CN106556729A - A kind of current measuring device - Google Patents
A kind of current measuring device Download PDFInfo
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- CN106556729A CN106556729A CN201510624132.6A CN201510624132A CN106556729A CN 106556729 A CN106556729 A CN 106556729A CN 201510624132 A CN201510624132 A CN 201510624132A CN 106556729 A CN106556729 A CN 106556729A
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- 230000006698 induction Effects 0.000 claims abstract description 72
- 238000012545 processing Methods 0.000 claims abstract description 26
- 239000003990 capacitor Substances 0.000 claims description 90
- 238000001914 filtration Methods 0.000 claims description 37
- 230000001629 suppression Effects 0.000 claims description 31
- 230000001052 transient effect Effects 0.000 claims description 31
- 238000012544 monitoring process Methods 0.000 claims description 19
- 230000003321 amplification Effects 0.000 claims description 18
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 18
- 230000000694 effects Effects 0.000 claims description 12
- 238000005259 measurement Methods 0.000 claims description 8
- 230000005540 biological transmission Effects 0.000 claims description 4
- 230000000903 blocking effect Effects 0.000 claims description 4
- 230000001939 inductive effect Effects 0.000 claims description 4
- 230000005355 Hall effect Effects 0.000 claims description 3
- 239000000758 substrate Substances 0.000 claims description 3
- 230000005641 tunneling Effects 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 11
- 238000013461 design Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 238000010248 power generation Methods 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
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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Abstract
The present invention provides a kind of current measuring device, including magnetic core, magnetic induction unit and processing unit, and two opening air gaps are symmetrically provided with magnetic core, each at each opening air gap to arrange magnetic induction unit described in；The processing unit includes two one-level amplifying units, two grades of amplifying units and filter unit, wherein, one-level amplifying unit described in the outfan of each magnetic induction unit correspondence one, the one-level amplifying unit is for switching to single-ended signal by the induced signal；Two grades of amplifying units are amplified signal for suing for peace and being amplified to obtain to two single-ended signals；The filter element is for from the signal amplified in frequency range needed for signal acquisition.The current measuring device has the advantages that high precision, bandwidth, reliability are high, overload capacity is strong, strong antijamming capability.
Description
Technical Field
The invention relates to a measuring technology, in particular to a current measuring device.
Background
In electrical equipment in the fields of smart power grids, wind power generation, metallurgy, chemical industry and the like, current sensors are often required to continuously measure the current in work. Furthermore, with the continuous improvement of the related art in recent years, the current sensor is also continuously improved and perfected in terms of technology, design, and performance.
The current sensor comprises a magnetic induction unit and a processing unit, wherein the magnetic induction unit is used for inducing a magnetic field generated by current flowing through a current measured lead and outputting an induction signal (generally, a voltage signal), and the processing unit is used for processing the induction signal to obtain a current value of the measured lead. The design mode of the processing unit corresponds to the output signals of the magnetic induction units, and the output signals of different magnetic induction units correspond to different processing units; and the processing power of the processing unit is one of the important factors affecting the performance of the current sensor.
At present, more current sensors are used as Hall current sensors, and people think that the open-loop Hall current sensors have low precision and narrow bandwidth, and the performance of the closed-loop Hall current sensors is superior to that of the open-loop Hall current sensors.
Disclosure of Invention
The invention provides a current measuring device which adopts an open-loop form and has the advantages of high precision, wide frequency band and strong anti-interference capability.
To this end, the invention provides a current measuring device comprising a magnetic core, a magnetic induction unit and a processing unit, wherein,
the magnetic core is used for gathering a magnetic field generated by current flowing through the lead, and an open air gap is arranged on the magnetic core;
the magnetic induction unit is arranged in the open air gap and used for inducing a magnetic field and outputting an induction signal;
the input end of the processing unit is electrically connected with the output end of the magnetic induction unit and is used for processing the induction signal and obtaining the current value flowing through the measured lead;
the magnetic core is symmetrically provided with two open air gaps, and each open air gap is provided with one magnetic induction unit;
the processing unit comprises two primary amplifying units, a secondary amplifying unit and a filtering unit, wherein the output end of each magnetic induction unit corresponds to one primary amplifying unit, and the primary amplifying units are used for converting the induction signals into single-ended signals; the two-stage amplifying unit is used for summing and amplifying the two single-ended signals to obtain an amplified signal; the filtering unit is used for obtaining signals in a required frequency band from the amplified signals.
