CN109270325A - A kind of self-excitation type open loop fluxgate current sensor circuit and its self-oscillation method - Google Patents
A kind of self-excitation type open loop fluxgate current sensor circuit and its self-oscillation method Download PDFInfo
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- CN109270325A CN109270325A CN201811337994.0A CN201811337994A CN109270325A CN 109270325 A CN109270325 A CN 109270325A CN 201811337994 A CN201811337994 A CN 201811337994A CN 109270325 A CN109270325 A CN 109270325A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
- G01R15/202—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using Hall-effect devices
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Abstract
The present invention provides a kind of self-excitation type open loop fluxgate current sensor circuit and its self-oscillation method, and self-excitation type open loop fluxgate current sensor circuit includes: positive supply；Negative supply or the reference zero of setting；Self-maintained circuit；And differential filtering amplifying circuit, the output end of the differential filtering amplifying circuit are the voltage output end of the self-excitation type open loop fluxgate current sensor circuit.The present invention is based on magnetic field detection coil voltages or current average to detect, and shape amplification is filtered by the difference of doing to this voltage or electric current, final output one detects signal, the voltage of magnetic field detection coil or the voltage on current sampling resistor are the input quantity of differential filtering amplifying circuit, circuit of the present invention is simple and practical, performance is good, at low cost, and consistency is good.
Description
Technical field
The invention belongs to be galvanically isolated detection and sensory field, and in particular to a kind of self-excitation type open loop fluxgate current sense
Device circuit and its self-oscillation method.
Technical background
Sensor is a kind of detection device, can detect the relevant information of tested equipment, be transformed into electric signal according to certain rules
Or the information output of other required forms, it is required with transmission, processing, storage, display, record and the control etc. that meet information.
Fluxgate current sensor is sensitive because of its response time fast (being smaller than 1us), good temp characteristic (being less than 100PPM)
High (uA grades) are spent, direct current and alternating current can be measured simultaneously, and measurement range is wide (mA grades~kA grades a few), in high performance electric current
Fields of measurement has consequence.Current fluxgate current sensor product is mostly using integrated fluxgate control chip as base
Plinth design, price is higher, and domestic sensor manufacturer is then substantially without similar product (mainly magnetic material and technical reason).
Summary of the invention
The purpose of the present invention is to provide a kind of simple and practical, low price, high performance self-excitation type open loop magnetic flux gate current
Sensor circuit and its self-oscillation method.
The present invention provides a kind of self-excitation type open loop fluxgate current sensor circuit comprising:
Positive supply；Negative supply or the reference zero of setting；Self-maintained circuit, including the first H bridge switch pipe, the 2nd H bridge
Switching tube, the 3rd H bridge switch pipe, the 4th H bridge switch pipe, magnetic field detection coil and current-limiting resistance；Wherein the first H bridge switch
The source electrode of the source electrode of pipe and the 2nd H bridge switch pipe is connected and is connect with positive supply；The source electrode and the 4th H of 3rd H bridge switch pipe
The source electrode of bridge switch pipe connects and is connected to the reference zero of negative supply or setting by leakage resistance of rationing the power supply；First H bridge switch
The drain electrode of pipe is connected with the drain electrode of the 3rd H bridge switch pipe and tie point is the first tie point；The drain electrode of 2nd H bridge switch pipe and
The drain electrode connections of four H bridge switch pipes and tie point are the second tie point；Magnetic field detection coil is connected to the first tie point and second
Between tie point；The grid of first H bridge switch pipe and the grid of the 3rd H bridge switch pipe link together and connect with the second tie point
It is logical；The grid of 2nd H bridge switch pipe and the grid of the 4th H bridge switch pipe link together and the connection of the first tie point；And it is poor
Divide filter amplification circuit, is connect with first tie point or the magnetic field detection coil, the differential filtering amplifying circuit
The voltage output end of self-excitation type open loop fluxgate current sensor circuit described in output end.
