CN109142876A - Resistance measuring circuit and resistivity-measuring devices - Google Patents
Resistance measuring circuit and resistivity-measuring devices Download PDFInfo
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- CN109142876A CN109142876A CN201811289050.0A CN201811289050A CN109142876A CN 109142876 A CN109142876 A CN 109142876A CN 201811289050 A CN201811289050 A CN 201811289050A CN 109142876 A CN109142876 A CN 109142876A
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/08—Measuring resistance by measuring both voltage and current
Abstract
The invention discloses a kind of resistance measuring circuit and resistivity-measuring devices, wherein, resistance measuring circuit includes: data acquisition module, with testing resistance connecting pin, reference resistance connecting pin and data signal output, for acquiring the current or voltage of testing resistance and reference resistance, testing resistance connecting pin and reference resistance connecting pin and output end electrical isolation；Input, output end, power supply are mutually isolated.Measurement module is connect with data signal output, and the resistance value of testing resistance is measured for the current or voltage of measurement data signals output end output.Since data acquisition realizes that electrical isolation can apply different voltages or electric current with DATA REASONING, different voltage or electric current can be exported simultaneously, and datum mark can be selected according to the physics and mathematical definition of resistance, reduce DM EMI, common mode interference and noise jamming, greatly facilitate resistance measurement, measurement range is expanded, measurement error can also be effectively reduced, improves measurement accuracy.
Description
Technical field
The present invention relates to electromagnetic measurement technical fields, and in particular to arrives a kind of resistance measuring circuit and resistivity-measuring devices.
Background technique
Resistive element is can to use resistance member in dissipative cell, such as light bulb, electric heater of inhibition etc. to electric current
Part is as its circuit model.The electric current I for flowing through resistive element according to Ohm's law is directly proportional to the voltage U at resistance both ends,
Almost all of electrical equipment has resistive element, even if conductor is also a kind of equivalent without special resistor
Resistance measures the wheatstone bridge of resistance value, the double bridge of the small resistance of measurement, measurement so resistance apparatus generally uses
The insulation resistance meter (megameter) of insulation resistance, the ground resistance measuring instrument (earth resistance meter) of measurement of Grounding Resistance, measurement electricity
Ohmmeter, milliohmmeter, micro-ohm table, resistivity measuring instrument, insulation resistance monitor and the multimeter of resistance are all measurement resistance
Instrument, many electrical measuring instruments all have the function of resistance measurement in fact.It requires to measure resistance in many scenes.
However, in actual measurement, when being measured using above-mentioned instrument, it will usually which there are what resistance measurement was not allowed to show
As, and then influence the expansion of follow-up work.
Therefore, resistance how is accurately measured as technical problem urgently to be resolved.
Summary of the invention
For this purpose, according in a first aspect, present example provides a kind of resistance measuring circuit, comprising: data acquisition module,
With testing resistance connecting pin, reference resistance connecting pin and data signal output, for acquiring the testing resistance and institute
State the current data or voltage data of reference resistance, the testing resistance connecting pin and the reference resistance connecting pin and the number
According to signal output end electrical isolation；Measurement module is connect with the data signal output, defeated for measuring the data-signal
The current data or voltage data of outlet output, to measure the resistance value of testing resistance.
Optionally, data acquisition module includes: the first isolated amplifier, has the first input for connecting testing resistance
End and the first output end being isolated with the first input end；Second isolated amplifier has for connecting reference resistance
Two input terminals and the second output terminal being isolated with second input terminal；First output end is isolated with the second output terminal
Or altogether；The measurement module is arranged between first output end and the second output terminal, for acquiring described first
The voltage and current of current difference or voltage difference between output end and the second output terminal and the output of the first output end or the
The voltage or electric current of two output ends output.
Optionally, resistance measuring circuit further includes power module, for providing current or voltage；The first isolation amplification
The first input end of module for connect with one end of the testing resistance, one end of the power module for it is described to be measured
The other end of resistance connects；First Isolation Amplifier Module further includes third input terminal, the third input terminal and the electricity
The other end of source module connects；Second input terminal of second Isolation Amplifier Module is used to connect with one end of the reference resistance
It connects, one end of the power module with the other end of the reference resistance for connecting；Second Isolation Amplifier Module is also wrapped
The 4th input terminal is included, the 4th input terminal is connect with the other end of the power module.
Optionally, the measurement module includes current measuring unit, for measuring first output end and described second
The electric current of current difference and the output of the first output end between output end and the electric current of second output terminal output.
