Research On High-precision Measurement Circuit Of Differential Resonant High Voltage Senso

Resonance sensor has many advantages such as low power consumption,high signal to noise ratio of output signal and strong anti-interference,which is a very important research direction in sensor technology.However,the traditional resonant sensor measurement circuit is more and more difficult to meet the measurement needs of the sensor because of the low accuracy and real-time.Aiming at the requirement of technical index,cost and volume of differential resonance high voltage sensor,this paper proposes a frequency measurement scheme combining equal precision frequency measurement method and quantitative delay method by analyzing the advantages and disadvantages of the current mainstream frequency measurement scheme.This scheme combines the advantages of two methods of measurement,on the one hand,such as precision frequency measuring method which can realize the actual gate and synchronization of the frequency signal under test as well as the entire range within the scope of the measuring precision,but is unable to overcome the reference clock error of plus or minus 1 word count problem,on the other hand,quantitative Shi Yan Fa is especially suitable for for less than one clock cycle time interval measurement,But it is not suitable for long time measurement.By combining the two,high precision and high resolution measurement of frequency signal can be achieved.The hardware implementation of this paper is based on Xilinx FPGA chip.One of the key points is to use CARRY 4 resources to build the delay chain circuit.Due to the influence of manufacturing process,voltage,temperature and other factors,the delay value of the delay unit fluctuates to some extent,leading to the inaccuracy of the measurement results.Therefore,this paper designs a calibration circuit based on code density principle,which can be calibrated regularly to improve the accuracy of the delay chain measurement.The measuring circuit adopts double channel design,which can simultaneously meet the measurement requirements of two differential frequency quantities of the sensor.The measurement results are synchronized by the synchronous circuit to ensure the synchronization of the two channels.Finally,a test platform was built to test the performance of the measurement circuit.The test results show that the maximum measurement error of the two frequency measurement channels within the range is not more than 0.018 Hz,which can better meet the working requirements of the differential resonant voltage sensor at the present stage and has certain engineering significance.