CN102707153A - Contact resistance measuring system and method based on voltage-frequency conversion method - Google Patents

Contact resistance measuring system and method based on voltage-frequency conversion method Download PDF

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Publication number
CN102707153A
CN102707153A CN2012102183188A CN201210218318A CN102707153A CN 102707153 A CN102707153 A CN 102707153A CN 2012102183188 A CN2012102183188 A CN 2012102183188A CN 201210218318 A CN201210218318 A CN 201210218318A CN 102707153 A CN102707153 A CN 102707153A
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China
Prior art keywords
voltage
converter
frequency
uut
chip microcomputer
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CN2012102183188A
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Chinese (zh)
Inventor
任万滨
曹晟
王鹏
支宏旭
武剑
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Harbin Institute of Technology
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Harbin Institute of Technology
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Priority to CN2012102183188A priority Critical patent/CN102707153A/en
Publication of CN102707153A publication Critical patent/CN102707153A/en
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Abstract

The invention discloses a contact resistance measuring system and method based on a voltage-frequency conversion method and relates to a contact resistance measuring system and method which are used for solving the problem that a contact resistance measuring method is poor in data stability and low in accuracy. According to the invention, a variable gain voltage amplifier is adopted for acquiring and amplifying the voltages U of the two ends of a to-be-measured component; a voltage follower is adopted for acquiring a voltage between the to-be-measured component and a standard current-detecting resistor, and after being isolated, the voltage is input to an AD (analog to digital) converter, and then the voltage is converted into a digital quantity ix through the AD converter; a voltage-frequency converter is adopted for converting the amplified voltages into frequency signals, and carrying out timing counting on the frequency signals so as to obtain the digital quantities Ux of the voltages U of the two ends of the to-be-measured component; a digital quantity Ix of an exciting current is calculated acceding to the digital quantities Ux; and then the resistance value of the to-be-measured component is obtained, thereby realizing the contact resistance measurement based on the voltage-frequency conversion method. The system and method disclosed by the invention are applicable to the measurement of contact resistances.

