CN112213548A - DC small signal measuring device and method - Google Patents
DC small signal measuring device and method Download PDFInfo
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- CN112213548A CN112213548A CN202011041779.3A CN202011041779A CN112213548A CN 112213548 A CN112213548 A CN 112213548A CN 202011041779 A CN202011041779 A CN 202011041779A CN 112213548 A CN112213548 A CN 112213548A
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- 238000000034 method Methods 0.000 title claims abstract description 17
- 230000010354 integration Effects 0.000 claims abstract description 33
- 239000003990 capacitor Substances 0.000 claims abstract description 30
- 238000005259 measurement Methods 0.000 claims abstract description 14
- 238000001514 detection method Methods 0.000 claims description 21
- 238000000691 measurement method Methods 0.000 abstract description 6
- 238000010586 diagram Methods 0.000 description 4
- 238000005070 sampling Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
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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
- G01R19/14—Indicating direction of current; Indicating polarity of voltage
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/30—Structural combination of electric measuring instruments with basic electronic circuits, e.g. with amplifier
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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
- G01R19/0084—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring voltage only
Abstract
The invention relates to a direct-current voltage small-signal measuring device and a corresponding measuring method, because the charging integration time of direct-current voltage small-signal input voltage on a capacitor is integral multiple of a power frequency period, and the integrated voltage of power frequency interference on the capacitor is 0 in the whole power frequency period, the influence of the power frequency interference on a direct-current voltage signal can be eliminated. The measurement method provided by the invention can effectively inhibit power frequency interference, and the method only needs zero calibration, and can effectively eliminate measurement errors caused by gain errors of a data acquisition system.
Description
Technical Field
The invention relates to the technical field of direct-current voltage small-signal measurement, in particular to a direct-current small-signal measurement device and method.
Background
The state monitoring of the substation equipment needs to acquire information such as ambient temperature and humidity, and output signals of some types of temperature and humidity sensors are direct-current voltage small signals, and the voltage ranges of common direct-current voltage small signals are +/-5V and +/-10V. Because the power frequency interference of the transformer substation is strong or the wire harness connecting the sensor to the data acquisition system is long, the power frequency interference can be coupled in the direct-current voltage signal received by the data acquisition system, and the power frequency interference can even submerge the direct-current voltage signal. For accurately sampling the small direct-current voltage signals, power frequency interference needs to be suppressed.
Disclosure of Invention
Based on the above situation in the prior art, an object of the present invention is to provide a dc voltage small signal measurement apparatus and a corresponding measurement method, which can effectively suppress power frequency interference, and which only needs zero calibration and can effectively eliminate measurement errors caused by gain errors of a data acquisition system.
To achieve the above object, according to one aspect of the present invention, there is provided a small direct current signal measuring apparatus including an integrating circuit, a control circuit, and a switching circuit, wherein,
the switching circuit is connected with the input end of the integrating circuit and controls the input end of the integrating circuit to switch so as to respectively input the direct current small signal into the voltage ViInternal negative precision reference-VrefOr internal positive precision reference + VrefThe integration circuit is connected with the capacitor and integrates or reversely integrates the capacitor in the integration circuit;
the control circuit is respectively connected with the integrating circuit and the switching circuit and used for outputting voltage V to the integrating circuitoCarrying out polarity detection and controlling the switching circuit according to a detection result;
the control circuit is further based on an integration duration and an internal negative precision reference-VrefOr internal positive precision reference + VrefCalculating DC small signal input voltage ViAnd determines the input voltage ViOf (c) is used.
Further, the switching circuit inputs a DC small signal into the voltage ViAnd the time length for integrating the capacitor in the integrating circuit is n power frequency periods T, wherein n is 1, 2 and 3 … ….
Further, the controlling circuit controls the switching circuit according to the polarity detection result, including: if the output voltage V isoPositive polarity, the input voltage ViFor negative polarity, the internal negative precision reference-VrefIs connected to the input of the integrating circuit if the output voltage VoNegative polarity, then the input voltage ViFor positive polarity, the internal positive precision reference + VrefIs connected to the input of the integrating circuit.
