CN103235189B - A kind of micro-resistance high-precision measuring method based on double-current voltage ratio method and realize the measuring system of the method - Google Patents

Abstract

A high-precision measurement method for micro-resistance based on a double-current-voltage ratio method and a measurement system for realizing the method, it relates to a high-precision measurement method and system for resistance, and specifically relates to a detection method and system for micro-resistance. In order to solve the problem of power supply accuracy and the influence of DC interference superimposed on the measured micro-voltage signal on the measurement accuracy in the existing micro-resistance measurement technology, the measurement system of the present invention includes a measured resistance, a standard resistance, an adjustable current limiting Resistors, controllable power supplies, filter amplifiers, A/D converters, single-chip microcomputer systems, displays and operating keyboards, firstly, use the voltage ratio method to eliminate the influence of the power supply on the measurement accuracy, and secondly, use the double current method to eliminate the resistance value of the measured resistor The DC interference voltage above, the invention is applicable to the technical field of micro-resistance measurement.

Description

A high-precision measurement method for micro-resistance based on the dual current-voltage ratio method and a measurement system for realizing the method

technical field

The invention relates to a high-precision measurement method and system for resistance, in particular to a detection method and system for tiny resistance.

Background technique

In the field of electrical engineering, the problem of micro-resistance measurement is often encountered, such as the measurement of the resistivity of conductor materials, the measurement of DC resistance per unit length of conductors, etc. Since these microresistances are often in the order of tens of μΩ to tens of mΩ, it is difficult to measure them. At present, the micro-resistance measuring instruments provided on the market are generally DC double-arm bridges and digital micro-ohmmeters. The DC double-arm bridge needs to be balanced and adjusted, and the degree of measurement automation is low and easily affected by changes in adjustable components and human factors; digital micro-ohmmeters generally use constant current source and high-precision digital voltage measurement technology, and the degree of automation, measurement speed and measurement The accuracy is high, and there is a tendency to gradually replace the DC double-arm bridge. In the development process of digital micro-ohmmeter, the main difficulties lie in the production of high-precision constant current source, data acquisition of high-precision micro-voltage signal and anti-interference technology. Among them, it is difficult to make a high-precision constant current source, which has always affected the accuracy level of micro-resistance measurement; high-precision micro-voltage data acquisition can be solved by using high-performance operational amplifiers and high-level A/D converters available on the market; interference generally includes electric field interference, Magnetic field interference and DC interference, electromagnetic field interference can be effectively suppressed by shielding and filtering methods, DC interference is directly superimposed on the measured micro-voltage signal, which has a very large impact on the precise measurement of micro-resistance, and it is difficult to suppress.

In the basic principle of voltage ratio method measurement, AC interference can be effectively suppressed by techniques such as shielding and filtering, and the influence of DC interference on measurement is ignored. The thermoelectric potential of the measurement circuit, the imbalance of the amplifier circuit, and the temperature drift form DC interference, which is superimposed on the measured voltage drop. Since the measured voltage drop is weak, the superimposed DC interference will produce a very large measurement error, and the existing measurement methods are not cannot be eliminated. Through actual measurement, it is found that, in the long run, this kind of DC interference will produce certain fluctuations due to factors such as temperature changes.

Contents of the invention

The purpose of the present invention is to solve the problem of power supply accuracy and the influence of DC interference superimposed on the measured micro-voltage signal on the measurement accuracy in the existing micro-resistance measurement technology. The present invention proposes a dual-current-voltage ratio method. A micro-resistance high-precision measurement method and a measurement system for realizing the method.