Further, the differential filtering amplifying circuit includes operational amplifier, the first differential resistor, the second differential electrical
Resistance, third differential resistor, the 4th differential resistor, first integral capacitor and second integral capacitor；Wherein first differential resistor
It is connected between the first tie point and the reverse input end of operational amplifier, the second differential resistor and the series connection of the 4th differential resistor connect
It connects and is connected between the second tie point and the positive input of operational amplifier, third differential resistor and first integral capacitor are simultaneously
Connection is connected and is connected between the reverse input end of operational amplifier and the output end of operational amplifier, second integral capacitor one end
It is connected to the positive input of operational amplifier, the second integral capacitor other end connects the reference zero of negative supply or setting.
Further, the self-maintained circuit further includes the magnetic field detection coil electricity being connected in series with magnetic field detection coil
Sampling resistor is flowed, magnetic field detection coil and magnetic field detection coil current sampling resistor are connected in series in the first tie point and second and connect
Between contact.
Further, the differential filtering amplifying circuit includes operational amplifier, the first differential resistor, the second differential electrical
Resistance, third differential resistor, the 4th differential resistor, first integral capacitor and second integral capacitor；Wherein first differential resistor
One end is connected between magnetic field detection coil and magnetic field detection coil current sampling resistor, the first differential resistor other end and operation
The reverse input end of amplifier connects, the second differential resistor and the 4th differential resistor is connected in series and be connected to the second tie point with
Between the positive input of operational amplifier, third differential resistor and first integral capacitor are connected in parallel and are connected to operation amplifier
Between the reverse input end of device and the output end of operational amplifier, second integral capacitor one end is connected to the forward direction of operational amplifier
Input terminal, the second integral capacitor other end connect the reference zero of negative supply or setting.
Further, the first H bridge switch pipe and the 2nd H bridge switch pipe are p-type metal-oxide-semiconductor, the 3rd H bridge switch pipe and the
Four H bridge switch pipes are N-type metal-oxide-semiconductor.
The present invention provides a kind of self-oscillation method of self-excitation type open loop fluxgate current sensor circuit again, including as follows
Step:
Step 1: when being powered, it is assumed that the first H bridge switch pipe is first open-minded, when the first H bridge switch pipe is opened, the first connection
Point is high level；
Step 2: the high level of the first tie point is added to the grid of the 2nd H bridge switch pipe and the grid of the 4th H bridge switch pipe
On, keep the shutdown of the 2nd H bridge switch pipe and the 4th H bridge switch pipe open-minded, makes the second tie point low level；
Step 3: the low level of the second tie point acts on the grid of the first H bridge switch pipe and the grid of the 3rd H bridge switch pipe
Pole is opened the first H bridge switch pipe and is turned off with the 3rd H bridge switch pipe, namely establishing the first tie point at this time is high level, the
Two tie points are low level circuit state；
Step 4: the first tie point established is high level and the second tie point is that low level voltage can be added to magnetic field inspection
On test coil, the voltage on the first tie point and the second tie point can be such that the electric current on magnetic field detection coil constantly increases, at this time
Definition is positive current from the first tie point to the electric current of the second tie point, this electric current can flow through current-limiting resistance, make on current-limiting resistance
Voltage be also continuously increased, cause the voltage on the second tie point also constantly to increase；
Step 5: when the electric current on magnetic field detection coil is greater than a certain threshold values, magnetic field detection coil inductance saturation, electricity
Stream rises rapidly, and the voltage and the second tie point voltage on current-limiting resistance also and then rise rapidly；
Step 6: when the second tie point voltage is greater than a certain threshold values, the conducting of the 3rd H bridge switch pipe and the first H bridge switch
It is low level that pipe, which turns off the first tie point, this low-voltage acts on the grid of the 2nd H bridge switch pipe and the grid of the 4th H bridge switch pipe
Pole makes the conducting of the 2nd H bridge switch pipe and the shutdown of the 4th H bridge switch pipe, and the second tie point is high level, namely establishes the at this time
One tie point is low level, the circuit state that the second tie point is high level；At this moment the first tie point is that low level and second connect
Contact is that the voltage of high level can be added on magnetic field detection coil, and the voltage on the second tie point and the first tie point can make magnetic field
Electric current opposite direction in detection coil constantly increases, and being defined at this time from the second tie point to the electric current of the first tie point is negative electricity
Stream, this electric current can flow through current-limiting resistance, be continuously increased the voltage on current-limiting resistance also, lead to the voltage on the first tie point
Constantly increase；
Step 7: when the electric current on magnetic field detection coil is greater than a certain threshold values, magnetic field detection coil inductance saturation, electricity
Stream rises rapidly, and the voltage and the first tie point voltage on current-limiting resistance also and then rise rapidly；
Step 8: when the first tie point voltage is greater than a certain threshold values, the conducting of the 4th H bridge switch pipe and the 2nd H bridge switch
Pipe shutdown, the second tie point are low level, this low-voltage acts on the grid and the 3rd H bridge switch pipe of the first H bridge switch pipe
Grid makes the conducting of the first H bridge switch pipe and the shutdown of the 3rd H bridge switch pipe, and the first tie point is high level, namely is established at this time
First tie point is high level, and the second tie point is low level circuit state.
