CN-122017354-A - Low-common-mode bipolar edge-control constant-current excitation low-value resistance testing method

CN122017354ACN 122017354 ACN122017354 ACN 122017354ACN-122017354-A

Abstract

The invention relates to the technical field of electronic measurement, in particular to a low-common-mode bipolar edge control constant current excitation low-value resistance testing method. The invention comprises a low common mode bipolar edge control constant current excitation low value resistance testing device, which comprises a bipolar edge control voltage module, a constant current control module, a low common mode excitation module, a tested resistor and a sampling end module; the method comprises the steps of S1, providing a bipolar voltage source Vdac with an edge control function by a DAC voltage source of a bipolar edge control voltage module, S2, connecting the output voltage Vref of the bipolar edge control voltage module with a constant current control module, S3, connecting the excitation output low end of the constant current control module with a low common mode excitation module, S4, connecting the excitation output low end and the excitation output high end of the low common mode excitation module with a tested resistor through a test cable, and S5, connecting the induction high end and the induction low end of the test cable with a sampling end module. The invention combines the edge control technology and the constant current excitation technology to realize low-common-mode and high-precision low-value resistance measurement.

Inventors

SUN DECHONG
ZHANG ZHENGLONG
WEI ZHIQIANG

Assignees

北京航天计量测试技术研究所

Dates

Publication Date: 20260512
Application Date: 20251120

Claims (8)

1. The low common mode bipolar edge control constant current excitation low value resistance testing method is characterized by comprising a low common mode bipolar edge control constant current excitation low value resistance testing device, wherein the low common mode bipolar edge control constant current excitation low value resistance testing device comprises: the output end of the bipolar edge control voltage module is connected with the input end of the constant current control module; The output end of the constant current control module is connected with the input end of the low common mode excitation module; the low common mode excitation module is connected with the measured resistor and the sampling end module; The low common mode bipolar edge control constant current excitation low value resistance testing method comprises the following steps: S1, a DAC voltage source of the bipolar edge control voltage module provides a bipolar voltage source Vdac with an edge control function; s2, the output voltage Vref of the bipolar edge control voltage module is connected with the constant current control module; s3, the excitation output low end of the constant current control module is connected with the low common mode excitation module; s4, the low excitation output end and the high excitation output end of the low common mode excitation module are connected with the resistor to be tested through a test cable; S5, the induction high end and the induction low end of the test cable are connected with the sampling end module.
2. The method for testing the low-value resistance of the low-common-mode bipolar edge control constant current excitation according to claim 1, wherein the bipolar edge control voltage module comprises a voltage source VP and a voltage follower circuit U1, the voltage source VP is connected with a non-inverting input end of the voltage follower circuit U1, and an output end of the voltage follower circuit U1 is connected with an inverting input end of the voltage follower circuit U1 and the constant current control module.
3. The method for testing the low-common-mode bipolar edge-controlled constant-current excitation low-value resistor according to claim 2, wherein the constant-current control module comprises a differential amplification circuit, a power amplification output circuit, a voltage follower circuit and a standard resistor Rm, wherein the differential amplification circuit comprises an operational amplifier U2 and a resistor R1, the in-phase input end of the operational amplifier U2 is connected with the output end of the voltage follower circuit U1, the output end of the operational amplifier U2 is connected with one end of the resistor R1, the power amplification output circuit comprises a power amplifier U3, a resistor R2, a resistor R3 and a capacitor Cb1, the other end of the resistor R1 is connected with the in-phase input end of the power amplifier U3, the inverting input end of the power amplifier U3 is respectively connected with one end of the resistor R2, the other end of the resistor R2 is connected with one end of the capacitor Cb1, the other end of the capacitor Cb1 is connected with the output end of the power amplifier U3, the output end of the power amplifier U3 is connected with a pin p of the resistor R3, one end of the output end of the power amplifier U3 is connected with one end of the resistor R4, and the other end of the resistor R4 is connected with the standard resistor R4, and the other end of the resistor R4 is connected with the in-phase end of the resistor R4 is connected with the operational amplifier R4.
4. The method for testing the low-common-mode bipolar edge-controlled constant-current excitation low-value resistor according to claim 3, wherein the integrating circuit comprises an operational amplifier U5, a resistor R6 and a capacitor C1, the inverting input end of the operational amplifier U5 is connected with one end of the resistor R5 and one end of the capacitor C1, the other end of the capacitor C1 is connected with the output end of the operational amplifier U5 and one end of the resistor R6, the power amplifier output circuit comprises a power amplifier U6, a resistor R7, a resistor R8 and a capacitor Cb2, the other end of the resistor R6 is connected with the non-inverting input end of the power amplifier U6, the inverting input end of the power amplifier U6 is connected with one end of the resistor R7, the other end of the resistor R7 is respectively connected with one end of the capacitor Cb2, one end of the resistor R8 and the output end of the power amplifier U6, and the other end of the capacitor Cb2 is connected with the Comp pin of the power amplifier U6.
5. The method for testing the low-common-mode bipolar edge-controlled constant current excitation low-value resistor according to claim 4, wherein the low-common-mode bipolar edge-controlled constant current excitation low-value resistor testing device further comprises the following steps that the other end of the resistor R8 outputs an excitation output high end and is connected with one end of a four-wire test cable equivalent resistor Rw3, the other end of the resistor R5 outputs an excitation output low end and is connected with one end of a four-wire test cable equivalent resistor Rw1, the other end of the four-wire test cable equivalent resistor Rw3 and the other end of the four-wire test cable equivalent resistor Rw1 are respectively connected with two ends of a tested resistor RX, the two ends of the tested resistor RX are respectively connected with one end of a four-wire test cable equivalent resistor Rw2 and one end of a four-wire test cable equivalent resistor Rw4, and the other end of the four-wire test cable equivalent resistor Rw4 respectively outputs an induction high end and an induction low end and is connected with the sampling end module.
6. The method for testing the low-value resistance of the low-common-mode bipolar edge-control constant-current excitation device according to claim 1, wherein the sampling end module comprises a filter circuit and an analog voltage signal acquisition unit, and the analog voltage signal acquisition unit comprises an ADC unit.
7. The method for testing the low-value resistance of the low-common-mode bipolar edge-control constant-current excitation of claim 6, wherein the step S2 of connecting the bipolar edge-control voltage module output voltage Vref to the constant-current control module comprises the following steps: S21, the voltage Vref enters the operational amplifier U2, the loop of the operational amplifier U2 is closed, and feedback loop resistors with equal resistance and consistent parameters are integrated in the operational amplifier U2, namely ; The gain of the negative feedback loop of the operational amplifier U2 is The method comprises the following steps of: wherein V3 is the voltage of the Sense pin of operational amplifier U2; The gain of the positive feedback loop of the operational amplifier U2 is The method comprises the following steps of: ; As the operational amplifier U2 is short in deficiency, it can be seen that I.e. Wherein V5 is the voltage of the Ref pin of the operational amplifier U2; s22, the power amplifier output circuit provides measurement excitation current, the power amplifier U3 uses a voltage follower, and an input and output voltage formula is adopted ; S23, an input/output voltage formula of the voltage follower circuit U1 ; S24, current flowing through the standard resistor Rm Is that The above formula can be used to obtain: 。
8. The method for testing the low-value resistor with the low-common-mode bipolar edge control constant current excitation according to claim 7, wherein the standard resistor Rm is a standard resistor with accuracy of ten-thousandth and temperature stability within 5 PPM.