Further, the switching circuit couples the internal negative precision reference-VrefOr internal positive precision reference + VrefConnected with the integrating circuit to integrate the powerThe capacitance in the circuit is reversely integrated until the output voltage VoIs 0 and the duration of the inverse integration is t.
Further, the control circuit calculates the DC small-signal input voltage V according to the following formulaiThe value of (c):
furthermore, the integrating circuit comprises an operational amplifier, a capacitor and a resistor, wherein one end of the resistor is connected with the inverting input end of the operational amplifier and is connected with the output end of the operational amplifier through the capacitor, and the other end of the resistor is connected with the switching circuit.
According to another aspect of the present invention, there is provided a dc small signal measuring method, including the steps of:
s1, inputting the DC small signal into the voltage ViThe power supply circuit is connected to the input end of an integrating circuit, and integrates the capacitance of the integrating circuit for n power frequency periods T, wherein n is 1, 2 and 3 … …;
s2, output voltage VoAnd detecting the polarity of the internal negative precision reference-V according to the polarity detection resultrefOr internal positive precision reference + VrefAn input terminal connected to the integrating circuit;
s3, the internal negative precision reference-VrefOr internal positive precision reference + VrefIntegrating the capacitance reversely and starting timing until the output voltage VoIs 0, the timing is t;
s4, according to the integration time, the inverse integration time and the internal negative precision reference-VrefOr internal positive precision reference + VrefCalculating the DC small signal input voltage ViAnd determines the input voltage ViOf (c) is used.
Further, an internal negative precision reference-V is set according to the result of polarity detectionrefOr internal positive precision reference + VrefAn input terminal connected to the integration circuit, including if the output power isPressure VoPositive polarity, the input voltage ViConnecting said input to an internal negative precision reference-V for negative polarityrefIf said output voltage V isoNegative polarity, then the input voltage ViFor positive polarity, connect the input to an internal positive precision reference + Vref。
Further, the DC small signal input voltage V is calculated according to the following formulaiThe value of (c):
furthermore, the integrating circuit comprises an operational amplifier, a capacitor and a resistor, wherein one end of the resistor is connected with the inverting input end of the operational amplifier and is connected with the output end of the operational amplifier through the capacitor, and the other end of the resistor is connected with the switching circuit.
In summary, the present invention provides a dc voltage small signal measurement apparatus and a corresponding measurement method, because the integration time of charging the capacitor by the dc voltage small signal input voltage is an integral multiple of the power frequency period, and the integrated voltage of the power frequency interference on the capacitor is 0 in the whole power frequency period, the influence of the power frequency interference on the dc voltage signal can be eliminated. The measurement method provided by the invention can effectively inhibit power frequency interference, and the method only needs zero calibration, and can effectively eliminate measurement errors caused by gain errors of a data acquisition system. Compared with the prior art, the invention has the following beneficial technical effects:
(1) the power frequency interference can be effectively inhibited, and accurate measurement can be realized even if the direct-current voltage small signal is submerged by the power frequency interference;
(2) only the zero point needs to be calibrated, and full-range calibration is not needed, so that the complexity of the measurement process is reduced, and the measurement error caused by the gain error of the data acquisition system can be effectively eliminated.
Drawings
FIG. 1 is a block diagram of the overall structure of the DC voltage small signal measuring device of the present invention;
FIG. 2 is a schematic circuit diagram of the DC voltage small signal measuring device of the present invention;
FIG. 3 is a flow chart of the DC voltage small signal measuring method of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
The technical solution of the present invention will be described in detail below with reference to the accompanying drawings. According to an embodiment of the present invention, there is provided a dc small signal measuring apparatus, and fig. 1 is a block diagram of an overall structure of the measuring apparatus, as shown in fig. 1, the measuring apparatus includes: integrating circuit, control circuit and switching circuit.
