CN105067868A - Current measuring method and device - Google Patents
Current measuring method and device Download PDFInfo
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- CN105067868A CN105067868A CN201510588803.8A CN201510588803A CN105067868A CN 105067868 A CN105067868 A CN 105067868A CN 201510588803 A CN201510588803 A CN 201510588803A CN 105067868 A CN105067868 A CN 105067868A
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Abstract
The invention provides a current measuring method and a current measuring device, which relate to the field of electronic circuits. The current measuring method comprises the steps of: adjusting a first auxiliary current, so that the sum of intensity of a magnetic field generated by the first auxiliary current flowing through an auxiliary coil of an auxiliary current and intensity of a magnetic field generated by a current to be detected is a first magnetic field intensity; acquiring value of the first auxiliary current; switching on a second auxiliary current, wherein direction of magnetic field intensity generated by the second auxiliary current is opposite to direction of magnetic field intensity generated by the first auxiliary current; adjusting the second auxiliary current, so that the sum of intensity of a magnetic field generated by the secondary auxiliary current flowing through the auxiliary coil of the auxiliary current and intensity of the magnetic field generated by the current to be detected is a second magnetic field intensity, and the first magnetic field intensity and the second magnetic field intensity are identical in magnitude and opposite in direction; acquiring value of the second auxiliary current; and carrying out differential operation on the second auxiliary current and the first auxiliary current, and calculating the current to be detected according to a difference value between the second auxiliary current and the first auxiliary current as well as number of turns of the auxiliary coil. The current measuring method can improve the measurement accuracy.
Description
Technical field
The present invention relates to electronic circuit field, in particular to a kind of current measuring method and device.
Background technology
In the systems such as modern industry control, instrument and meter, power electronic equipment, the non-contact detecting technology of electric current is the technology that of safeguards system safe operation is indispensable.Such as, in electrical power transmission system, system is after running for a long time, due to reasons such as aging, weather, the insulativity of its transfer wire must decline, and the minute leakage electric current now produced likely makes system miss operation or produces misoperation, is the huge hidden danger of system safety operation.Existing measuring technique as depicted in figs. 1 and 2, needs the current probe built when Fig. 1 shows the non-cpntact measurement of electric current.Current probe comprises magnetic loop, sensitive detection parts and ancillary coil.Magnetic loop is made up of soft magnetic material.This magnetic loop can be one, also can be the parallel connection of multiple magnetic loop.Can not comprise air gap in this magnetic loop, also can comprise one or more air gap, and magnetic loop can be close-shaped arbitrarily.
When utilizing magnetosensitive device to detect, sensitive detection parts embed the Hall element, mistor etc. in magnetic loop air gap; When utilizing magnetic modulation principle to detect, sensitive detection parts are exactly that one or more groups is wrapped in coil in magnetic loop, need peripheral circuit by coil to magnetic circuit ceaselessly excitation during the detection of this class, and after producing interact with D.C. magnetic field, just can produce detectable electrical quantities.
Ancillary coil can be one group, also can be many groups.Electric current to be measured generally adopts the frame mode of single turn core, but also can adopt the mode that multiturn is wound around.
Current probe only regards one as can be converted into the device that can detect electrical quantities by current value to be measured for outside, and has nothing to do with the detection mode which kind of current probe adopts concrete.
Fig. 2 is the circuit theory schematic diagram that the one extensively adopted at present is called " Zero flux " survey control technology.The electric current to be measured of case of external is I, and adopt the structure of single turn core, the number of turn of ancillary coil is N.
The signal that first current probe detects by circuit carry out amplification process, then by this amplified signal to the electric current I on ancillary coil
acontrol, the electric current I on ancillary coil
athe magnetic field that outside electric current I to be measured produces must be offset in the magnetic field produced.Whole like this circuit just constitutes a feedback loop, according to profound and negative feedbck principle, as long as loop gain is enough large, and electric current I on ancillary coil
athe magnetic field produced just equals the magnetic field that outside electric current I to be measured produces, magnetic core always works in " Zero flux state " state, ancillary coil electric current I
ahave: I
a=-I/N.
Direction of current in above formula is determined according to the label direction of electric current in Fig. 2.Like this, according to the electric current I on ancillary coil
a, namely circuit can complete the measurement to outside electric current I.
A bit, " Zero flux " survey control technology of above discussion, can also expand to widely " permanent magnetic flux " control technology: when the theory structure of Fig. 2 is constant to supplementary notes, by ancillary coil electric current I
acarry out controlling, make the electric current I on ancillary coil
athe magnetic field sum that the magnetic field produced and outside electric current I to be measured produces is always a steady state value, that is:
I
A×N+I＝H
0
I
A＝H
0/N-I/N
Wherein H
0represent a constant magnetic field intensity, also can represent a constant electric current, the measurement to outside electric current I to be measured can be completed equally, and a special case of " Zero flux " technology just " permanent magnetic flux " control technology.
Prior art shown in Fig. 1 and Fig. 2 easily produces the stability problem exporting zero point because of magnetic material behavior and circuit characteristic two aspect, i.e. " zero point drift " problem.Practical application as measurement at small area analysis time, this phenomenon has become the basic reason of restriction Related product measuring accuracy.
Summary of the invention
In view of this, the invention provides a kind of current measuring method, on the basis of existing detection method, propose and in magnetic loop, produce the direction in magnetic field by changing electric current in ancillary coil, realize the method that current signal to be measured presents with difference component form.The method compared with prior art, significantly can reduce the zero point drift of testing result, improves measuring accuracy.