Wherein each of the first-stage amplifying units includes a low noise amplifier and a first resistor, wherein,
the input end of each low-noise amplifier is electrically connected with the output end of one magnetic induction unit, and the output end of each low-noise amplifier is electrically connected with the input end of the secondary amplification unit;
and two ends of the first resistor are correspondingly and electrically connected with two gain ends of the low-noise amplifier.
Each primary amplifying unit comprises a first amplifier, a second amplifier, a third amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor, wherein the high-voltage input end of the first amplifier is electrically connected with the output end of the magnetic induction unit;
the first pole of the first resistor is electrically connected with the output end of the first amplifier, and the second pole of the first resistor is electrically connected with the high-voltage input end of the third amplifier;
the first pole of the second resistor is electrically connected with the low-voltage input end of the first amplifier, and the second pole of the second resistor is electrically connected with the output end of the first amplifier;
the first pole of the third resistor is electrically connected with the low-voltage input end of the first amplifier, and the second pole of the third resistor is electrically connected with the output end of the second amplifier;
the first pole of the fourth resistor is electrically connected with the low-voltage input end of the second amplifier, and the second pole of the fourth resistor is electrically connected with the output end of the second amplifier;
the first pole of the fifth resistor is electrically connected with the output end of the second amplifier, and the second pole of the fifth resistor is electrically connected with the low-voltage input end of the third amplifier.
Each primary amplifying unit comprises a first amplifier, a second amplifier, a third amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a first capacitor, wherein the high-voltage input end of the first amplifier is electrically connected with the output end of the magnetic induction unit;
the first pole of the first resistor is electrically connected with the output end of the first amplifier, and the second pole of the first resistor is electrically connected with the high-voltage input end of the third amplifier;
the first pole of the second resistor is electrically connected with the low-voltage input end of the first amplifier, and the second pole of the second resistor is electrically connected with the output end of the first amplifier;
the first pole of the third resistor is electrically connected with the low-voltage input end of the first amplifier, and the second pole of the third resistor is electrically connected with the first end of the first capacitor;
the first pole of the fourth resistor is electrically connected with the low-voltage input end of the second amplifier, and the second pole of the fourth resistor is electrically connected with the output end of the second amplifier;
the first pole of the fifth resistor is electrically connected with the output end of the second amplifier, and the second pole of the fifth resistor is electrically connected with the low-voltage input end of the third amplifier;
the first pole of the first capacitor is electrically connected with the second pole of the third resistor, and the second pole of the first capacitor is electrically connected with the high-voltage input end of the second amplifier.
The second-stage amplification unit comprises a first operational amplifier, a second resistor, a third resistor and a fourth resistor, wherein a first pole of the second resistor is electrically connected with an output end of the low-noise amplifier, and a second pole of the second resistor is electrically connected with a low-voltage input end of the first operational amplifier; the first pole of the third resistor is electrically connected with the output end of the other low-noise amplifier, and the second pole of the third resistor is electrically connected with the low-voltage input end of the first operational amplifier; a first pole of the fourth resistor is electrically connected with the low-voltage input end of the first operational amplifier, and a second pole of the fourth resistor is electrically connected with the output end of the first operational amplifier; the high-voltage input end of the first operational amplifier is grounded.
The second-stage amplification unit comprises a first capacitor, a first pole of the first capacitor is electrically connected with the low-voltage input end of the first operational amplifier, and a second pole of the first capacitor is electrically connected with the output end of the first operational amplifier.
And a blocking capacitor is respectively arranged between the output end of the low noise amplifier and the first pole of the second resistor and between the output end of the low noise amplifier and the first pole of the third resistor.
The filtering unit comprises a filtering operational amplifier, a fifth resistor, a sixth resistor, a second capacitor and a third capacitor;
a first pole of the fifth resistor is electrically connected with the output end of the first operational amplifier, and a second pole of the fifth resistor is electrically connected with a first pole of the sixth resistor;
the second pole of the sixth resistor is electrically connected with the high-voltage input end of the filtering operational amplifier;
the first pole of the second capacitor is electrically connected with the second pole of the fifth resistor and the first pole of the sixth resistor, and the second pole of the second capacitor is electrically connected with the output end of the filtering operational amplifier;
the first pole of the third capacitor is electrically connected with the high-voltage input end of the filtering operational amplifier, and the second pole of the third capacitor is grounded;
and the low-voltage input end of the filtering operational amplifier is electrically connected with the output end of the filtering operational amplifier.
A transient suppression diode is arranged at the input end of each low-noise amplifier, a first pole of the transient suppression diode is electrically connected with the input end of the low-noise amplifier, and a second pole of the transient suppression diode is grounded;
and a transient suppression diode is arranged at the output end of the filtering operational amplifier, the first pole of the transient suppression diode is electrically connected with the output end of the filtering operational amplifier, and the second pole of the transient suppression diode is grounded.
