A kind of closed-loop current sensorsTechnical field
The present invention relates to current sensing techniques field, and in particular to a kind of closed-loop current sensors.
Background technology
Current sensor is widely used in the neck such as new energy, intelligent transportation, Industry Control, intelligent appliance and intelligent gridDomain.Conventional current sensor is divided into open loop type and the major class of closed loop two.Open loop type current sensor is around tested wireOne magnetic core with air gap is set, and magnetic transducing unit is located in air gap, and due to the law of electromagnetic induction, magnetic core produces electricity of inductingGesture, the magnetic field at the measurable magnetic core air gap of magnetic transducing unit, rear end can calculate according to the output signal of magnetic transducing unitThe size of tested electric current.The working method of open loop type current sense is direct measurement magnetic field, therefore under high current effect, magnetic coreMagnetic hysteresis and saturation occurs, influence measurement accuracy.
In order to overcome above mentioned problem, those skilled in the art use closed loop current sensor measurement electric current.And open loop typeUnlike current sensor, bucking coil, bucking coil and magnetic transducing are wound with the magnetic core of closed loop current sensorUnit is electrically connected, and bucking coil is powered by the output voltage of magnetic transducing unit, to compensate magnetic field caused by tested electric current, whenWhen reaching magnetic balance, magnetic field caused by magnetic field caused by compensation electric current and tested electric current is roughly the same, therefore magnetic core generally worksIn the environment of without magnetic flux or magnetic flux very little, magnetic hysteresis and saturated phenomenon can be overcome.Rear end can pass through direct measurement compensating lineThe size of current of circle calculates tested size of current.
As shown in figure 1, Chinese patent literature (U of CN 203259575) discloses a kind of closed-loop current sensors, including setThere are the magnetism gathering rings of opening, the wire and bucking coil that electric current to be measured flows through are wound on magnetism gathering rings respectively, by being arranged on poly- magneticMagnetic field in the Hall element detection magnetism gathering rings of ring opening, when having detected magnetic field, control produces compensation electric current and flows through benefitRepay coil and then the magnetic field opposite with electric current to be measured is produced in magnetism gathering rings.
But, on the one hand, often size is larger for the magnetism gathering rings in above-mentioned closed-loop current sensors so that closed loop current sensesThe volume of device is larger, heavier-weight；On the other hand, the price as the magnetism gathering rings of magnetic core is often higher so that closed loop current passesThe cost of manufacture of sensor is higher.
The content of the invention
In view of this, the embodiments of the invention provide a kind of closed-loop current sensors, sensed with solving existing closed loop currentThe problem of body product is larger, heavier-weight, higher cost of manufacture.
The embodiments of the invention provide a kind of closed-loop current sensors, including：At least one bucking coil, it is arranged on to be measuredElectric current flows through the pre-position of wire, for producing the compensation magnetic field opposite with the magnetic field of the electric current to be measured；At least oneIndividual magnetic sensing chip, each magnetic sensing chip are arranged in the lumen of a bucking coil, for measuring the electricity to be measuredThe intensity in the superposition magnetic field in the magnetic field of stream and the compensation magnetic field；Control module, for the output according to the magnetic sensing chipThe electric current of signal output predefined size；The input of the control module is connected with the output end of the magnetic sensing chip, outputEnd is connected with one end of the bucking coil；IV modular converters, its input are connected with the other end of the bucking coil, and its is defeatedGo out output end of the end as the closed-loop current sensors；The IV modular converters change the current signal of the bucking coilFor voltage signal.
Alternatively, at least one bucking coil includes at least two bucking coils, in the lumen of each bucking coilOne magnetic sensing chip is set.
Alternatively, the magnetic sensing chip at least two bucking coils inner chamber is flowed through relative to the electric current to be measuredWire is symmetrical arranged.
Alternatively, the control module includes VI converting units；The VI converting units include：First operation amplifier listMember, output end of two input respectively with two magnetic sensing chips are connected, and output end is connected with the bucking coil.
Alternatively, described two bucking coil series connection, one end after series connection are connected with the output end of the control module, gone here and thereThe other end after connection is connected with the input of the IV modular converters.