Optionally, resistance measuring circuit further includes power module, for providing current or voltage；First isolation is put
Big module further includes third input terminal, and the first input end of first Isolation Amplifier Module is for one with the testing resistance
End connection, the third input terminal with the other end of the testing resistance for connecting；Second Isolation Amplifier Module is also wrapped
The 4th input terminal is included, the second input terminal of second Isolation Amplifier Module with one end of the reference resistance for connecting, institute
The 4th input terminal is stated for connecting with the other end of the reference resistance.
Optionally, the third input terminal is connect with second input terminal；One end of the power module and described the
The connection of one input terminal, the other end of the power module are connect with the 4th input terminal.
Optionally, the measurement module includes voltage measurement unit, for measuring the voltage of the first output end output
Voltage difference between the voltage and the first output end and second output terminal of second output terminal output.Optionally, resistance
Measuring circuit, further includes: data processing module is connect with the measurement module, for according to the voltage difference or current difference measured
Obtain the resistance value of testing resistance.
According to second aspect, the embodiment of the invention provides a kind of resistivity-measuring devices, comprising: apparatus body；On and
State resistance measuring circuit described in first aspect any one.
Resistance measuring circuit and resistivity-measuring devices provided in an embodiment of the present invention, data acquisition module have electricity to be measured
Connecting pin, reference resistance connecting pin and data signal output are hindered, for acquiring the testing resistance and the reference resistance
Current data or voltage data, the testing resistance connecting pin and the reference resistance connecting pin and the data-signal export
Hold electrical isolation；Measurement module is connect with the data signal output, for measuring the data signal output output
Current data or voltage data, to measure the resistance value of testing resistance.Since data acquisition realizes that electrical isolation can with DATA REASONING
To apply different voltages or electric current, while different voltage or electric current can be exported, and it is possible to according to the physics sum number of resistance
Definition is learned to select datum mark, resistance measurement is greatly facilitated, expands measurement range, can also effectively reduce measurement and miss
Difference also improves measurement accuracy.
Detailed description of the invention
It, below will be to specific in order to illustrate more clearly of the specific embodiment of the invention or technical solution in the prior art
Embodiment or attached drawing needed to be used in the description of the prior art be briefly described, it should be apparent that, it is described below
Attached drawing is some embodiments of the present invention, for those of ordinary skill in the art, before not making the creative labor
It puts, is also possible to obtain other drawings based on these drawings.
Fig. 1 is that prior art voltammetry measures resistance method for externally；
Fig. 2 is that prior art voltammetry measures resistance inscribed methods；
Fig. 3 is the method that prior art resistance box and ammeter measure resistance；
Fig. 4 is the method that prior art resistance box and voltmeter measure resistance；
Fig. 5 is that prior art zero method wheatstone bridge measures resistance principle circuit；
Fig. 6 is the schematic circuit that prior art zero method double bridge measures resistance；
Fig. 7 is the schematic diagram of resistance measuring circuit of the invention；
Fig. 8 is the schematic diagram of another resistance measuring circuit of the invention；
Fig. 9 is the schematic diagram of another resistance measuring circuit of the invention；
Figure 10 is resistivity-measuring devices front panel of the invention；
Figure 11 is resistivity-measuring devices rear panel of the invention.
Specific embodiment
Technical solution of the present invention is clearly and completely described below in conjunction with attached drawing, it is clear that described implementation
Example is a part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, ordinary skill
Personnel's every other embodiment obtained without making creative work, shall fall within the protection scope of the present invention.
The inaccurate situation of measurement is frequently encountered during measuring in practice to resistance, applicant is by deeply grinding
Study carefully existing measurement method, it is found that existing measurement method has certain measurement error, causes measurement inaccurate, existing survey
Amount method usually has following several:
The classical measurement method of resistance is voltammetry, and the principle of this method is exactly partial circuit Ohm's law and closure electricity
The Ohm's law on road.
It is exactly to determine according to formula (2) that voltammetry, which measures resistance,.
R=U/I (2)
In formula: R is the resistance value for being measured resistance；U is the voltage value of voltmeter measurement；I is the electric current measured with ammeter
Value.
Due to the partial pressure and shunting function of voltmeter and amperemeter inner resistance, measurement error is produced, therefore voltammetry is divided again
For inscribed methods and method for externally, the wiring of method for externally is as shown in Figure 1, as can be seen that ammeter connects in measured resistance and electricity in figure
The outside of table wiring is pressed, shown in the error such as formula (3) that this measurement method generates:
As can be seen from the above equation, the reason of generating measurement error is that voltmeter internal resistance shunts, so only working as EV> > RxWhen
Just use the voltammetry of external impressed current table.Inscribed methods are as shown in Figure 2.It can be seen from the figure that ammeter connect tested resistance with
The inside that voltmeter connects.Shown in the error such as formula (4) that this measurement method generates.
