基于DDS技术的脉冲涡流检测激励源研制

Development of Pulsed Eddy Current Testing Excitation Source Based on DDS Technology

为提升现有脉冲涡流仪器激励源性能,提高检测灵敏度,利用直接数字频率合成技术的高分辨率、输出任意波形等优点和FPGA可编程特性,研制出可调式脉冲涡流仪器激励源。激励源以FPGA为核心,在D/A、滤波器及上位机等配合下,压缩存储波形数据较好地解决了相位截断引起的杂散问题,能够产生幅值、频率、占空比和边沿时间连续可调的激励信号。实验表明该激励源能输出参数可调正负方波,无明显毛刺,性能稳定,上位机界面友好,能满足脉冲涡流检测对激励源的要求。

In order to improve the performance of the existing pulsed eddy current instrument excitation source and improve the detection sensitivity,taking advantages of high frequency resolution and arbitrary waveform output of the direct digital frequency synthesis technology and the programmable characteristics of FPGA,the adjustable pulsed eddy current detection excitation source was developed.The excitation source takes FPGA as the core.With the cooperation of D/A,filters,and host computer,the compressed storage waveform data can solve the spurious problem caused by phase cutoff and can generate amplitude,frequency,duty cycle,and edge time.Experiments show that the excitation source can output positive and negative square wave with adjustable output parameters,the waveform is with no obvious burr,and stable.The interface of the host computer is friendly and can meet the requirements of pulse eddy current testing on the excitation source.