For achieving the above object, the invention provides following technical scheme:
A kind of current measuring method, the circuit of electric current to be measured and the circuit of auxiliary current are all wound in same magnetic loop, and described auxiliary current comprises the first auxiliary current and the second auxiliary current, and described method comprises:
Regulate described first auxiliary current, the magnetic field intensity sum that the magnetic field intensity that described first auxiliary current is produced by the ancillary coil of described auxiliary current and described electric current to be measured produce is the first magnetic field intensity;
Obtain the value of described first auxiliary current under described first magnetic field intensity;
Second auxiliary current described in conducting, described second auxiliary current produce magnetic field intensity direction and described first auxiliary current to produce the direction of magnetic field intensity contrary;
Regulate described second auxiliary current, it is the second magnetic field intensity that the magnetic field intensity that described second auxiliary current is produced by the ancillary coil of described auxiliary current and described electric current to be measured produce magnetic field intensity sum, and described second magnetic field intensity is equal with described first magnitude of field intensity, direction is contrary;
Obtain the value of described second auxiliary current under described second magnetic field intensity;
Described second auxiliary current and described first auxiliary current are done calculus of differences, electric current to be measured according to the difference of described second auxiliary current and the first auxiliary current and described ancillary coil turns calculations.
Preferably, in above-mentioned current measuring method, one group of control signal can be produced with a chopper signal generator, periodically alternately fragment will be divided into the time.
Preferably, in above-mentioned current measuring method, the signal that described chopper signal generator produces is in order to control described link control module, alternately change the connection topological structure between described ancillary coil and described ancillary coil current control module, thus the first auxiliary current described in alternate conduction and described second auxiliary current, and the magnetization direction that described second auxiliary current is produced in magnetic loop is contrary with the magnetization direction that described first auxiliary current produces in magnetic loop.
Preferably, in above-mentioned current measuring method, in the regular hour fragment that chopping signal divides, by the control of described chopper signal generator to described link control module, described input amplification module, described ancillary coil current control module and described ancillary coil form the feedback loop of the first topological structure by magnetic loop, described ancillary coil current control module automatically regulates described first auxiliary current under negative feedback state, the magnetic field intensity sum that the magnetic field intensity that described first auxiliary current is produced by the ancillary coil of described auxiliary current and described electric current to be measured produce is the first magnetic field intensity, and obtain the value of described first auxiliary current when magnetic field intensity is described first magnetic field intensity.
Preferably, in above-mentioned current measuring method, in the other regular hour fragment that chopping signal divides, by the control of described chopper signal generator to described link control module, described input amplification module, described ancillary coil current control module and described ancillary coil form the feedback loop of the second topological structure by magnetic loop, described ancillary coil current control module automatically regulates described second auxiliary current under negative feedback state, the magnetic field intensity sum that the magnetic field intensity that described second auxiliary current is produced by the ancillary coil of described auxiliary current and described electric current to be measured produce is the second magnetic field intensity, and obtain the value of described second auxiliary current when magnetic field intensity is described second magnetic field intensity.
Preferably, in above-mentioned current measuring method, described second magnetic field intensity is identical with described first magnitude of field intensity, direction contrary, and its size can artificially set in circuit, can be zero, also can be non-vanishing.
Preferably, in above-mentioned current measuring method, described second auxiliary current signal and described first auxiliary current signal are done calculus of differences, more described electric current to be measured can be calculated according to the described ancillary coil number of turn.
If only use an ancillary coil, can by described link control module under the control of described chopping signal, connection topological structure between the output terminal changing described ancillary coil circuit and described ancillary coil control module, make described first auxiliary current by the ancillary coil of described auxiliary current produce magnetic field intensity direction and described second auxiliary current by the ancillary coil of described auxiliary current to produce the direction of magnetic field intensity contrary, the change of this topology connection structure refers to by described link control module, make to present Opposite direction connection relation between the port of the port of described ancillary coil and described ancillary coil current control module output current.Also the ancillary coil that many group winding directions are different can be used, by described link control module under the control of described chopping signal, the different ancillary coil of choice for use make described first auxiliary current by the ancillary coil of described auxiliary current produce magnetic field intensity direction and described second auxiliary current by the ancillary coil of described auxiliary current to produce the direction of magnetic field intensity contrary, the now change of topology connection structure refers to by described link control module, the port of described ancillary coil current control module output current connects from different ancillary coils.Particularly, use any method make described first auxiliary current by the ancillary coil of described auxiliary current produce magnetic field intensity direction and described second auxiliary current by the ancillary coil of described auxiliary current to produce the direction of magnetic field intensity contrary, all can be considered the change of topology connection structure.
Preferably, in above-mentioned current measuring method, described first auxiliary current is I
a, the ancillary coil number of turn of described auxiliary current is N, and described electric current to be measured is I, and described first magnetic field intensity is H
0, described I
a, N, I, H
0meet formula I
a× N+I=H
0.
By the form of symbol and expression formula, the relation of the ancillary coil number of turn of the first auxiliary current, auxiliary current, electric current to be measured, the first magnetic field intensity is showed, more simple and clear.
Preferably, in above-mentioned current measuring method, described second auxiliary current is I
b, the ancillary coil number of turn of described auxiliary current is N, and described electric current to be measured is I, and described second magnetic field intensity is-H
0, described I
b, N, I, H
0meet formula-I
b× N+I=-H
0.