As can be seen from the above equation, the reason of generating measurement error is ammeter partial pressure, so only working as Rx> > RAWhen just adopt
With the voltammetry of inscribed ammeter.
Method of substitution: resistance is measured using voltammetry, no matter ammeter inner connection or external ammeter can all cause measurement
Error can reduce these errors using comparative method for measuring resistance, and when test first accesses certain testing resistance, write down electric in circuit
Then testing resistance is changed into resistance box by the reading of table, adjust resistance box, makes the reading of ammeter and original reading one in circuit
Sample, such resistance box resistance value are exactly the resistance value of testing resistance, and method of substitution, which can be divided into, measures using ammeter and use voltmeter
Two kinds of measurement, the wiring measured with voltmeter is as shown in figure 3, S1 switch is used to switch testing resistance and reference resistance R in figureNSuch as
Resistance box, S2 switch is used to Switching Power Supply, to switch testing resistance RXWith reference resistance RN.A is ammeter, for measuring electricity
Stream.The wiring measured with voltmeter is as shown in figure 4, in figure other than replacing ammeter A with voltage Table V, other are all.It replaces
It is first to access testing resistance for method, writes down the reading of ammeter in circuit, testing resistance is then changed into resistance box, adjusts resistance
Case makes in circuit the reading of ammeter and original reading, and such resistance box resistance value is exactly the resistance value of testing resistance.In this way, to
The measurement of measuring resistance and resistance box cannot carry out simultaneously, can be because the variation that the variation and measurement of power supply are adjusted increases measurement error
Zero method: by testing resistance and reference resistance such as resistance box simultaneously detection circuit for access, pass through adjusting reference electricity
The size of resistance makes nulling instrument nulling, and the value for being at this moment tested unknown resistance is to be equal to the value of measuring resistance.This measurement method
Measurement accuracy depends primarily on the accuracy of measuring resistance and the sensitivity of nulling instrument.The internal impedance of power supply and nulling instrument
Internal impedance all will not influence measurement result.The method of most typical measurement resistance, is exactly using electric bridge, this also resistance accurate measurement
Common method.Electric bridge is divided into single bridges and double bridge.Single bridges are also referred to as Wheatstone bridge, working principle as figure 5 illustrates, it
Bridge is by unknown testing resistance R1With adjustable known resistance R2、R3And R4Composition.Tetra- vertex a, b, c, d are known as in figure
Bridge top, I1、I2、I3、I4For the electric current for flowing through each bridge arm, R2And R4It is made of several fixed resistances that can be converted, R2/R3
Several different fixed proportions, therefore R can be formed by adjusting2And R4Referred to as ratio arms, or referred to as range converter,
Different ratio arms is selected namely to select different ranges.R3The variable resistance of multiple disks, referred to as Measuring plate is made.G is to refer to
Zero instrument, also referred to as galvanometer, effect are whether detection b and d point has electric current, and adjusting electric bridge is designated as zero until zero indicator, also
It is zero method.The equilibrium condition and equation of equilibrium of single bridges: work as I1、I2、I3、I4When for arbitrary value, there is electric current in each branch
It flows through, also there is electric current I in galvanometerg.Adjust I2、I3、I4It can make Ig=0, electric bridge is in equilibrium state, bridge balance meaning at this time
Taste: b with d two o'clock current potential is identical, Ig=0, so, I1=I2, I3=I4, Uab=Uad,Ubc=Udc.It follows that I1R1=
I3R3,I2R2=I4R4, two formulas are divided by, obtain
Then
Therefore it can obtain:
By formula (6) it can be seen that adjusting after resistance makes bridge balance, testing resistance RX(resistance R in Fig. 51) can be by electric bridge
The readouts of three bridge arms find out.Here it is the working principles of electric bridge.Formula (5) is known as bridge balance condition, equation of equilibrium table
It is shown as: R1R4=R2R3, i.e., equal with respect to two bridge arm products.To obtain a property of balanced bridge: the equilibrium condition of electric bridge
Only determined by the relationship between each parameter of bridge arm, and it is unrelated with the internal resistance of supply voltage and zero indicator.
Single bridges the characteristics of and purposes: using single bridges measure resistance, when measured resistance is less than 10 Ω, lead electricity
Resistance cannot be ignored with the contact resistance of electric bridge junction.If lead resistance, contact resistance are larger, measurement result will be made
Generate large error.