The switching circuit is connected with the input end of the integrating circuit and controls the input end of the integrating circuit to switch so as to respectively input the direct current small signal into the voltage ViInternal negative precision reference-VrefOr internal positive precision reference + VrefAnd the capacitor is connected with the integrating circuit and integrates or inversely integrates the capacitor in the integrating circuit. Fig. 2 shows a schematic circuit diagram of the dc small-signal measuring apparatus, and as shown in fig. 2, the integrating circuit may include an operational amplifier, a capacitor, and a resistor, one end of the resistor is connected to the inverting input terminal of the operational amplifier and connected to the output terminal of the operational amplifier through the capacitor, and the other end of the resistor is connected to the switching circuit.
When the switching circuit inputs a DC small signal into the voltage ViWhen the circuit is connected with the integrating circuit, the time length for integrating the capacitor in the integrating circuit is n power frequency periods T, wherein n is 1, 2 and 3 … …. When the switching circuit switches the internal negative precision reference-VrefOr internal positive precision reference + VrefWhen connected with the integrating circuit, the integrating circuit is used for integrating electricityThe capacitance in the circuit is reversely integrated until the output voltage VoIs 0 and the duration of the inverse integration is t.
According to some embodiments, the switching circuit may be implemented by controlling the switch K by connecting the input of said integrating circuit to the dc small signal input voltage ViInternal negative precision reference-VrefAnd an internal positive precision reference + VrefBy controlling the switch K connection, and by switching the control switch K, the voltage inputs can be connected to the input end of the integrating circuit to carry out charging integration on the integrating circuit.
The control circuit is respectively connected with the integrating circuit and the switching circuit and used for outputting voltage V to the integrating circuitoPolarity detection is carried out, the switching circuit is controlled according to the detection result, and the control circuit can also carry out output voltage V of the integrating circuitoPerforming zero value detection and simultaneous timing, and applying negative precision reference-V in the interiorrefOr internal positive precision reference + VrefIn the process of reversely integrating the capacitor in the integrating circuit, the control circuit starts to time and simultaneously performs zero value detection, and when the output voltage V is detectedoAt 0, the timing of the control circuit is ended, so that the time length t of the inverse integration can be obtained.
Specifically, the control circuit controls the switching circuit according to the polarity detection result, and includes: if the output voltage V isoIf the voltage is positive, the input voltage V is determinediFor negative polarity, the internal negative precision reference-VrefIs connected to the input of the integrating circuit if the output voltage VoIf it is negative, the input voltage V is determinediFor positive polarity, the internal positive precision reference + VrefIs connected to the input of the integrating circuit. The control circuit is further based on an integration duration and an internal negative precision reference-VrefOr internal positive precision reference + VrefCalculating DC small signal input voltage ViCan calculate the DC small-signal input voltage V according to the following formulaiThe value of (c):
according to some embodiments, the control circuit may be implemented by an MCU, the MCU is connected to the output end of the integration circuit, and performs polarity detection and zero value detection on the output voltage of the integration circuit, and may time the integration and inverse integration time by using a timer in the MCU. The MCU is also connected to the control end of the control switch K and used for carrying out switching control on the control switch K according to the detection result.
According to another embodiment of the present invention, there is provided a dc voltage small signal measurement method, a flowchart of which is shown in fig. 3, including the steps of:
s1, inputting the DC small signal into the voltage ViAnd the circuit is connected to the input end of the integrating circuit, and integrates the capacitance in the integrating circuit for n power frequency periods T, wherein n is 1, 2 and 3 … …. Generally, the longer the integration time, the stronger the noise suppression capability, but the longer the measurement time is required, so that the integration time can be determined according to actual requirements. The integrating circuit may adopt a circuit having the following structure: the circuit comprises an operational amplifier, a capacitor and a resistor, wherein one end of the resistor is connected with the inverting input end of the operational amplifier and is connected with the output end of the operational amplifier through the capacitor, and the other end of the resistor is connected with the switching circuit.