A high-precision measurement method for micro-resistance based on the dual-current-voltage ratio method. The specific process is as follows. First, connect the measured resistance, fixed-value resistance and adjustable current-limiting resistance in series on the power output side of the controllable DC power supply to form a series closed loop. , the output voltage of the controllable DC power supply is E, the resistance value of the measured resistance is R _X , the resistance value of the fixed-value resistance is R ₀ , the resistance value of the adjustable current-limiting resistance is R ₁ , and a four-wire resistance measurement is used The method measures and obtains the measured voltage U ₁ at both ends of the fixed resistance, the measured voltage U ₂ at both ends of the measured resistance and the current I of the series closed loop, and calculates the resistance value R _X of the measured resistance,

Secondly, the DC interference voltage on the resistance value R _X of the measured resistance is eliminated by the double current method, and the resistance value R _X of the measured resistance after the interference is eliminated is obtained.

This embodiment adopts the voltage ratio method to eliminate the influence of the output voltage _E of the controllable DC power supply on the measurement _accuracy of the measured resistance. The flow resistance is used to control the magnitude of the measured current I.

The calculation obtains the resistance value of the measured resistance, and its specific process is, according to the formula Calculate and obtain the resistance value R _X of the resistor under test.

said formula R ₀ is according to the formula $I=\frac{\mathrm{E.}}{R_1+R_0+R_x}=\frac{u_1}{R_0}=\frac{u_2}{R_x}$ obtained by derivation.

The direct current interference voltage on the resistance value R _X of the measured resistance is eliminated by the double current method, and the resistance value R _X of the measured resistance after the interference is eliminated is obtained. The specific process is as follows:

Set the output voltages of the controllable DC power supply to E ₁ and E ₂ respectively, and E ₁ is greater than E ₂ ,

When the output voltage of the controllable DC power supply is E ₁ , the current corresponding to the series closed loop is I ₁ , measure the voltage at both ends of the fixed resistor to obtain the measured voltage U ₁₁ , measure the voltage at both ends of the measured resistance to obtain the measured voltage U ₂₁ ,

When the output voltage of the controllable DC power supply is E ₂ , the current corresponding to the series closed loop is I ₂ , measure the voltage across the fixed resistor to obtain the measured voltage U ₁₂ , measure the voltage across the measured resistance to obtain the measured voltage U ₂₂ , according to formula Calculate and obtain the resistance value R _X of the measured resistance after the interference is eliminated.

The principle of eliminating the DC interference voltage on the resistance value R _X of the measured resistance through the double current method described in this embodiment, and obtaining the resistance value R _X of the measured resistance after the interference is eliminated is:

When the output voltage of the controllable DC power supply is E ₁ , the current corresponding to the series closed loop is I ₁ , the voltage at both ends of the fixed resistance is measured to obtain the measured voltage U ₁₁ , and the voltage at both ends of the measured resistance is measured to obtain the measured voltage U ₂₁ ,

Then there is, U ₁₁ =U ₀₁ +E _s1 (3),

U ₂₁ =U _x1 +E _s2 (4),

Among them, U ₀₁ is the actual voltage at both ends of the fixed resistance, U _X1 is the actual voltage at both ends of the measured resistance, E _s1 is the DC interference voltage on the measurement voltage U ₁₁ , and E _s2 is the DC interference voltage on the measurement voltage U ₂₁ ;

When the output voltage of the controllable DC power supply is E ₂ , the current corresponding to the series closed loop is I ₂ , measure the voltage across the fixed value resistor to obtain the measured voltage U ₁₂ , measure the voltage across the measured resistance 1 to obtain the measured voltage U ₂₂ ,

Then there is, U ₁₂ =U ₀₂ +E _s3 (5),

U ₂₂ =U _x2 +E _s4 (6),

Among them, U ₀₂ is the actual voltage at both ends of the fixed resistance, U _X2 is the actual voltage at both ends of the measured resistance, E _s3 is the DC interference voltage on the measurement voltage U ₁₂ , and E _s4 is the DC interference voltage on the measurement voltage U ₂₂ ;

Among them, E _s1 =E _s3 , E _s2 =E _s4 ;

Calculated by formulas (3), (4), (5) and (6), U ₁₁ -U ₁₂ =U ₀₁ -U ₀₂ =R ₀ (I ₁ -I ₂ ) (7),