Description

Contact resistance measuring system and method for testing based on voltage-frequency transformation method
Technical field
The present invention relates to a kind of contact resistance measuring system and method for testing.
Background technology
Measuring contact resistance belongs to microresistivity survey.The ultimate principle of such measuring system is a voltammetry, can be subdivided into DC-method, AC method and impulse method etc. again.
In the DC-method, right with the tested contact of known constant current excitation, through amplifying and measuring contact voltage is calculated tested resistance.In order to reach higher resolution, just must improve the enlargement factor that voltage is put amplifier, perhaps improve exciting current, brought problems such as noise increase, poor stability and energy consumption increase thus.
In the AC method, adopt alternating current to encourage tested contact right, and with passive device-transformer as the voltage amplification element, reduced the amplification noise greatly.But introduced new problem: the low-frequency transformer volume and weight is bigger, and the high frequency lower conductor can receive the influence of skin effect, makes the actual measurement resistance become big (relevant with test frequency).
In the impulse method, right with the current impulse excitation contact of certain peak value, can reduce energy consumption greatly, weak point is that this method paired pulses peak value ten minutes is responsive, and the difficult standard of surveying of peak value (especially narrow peak), so accuracy is difficult to improve.
Summary of the invention
The present invention is the problem poor for the data stability that solves the measuring contact resistance method, that accuracy is low, thereby a kind of integration type contact resistance measuring system and measuring method are provided.
Based on the contact resistance measuring system of voltage-frequency transformation method, it comprises controlled constant current source, standard inspection leakage resistance, variable gain voltage amplifier, voltage-frequency converter, voltage follower, AD converter and single-chip microcomputer;
The power output end of controllable current source is connected with an end of UUT; The other end of said UUT is connected with an end of standard inspection leakage resistance; The other end of said standard inspection leakage resistance connects power supply ground;
The variable gain voltage amplifier is gathered the terminal voltage of UUT end; The voltage signal output end of said variable gain voltage amplifier is connected with the voltage signal input end of voltage-frequency converter; The frequency signal output terminal of said voltage-frequency converter is connected with the counter interface end of single-chip microcomputer;
Voltage between voltage follower collection standard inspection leakage resistance and the power supply ground; The voltage signal output end of said voltage follower is connected with the voltage signal input end of AD converter; The AD switching signal output terminal of AD converter is connected with the AD switching signal input end of single-chip microcomputer;
The current controling signal output terminal of single-chip microcomputer is connected with the current controling signal input end of controlled constant current source; The gain control signal output terminal of said single-chip microcomputer is connected with the gain control signal input end of variable gain voltage amplifier.
Based on the measuring contact resistance method based on voltage-frequency transformation method of said apparatus, it is realized by following steps:
Step 1, give UUT, adopt the variable gain voltage amplifier to gather the voltage U at UUT two ends, and the voltage of gathering is amplified through Single-chip Controlling controllable current source output steady current;
Adopt the voltage between voltage follower collection standard inspection leakage resistance and the power supply ground, input to AD converter then, convert digital quantity i into through AD converter x
Step 2, employing voltage-frequency converter are to amplifying the frequency signal of back voltage transitions for being directly proportional with the voltage U at UUT two ends in the step 1; And adopt single-chip microcomputer that this frequency signal is carried out timer counter, obtain the digital quantity U of the terminal voltage U at UUT two ends x, its expression formula is:
U x = u x / T - b kA
In the formula: u xBe count value; T is the gate time interval; A is the gain multiple of variable gain voltage amplifier; K is a pressure/frequency conversion slope; B is a pressure/frequency conversion intercept;
Adopt single-chip microcomputer to read in the digital quantity i that step 1 obtains x, and according to formula:
I x = i x 2 bits · V ref / R ref
Calculate the digital quantity I of exciting current x
In the formula: R RefBe standard inspection leakage resistance resistance; V RefBe the AD converter reference voltage; Bits is the figure place of AD converter;
The digital quantity U of the voltage U at step 3, UUT two ends that step 2 is obtained xDigital quantity I with exciting current x, through formula:
R x=U x/I x
Obtain the resistance value of UUT; Thereby realize the measurement of integration type contact resistance.
The data stability of measuring contact resistance method of the present invention is strong, accuracy is high.
Description of drawings
Fig. 1 is a structural representation of the present invention.
Embodiment
Embodiment one, combination Fig. 1 explain this embodiment; Based on the contact resistance measuring system of voltage-frequency converter technique, it comprises controlled constant current source 1, standard inspection leakage resistance 3, variable gain voltage amplifier 4, voltage-frequency converter 5, voltage follower 6, AD converter 7 and single-chip microcomputer 8;
The power output end of controllable current source 1 is connected with an end of UUT 2; The other end of said UUT 2 is connected with an end of standard inspection leakage resistance 3; The other end of said standard inspection leakage resistance 3 connects power supply ground;
Variable gain voltage amplifier 4 is gathered the terminal voltage at UUT 2 two ends; The voltage signal output end of said variable gain voltage amplifier 4 is connected with the voltage signal input end of voltage-frequency converter 5; The frequency signal output terminal of said voltage-frequency converter 5 is connected with the counter interface end of single-chip microcomputer 8;
Voltage between voltage follower 6 collection standards inspection leakage resistance 3 and the power supply ground; The voltage signal output end of said voltage follower 6 is connected with the voltage signal input end of AD converter 7; The AD switching signal output terminal of AD converter 7 is connected with the AD switching signal input end of single-chip microcomputer 8;
