The Study And Design Of The Measurement Circuit For The Piezoelectric Accelerometer

In the modern industry and automatic production the measurement of non-electric physical quantity and the control technology involve a large volume of questions about dynamic measurement and test. The dynamic measurement and test mean to determine the instantaneous value of a variable and its variations with time, which is a continuous measurement process to determine the value of a measurand as a variable. Dynamic signals are regarded as characteristics of the process, has studied the systematic dynamic characteristic problem of testing. And the accurate measurement of the vibration and strike in testing dynamically seems especially important. The most important problem of the measurement of the vibration and strike is the sensor. For the acquisition of signal, the most common sensor one uses is the piezoelectric accelerometer. All over the world, the standard acceleration sensor of the as amount value transmit standard high frequency and intermediate frequency shake is the piezoelectric accelerometer. Therefore, the piezoelectric accelerometer with fine quality all has distinctive quality in such aspects as precision, stability for a long time. Piezoelectric accelerometer can be regarded as the with high impedance component that can produce charge. But this charge amount is very small, can't carry on measurement with the general measurement circuit, because the input impedance of general measurement circuit is always light, the error of measuring would be lead into measuring for the charge of the piezoelectricity slice will be leak through the light input resistance, influence the measurement result. If the piezoelectric accelerometer has not been cooperated and used together with its related measurement circuit, then the wide application of the piezoelectric accelerometer would receive very great restriction. So, the study of the measurement circuit and the realization of the hardware related to it seem very important. The measurement circuit of the most frequent used for piezoelectric accelerometer is the charge amplifier at present, it can get a kind of voltage output that is proportional to the input charge. One of its characteristics is to make the sensitivity of the sensor have nothing to do with thelength of the cable, the cable can reach several kilometers, but there is only a small sensor near the target been examined. This is very convenient for user. But the present charge amplifier circuit is more complicated, price of the machine is higher, the cost performance is not very ideal, all these factors influence the mass use of the sensor of acceleration of piezoelectricity seriously, so develops a kind of charge amplifier which has higher cost performance and more utility is very necessary. Based on the above-mentioned situations, this text has done deep research to the measurement circuit of the sensor, analyze different measurement circuit characteristics, and put forward an assume that can achieve realize charge change imagination of circuit using a kind of integrated chip replace a large number of leave component, and verify the feasibility and dependability of the designed through the experiment. Make careful theory analyze to interfering signal that exist, adopt relevant way solve, and contrast with standard charge amplifier finally. The experimental result indicates that it is feasible to originally design.