一种基于锁相放大的谐振式密度传感器谐振频率测量系统设计  

Design of a Phase-Locked Amplification-Based Measurement System for the Resonant Frequency of Resonant Density Sensor

作　　者：李杏华[1] 李明璐 许斌[2] LI Xinghua;LI Minglu;XU Bin(School of Precision Instrument and Optical Electronics Engineering,Tianjin University,Tianjin 300072,China;Beijing Ruisai Changcheng Aeronautical Measurement and Control Technology Co.,Ltd.,Beijing 100176,China)

机构地区：[1]天津大学精密仪器与光电子工程学院,天津300072 [2]北京瑞赛长城航空测控技术有限公司,北京100176

出　　处：《传感技术学报》2024年第10期1659-1666,共8页Chinese Journal of Sensors and Actuators

基　　金：航空科学基金项目(20200003048001)。

摘　　要：谐振式密度传感器测量密度的关键在于谐振频率的测量。现有的测频法、测周期法、FFT法等谐振频率测量方法因噪声、脉冲误差等因素限制了其精度。为了解决该问题,设计了一种以锁相放大器为核心的谐振频率测量系统,其检测电路将交流振动信号的测量转换为直流恒定电压的测量。利用实验中发现的谐振区域内该直流电压与激励频率呈近似线性关系,基于扫频思想提出并实现了一种谐振频率自动测量算法。在(20±0.05)℃环境下进行了密度标定实验,对密度传感器进行了温度补偿。实验结果表明,在密度为700 kg/m^(3)~1000 kg/m^(3)的测量范围内,测得谐振频率稳定性可达到0.002%,传感器的密度测量最大误差为0.48 kg/m^(3),最大综合测量误差为0.069%,验证了所提谐振频率测量方法的有效性、精确性。The key of density measurement of resonant density sensor is the measurement of resonant frequency.The existing resonant frequency measurement methods,such as frequency measurement method,period measurement method and FFT method,have limited their accuracy due to noise,pulse error and other factors.In order to solve the problem,a resonant frequency measurement system based on phase-locked amplifier is designed,and the detection circuit converts the measurement of alternating vibration signal into that of DC constant voltage.The linear relationship between DC voltage and excitation frequency is found in the resonant region and utilized to present and realize an algorithm based on scan frequency to measure the resonant frequency automatically.The density calibration ex periment is carried out at(20±0.05)℃,and the temperature compensation of the density sensor is carried out.The experimental results show that in the measurement range of density from 700 kg/m^(3)to 1000 kg/m^(3),the stability of the resonant frequency measured can reach 0.002%,the maximum density error measured by the sensor is 0.48 kg/m^(3),and the maximum comprehensive measurement error is 0.069%,which verifies the effectiveness and accuracy of the resonant frequency measurement method.

关 键 词：谐振式密度传感器 谐振频率 锁相放大 温度补偿 检测电路 

分 类 号：TP212.1[自动化与计算机技术—检测技术与自动化装置]