Double bridge is exclusively used in measuring small resistance.If necessary to measure small resistance, such as motor or the resistance of transformer winding,
When the resistance of current divider, single bridges cannot be used, it should double bridge is used, because double bridge can eliminate lead bring error.Double bridge
Working principle as shown in fig. 6, RxIt is testing resistance, RNIt is reference resistance, RNAnd RxFour terminal wiring are all made of, double electricity are connected to
On the corresponding terminal of bridge, RNAnd RxBetween connecting line r be known as cross-line.R3And R3' it is the two adjustable bridge arms to link, by more
A Measuring plate composition, R3Referred to as outer relatively arm, R3' it is known as interior relatively arm, R4And R4' it is ratio arms, R4Referred to as outer relatively arm, R4′
Referred to as in relatively arm, they should be arranged in it is same numerically.By RNAnd RxR is adjusted after access3And R3' make galvanometer zero, so
After calculate RxValue, calculation formula be formula (7).
The equilibrium condition and equation of equilibrium of double bridge are similar with single bridges, no longer repeat.
The characteristics of double bridge and purposes:
Double bridge be calibration resistor and measured resistance device current feed are included in working power circuit do not participate in it is flat
Weighing apparatus,.And the current potential lead of the two is included in each bridge arm, since arm resistance each in measurement process all has biggish electricity
Resistance value, therefore the influence of current potential lead resistance can be ignored.From formula (7) it may be concluded that the double bridge error of indication with
Measuring resistance RNExcept, mainly by R3And R4Alignment error and link resistance value r determine.Due to actually adjusting R3=R3′
And R4=R4' difficult very big, r is it is not possible that absolute value is zero (providing it in 0.01 Ω or less in design), so the measurement of double bridge
Accuracy is not generally high.To increase the working power of electric bridge to improve the galvanometric sensitivity of electric bridge, but operating voltage
It is excessively high, the temperature of resistance can be made to increase, influence the stabilization of resistance.
Therefore, applicant proposed a kind of resistance measuring circuits.As shown in fig. 7, the resistance measuring circuit may include: number
According to acquisition module 10, there is testing resistance RXConnecting pin 11, reference resistance RNConnecting pin 12 and data signal output 13 are used
In the acquisition testing resistance RXWith the reference resistance RNCurrent data or voltage data, the testing resistance RXConnecting pin
The 11 and reference resistance RNConnecting pin 12 and 13 electrical isolation of data signal output；Measurement module 20, with the number
It is connected according to signal output end 13, for measuring the current data or voltage data that the data signal output 13 exports, to survey
Measure testing resistance RXResistance value.
Data acquisition realizes that electrical isolation can apply different voltages or electric current with DATA REASONING, while can export difference
Voltage or electric current greatly facilitate resistance survey and it is possible to select datum mark according to the physics of resistance and mathematical definition
Amount, expands measurement range, can also effectively reduce measurement error, also improve measurement accuracy.
In an alternate embodiment of the invention, data acquisition module 10 includes: the first isolated amplifier U1, have to be measured for connecting
Resistance RXFirst input end and the first output end for being isolated with the first input end；Second isolated amplifier U2, have and be used for
Connect reference resistance RNThe second input terminal and the second output terminal be isolated with second input terminal；First output end with
The second output terminal isolation, but as needed can be by line altogether；The setting of measurement module 20 is in first output
Between end and the second output terminal, for acquiring the voltage and current and the second output terminal that first output end exports
The voltage or current of output and current difference or voltage difference between both.
In the present embodiment, resistance measuring circuit can measure resistance using poor stream method, can also use differential pressure
Method measures, and needs in measurement for testing resistance RXWith reference resistance RNPower supply is provided, to acquire testing resistance RXAnd reference
Resistance RNCurrent data or voltage data.
Specifically, as shown in figure 8, poor stream method can be measured using following circuit, first Isolation Amplifier Module
First input end be used for and the testing resistance RXOne end connection, one end of the power module is used for and the electricity to be measured
Hinder RXThe other end connection；First Isolation Amplifier Module further includes third input terminal, the third input terminal and the electricity
The other end of source module connects；Second input terminal of second Isolation Amplifier Module is used for and the reference resistance RNOne end
One end of connection, the power module is used for and the reference resistance RNThe other end connection；Second Isolation Amplifier Module
It further include the 4th input terminal, the 4th input terminal is connect with the other end of the power module.The measurement module includes electricity
Flow metering unit, for measure first output end output electric current and second output terminal output electric current and it
Current difference between the electric current of the two.
