CN106383272B - A kind of small resistance measuring circuit of high-precision - Google Patents
A kind of small resistance measuring circuit of high-precision Download PDFInfo
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- CN106383272B CN106383272B CN201510458300.9A CN201510458300A CN106383272B CN 106383272 B CN106383272 B CN 106383272B CN 201510458300 A CN201510458300 A CN 201510458300A CN 106383272 B CN106383272 B CN 106383272B
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Abstract
The present invention discloses a kind of small resistance measuring circuit of high-precision, which includes: constant-current source circuit, single-ended/calculus of differences amplifying circuit, A/D conversion processing circuit and microprocessor control circuit；Constant-current source circuit provides constant Weak current for measured resistance, and the measurement voltage of millivolt level is generated in measured resistance；Single-ended/calculus of differences amplifying circuit amplifies the voltage of millivolt level, the measurement voltage after obtaining operation amplifier；Measurement voltage after operation amplifier is converted to digital waveform by A/D conversion processing circuit, obtains the measurement voltage of digital waveform；Microprocessor control circuit is filtered the measurement voltage of digital waveform and the resistance value of measured resistance is calculated.Technical solution of the present invention improves the measurement accuracy of small resistance.
Description
Technical field
The present invention relates to circuits.More particularly, to a kind of small resistance measuring circuit of high-precision.
Background technique
In many fields, the survey of high-precision measurement result and high security is required to the measurement of small resistance measurement
Amount process, such as the measurement of priming system resistance value.Priming system resistance value measurement is the important step of missile integration test, and measurement result is
Be related to guided missile whether can normal transmission and flight important parameter.The resistance value of general priming system is smaller, wants to measuring accuracy
Ask higher, and the resistance value measurement of priming system must carry out under secure conditions, it is generally required to measure electric current no more than 10mA.
The minor change of small resistance, signal fluctuation amplitude only have millivolt level, it is difficult to by the not high instrument measurement of precision.
At present in the test of priming system resistance, the small resistance measurement method of two-wire system is mostly used greatly.Using special
With cable system, priming system both ends will be corresponded on bullet and introduce the progress resistance value measurement of professional test instrument.It is surveyed using the resistance of two-wire system
Amount method introduces the cable resistance and contact resistance of measurement cable, has that measurement accuracy is low, reliability is low and Automatic survey
The low disadvantage of degree.
Accordingly, it is desirable to provide a kind of small resistance measuring circuit of high-precision.
Summary of the invention
The purpose of the present invention is to provide a kind of small resistance measuring circuits of high-precision, real under conditions of highly safe
Now small resistance is accurately measured.
In order to achieve the above objectives, the present invention adopts the following technical solutions:
A kind of small resistance measuring circuit of high-precision, the circuit include:
Constant-current source circuit, single-ended/calculus of differences amplifying circuit, A/D conversion processing circuit and microprocessor control circuit；
Constant-current source circuit provides constant Weak current for measured resistance, and the measurement electricity of millivolt level is generated in measured resistance
Pressure；
Single-ended/calculus of differences amplifying circuit amplifies the voltage of millivolt level, the measurement voltage after obtaining operation amplifier；
Measurement voltage after operation amplifier is converted to digital waveform by A/D conversion processing circuit, obtains the survey of digital waveform
Measure voltage；
Microprocessor control circuit is filtered the measurement voltage of digital waveform and measured resistance is calculated
Resistance value.
Preferably, constant-current source circuit includes:
Benchmark source chip, the first triode, the second triode, first resistor, variable resistance and the first relay,
First triode and the second triode generate benchmark source chip supply voltage；The pin 5 of benchmark source chip successively with
First resistor and variable resistance series connection, the measurement electric current of constant output 5mA；Measure 11 He of pin that electric current passes through the first relay
9 are connected to measured resistance, form voltage value at measured resistance both ends；The voltage measurement point at measured resistance both ends passes through first respectively
Pin 2,5 and pin 12,10 output measurement voltage to the single end operational of relay amplify conversion circuit or calculus of differences amplification turns
Change circuit.
Preferably, the Standard resistance range of variable resistance is at 0~100 ohm, and first resistor is for ensuring to fail in variable resistance
In the case where export electric current in safe range.