The current controling signal output terminal of single-chip microcomputer 8 is connected with the current controling signal input end of controlled constant current source 1; The gain control signal output terminal of said single-chip microcomputer 8 is connected with the gain control signal input end of variable gain voltage amplifier 4.
Effect of the present invention:
1, voltage-frequency changer has excellent linearity, can provide than the better precision of contact resistance measuring system in the past.
2, voltage-frequency transformation method has very high resolution, is example with conversion chip AD7741, and under the 6MHz clock, its highest resolution can reach 1.042 μ V (gate time is spaced apart 1s), is equivalent to the AD converter of 23bit number of significant digit.And if continue time expand at interval, resolution also can improve, and just can " change resolution with the time ".
3, the raising of resolution also can bring following two benefits: the first, and the voltage amplifier gain need not be provided with very high, has also just reduced the influence of device noise to measurement result; The second, because measuring process is a time period, during this period, measuring system inside and external noise can be made final result more near actual value by smoothly to the influence of measurement result.
Be located in voltage-frequency transformation u xBe count value (realizing) by single-chip microcomputer sheet inside counting device; T is that gate time (is realized by the single-chip microcomputer on-chip timer) at interval; AU xBe conversion input voltage (A is the multiple of the preceding amplifier of conversion); K is a pressure/frequency conversion slope; B is a pressure/frequency conversion intercept.
Then the output frequency f of conversion process can be expressed as f=u x/ T, the transport function of conversion is a linear function, promptly satisfies:
f = u x T = kAU x + b
Concerning conversion chip AD7741, under the 6MHz clock, work as AU xWhen in 0 to 2.5V scope, changing, the scope of f is 0.3 to 2.7MHz.
Embodiment two, this embodiment and embodiment one described contact resistance measuring system based on the voltage-frequency converter technique; It is characterized in that it also comprises LCD MODULE 9, the shows signal input end of said LCD MODULE 9 is connected with the shows signal output terminal of single-chip microcomputer 8.
Embodiment three, this embodiment and embodiment one described contact resistance measuring system based on voltage-frequency transformation method; It is characterized in that it also comprises keyboard 10, the keyboard signal output terminal of said keyboard 10 is connected with the keyboard signal input end of single-chip microcomputer 9.
Embodiment four, based on the measuring contact resistance method based on voltage-frequency transformation method of embodiment one, it is realized by following steps:
Step 1, give UUT 2, adopt variable gain voltage amplifier 4 to gather the voltage U at UUTs 2 two ends, and the voltage of gathering is amplified through single-chip microcomputer 8 control controllable current sources 1 output steady current;
Adopt the voltage between voltage follower 7 collection standards inspection leakage resistance 3 and the power supply ground, input to AD converter 7 then, convert digital quantity i into through AD converter 7 x
Amplify the frequency signal of back voltage transitions in step 2,5 pairs of step 1 of employing voltage-frequency converter for being directly proportional with the voltage U at UUT 2 two ends; And adopt 8 pairs of these frequency signals of single-chip microcomputer to carry out timer counter, obtain the digital quantity U of the terminal voltage U at UUT 2 two ends x, its expression formula is:
U x = u x / T - b kA
In the formula: u xBe count value; T is the gate time interval; A is the gain multiple of variable gain voltage amplifier; K is a pressure/frequency conversion slope; B is a pressure/frequency conversion intercept;
Adopt single-chip microcomputer 8 to read in the digital quantity i that step 1 obtains x, and according to formula:
I x = i x 2 bits · V ref / R ref
Calculate the digital quantity I of exciting current x
In the formula: R RefBe standard inspection leakage resistance resistance; V RefBe the AD converter reference voltage; Bits is the figure place of AD converter;
The digital quantity U of the voltage U at step 3, UUT 2 two ends that step 2 is obtained xDigital quantity I with exciting current x, through formula:
R x=U x/I x
Obtain the resistance value of UUT 2; Thereby realize the measurement of contact resistance.
Adopt the resistance of the UUT 2 of 9 pairs of acquisitions of LCD MODULE to show.
Adopt 10 couples of exciting current I of keyboard to set through UUT 2.
Single-chip microcomputer 8 is the core of whole contact resistance measuring system; The DA converter output end is being controlled the output current (being exciting current I) of controlled constant current source 1 in its sheet; And expanded AD converter 7, LCD MODULE 9 and keyboard 10 through the IO mouth, the input port of sheet inside counting device is connected to voltage-frequency changer 5.
The tested contact of the series relationship of the exciting current process of controlled constant current source 1 output is examined leakage resistance 3 (selecting accurate high-power wire-wound resistor for use) to 2 with standard.
After tested contact is amplified by variable gain voltage amplifier 4 voltage U; Convert a frequency signal that is directly proportional with U into by voltage-frequency changer 5; It is counted in the time interval of a setting by the counter in 8 of the single-chip microcomputers again, thereby obtain the digital quantity U of U x
Be accurate measuring excitation electric current I, at first be converted into voltage signal by standard inspection leakage resistance 3, after voltage follower 6 is isolated, getting into AD converter 7 becomes digital quantity, in the IO of single-chip microcomputer 8 mouth gets into sheet, calculates the digital value I of I again x
Obtained U xAnd I x,, can calculate tested contact to resistance value R through the volt-ampere ratio juris x:
With R xOn LCD 9, show, promptly accomplished the one-shot measurement process.
Keyboard 10 is used to be provided with the size of exciting current I.
The automatic adjustment strategy of gain multiple A and gate time interval T has two (passing through keyboard to set up by the operator) in the measuring process: 1, speed is preferential, and the preferential gain multiple A that regulates regulates counting time interval T then; 2, noise is preferential, and the preferential counting time interval T that regulates regulates gain multiple A then.
Don't work, which kind of regulates strategy, should make reading as far as possible between the full-scale 20%-80% of current range.

