A kind of closed-loop current sensors
Technical field
It the utility model is related 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 grid
Domain.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 wire
One 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 inducting
Gesture, 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 unit
The 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 core
Magnetic 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 type
Unlike current sensor, bucking coil, bucking coil and magnetic transducing are wound with the magnetic core of closed loop current sensor
Unit 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, when
When 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 works
In 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 line
The 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 set
There 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- magnetic
Magnetic 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 benefit
Repay 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 senses
The 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 passes
The cost of manufacture of sensor is higher.
The content of the invention
In view of this, the utility model embodiment provides a kind of closed-loop current sensors, to solve existing closed loop current
The problem of sensor bulk is larger, heavier-weight, higher cost of manufacture.
The utility model embodiment provides a kind of closed-loop current sensors, including:At least one bucking coil, is arranged on
Electric current to be measured 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;Extremely
A few magnetic sensing chip, each magnetic sensing chip are arranged in the lumen of a bucking coil, for measuring described treat
Survey the intensity in the magnetic field of electric current and the superposition magnetic field in the compensation magnetic field;Control module, for according to the magnetic sensing chip
Output signal exports the electric current of predefined size;The input of the control module is connected with the output end of the magnetic sensing chip,
Output end is connected with one end of the bucking coil;IV modular converters, its input are connected with the other end of the bucking coil,
Output end of its output end as the closed-loop current sensors;The IV modular converters are by the current signal of the bucking coil
Be converted to voltage signal.
Alternatively, at least one bucking coil includes at least two bucking coils, in the lumen of each bucking coil
One 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 measured
Wire is symmetrical arranged.
Alternatively, the control module includes VI converting units;The VI converting units include:First operation amplifier list
Member, 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 there
The 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 coil
The 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 connection
Resistance;Second series arm, including the 3rd magneto-resistor of series connection and the 4th magneto-resistor;First series arm and the described second string
Join 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, its
First input end is connected between first magneto-resistor and second magneto-resistor, and its second input is connected to the described 3rd
Between magneto-resistor and the 4th magneto-resistor;The 3rd operation amplifier unit is put to the difference of two input end signals
Greatly.
Alternatively, one end of first magneto-resistor is connected with one end of the 3rd magneto-resistor, second magneto-resistor
One end be connected with one end of the 4th magneto-resistor;First magneto-resistor, second magneto-resistor, the 3rd magneto-resistor
It is equal with the initial resistance and magnetic responsivity of the 4th magneto-resistor;Also, first magneto-resistor and the 4th magnetoelectricity
The 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 conversions
Module 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 utility model embodiment is provided, bucking coil is arranged on electric current to be measured and flowed through
The pre-position of wire, and magnetic sensing chip is set in the lumen of bucking coil, control module is according to magnetic sensing chip
The current control bucking coil of output signal output predefined size produces the compensation magnetic field opposite with the magnetic field of electric current to be measured, so as to
Reduce the superposition magnetic field measured by magnetic sensing chip, be consequently formed a closed loop configuration.Due to the magnetic in the lumen of bucking coil
Field intensity is more uniform, therefore the magnetic sensing chip of the closed-loop current sensors can be more accurate in the case of magnetic core is lacked
The intensity in ground measurement superposition magnetic field.The relatively small closed-loop current sensors volume of magnetic core, lighter in weight, cost of manufacture are not used
It is low.
Brief description of the drawings
Feature and advantage of the present utility model can be more clearly understood by reference to accompanying drawing, accompanying drawing be schematically without
It is interpreted as carrying out any restrictions to the utility model, 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 the utility model embodiment;
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 the utility model embodiment;
Fig. 6 shows the connection diagram of the controller according to the utility model embodiment;
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 utility model embodiment;
Figure 10 respectively illustrates the complete structure top view of the closed-loop current sensors of the utility model embodiment.
Embodiment
It is new below in conjunction with this practicality to make the purpose, technical scheme and advantage of the utility model embodiment clearer
Accompanying drawing in type embodiment, the technical scheme in the embodiment of the utility model is clearly and completely described, it is clear that is retouched
The embodiment stated is the utility model part of the embodiment, rather than whole embodiments.Based on the implementation in the utility model
Example, the every other embodiment that those skilled in the art are obtained under the premise of creative work is not made, belongs to this reality
With novel protected scope.
Embodiment one
Fig. 2 shows a kind of schematic diagram of closed-loop current sensors according to the utility model embodiment.As shown in Fig. 2
The closed-loop current sensors turn including at least one bucking coil 10, at least one magnetic sensing chip 20, control module 30 and IV
Change the mold block 40.It is vertical with paper to represent that electric current to be measured flows through wire for the "×" in left side in Fig. 2, and current direction is to penetrate paper
The direction in face.
