摘要
该文设计了一种低频信号总谐波失真(THD)测量系统,被测信号的频率范围是0.1~1000 Hz。系统以嵌入式处理器和可编程逻辑器件为控制核心,结合过零比较器及电平变换电路,获得被测信号的周期和起始过零点,然后对该信号进行整周期同步采样。结合THD的定义并利用快速傅里叶变换(FFT)算法对采样得到的数据进行处理,进而得到被测信号的THD值,同时利用液晶屏显示被测信号整周期的波形。可编程逻辑器件主要作用是对比较器输出的方波进行自适应消抖处理,进而使得被测信号频率下限可达0.1 Hz。实测结果表明系统运行稳定,可以实现低频信号THD的测量,具有较好的应用前景和实用价值。
A total harmonic distortion(THD)measurement system for low frequency signal is designed to measure the signal at the frequency range of 0.1~1000 Hz.The embedded processor and the programmable logic device are used as the system controller,the period and the starting zero-crossing point of the measured signal can be obtained by zero-crossing comparator and level translation circuit,and then processing this signal by integer-period synchronous sampling method.According to the definition of THD,the sampled data is processed by Fast Fourier Transform(FFT)algorithm to obtain the THD value of the measured signal,and the whole period waveform of the measured signal is displayed on the LCD screen.The main function of programmable logic device is to process the square wave output from the comparator by adaptive elimination buffeting,so that the limit of detection of the measured signal frequency can reach 0.1 Hz.The experimental results show that the system runs stably and can measure THD of low frequency signal,and has good application prospect and practical value.
作者
赵二刚
王艳芳
张维
ZHAO Er-gang;WANG Yan-fang;ZHANG Wei(College of Electronic Information and Optical Engineering,Nankai University,Tianjin 300071,China)
出处
《自动化与仪表》
2019年第12期53-56,60,共5页
Automation & Instrumentation
基金
南开大学2017年实验教学课程改革项目(17NKZZYQ01)
关键词
总谐波失真测量
整周期同步采样
快速傅里叶变换
自适应消抖
total harmonic distortion(THD)measurement
integer-period synchronous sampling
fast fourier transform
adaptive elimination buffeting
