CN110187158A - A kind of two-wire system Hall-type RMS current transmitter - Google Patents
A kind of two-wire system Hall-type RMS current transmitter Download PDFInfo
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- CN110187158A CN110187158A CN201910571276.8A CN201910571276A CN110187158A CN 110187158 A CN110187158 A CN 110187158A CN 201910571276 A CN201910571276 A CN 201910571276A CN 110187158 A CN110187158 A CN 110187158A
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
The invention patent discloses a kind of two-wire system Hall-type RMS current transmitter, the transmitter is mainly by C-shaped magnet ring, Hall sensor, differential amplifier circuit, virtual value detecting circuit, V/I conversion circuit, two-wire system output loop, bias-voltage generating circuit, common mode resistance-capacitance network composition, tested electric current passes through C-shaped magnet ring, Hall sensor is installed in C-shaped magnet ring air gap, Hall sensor voltage output is connected to differential amplifier circuit input terminal, differential amplifier circuit output is connected to virtual value detecting circuit input terminal, the output of virtual value detecting circuit is connected to V/I conversion circuit input terminal, the output of bias-voltage generating circuit is connected to differential amplifier circuit and virtual value detecting circuit bias voltage input, the output of V/I conversion circuit is connected to two-wire system output loop, pass through two-wire system output loop output 4~20 MA current signal, meanwhile, V/I conversion circuit output current source and voltage source are respectively Hall sensor and the power supply of each circuit link.
Description
Technical field
The invention patent relates to electrical detection technique and automation equipment fields, more specifically, the invention patent relates to
A kind of two-wire system Hall-type RMS current transmitter meter.
Background technique
RMS current transmitter is widely used in power automation, relay protection, motor control, industrial automation etc.
The virtual value of the AC or DC electric current of tested major loop is converted to 4 by linear relationship by the metering of the power and electric energy in field
~20mA standard DC current signal export and remote transmission.
Hall sensor is a kind of most common sensor measured to magnetic field or electric current, has high sensitivity, knot
The advantages that structure is simple, small in size, frequency response range is wide and long service life, it is equal to the measurement in AC and DC magnetic field or electric current
It is applicable in, and is suitable for the measurement of quiescent current and dynamic current, therefore construct current transducer by sensing element of Hall sensor
With unrivaled superiority.
Existing most of Hall-type current transducers use three-wire system or the four-wire system mode of connection, in addition to signal is transmitted back to
It outside road, also needs in addition to provide electric power loop for transmitter, wiring is complicated, maintenance is inconvenient.For example, application No. is
201320382320.9 " a kind of rail type installation current transducer based on Hall closed loop principle " uses closed-loop feed-back type
Working principle, operating circuit structure is complex, and special current supply circuit is needed to provide+Vc and two electricity of-Vc therein
Source is needed using the four-wire system mode of connection.
However, the two-wire system Hall-type current transducer mode of connection is more simple, reliable, and it is easy to use, it is widely used in each
Kind measurement and control system, therefore there is the current transducer for developing 4~20mA of two-wire system standard signal great technology to develop valence
Value and the extensive market demand.Application No. is " a kind of two-wire system Hall-type current transducers " of 201810424278.X then to use
The output form of two-wire system 4~20mA standard signal, but the transmitter is only used for the measurement of ac and dc current instantaneous value, nothing
RMS current measures function.
The total current that two-wire system Hall-type RMS current transmitter does not require nothing more than system work is less than 4mA, i.e., entire system
System needs to carry out low power dissipation design, should also have the function of carrying out virtual value detection to measuring signal, there is biggish development difficulty.
The invention patent provides a solution for the realization of two-wire system Hall-type RMS current transmitter.
Patent of invention content
The technical problem to be solved is that the surveys that ac and dc current virtual value is realized using Hall sensor for the invention patent
Amount, and signal transmission and system power supply can be carried out by two-wire system standard 4~20mA current loop.