The magnetic induction units comprise a substrate and a plurality of groups of magnetic induction units, the plurality of groups of magnetic induction units are electrically connected to form a Wheatstone bridge, and two output ends of the Wheatstone bridge are output ends of the magnetic induction units;
the current measuring device comprises a current source, the current source is used for providing electric energy for the Wheatstone bridge, and the current source comprises a constant current source, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a sixth capacitor, a seventh capacitor, an eighth capacitor and a ninth capacitor; the constant current source comprises an input end, an output end and a setting end;
a first pole of the seventh resistor is electrically connected with the output end of the constant current source, and a second pole of the seventh resistor is electrically connected with the output end of the constant current source;
a first pole of the eighth resistor is electrically connected with the setting end of the constant current source, and a second pole of the eighth resistor is electrically connected with the output end of the constant current source;
the first pole of the ninth resistor is electrically connected with the input end of the constant current source, and the second pole of the ninth resistor is electrically connected with the first pole of the ninth capacitor;
a first pole of the tenth resistor is electrically connected with the output end of the constant current source, and a second pole of the tenth resistor is electrically connected with a first pole of the eighth capacitor;
the first pole of the six capacitors is electrically connected with the input end of the constant current source, and the second pole of the six capacitors is grounded;
the first pole of the seven capacitor is electrically connected with the input end of the constant current source, and the second pole of the seven capacitor is grounded;
a first pole of the eighth capacitor is electrically connected to the second pole of the tenth resistor, and the second pole of the eighth capacitor is grounded;
the first pole of the ninth capacitor is electrically connected with the second pole of the ninth resistor, and the second pole of the ninth capacitor is electrically connected with the output end of the constant current source.
Wherein the current source comprises a transient suppression diode, a first pole of the transient suppression diode is electrically connected to the output of the constant current source, and a second pole of the transient suppression diode is grounded.
The magnetic induction unit is a giant magnetoresistance effect element, a tunneling magnetoresistance effect element, an anisotropic magnetoresistance effect element, a giant magnetoresistance effect element or a Hall effect element.
The current measuring device is used for leakage current monitoring, lightning current monitoring, power transmission line monitoring and household appliance current monitoring.
The invention has the following beneficial effects:
the current measuring device provided by the invention adopts an open-loop form, two induction signals are obtained through the two magnetic induction units, the two induction signals are converted by the processing unit through the primary amplification unit, the secondary amplification unit sums and amplifies and the filtering unit selects a frequency band in sequence, the precision of the current measuring device is improved, the frequency band is expanded, the anti-interference capability is improved, and the current measuring device also has the advantages of simple structure, high reliability, strong overload capability and small size.
Drawings
FIG. 1 is a schematic structural diagram of a current measuring device according to an embodiment of the present invention;
FIG. 2 is a schematic block diagram of a current measuring device according to an embodiment of the present invention;
FIG. 3a is a circuit diagram of a first stage amplifying unit in the current measuring device according to the embodiment of the present invention;
FIG. 3b is a circuit diagram of a first stage amplifying unit in a current measuring device according to another embodiment of the present invention;
FIG. 3c is a circuit diagram of a first stage amplifying unit in a current measuring device according to another embodiment of the present invention;
FIG. 4 is a circuit diagram of a secondary amplifying unit in the current measuring device according to the embodiment of the present invention;
FIG. 5 is a circuit diagram of a connection between a primary amplification unit and a secondary amplification unit in a current measurement apparatus according to an embodiment of the present invention;
FIG. 6 is a circuit diagram of a filter unit in the current measuring device according to the present invention;
FIG. 7 is a circuit diagram of a current source in the current measuring device according to the embodiment of the present invention.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the following describes the current measuring device provided in the present invention in detail with reference to the accompanying drawings.
As shown in fig. 1 and fig. 2, the current measuring apparatus provided in the present embodiment includes a magnetic core 1, magnetic induction units 2a and 2b, and a processing unit 3, wherein the magnetic core 1 is used for collecting a magnetic field generated by a current flowing through a wire, an insertion hole 12 for disposing a wire to be measured is provided in the middle of the magnetic core 1, and two open air gaps 11a and 11b are provided at symmetrical positions of the magnetic core 1. Each open air gap is provided with a magnetic induction unit, that is, the magnetic induction units 2a and 2b are respectively arranged in the open air gaps 11a and 11b and used for inducing a magnetic field and outputting an induced signal (voltage signal or differential signal). Two input ends of the processing unit 3 are correspondingly and electrically connected with the output ends of the magnetic induction units 2a and 2b, and the processing unit is used for processing the induction signals and obtaining the current value flowing through the measured lead.
