CN107167678B - Multifunctional analog signal acquisition circuit - Google Patents
Multifunctional analog signal acquisition circuit Download PDFInfo
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- CN107167678B CN107167678B CN201710318191.XA CN201710318191A CN107167678B CN 107167678 B CN107167678 B CN 107167678B CN 201710318191 A CN201710318191 A CN 201710318191A CN 107167678 B CN107167678 B CN 107167678B
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- 238000006243 chemical reaction Methods 0.000 abstract description 9
- 238000005070 sampling Methods 0.000 abstract description 8
- 238000012544 monitoring process Methods 0.000 abstract description 4
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 238000001514 detection method Methods 0.000 description 4
- 230000003321 amplification Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
Abstract
The invention relates to a multifunctional analog signal acquisition circuit, which judges whether a voltage signal output by the analog signal acquisition circuit reaches a peak value of a fixed limit or a normal working voltage range by controlling the opening and closing of a switch; when the voltage signal output by the circuit is in the normal working range, the judgment circuit needs to measure the voltage analog quantity, and the circuit directly outputs the voltage after the conversion of the voltage to be measured. The invention adopts an analog signal acquisition circuit, can meet the requirements of monitoring the current to be measured and the voltage to be measured, does not need to additionally increase the signal acquisition circuit, saves the design cost of the circuit, and simultaneously has the advantages of simple circuit structure, easy production and debugging, high and stable loop sampling precision and smaller offset voltage and temperature drift voltage.
Description
Technical Field
The invention belongs to the technical field of protection, measurement and control of an electric power system, and particularly relates to a multifunctional analog signal acquisition circuit.
Background
The output of the non-electric quantity sensor of the traditional transformer substation is generally 0-5V or 4-20 mA, such as the temperature of a transformer and gas in oil, the grade range of the non-electric quantity analog signal is fixed, only two specifications of current and voltage need to be considered in circuit design, the non-electric quantity analog signal can also be designed to be compatible, and when the non-electric quantity sensor is used, the current sampling is directly converted into the voltage sampling through connecting a current sampling resistor. However, with the progress of the intelligent substation technology, the monitoring range of the non-electric quantity is greatly expanded in the detection of equipment power supply, new energy level, primary equipment detection, lightning arrester and the like, so that the level of the non-electric quantity analog signal has multiple levels, such as 0-600 VDC, 0-300 VDC, 0-48 VDC, 0-5V, -10- +10V, 4-20 mA and-40 mA.
The analog signal acquisition circuit in the prior art generally designs different circuits for different analog quantity ranges to detect, for example, a conversion circuit for measuring voltage analog signals is specially designed, or a conversion circuit for measuring current analog signals is specially designed, and there is no universal analog signal conversion circuit, so that not only is the designed conversion circuit complex, but also the design cost of the conversion circuit is increased.
Disclosure of Invention
The invention aims to provide a multifunctional analog signal acquisition circuit, which is used for solving the problems that the existing conversion circuit for acquiring analog signals cannot be simultaneously suitable for detecting voltage signals and current signals, and detection circuits need to be designed respectively to improve the detection cost.
In order to solve the technical problem, the invention provides a multifunctional analog signal acquisition circuit, which comprises the following solutions:
the first scheme comprises a first branch and a second branch, wherein the ports of the two branches are connected in parallel and used for connecting a signal to be detected, the first branch is provided with a switch and a first resistor in series, the second branch is a resistor voltage division branch, and the voltage division end of the second branch is used for connecting the input end of an operational amplifier.
And on the basis of the first scheme, the second branch circuit is sequentially provided with a second resistor, a third resistor, a fourth resistor and a fifth resistor in series, wherein the two ends of the third resistor and the fourth resistor are voltage division ends.
And in a third scheme, on the basis of the second scheme, the common end of the third resistor and the fourth resistor is grounded.
And in the fourth and fifth schemes, on the basis of the second and third schemes, two ends of the third resistor and the fourth resistor are further connected with a protection element, and the protection element is used for being connected with the input end of the operational amplifier in parallel.
And a sixth scheme and a seventh scheme, wherein on the basis of the fourth scheme and the fifth scheme respectively, the protection element is a voltage stabilizing diode.
And in the eighth scheme, on the basis of the second scheme, the resistance value of the second resistor is equal to that of the fifth resistor, and the resistance value of the third resistor is equal to that of the fourth resistor.