In order to solve the technical problem, the invention patent provides a kind of two-wire system Hall-type RMS current pick-up
Device, it is characterised in that: the transmitter is mainly by C-shaped magnet ring, Hall sensor, differential amplifier circuit, virtual value detecting circuit, V/
I conversion circuit, two-wire system output loop, bias-voltage generating circuit, common mode resistance-capacitance network composition, are tested electric current ImAcross C-shaped
Magnet ring, Hall sensor are installed in the air gap of C-shaped magnet ring, and the voltage output of Hall sensor is connected to differential amplifier circuit
Input terminal, the output of differential amplifier circuit are connected to the input terminal of virtual value detecting circuit, the output end of virtual value detecting circuit
It is connected to the input terminal of V/I conversion circuit, the output of bias-voltage generating circuit is connected to differential amplifier circuit and virtual value detection
The bias voltage input of circuit, the output of V/I conversion circuit are connected to two-wire system output loop, and V/I conversion circuit
Constant current source output terminal is connected to the exciting current input terminal of Hall sensor, and the constant pressure source output terminal of V/I conversion circuit is connected to differential
The power end of amplifying circuit, virtual value detecting circuit and bias-voltage generating circuit, common mode resistance-capacitance network connect in Hall sensor
Exciting current return terminal and V/I conversion circuit constant pressure source and constant-current source return reference ground between.
In measurement process, across the tested electric current I of C-shaped magnet ringmIt is generated and tested electric current I in magnet ringmSize is directly proportional
Toroidal magnetic field, which passes perpendicularly through Hall sensor, and Hall sensor is passed through the excitation electricity provided by V/I conversion circuit
Stream, therefore the output of the voltage output end of Hall sensor and tested electric current ImThe directly proportional weak voltage signals of instantaneous value, the electricity
Pressure signal is input to virtual value detecting circuit after differential amplifier circuit amplifies, and virtual value detecting circuit believes the exchange of input
It number is converted to and tested electric current ImThe directly proportional d. c. voltage signal of virtual value, and be input to V/I conversion circuit, V/I conversion
The voltage signal of input is converted to 4~20mA current signal by circuit, and carries out signal transmission by two-wire system output loop, and partially
The voltage signal for setting voltage generation circuit output is input to the bias voltage input of differential amplifier circuit and virtual value detecting circuit
End provides syntype bias voltage appropriate for virtual value detection process, and the conversion circuit output constant current source V/I is hall sensing
Device provides exciting current signal, which passes through common mode capacitance-resistance net after the outflow of the exciting current return terminal of Hall sensor
Network and the pressure drop that generates provide input common mode voltage appropriate for differential amplifier circuit, and it is poor that V/I conversion circuit, which exports constant pressure source,
Dynamic amplifying circuit, virtual value detecting circuit and bias-voltage generating circuit provide working power.
The differential amplifier circuit is mainly made of high-precision, micro energy lose instrument amplifier AD627, the virtual value detection
Circuit is mainly made of accurate micro energy lose rms detector LTC1966, and the difference voltage signal of Hall sensor output is connected to
The differential input end of AD627, and the output offset side of AD627 accesses the bias voltage generated by bias-voltage generating circuit,
Insertion gain adjusts potentiometer between No. 1 of AD627 and No. 8 feet, which can be used for the adjustment of transmitter measuring range,
The output of AD627 is connected to the normal phase input end of LTC1966, and the bias voltage of bias-voltage generating circuit output accesses simultaneously
The inverting input terminal and output offset side, the bias voltage of LTC1966 provides common mode operation voltage appropriate for LTC1966, together
When LTC1966 output end and output offset side between and access detection period capacitor.