Description

Low-common-mode bipolar edge-control constant-current excitation low-value resistance testing method Technical Field The invention relates to the technical field of electronic measurement, in particular to a low-common-mode bipolar edge-control constant-current excitation low-value resistance testing method. Background The importance and difficulty of low-value resistance measurement are that in power equipment, the contact resistance of busbar and breaker contacts is usually in milliohm or even microohm level, the resistance directly influences the safe and stable operation of the equipment, and accurate measurement is helpful for evaluating the performance of the equipment and predicting faults. In the field of new energy batteries, the equivalent series resistance inside the battery is related to the charge and discharge efficiency and the service life of the battery, and key data can be provided for battery research and development and quality control by accurately measuring. However, the low-value resistor has small resistance, is extremely easy to be interfered by additional resistors such as lead resistors, contact resistors and the like, and causes larger measurement errors. Meanwhile, factors such as external electromagnetic interference and environmental temperature change can also have significant influence on the measurement result, so that accurate measurement is very challenging. The conventional measuring method has the limitations that the common measuring method such as volt-ampere method calculates the resistance value by measuring the current flowing through the resistor and the voltage at two ends of the resistor, and the principle is simple, but for low-value resistor, the voltage drop at two ends of the resistor is weak, so that the resistor is extremely easy to be influenced by the noise of a measuring instrument and the external electromagnetic interference, and the measuring precision is difficult to ensure. The bridge method improves the measurement accuracy to a certain extent, such as a Wheatstone bridge, a Kerr Wen Dianqiao and the like, can effectively eliminate the influence of lead resistance and contact resistance, but in the measurement process, the balance adjustment of the bridge is complicated, the measurement speed is low, and the requirement of quick measurement is difficult to meet. In addition, the traditional methods have limited capability in terms of common mode interference suppression, and under a complex electromagnetic environment, the common mode interference can be converted into differential mode interference, so that measurement accuracy is seriously affected. The constant current excitation technology is applied to low-value resistance measurement in order to improve measurement accuracy. By applying a constant current to the measured resistor, measuring the voltage at both ends of the resistor and calculating the resistance value by using ohm's law, the influence of power supply fluctuation on the measurement result can be reduced. However, the conventional constant-current excitation source has the problem of high common-mode voltage, and the common-mode voltage can generate common-mode current in a measurement loop so as to introduce measurement errors. Moreover, the conventional unipolar constant current excitation mode cannot effectively eliminate the influence of nonlinear factors such as parasitic capacitance, inductance and the like possibly existing in the measured resistor, so that deviation exists in a measurement result, and the influence is particularly obvious when measuring a low-value resistor with high-frequency characteristics. The conventional bipolar constant current excitation mode changes the polarity of the output current by switching the direction of the current flowing through the resistor to be tested through a relay, which causes electromagnetic interference and signal overshoot to be generated at the switching moment and influences the test result. The development and demand of edge control technology, namely edge control technology, is gradually applied in the fields of signal processing and measurement. By precisely controlling the rising edge and the falling edge of the excitation signal, electromagnetic interference and signal overshoot generated at the switching moment can be eliminated, precise control over the measurement process is realized, and the response speed and resolution of the measurement system are improved. However, the application of the existing edge control technology in low-value resistance measurement is not mature enough, and a complete solution which can effectively inhibit common-mode interference and overcome the difficulty of low-value resistance measurement is not formed. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, the invention aims to provide a low-common-mode bipolar edge control constant current