The current measuring device further comprises a support 4 and a housing 5, the support 4 is used for supporting and fixing the magnetic core 1, and the support 4 is embedded in the housing 5. The housing 5 serves to protect the magnetic core 1, the support 4 and the magnetic induction units 2a, 2 b. The processing unit 3 may be provided inside the housing 5 or outside the housing 5.
The processing unit 3 includes two primary amplifying units 31, two secondary amplifying units 32 and a filtering unit 33, wherein the output end of each magnetic induction unit 2a, 2b corresponds to one primary amplifying unit 31, and the primary amplifying unit 31 is configured to convert the differential signal obtained by the magnetic induction units 2a, 2b into a single-ended signal; the second-stage amplifying unit 32 is configured to sum and amplify the two single-ended signals to obtain an amplified signal; the filtering unit 33 is used to obtain the signal in the desired frequency band from the amplified signal. The first-stage amplification unit 31 and the second-stage amplification unit 32 can avoid amplifying the offset of the direct current signal, normally amplify the required alternating current signal, and avoid the dynamic range of the alternating current signal from becoming small.
As shown IN fig. 3a, each of the first-stage amplifying units 33 is an instrumentation amplifier, and includes a low noise amplifier U1 and a first resistor R1, wherein the input terminal IN-, IN + of each low noise amplifier U1 is electrically connected to the output terminals 2, 3 of a magnetic induction unit, and the output terminal VOUT of the low noise amplifier U1 is electrically connected to the input terminal of the second-stage amplifying unit 32. The first resistor R1 is a gain resistor, and two ends of the first resistor R1 are electrically connected to two gain ends RG1 and RG2 of the low noise amplifier U1.
The positive power supply terminal VCC and the negative power supply terminal VSS of the low noise amplifier U1 are connected to the required voltage, such as + 2.5V, ± 5V, ± 12V or + 18V, respectively, according to the actual use condition. The reference terminal REF of the low noise amplifier U1 is connected to ground.
Preferably, a transient suppression diode D1, D2 is disposed at the input terminal IN-, IN + of the low noise amplifier, wherein a first pole of the transient suppression diode D1 is electrically connected to the input terminal IN-, of the low noise amplifier, and a second pole of the transient suppression diode D1 is grounded; a first pole of the transient suppression diode D2 is electrically connected to the input terminal IN + of the low noise amplifier and a second pole of the transient suppression diode D2 is grounded.
FIG. 3b is a circuit diagram of a first stage amplifying unit in a current measuring device according to another embodiment of the present invention. As shown in fig. 3b, the first-stage amplifying unit includes a first amplifier U1, a second amplifier U2, a third amplifier U3, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5, wherein the high-voltage input terminal of the first amplifier U1 is electrically connected to the output terminals of the magnetic induction units 2a and 2 b.
A first pole of the first resistor R1 is electrically connected to the output terminal OUT1 of the first amplifier U1, and a second pole of the first resistor R1 is electrically connected to the high voltage input terminal of the third amplifier U3.
A first pole of the second resistor R2 is electrically connected to the low voltage input of the first amplifier U1, and a second pole of the second resistor R2 is electrically connected to the output OUT1 of the first amplifier U1.
A first pole of the third resistor R3 is electrically connected to the low voltage input of the first amplifier U1, and a second pole of the third resistor R3 is electrically connected to the output OUT2 of the second amplifier U2.
A first pole of the fourth resistor R4 is electrically connected to the low voltage input of the second amplifier U2, and a second pole of the fourth resistor R4 is electrically connected to the output OUT2 of the second amplifier U2.
A first pole of the fifth resistor R5 is electrically connected to the output terminal OUT2 of the second amplifier U2, and a second pole of the fifth resistor R5 is electrically connected to the low voltage input terminal of the third amplifier U3.
The primary amplification unit shown in fig. 3b can be used to amplify ac/dc voltage signals.
FIG. 3c is a circuit diagram of a first stage amplifying unit in a current measuring device according to another embodiment of the present invention. As shown in fig. 3C, the first-stage amplifying unit includes a first amplifier U1, a second amplifier U2, a third amplifier U3, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a first capacitor C1, wherein a high-voltage input terminal of the first amplifier U1 is electrically connected to output terminals of the magnetic induction units 2a and 2 b.
