Calibration method and device of capacitance measurement circuit
A technology of capacitance measurement and calibration method, applied in measurement devices, measurement of electrical variables, measurement of resistance/reactance/impedance, etc., can solve the problem of large influence of environmental factors, and achieve the effect of improving measurement accuracy and eliminating random errors in capacitance measurement.
Active Publication Date: 2011-06-15
BEIJING AEROSPACE MEASUREMENT & CONTROL TECH
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That is to say, the calibration method in the prior art is greatly affected by environmental factors
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[0037] The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.
[0038] The following will take the distributed capacitance test of the cable by the capacitive reactance method as an example for specific description.
[0039] When measuring the capacitance of the cable in small ranges of 100pF to 1000PF and 1nF to 20nF, it was found that the random measurement error is relatively large when the capacitance of the small range has been calibrated and measured again afterwards. Analyzing the reason, it is mainly due to the influence of temperature, humidity and other environmental parameters, the random measurement error is relatively large, and the small-range capacitance gear that has been calibrated, the measured value of the measured capacitance changes greatly, and the measurement accuracy cannot be guaranteed. Therefore, adopting a dynamic calibration measurement method can greatly improve the a...
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The invention discloses a calibration method of a capacitance measurement circuit, which is suitable for calibrating the capacitance measurement circuit by utilizing a capacitance reactance method. The calibration method comprises the following steps of: A. recording AD (Analog to Digital) acquisition values corresponding to a plurality of known capacitors, respectively solving a difference valuebetween the AD acquisition value of each known capacitor and the AD acquisition value of a reference capacitor; B. constructing an input-output characteristic equation of the capacitance measurement circuit by each known capacitance value and the corresponding difference value; C. obtaining the AD acquisition values of a capacitor to be measured and the reference capacitor in an actual environment, and introducing the difference value of the AD acquisition values to the input-output characteristic equation to obtain the value of the capacitor to be measured. By utilizing the method disclosed by the invention, the random capacitance measurement error brought by temperature and humidity variations of the environment can be effectively reduced. Correspondingly, the invention also discloses acalibration device of the capacitance measurement circuit, which comprises an input-output characteristic equation construction module and a capacitance actual measurement module.
Description
technical field [0001] The invention belongs to the technical field of test and measurement, in particular to a calibration method and device for a capacitance measurement circuit. Background technique [0002] The capacitance test method generally adopts the pulse width modulation method and the capacitive reactance method to measure. The disadvantage of the pulse width modulation method for measuring capacitance is that the circuit itself cannot be automatically zeroed, and manual zeroing is required before each measurement, thus prolonging the measurement time. The capacitive reactance measurement method can realize the automatic zero adjustment of the capacitance and shorten the measurement time. [0003] The principle of capacitive reactance method to measure capacitance is to use sine wave signal to change the measured capacitance Cx into capacitive reactance Xc, then perform C / U conversion (capacitance voltage conversion), convert Xc into AC signal voltage, and then ...
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Inventor 苏建军蔄元臣朱红陈斐郇黎明
Owner BEIJING AEROSPACE MEASUREMENT & CONTROL TECH