Alternatively, the IV modular converters include：Second operational amplifier, its first input end and the bucking coilThe other end is connected, the second input connection reference voltage, and resistance is connected between first input end and output end.
Alternatively, the magnetic sensing chip includes：First series arm, include the first magneto-resistor and the second magnetoelectricity of series connectionResistance；Second series arm, including the 3rd magneto-resistor of series connection and the 4th magneto-resistor；First series arm and the described second stringJoin branch circuit parallel connection to set, the both ends connection power supply after parallel connection；The magnetic sensing chip also includes：3rd operation amplifier unit, itsFirst input end is connected between first magneto-resistor and second magneto-resistor, and its second input is connected to the described 3rdBetween magneto-resistor and the 4th magneto-resistor；The 3rd operation amplifier unit is put to the difference of two input end signalsGreatly.
Alternatively, one end of first magneto-resistor is connected with one end of the 3rd magneto-resistor, second magneto-resistorOne end be connected with one end of the 4th magneto-resistor；First magneto-resistor, second magneto-resistor, the 3rd magneto-resistorIt is equal with the initial resistance and magnetic responsivity of the 4th magneto-resistor；Also, first magneto-resistor and the 4th magnetoelectricityThe magnetic susceptibility direction of resistance is identical, and second magneto-resistor is identical with the magnetic susceptibility direction of the 3rd magneto-resistor.
Alternatively, the closed-loop current sensors also include printed circuit board, the control module and/or IV conversionsModule is arranged on the printed circuit board.
Alternatively, the bucking coil is fixed in the printed circuit board plane vertically by support.
The closed-loop current sensors that the embodiment of the present invention is provided, bucking coil is arranged on electric current to be measured and flows through wirePre-position, and magnetic sensing chip is set in the lumen of bucking coil, control module is according to the output of magnetic sensing chipThe current control bucking coil of signal output predefined size produces the compensation magnetic field opposite with the magnetic field of electric current to be measured, so as to reduceSuperposition magnetic field measured by magnetic sensing chip, it is consequently formed a closed loop configuration.Because the magnetic field in the lumen of bucking coil is strongDegree is more uniform, therefore the magnetic sensing chip of the closed-loop current sensors can relatively accurately be surveyed in the case of magnetic core is lackedThe intensity in amount superposition magnetic field.The relatively small closed-loop current sensors volume of magnetic core, lighter in weight, low manufacture cost are not used.
Brief description of the drawings
The features and advantages of the present invention can be more clearly understood by reference to accompanying drawing, accompanying drawing is schematically without that should manageSolve to carry out any restrictions to the present invention, in the accompanying drawings：
Fig. 1 shows the schematic diagram of closed-loop current sensors in the prior art；
Fig. 2 shows a kind of schematic diagram of closed-loop current sensors according to embodiments of the present invention；
Fig. 3 shows that electric current to be measured flows through the schematic top plan view in the precalculated position of wire；
Fig. 4 shows that electric current to be measured flows through the front view in the precalculated position of wire；
Fig. 5 shows the schematic diagram of another closed-loop current sensors according to embodiments of the present invention；
Fig. 6 shows the connection diagram of controller according to embodiments of the present invention；
Fig. 7 shows the schematic diagram of a magnetic sensing chip；
Fig. 8 shows the schematic diagram of another magnetic sensing chip；
Fig. 9 shows the complete structure front view of the closed-loop current sensors of the embodiment of the present invention；
Figure 10 respectively illustrates the complete structure top view of the closed-loop current sensors of the embodiment of the present invention.
Embodiment
To make the purpose, technical scheme and advantage of the embodiment of the present invention clearer, below in conjunction with the embodiment of the present inventionIn accompanying drawing, the technical scheme in the embodiment of the present invention is clearly and completely described, it is clear that described embodiment isPart of the embodiment of the present invention, rather than whole embodiments.Based on the embodiment in the present invention, those skilled in the art are not havingThere is the every other embodiment made and obtained under the premise of creative work, belong to the scope of protection of the invention.