The invention has the beneficial effects that: the voltage signal output by the analog signal acquisition circuit of the invention is judged to reach the peak value of a fixed limit or the normal working voltage range by controlling the opening and closing of the switch, when the switch is opened and the voltage signal output by the circuit reaches the peak value of the fixed limit, the circuit is judged to be the current analog quantity to be measured, then the switch is closed, and the circuit outputs the voltage converted by the current to be measured; when the voltage signal output by the circuit is in the normal working range, the judgment circuit needs to measure the voltage analog quantity, and the circuit directly outputs the voltage after the conversion of the voltage to be measured. The invention adopts an analog signal acquisition circuit, can meet the requirements of monitoring the current to be measured and the voltage to be measured, does not need to additionally increase the signal acquisition circuit, saves the design cost of the circuit, and simultaneously has the advantages of simple circuit structure, easy production and debugging, high and stable loop sampling precision and smaller offset voltage and temperature drift voltage.
Drawings
Fig. 1 is a schematic diagram of a conversion circuit for collecting analog signals according to the present invention.
Detailed Description
The following further describes embodiments of the present invention with reference to the drawings.
The embodiment of the multifunctional analog signal acquisition circuit of the invention comprises the following components:
as shown in fig. 1, the circuit comprises a first branch and a second branch, the first branch is provided with a switch S and a resistor R in series1The second branch circuit string is sequentially provided with a resistor R2、R3、R4And R5Wherein R is5＝R2，R3＝R4Resistance R3And R4Is grounded, and a resistor R3And R4Is also connected with a protection element Z, which is connected in parallel with two input ends of the instrument operational amplifier OP.
The first branch and the second branch are connected in parallel and then connected to a port to be measured for measuring Ain，AinRepresenting the voltage or current to be measured, UoFor converting the voltage to be measured or the current to be measured into a voltage value, RjIs a resistance related to the amplification factor of the operational amplifier OP.
To judge AinWhether the current or the voltage to be measured adopts the following judgment steps:
keeping switch S off, detecting UoVoltage of output when UoAt a fixed limit peak, i.e. UoWhen the voltage exceeds the normal operating range, it is judged that A isinIs the current to be measured; when U is turnedoWhen the voltage of (2) is in the normal operating range, it is judged that A isinAnd recording the voltage value of the voltage to be measured after the voltage to be measured is converted by the circuit.
UoAfter the voltage exceeds the normal operating range, switch S is closed and U is detected againoVoltage of output when detecting U againoWhen the voltage of (A) is within the normal range, A is confirmedinAnd recording the voltage value of the current to be measured after the current to be measured is converted by the circuit.
The principle of such judgment is: when the switch S is turned off, if AinCurrent to be measured output from non-electric-quantity converter, resistance R flowing through current to be measured3And R4The voltage across the protection element Z may exceed the voltage peak across the protection element Z, for example, when the protection element is a zener diode, when the resistor R3And R4When the voltage reaches the trigger condition of the voltage stabilizing diode, the voltage stabilizing diode is kept at the set protection voltage peak value, and U output by the operational amplifier OPoAlso a fixed peak value, which is close to the supply voltage of the operational amplifier OP. Determination of AinAfter the current to be measured flows through the sampling resistor R with small resistance value, the switch S is closed1And a resistance R5、R2Far greater than resistance R1The voltage formed at the parallel input port is in the input range, so that the resistor R3And R4The divided voltage is small, and the voltage stabilizing diode can not be triggered, so that U is enabledoThe output voltage is within the normal operating range.
And closing switch S, and AinDetecting U when voltage to be detected is output by non-electric quantity converteroThe output voltage is R3/(R2+R3)*k*AinOr is represented by R4/(R5+R4)*k*AinWhere k is the amplification factor of the operational amplifier OP of the meter, typically, k is 1+50k/RjDue to the resistance R3Resistance value far less than R2Resistance value, thereby ensuring UoWhen within the normal voltage range, a larger voltage range measurement of the input port can be accomplished.
For example, the protection voltage of the element Z is set to be 12V, the operational amplifier power supply takes 15V, the maximum pin can input 15V, and when the range of the voltage signal to be measured is-100V- +100V, R5＝R2＝95k，R3＝R45 k; the voltage at two ends of the element Z is-5V- + 5V; get Rj＝50k，k＝1+50k/Rj2, so UoThe output range is-10V～+10V。
When the element S is disconnected and the current signal to be measured is 4-20 mA, the current 5mA flows through R2～R5The voltage developed across the element Z is 5mA (R3+ R4) 50V, already far beyond the protective voltage 12V of the element Z, and U is therefore equal to the current, no matter how the current changesoAll output 15V, because 12 x 2 is larger than the operational amplifier power supply, the operational amplifier OP output is not larger than the operational amplifier power supply 15V; when the element S is closed, the current sampling resistor R1 takes 250 ohms, and the maximum voltage across R1 is 20mA 250 (R1/(R2+ R3+ R4+ R5)) -5V, corresponding to UoThe output is 1V.
