微型大气电场监测装置的设计与实现

Design and implementation of monitoring device for miniature atmospheric electric field

针对户外场磨式地面电场仪存在的输入阻抗高、感应电流信号弱、易受外界电磁波干扰、功耗大且无市电供电等问题,设计一种光伏发电加蓄电池储能供电的低功耗大气电场监测装置。为减小系统功耗,提高测量精度,设计微型低速双定子差分式电场传感器,传感器感应到的两路微弱电流信号经过T型反馈网络实现I/U变换。通过减法器和4 Hz低通滤波器消除共模干扰和工频干扰,提高信号的信噪比。利用光传感器采集同步感应信号,与AD630锁相放大器配合对信号进行处理,得到与场强成正比例关系的直流电压。经实验验证,系统在–50~50 kV/m的模拟电场强度范围内,测量分辨力可达到10 V/m,测量线性度<1%。所设计系统能够在光伏供电的情况下独立运行,实时测量大气电场强度并将测量结果传输到上位机,为雷电监测预警提供必要的数据支持。

To solve the problems of high input impedance,weak induced current signal,susceptibility to external electromagnetic wave interference,large power consumption,and no mains power supply for outdoor field mill ground electric field meters,a low power atmospheric electric field monitoring device with photovoltaic genertion and battery energy storage is designed.In order to reduce the power consumption of the systerm and improve the measurement accuracy,a miniature low-speed dual-stator differential electric field sensor is designed.The two weak current signals received by the sensor undergo I/U conversion through a Tshaped feedback network.The interference caused by shared mode and power frequency is eliminated through the subtractor and 4 Hz low-pass filter to improve the SNR(Signal to Noise Ratio).The photoreceptor is used to collect the synchronous induction signal,and cooperates with the AD630 lock-in amplifier to process the signal to obtain a direct voltage proportional to the field strength.It has been verified by experiments that the system has a measurement resolution of 10 V/m and a linearity of<1%in the simulated electric field strength ranging from−50 kV/m to 50 kV/m.The designed system is able to operate independently whith photovoltaic power supply.Moreover,it can measure the atmospheric electric field strength in real time and transmit the measurement results to the upper computer,providing necessary data support for lightning detection and early warning.