S2, after the integration is finished, the output voltage V is adjustedoAnd detecting the polarity of the internal negative precision reference-V according to the polarity detection resultrefOr internal positive precision reference + VrefIs connected to the input of the integrating circuit. Wherein the internal negative precision reference-V is determined according to the polarity detection resultrefOr internal positive precision reference + VrefIs connected to the input of the integrating circuit, including if the output voltage V isoPositive polarity, the input voltage V is determinediConnecting said input to an internal negative precision reference-V for negative polarityrefIf said output voltage V isoNegative polarity, then the input voltage ViIs a positive electrodeConnecting the input to an internal positive precision reference + Vref。
S3, the internal negative precision reference-VrefOr internal positive precision reference + VrefReversely integrating and timing the capacitor, and simultaneously, timing by a timer until the output voltage V is reachedoIs 0, and the timing is t.
S4, according to the integration time, the inverse integration time and the internal negative precision reference-VrefOr internal positive precision reference + VrefCalculating the DC small signal input voltage ViThe value of (d), in particular, the dc small-signal input voltage V can be calculated according to the following formulaiThe value of (c):
in summary, the present invention relates to a dc voltage small signal measurement apparatus and a corresponding measurement method, because the integration time of charging the capacitor with the dc voltage small signal input voltage is an integral multiple of the power frequency period, and the integrated voltage of the power frequency interference on the capacitor is 0 in the whole power frequency period, the influence of the power frequency interference on the dc voltage small signal measurement can be eliminated. In the reverse integration process, when the zero value detection circuit detects that the output voltage is 0, the MCU timer finishes timing. The sampling precision of the system can be ensured only by calibrating the zero point and improving the timing precision of the timer, and the calibration in a full sampling voltage range is not needed. The measuring method provided by the invention can effectively inhibit power frequency interference and effectively eliminate the measuring error caused by the gain error of the data acquisition system.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.
Claims (10)
1. The direct current small signal measuring device is characterized by comprising an integrating circuit, a control circuit and a switching circuit, wherein,
the switching circuit is connected with the input end of the integrating circuit and controls the input end of the integrating circuit to switch so as to respectively input the direct current small signal into the voltage ViInternal negative precision reference-VrefOr internal positive precision reference + VrefThe integration circuit is connected with the capacitor and integrates or reversely integrates the capacitor in the integration circuit;
the control circuit is respectively connected with the integrating circuit and the switching circuit and used for outputting voltage V to the integrating circuitoCarrying out polarity detection and controlling the switching circuit according to a detection result;
the control circuit is further based on an integration duration and an internal negative precision reference-VrefOr internal positive precision reference + VrefCalculating DC small signal input voltage ViAnd determines the input voltage ViOf (c) is used.
2. The DC small signal measuring device according to claim 1, wherein the switching circuit inputs a DC small signal into the voltage ViAnd the time length for integrating the capacitor in the integrating circuit is n power frequency periods T, wherein n is 1, 2 and 3 … ….
3. The dc small-signal measuring device according to claim 2, wherein the control circuit controls the switching circuit according to the polarity detection result, and includes: if the output voltage V isoPositive polarity, the input voltage ViFor negative polarity, the internal negative precision reference-VrefIs connected to the input of the integrating circuit if the output voltage VoNegative polarity, then the input voltage ViFor positive polarity, the internal positive precision reference + VrefAn input connected to the integrating circuitAnd (4) an end.
4. The DC small signal measurement device according to claim 3, wherein the switching circuit couples the internal negative precision reference-VrefOr internal positive precision reference + VrefConnected with the integration circuit, and performing reverse integration on the capacitance in the integration circuit until the output voltage VoIs 0 and the duration of the inverse integration is t.
