Research On Temperature Characteristic And Compensation Method Of Capacitance Accelerometer

In the strong seismic observation network,the pickup of the strong seismograph is a capacitive accelerometer,which has the advantages of large dynamic range,high precision and good linearity.However,due to the vast territory of China,the north and South latitudes span nearly 50 degrees,resulting in a very severe climate and temperature difference,and the temperature changes between different seasons are also remarkable.This makes capacitive accelerometer very easy to be affected by temperature in actual use.For this reason,this topic has carried on the related research regarding the capacitive acceleration sensor's temperature characteristic and the compensation method.In this paper,the system model of the capacitive accelerometer is analyzed,and the temperature characteristics of the capacitive accelerometer are discussed.It is found that the temperature of the elastic component part of the acceleration sensor is most seriously affected,which will greatly influence the output error of the system.It greatly reduces the quality of data.In order to solve this problem,first of all,it is necessary to get the change of the elastic element after heating.Therefore,the finite element method is used to simulate the elastic component part of the sensor.The finite element model of the vibration part is built through the discussion of the force and constraint conditions,and the temperature field simulation of ANSYS is used to simulate the thermal coupling.Thus the deformation cloud map of the elastic element at different temperatures is obtained.A mathematical model for the change of temperature and the displacement of the capacitor plate is obtained by using the path value of the cloud image to obtain the vertical deviation of the elastic element at different temperatures and the relationship between the capacitance plate and the elastic element.Then,in order to correct the offset of the capacitor plate caused by the temperature,the existing acceleration feedback system is analyzed,and a method of temperature compensation based on circuit feedback is proposed.Through the theoretical analysis,the relationship between the feedback current and the displacement of the capacitor plate is obtained,and the theoretical value of the feedback current at different temperatures is calculated with the mathematical model obtained.Based on this analysis,the Simulink simulation model of feedback compensation is set up,and the feasibility and effectiveness of the feedback compensation are preliminarily verified.Subsequently,a temperature feedback compensation circuit is designed according to the theoretical and simulation results.Finally,according to the design of the temperature feedback compensation circuit,the temperature drift comparison experiment of the sensor and the natural cooling experiment are carried out in the temperature control room.From the final experimental results,the sensor system with feedback compensation circuit has improved the influence of temperature,and the influence of temperature change on the system is restrained to a certain extent.