A first pole of the first resistor R1 is electrically connected to the output terminal OUT1 of the first amplifier U1, and a second pole of the first resistor R1 is electrically connected to the high voltage input terminal of the third amplifier U3.
A first pole of the second resistor R2 is electrically connected to the low voltage input of the first amplifier U1, and a second pole of the second resistor R2 is electrically connected to the output OUT1 of the first amplifier U1.
A first pole of the third resistor R3 is electrically connected to the low voltage input terminal of the first amplifier U1, and a second pole of the third resistor R3 is electrically connected to the first end of the first capacitor C1.
A first pole of the fourth resistor R4 is electrically connected to the low voltage input of the second amplifier U2, and a second pole of the fourth resistor R4 is electrically connected to the output OUT2 of the second amplifier U2.
A first pole of the fifth resistor R5 is electrically connected to the output terminal OUT2 of the second amplifier U2, and a second pole of the fifth resistor R5 is electrically connected to the low voltage input terminal of the third amplifier U3.
A first pole of the first capacitor C1 is electrically connected to a second pole of the third resistor R3, and a second pole of the first capacitor C1 is electrically connected to the high voltage input terminal of the second amplifier U2.
The primary unit shown in fig. 3c is used to amplify the ac voltage signal.
As shown in fig. 4, the two-stage amplifying unit 32 includes a first operational amplifier U2, a second resistor R2, a third resistor R3 and a fourth resistor R4, a first pole of the second resistor R2 is electrically connected to an output terminal OUT of a low noise amplifier U1, and a second pole of the second resistor R2 is electrically connected to a low voltage input terminal of the first operational amplifier U2; a first pole of the third resistor R3 is electrically connected to the output terminal OUT of the other low noise amplifier U1, and a second pole of the third resistor R3 is electrically connected to the low voltage input terminal of the first operational amplifier U2; a first pole of the fourth resistor R4 is electrically connected to the low-voltage input terminal of the first operational amplifier U2, and a second pole of the fourth resistor R4 is electrically connected to the output terminal OUT of the first operational amplifier U2; the high voltage input of the first operational amplifier U2 is connected to ground. The second resistor R2 and the third resistor R3 are used for summation, and the second resistor R2, the third resistor R3 and the fourth resistor R4 form amplification.
Preferably, the two-stage amplifying unit 32 includes a first capacitor C1, a first pole of the first capacitor C1 is electrically connected to the low voltage input terminal of the first operational amplifier U2, and a second pole of the first capacitor C1 is electrically connected to the output terminal of the first operational amplifier U2. The first capacitor C1 may be used to eliminate self-excitation of the two-stage amplification unit 32.
More preferably, as shown in fig. 5, a dc blocking capacitor C0 is disposed between the output terminal OUT of the low noise amplifier U1 and the first pole of the second resistor R2, and between the output terminal OUT of the low noise amplifier U1 and the first pole of the third resistor R3. The dc blocking capacitor C0 is used to isolate the dc signal of the primary amplification unit 31.
The filtering unit 33 may filter high frequency components in the measurement signal to extract a signal in a desired frequency band from the measurement signal. As shown in fig. 6, the filtering unit 33 includes a filtering operational amplifier U3, a fifth resistor R5, a sixth resistor R6, a second capacitor C2, and a third capacitor C3; wherein,
a first pole of the fifth resistor R5 is electrically connected to the output terminal OUT of the first operational amplifier U2, and a second pole of the fifth resistor R5 is electrically connected to a first pole of the sixth resistor R6.
The second pole of the sixth resistor R6 is electrically connected to the high voltage input of the filtering operational amplifier U3.
The first pole of the second capacitor C2 is electrically connected to the second pole of the fifth resistor R5 and the first pole of the sixth resistor R6, and the second pole of the second capacitor C2 is electrically connected to the output terminal of the filtering operational amplifier U3.
The first pole of the third capacitor C3 is electrically connected to the high voltage input of the filtering operational amplifier U3, and the second pole of the third capacitor C3 is grounded.
The low voltage input terminal of the filtering operational amplifier U3 is electrically connected to the output terminal OUT of the filtering operational amplifier U3.
Preferably, a transient suppression diode D5 is disposed at the output of the filtering operational amplifier U3, a first pole of the transient suppression diode D5 is electrically connected to the output of the filtering operational amplifier U3, and a second pole of the transient suppression diode D5 is grounded. The transient suppression diode D5 is advantageous for enhancing the anti-electromagnetic interference capability of the processing unit.