The present invention provides a kind of self-oscillation method of self-excitation type open loop fluxgate current sensor circuit again, including as follows
Step:
Step 1: when being powered, it is assumed that the first H bridge switch pipe is first open-minded, when the first H bridge switch pipe is opened, the first connection
Point is high level；
Step 2: the high level of the first tie point is added to the grid of the 2nd H bridge switch pipe and the grid of the 4th H bridge switch pipe
On, keep the shutdown of the 2nd H bridge switch pipe and the 4th H bridge switch pipe open-minded, makes the second tie point low level；
Step 3: the low level of the second tie point acts on the grid of the first H bridge switch pipe and the grid of the 3rd H bridge switch pipe
Pole is opened the first H bridge switch pipe and is turned off with the 3rd H bridge switch pipe, namely establishing the first tie point at this time is high level, the
Two tie points are low level circuit state；
Step 4: the first tie point established is high level and the second tie point is that low level voltage can be added to magnetic field inspection
On test coil and magnetic field detection coil current sampling resistor, the voltage on the first tie point and the second tie point can make magnetic field detection
Electric current on coil constantly increases, and being defined at this time from the first tie point to the electric current of the second tie point is positive current, this electric current meeting
Current-limiting resistance is flowed through, is continuously increased the voltage on current-limiting resistance also, the voltage on the second tie point is caused also constantly to increase；
Step 5: when the electric current on magnetic field detection coil is greater than a certain threshold values, magnetic field detection coil inductance saturation, electricity
Stream rises rapidly, and the voltage and the second tie point voltage on current-limiting resistance also and then rise rapidly；
Step 6: when the second tie point voltage is greater than a certain threshold values, the conducting of the 3rd H bridge switch pipe and the first H bridge switch
It is low level that pipe, which turns off the first tie point, this low-voltage acts on the grid of the 2nd H bridge switch pipe and the grid of the 4th H bridge switch pipe
Pole makes the conducting of the 2nd H bridge switch pipe and the shutdown of the 4th H bridge switch pipe, and the second tie point is high level, namely establishes the at this time
One tie point is low level, the circuit state that the second tie point is high level；At this moment the first tie point is that low level and second connect
Contact be high level voltage can be added on magnetic field detection coil and magnetic field detection coil current sampling resistor, the second tie point and
Voltage on first tie point can be such that the electric current opposite direction on magnetic field detection coil constantly increases, and be defined at this time from the second tie point
Electric current to the first tie point is negative current, this electric current can flow through current-limiting resistance, be continuously increased the voltage on current-limiting resistance also,
The voltage on the first tie point is caused also constantly to increase；
Step 7: when the electric current on magnetic field detection coil is greater than a certain threshold values, magnetic field detection coil inductance saturation, electricity
Stream rises rapidly, and the voltage and the first tie point voltage on current-limiting resistance also and then rise rapidly；
Step 8: when the first tie point voltage is greater than a certain threshold values, the conducting of the 4th H bridge switch pipe and the 2nd H bridge switch
Pipe shutdown, the second tie point are low level, this low-voltage acts on the grid and the 3rd H bridge switch pipe of the first H bridge switch pipe
Grid makes the conducting of the first H bridge switch pipe and the shutdown of the 3rd H bridge switch pipe, and the first tie point is high level, namely is established at this time
First tie point is high level, and the second tie point is low level circuit state.