The V/I conversion circuit is mainly made of voltage/current transformation chip XTR105, and input voltage is linearly turned
4~20mA electric current is changed to be exported, the DC voltage of virtual value detecting circuit output is input to the normal phase input end of XTR105,
And the voltage-regulating circuit in series by 2 fixed resistances and 1 potentiometer, potentiometer are connected in V/I conversion circuit
Centre cap is connected to the inverting input terminal of XTR105, and the adjustment voltage of potentiometer centre cap output can provide suitably for XTR105
Common mode operation voltage, and can be used for transmitter measurement zero point adjustment, in addition, the times magnification for thering is fixed resistance to be connected to XTR105
Number adjustment end, the resistance determine the voltage/current conversion coefficient of XTR105, meanwhile, XTR105 exports 2 road 0.8mA constant-current sources,
It will be input to Hall sensor after 2 road constant-current sources parallel connections, as the excitation current source of Hall sensor, which also exports 1 tunnel
The constant pressure source of 5.1V, 1mA capacity, the work as differential amplifier circuit, virtual value detecting circuit and bias-voltage generating circuit
Power supply.
The bias-voltage generating circuit is made of 2 series connection divider resistances and low consumed power operational amplifier MAX4480
Follower composition, 2 series resistances connect V/I conversion circuit generate 5.1V voltage source between, series connection point is connected to MAX4480
Normal phase input end, inverting input terminal is connected with output end, generates 1.6V bias voltage in output end.
The total power consumption of the differential amplifier circuit, virtual value detecting circuit and bias-voltage generating circuit is extremely low, transmitter
The total current in internal work circuit is less than 4mA, so as to realize that with 4mA be the two-wire system electric current output for measuring zero point.
The two-wire system output loop mainly by NPN type driving triode, overvoltage protection diode, diode rectifier bridge,
Load resistance and external power supply form, and the diode rectifier bridge in circuit has reverse connecting protection effect, and external power supply can be by any
Two-wire system output loop is accessed in direction, and 4~20mA current signal is exported and transmitted by two-wire system output loop, while being inside
Performance loop power supply.
The common mode resistance-capacitance network is made of 1 potentiometer and 1 capacitor parallel connection, and is connected on swashing for Hall sensor
Between the reference ground that the constant pressure source and constant-current source for encouraging electrical return and V/I conversion circuit return, the output of V/I conversion circuit
1.6mA constant-current source flows through common mode resistance-capacitance network, so as to provide by adjusting the resistance value of potentiometer for the work of differential amplifier
Common-mode voltage appropriate, and capacitor can filter out the ripple of the common-mode voltage.
The invention patent is include at least the following beneficial effects:
(1) virtual value detection function is increased on the basis of Hall-type transient current detects, can be used for AC and DC
The measurement of current effective value.
(2) the two-wire system mode of connection and 4~20mA standard current signal transmission mode are used, current supply circuit and signal return
Road is combined into one, and is shared a circuit, diode rectifier bridge heap is connected in output loop, two connecting terminals are without just on the contrary
Point, so that wiring is more succinctly, conveniently, reliably.
(3) the measurement output signal of Hall sensor is handled and is converted using pure analog circuit, turned without analog/digital
It changes and digital signal processor, also without complicated closed-loop feedback circuit, operating circuit structure is simple, low in cost, cost performance
It is high.
(4) it is connected to zero point in transmitter circuit and range adjusts potentiometer, the measurement zero point of transmitter and range adjustment side
Just, using flexible, conveniently.
(5) imbalance of the volt age offset of Hall sensor and differential amplifier, rms detector and V/I converter
Voltage can adjust voltage by zero point and be offset, and Hall sensor uses constant current source forcing, and keep temperature coefficient big
It is big to reduce, therefore the current transducer measurement accuracy is high.
(6) bias-voltage generating circuit and common mode resistance-capacitance network, the common mode of each signal conversion circuit link are connected in system
Bias voltage is appropriate, and static system operating point is reasonable, and measuring circuit precision is high, the linearity is good.
The further advantage, target and feature of the invention patent will be partially reflected by the following instructions, and part will also pass through
Research and practice to the invention patent and be understood by the person skilled in the art.
Detailed description of the invention
Fig. 1 is the theory of constitution schematic diagram of two-wire system Hall-type RMS current transmitter described in the invention patent.
Fig. 2 is the specific implementation circuit diagram of two-wire system Hall-type RMS current transmitter described in the invention patent.