By the form of symbol and expression formula, the relation of the ancillary coil number of turn of the second auxiliary current, auxiliary current, electric current to be measured, the second magnetic field intensity is showed, more simple and clear.
Preferably, in above-mentioned current measuring method, described first auxiliary current is I
a, the second auxiliary current is I
b, the ancillary coil number of turn of described auxiliary current is N, and described electric current to be measured is I, and described first magnetic field intensity is H
0, described second magnetic field intensity is-H
0, electric current to be measured according to the difference of described second auxiliary current and the first auxiliary current and described ancillary coil turns calculations, comprises according to formula I
b-I
a=2I/N calculates described electric current to be measured.
Above-mentioned expression formula clearly reflects when described electric current to be measured measured by needs, only need know the ancillary coil number of turn of the first auxiliary current, the second auxiliary current and auxiliary current, described first magnetic field intensity, the second magnetic field intensity can be eliminated on the impact of measuring.
Present invention also offers a kind of current measuring device, adopt above-mentioned current measuring method, described device comprises: chopper signal generator, input amplification module, ancillary coil current control module, link control module, gating control module, the first state keep module, the second state keeps module and calculus of differences module; Current circuit to be measured and ancillary coil are wound in same magnetic loop.
Described input amplification module is for detecting the magnetic field intensity signal in magnetic loop, and testing result is converted into electrical signal and amplifies, then is transferred to described ancillary coil current control module; Described ancillary coil current control module is connected with described ancillary coil by described link control module, described ancillary coil current control module can under negative feedback automatic regulation output size of current, thus regulate the electric current in described ancillary coil; Described gating control module is connected with described ancillary coil current control module, in order to transmit current value signals in described ancillary coil; Described first state keeps module to keep module to be connected with described gating control module, in order to keep ancillary coil current value signals with described second state; Described calculus of differences module and described first state keep module and described second state to keep model calling, keep holding signal in module to do calculus of differences in order to described first state to be kept module and described second state.
Described chopper signal generator, in order to produce one group of control signal, will be divided into periodically alternately fragment the time; The signal that described chopper signal generator produces is in order to control linkage control module, alternately change the connection topological structure between described ancillary coil and described ancillary coil current control module, thus the first auxiliary current described in alternate conduction and described second auxiliary current, and the magnetization direction that described second auxiliary current is produced in magnetic loop is contrary with the magnetization direction that described first auxiliary current produces in magnetic loop.
Divide in regular hour fragment in chopping signal, by the control of described chopper signal generator to described link control module, described input amplification module, described ancillary coil current control module and described ancillary coil form the feedback loop of the first topological structure by magnetic loop, described ancillary coil current control module automatically regulates described first auxiliary current under negative feedback state, the magnetic field intensity sum that the magnetic field intensity that described first auxiliary current is produced by the ancillary coil of described auxiliary current and described electric current to be measured produce is the first magnetic field intensity, and obtain the value of described first auxiliary current when magnetic field intensity is described first magnetic field intensity.
In the other regular hour fragment that chopping signal divides, by the control of described chopper signal generator to described link control module, described input amplification module, described ancillary coil current control module and ancillary coil form the feedback loop of the second topological structure by magnetic loop, described ancillary coil current control module automatically regulates described second auxiliary current under negative feedback state, the magnetic field intensity sum that the magnetic field intensity that described second auxiliary current is produced by the ancillary coil of described auxiliary current and described electric current to be measured produce is the second magnetic field intensity, and obtain the value of described second auxiliary current when magnetic field intensity is described second magnetic field intensity.
Described second magnetic field intensity is equal with described first magnitude of field intensity, direction is contrary, and its size artificially sets in circuit, can be zero, also can be non-vanishing.
Described gating control module be used for described copped wave generator institute produce the control of signal under, respectively the signal of the value of obtained described first auxiliary current and described second auxiliary current signal are delivered to described first state keep module and the second state maintenance module keep.
Described first auxiliary current signal that described calculus of differences module is used for described first state being kept module and described second state to keep keeping in module and described second auxiliary current signal do calculus of differences, electric current to be measured according to the difference of described second auxiliary current signal and the first auxiliary current signal and described ancillary coil turns calculations.
The present invention on the basis of existing detection method, propose by change electric current in ancillary coil in magnetic loop produce the direction in magnetic field, realize the method that current signal to be measured presents with difference component form.The method compared with prior art, significantly can reduce the zero point drift of testing result, improves measuring accuracy.
Accompanying drawing explanation
In order to the clearer explanation embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is the schematic diagram of existing current probe structure;
Fig. 2 is the structural representation of existing current measuring method;
Fig. 3 is the structural representation after improving existing current measuring method;
Fig. 4 is the process flow diagram of the current measuring method that the embodiment of the present invention provides;
Fig. 5 is the structural representation of the current measuring device that one embodiment of the invention provides;
Fig. 6 is the structural representation of the current measuring device that another embodiment of the present invention provides.
Embodiment
Existing measuring technique easily produces the stability problem exporting zero point because of magnetic material behavior and circuit characteristic two aspect, i.e. " zero point drift " problem, affects measuring accuracy.