The present invention is based on magnetic field detection coil voltages or current average to detect, and by making the difference to this voltage or electric current
Divide filter shape amplification, final output one detects signal, and the voltage of magnetic field detection coil or the voltage on current sampling resistor are difference
The input quantity of filter amplification circuit, circuit of the present invention is simple and practical, and performance is good, at low cost, and consistency is good.
Detailed description of the invention
Below by clearly understandable mode, preferred embodiment is described with reference to the drawings, the present invention is given furtherly
It is bright.
Fig. 1 is that self-excitation type open loop fluxgate current sensor circuit first embodiment of the present invention is based on coil voltage average value
Detection circuit；
Fig. 2 is that self-excitation type open loop fluxgate current sensor circuit second embodiment of the present invention is based on coil current average value
Detection circuit.
Specific embodiment
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, Detailed description of the invention will be compareed below
A specific embodiment of the invention.It should be evident that drawings in the following description are only some embodiments of the invention, for
For those of ordinary skill in the art, without creative efforts, it can also be obtained according to these attached drawings other
Attached drawing, and obtain other embodiments.
To make simplified form, part related to the present invention is only schematically shown in each figure, they are not represented
Its practical structures as product.In addition, there is identical structure or function in some figures so that simplified form is easy to understand
Component only symbolically depicts one of those, or has only marked one of those.Herein, "one" is not only indicated
" only this ", can also indicate the situation of " more than one ".
Technical solution of the present invention is discussed in detail with specific embodiment below.
The present invention discloses a kind of self-excitation type open loop fluxgate current sensor circuit, and the present invention is really based on magnetic field detection
The open loop fluxgate current sense of coil (being called magnetic spy head coil) self-excited oscillating type and the detection of coil voltage or current average
Device circuit.
The present invention is based on open loop fluxgate testing principle, it can be achieved that direct current or exchange are galvanically isolated detection, belong to electric current
Isolation detection and sensory field
It is as shown in Figure 1 the circuit diagram of self-excitation type open loop fluxgate current sensor circuit first embodiment of the present invention, this
Dual power supply or single supply power supply, self-excitation type open loop fluxgate electricity can be used in invention self-excitation type open loop fluxgate current sensor circuit
Flow sensor circuit includes: positive supply VCC (positive supply VCC is dual power supply or single supply), (negative supply is according to design for negative supply
Need, can have or not have) or the reference zero of setting, the self-maintained circuit that is connect with positive supply and with from exciting
Swing the differential filtering amplifying circuit of circuit connection, the output end self-excitation type open loop fluxgate current sense of differential filtering amplifying circuit
The voltage output end Vout of device circuit.
When self-excitation type open loop fluxgate current sensor circuit is equipped with negative supply, self-maintained circuit is arranged in positive supply
Between negative supply；When self-excitation type open loop fluxgate current sensor circuit is not provided with negative supply, self-maintained circuit is set
It sets between positive supply and the reference zero of setting.
Self-maintained circuit includes the first H bridge switch pipe Q1, the 2nd H bridge switch pipe Q2, the 3rd H bridge switch pipe Q3, the 4th H
Bridge switch pipe Q4, magnetic field detection coil LS and current-limiting resistance R1.
First H bridge switch pipe Q1, the 2nd H bridge switch pipe Q2, the 3rd H bridge switch pipe Q3, the 4th H bridge switch pipe Q4, magnetic field
Detection coil LS, current-limiting resistance R1 and differential filtering amplifying circuit, differential filtering amplifying circuit export the voltage of this circuit
Vout。
Wherein, the first H bridge switch pipe Q1 and the 2nd H bridge switch pipe Q2 is p-type metal-oxide-semiconductor, the 3rd H bridge switch pipe Q3 and the 4th
H bridge switch pipe Q4 is N-type metal-oxide-semiconductor；Magnetic field detection coil LS is a satiable inductor, and the magnetic material of coil inside is usually by those
The magnetic material composition of high initial magnetoconductivity, low saturation induction density, the satiable inductor refer to when the electricity in inductance
When stream is greater than a certain threshold values, inductance can be reduced rapidly, and electric current meeting rapid increase is expressed as inductance saturation.