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 measured
The 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 figure
4 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 wire
Stream 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 at
Any 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 and
Compensate 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 coil
20。
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 30
Input 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 40
The 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;Or
Person 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 20
Output signal it is handled, then output control signal control gate-controlled switch realize to current value size in bucking coil 10
Adjustment;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 signal
Enter 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, and
Magnetic sensing chip is set in the lumen of bucking coil, and control module exports predefined size according to the output signal of magnetic sensing chip
Current 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 magnetic
Field remains zero.Because the intensity that magnetic field is compensated in the lumen of bucking coil is more uniform, therefore the closed-loop current sensors
Magnetic 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 used
Current 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 the utility model embodiment.Such as Fig. 5 institutes
Show, the difference with embodiment one is, the closed-loop current sensors include at least two bucking coils 11 and 12, two magnetic sensings
Chip 21 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 12
In 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 paper
Direction, 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 5
With 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 12
To 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 to
Offset 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 application
It 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 computing
Amplifying unit 31, two inputs of the first operation amplifier unit 31 connect with the output end of two magnetic sensing chips 21 and 22 respectively
Connect, 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 units
Flow 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 11
Wire is flowed through relative to electric current to be measured to be symmetrical arranged.In the utility model embodiment, symmetrically arranged magnetic sensing chip has
The effect of common mode inhibition, 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 of wire
Field direction is 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 be opposite.In dynamic changing process in measurement, it is assumed that at a time magnetic sensing chip 21 and 22 is exported
Signal is respectively A and B, then the difference between the two is A-B.When electromagnetic interference be present in actual measuring environment, usual magnetic sensing chip
21 it is identical with the direction in the interference magnetic field of 22 opening positions when, namely the electromagnetic interference is common mode interference signal.Because magnetic senses core
Piece 21 with 22 positional symmetry, structure it is identical, thus common mode interference signal makes caused by the output valve of magnetic sensing chip 21 and 22
Variable quantity 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 difference between the two is 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,
Namely above-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 with
The 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 40
Output end of the output end as closed-loop current sensors.The current signal of bucking coil is converted to voltage letter by IV modular converters
Number.
Alternatively, as shown in fig. 6, IV modular converters 40 include the second operational amplifier, the first of the second operational amplifier
The 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 electricity
Pressure, 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 connection
Branch road.Wherein, the first series arm includes the first magneto-resistor and the second magneto-resistor of series connection;Second series arm includes series connection
3rd 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 connection
Source.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 second
Between magneto-resistor, its second input is connected between the 3rd magneto-resistor and the 4th magneto-resistor;3rd operation amplifier unit is to two
The 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 connection
Three 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 core
Piece 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 core
The 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 chip
Two 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 coil
When 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 disturbances
Situation);When being superimposed magnetic field one unit of increase, the series parallel structure institute output signal value increase more than one list of magneto-resistor
Position, therefore magnetic sensing chip can improve the accuracy and magnetic sensing chip of measurement using above-mentioned magneto-resistor series-parallel structure
Sensitiveness.
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 the
One 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-resistor
Susceptibility 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 magnetoelectricity
The 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 structure
The 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 or
Reduce;" magnetic susceptibility is in opposite direction " refers under unidirectional magnetic field, the resistance value increase of a magneto-resistor, another magnetoelectricity
The resistance value of resistance reduces." magnetic responsivity " herein refer to when residing one unit of changes of magnetic field, the resistance value of magneto-resistor
Variable 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 R13With
4th magneto-resistor R14Initial resistance and magnetic responsivity it is equal, also, the first magneto-resistor R11With the 4th magneto-resistor R14Magnetosensitive
It 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 22
Sensing chip 21 is similar, will not be repeated here.
Fig. 9 and Figure 10 respectively illustrate the closed-loop current sensors of the utility model embodiment complete structure front view and
Top view, wherein 50 be printed circuit board, control module 30 and/or IV modular converters 40 are arranged on the printed circuit board.Mend
Coil winding is repaid on support, support is fixed on the printed circuit board vertically.Because coil winding is in the outside of support, therefore
Thermal diffusivity 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 ring
Wall, 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 to
The 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 method
Computer program is crossed to instruct the hardware of correlation to complete, described program can be stored in a computer read/write memory medium
In, 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 magnetic
Dish, CD, read-only memory (ROM) or random access memory (RAM) etc..
Although being described in conjunction with the accompanying embodiment of the present utility model, those skilled in the art can not depart from this
Various modification can be adapted in the case of the spirit and scope of utility model and modification, and such modifications and variations are each fallen within by appended power
Profit is required within limited range.