U ₂₁ -U ₂₂ =U _X1 -U _X2 =R _x (I ₁ -I ₂ ) (8),

After finishing formula (7) and formula (8), we get, $R_x=R_0\frac{u_{01}-u_{02}}{u_{x1}-u_{x2}}=R_0\frac{u_{\mathrm{twenty\; one}}-u_{\mathrm{twenty\; two}}}{u_{11}-u_{12}}.$

from the formula It can be concluded that the double current method is used to eliminate the influence of DC interference voltage on the measurement accuracy.

The pulse widths of the currents I ₁ and I ₂ are the same, both being 1 second.

The magnitude of the current I ₁ is 1A.

The magnitude of the current I ₂ is 5A.

The currents I ₁ and I ₂ are output continuously and alternately, forming a periodic current with a period of 2 seconds.

Realize a measurement system based on the dual-current-voltage ratio method for high-precision measurement of micro-resistance, the measurement system includes a measured resistance, a fixed-value resistance, an adjustable current-limiting resistance, a controllable power supply, a filter amplifier, an A/D Converter, single-chip microcomputer system, display and operation keyboard, one end of the measured resistance is grounded, the other end of the measured resistance is connected to one end of the fixed-value resistor, and the other end of the fixed-value resistor is connected to one end of the adjustable current-limiting resistor , the other end of the adjustable current-limiting resistor is connected to the positive output terminal of the controllable power supply, the negative input terminal of the controllable power supply is connected to the voltage control signal output terminal of the single-chip microcomputer system, and the four-wire resistance measurement method is used to collect the value of the fixed value resistor terminal voltage signal, and send the voltage signal to the filter amplifier; use the four-wire resistance measurement method to collect the terminal voltage signal of the measured resistance, and send the voltage signal to the filter amplifier; the signal output terminal of the filter amplifier and A/D conversion The analog signal input end of the device is connected, the digital signal output end of the A/D converter is connected with the acquisition signal input end of the single-chip microcomputer system, and the display signal output end of the single-chip microcomputer system is connected with the signal input end of the display. The signal output terminal of the operation keyboard is connected with the signal input terminal of the single-chip microcomputer system.

The beneficial effects brought by the high-precision measurement method of micro-resistance based on the dual-current-voltage ratio method and the measurement system for realizing the method described in the present invention are: the voltage ratio method is used to eliminate the influence of the power supply on the measurement accuracy, and the dual-current method is used Eliminate the impact of DC interference on the measurement accuracy, it has the characteristics of strong anti-interference ability and high measurement accuracy, its anti-interference ability has increased by more than 30%, and the measurement accuracy can reach 0.1 micro-ohm level.

Description of drawings

FIG. 1 is an equivalent circuit diagram of a method for measuring micro-resistance with high precision based on the dual current-voltage ratio method described in the first embodiment.

FIG. 2 is an equivalent circuit diagram of the high-precision micro-resistance measurement method based on the dual current-voltage ratio method when the output voltage _of the controllable DC power supply is E1 in the third specific embodiment.

FIG. 3 is a functional block diagram of a measurement system for implementing a high-precision measurement method for micro-resistance based on the dual-current-voltage ratio method described in the first embodiment.

Detailed ways

Specific Embodiment 1: A high-precision measurement method for micro-resistors based on the dual current-voltage ratio method described in this embodiment, the specific process is as follows, first, the measured resistance 1, the fixed-value resistance 2 and the adjustable current-limiting resistance 3 connected in series to the power output side of the controllable DC power supply to form a series closed loop, the output voltage of the controllable DC power supply is E, the resistance value of the measured resistance 1 is R _X , and the resistance value of the fixed value resistance 2 is R ₀ , which can be Adjust the resistance value of the current-limiting resistor 3 to R ₁ , use the four-wire resistance measurement method to measure and obtain the measured voltage U ₁ at both ends of the fixed value resistor 2, the measured voltage U ₂ at both ends of the measured resistor 1 and the current I of the series closed loop, and calculate Obtain the resistance value R _X of the measured resistance 1,

Secondly, the DC interference voltage on the resistance value R _X of the measured resistance 1 is eliminated by the double current method, and the resistance value R _X of the measured resistance 1 after the interference is eliminated is obtained.