Specifically, as shown in figure 9, differential pressure method can be measured using following circuit, first Isolation Amplifier Module
It further include third input terminal, the first input end of first Isolation Amplifier Module is used for and the testing resistance RXOne end connect
It connects, the third input terminal is used for and the testing resistance RXThe other end connection；Second Isolation Amplifier Module further includes
Second input terminal of the 4th input terminal, second Isolation Amplifier Module is used for and the reference resistance RNOne end connection, institute
The 4th input terminal is stated to be used for and the reference resistance RNThe other end connection；The third input terminal and second input terminal connect
It connects；One end of the power module is connect with the first input end, the other end of the power module and the 4th input
End connection.The measurement module includes voltage measurement unit, for measuring the voltage and described the of first output end output
The voltage of two output ends output and the voltage difference between both.
Above-mentioned difference stream method circuit and isolated amplifier input circuit in differential pressure method circuit, output loop, electric power loop and
Ground is completely isolated, can effectively reduce direct current offset, leakage of current and zero drift, reduces the error of zero, also directly
Reduce measurement error.The output impedance of influence due to input impedance and to(for) measurement is very big, input impedance and output impedance
It can according to need design, the input impedance of voltage is larger, and the input impedance of electric current is smaller, is conducive to reduce measurement mistake in this way
Difference.Further, using input circuit, output loop, electric power loop and ground is completely isolated can also effectively reduce DM EMI
And common mode interference, improve measurement accuracy.
As optional embodiment, data processing module is connect with the measurement module, for according to the voltage difference measured
Or current difference obtains testing resistance RXResistance value.In the present embodiment, alleged data processing module may include: A/D converter,
Any one in the measurements such as data collecting card part and single-chip microcontroller, Embedded A M, tablet computer or computer, in the present embodiment
In, however it is not limited to above-mentioned data processing module, as long as corresponding resistor can be calculated in this reality according to corresponding current or voltage
Apply the protection scope of example.
In the following, in conjunction with resistance measurement method in the prior art, the resistance measuring circuit that is described in detail in this implementation has
Beneficial effect.
Resistance measuring circuit in the present embodiment avoids compared with voltammetry since ammeter and voltmeter internal resistance are brought
Measurement error.No matter ammeter is inscribed it can be seen from above-mentioned (2), formula (3), formula (4), specific reference to Fig. 2 or external tool
Body referring to Fig. 1, can all bring measurement error.Method of the invention, reference resistance RNWith testing resistance RXSeries connection, series circuit
Middle electric current is equal, without measuring electric current, therefore, can thoroughly eliminate the influence of amperemeter inner resistance, reference resistance RNWith electricity to be measured
Hinder RXSeries connection is respectively connected to isolated amplifier, and the input impedance of isolated amplifier is almost equal, can ignore the shadow of input impedance
It rings, and then more can accurately measure the resistance value of resistance.
Resistance measuring circuit in the present embodiment is compared with method of substitution: method of substitution is first to access testing resistance RX, write down electricity
The reading of ammeter in road, then testing resistance RXIt changes resistance box into, adjusts resistance box, make in circuit the reading of ammeter and original
Readings are consistent, and such resistance box resistance value is exactly testing resistance RXResistance value.However, testing resistance RXMeasurement with resistance box cannot
It carries out simultaneously, it can be because the variation that the variation and measurement of power supply are adjusted increases measurement error.Using the resistance measurement of the present embodiment
Circuit, reference resistance RNWith testing resistance RXIt measures simultaneously, the variation that can be adjusted to avoid the variation and measurement of power supply in method of substitution
Increase measurement error.Also, there are two the errors of zero for the method for substitution in the prior art, and the resistance measuring circuit in the application makes
With isolated amplifier, input, output are completely isolated with power supply, almost without the error of zero.
For resistance measuring circuit in the present embodiment compared with zero method, zero method is exactly by testing resistance RX and reference resistance
RNSimultaneously in detection circuit for access, by adjusting reference resistance RNSize, make nulling instrument nulling, at this moment testing resistance RX's
It is equal to reference resistance RNValue.Zero method is zero that the sensitivity of nulling instrument can indicate, if using sensitivity for 1
×10-5Nulling instrument nulling, when use sensitivity for 1 × 10-7Nulling instrument when, the possible higher instrument of sensitivity
Table be directed toward non-zero, due to zero be it is opposite, only with respect to the sensitivity of certain nulling instrument.The measurement accuracy of zero method
Depend primarily on the accuracy of measuring resistance and the sensitivity of nulling instrument.