Embodiment one
Fig. 2 shows a kind of schematic diagram of closed-loop current sensors according to embodiments of the present invention.As shown in Fig. 2 this is closedCircular current sensor includes at least one bucking coil 10, at least one magnetic sensing chip 20, control module 30 and IV moduluss of conversionBlock 40.The "×" in left side represents that electric current to be measured flows through that wire is vertical with paper in Fig. 2, and current direction is to penetrate paperDirection.
Bucking coil 10 is arranged on the pre-position that electric current to be measured flows through wire, for producing the magnetic with electric current to be measuredThe opposite compensation magnetic field in field.It is somebody's turn to do distance and orientation that " precalculated position " refers to flow through wire relative to electric current to be measured, Fig. 3 and figure4 give the situation in several precalculated positions.It is vertical with paper and electric that round dot in Fig. 3 represents that electric current to be measured flows through wireStream flow direction is to pass the direction of paper, and the dotted line in Fig. 3 and Fig. 4 represents the magnetic field of electric current to be measured.Bucking coil can be arranged atAny one or more positions shown in rhombus, pentagon or five-pointed star in Fig. 3 and Fig. 4.
Each magnetic sensing chip 20 is arranged in the lumen of a bucking coil 10, for measure electric current to be measured magnetic field andCompensate the intensity in the superposition magnetic field in magnetic field.As shown in Fig. 2 one or more magnetic sensing chips can be set in a bucking coil20。
Control module 30 is used for the electric current that predefined size is exported according to the output signal of magnetic sensing chip 20.Control module 30Input be connected with the output end of magnetic sensing chip 20, the output end of control module 30 is connected with one end of bucking coil 10.
The input of IV modular converters 40 is connected with the other end of bucking coil 10, the output end conduct of IV modular converters 40The output end of the closed-loop current sensors.The current signal of bucking coil 10 is converted to voltage signal by IV modular converters.
When the position of bucking coil is more than one, these bucking coils can be connected respectively with control module；OrPerson can also be the series connection of these bucking coils, be connected again with control module after series connection.
Control module 30 can include microprocessor, power supply and gate-controlled switch, and microprocessor receives magnetic sensor chip 20Output signal it is handled, then output control signal control gate-controlled switch realize to current value size in bucking coil 10Adjustment；Or control module 30 can also be VI converting units, and it is defeated that the output voltage of Magnetic Sensor 20 is converted into current signalEnter bucking coil.
Above-mentioned closed-loop current sensors, bucking coil is arranged on the pre-position that electric current to be measured flows through wire, andMagnetic sensing chip is set in the lumen of bucking coil, and control module exports predefined size according to the output signal of magnetic sensing chipCurrent control bucking coil produce the compensation magnetic field opposite with the magnetic field of electric current to be measured, the closed loop configuration enables to superposition magneticField remains zero.Because the intensity that magnetic field is compensated in the lumen of bucking coil is more uniform, therefore the closed-loop current sensorsMagnetic sensing chip can relatively accurately measure the intensity in superposition magnetic field in the case of magnetic core is lacked.The closed loop of magnetic core is not usedCurrent sensor volume is relatively small, lighter in weight, low manufacture cost.
Embodiment two
Fig. 5 shows the schematic diagram of another closed-loop current sensors according to embodiments of the present invention.As shown in figure 5, withThe difference of embodiment one is that the closed-loop current sensors include at least two bucking coils 11 and 12, two magnetic sensing chips21 and 22, control module 30, and IV modular converters 40.
Magnetic sensing chip 21 is arranged in the lumen of bucking coil 11, and magnetic sensing chip 22 is arranged at the chamber of bucking coil 12In pipe.Electric current to be measured flows through wire and is arranged between two bucking coils 21 and 22.
"×" in Fig. 5 represents that electric current to be measured flows through that wire is vertical with paper, and current direction is to penetrate paperDirection, BI1And BI2Represent the magnetic field of electric current to be measured, BC1And BC2Represent the magnetic field of bucking coil.Due to bucking coil 11 in Figure 5With 12 opening position, the magnetic direction that electric current to be measured flows through wire is opposite, therefore the coiling side of bucking coil 11 and 12To and connected mode need to ensure to pass to electric current when magnetic direction caused by bucking coil 11 and 12 be also opposite, so as toOffset the magnetic field of electric current to be measured.It should be added that the winding mode of bucking coil and connected mode be not in the applicationIt is limited to shown in Fig. 5.