This embodiment adopts the voltage ratio method to eliminate the influence of the output voltage E of the controllable DC power supply on the measurement accuracy of the measured resistance 1, and the resistance value R _X of the fixed value resistance 2 is known, which is used to calibrate the resistance R _X of the measured resistance 1, The adjustable current limiting resistor 3 is used to control the magnitude of the measured current I.

Specific embodiment 2: Referring to Fig. 1 to illustrate this embodiment, the difference between this embodiment and a kind of micro-resistance high-precision measurement method based on the dual current-voltage ratio method described in the specific embodiment 1 is that the measured The resistance value of resistor 1, the specific process is, according to the formula The resistance value R _X of the measured resistor 1 is obtained by calculation.

said formula R ₀ is according to the formula $I=\frac{\mathrm{E.}}{R_1+R_0+R_x}=\frac{u_1}{R_0}=\frac{u_2}{R_x};$ obtained by derivation.

Specific embodiment three: Referring to FIG. 2 to illustrate this embodiment, the difference between this embodiment and the high-precision measurement method for micro-resistance based on the dual current-voltage ratio method described in the specific embodiment one is that the described dual-current method Eliminate the DC interference voltage on the resistance value R _X of the measured resistance 1, and obtain the resistance value R _X of the measured resistance 1 after the interference is eliminated. The specific process is as follows:

Set the output voltages of the controllable DC power supply to E ₁ and E ₂ respectively, and E ₁ is greater than E ₂ ,

When the output voltage of the controllable DC power supply is E ₁ , the current corresponding to the series closed loop is I ₁ , measure the voltage across the fixed resistor 2 to obtain the measured voltage U ₁₁ , measure the voltage across the measured resistor 1 to obtain the measured voltage U ₂₁ ,

When the output voltage of the controllable DC power supply is E ₂ , the current corresponding to the series closed loop is I ₂ , measure the voltage across the fixed resistor 2 to obtain the measured voltage U ₁₂ , measure the voltage across the measured resistor 1 to obtain the measured voltage U ₂₂ , according to the formula Calculate and obtain the resistance value R _X of the measured resistance 1 after the interference is eliminated.

The principle of eliminating the DC interference voltage on the resistance value R _X of the measured resistance 1 by the double current method described in this embodiment and obtaining the resistance value R _X of the measured resistance 1 after the interference is eliminated is as follows:

When the output voltage of the controllable DC power supply is E ₁ , the current corresponding to the series closed loop is I ₁ , the voltage across the fixed resistor 2 is measured to obtain the measured voltage U ₁₁ , and the voltage across the measured resistor 1 is measured to obtain the measured voltage U ₂₁ ,

Then there is, U ₁₁ =U ₀₁ +E _s1 (3),

U ₂₁ =U _x1 +E _s2 (4),

Among them, U ₀₁ is the actual voltage across the fixed resistance 2, U _X1 is the actual voltage across the measured resistance 1, E _s1 is the DC interference voltage on the measured voltage U ₁₁ , E _s2 is the DC interference on the measured voltage U ₂₁ Voltage;

When the output voltage of the controllable DC power supply is E ₂ , the current corresponding to the series closed loop is I ₂ , measure the voltage across the fixed resistor 2 to obtain the measured voltage U ₁₂ , measure the voltage across the measured resistor 1 to obtain the measured voltage U ₂₂ ,