In this embodiment, the magnetic induction units 2a and 2b respectively include a substrate and a plurality of sets of magnetic induction units, the plurality of sets of magnetic induction units are electrically connected to form a wheatstone bridge, for example, the magnetic induction units include four magnetic induction units, and the four magnetic induction units are built into a wheatstone full-bridge circuit; for another example, the magnetic induction unit includes two magnetic induction units, and the two magnetic induction units are built into a wheatstone half-bridge circuit. A wheatstone full bridge will be described as an example. The two output ends of the Wheatstone bridge are the output ends of the magnetic induction unit, and the magnetic induction unit needs a power supply to supply power for the magnetic induction unit. Therefore, the current measuring device further comprises a current source for providing a current signal to the magnetic induction unit. The current source provided by the embodiment has better linearity.
As shown in fig. 7, the current source includes a constant current source U4, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, and a ninth capacitor C9; the constant current source is provided with an input end IN, an output end OUT and a setting end SET.
A first pole of the seventh resistor R7 is electrically connected to the output terminal IN of the constant current source U4, and a second pole of the seventh resistor R7 is electrically connected to the output terminal OUT of the constant current source U4.
A first pole of the eighth resistor R8 is electrically connected to the SET terminal SET of the constant current source U4, and a second pole of the eighth resistor R8 is electrically connected to the output terminal OUT of the constant current source U4.
A first pole of the ninth resistor R9 is electrically connected to the input terminal IN of the constant current source U4, and a second pole of the ninth resistor R9 is electrically connected to the first pole of the ninth capacitor C9.
A first pole of the tenth resistor R10 is electrically connected to the output terminal OUT of the constant current source U4, and a second pole of the tenth resistor R10 is electrically connected to the first pole of the eighth capacitor C8.
A first pole of the sixth capacitor C6 is electrically connected to the input terminal IN of the constant current source U4, and a second pole of the sixth capacitor R6 is grounded.
A first pole of the seventh capacitor C7 is electrically connected to the input terminal IN of the constant current source U4, and a second pole of the seventh capacitor R7 is grounded.
A first pole of the eighth capacitor C8 is electrically connected to a second pole of the tenth resistor R10, and a second pole of the eighth capacitor C8 is grounded.
A first pole of the ninth capacitor C9 is electrically connected to the second pole of the ninth resistor R9, and a second pole of the ninth capacitor C9 is electrically connected to the output terminal OUT of the constant current source U4.
The sixth capacitor C6 and the seventh capacitor C7 are used for power supply filtering and eliminating voltage noise. The seventh resistor R7 and the eighth resistor R8 are used for determining the magnitude of the output current, and the eighth capacitor C8, the ninth capacitor C9, the ninth resistor R9 and the tenth resistor R10 are used for eliminating the oscillation of the current source.
Preferably, the current source further includes a transient suppression diode D6, a first pole of the transient suppression diode D6 is electrically connected to the output of the constant current source U4, and a second pole of the transient suppression diode D6 is grounded. The transient suppression diode D6 may improve the current source's resistance to electromagnetic interference.
In this embodiment, the magnetic induction unit is a giant magnetoresistance effect element, a tunneling magnetoresistance effect element, an anisotropic magnetoresistance effect element, a giant magnetoresistance effect element, or a hall effect element.
The current measuring device provided by the embodiment can be used in the fields of leakage current monitoring, lightning current monitoring, household appliance current monitoring or power transmission line monitoring and the like. This current measurement device open loop current measurement device obtains two induction signals through two magnetic induction units, and these two induction signals are passed through one-level amplification unit conversion, second grade amplification unit summation amplification and filtering unit selection frequency channel by the processing unit in proper order, make it reach closed loop current measurement device's precision, frequency band, but also kept open loop current measurement device's simple structure, reliability height, overload capacity are strong, interference killing feature is strong, advantages such as small. In addition, the current measuring device can eliminate potential high-voltage conditions, avoid damaging a circuit and prevent fire.
The measuring device provided by the invention can be used in the fields of leakage current monitoring, power transmission line current monitoring, household appliance current monitoring, lightning current monitoring, automobile circuit current monitoring, Internet of things current monitoring, intelligent broadband current monitoring and the like, and has the advantages of high measuring precision, strong anti-interference capability, wide frequency band and the like.
It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.