Specific embodiment
The invention patent is described in further detail with reference to the accompanying drawing, to enable those skilled in the art referring to explanation
Book text can be implemented accordingly.It should be appreciated that such as " having ", "comprising" and " comprising " term used herein are not arranged
Except the presence or addition of one or more of the other element or combinations thereof.
In order to solve the technical problem, the invention patent provides a kind of two-wire system Hall-type RMS current pick-up
Device, as shown in Figure 1, the transmitter is mainly by C-shaped magnet ring 1, Hall sensor 2, differential amplifier circuit 3, virtual value detecting circuit
4, V/I conversion circuit 5, two-wire system output loop 6, bias-voltage generating circuit 7, common mode resistance-capacitance network 8 form, and are tested electric current Im
Across C-shaped magnet ring 1, Hall sensor 2 is installed in the air gap of C-shaped magnet ring 1, and the voltage output of Hall sensor 2 is connected to difference
The input terminal of dynamic amplifying circuit 3, the output of differential amplifier circuit 3 are connected to the input terminal of virtual value detecting circuit 4, virtual value inspection
The output of wave circuit 4 is connected to the input terminal of V/I conversion circuit 5, and the output of bias-voltage generating circuit 7 is connected to differential amplification
The bias voltage input of circuit 3 and virtual value detecting circuit 4, the output of V/I conversion circuit 5 are connected to two-wire system output loop
6, and the constant current source output terminal of V/I conversion circuit 5 is connected to the exciting current input terminal of Hall sensor 2, V/I conversion circuit 5
Constant pressure source output terminal be connected to the power end of differential amplifier circuit 3, virtual value detecting circuit 4 and bias-voltage generating circuit 7, altogether
Mould resistance-capacitance network 8 connects to be returned in the exciting current return terminal of Hall sensor 2 and the constant pressure source of V/I conversion circuit 5 and constant-current source
Reference ground between.
As shown in Figure 1, in measurement process, across the tested electric current I of C-shaped magnet ring 1mIt is generated and tested electric current I in magnet ringm
The directly proportional toroidal magnetic field of size, which passes perpendicularly through Hall sensor 2, and Hall sensor 2 is passed through by V/I conversion circuit
5 exciting currents provided, therefore the output of the voltage output end of Hall sensor 2 and tested electric current ImDirectly proportional faint of instantaneous value
Voltage signal, the voltage signal are input to virtual value detecting circuit 4, virtual value detection electricity after the amplification of differential amplifier circuit 3
Road 4 is converted to the AC signal of input and tested electric current ImThe directly proportional d. c. voltage signal of virtual value, and be input to V/I
Conversion circuit 5, the voltage signal of input is converted to 4~20mA current signal by V/I conversion circuit 5, and is exported back by two-wire system
Road 6 carries out signal transmission, and the voltage signal that bias-voltage generating circuit 7 exports is input to differential amplifier circuit 3 and virtual value
The bias voltage input of detecting circuit 4 provides syntype bias voltage appropriate for virtual value detection process, and V/I is converted
5 output constant current source of circuit is that Hall sensor 2 provides exciting current signal, exciting current of the constant-current source from Hall sensor 2
The pressure drop for passing through common mode resistance-capacitance network 8 after return terminal outflow and generating is that differential amplifier circuit 3 provides common mode input appropriate
Voltage, it is differential amplifier circuit 3, virtual value detecting circuit 4 and bias-voltage generating circuit 7 that V/I conversion circuit 5, which exports constant pressure source,
Working power is provided.