Then there is, U ₁₂ =U ₀₂ +E _s3 (5),

U ₂₂ =U _x2 +E _s4 (6),

Among them, U ₀₂ is the actual voltage across the fixed resistance 2, U _X2 is the actual voltage across the measured resistance 2, E _s3 is the DC interference voltage on the measured voltage U ₁₂ , and E _s4 is the DC interference on the measured voltage U ₂₂ Voltage;

Among them, E _s1 =E _s3 , E _s2 =E _s4 ;

Calculated by formulas (3), (4), (5) and (6), U ₁₁ -U ₁₂ =U ₀₁ -U ₀₂ =R ₀ (I ₁ -I ₂ ) (7),

U ₂₁ -U ₂₂ =U _X1 -U _X2 =R _x (I ₁ -I ₂ ) (8),

After finishing formula (7) and formula (8), we get, $R_x=R_0\frac{u_{01}-u_{02}}{u_{x1}-u_{x2}}=R_0\frac{u_{\mathrm{twenty\; one}}-u_{\mathrm{twenty\; two}}}{u_{11}-u_{12}}.$

from the formula It can be concluded that the double current method is used to eliminate the influence of DC interference voltage on the measurement accuracy.

Specific embodiment four: refer to Fig. 2 and illustrate this embodiment, the difference between this embodiment and a kind of micro-resistor high-precision measurement method based on the dual current-voltage ratio method described in the specific embodiment three is that the described current _I1 and The pulse width of I ₂ is the same, both are 1 second.

Specific embodiment five: refer to Fig. 2 and illustrate this embodiment, the difference between this embodiment and a kind of micro-resistor high-precision measurement method based on the dual current-voltage ratio method described in the specific embodiment three is that the current I ₁ The amplitude is 1A.

Specific embodiment six: refer to Fig. 2 to illustrate this embodiment, the difference between this embodiment and a kind of micro-resistor high-precision measurement method based on the dual current-voltage ratio method described in the specific embodiment three is that the current I ₂ The amplitude is 5A.

Specific embodiment seven: refer to Fig. 2 to illustrate this embodiment, the difference between this embodiment and a kind of micro-resistor high-precision measurement method based on the dual current-voltage ratio method described in the specific embodiment three is that the described current _I1 and I ₂ is continuously output alternately, forming a periodic current with a period of 2 seconds.

Embodiment 8: Refer to FIG. 3 to illustrate this embodiment. This embodiment implements the measurement system of a micro-resistance high-precision measurement method based on the dual current-voltage ratio method described in Embodiment 1. The measurement system includes Measuring resistance 1, fixed value resistance 2, adjustable current limiting resistance 3, controllable power supply 9, filter amplifier 4, A/D converter 5, single-chip microcomputer system 6, display 7 and operation keyboard 8, the measured resistance 1 One end is grounded, the other end of the measured resistance 1 is connected to one end of the fixed value resistor 2, the other end of the fixed value resistor 2 is connected to one end of the adjustable current limiting resistor 3, the other end of the adjustable current limiting resistor 3 is connected to the controllable The positive power output terminal of the power supply 9 is connected, the negative power input terminal of the controllable power supply 9 is connected with the voltage control signal output terminal of the single-chip microcomputer system 6, and the terminal voltage signal of the fixed value resistor 2 is collected by a four-wire resistance measurement method, and the voltage The signal is sent to the filter amplifier 4; the terminal voltage signal of the measured resistance 1 is collected by the four-wire resistance measurement method, and the voltage signal is sent to the filter amplifier 4; the signal output terminal of the filter amplifier 4 is connected to the analog of the A/D converter 5 The signal input end is connected, and the digital signal output end of described A/D converter 5 is connected with the acquisition signal input end of single-chip microcomputer system 6, and the display signal output end of described single-chip microcomputer system 6 is connected with the signal input end of display 7, so The signal output end of the operation keyboard 8 described above is connected with the signal input end of the single-chip microcomputer system 6.