Claims (13)
1. A current measuring device comprises a magnetic core, a magnetic induction unit and a processing unit, wherein,
the magnetic core is used for gathering a magnetic field generated by current flowing through the lead, and an open air gap is arranged on the magnetic core;
the magnetic induction unit is arranged in the open air gap and used for inducing a magnetic field and outputting an induction signal;
the input end of the processing unit is electrically connected with the output end of the magnetic induction unit and is used for processing the induction signal and obtaining the current value flowing through the measured lead;
the magnetic core is symmetrically provided with two open air gaps, and each open air gap is provided with one magnetic induction unit;
the processing unit comprises two primary amplifying units, a secondary amplifying unit and a filtering unit, wherein the output end of each magnetic induction unit corresponds to one primary amplifying unit, and the primary amplifying units are used for converting the induction signals into single-ended signals; the two-stage amplifying unit is used for summing and amplifying the two single-ended signals to obtain an amplified signal; the filtering unit is used for obtaining signals in a required frequency band from the amplified signals.
2. The current measuring device of claim 1, wherein each of the primary amplification units comprises a low noise amplifier and a first resistor, wherein,
the input end of each low-noise amplifier is electrically connected with the output end of one magnetic induction unit, and the output end of each low-noise amplifier is electrically connected with the input end of the secondary amplification unit;
and two ends of the first resistor are correspondingly and electrically connected with two gain ends of the low-noise amplifier.
3. The current measuring device according to claim 1, wherein each of the primary amplifying units comprises a first amplifier, a second amplifier, a third amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor, wherein a high voltage input terminal of the first amplifier is electrically connected to an output terminal of the magnetic induction unit;
the first pole of the first resistor is electrically connected with the output end of the first amplifier, and the second pole of the first resistor is electrically connected with the high-voltage input end of the third amplifier;
the first pole of the second resistor is electrically connected with the low-voltage input end of the first amplifier, and the second pole of the second resistor is electrically connected with the output end of the first amplifier;
the first pole of the third resistor is electrically connected with the low-voltage input end of the first amplifier, and the second pole of the third resistor is electrically connected with the output end of the second amplifier;
the first pole of the fourth resistor is electrically connected with the low-voltage input end of the second amplifier, and the second pole of the fourth resistor is electrically connected with the output end of the second amplifier;
the first pole of the fifth resistor is electrically connected with the output end of the second amplifier, and the second pole of the fifth resistor is electrically connected with the low-voltage input end of the third amplifier.
4. The current measuring device according to claim 1, wherein each of the primary amplifying units comprises a first amplifier, a second amplifier, a third amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a first capacitor, wherein a high voltage input terminal of the first amplifier is electrically connected to an output terminal of the magnetic induction unit;
the first pole of the first resistor is electrically connected with the output end of the first amplifier, and the second pole of the first resistor is electrically connected with the high-voltage input end of the third amplifier;
the first pole of the second resistor is electrically connected with the low-voltage input end of the first amplifier, and the second pole of the second resistor is electrically connected with the output end of the first amplifier;
the first pole of the third resistor is electrically connected with the low-voltage input end of the first amplifier, and the second pole of the third resistor is electrically connected with the first end of the first capacitor;
the first pole of the fourth resistor is electrically connected with the low-voltage input end of the second amplifier, and the second pole of the fourth resistor is electrically connected with the output end of the second amplifier;
the first pole of the fifth resistor is electrically connected with the output end of the second amplifier, and the second pole of the fifth resistor is electrically connected with the low-voltage input end of the third amplifier;
the first pole of the first capacitor is electrically connected with the second pole of the third resistor, and the second pole of the first capacitor is electrically connected with the high-voltage input end of the second amplifier.
5. The current measuring device according to any one of claims 2-4, wherein the secondary amplifying unit comprises a first operational amplifier, a second resistor, a third resistor and a fourth resistor, a first pole of the second resistor is electrically connected to an output terminal of the low noise amplifier, and a second pole of the second resistor is electrically connected to a low voltage input terminal of the first operational amplifier; the first pole of the third resistor is electrically connected with the output end of the other low-noise amplifier, and the second pole of the third resistor is electrically connected with the low-voltage input end of the first operational amplifier; a first pole of the fourth resistor is electrically connected with the low-voltage input end of the first operational amplifier, and a second pole of the fourth resistor is electrically connected with the output end of the first operational amplifier; the high-voltage input end of the first operational amplifier is grounded.
6. The current measuring device of claim 5, wherein the secondary amplifying unit comprises a first capacitor, a first pole of the first capacitor is electrically connected to the low voltage input terminal of the first operational amplifier, and a second pole of the first capacitor is electrically connected to the output terminal of the first operational amplifier.
7. The current measuring device of claim 5, wherein a blocking capacitor is disposed between the output of the low noise amplifier and the first pole of the second resistor and between the output of the low noise amplifier and the first pole of the third resistor.