Further, control module 30 includes VI converting units.As shown in fig. 6, VI converting units can be the first computingAmplifying unit 31, two inputs of the first operation amplifier unit 31 connect with the output end of two magnetic sensing chips 21 and 22 respectivelyConnect, output end is connected with bucking coil.The voltage signal that two magnetic sensing chips 21 and 22 export is changed into electricity by VI converting unitsFlow signal input offset coil.
Further, the magnetic sensing chip 22 in the magnetic sensing chip 21 and bucking coil 12 in the inner chamber of bucking coil 11Wire is flowed through relative to electric current to be measured to be symmetrical arranged.In the embodiment of the present invention, symmetrically arranged magnetic sensing chip has common modeThe effect of suppression, principle are as follows；By the electric current to be measured at the present position of Magnetic Sensor 21 and 22 flows through the magnetic field side of wireTo being opposite, if not current field to be measured is superimposed magnetic field zero with compensation magnetic field, then the direction in the superposition magnetic field should also be asIt is opposite.In dynamic changing process in measurement, it is assumed that the signal that at a time magnetic sensing chip 21 and 22 is exportedRespectively A and B, then the difference between the two is A-B.When electromagnetic interference be present in actual measuring environment, the usual He of magnetic sensing chip 21When the direction in the interference magnetic field of 22 opening positions is identical, namely the electromagnetic interference is common mode interference signal.Due to magnetic sensing chip 21Positional symmetry, structure with 22 is identical, thus common mode interference signal makes to change caused by the output valve of magnetic sensing chip 21 and 22Amount is identical, it is assumed that the variable quantity is C, then the output signal of magnetic sensing chip 21 and 22 is respectively then A+C and B+C, the twoDifference be still A-B.As can be seen here, common mode interference signal does not interfere with the output result of the first operation amplifier unit 31, namelyAbove-mentioned closed-loop current sensors have the function that common mode inhibition.
As a kind of optional embodiment of the present embodiment, two bucking coils 11 and 12 are connected, one end after series connection withThe output end connection of control module 30.
The other end after the input of IV conversion chips 40 is connected with bucking coil 11 and 12 is connected, IV conversion chips 40Output end of the output end as closed-loop current sensors.The current signal of bucking coil is converted to voltage letter by IV modular convertersNumber.
Alternatively, as shown in fig. 6, IV modular converters 40 include the second operational amplifier, the first of the second operational amplifierThe other end after input is connected with bucking coil 11 and 12 is connected, and the second input connection of the second operational amplifier is with reference to electricityPressure, and it is connected with resistance between the first input end of the second operational amplifier and output end.
As a kind of optional embodiment of the present embodiment, magnetic sensing chip 20 includes the first series arm and the second series connectionBranch road.Wherein, the first series arm includes the first magneto-resistor and the second magneto-resistor of series connection；Second series arm includes series connection3rd magneto-resistor and the 4th magneto-resistor.First series arm is arranged in parallel with the second series arm, the both ends connection electricity after parallel connectionSource.In addition, magnetic sensing chip 20 also includes the 3rd operation amplifier unit, its first input end is connected to the first magneto-resistor and secondBetween magneto-resistor, its second input is connected between the 3rd magneto-resistor and the 4th magneto-resistor；3rd operation amplifier unit is to twoThe difference of individual input end signal is amplified.
As shown in fig. 7, magnetic sensing chip 21 includes the first magneto-resistor R of series connection11With the second magneto-resistor R12, the of series connectionThree magneto-resistor R13With the 4th magneto-resistor R14, two branch circuit parallel connections after series connection, the both ends connection power supply after parallel connection.Magnetic senses corePiece 21 also includes the 3rd operational amplifier 15, and its first input end is connected to the first magneto-resistor R11With the second magneto-resistor R12Between,Second input is connected to the 3rd magneto-resistor R13With the 4th magneto-resistor R14Between.The structure of magnetic sensing chip 22 and magnetic sensing coreThe structure of piece 21 is similar, as shown in figure 8, will not be repeated here.