The circuit of the most typical measurement resistance of zero method is electric bridge, and electric bridge is divided into single bridges and double bridge.Its working principle
As shown in figure 5, it is calculated such as formula (6), by formula (6) it can be seen that adjusting after resistance makes bridge balance, testing resistance RX, can
It is found out with the readout by the three of electric bridge bridge arm.Here it is the working principles of electric bridge.Formula (5) is known as bridge balance condition, puts down
The formula that weighs indicates are as follows: R1R4=R2R3, i.e., equal with respect to two bridge arm products.To obtain a property of balanced bridge: electric bridge
Equilibrium condition only determines by the relationship between each parameter of bridge arm, and unrelated with the internal resistance of supply voltage and zero indicator.
Resistance is measured using single bridges, when measured resistance is less than 10 Ω, lead resistance, the electricity of the contact with electric bridge junction
Resistance cannot be ignored.If lead resistance, contact resistance are larger, measurement result will be made to generate large error.Bridge balance item
Part is zero indicator nulling, for accurate judgement balance, it should using highly sensitive zero indicator.Bridge sensitivity and bridge voltage
Related supply voltage is higher, and sensitivity is also higher.
Double bridge can eliminate lead bring error, and double bridge is exclusively used in measuring small resistance.The working principle of double bridge is such as
Shown in Fig. 6, calculation formula is formula (7).Double bridge is that calibration resistor and measured resistance device current feed are included in work
Electric power loop does not participate in balance,.And the current potential lead of the two is included in each bridge arm, due to bridge arm electricity each in measurement process
Resistance all has biggish resistance value, therefore the influence of current potential lead resistance can be ignored.From formula (7) it may be concluded that
The double bridge error of indication and reference resistance RNExcept, mainly by R3And R4Alignment error and link resistance value r determine.Due to
Actually adjust R3=R3' and R4=R4' difficult very big, r is it is not possible that absolute value is zero, so the accuracy of measurement one of double bridge
As it is not high.
Resistance measuring circuit in the present embodiment overcomes single bridges since isolated amplifier has very high input impedance
The influence of lead resistance and contact resistance to measurement result.Due to power amplifier to output and input circuit completely isolated, mention
To improve sensitivity, input does not improve the voltage of height output, resistor power in circuit will not be made to improve, so isolated amplifier
Isolation also solve single bridges and need to improve voltage to improve sensitivity, and improve voltage and prevent the power of resistance from holding
The contradiction received.Synchronous adjustment resistance R is eliminated in resistance measuring circuit in the present embodiment3、R3' and R4、R4' and cross-line electricity
Resistance value r.So effectively overcoming double bridge defect.
The embodiment of the invention provides a kind of resistivity-measuring devices, may include: apparatus body；And such as above-mentioned implementation
Resistance measuring circuit described in any one of example.In the present embodiment, apparatus body can be the cabinet of resistivity-measuring devices.
Figure 10 illustratively shows the case front panel of resistivity-measuring devices.Left upper portion and middle part are regulated power supply, and top is electricity
Flow table and voltmeter are used to refer to the electric current and voltage of voltage output, ammeter in the following, the left side be electric current output key switch,
Electric current exports when under peace, naturally it is also possible to other switches, such as toggle switch, rotary switch, button switch, can also with after
Electric appliance, as long as can control the output and stopping of power supply.It is indicator light that electric current output key, which switchs the right side, when power supply has electric current
When output, lamp is bright, and when the electric current of power supply stops output, lamp goes out.It is that electric current is thick below electric current output key switch and indicator light
Knob and electric current fine tuning knob are adjusted, for adjusting the size of electric power outputting current, current many regulated power supplies are all digital program controlled
Power supply, some use number key, and some is all possible using raising and lowering key as long as being able to achieve corresponding function.Voltmeter
In the following, the left side is voltage output key switch, voltage output when under peace, naturally it is also possible to other switches, such as toggle switch, rotation
Pass, button switch etc. are turned on, relay can also be used, as long as can control the output and stopping of power supply.Electric current output key
Switching the right side is indicator light, and when power supply has voltage output, lamp is bright, and when the voltage of power supply stops output, lamp goes out.Voltage output
It is voltage coarse adjustment knob and voltage fine knob below key switch and indicator light, for adjusting the big of electric power output voltage
Small, current many regulated power supplies are all digital program controlled power supplys, and some uses number key, and some uses raising and lowering key, as long as
It is able to achieve corresponding function, is all possible.Left side is in the following, be from left to right followed successively by power switch, power supply indicator, power supply output
