一种采用压电复合音叉的电流传感器研究

Research on a Novel AC Current Sensor Using a Piezoelectric Composite Tuning-Fork

针对当前非接触电流测量方式存在的灵敏度低、结构复杂等问题,本文提出了一种采用压电复合音叉的电流传感器用于非接触低频微弱电流测量,其结构由永磁体、弹性音叉、压电片及底座组成。当该传感器处于电线周围交变磁场中时,永磁体在磁场作用下产生扭矩并驱动弹性音叉臂及压电片产生形变;因压电效应,形变的压电片两端电极之间输出交变电压信号,从而实现电流的测量。由于磁扭矩效应,这种传感器具有较高的谐振灵敏度,大约是压电悬臂梁式电流传感器的4.0倍;在负载电阻为10 MΩ、频率为41.7 Hz时,灵敏度可达1.393 V/A,线性度约为0.57%。这种压电复合音叉式电流传感器模型还可以应用于微弱振动、磁场信号探测等。

The conventional non-connect measurement strategy for AC current shows low sensitivity and complex structure.In order to enhance the measurement sensitivity at low-frequency,a current sensor using a piezoelectric composite tuning-fork is presented,which consists of permanent magnets,an elastic copper tuning fork,piezoelectric PZT plates,and a pedestal.When the sensor is situated in the magnetic field induced by AC current in the power transmission line,the magnetic torque applied on the permanent magnet appears,and drives fork beams and PZT plates to bend.Therefore,alternating voltage signal produces across the electrodes of PZT plate,and thus the input current in power transmission line can be obtained by the relation between input current and output voltage.Due to the great magnetic torque effect,the presented sensor behaves high sensitivity which is about 4.0 times greater than that of the traditional sensor using a piezoelectric cantilever.The experiments show the sensor has a resonant sensitivity of^1.393 V/A and a linearity of^0.57%with the load resistance of 10 MΩat the frequency of 41.7 Hz.The proposed sensor can be further used in the fields of vibration and magnetic signal detection.