Preferably, single-ended/calculus of differences amplifying circuit includes:
Second relay, third relay, single end operational amplifier, differential operational amplifier, second resistance, third electricity
Resistance, the 4th resistance, the 5th resistance, the 6th resistance, the 6th resistance, the 7th resistance；
Measurement voltage is just being connected respectively to the pin 5 and pin 10 of the second relay with measurement voltage negative；
Single end operational amplification mode is switched to using the normally-closed contact of the second relay, passes through the pin 1 of the second relay
One end that measurement voltage just arrives second resistance, the pin 3 of the second resistance other end and single end operational amplifier are exported with pin 14
Connection；Operation amplifier multiple is adjusted by second resistance and 3rd resistor, amplification is exported by the pin 6 of single end operational amplifier
Voltage afterwards is as Single-end output analog quantity；
Calculus of differences amplification mode is switched to using the normally opened contact of the second relay, passes through the pipe of the second relay respectively
Foot 2 and the output measurement of pin 13 voltage are just with measurement voltage negative to one end of the 4th resistance and the 6th resistance；4th resistance and
The other end of six resistance is connected respectively to the pin 2 and pin 3 of differential operational amplifier；By the 5th resistance and the 4th resistance,
7th resistance and the 6th resistance adjust operation amplifier multiple, export amplified voltage by the pin 6 of differential operational amplifier
As difference output analog quantity；
The pin 1 and pin 2 of third relay receive Single-end output analog quantity and difference output analog quantity respectively, utilize
The normally opened and normally closed control of three relays switches over, the measurement voltage after exporting operation amplifier.
Preferably, A/D conversion processing circuit includes:
A/D conversion chip, the first isolating chip and the second isolating chip；
The pin 4 of A/D conversion chip receives the measurement voltage after operation amplifier, will by the pin 10 of A/D conversion chip
Voltage value after conversion is exported in the form of square wave to the pin 5 of the second isolating chip；By the first isolating chip and second every
Off-chip piece is isolated by A/D conversion processing circuit with microprocessor control circuit, will by the pin 12 of the second isolating chip
The measurement voltage output of digital waveform is to microprocessor control circuit.
Beneficial effects of the present invention are as follows:
Technical solution of the present invention based on Differential Input operational amplification circuit and high-precision A/D Acquisition Circuit, with
The measurement scheme of four-wire system eliminates the measurement error that measure traverse line generates in measurement circuit, amplifies computing circuit with Differential Input
Influence of the ground circulation to measurement accuracy is reduced, the measurement accuracy of small resistance is improved.
Detailed description of the invention
Specific embodiments of the present invention will be described in further detail with reference to the accompanying drawing.
Fig. 1 shows the small resistance measuring circuit schematic diagram of high-precision.
Fig. 2 shows the constant-current source circuit circuit diagrams in the small resistance measuring circuit of high-precision.
Fig. 3 shows the operational amplification circuit circuit diagram in the small resistance measuring circuit of high-precision.
Fig. 4 shows the A/D conversion circuit circuit diagram in the small resistance measuring circuit of high-precision.
Specific embodiment
In order to illustrate more clearly of the present invention, the present invention is done further below with reference to preferred embodiments and drawings
It is bright.Similar component is indicated in attached drawing with identical appended drawing reference.It will be appreciated by those skilled in the art that institute is specific below
The content of description is illustrative and be not restrictive, and should not be limited the scope of the invention with this.
As shown in Figure 1, the small resistance measuring circuit of high-precision provided in this embodiment, comprising: constant-current source circuit, list
End/calculus of differences amplifying circuit, A/D conversion processing circuit and microprocessor control circuit；
Constant-current source circuit provides high-precision constant Weak current for measured resistance, and millivolt level is generated in measured resistance
Measure voltage, input analog quantity of this voltage as single-ended/calculus of differences amplifying circuit；Single-ended/calculus of differences amplifying circuit pair
Input voltage analog quantity amplifies according to a certain percentage, and amplified voltage is converted to number by A/D conversion processing circuit
Character waveform is transferred to the resistance value that microprocessor control circuit is filtered and measured resistance is calculated by spi bus,
And it is shown by microprocessor control circuit.
As shown in Fig. 2, constant-current source circuit includes: reference source circuit and the relay K1 for controlling Measurement channel,
Wherein, reference source circuit includes:
Benchmark source chip U1, triode Q1, Q2, fixed resistance value resistance R3, variable resistance R4,
Triode Q1 and Q2 generate stable benchmark source chip supply voltage, the pipe of this supply voltage and benchmark source chip U1
Foot 4 connects；The pin 5 of benchmark source chip U1 is connected with resistance R3 and R4, the measurement electric current of constant output 5mA；It wherein can power transformation
The Standard resistance range of R4 is hindered at 0~100 ohm, and fixed resistance value resistance R3 is for ensuring to export in the case where variable resistance R4 fails
Electric current is in safe range；
Measurement electric current is connected to measured resistance Rx by the pin 11 and 9 of relay K1, is formed at the both ends measured resistance Rx
Voltage value.The voltage measurement point V+ and measurement point V- at the both ends measured resistance Rx pass through the pin 2,5 and pin of relay K1 respectively
12,10 outputs give single-ended or calculus of differences to amplify conversion circuit, i.e. measurement voltage in Fig. 2 just with measurement voltage negative.