First H bridge switch pipe Q1, the 2nd H bridge switch pipe Q2, the 3rd H bridge switch pipe Q3, the 4th H bridge switch pipe Q4, magnetic field
Detection coil LS and current-limiting resistance R1 forms self-maintained circuit.
Differential filtering amplifying circuit includes that operational amplifier U1, the first differential resistor R3, the second differential resistor R4, third are poor
Sub-resistance R5, the 4th differential resistor R6, first integral capacitor C1 and second integral capacitor C2, the operation of differential filtering amplifying circuit
The output end of amplifier U1 exports the voltage end Vout of this circuit.
In self-maintained circuit: the source electrode connection of the source electrode and the 2nd H bridge switch pipe Q2 of the first H bridge switch pipe Q1 is simultaneously equal
It is connect with positive supply VCC；The source electrode of 3rd H bridge switch pipe Q3 and the source electrode of the 4th H bridge switch pipe Q4 connect and by rationing the power supply
Leakage resistance R1 is connected to the reference zero of negative supply or setting；The drain electrode of first H bridge switch pipe Q1 is with the 3rd H bridge switch pipe Q3's
Drain electrode connection (tie point is A point shown in FIG. 1, i.e. the first tie point)；The drain electrode of 2nd H bridge switch pipe Q2 and the 4th H bridge are opened
Close the drain electrode connection of pipe Q4 (tie point is B point shown in FIG. 1, i.e. the second tie point)；Magnetic field detection coil LS is connected to the first H
The tie point of the drain electrode of the drain electrode and the 3rd H bridge switch pipe Q3 of bridge switch pipe Q1 and drain electrode and the 4th H of the 2nd H bridge switch pipe Q2
(i.e. magnetic field detection coil LS is connected between A point and B point, is implemented shown in Fig. 1 between the tie point of the drain electrode of bridge switch pipe Q4
Example)；The grid of first H bridge switch pipe Q1 and the grid of the 3rd H bridge switch pipe Q3 link together and with the second tie point (i.e. B
Point) connection (can directly be connected to, can also be connected to by resistance)；The grid of 2nd H bridge switch pipe Q2 and the 4th H bridge switch pipe Q4's
Grid links together and the first tie point (i.e. A point) connection (can directly be connected to, can also be connected to by resistance).
In differential filtering amplifying circuit, the first differential resistor R3 is connected to the first tie point (i.e. A point) and operation amplifier
Between the reverse input end of device U1, the second differential resistor R4 and the 4th differential resistor R6 are connected in series and are connected to the second tie point
Between (i.e. B point) and the positive input of operational amplifier U1, third differential resistor R5 and first integral capacitor C1 are connected in parallel
And it is connected between the reverse input end of operational amplifier U1 and the output end of operational amplifier U1, the one end second integral capacitor C2
It is connected to the positive input of operational amplifier U1, the second integral capacitor C2 other end connects the reference zero of negative supply or setting
Point.
It is illustrated in figure 2 the circuit diagram of self-excitation type open loop fluxgate current sensor circuit second embodiment of the present invention, the
The difference of two embodiments and above-mentioned first embodiment is: self-maintained circuit further includes being connected in series with magnetic field detection coil LS
Magnetic field detection coil current sampling resistor R2, magnetic field detection coil LS and magnetic field detection coil current sampling resistor R2 are connected in series
Between the first tie point (i.e. A point) and the second tie point (i.e. B point).
The difference of second embodiment and above-mentioned first embodiment is: the first differential resistor R3 mono- of differential filtering amplifying circuit
End be connected to magnetic field detection coil LS and magnetic field detection coil current sampling resistor R2 between, the first differential resistor R3 other end
It is connect with the reverse input end of operational amplifier U1.
