电流传感器的零偏电压,抑制温度漂移。同时引入反馈电路构成闭环系统,有效地提高了传感器的输出线性度,因此提高了电流测量精度。分析了传感器的工作原理,给出了系统闭环传递函数,并进行电路仿真和有限元仿真,分析验证方案的合理性。制作了样机,实验结果表明,所研制闭环结构电流传感器能在±5 A的量程内线性工作,灵敏度为204.6 mV/A,线性度为0.30%FS,精度可达0.39%。

Two giant magnetoresistance chips are pasted together to form a differential giant magnetoresistance module. The differential structure can improve the zero bias voltage of the current sensor and restrain the temperature drift. At the same time, a feedback circuit is introduced to form a closed-loop system, which effectively improves the linearity of the output of the sensor and thus improves current measurement accuracy. The working principle of the sensor is analyzed. The closed-loop transfer function of the system is given. And the circuit simulation and finite element simulation are carried out to verify the rationality of the scheme. The prototype is fabricated. The experimental results show that the closed-loop current sensor can work linearly in ±5 A range. Moreover, the sensor has the advantage of high sensitivity, excellent linearity and high precision.