Can be that two magneto-resistors diagonally set are conventional, electric-resistance, in addition in four magneto-resistors in magnetic sensing chipTwo magneto-resistors are initial value and/or the equal magneto-resistor of magnetic responsivity.When the magnetic field of electric current to be measured and the magnetic of bucking coilWhen the superposition magnetic field of field is zero, the signal value that the series parallel structure of magneto-resistor is exported is 0, or steady state value (has common mode disturbancesSituation)；When being superimposed magnetic field one unit of increase, the series parallel structure institute output signal value increase more than one list of magneto-resistorPosition, therefore magnetic sensing chip can improve the accuracy and magnetic sensing chip of measurement using above-mentioned magneto-resistor series-parallel structureSensitiveness.
Further, one end of the first magneto-resistor is connected with one end of the 3rd magneto-resistor, one end of the second magneto-resistor and theOne end connection of four magneto-resistors.First magneto-resistor, the second magneto-resistor, the initial resistance and magnetic of the 3rd magneto-resistor and the 4th magneto-resistorSusceptibility is equal, also, the first magneto-resistor is identical with the magnetic susceptibility direction of the 4th magneto-resistor, the second magneto-resistor and the 3rd magnetoelectricityThe magnetic susceptibility direction of resistance is identical.This is designed to the standard that measurement is further improved on the basis of above-mentioned magneto-resistor series parallel structureThe sensitiveness of true property and magnetic sensing chip.
" magnetic susceptibility direction is identical " herein refer under unidirectional magnetic field, and the resistance value of magneto-resistor increases orReduce；" magnetic susceptibility is in opposite direction " refers under unidirectional magnetic field, the resistance value increase of a magneto-resistor, another magnetoelectricityThe resistance value of resistance reduces." magnetic responsivity " herein refer to when residing one unit of changes of magnetic field, the resistance value of magneto-resistorVariable quantity.
As shown in fig. 7, in magnetic sensing chip 21, the first magneto-resistor R11, the second magneto-resistor R12, the 3rd magneto-resistor R13With4th magneto-resistor R14Initial resistance and magnetic responsivity it is equal, also, the first magneto-resistor R11With the 4th magneto-resistor R14MagnetosensitiveIt is identical to feel direction, the second magneto-resistor R12With the 3rd magneto-resistor R13Magnetic susceptibility direction it is identical.The situation and magnetic of magnetic sensing chip 22Sensing chip 21 is similar, will not be repeated here.
Fig. 9 and Figure 10 respectively illustrates the complete structure front view and vertical view of the closed-loop current sensors of the embodiment of the present inventionFigure, wherein 50 be printed circuit board, control module 30 and/or IV modular converters 40 are arranged on the printed circuit board.Compensating lineCircle is wound on support, and support is fixed on the printed circuit board vertically.Because coil winding is in the outside of support, therefore radiateProperty is good.
In addition, 61 and 62 represent the shell schematic diagram of the closed-loop current sensors, the shell is annular, and 61 represent inner ringWall, 62 represent external annulus.During measurement, electric current to be measured flows through wire and passes through interior annular distance.
70 is are arranged at the quotation marks contact pin on printed circuit board 50, and contact pin 70 is exposed through the through hole on shell, in order toThe measurement signal of closed-loop current sensors is drawn.
It is to lead to it will be understood by those skilled in the art that realizing all or part of flow in above-described embodiment methodComputer program is crossed to instruct the hardware of correlation to complete, described program can be stored in a computer read/write memory mediumIn, the program is upon execution, it may include such as the flow of the embodiment of above-mentioned each method.Wherein, described storage medium can be magneticDish, CD, read-only memory (ROM) or random access memory (RAM) etc..
Although being described in conjunction with the accompanying embodiments of the invention, those skilled in the art can not depart from the present inventionSpirit and scope in the case of various modification can be adapted and modification, such modifications and variations are each fallen within by appended claims instituteWithin the scope of restriction.