In view of the foregoing, researcher is through long-term research and a large amount of practices, provide a kind of current measuring method, on the basis of existing detection method, propose by change electric current in ancillary coil in magnetic loop produce the direction in magnetic field, realize the method that current signal to be measured presents with difference component form.The method compared with prior art, significantly can reduce the zero point drift of testing result, improves measuring accuracy.
Below in conjunction with accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Below to the detailed description of the embodiments of the invention provided in the accompanying drawings and the claimed scope of the present invention of not intended to be limiting, but only represent selected embodiment of the present invention.Based on embodiments of the invention, the every other embodiment that those skilled in the art obtain under the prerequisite not making creative work, all belongs to the scope of protection of the invention.
Please refer to Fig. 3, Fig. 3 shows the structural representation after improving existing current measuring method (referring to Fig. 2).As shown in Figure 3, ancillary coil 170 is allowed to carry out Opposite direction connection with the output port of former control circuit.And remaining circuit, current probe and circuit connecting mode remain unchanged.
Same employing " permanent magnetic flux " negative feedback control technology, to now ancillary coil electric current I
bcontrol, make the electric current I on ancillary coil
bthe magnetic field sum that the magnetic field produced and outside electric current I to be measured produces is-H
0.Namely allow magnetic field at this moment magnetic loop and original equal and opposite in direction, direction is contrary.
Now ancillary coil " oppositely " connects, its electric current I
bthe magnetic fields direction produced, with original contrary, can obtain:
-I
B×N+I＝-H
0
I
B＝H
0/N+I/N
By I
b=H
0/ N+I/N and I
a=H
0/ N-I/N carries out calculus of differences, then have:
I
B-I
A＝2I/N
Namely the measurement to electric current I to be measured can be completed.
Above-mentioned I
abe specifically as follows the first auxiliary current, above-mentioned I
bbe specifically as follows the second auxiliary current.
Refer to Fig. 4, Fig. 4 shows a kind of current measuring method provided by the invention, the method can be applied to the field of current measurement of non-direct contact, and the non-contact detecting technology of electric current ensures one of the system safety operation such as Industry Control, instrument and meter, power electronic equipment indispensable technology.The method needs to build a magnetic loop, and the circuit of electric current to be measured and the circuit of auxiliary current are all wound in this magnetic loop.Described auxiliary current comprises the first auxiliary current and the second auxiliary current.Described electric current to be measured can be DC current, described auxiliary current is the electric current flowing through ancillary coil, the value of two auxiliary currents corresponding respectively under recording two contrary magnetic field intensitys of equal and opposite in direction, direction respectively, just can draw the value of electric current to be measured according to the above-mentioned value of two auxiliary currents and the turns calculations of ancillary coil.Described current measuring method can comprise the following steps S101 to S106.
Step S101, regulates described first auxiliary current, and the magnetic field intensity sum that the magnetic field intensity that described first auxiliary current is produced by the ancillary coil 170 of described auxiliary current and described electric current to be measured produce is the first magnetic field intensity.
Can by electricity parameter as the numerical value such as voltage, electric current reflect as described in the size of the first magnetic field intensity, even can be reflected the size of described first magnetic field intensity by the numerical value of the pointer of equipment etc.Pointer value and first magnetic field intensity of electricity parameter or equipment have specific corresponding relation, but above-mentioned numerical value can not be the concrete numerical value of the first magnetic field intensity.
Step S102, obtains the value of described first auxiliary current under described first magnetic field intensity.
The value of described first auxiliary current specifically can be obtained by modes such as circuit negative feedback control, device measurings.It is limitation of the present invention that the mode obtaining the value of described first auxiliary current should not be construed.The value of described first auxiliary current also can represent with other electricity parameter.
Step S103, the second auxiliary current described in conducting, described second auxiliary current produce magnetic field intensity direction and described first auxiliary current to produce the direction of magnetic field intensity contrary.
Such as, the second auxiliary current described in conducting can be carried out by chopper signal generator 121 (see Fig. 5) control to link control module 110.Specifically can change by link control module 110 (see Fig. 5) magnetization direction that electric current produced by the ancillary coil 170 of described auxiliary current, obtain with described first auxiliary current produce the second contrary auxiliary current of magnetization direction, it is limitation of the present invention that the mode in the direction of magnetic field intensity that change electric current produces should not be construed.
Step S104, regulate described second auxiliary current, it is the second magnetic field intensity that the magnetic field intensity that described second auxiliary current is produced by the ancillary coil 170 of described auxiliary current and described electric current to be measured produce magnetic field intensity sum, and described second magnetic field intensity is equal with described first magnitude of field intensity, direction is contrary.
Can by electricity parameter as the numerical value such as voltage, electric current reflect as described in the size of the second magnetic field intensity, even can be reflected the size of described second magnetic field intensity by the numerical value of the pointer of equipment etc.Pointer value and second magnetic field intensity of electricity parameter or equipment have specific corresponding relation, but above-mentioned numerical value can not be the concrete numerical value of the second magnetic field intensity.
Step S105, obtains under the second magnetic field intensity, the value of described second auxiliary current.
The value of described second auxiliary current specifically can be obtained by modes such as circuit negative feedback control, device measurings.It is limitation of the present invention that the mode obtaining the value of described second auxiliary current should not be construed.The value of the second auxiliary current also can represent with other electricity parameter.
Step S106, does calculus of differences by described second auxiliary current and described first auxiliary current, electric current to be measured according to the difference of described second auxiliary current and the first auxiliary current and described ancillary coil turns calculations.
