用于电流传感的声表面波磁致伸缩效应
Surface acoustic wave magnetostrictive effect for current sensing
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摘要: 利用声表面波(SAW)磁致伸缩效应可以实现一种快速、高灵敏度的电流检测方法,但磁致伸缩薄膜内部矫顽力导致了明显的磁滞误差。磁致伸缩薄膜的栅阵化设计可以减小磁致伸缩时薄膜内部矫顽力,抑制磁滞现象,从而实现高灵敏和低迟滞误差的SAW电流检测。结合有限元和耦合模理论对沉积铁钴(FeCo)薄膜栅阵的声表面波电流传感器中的磁致伸缩效应进行分析,对传感响应进行仿真,确定优化的传感结构参数。为验证理论分析,实验研制了频率为150 MHz的声表面波电流传感器件,并结合差分振荡电路及亥姆霍兹线圈,建立传感器测试系统.实验结果表明,磁致伸缩薄膜的栅阵设计大幅降低了迟滞误差,并显著提升了传感器灵敏度。Abstract: Surface Acoustic Wave(SAW) magnetostrictive effect provides a fast and highly-sensitive current detection method,but the coercive force inside the magnetostrictive film results in obvious hysteresis error of the sensor.The strippatterned design of magnetostrictive film can reduce the coercivity inside the film during magnetostriction and suppress the hysteresis phenomenon,so as to realize SAW current detection with high sensitivity and low hysteresis error.Based on the finite element method and Coupled Mode Theory(COM),the magnetostrictive effect of SAW current sensor with strip-patterned FeCo film is analyzed,the sensor response is simulated to determine the optimal structural parameters.To verify the theoretical analysis,the SAW current sensor with a frequency of 150 MHz is developed experimentally,and the sensor test system is established by combining the differential oscillation circuit and the Helmholtz coil.The experimental results show that the strip-patterned design of magnetostrictive film greatly reduces the hysteresis error,and significantly improves the sensor sensitivity.