实现FTIR光谱仪动镜扫描的全数字控制研究

动镜扫描是导致FTIR光谱仪动态测量误差的主要因素，其运动的平稳性直接制约着测量光谱的信噪比，并影响到后续光谱定性定量分析的精度，对FTIR光谱仪整体性能优劣有举足轻重的作用。针对传统基于模/数混合设计的动镜运动控制系统的复杂性，研究了一种简洁实效的全数字控制方法，将动镜运动产生的正交编码信号A和B送入数字逻辑芯片CPLD，在该芯片内编写相应的位置和速度控制算法，生成两路PWM信号，再通过数字功率芯片驱动挂载动镜的音圈电机完成扫描。实验表明，该控制方法使动镜在匀速阶段的速度平均稳定性优于97.2%，可显著提高测量光谱信噪比，为FTIR光谱仪高精度定量分析提供保障。

The Realization of Moving Mirror Scanning in FTIR Spectrometer Using Completely Digital Control Method

In view of the complexity of the conventional control of scanning mirror based on a digital-analog hybrid design, this paper focuses on a concise and efficient control method around the completely digital signal. The quadrate-encoder pulses A and B generated by the scanning mirror were sent into CPLD pins where an algorithm on position control and velocity control had been built. As a result, the CPLD will generate two PWM signals. These two signals are regenerated by a digital power chip to drive the voice of motor bundled with the moving mirror. Experiments validated that the stability of velocity of moving mirror is better than 97.2% and the method can improve the SNR of the measured spectrum and guarantee the accuracy of spectral qualitative and quantitative analyses.