Described first auxiliary current can be I
a, ancillary coil 170 number of turn of described auxiliary current can be N, and described electric current to be measured can be I, and described first magnetic field intensity can be H
0, product and the described electric current sum to be measured of ancillary coil 170 number of turn of described first auxiliary current and described auxiliary current are the first magnetic field intensity, specifically can be expressed as formula I
a× N+I=H
0.
Described second auxiliary current can be I
b, because the equal and opposite in direction of described second magnetic field intensity and described first magnetic field intensity, direction are contrary, therefore described second magnetic field intensity specifically can be expressed as-H
0, product and the described electric current sum to be measured of ancillary coil 170 number of turn of described second auxiliary current and described auxiliary current are the second magnetic field intensity, specifically can be expressed as formula-I
b× N+I=-H
0.
I
a× N+I=H
0i can be deformed into
a=H
0/ N-I/N ,-I
b× n+I=-H
0i can be deformed into
b=H
0/ N+I/N.Described second auxiliary current and described first auxiliary current are done calculus of differences, specifically can obtain I
b-I
a=2I/N.Therefore, described first magnetic field intensity and the second magnetic field intensity can being eliminated on the impact of measuring, when learning the value of described first auxiliary current and the second auxiliary current and the described ancillary coil number of turn, the value of electric current I to be measured can be obtained.
The ancillary coil flow through due to the first auxiliary current under described first magnetic field intensity and the second auxiliary current under the second magnetic field intensity is same winding, or for being wound in the different windings of same magnetic loop, therefore the error produced because of magnetic material behavior and circuit characteristic can be reduced greatly.
Fig. 5 shows the current measuring device that one embodiment of the invention provides.Comprise chopper signal generator 121, input amplification module 180, link control module 110, ancillary coil current control module 122, gating control module 130, calculus of differences module 150, first state keeps module 140 and the second state to keep module 160.Current circuit to be measured and ancillary coil 170 are wound in same magnetic loop.
Described input amplification module 180 is for detecting the magnetic field intensity signal in magnetic loop, and testing result is converted into electrical signal and amplifies, then is transferred to described ancillary coil current control module 122; Described ancillary coil current control module 122 is connected with described ancillary coil 170 by described link control module 110, described ancillary coil current control module 122 can under negative feedback automatic regulation output size of current, thus regulate the electric current in described ancillary coil 170; Described gating control module 130 is connected with described ancillary coil current control module 122, in order to transmit current value signals in described ancillary coil 170; Described first state keeps module 140 to keep module 160 to be connected with described gating control module 130, in order to keep ancillary coil current value signals with described second state; Described calculus of differences module 150 and described first state keep module 140 and described second state to keep module 160 to be connected, and keep the signal kept in module 160 to do calculus of differences in order to described first state to be kept module 140 and described second state.
Described chopper signal generator 121, in order to produce one group of control signal, will be divided into periodically alternately fragment the time, in order to control described link control module 110 and gating control module 130; Specifically can be designated as A time slice and B time slice respectively, A time slice is the fragment that one group of time span is equal, B time slice is the fragment that another group time span is equal, and the time span of described A time slice can be equal with the time span of described B time slice, also can be unequal.
The signal that described chopper signal generator 121 produces, in order to control linkage control module 110, changes the connection topological structure between described ancillary coil 170 and described ancillary coil current control module 122; Particularly, in A time slice, the connection topological structure between described ancillary coil 170 and described ancillary coil current control module 122 is the first state, and in described ancillary coil 170, the electric current of institute's conducting is described first auxiliary current; In B time slice, the connection topological structure between described ancillary coil 170 and described ancillary coil current control module 122 is the second state, and in described ancillary coil 170, the electric current of institute's conducting is described second auxiliary current; The magnetization direction that described second auxiliary current produces in magnetic loop is contrary with the magnetization direction that described first auxiliary current produces in magnetic loop.
In A time slice, by the control of described chopper signal generator 121 to described link control module 110, described input amplification module 180, described ancillary coil current control module 122 and described ancillary coil 170 form the feedback loop of the first topological structure by magnetic loop, described ancillary coil current control module 122 automatically regulates described first auxiliary current under negative feedback state, the magnetic field intensity sum that the magnetic field intensity that described first auxiliary current is produced by the ancillary coil 170 of described auxiliary current and described electric current to be measured produce is the first magnetic field intensity, the signal of described first auxiliary electrical flow valuve when now can to obtain magnetic field intensity be described first magnetic field intensity.
In B time slice, by the control of described chopper signal generator 121 to described link control module 110, described input amplification module 180, described ancillary coil current control module 122 and described ancillary coil 170 form the feedback loop of the second topological structure by magnetic loop, described ancillary coil current control module 122 automatically regulates described second auxiliary current under negative feedback state, the magnetic field intensity sum that the magnetic field intensity that described second auxiliary current is produced by the ancillary coil 170 of described auxiliary current and described electric current to be measured produce is the second magnetic field intensity, the signal of described second auxiliary electrical flow valuve when now can to obtain magnetic field intensity be described second magnetic field intensity.
Described second magnetic field intensity is equal with described first magnitude of field intensity, direction is contrary, and its size artificially sets in circuit, can be zero, also can be non-vanishing.