8. The current measuring device of claim 5, wherein the filtering unit comprises a filtering operational amplifier, a fifth resistor, a sixth resistor, a second capacitor and a third capacitor;
a first pole of the fifth resistor is electrically connected with the output end of the first operational amplifier, and a second pole of the fifth resistor is electrically connected with a first pole of the sixth resistor;
the second pole of the sixth resistor is electrically connected with the high-voltage input end of the filtering operational amplifier;
the first pole of the second capacitor is electrically connected with the second pole of the fifth resistor and the first pole of the sixth resistor, and the second pole of the second capacitor is electrically connected with the output end of the filtering operational amplifier;
the first pole of the third capacitor is electrically connected with the high-voltage input end of the filtering operational amplifier, and the second pole of the third capacitor is grounded;
and the low-voltage input end of the filtering operational amplifier is electrically connected with the output end of the filtering operational amplifier.
9. The current measuring apparatus of claim 8, wherein a transient suppression diode is provided at the input of each of the low noise amplifiers, a first pole of the transient suppression diode being electrically connected to the input of the low noise amplifier, and a second pole of the transient suppression diode being connected to ground;
and a transient suppression diode is arranged at the output end of the filtering operational amplifier, the first pole of the transient suppression diode is electrically connected with the output end of the filtering operational amplifier, and the second pole of the transient suppression diode is grounded.
10. The current measuring device according to claim 1, wherein the magnetic induction unit comprises a substrate and a plurality of sets of magnetic induction units, the plurality of sets of magnetic induction units are electrically connected to form a wheatstone bridge, and two output ends of the wheatstone bridge are output ends of the magnetic induction units;
the current measuring device comprises a current source, the current source is used for providing electric energy for the Wheatstone bridge, and the current source comprises a constant current source, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a sixth capacitor, a seventh capacitor, an eighth capacitor and a ninth capacitor; the constant current source comprises an input end, an output end and a setting end;
a first pole of the seventh resistor is electrically connected with the output end of the constant current source, and a second pole of the seventh resistor is electrically connected with the output end of the constant current source;
a first pole of the eighth resistor is electrically connected with the setting end of the constant current source, and a second pole of the eighth resistor is electrically connected with the output end of the constant current source;
the first pole of the ninth resistor is electrically connected with the input end of the constant current source, and the second pole of the ninth resistor is electrically connected with the first pole of the ninth capacitor;
a first pole of the tenth resistor is electrically connected with the output end of the constant current source, and a second pole of the tenth resistor is electrically connected with a first pole of the eighth capacitor;
the first pole of the six capacitors is electrically connected with the input end of the constant current source, and the second pole of the six capacitors is grounded;
the first pole of the seven capacitor is electrically connected with the input end of the constant current source, and the second pole of the seven capacitor is grounded;
a first pole of the eighth capacitor is electrically connected to the second pole of the tenth resistor, and the second pole of the eighth capacitor is grounded;
the first pole of the ninth capacitor is electrically connected with the second pole of the ninth resistor, and the second pole of the ninth capacitor is electrically connected with the output end of the constant current source.
11. The current measurement device of claim 10, wherein the current source comprises a transient suppression diode, a first pole of the transient suppression diode being electrically connected to the output of the constant current source, and a second pole of the transient suppression diode being connected to ground.
12. The current measuring apparatus according to claim 10, wherein the magnetic induction unit is a giant magnetoresistance effect element, a tunneling magnetoresistance effect element, an anisotropic magnetoresistance effect element, a giant magnetoresistance effect element, or a hall effect element.
13. Current measuring device according to any of claims 1-12, characterized in that the current measuring device is used for leakage current monitoring, lightning current monitoring, transmission line monitoring and household appliance current monitoring.
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| CN201510624132.6A CN106556729A (en) | 2015-09-27 | 2015-09-27 | A kind of current measuring device |
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| CN201510624132.6A CN106556729A (en) | 2015-09-27 | 2015-09-27 | A kind of current measuring device |
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| CN107656086A (en) * | 2017-08-31 | 2018-02-02 | 深圳中广核工程设计有限公司 | A kind of nuclear power station main pump tach signal monitoring system and method |
| CN111964768A (en) * | 2020-08-05 | 2020-11-20 | 青岛英泰软件技术有限公司 | Filtering method for increasing anti-interference effect of electronic scale |
| CN113638834A (en) * | 2020-04-27 | 2021-11-12 | 上海华依科技集团股份有限公司 | Magnetic induction device for engine ignition test |
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| CN101561458A (en) * | 2009-05-26 | 2009-10-21 | 刘海先 | Method and device for measuring current on line |
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