As shown in Figure 1, the C-shaped magnet ring 1 uses zinc-manganese ferrite bead, magnet ring is radially provided with 2mm air gap, it is described suddenly
You use TO-92 to encapsulate linear hall sensor HG-302C by sensor 2, and laminar Hall sensor 2 is parallelly mounted to C-shaped
The air gap center of magnet ring 1.Tested electric current ImIt motivates the magnetic field of generation to pass through air gap in C-shaped magnet ring 1 and passes perpendicularly through Hall biography
Two surfaces up and down of sensor 2, air-gap field intensity B and tested electric current ImIt is directly proportional, and Hall sensor 2 is passed through by V/I
The exciting current I that conversion circuit 5 providesH, voltage output end output and the tested electric current I of Hall sensor 2mInstantaneous value is directly proportional
Weak voltage signals UHIt is represented by
UH=UH+-UH-=kIHB (1)
In formula, k is the Hall coefficient of Hall sensor.It is found that the output voltage U of Hall sensorHWith tested electric current ImAt
Direct ratio.
As shown in Fig. 2, the differential amplifier circuit 3 is mainly made of high-precision, micro energy lose instrument amplifier AD627, institute
It states virtual value detecting circuit 4 to be mainly made of accurate micro energy lose rms detector LTC1966, the difference that Hall sensor 2 exports
Dynamic voltage signal is connected to the differential input end of AD627, and the output offset side of AD627 is accessed by bias-voltage generating circuit 7
The bias voltage U of generationref, insertion gain adjusts potentiometer R between No. 1 of AD627 and No. 8 feet3, then differential amplifier circuit 3
Output voltage UDIt is represented by
UD=UH×(5+200/R3)+Uref (2)
In formula, RUFor the resistance value for connecing the gain adjustment potentiometer between 1 foot and 8 feet of AD627, value range 0
~1k Ω, the potentiometer can be used for the adjustment of transmitter measuring range, UrefThe biased electrical generated for bias-voltage generating circuit 7
Pressure.The output of AD627 is connected to the normal phase input end IN1 of LTC1966, the bias voltage U that bias-voltage generating circuit 7 exportsref
The inverting input terminal IN2 and output offset side VOUT_RTN of LTC1966 are accessed simultaneously, which provides suitable for LTC1966
When common mode operation voltage, while the output end VOUT of LTC1966 and output offset side VOUT_RTN between and access 1 μ F inspection
Wave period capacitor CAVE, then virtual value detecting circuit 4 export DC voltage URMSIt is represented by
In formula, T=RoCAVEFor by the inside output resistance R of LTC1966o=85k Ω and external capacitor CAVE=1 μ F is determined
The detection period, UrefThe bias voltage generated for bias-voltage generating circuit 7.
As shown in Fig. 2, the V/I conversion circuit 5 is mainly made of voltage/current transformation chip XTR105, it will input
It is converted to voltage linear 4~20mA electric current to be exported, the DC voltage U that virtual value detecting circuit 4 exportsRMSIt is input to
The normal phase input end VIN+ of XTR105, and be connected in V/I conversion circuit 5 by R4=2.2M Ω, R6=1M Ω fixed resistance and
R5=200k Ω potentiometer voltage-regulating circuit in series, potentiometer centre cap are connected to the inverting input terminal of XTR105
VIN-, the adjustment voltage U of potentiometer centre cap outputoffCommon mode work appropriate within the scope of 1.5~1.8V can be provided for XTR105
Make voltage, and can be used for the adjustment of transmitter measurement zero point.In addition, there is fixed resistance R7=1k Ω is connected to the times magnification of XTR105
Number adjustment end, the resistance determine the voltage/current conversion coefficient of XTR105, then XTR105 is exported to two-wire system output loop 6
Electric current I0For
I0=4+40 × (URMS-Uoff)/R7 (4)
In formula, URMSFor the DC voltage that virtual value detecting circuit 4 exports, UoffFor potentiometer R5The tune of centre cap output
Whole voltage, adjusting range is between 1.5~1.8V, I0To export electric current, R7=1k Ω is the gain adjustment resistance of XTR105
Resistance value.Meanwhile XTR105 exports 2 road 0.8mA constant-current sources, Hall sensor 2 will be input to after 2 road constant-current sources parallel connections, as suddenly
The excitation current source of your sensor 2, the chip also export the constant pressure source of 1 road 5.1V, 1mA capacity, as differential amplifier circuit 3,
The working power of virtual value detecting circuit 4 and bias-voltage generating circuit 7.