Claims (6)

1. based on the contact resistance measuring system of voltage-frequency transformation method, it is characterized in that: it comprises controlled constant current source (1), standard inspection leakage resistance (3), variable gain voltage amplifier (4), voltage-frequency converter (5), voltage follower (6), AD converter (7) and single-chip microcomputer (8);
The power output end of controllable current source (1) is connected with an end of UUT (2); The other end of said UUT (2) is connected with an end of standard inspection leakage resistance (3); The other end of said standard inspection leakage resistance (3) connects power supply ground;
Variable gain voltage amplifier (4) is gathered the terminal voltage at UUT (2) two ends; The voltage signal output end of said variable gain voltage amplifier (4) is connected with the voltage signal input end of voltage-frequency converter (5); The frequency signal output terminal of said voltage-frequency converter (5) is connected with the counter interface end of single-chip microcomputer (8);
Voltage between voltage follower (6) collection standard inspection leakage resistance (3) and the power supply ground; The voltage signal output end of said voltage follower (6) is connected with the voltage signal input end of AD converter (7); The AD switching signal output terminal of AD converter (7) is connected with the AD switching signal input end of single-chip microcomputer (8);
The current controling signal output terminal of single-chip microcomputer (8) is connected with the current controling signal input end of controlled constant current source (1); The gain control signal output terminal of said single-chip microcomputer (8) is connected with the gain control signal input end of variable gain voltage amplifier (4).
2. the contact resistance measuring system based on voltage-frequency transformation method according to claim 1; It is characterized in that it also comprises LCD MODULE (9), the shows signal input end of said LCD MODULE (9) is connected with the shows signal output terminal of single-chip microcomputer (8).
3. the contact resistance measuring system based on voltage-frequency transformation method according to claim 1 is characterized in that it also comprises keyboard (10), and the keyboard signal output terminal of said keyboard (10) is connected with the keyboard signal input end of single-chip microcomputer (9).
4. based on the measuring contact resistance method based on the voltage-frequency converter technique of claim 1, it is characterized in that: it is realized by following steps:
Step 1, give UUT (2), adopt variable gain voltage amplifier (4) to gather the voltage U at UUT (2) two ends, and the voltage of gathering is amplified through single-chip microcomputer (8) control controllable current source (1) output steady current;
Adopt the voltage between voltage follower (7) collection standard inspection leakage resistance (3) and the power supply ground, input to AD converter (7) then, convert digital quantity i into through AD converter (7) x
Step 2, employing voltage-frequency converter (5) are to amplifying the frequency signal of back voltage transitions for being directly proportional with the voltage U at UUT (2) two ends in the step 1; And adopt single-chip microcomputer (8) that this frequency signal is carried out timer counter, obtain the digital quantity U of the terminal voltage U at UUT (2) two ends x, its expression formula is:
U x = u x / T - b kA
In the formula: u xBe count value; T is the gate time interval; A is the gain multiple of variable gain voltage amplifier; K is a pressure/frequency conversion slope; B is a pressure/frequency conversion intercept;
Adopt single-chip microcomputer (8) to read in the digital quantity i that step 1 obtains x, and according to formula:
I x = i x 2 bits · V ref / R ref
Calculate the digital quantity I of exciting current x
In the formula: R RefBe standard inspection leakage resistance resistance; V RefBe the AD converter reference voltage; Bits is the figure place of AD converter;
The digital quantity U of the voltage U at step 3, UUT (2) two ends that step 2 is obtained xDigital quantity I with exciting current x, through formula:
R x=U x/I x
Obtain the resistance value of UUT (2); Thereby realize the measurement of contact resistance.
5. the measuring contact resistance method based on voltage-frequency transformation method according to claim 4 is characterized in that adopting LCD MODULE (9) that the resistance of the UUT (2) of acquisition is shown.
6. the measuring contact resistance method based on voltage-frequency transformation method according to claim 4 is characterized in that adopting keyboard (10) that the exciting current I through UUT (2) is set.
CN2012102183188A 2012-06-28 2012-06-28 Contact resistance measuring system and method based on voltage-frequency conversion method Pending CN102707153A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103149442A (en) * 2013-02-08 2013-06-12 哈尔滨工业大学 Automatic testing device for contact resistor made of electrical contact material
CN103412191A (en) * 2013-08-26 2013-11-27 甘肃农业大学 Minitype resistance measurement system
CN110189790A (en) * 2019-06-18 2019-08-30 北京控制与电子技术研究所 A kind of resistance measurement method based on nonvolatile storage
CN110927465A (en) * 2019-11-26 2020-03-27 深圳供电局有限公司 Direct current resistance measuring circuit and device