It is high-end, power supply export low side, power switch is on or off the power supply of regulated power supply, when power supply indicator is bright, table
Show that the power supply of regulated power supply is opened, indicates that the power supply of regulated power supply disconnects when power supply indicator goes out.Middle panel and
The upper surface of right part is display screen, and liquid crystal display can show various parameters, and the difference of electric current, the voltage such as applied, measurement flows, is poor
Pressure, the parameters such as resistance of measurement, this only should display unit, can be shown with LCD window, LED can be used and show, can also
To be shown with pointer instrument；Also desktop computer tablet computer, laptop or other display devices can be used, only
It wants correctly show related data.It can also show signal waveform, liquid crystal display can be used in the display for waveform
Device also can be used oscilloscope tube and show, desktop computer tablet computer, laptop or other displays also can be used
Part, as long as waveform correlation can correctly be shown.It is the adjustment switch of reference resistance or measuring resistance below display screen, for string
Connection has the ten of 11 into change-over switch, has drawn 5 in figure, effect is to adjust the resistance value of reference resistance or measuring resistance, makes electricity
The resistance value of reference resistance or measuring resistance is close with the resistance value of tested unknown resistance in road, due to difference measurement range of the invention
It is very big, according to measurement accuracy difference, the range of the resistance value difference of different reference resistance or measuring resistance also can be set, therefore
The number of switch can increase or decrease, and the effect of these switches is identical with the on-off action of resistance box, so being opened with others
It is also possible to close device, such as relay, key switch, resistor network etc..It is resistance input terminal below adjustment switch, makes
It is the input of four ends, if low measurement accuracy, both ends input also can be used.The input terminal on the left side is tested unknown resistance
Input terminal, RXL1WithRXL2For current input terminal, RXP1And RXP2For voltage input end.For connecting tested unknown resistance.The right side
Input terminal be to refer to or the input terminal of measuring resistance, RNL1And RNL2For current input terminal, RNP1And RNP2For voltage input end.With
To connect reference or measuring resistance.When internal reference or measuring resistance are empty, external reference or standard electric can be used
Resistance, these references or measuring resistance can be by tracing to the source or calibrating, the measurement of higher precision may be implemented in this way, can also examine
Determine measuring resistance.Figure 11 is rear panel, and upper left face is power outlet or fuse, other forms also can be used, for example make
With the power outlet with fuse.Lower-left face is ground connection knob, has to provide according to ground connection, and reliable ground connection dress is arranged
It sets.Bottom right face is communication interface, has USB, RJ45, RS232 etc. that can be arranged as required.As long as being able to satisfy communicating requirement
It can be with.Resistance is measured using the differential technique with isolated amplifier.Can be there are two types of form: one is differences to flow for differential technique
Method is exactly the method measurement resistance with measurement difference current, is exactly the method measurement with measurement difference voltage one is differential pressure method
Resistance.The measuring principle of both methods be it is the same, the signal type only measured is different, and measurement result is all resistance.
Although the embodiments of the invention are described in conjunction with the attached drawings, but those skilled in the art can not depart from this hair
Various modifications and variations can be made in the case where bright spirit and scope, and such modifications and variations are each fallen within by appended claims
Within limited range.
Claims (9)
1. a kind of resistance measuring circuit characterized by comprising
Data acquisition module has testing resistance connecting pin, reference resistance connecting pin and data signal output, for acquiring
The current data or voltage data of the testing resistance and the reference resistance, the testing resistance connecting pin and the reference electricity
Hinder connecting pin and the data signal output electrical isolation；Input, output end and power supply are mutually isolated.
Measurement module is connect with the data signal output, for measuring the electric current number of the data signal output output
According to or voltage data, to measure the resistance value of testing resistance.
2. resistance measuring circuit as described in claim 1, which is characterized in that the data acquisition module includes:
First isolated amplifier has for connecting the first input end of testing resistance and being isolated with the first input end
One output end；
Second isolated amplifier has for connecting the second input terminal of reference resistance and being isolated with second input terminal
Two output ends；First output end is isolated or altogether with the second output terminal；
The measurement module is connect with first output end and the second output terminal respectively, for measuring first output
The voltage or electric current and second that current difference or voltage difference and the first output end between end and the second output terminal export are defeated
The voltage or electric current of outlet output.