The present invention also provides a kind of self-oscillation method of self-excitation type open loop fluxgate current sensor circuit, including it is as follows
Step:
When just powering on, the first H bridge switch pipe Q1, the 2nd H bridge switch pipe Q2, the 3rd H bridge switch pipe Q3 and the 4th H bridge are opened
One of H bridge switch pipe can certainly will be will cause and preferentially open (in Fig. 1 because of the not quite identical property of device parameters by closing pipe Q4
It can accelerate this opening process with differential resistor R3, R4, R5, R6 of subsequent amplification circuitry in Fig. 2)；
Step 1: when being powered, it is assumed that the first H bridge switch pipe Q1 first open (when being initially powered, the first H bridge switch pipe Q1, the
Two H bridge switch pipe Q2, the 3rd H bridge switch pipe Q3 and the 4th H bridge switch pipe Q4 can be bound to because of the not quite identical property of device parameters
Will cause one of H bridge switch pipe preferentially open (in Fig. 1 differential resistor R3, R4 of differential filtering amplifying circuit, R5,
R6 can accelerate this opening process)), when the first H bridge switch pipe Q1 is opened, the first tie point (i.e. A point) is high level；
Step 2: the high level of the first tie point (i.e. A point) is added to the grid of the 2nd H bridge switch pipe Q2 and the 4th H bridge is opened
On the grid for closing pipe Q4, keeps the 2nd H bridge switch pipe Q2 shutdown and the 4th H bridge switch pipe Q4 open-minded, make the second tie point (i.e. B point)
For low level；
Step 3: the low level of the second tie point (i.e. B point) acts on the grid and the 3rd H bridge of the first H bridge switch pipe Q1
The grid of switching tube Q3 is opened the first H bridge switch pipe Q1 and is turned off with the 3rd H bridge switch pipe Q3, namely establishes first at this time
Tie point (i.e. A point) is high level, the second tie point (i.e. B point) is low level circuit state；
Step 4: the first tie point (i.e. A point) established is high level and the second tie point (i.e. B point) is low level electricity
Pressure can be added on magnetic field detection coil LS (or on magnetic field detection coil LS and magnetic field detection coil current sampling resistor R2), due to
Magnetic field detection coil LS is an inductance element, and electric current cannot be mutated, therefore the first tie point (i.e. A point) and the second tie point (i.e. B
Point) on voltage the electric current on magnetic field detection coil LS can be made constantly to increase (defined at this time from the first tie point (i.e. A point) to
The electric current of two tie points (i.e. B point) is positive current), this electric current can flow through current-limiting resistance R1, make the voltage on current-limiting resistance R1
It is continuously increased, is also constantly increased so as to cause the second tie point (i.e. B point) voltage；
Step 5: when the electric current on magnetic field detection coil LS is greater than a certain threshold values, magnetic field detection coil LS inductance saturation,
Its electric current rises rapidly, and voltage and the second tie point (i.e. B point) voltage on current-limiting resistance R1 also and then rises rapidly；
Step 6: when the second tie point (i.e. B point) voltage is greater than a certain threshold values, the 3rd H bridge switch pipe Q3 conducting and the
It is low level that one H bridge switch pipe Q1, which turns off the first tie point (i.e. A point), this low-voltage acts on the grid of the 2nd H bridge switch pipe Q2
The grid of pole and the 4th H bridge switch pipe Q4 makes the 2nd H bridge switch pipe Q2 conducting and the 4th H bridge switch pipe Q4 shutdown, the second connection
Point (i.e. B point) is high level, namely establishes that the first tie point (i.e. A point) is low level, the second tie point (i.e. B point) is at this time
The circuit state of high level；At this moment the first tie point (i.e. A point) is low level and the second tie point (i.e. B point) is the electricity of high level
Pressure can be added on magnetic field detection coil LS (or on magnetic field detection coil LS and magnetic field detection coil current sampling resistor R2), due to
Magnetic field detection coil LS is an inductance element, and electric current cannot be mutated, therefore the second tie point (i.e. B point) and the first tie point (i.e. A
Point) on voltage the electric current opposite direction on magnetic field detection coil LS can be made constantly to increase (defined at this time from the second tie point (i.e. B
Point) to the first tie point (i.e. A point) electric current be negative current), this electric current can flow through current-limiting resistance R1, make on current-limiting resistance R1