As shown in Fig. 2, the bias-voltage generating circuit 7 is by R1=2.2M Ω and R2=1M Ω connect divider resistance and
The follower composition that low consumed power operational amplifier MAX4480 is constituted, 2 series resistances meet the 5.1V generated in V/I conversion circuit 5
Between voltage source, series connection point is connected to the normal phase input end of MAX4480, and inverting input terminal is connected with output end, therefore in its output end
The bias voltage U of generationref=1.6V can provide syntype bias voltage appropriate for virtual value detection process.
The total power consumption of the differential amplifier circuit 3, virtual value detecting circuit 4 and bias-voltage generating circuit 7 is extremely low, pick-up
The total current in device internal work circuit is less than 4mA, so as to realize that with 4mA be the two-wire system electric current output for measuring zero point.
The two-wire system output loop 6 mainly by NPN type driving triode, overvoltage protection diode, diode rectifier bridge,
Load resistance and external power supply form, and the diode rectifier bridge in circuit has reverse connecting protection effect, and external power supply can be by any
Two-wire system output loop 6 is accessed in direction, is exported by two-wire system output loop 6 and transmits 4~20mA current signal, while being interior
The power supply of portion's performance loop.Specific embodiment is as shown in Fig. 2, the NPN type driving triode Q1Using 9014, to improve pick-up
Device current output capability reduces the fever of XTR105 chip, triode Q1Base stage be connected with No. 9 pins of XTR105, Q1Emitter-base bandgap grading
It is connected with No. 8 pins of XTR105, Q1Collector be connected and be connected to the one of diode rectifier bridge with No. 10 pins of XTR105
A vertex；The overvoltage protection diode D5Using 36V Zener diode 1N4753, it is can absorb circuit surge current, was played
Protective effect is pressed, and in overvoltage protection diode D5Both ends 0.1 μ F capacitor C in parallel3, play filter action；Two pole
Pipe rectifier bridge D1~D4It is made of 4 rectifier diode 1N4007, constitutes rectifier bridge stack by connection type as shown in the figure, can prevent
Reverse power connection, so that the transmitter power supply wiring direction can arbitrarily exchange；In addition it is also necessary to which the remote terminal in transmitter accesses
+ 24V DC external power supply and load resistance RL, constitute complete two-wire system output loop 6.In the effect of+24V DC power supply potential
Under, electric charge stream is via the external power supply in output loop (6), 9014 parallel connection of diode rectifier bridge, XTR105 and driving triode
Circuit, load resistance RL, to form a current signal transmission channel, 4 finally are flowed through in the current signal transmission channel
~20mA current signal ,+24V DC external power supply is internal work by the current signal transmission channel in output loop (6) simultaneously
Make loop power supply.
As shown in Fig. 2, the common mode resistance-capacitance network 8 is by 1 potentiometer RCM=2k Ω and 1 capacitor CCM=0.1 μ F is in parallel
The constant pressure source and constant-current source of the exciting current return terminal and V/I conversion circuit 5 that constitute, and be connected on Hall sensor 2 return
Reference ground between, V/I conversion circuit 5 export 1.6mA constant-current source flow through common mode resistance-capacitance network 8, so as to by adjusting
Potentiometer RCMResistance value provide common-mode voltage appropriate within the scope of 0~3.2V, and C for the work of differential amplifierCMThis can be filtered out
The ripple of common-mode voltage.
In addition, in embodiments, in constant pressure source VCCThe C of parallel connection as shown in Figure 2 is gone back between reference ground GND1=
10μF、C2=0.1 capacitor of μ F two, to filter out the stability that ripple improves voltage source.
Although the embodiment of the invention patent has been disclosed as above, not only in the description and the implementation
Listed utilization.It can be applied to the field of various suitable the invention patent completely.For those skilled in the art
Other modifications may be easily implemented.Therefore without departing from the general concept defined in the claims and the equivalent scope, this hair
Bright patent is not limited to specific details and legend shown and described herein.