Described gating control module 130 for described chopper signal generator 121 produce the control of signal under, keep module 140 and the second state to keep module 160 to keep to described first state the signal of obtained described first auxiliary electrical flow valuve and the signal transmission of described second auxiliary electrical flow valuve respectively; Particularly, in A time slice, the Signal transmissions of the described first auxiliary electrical flow valuve obtained keeps module 140 to keep to described first state by described gating control module 130; In B time slice, the Signal transmissions of the described second auxiliary electrical flow valuve obtained keeps module 160 to keep to described second state by described gating control module 130.
Described calculus of differences module 150 is for doing calculus of differences, electric current to be measured according to described second auxiliary current signal and the difference of the first auxiliary current signal and the turns calculations of described ancillary coil 170 by described first auxiliary current signal kept in described first state maintenance module 140 and described second state maintenance module 160 and described second auxiliary current signal.
Fig. 6 shows the structured flowchart of the current measuring device that another embodiment of the present invention provides.This embodiment comprises link control module 110, chopper signal generator 121, gating control module 130, first state amplification maintenance module 141, first state ancillary coil current module 142, calculus of differences module 150, second state amplification maintenance module 161, second state ancillary coil current module 162, input amplification module 180 and ancillary coil electric current gating module 210.
Described chopper signal generator 121 for generation of one group of control signal, for controlling described link control module 110, gating control module 130 and ancillary coil electric current gating module 210.Its objective is and the time will be divided into fragment, specifically can be designated as A time slice and B time slice respectively, A time slice is the fragment that one group of time span is equal, B time slice is the fragment that another group time span is equal, the time span of described A time slice can be equal with the time span of described B time slice, also can be unequal.
In different time slices, the signal produced by described chopper signal generator 121 is to the control of described link control module 110, gating control module 130 and ancillary coil electric current gating module 210, allow circuit present two kinds of Topology connection states, specifically can be designated as the first state and the second state respectively.
Particularly, chopper signal generator 121 produces the first control signal in A time slice, makes circuit be in the first state, produces the second control signal in B time slice, makes circuit be in the second state.
Described input amplification module 180 for detecting the signal in magnetic loop, and passes to described gating control module 130 after being amplified by signal.
Described gating control module 130 is under the signal control of described chopper signal generator 121, the output signal of described input amplification module 180 is delivered in A time slice described first state and amplifies maintenance module 141, in B time slice, be delivered to described second state amplify maintenance module 161.
Described first state amplifies maintenance module 141 and the amplification of the second state keeps module 161 to amplify for carrying out to the received signal and keep.In A time slice, the first state is amplified the output signal of maintenance module 141 to the described input amplification module 180 that the transmission of described gating control module 130 is come and is amplified, and the second state amplification keeps the original output signal of module 161 maintenance constant; In B time slice, the second state is amplified the output signal of maintenance module 161 to the described input amplification module 180 that the transmission of described gating control module 130 is come and is amplified, and the first state amplification keeps the original output signal of module 141 maintenance constant.
Described first state ancillary coil current module 142 and the second state ancillary coil current module 162 export for realizing electric current.First state ancillary coil current module 142 keeps the output signal of module 141 to be converted to the output of corresponding electric current for described first state being amplified, and electric current is specifically as follows the first auxiliary current; Second state ancillary coil current module 162 keeps the output signal of module 161 to be converted to the output of corresponding electric current for described second state being amplified, and electric current is specifically as follows the second auxiliary current.
Described ancillary coil electric current gating module 210 is under the signal control of described chopper signal generator 121, the electric current that described first state ancillary coil current module 142 and the second state ancillary coil current module 162 export is delivered to described link control module 110 by A, B time slice, and is input in ancillary coil 170 via after described link control module 110.In A time slice, the output current of the first state ancillary coil current module 142 is delivered to described link control module 110 by described ancillary coil electric current gating module 210 gating; In B time slice, the output current of the second state ancillary coil current module 162 is delivered to described link control module 110 by described ancillary coil electric current gating module 210 gating.
Described link control module 110 is under the signal control of described chopper signal generator 121, change the topology connection structure of ancillary coil 170 and ancillary coil electric current gating module 210, the magnetization direction that the electric current in ancillary coil 170 is produced in magnetic loop is contrary in A, B time slice.Particularly, the magnetization direction that described first auxiliary current is produced by described ancillary coil 170 in A time slice is contrary with the magnetization direction that the second auxiliary current described in B time slice is produced by described ancillary coil 170.
In A time segment, described input amplification module 180, described first state amplify maintenance module 141, described first state ancillary coil current module 142 and described ancillary coil 170, be connected with described link control module 110 by described gating control module 130, described ancillary coil electric current gating module 210, formed the feedback loop of the first topological structure by magnetic loop; Under negative feedback, described first auxiliary current that described first state ancillary coil current module 142 exports regulates automatically, and the magnetic field intensity sum that the magnetic field intensity that described first auxiliary current is produced by the ancillary coil 170 of described auxiliary current and described electric current to be measured produce is the first magnetic field intensity; Described first auxiliary current value signal when now can to obtain magnetic field intensity be described first magnetic field intensity.
In B time segment, described input amplification module 180, described second state amplify maintenance module 161, described second state ancillary coil current module 162 and described ancillary coil 170, be connected with described link control module 110 by described gating control module 130, described ancillary coil electric current gating module 210, form the second topological structure feedback loop by magnetic loop; Under negative feedback, described second auxiliary current that described second state ancillary coil current module 162 exports regulates automatically, and the magnetic field intensity sum that the magnetic field intensity that described second auxiliary current is produced by the ancillary coil 170 of described auxiliary current and described electric current to be measured produce is the second magnetic field intensity; Described second auxiliary current value signal when now can to obtain magnetic field intensity be described second magnetic field intensity.