3. resistance measuring circuit as claimed in claim 2, which is characterized in that further include power module, for provide electric current or
Voltage；
The first input end of first Isolation Amplifier Module with one end of the testing resistance for connecting, the power module
One end for being connect with the other end of the testing resistance；
First Isolation Amplifier Module further includes third input terminal, the other end of the third input terminal and the power module
Connection；
Second input terminal of second Isolation Amplifier Module with one end of the reference resistance for connecting, the power module
One end for being connect with the other end of the reference resistance；
Second Isolation Amplifier Module further includes the 4th input terminal, the other end of the 4th input terminal and the power module
Connection.
4. resistance measuring circuit as claimed in claim 3, which is characterized in that
The measurement module includes current measuring unit, for measuring between first output end and the second output terminal
The electric current of the electric current and second output terminal output of current difference and first output end output.
5. resistance measuring circuit as claimed in claim 2, which is characterized in that further include power module, for provide electric current or
Voltage；
First Isolation Amplifier Module further includes third input terminal, and the first input end of first Isolation Amplifier Module is used for
It is connect with one end of the testing resistance, the third input terminal with the other end of the testing resistance for connecting；
Second Isolation Amplifier Module further includes the 4th input terminal, and the second input terminal of second Isolation Amplifier Module is used for
It is connect with one end of the reference resistance, the 4th input terminal with the other end of the reference resistance for connecting.
6. resistance measuring circuit as claimed in claim 5, which is characterized in that
The third input terminal is connect with second input terminal；
One end of the power module is connect with the first input end, the other end of the power module and the 4th input
End connection.
7. such as resistance measuring circuit described in claim 5 or 6, which is characterized in that the measurement module includes voltage measurement list
Member, for measuring the voltage of first output end output and the voltage of second output terminal output, the first output end and the
Voltage difference between two output ends.
8. the resistance measuring circuit as described in claim 1-7 any one, which is characterized in that further include:
Data processing module is connect with the measurement module, for obtaining testing resistance according to the voltage difference or current difference that measure
Resistance value.
9. a kind of resistivity-measuring devices characterized by comprising
Apparatus body；And
Resistance measuring circuit as described in claim 1-8 any one.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811289050.0A CN109142876A (en) | 2018-10-31 | 2018-10-31 | Resistance measuring circuit and resistivity-measuring devices |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811289050.0A CN109142876A (en) | 2018-10-31 | 2018-10-31 | Resistance measuring circuit and resistivity-measuring devices |
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Family
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| CN201811289050.0A Pending CN109142876A (en) | 2018-10-31 | 2018-10-31 | Resistance measuring circuit and resistivity-measuring devices |
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| CN110320410A (en) * | 2019-07-15 | 2019-10-11 | 天津大学 | A kind of LCR measuring device and method based on transformer lead compensator bridge |
| CN111257641A (en) * | 2020-02-25 | 2020-06-09 | 东风电子科技股份有限公司 | Wide resistance range signal acquisition circuit and corresponding acquisition method |
| CN111337747A (en) * | 2020-03-23 | 2020-06-26 | 东软睿驰汽车技术（沈阳）有限公司 | Device and method for measuring resistance, vehicle-mounted controller and electric vehicle |
| CN112098767A (en) * | 2020-11-18 | 2020-12-18 | 北京天创凯睿科技有限公司 | Safety detection circuit of ignition device and safety detection equipment of ignition device |
| CN112505421A (en) * | 2020-11-16 | 2021-03-16 | 广东电网有限责任公司 | Measuring circuit for direct current resistance of dry-type air-core reactor |
| CN113866506A (en) * | 2021-09-23 | 2021-12-31 | 安测半导体技术(江苏)有限公司 | Test fixture contact impedance detection method and device |
| CN114217113A (en) * | 2021-11-25 | 2022-03-22 | 广西电网有限责任公司电力科学研究院 | Improved direct current resistance box voltage comparison measurement method and system |
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| CN111257641A (en) * | 2020-02-25 | 2020-06-09 | 东风电子科技股份有限公司 | Wide resistance range signal acquisition circuit and corresponding acquisition method |
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| CN112098767A (en) * | 2020-11-18 | 2020-12-18 | 北京天创凯睿科技有限公司 | Safety detection circuit of ignition device and safety detection equipment of ignition device |
| CN112098767B (en) * | 2020-11-18 | 2021-03-05 | 北京天创凯睿科技有限公司 | Safety detection circuit of ignition device and safety detection equipment of ignition device |
| CN113866506A (en) * | 2021-09-23 | 2021-12-31 | 安测半导体技术(江苏)有限公司 | Test fixture contact impedance detection method and device |
| CN114217113A (en) * | 2021-11-25 | 2022-03-22 | 广西电网有限责任公司电力科学研究院 | Improved direct current resistance box voltage comparison measurement method and system |
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