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JPS55119066A (en) * 1979-03-09 1980-09-12 Yokogawa Hokushin Electric Corp Measuring device for contact resistance
US5317520A (en) * 1991-07-01 1994-05-31 Moore Industries International Inc. Computerized remote resistance measurement system with fault detection
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CN201281728Y (en) * 2008-09-12 2009-07-29 保定华创电气有限公司 Direct current resistance tester of full-automatic transformer

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103149442A (en) * 2013-02-08 2013-06-12 哈尔滨工业大学 Automatic testing device for contact resistor made of electrical contact material
CN103149442B (en) * 2013-02-08 2015-04-29 哈尔滨工业大学 Automatic testing device for contact resistor made of electrical contact material
CN103412191A (en) * 2013-08-26 2013-11-27 甘肃农业大学 Minitype resistance measurement system
CN103412191B (en) * 2013-08-26 2015-07-01 甘肃农业大学 Minitype resistance measurement system
CN110189790A (en) * 2019-06-18 2019-08-30 北京控制与电子技术研究所 A kind of resistance measurement method based on nonvolatile storage
CN110927465A (en) * 2019-11-26 2020-03-27 深圳供电局有限公司 Direct current resistance measuring circuit and device
CN110927465B (en) * 2019-11-26 2022-09-02 深圳供电局有限公司 Direct current resistance measuring circuit and device

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Application publication date: 20121003