地面静电加速度计的位移检测电路设计

高精度静电悬浮加速度计可作为海空重力测量仪器中的核心传感器，检验质量的位移检测电路是加速度计控制系统的核心，其精度直接影响了加速度计零偏和标度因数的稳定性，因此需要研究分辨率高、噪声小的位移检测系统。针对高精度静电悬浮加速度计的地面应用需求，以大表面积质量比的敏感探头结构为测量对象，设计了基于差动电容的位移检测电路，建立了电容检测电路的数学模型，对电路误差源进行了系统分析。实验结果表明，该电路能够有效地抑制悬浮高压引入的耦合误差，减小电路噪声。当电路工作在零点附近，20kHz内的噪声小于2×10-6V/Hz1/2，对应电容检测分辨率为2.93×10-5pF/Hz1/2，能够满足地面应用静电加速度计对位移测量精度的要求。

Design of Displacement Detection Circuit for Electrostatically Suspended Accelerometer in Full Earth Gravity

As one of the required key sensor in sea-air gravimetry, electrostatically suspended accelerometers(ESA) is in demanding need of its high-accuracy. Among which, a proof mass''s displacement detection circuit with high-resolution and high-stability is specified because of its direct effect on bias and scale factor stability of the ESA. To fulfill the surveys in air-sea gravity, a differential displacement detection circuit based on transformer and Wheatstone bridge theory has been developed for an ESA of which proof mass has large ratio of surface area to weight. The mathematical model of the capacitance detection circuit has been established and the source of the circuit error has been analyzed. The experiment shows that the circuit can effectively suppress the error introduced by the high control voltage and reduce the circuit noise and drift. It shows the circuit''s null position noise is less than 2×10-6V/Hz1/2 in 20kHz, and capacitance detection resolution is 2.93×10-5pF/Hz1/2 which can meet the requirements of ESA for displacement measurement accuracy.