Research On Influence Factors And Compensation Technology Of Zero Drift In Charge Amplifier

As a kind of electromechanical conversion element,piezoelectric sensor plays an increasingly important role in testing field,because of its excellent dynamic performance.The charge amplifier is an indispensable secondary instrument when it is used for measurement.The zero drift problem in use greatly limits the application of charge amplifier and piezoelectric sensor in long-term measurement in static or low frequency fields.And it has a large interference with subsequent data processing.Therefore,achieving a small zero drift of the charge amplifier is of great significance for long-term accurate measurement of the piezoelectric test system in the static or low frequency field and subsequent data processing.This topic is aimed at the zero-drift compensation of general-purpose charge amplifiers.In the research process,due to the complex composition of the charge amplifier circuit,the reference parameters of the core components and the actual parameters are different due to the environment,which brings difficulties for the zero-drift analysis.When designing the compensation scheme,there is a problem of how to combine the analysis results of the zero drift influence factor with the compensation scheme.This thesis aims to compensate for the zero drift of the charge amplifier.Firstly,the circuit structure of each component of the charge amplifier and its working principle are analyzed.The influence of each part of the circuit on the zero drift of the charge amplifier is investigated,and the influence factors of the zero drift of the charge amplifier are clarified.On this basis,the charge amplifier core circuit and its components are analyzed,and a suitable charge-conversion equivalent circuit model is established according to the relevant data.The theoretical formula of the zero-drift of the charge amplifier is deduced,and the theoretical formula is combined with the measured data to make corrections and verifications.Secondly,according to the factors affecting the zero drift of the charge amplifier,the advantages and disadvantages of the two methods of hardware compensation and software compensation are compared and analyzed.The software compensation scheme is adopted to carry out the final zero drift compensation design work.On the basis of determining the compensation design scheme,the design and fabrication of the zero-point drift compensation circuit board are completed,including schematic design,PCB drawing and programming of various functional programs,thus laying a foundation for the charge drift zero drift compensation experiment.Finally,the experimental scheme of the charge amplifier zero-point drift compensation circuit is designed,and the designed compensation circuit board is tested.The final experimental results show that the software scheme has the advantages of simple structure,small size,better real-time compensation effect,easy implementation and good economical performance compared with the hardware scheme.The designed compensation circuit board has a good compensation effect,which indirectly explains the correctness of the theoretical formula of zero drift and the correctness of the software and hardware design of the compensation circuit board.