考虑边缘和寄生电容的微加速度计的非线性误差研究
Research on Nonlinear Error of Micro-accelerometers Considering the Fringe and Parasitic Capacitance

为了使微加速度计满足线性度指标,准确计算微加速度计的非线性误差是非常必要的。在考虑边缘和寄生电容的前提下,提出了计算微加速度计的非线性误差的方法。首先根据表芯结构的电容分布特点建立了其等效电路模型,并推导了微加速度计的输出电压与检测电容和寄生电容之间的关系式,其中检测电容包含了边缘电容;其次,基于有限元法,分别提出了计算微加速度计的寄生电容和检测电容的方法;最后建立了微加速度计的输出电压与输入加速度之间的关系式,并基于三次多项式拟合,推导出微加速度计的非线性误差的计算公式。通过对比分析非线性误差的理论计算结果与实验测量结果,提出的方法的正确性得到了验证。
In order to make the micro-accelerometers satisfy the specification of linearity, it is very necessary to calculate the nonlinear error of micro-accelerometers accurately. A method for calculating nonlinear error that taking the fringe capacitance and parasitic capacitance into consideration is proposed in this paper. At first, the equivalent circuit model of micro-accelerometers is established on the basis of distribution characteristics of capacitance, and the formula connecting the voltage output with measuring capacitance and parasitic capacitance is derived, where the fringe capacitance is included in the measuring capacitance. Then, based on the finite element method, the methods for calculating the parasitic capacitance and measuring capacitance are proposed respectively. Finally, the relation between the output voltage and the input acceleration of micro-accelerometers is established, and the formula for nonlinear error of micro-accelerometers is derived based on the cubic polynomial fitting. By comparing the theoretical results and the experimental results of nonlinear error, the correctness of the method proposed in this paper is demonstrated