Constant-current source circuit has temperature-compensating, and environment temperature adaptation range is -40 DEG C -+125 DEG C.Constant-current source circuit output
Electric current is stable, precision is high, does not influence vulnerable to ambient temperature variation bring, provides high-precision electric current for measured resistance.
As shown in figure 3, single-ended/calculus of differences amplifying circuit includes: for switching the relay K2 of single-ended/difference, same to phase
Operational amplification circuit, Differential Input operational amplification circuit, measurement voltage output control circuit；
Wherein
It include single end operational amplifier U2, resistance R7 and R8 with phase operational amplification circuit；
Differential Input operational amplification circuit includes differential operational amplifier U4, resistance R9, R10, R11 and R12；
Measuring voltage output control circuit includes relay K3；
Wherein, input measurement voltage is just being connected to the pin 5 and pin 10 of relay K2 with measurement voltage negative；
Single end operational amplification mode is switched to using the normally-closed contact of relay K2, passes through the pin 1 and pipe of relay K2
Foot 14 exports the input quantity as same phase operational amplification circuit, is connected to one end resistance R7 of same phase operational amplification circuit, resistance
The R7 other end is connect with the pin 3 of single end operational amplifier U2.Operation amplifier multiple is adjusted by resistance R8 and R7, by single-ended
The pin 6 of operational amplifier U2 exports amplified voltage value, i.e. Single-end output analog quantity；
Calculus of differences amplification mode is switched to using the normally opened contact of relay K2, passes through the pin 2 and pipe of relay K2
Foot 13 exports the input quantity as calculus of differences amplifying circuit, is connected to one end of resistance R9 and R11；Resistance R9's and R11 is another
One end is connected to the pin 2 and pin 3 of differential operational amplifier U4；Operation amplifier is adjusted by resistance R10 and R9, R11 and R12
Multiple exports amplified voltage value, i.e. difference output analog quantity by the pin 6 of differential operational amplifier U4；
Single-end output analog quantity and difference output analog quantity are connected respectively to the pin 1 and pin 2 of relay K3, using after
The normally opened and normally closed control of electric appliance K3 switches over, the measurement voltage after exporting operation amplifier.
Same phase operation amplifier circuit is collectively constituted by low-power consumption, the operational amplifier of low noise and resistance, as measurement
The single ended input amplifying circuit of signal；Differential Input operation is collectively constituted by low-power consumption, the operational amplifier of low noise and resistance
Amplifying circuit, as measuring signal Differential Input amplifying circuit.Different amplification is realized by the matching of resistance, improves A/D
Sampling precision, reduce influence of the ground circulation to measurement accuracy, improve measurement accuracy.
As shown in figure 4, A/D conversion processing circuit includes A/D unit and isolation circuit,
Wherein
A/D unit includes A/D conversion chip U6, and isolation circuit includes isolating chip U7 and U8；
Measurement voltage after input quantity operation amplifier is connected to the pin 4 of A/D conversion chip U6, passes through A/D conversion chip
The pin 10 of U6 exports the voltage value after conversion in the form of square wave to the pin 5 of isolating chip U8；By isolating chip U7,
U8 is isolated by A/D conversion processing circuit with microprocessor control circuit, by the pin 12 of isolating chip U8 by digital quantity
Measured value export and handled to microprocessor control circuit.
The signal acquisition circuit being made of 16 high-precision As/D chip, input impedance 26.7k Ω, relative to measured resistance,
The measurement electric current that constant-current source provides will not be split, and ensure that the accuracy of measurement result.A/D is surveyed by high-speed isolated chip
It measures circuit and microprocessor control circuit carries out electrical isolation, reduce influence of other circuits to measurement accuracy.
Microprocessor control circuit is made of devices such as microprocessor, resistance and capacitors.Control is communicated with A/D chip SPI
Timing and process, digital averaging filtering processing and the conversion of measurement result, transmission process are carried out to sampled data.According to choosing
It selects, the selection of the closure, single ended input and Differential Input mode in control measurement circuit.
Obviously, the above embodiment of the present invention be only to clearly illustrate example of the present invention, and not be pair
The restriction of embodiments of the present invention may be used also on the basis of the above description for those of ordinary skill in the art
To make other variations or changes in different ways, all embodiments can not be exhaustive here, it is all to belong to this hair
The obvious changes or variations that bright technical solution is extended out are still in the scope of protection of the present invention.