Claims (8)
1. a kind of two-wire system Hall-type RMS current transmitter, it is characterised in that: the transmitter mainly by C-shaped magnet ring (1), suddenly
That sensor (2), differential amplifier circuit (3), virtual value detecting circuit (4), V/I conversion circuit (5), two-wire system output loop
(6), bias-voltage generating circuit (7), common mode resistance-capacitance network (8) composition, are tested electric current ImAcross C-shaped magnet ring (1), hall sensing
Device (2) is installed in the air gap of C-shaped magnet ring (1), and the voltage output of Hall sensor (2) is connected to differential amplifier circuit (3)
Input terminal, the output of differential amplifier circuit (3) are connected to the input terminal of virtual value detecting circuit (4), virtual value detecting circuit (4)
Output be connected to the input terminals of V/I conversion circuit (5), the output of bias-voltage generating circuit (7) is connected to differential amplification electricity
The bias voltage input of road (3) and virtual value detecting circuit (4), the output of V/I conversion circuit (5) are connected to two-wire system output
Circuit (6), and the constant current source output terminal of V/I conversion circuit (5) is connected to the exciting current input terminal of Hall sensor (2), V/I
The constant pressure source output terminal of conversion circuit (5) is connected to differential amplifier circuit (3), virtual value detecting circuit (4) and bias voltage and generates
The power end of circuit (7), common mode resistance-capacitance network (8) connect the exciting current return terminal and V/I conversion circuit in Hall sensor (2)
(5) between the reference ground that constant pressure source and constant-current source returns.
2. a kind of two-wire system Hall-type RMS current transmitter according to claim 1, it is characterised in that: measurement process
In, pass through the tested electric current I of C-shaped magnet ring (1)mIt is generated and tested electric current I in magnet ringmThe directly proportional toroidal magnetic field of size, the magnetic
Field passes perpendicularly through Hall sensor (2), and Hall sensor (2) is passed through the exciting current provided by V/I conversion circuit (5), therefore
Voltage output end output and the tested electric current I of Hall sensor (2)mThe directly proportional weak voltage signals of instantaneous value, the voltage
Signal is input to virtual value detecting circuit (4) after differential amplifier circuit (3) amplify, and virtual value detecting circuit (4) will input
AC signal be converted to and tested electric current ImThe directly proportional d. c. voltage signal of virtual value, and be input to V/I conversion circuit
(5), the voltage signal of input is converted to 4~20mA current signal by V/I conversion circuit (5), and by two-wire system output loop (6)
Signal transmission is carried out, and the voltage signal of bias-voltage generating circuit (7) output is input to differential amplifier circuit (3) and virtual value
The bias voltage input of detecting circuit (4) provides syntype bias voltage appropriate for virtual value detection process, and V/I turns
Changing circuit (5) output constant current source is that Hall sensor (2) provide exciting current signal, and the constant-current source is from Hall sensor (2)
The pressure drop for passing through common mode resistance-capacitance network (8) after the outflow of exciting current return terminal and generating is that differential amplifier circuit (3) offer is suitable
When input common mode voltage, V/I conversion circuit (5) export constant pressure source be differential amplifier circuit (3), virtual value detecting circuit (4)
And bias-voltage generating circuit (7) provides working power.
3. a kind of two-wire system Hall-type RMS current transmitter according to claim 1, it is characterised in that: described differential
Amplifying circuit (3) mainly by high-precision, micro energy lose instrument amplifier AD627 form, the virtual value detecting circuit (4) mainly by
Accurate micro energy lose rms detector LTC1966 composition, the difference voltage signal of Hall sensor (2) output are connected to AD627's
Differential input end, and the output offset side of AD627 accesses the bias voltage generated by bias-voltage generating circuit (7), AD627
No. 1 between No. 8 feet insertion gain adjust potentiometer, which can be used for the adjustment of transmitter measuring range, AD627's
Output is connected to the normal phase input end of LTC1966, and the bias voltage of bias-voltage generating circuit (7) output accesses simultaneously
The inverting input terminal and output offset side, the bias voltage of LTC1966 provides common mode operation voltage appropriate for LTC1966, together
When LTC1966 output end and output offset side between and access detection period capacitor.