Claims (3)

1. the micro-resistance high-precision measuring method based on double-current voltage ratio method, it is characterized in that, detailed process is as follows, first, power supply outgoing side measured resistance (1), fixed value resistance (2) and adjustable current-limiting resistance (3) being connected on controllable direct current power supply forms series connection closed-loop path, the output voltage of described controllable direct current power supply is E, and the resistance of measured resistance (1) is R _x, the resistance of fixed value resistance (2) is R ₀, the resistance of adjustable current-limiting resistance (3) is R ₁, adopt four-wire ohm measuring method to measure the measuring voltage U obtaining fixed value resistance (2) two ends ₁, measured resistance (1) two ends measuring voltage U ₂electric current I with series connection closed-loop path, calculates the resistance R of measured resistance (1) _x,

Secondly, the resistance R of measured resistance (1) is eliminated by double current method _xon interference voltages, obtain and eliminate the resistance R of measured resistance (1) after interference _{x '};

The described resistance R being eliminated measured resistance (1) by double current method _xon interference voltages, obtain and eliminate the resistance R of measured resistance (1) after interference _{x '}, its detailed process is as follows:

The output voltage arranging controllable direct current power supply is respectively E ₁and E ₂, and E ₁be greater than E ₂,

When the output voltage of controllable direct current power supply is E ₁, electric current corresponding to this series connection closed-loop path is I ₁, the voltage measuring fixed value resistance (2) two ends obtains measuring voltage U ₁₁, the voltage measuring measured resistance (1) two ends obtains measuring voltage U ₂₁,

When the output voltage of controllable direct current power supply is E ₂, electric current corresponding to this series connection closed-loop path is I ₂, the voltage measuring fixed value resistance (2) two ends obtains measuring voltage U ₁₂, the voltage measuring measured resistance (1) two ends obtains measuring voltage U ₂₂, according to formula calculate the resistance R obtaining and eliminate the rear measured resistance (1) of interference _{x '};

Described electric current I ₁and I ₂pulsewidth identical, be 1 second;

Described electric current I ₁amplitude be 1A;

Described electric current I ₂amplitude be 5A;

Electric current I ₁and I ₂export continuously alternately, the cycle of constituting is the periodic current of 2 seconds.

2. a kind of micro-resistance high-precision measuring method based on double-current voltage ratio method according to claim 1, it is characterized in that, the described resistance calculating measured resistance (1), its detailed process is, according to formula calculate the resistance R obtaining measured resistance (1) _x.

3. realize the measuring system of a kind of micro-resistance high-precision measuring method based on double-current voltage ratio method according to claim 1, it is characterized in that, described measuring system comprises measured resistance (1), fixed value resistance (2), adjustable current-limiting resistance (3), controllable electric power (9), filter amplifier (4), A/D converter (5), Single Chip Microcomputer (SCM) system (6), display (7) and operation keyboard (8), one end ground connection of described measured resistance (1), the other end of measured resistance (1) is connected with one end of fixed value resistance (2), the other end of this fixed value resistance (2) is connected with one end of adjustable current-limiting resistance (3), the other end of adjustable current-limiting resistance (3) is connected with the positive source output terminal of controllable electric power (9), the power cathode input end of controllable electric power (9) is connected with the voltage control signal output terminal of Single Chip Microcomputer (SCM) system (6), four-wire ohm measuring method is adopted to gather the terminal voltage signal of fixed value resistance (2), and this voltage signal is sent to filter amplifier (4), adopt four-wire ohm measuring method to gather the terminal voltage signal of measured resistance (1), and this voltage signal is sent to filter amplifier (4), the signal output part of filter amplifier (4) is connected with the input end of analog signal of A/D converter (5), the digital signal output end of described A/D converter (5) is connected with the collection signal input end of Single Chip Microcomputer (SCM) system (6), the display output terminal of described Single Chip Microcomputer (SCM) system (6) is connected with the signal input part of display (7), and described operation keyboard (8) signal output part is connected with the signal input part of Single Chip Microcomputer (SCM) system (6).