5. The DC small signal measuring device according to claim 4, wherein the control circuit calculates the DC small signal input voltage V according to the following formulaiThe value of (c):
6. the small direct current signal measuring device according to claim 1, wherein the integrating circuit includes an operational amplifier, a capacitor, and a resistor, one end of the resistor is connected to the inverting input terminal of the operational amplifier and connected to the output terminal of the operational amplifier through the capacitor, and the other end of the resistor is connected to the switching circuit.
7. A DC small signal measuring method is characterized by comprising the following steps:
s1, inputting the DC small signal into the voltage ViThe circuit is connected to the input end of an integrating circuit, and integrates n power frequency periods T into a capacitor in the integrating circuit, wherein n is 1, 2 and 3 … …;
s2, output voltage VoAnd detecting the polarity of the internal negative precision reference-V according to the polarity detection resultrefOr internal positive precision reference + VrefAn input terminal connected to the integrating circuit;
s3, the internal negative precision reference-VrefOr internal positive precision reference + VrefIntegrating the capacitance reverselyAnd starts to time until the output voltage VoIs 0, the timing is t;
s4, according to the integration time, the inverse integration time and the internal negative precision reference-VrefOr internal positive precision reference + VrefCalculating the DC small signal input voltage ViAnd determines the input voltage ViOf (c) is used.
8. The small direct current signal measuring method according to claim 7, wherein an internal negative precision reference-V is set according to the result of polarity detectionrefOr internal positive precision reference + VrefIs connected to the input of the integrating circuit, including if the output voltage V isoPositive polarity, the input voltage ViConnecting said input to an internal negative precision reference-V for negative polarityrefIf said output voltage V isoNegative polarity, then the input voltage ViFor positive polarity, connect the input to an internal positive precision reference + Vref。
9. The method according to claim 8, wherein the DC small-signal input voltage V is calculated according to the following formulaiThe value of (c):
10. the small direct current signal measuring method according to claim 7, wherein the integrating circuit includes an operational amplifier, a capacitor, and a resistor, one end of the resistor is connected to the inverting input terminal of the operational amplifier and connected to the output terminal of the operational amplifier through the capacitor, and the other end of the resistor is connected to the switching circuit.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05219749A (en) * | 1992-01-31 | 1993-08-27 | Nippon Telegr & Teleph Corp <Ntt> | Switching power supply |
| CN1601910A (en) * | 2004-10-18 | 2005-03-30 | 大连大学 | So H2 line-frequency synchronous reverse integration A/D converter |
| JP2006317425A (en) * | 2005-04-12 | 2006-11-24 | Fuji Electric Systems Co Ltd | Alternating current voltage detection system for power conversion circuit |
| CN103091561A (en) * | 2012-12-26 | 2013-05-08 | 常州同惠电子股份有限公司 | Device obtaining direct current signals from alternative current and direct current superposition signals and method thereof |
| CN103957010A (en) * | 2014-05-20 | 2014-07-30 | 石家庄数英仪器有限公司 | High-precision analog-to-digital converter and analog-to-digital conversion method |
-
2020
- 2020-09-28 CN CN202011041779.3A patent/CN112213548A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05219749A (en) * | 1992-01-31 | 1993-08-27 | Nippon Telegr & Teleph Corp <Ntt> | Switching power supply |
| CN1601910A (en) * | 2004-10-18 | 2005-03-30 | 大连大学 | So H2 line-frequency synchronous reverse integration A/D converter |
| JP2006317425A (en) * | 2005-04-12 | 2006-11-24 | Fuji Electric Systems Co Ltd | Alternating current voltage detection system for power conversion circuit |
| CN103091561A (en) * | 2012-12-26 | 2013-05-08 | 常州同惠电子股份有限公司 | Device obtaining direct current signals from alternative current and direct current superposition signals and method thereof |
| CN103957010A (en) * | 2014-05-20 | 2014-07-30 | 石家庄数英仪器有限公司 | High-precision analog-to-digital converter and analog-to-digital conversion method |
Non-Patent Citations (1)
| Title |
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| 王海燕;高之圣;: "积分式直流数字电压表的设计", 电子制作, no. 21, pages 6 - 7 * |
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