Voltage is also continuously increased, and is also constantly increased so as to cause the first tie point (i.e. A point) voltage；
Step 7: when the electric current on magnetic field detection coil LS is greater than a certain threshold values, magnetic field detection coil LS inductance saturation,
Its electric current rises rapidly, and voltage and the first tie point (i.e. A point) voltage on current-limiting resistance R1 also and then rises rapidly；
Step 8: when the first tie point (i.e. A point) voltage is greater than a certain threshold values, the 4th H bridge switch pipe Q4 conducting and the
Two H bridge switch pipe Q2 shutdown, the second tie point (i.e. B point) are low level, this low-voltage acts on the grid of the first H bridge switch pipe Q1
The grid of pole and the 3rd H bridge switch pipe Q3 makes the first H bridge switch pipe Q1 conducting and the 3rd H bridge switch pipe Q3 shutdown, the first connection
Point (i.e. A point) is high level, namely establishing the first tie point (i.e. A point) at this time is high level, and the second tie point (i.e. B point) is
Low level circuit state.
The present invention by so constantly vibrating repeatedly, the inductance of frequency of oscillation and supply voltage, magnetic field detection coil LS
The relating to parameters of amount, current-limiting resistance R1, magnetic field detection coil current sampling resistor R2.
Circle number magnetic field detection coil LS appropriate by the suitable magnetic material of selection and coiling, while designing suitable current limliting electricity
The parameter for hindering R1 and magnetic field detection coil current sampling resistor R2, makes magnetic field detection coil LS work in positive counter magnetic field saturation state
(referred to as fluxgate), the positive antisymmetry of fluxgate under normal circumstances, under no external magnetic fields, magnetic field detection coil LS two
The operating voltage at end or its operating current average value be zero namely magnetic field detection coil current sampling resistor R2 on voltage be averaged
Value is zero.
Due to fluxgate of the invention be single supply work (circuit diagram of the present invention is operable with dual power supply or single supply, but
Its oscillating circuit is single supply work), symmetry is not influenced by power supply, and (it is preferably right to have than the fluxgate that dual power supply works
Title property), to guarantee that circuit has high sensitivity and detection accuracy.
When there is external magnetic fields (magnetic field that current sensor is usually primary current), the positive skew-symmetry of fluxgate
It can be broken, at this time its operating voltage (the first tie point (i.e. A point) subtracts the voltage on the second tie point (i.e. B point)) average value
Or current average be not zero namely magnetic field detection coil current sampling resistor R2 on average voltage be not zero, this voltage
After the amplification of subsequent differential filtering amplifying circuit, directly export.
The present invention is based on magnetic field detection coil voltages or current average to detect, and by making the difference to this voltage or electric current
Divide filter shape amplification, final output one detects signal, and the voltage or the voltage on current sampling resistor R2 of magnetic field detection coil LS is
The input quantity of differential filtering amplifying circuit, circuit of the present invention is simple and practical, and performance is good, at low cost, and consistency is good.
The present invention has split a kind of open loop magnetic flux gate control circuit different from integrating fluxgate control chip, present invention electricity
Road is simple and practical, and price is low, and performance is high, because fluxgate is that open loop works, therefore can be influenced by fluxgate is magnetically saturated, can usually be surveyed
Milliampere grade is measured to the electric current of several hundred peace grades, in certain current range, output is directly proportional to output electric current.
It should be noted that above-described embodiment can be freely combined as needed.The above is only of the invention preferred
Embodiment, but the present invention is not limited to the specific details in the above embodiment, it is noted that for the art
For those of ordinary skill, within the scope of the technical concept of the present invention, without departing from the principle of the present invention, it can also do
Several improvements and modifications out carry out a variety of equivalents to technical solution of the present invention, these improvement, retouching and equivalents
It should be regarded as protection scope of the present invention.
