基于巨磁阻效应的电流传感器密封式聚磁环设计

智能电网的建设离不开先进的传感和量测技术。相对于传统巨磁阻电流传感器聚磁环有开口的情况，文中提出了一种应用于巨磁阻电流传感器上的密封式聚磁环，包括对密封式聚磁环形状与构造、气隙开口大小与凹凸程度的设计，以及对密封式聚磁环所用的材料进行挑选。利用COMSOL Multiphysics对密封式聚磁环的模型进行仿真，对比分析了密封式聚磁环与传统式聚磁环之间的磁场饱和程度，气隙中心磁场均匀度的大小关系。仿真结果表明，密封式聚磁环的聚磁能力是传统开口式聚磁环的764倍，其结构能够使得巨磁阻传感器拥有更低的磁滞，灵敏度比传统开口结构磁环更好，从而可以为现场实时、精确、可靠的电流进行测量；小电流实验验证了密封式聚磁环在微弱磁场下的聚磁效果显著，0.2 A及其以下电流所产生的磁场经密封式聚磁环聚磁后作用于巨磁阻芯片上，密封后巨磁阻芯片输出的电压是密封前的5倍以上。

Design of sealed magnetic concentrating ring of current sensor based on giant magnetoresistance effect

The construction of a smart grid cannot be separated from advanced sensing and measurement technologies. Compared with the traditional giant magneto-resistive current sensor with an opening in the magnetic concentrating ring, this paper proposes a sealed magnetic concentrating ring applied to the giant magneto-resistive current sensor, including the shape and structure of the sealed magnetic concentrating ring, and the air gap opening. The design of the size and the degree of unevenness, and the selection of the materials used in the sealed magnetic concentrator. Using COMSOL Multiphysics to simulate the model of the sealed magnetic concentrator, the relationship between the magnetic saturation degree of the sealed magnetic concentrator and the traditional magnetic concentrator and the uniformity of the magnetic field at the center of the air gap was compared and analyzed. The simulation results show that the magnetic concentrating ability of the sealed magnetic concentrator is 764 times that of the traditional open magnetic concentrator, and its structure can make the giant magneto-resistive sensor have lower hysteresis and better sensitivity than the traditional open magnetic ring. It can be used for real-time, accurate and reliable current measurement in the field; small current experiments have verified that the magnetic concentrating effect of the sealed magnetic concentrating ring is remarkable under weak magnetic fields. The magnetic field generated by the current of 0. 2 A and below acts on the giant magnetoresistive chip after being concentrated by the sealed magnetic concentrating ring. The output voltage of the giant magnetoresistive chip after sealing is more than 5 times that before sealing.