自积分式脉冲磁场传感器的补偿研究

A Compensation of the Self-integrating Magnetic Field Sensor

自积分式磁场传感器用于脉冲场测量时，普遍存在低频失真问题。本文提出一种数字滤波的方案对传感器的低频特性进行补偿。滤波器采用无限冲激响应滤波器的形式，并以系统辨识的方法直接在时域进行设计。应用结果表明，该滤波器能有效地修复失真波形，使传感器的响应特性得到显著改善。

In the measurernent of pulsed magnetic field,self- integraling magnetic field sensors have the problem of low frequency distortion. A digital filtering method is presented in this paper for the compensation of the low frequency characteristics of the sensors. Suppose that the measuring system is a linear and time invariant SISO system, the digital compensation filter in the form of infinite impulse response is in series with it. The digital filter is designed in time domain by establishing a differential equation model of the filter according to the speCified inputoutput waveforms. Experimental setups to acquire these input -output pairs are introduced, which include TEM cell,digital storage oscilloscope and personal computer. In the design process, a known magnetic field is produced in the TEM cell, which is set to be the output of the filter,and the waveform measured by the sensor is set to be the input o f the filter. Least square algorithm is used to estimate the coefficients of fiter models. To verify the effects of the compensation filter, Square wave response and double exponential wave response of the sensors are fed to the filter.Filtering results show that this filter can reconstruct the deformed waveforms effectively. Frequency domain analysis is also performed, from which we can see the filter has well improved the low frequency characteristics of the sensors.Some other distortion problems in the measurement have also been solved by the method of digital filtering described in this paper.