Research On Calibration Technology Of High Voltage Piezoelectric Pressure Sensor

With the progress of science and technology and the development of society,more and more military and civil production related industrial fields are involved in high pressure,such as the high-pressure synthesis of new materials,kinetic energy projects penetration,shock wave testing,blasting operations,geological drilling and so on.At present,the measurement of high pressure has become a hot spot and difficulty in scientific research at home and abroad,and more studies have been carried out accordingly.The core component of the high-pressure test is the high-pressure sensor,so the performance of the high-pressure sensor largely determines the accuracy of the high-pressure measurement system.Therefore,in the industrial and military fields,it is particularly important to calibrate high-pressure sensors.The electric pressure measurement method is the most important high-pressure measurement method at present,which widely uses a piezoelectric pressure sensor to measure,has the advantages of high-frequency response and high accuracy,and is most widely used in high-pressure tests.For the detection of low-frequency bands,static calibration is mainly adopted,but there are still some problems in static calibration.First,the range of calibration equipment is small,and it is difficult to meet the calibration requirements in a wide range of high pressure.The portability is poor,and it is difficult to meet the requirements of on-site calibration in working conditions.Second,the calibration cycle is long,the efficiency is low,the loading time is too long,leading to serious charge leakage;Third,it is difficult to calculate and analyze the measured calibration data in real-time on-site.This paper designed a piezoelectric high voltage pressure sensor calibration system,using hand pressure generator as the standard pressure source,design including charge conversion,conditioning and amplification,analog-to-digital conversion,wireless transmission,and other circuits for sensing data acquisition,and use Lab VIEW to design the upper computer software of the system.Among them,the hand-operated high-pressure generator adopts hydraulic technology with triglyceride as the working medium.The design has the advantages of small volume,compact structure,high efficiency,short load loading time,and so on,and can realize frequent reversing and braking,which is convenient to meet the requirements of on-site calibration.According to the system main control module circuit,write the corresponding control program.After many experiments,the charge amplifier designed can meet the requirements of low charge leakage rate,which can ensure that the output voltage is not too small,and the influence of zero drift of the circuit is reduced to the minimum.The upper computer software designed by Lab VIEW has the characteristics of good generality,rich interface and ease to interact with other software,etc.It realizes the rapid start of using software through voice control,real-time display of data and analysis,and one-click printing of calibration results report.The calibration experiment was carried out with the designed calibration system.Through the experimental data of the standard sensor and the sensor to be calibrated,the static characteristic parameters of the sensor to be calibrated and the equation of the working line were obtained.At the same time,it is verified that the hand-cranked high voltage pressure generator designed by this system can produce pressure up to 800 MPa,and the hardware circuit designed can keep the leakage charge of the system calibration cycle to a minimum.The measurement uncertainty of the system is studied,and the influence factors that may cause errors are fully considered.The calibration system of the piezoelectric high-pressure sensor is designed to meet the design requirements.