| In the ultra-high temperature environment,temperature and pressure measurement is of great significance for the health monitoring of the parameters of aerospace vehicles and engines.The LC temperature-pressure sensor integrated on HTCC is designed for high temperature and high pressure environments.The dual LC temperature-pressure sensor designed by our research group can work at 1100 ? and the pressure range is 70~120kPa.However,there is a nonlinear problem with the temperature and pressure signals,so the temperature and pressure can only be solved by the look-up table method;the reading coil is oxidized at high temperature,so the experiment cannot be measured repeatedly.The measurement system of the sensor depends on the network analyzer,which hinders the engineering application of the sensor.In order to improve the problem of dual LC temperature-pressure sensors,a single LC temperature-pressure sensor is designed in my thesis.The temperature and pressure are measured with the thermal characteristics of the screen-printed platinum film and the principle of pressure deformation of the capacitor cavity.The sensor measures a temperature of 1200°C and a pressure of 250 kPa.The inductor and capacitor are at both ends of the HTCC substrate.During the test,the inductor is in the room temperature region,and the capacitor is placed in the high temperature region.This method not only protects the reading coil but also reduces the interference of the change of reading coil resistance and inductor parasitic capacitance caused by high temperature on the sensor signal.Experimental results show that within a certain range,the amplitude has a linear relationship with temperature,the one has a linear relationship with pressure,the resonance frequency has a linear relationship with pressure,and the one frequency has a linear relationship with temperature.The decoupling algorithm of temperature and pressure is that the two-dimensional linear equation of both amplitude and resonance frequency with respect to temperature and pressure is obtained by plane fitting,and then through mathematical transformation,the two-dimensional linear equation of temperature and pressure with respect to resonance frequency and amplitude is solved.Using the Z axis as the pressure,fitting the equation of pressure with respect to temperature and resonance frequency,this requires designing a temperature sensor to solve the pressure signal,and designing a resistance grid LC temperature sensor,both the resonance frequency and amplitude with the temperature shows a linear relationship.In order to reduce the volume of the sensor measurement system and replace the expensive and bulky vector network analyzer,the LC sensor measurement system is designed and simplified into a single-port network.The frequency sweep source AD9910 and the main control chip STM32F103 and amplitude and phase detector AD8302 are integrated as a circuit board,and the LabVIEW host computer is designed to send the frequency sweep command and display the received data through the USB port in real time.The program has the function of saving data.The measurement system uses the OSL calibration algorithm which is written in the host computer.At present,the calibration algorithm is only for a single sensor.The measurement system measures the data of the LC temperature sensor,which compared with ones measured by the vector network analyzer.The results show that the maximum relative error of the resonance frequency is 0.61%,the average absolute error of the S11 amplitude measured at each temperature point is 2.85 dB,and there is a systematic error in the measurement system. |
PDF Full Text Request