The Development Of Measurement Circuit For The Piezoelectric Accelerometer

Piezoelectric accelerometer is at the very core of the measurement in the vibration and strike, and it is very important in modern industry and automatic production. Especially in precision, long-time stability it has very fine quality. Piezoelectric accelerometer can be regarded as the component that can produce charge with the high impedance. But this charge amount is very small, and the input impedance of general measurement circuit is always small, the charge of the piezoelectricity slice would be leaked easily through this measurement circuit, and it can bring in inaccuracy of the measurement. So the piezoelectric accelerometer has been matched with its related measurement circuit, or else the wide application has been greatly restricted.At present, most popular measurement circuit used for piezoelectric accelerometer is charge amplifier. It can get a kind of voltage output which is proportional to the input charge. One of its characteristics is to make the sensitivity of the sensor have nothing to do with the length of the cable. A design of charge amplifier which used integrated chip replace a large number of leave components has been developed in the paper. It contains six parts of charge convert, normalization magnify, high and low pass filter, output amplifier stage, stabilized voltage power supply and overload indicator. In order to solve the problem of error and interfere to the system by manual regulation, a programme-controlled scheme in sensitivity throw-over of charge convert and gain throw-over of output amplifier has been proposed in this paper. The principle analysis of error and undesired signal has been done at great length, and relevant way to solve it has been adopted in the paper, too. Finally the system is contrasted with the standard charge amplifier, the experimental result indicated that it is feasible to original design.Main works of the author:(1) Has developed a design of charge amplifier which using a kind of integrated chip replace a large number of leave components, though all the realized proposal of measurement circuit for the piezoelectric accelerometer;(2) Has made the circuit board;(3) Has proposed a programme-controlled scheme in the sensitivity throw-over of charge convert and gain throw-over of output amplifier;(4) Has done the experiment, give the experimental result;(5) Has done the error analysis based on the experimental result and the principle of the charge amplifier.