4. a kind of two-wire system Hall-type RMS current transmitter according to claim 1, it is characterised in that: the V/I
Conversion circuit (5) is mainly made of voltage/current transformation chip XTR105, and input voltage is linearly converted to 4~20mA
Electric current is exported, and the DC voltage of virtual value detecting circuit (4) output is input to the normal phase input end of XTR105, and V/I
The voltage-regulating circuit in series by 2 fixed resistances and 1 potentiometer, potentiometer center are connected in conversion circuit (5)
Tap is connected to the inverting input terminal of XTR105, and the adjustment voltage of potentiometer centre cap output can provide appropriate total for XTR105
Mould operating voltage, and can be used for the adjustment of transmitter measurement zero point, in addition, the amplification factor tune for thering is fixed resistance to be connected to XTR105
Whole end, the resistance determine the voltage/current conversion coefficient of XTR105, meanwhile, XTR105 exports 2 road 0.8mA constant-current sources, by 2
Hall sensor (2) are input to after road constant-current source is in parallel, as the excitation current source of Hall sensor (2), which also exports 1
The constant pressure source of road 5.1V, 1mA capacity generates electricity as differential amplifier circuit (3), virtual value detecting circuit (4) and bias voltage
The working power on road (7).
5. a kind of two-wire system Hall-type RMS current transmitter according to claim 1, it is characterised in that: the biasing
Voltage generation circuit (7) is made of 2 followers that divider resistance and low consumed power operational amplifier MAX4480 are constituted of connecting, and 2
A series resistance connects between the 5.1V voltage source that V/I conversion circuit (5) generate, and series connection point is connected to the positive input of MAX4480
End, inverting input terminal are connected with output end, generate 1.6V bias voltage in output end.
6. a kind of two-wire system Hall-type RMS current transmitter according to claim 1, differential put it is characterized in that: described
The total power consumption of big circuit (3), virtual value detecting circuit (4) and bias-voltage generating circuit (7) is extremely low, and transmitter internal work returns
The total current on road is less than 4mA, so as to realize that with 4mA be the two-wire system electric current output for measuring zero point.
7. a kind of two-wire system Hall-type RMS current transmitter according to claim 1, it is characterized in that: the two-wire system
Output loop (6) is mainly by NPN type driving triode, overvoltage protection diode, diode rectifier bridge, load resistance and external electricity
Source forms, and the diode rectifier bridge in circuit has reverse connecting protection effect, and it is defeated that external power supply can access two-wire system by any direction
Circuit (6) out are exported and are transmitted by two-wire system output loop (6) 4~20mA current signal, while supplying for internal work circuit
Electricity.
8. a kind of two-wire system Hall-type RMS current transmitter according to claim 1, it is characterised in that: the common mode
Resistance-capacitance network (8) is made of 1 potentiometer and 1 capacitor parallel connection, and the exciting current for being connected on Hall sensor (2) returns
Between the reference ground that the constant pressure source and constant-current source of end and V/I conversion circuit (5) return, V/I conversion circuit (5) output
1.6mA constant-current source flows through common mode resistance-capacitance network (8), so as to mention by adjusting the work that the resistance value of potentiometer is differential amplifier
For common-mode voltage appropriate, and capacitor can filter out the ripple of the common-mode voltage.
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| CN201910571276.8A CN110187158A (en) | 2019-06-26 | 2019-06-26 | A kind of two-wire system Hall-type RMS current transmitter |
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| CN201910571276.8A CN110187158A (en) | 2019-06-26 | 2019-06-26 | A kind of two-wire system Hall-type RMS current transmitter |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110912399A (en) * | 2019-12-11 | 2020-03-24 | 国网山东省电力公司济南供电公司 | Time domain power supply system of temperature sensor |
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