谐振式硅微加速度计闭环控制系统的分析与设计

Analysis and design of closed-loop control system for silicon resonant accelerometer

谐振式硅微加速度计以其准数字量输出和具有潜在高精度的特点,近年来成为硅微惯性仪表研制的热点之一。闭环控制是提高仪表精度水平的重要手段。以谐振式硅微加速度计的结构特性和电路特性为基础,分析了直流和交流两种幅值自动增益控制回路方案,比较了移相和锁相两种相位闭环控制方案。通过试验对比优选了交流幅值自动增益控制和锁相控制的双闭环系统控制方案。研制的谐振式硅微加速度计样机基频约为17 kHz,标度因数约为220 Hz/g,2 h零偏稳定性达到21.9μg.。

The silicon resonant accelerometer（SRA） has become a hot spot recently,due to its taking quasi-digital signal as output and the potential of high precision.The closed-loop control is one of the important ways to improve its performance.Based on the analysis of the characteristics of structure and circuits of the SRA,two schemes of magnitude auto gain control（AGC） were compared,and two kinds of phase closed-loop schemes of phase-shift and phase lock loop（PLL） were analyzed.The AC AGC and PLL were chosen as the final closed-loop system scheme of SRA through experiments.The natural frequency of the designed accelerometer is 17 kHz with a scale factor of 220 Hz/g,and the bias stability of SRA is 21.9 μg in 2 h.