Claims (4)
1. a kind of small resistance measuring circuit of high-precision, which is characterized in that the circuit includes:
Constant-current source circuit, single-ended/calculus of differences amplifying circuit, A/D conversion processing circuit and microprocessor control circuit；
Constant-current source circuit provides constant Weak current for measured resistance, and the measurement voltage of millivolt level is generated in measured resistance；
Single-ended/calculus of differences amplifying circuit amplifies the measurement voltage of the millivolt level, the measurement after obtaining operation amplifier
Voltage；
Measurement voltage after the operation amplifier is converted to digital waveform by A/D conversion processing circuit, obtains the survey of digital waveform
Measure voltage；
Microprocessor control circuit is filtered the measurement voltage of the digital waveform and measured resistance is calculated
Resistance value；
Single-ended/the calculus of differences amplifying circuit includes:
Second relay, third relay, single end operational amplifier, differential operational amplifier, second resistance, 3rd resistor,
Four resistance, the 5th resistance, the 6th resistance, the 6th resistance, the 7th resistance；
Measurement voltage is just being connected respectively to the pin 5 and pin 10 of the second relay with measurement voltage negative；
Single end operational amplification mode is switched to using the normally-closed contact of the second relay, passes through the pin 1 and pipe of the second relay
The output measurement voltage of foot 14 just arrives one end of second resistance, the connection of pin 3 of the second resistance other end and single end operational amplifier；
Operation amplifier multiple is adjusted by second resistance and 3rd resistor, is exported by the pin 6 of single end operational amplifier amplified
Voltage is as Single-end output analog quantity；
Calculus of differences amplification mode is switched to using the normally opened contact of the second relay, passes through the pin 2 of the second relay respectively
Measurement voltage is exported just with measurement voltage negative to one end of the 4th resistance and the 6th resistance with pin 13；4th resistance and the 6th electricity
The other end of resistance is connected respectively to the pin 2 and pin 3 of differential operational amplifier；Pass through the 5th resistance and the 4th resistance, the 7th
Resistance and the 6th resistance adjust operation amplifier multiple, export amplified voltage conduct by the pin 6 of differential operational amplifier
Difference output analog quantity；
The pin 1 and pin 2 of third relay receive Single-end output analog quantity and difference output analog quantity respectively, using third after
The normally opened and normally closed control of electric appliance switches over, the measurement voltage after exporting operation amplifier.
2. the small resistance measuring circuit of high-precision according to claim 1, which is characterized in that the constant-current source circuit packet
It includes:
Benchmark source chip, the first triode, the second triode, first resistor, variable resistance and the first relay,
First triode and the second triode generate benchmark source chip supply voltage；The pin 5 of benchmark source chip is successively with first
Resistance and variable resistance series connection, the measurement electric current of constant output 5mA；Electric current is measured to connect by the pin 11 and 9 of the first relay
It is connected to measured resistance, forms voltage value at measured resistance both ends；The voltage measurement point at measured resistance both ends pass through respectively first after
Pin 2,5 and pin 12,10 output measurement voltage to the single end operational of electric appliance amplify conversion circuit or calculus of differences amplification conversion
Circuit.
3. the small resistance measuring circuit of high-precision according to claim 2, which is characterized in that
The Standard resistance range of the variable resistance is at 0~100 ohm, and the first resistor is for ensuring to fail in the variable resistance
In the case where export electric current in safe range.
4. the small resistance measuring circuit of high-precision according to claim 1, which is characterized in that the A/D conversion process
Circuit includes:
A/D conversion chip, the first isolating chip and the second isolating chip；
The pin 4 of A/D conversion chip receives the measurement voltage after operation amplifier, will be converted by the pin 10 of A/D conversion chip
Voltage value afterwards is exported in the form of square wave to the pin 5 of the second isolating chip；Pass through the first isolating chip and the second isolated core
Piece is isolated by A/D conversion processing circuit with microprocessor control circuit, will be digital by the pin 12 of the second isolating chip
The measurement voltage output of waveform is to microprocessor control circuit.
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| CN201510458300.9A CN106383272B (en) | 2015-07-30 | 2015-07-30 | A kind of small resistance measuring circuit of high-precision |
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| CN201510458300.9A CN106383272B (en) | 2015-07-30 | 2015-07-30 | A kind of small resistance measuring circuit of high-precision |
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| CN110161313B (en) | 2019-06-19 | 2020-07-24 | 中南大学 | High-precision resistance measurement system and method combining differential method and proportional method |
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| CN113671255A (en) * | 2021-07-30 | 2021-11-19 | 哈尔滨工业大学 | Measuring point configurable integrated missile-borne initiating explosive device resistance measuring system |
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