Described second magnetic field intensity is equal with described first magnitude of field intensity, direction is contrary, and its size artificially sets in circuit, can be zero, also can be non-vanishing.
Described calculus of differences module 150 for described second auxiliary current value signal and described first auxiliary current value signal are carried out calculus of differences, electric current to be measured according to described second auxiliary current value signal and the difference of the first auxiliary current value signal and the turns calculations of described ancillary coil 170.
The present invention on the basis of existing detection method, propose by change electric current in ancillary coil in magnetic loop produce the direction in magnetic field, realize the method that current signal to be measured presents with difference component form.The method compared with prior art, significantly can reduce the zero point drift of testing result, improves measuring accuracy.
The essence of this kind of measuring technique is magnetic field detection, as long as therefore magnetic field to be measured is equivalent to the electric current to be measured in literary composition, the technology of the present invention principle can be applied to magnetic-field measurement equally.
For making the object of the embodiment of the present invention, technical scheme and advantage clearly, above in conjunction with the accompanying drawing in the embodiment of the present invention, carry out describing clearly and completely to the technical scheme in the embodiment of the present invention, obviously, described embodiment is the present invention's part embodiment, instead of whole embodiments.The assembly of the embodiment of the present invention describing and illustrate in usual accompanying drawing herein can be arranged with various different configuration and design.
Therefore, the detailed description of the above embodiments of the invention to providing in the accompanying drawings the claimed scope of the present invention of not intended to be limiting, but only represent selected embodiment of the present invention.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
It should be noted that: represent similar terms in similar label and letter accompanying drawing below, therefore, once be defined in an a certain Xiang Yi accompanying drawing, then do not need to define further it and explain in accompanying drawing subsequently.
In describing the invention, it should be noted that, term " " center ", " on ", D score, " left side ", " right side ", " vertically ", " level ", " interior ", orientation or the position relationship of the instruction such as " outward " are based on orientation shown in the drawings or position relationship, or this invention product orientation of usually putting or position relationship when using, only the present invention for convenience of description and simplified characterization, instead of indicate or imply that the device of indication or element must have specific orientation, with specific azimuth configuration and operation, therefore limitation of the present invention can not be interpreted as.In addition, term " first ", " second ", " the 3rd " etc. only for distinguishing description, and can not be interpreted as instruction or hint relative importance.
In describing the invention, also it should be noted that, unless otherwise clearly defined and limited, term " setting ", " installation ", " being connected ", " difference ", " connection " should be interpreted broadly, such as, " connection " can be fixedly connected with, and also can be removably connect, or connect integratedly; Can be mechanical connection, also can be electrical connection; Can be directly be connected, also indirectly can be connected by intermediary, can be the connection of two element internals; Again such as, " difference " computing can be completed by the device with subtraction character, also can be completed by the device with addition property.For the ordinary skill in the art, concrete condition above-mentioned term concrete meaning in the present invention can be understood.
Claims (10)
1. a current measuring method, is characterized in that, the circuit of electric current to be measured and the circuit of auxiliary current are all wound in same magnetic loop, and described auxiliary current comprises the first auxiliary current and the second auxiliary current, and described method comprises:
Regulate described first auxiliary current, the magnetic field intensity sum that the magnetic field intensity that described first auxiliary current is produced by the ancillary coil of described auxiliary current and described electric current to be measured produce is the first magnetic field intensity;
Obtain the value of described first auxiliary current under described first magnetic field intensity;
Second auxiliary current described in conducting, described second auxiliary current produce magnetic field intensity direction and described first auxiliary current to produce the direction of magnetic field intensity contrary;
Regulate described second auxiliary current, it is the second magnetic field intensity that the magnetic field intensity that described second auxiliary current is produced by the ancillary coil of described auxiliary current and described electric current to be measured produce magnetic field intensity sum, and described second magnetic field intensity is equal with described first magnitude of field intensity, direction is contrary;
Obtain the value of described second auxiliary current under described second magnetic field intensity;
Described second auxiliary current and described first auxiliary current are done calculus of differences, electric current to be measured according to the difference of described second auxiliary current and the first auxiliary current and described ancillary coil turns calculations.
2. current measuring method according to claim 1, is characterized in that, comprises a chopper signal generator, produces one group of control signal, will be divided into periodically alternately fragment the time; The signal that described chopper signal generator produces is in order to control linkage control module, alternately change the connection topological structure between described ancillary coil and described ancillary coil current control module, thus the first auxiliary current described in alternate conduction and described second auxiliary current, and the magnetization direction that described second auxiliary current is produced in magnetic loop is contrary with the magnetization direction that described first auxiliary current produces in magnetic loop; The signal that described chopper signal generator produces is also in order to control gating control module.
3. current measuring method according to claim 1, it is characterized in that, by described chopper signal generator, circuit is connected to the control of topological structure, input amplification module, the topology connection structure of the feedback loop that ancillary coil current control module and ancillary coil are formed by magnetic loop alternately changes, thus alternately to make described first auxiliary current produce magnetic field intensity sum by the magnetic field intensity that ancillary coil produces of described auxiliary current and described electric current to be measured be described first magnetic field intensity, it is described second magnetic field intensity that described second auxiliary current produces magnetic field intensity sum by the magnetic field intensity that ancillary coil produces of described auxiliary current and described electric current to be measured, and the value of described first auxiliary current when alternately to obtain magnetic field intensity be described first magnetic field intensity, the value of described second auxiliary current when magnetic field intensity is described second magnetic field intensity.