The invention judges whether the voltage signal output by the analog signal acquisition circuit reaches a fixed peak value or a normal working range by controlling the opening and closing of the switch, judges the current to be measured by the circuit when the voltage signal output by the circuit reaches the fixed peak value, closes the switch, and outputs the voltage converted by the current to be measured by the circuit; when the voltage signal output by the circuit is within the normal working range, the voltage which needs to be measured by the circuit is judged, and the circuit directly outputs the voltage which is converted from the voltage to be measured.
The protective element Z is arranged for absorbing over-high voltage and preventing AinErroneous application of an excessive voltage, R2、R3、R4And R5The divided voltage exceeds the input range of the operational amplifier OP, which results in the damage of the operational amplifier.
The invention adopts an analog signal acquisition circuit, can simultaneously detect the monitoring current and the voltage to be detected, does not need to additionally design a signal acquisition circuit, saves the design cost of the circuit, and simultaneously has the advantages of simple circuit structure, easy production and debugging, high and stable loop sampling precision and smaller offset voltage and temperature drift voltage.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (2)
1. An analog signal acquisition circuit is characterized by comprising a first branch circuit and a second branch circuit, wherein the ports of the two branch circuits are connected in parallel and are used for connecting a signal to be detected, the first branch circuit is provided with a switch and a first resistor in series, the second branch circuit is a resistor voltage division branch circuit, and the voltage division end of the second branch circuit is used for connecting the input end of an operational amplifier;
the second branch circuit is sequentially provided with a second resistor, a third resistor, a fourth resistor and a fifth resistor in series, wherein two ends of the third resistor and the fourth resistor are voltage division ends;
the common end of the third resistor and the fourth resistor is grounded; two ends of the third resistor and the fourth resistor are also connected with a protection element, and the protection element is used for being connected with the input end of the operational amplifier in parallel;
the protection element is a voltage stabilizing diode.
2. The analog signal acquisition circuit of claim 1, wherein the second resistor has a resistance equal to that of the fifth resistor, and the third resistor has a resistance equal to that of the fourth resistor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201710318191.XA CN107167678B (en) | 2017-05-08 | 2017-05-08 | Multifunctional analog signal acquisition circuit |
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| CN201710318191.XA CN107167678B (en) | 2017-05-08 | 2017-05-08 | Multifunctional analog signal acquisition circuit |
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| CN107167678A CN107167678A (en) | 2017-09-15 |
| CN107167678B true CN107167678B (en) | 2020-11-17 |
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| JP7468266B2 (en) | 2020-09-16 | 2024-04-16 | オムロン株式会社 | Voltage Detector |
| CN112147399B (en) * | 2020-09-25 | 2024-02-23 | 南京林洋电力科技有限公司 | Analog quantity acquisition module and automatic type identification circuit thereof |
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| CN101769957A (en) * | 2010-02-02 | 2010-07-07 | 株洲南车时代电气股份有限公司 | Automatic switching circuit for voltage and current measurement and method thereof |
| CN105137292A (en) * | 2015-09-22 | 2015-12-09 | 国家电网公司 | Direct-current signal intelligent acquiring device used for high-voltage cable fault positioning |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101476903A (en) * | 2009-02-17 | 2009-07-08 | 北京市农林科学院 | General-purpose interface collection system of sensor |
| CN201583826U (en) * | 2009-09-23 | 2010-09-15 | 伊玛精密电子（苏州）有限公司 | ASI analog quantity acquisition module |
| CN201845047U (en) * | 2010-10-27 | 2011-05-25 | 金培庸 | Indicator for respectively displaying two different voltage classes on DC (direct current) circuit |
| CN104658385A (en) * | 2013-11-20 | 2015-05-27 | 南京化工职业技术学院 | Demonstration instrument table for simulating electronic experiment test |
| CN104408006A (en) * | 2014-11-12 | 2015-03-11 | 重庆市上泽机电有限公司 | Analog quantity output module |
| CN104410422A (en) * | 2014-11-18 | 2015-03-11 | 重庆市金泽鑫科技有限公司 | Analog output module |
| CN204177856U (en) * | 2014-11-24 | 2015-02-25 | 重庆电讯职业学院 | Auto repair detects with examination lamp |
| CN205693341U (en) * | 2016-06-03 | 2016-11-16 | 山东大学 | High pressure SIC device crosses the testing circuit of stream, protection circuit and detection and protection circuit |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101769957A (en) * | 2010-02-02 | 2010-07-07 | 株洲南车时代电气股份有限公司 | Automatic switching circuit for voltage and current measurement and method thereof |
| CN105137292A (en) * | 2015-09-22 | 2015-12-09 | 国家电网公司 | Direct-current signal intelligent acquiring device used for high-voltage cable fault positioning |
Non-Patent Citations (1)
| Title |
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