4. current measuring method according to claim 1, is characterized in that, described second magnetic field intensity is identical with described first magnitude of field intensity, direction is contrary.
5. current measuring method according to claim 1, it is characterized in that, the signal produced by described chopper signal generator is to the control of gating control module, the signal of the value of described first auxiliary current when alternately making obtained magnetic field intensity be described first magnetic field intensity is transferred to the first state by described gating control module and keeps module to keep, and the signal of the value of described second auxiliary current when magnetic field intensity is described second magnetic field intensity is transferred to the second state by described gating control module and keeps module to keep.
6. current measuring method according to claim 1, it is characterized in that, the first auxiliary current signal that described calculus of differences module is used for described first state being kept module and described second state to keep keeping in module and described second auxiliary current signal do calculus of differences, electric current to be measured according to the difference of described second auxiliary current signal and the first auxiliary current signal and described ancillary coil turns calculations.
7. current measuring method according to claim 1, is characterized in that, described first auxiliary current is I
a, the ancillary coil number of turn of described auxiliary current is N, and described electric current to be measured is I, and described first magnetic field intensity is H
0, described I
a, N, I, H
0meet formula I
a× N+I=H
0.
8. current measuring method according to claim 1, is characterized in that, described second auxiliary current is I
b, the ancillary coil number of turn of described auxiliary current is N, and described electric current to be measured is I, and described second magnetic field intensity is-H
0, described I
b, N, I, H
0meet formula-I
b× N+I=-H
0.
9. current measuring method according to claim 1, is characterized in that, described first auxiliary current is I
a, the second auxiliary current is I
b, the ancillary coil number of turn of described auxiliary current is N, and described electric current to be measured is I, and described first magnetic field intensity is H
0, described second magnetic field intensity is-H
0, electric current to be measured according to the difference of described second auxiliary current and the first auxiliary current and described ancillary coil turns calculations, comprises according to formula I
b-I
a=2I/N calculates described electric current to be measured.
10. a current measuring device, it is characterized in that, described device comprises: chopper signal generator, input amplification module, ancillary coil current control module, link control module, gating control module, the first state keep module, the second state keeps module and calculus of differences module; Current circuit to be measured and ancillary coil are wound in same magnetic loop;
Described input amplification module is for detecting the magnetic field intensity signal in magnetic loop, and testing result is converted into electrical signal and amplifies, then is transferred to described ancillary coil current control module; Described ancillary coil current control module is connected with described ancillary coil by described link control module, described ancillary coil current control module can under negative feedback automatic regulation output size of current, thus regulate the electric current in described ancillary coil; Described gating control module is connected with described ancillary coil current control module, in order to transmit current value signals in ancillary coil; Described first state keeps module to keep module to be connected with described gating control module, in order to keep ancillary coil current value signals with described second state; Described calculus of differences module and described first state keep module and described second state to keep model calling, keep holding signal in module to do calculus of differences in order to described first state to be kept module and described second state;
Described chopper signal generator, in order to produce one group of control signal, will be divided into periodically alternately fragment the time; The signal that described chopper signal generator produces is in order to control linkage control module, alternately change the connection topological structure between described ancillary coil and described ancillary coil current control module, thus the first auxiliary current described in alternate conduction and described second auxiliary current, and the magnetization direction that described second auxiliary current is produced in magnetic loop is contrary with the magnetization direction that described first auxiliary current produces in magnetic loop;
Divide in regular hour fragment in chopping signal, by the control of described chopper signal generator to described link control module, described input amplification module, described ancillary coil current control module and described ancillary coil form the feedback loop of the first topological structure by magnetic loop, described ancillary coil current control module automatically regulates described first auxiliary current under negative feedback state, the magnetic field intensity sum that the magnetic field intensity that described first auxiliary current is produced by the ancillary coil of described auxiliary current and described electric current to be measured produce is the first magnetic field intensity, and obtain the value of described first auxiliary current when magnetic field intensity is described first magnetic field intensity,
In the other regular hour fragment that chopping signal divides, by the control of described chopper signal generator to described link control module, described input amplification module, described ancillary coil current control module and ancillary coil form the feedback loop of the second topological structure by magnetic loop, described ancillary coil current control module automatically regulates described second auxiliary current under negative feedback state, the magnetic field intensity sum that the magnetic field intensity that described second auxiliary current is produced by the ancillary coil of described auxiliary current and described electric current to be measured produce is the second magnetic field intensity, and obtain the value of described second auxiliary current when magnetic field intensity is described second magnetic field intensity,
Described second magnetic field intensity is equal with described first magnitude of field intensity, direction is contrary;
Described gating control module be used for described copped wave generator institute produce the control of signal under, respectively the signal of the value of obtained described first auxiliary current and described second auxiliary current signal are delivered to described first state keep module and the second state maintenance module keep;
Described first auxiliary current signal that described calculus of differences module is used for described first state being kept module and described second state to keep keeping in module and described second auxiliary current signal do calculus of differences, electric current to be measured according to the difference of described second auxiliary current signal and the first auxiliary current signal and described ancillary coil turns calculations.
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