Claims (7)
1. a kind of self-excitation type open loop fluxgate current sensor circuit, characterized in that it comprises:
Positive supply；
Negative supply or the reference zero of setting；
Self-maintained circuit, including the first H bridge switch pipe, the 2nd H bridge switch pipe, the 3rd H bridge switch pipe, the 4th H bridge switch pipe,
Magnetic field detection coil and current-limiting resistance；Wherein the source electrode of the source electrode of the first H bridge switch pipe and the 2nd H bridge switch pipe connects simultaneously
It is connect with positive supply；The source electrode of 3rd H bridge switch pipe and the source electrode of the 4th H bridge switch pipe connect and pass through leakage resistance of rationing the power supply
It is connected to the reference zero of negative supply or setting；The drain electrode of first H bridge switch pipe connects and connects with the drain electrode of the 3rd H bridge switch pipe
Contact is the first tie point；The drain electrode of 2nd H bridge switch pipe is connected with the drain electrode of the 4th H bridge switch pipe and tie point is the second company
Contact；Magnetic field detection coil is connected between the first tie point and the second tie point；The grid and the 3rd H of first H bridge switch pipe
The grid of bridge switch pipe links together and is connected to the second tie point；The grid and the 4th H bridge switch pipe of 2nd H bridge switch pipe
Grid link together and be connected to the first tie point；And
Differential filtering amplifying circuit is connect with first tie point or the magnetic field detection coil, the differential filtering amplification
The output end of circuit is the voltage output end of the self-excitation type open loop fluxgate current sensor circuit.
2. self-excitation type open loop fluxgate current sensor circuit according to claim 1, it is characterised in that: the difference filter
Wave amplifying circuit include operational amplifier, the first differential resistor, the second differential resistor, third differential resistor, the 4th differential resistor,
First integral capacitor and second integral capacitor；Wherein first differential resistor is connected to the first tie point and operational amplifier
Between reverse input end, the second differential resistor and the 4th differential resistor are connected in series and are connected to the second tie point and operation amplifier
Between the positive input of device, third differential resistor and first integral capacitor are connected in parallel and are connected to the reversed of operational amplifier
Between input terminal and the output end of operational amplifier, second integral capacitor one end is connected to the positive input of operational amplifier,
The second integral capacitor other end connects the reference zero of negative supply or setting.
3. self-excitation type open loop fluxgate current sensor circuit according to claim 1, it is characterised in that: described from exciting
Swinging circuit further includes the magnetic field detection coil current sampling resistor being connected in series with magnetic field detection coil, magnetic field detection coil and magnetic
Field detecting coil current sampling resistor is connected in series between the first tie point and the second tie point.
4. self-excitation type open loop fluxgate current sensor circuit according to claim 3, it is characterised in that: the difference filter
Wave amplifying circuit include operational amplifier, the first differential resistor, the second differential resistor, third differential resistor, the 4th differential resistor,
First integral capacitor and second integral capacitor；Wherein first differential resistor one end is connected to magnetic field detection coil and magnetic field inspection
Between test coil current sampling resistor, the reverse input end of the first differential resistor other end and operational amplifier is connected, and second is poor
Sub-resistance and the 4th differential resistor are connected in series and are connected between the second tie point and the positive input of operational amplifier, the
Three differential resistors and first integral capacitor are connected in parallel and are connected to the reverse input end and operational amplifier of operational amplifier
Between output end, second integral capacitor one end is connected to the positive input of operational amplifier, and the second integral capacitor other end connects
Connect the reference zero of negative supply or setting.
5. self-excitation type open loop fluxgate current sensor circuit according to claim 1 to 4, it is characterised in that: described
First H bridge switch pipe and the 2nd H bridge switch pipe are p-type metal-oxide-semiconductor, and the 3rd H bridge switch pipe and the 4th H bridge switch pipe are N-type MOS
Pipe.
6. according to the self-oscillation method of any self-excitation type open loop fluxgate current sensor circuit of claim 2 or 5,
It is characterized in that, includes the following steps:
Step 1: when being powered, it is assumed that the first H bridge switch pipe is first open-minded, and when the first H bridge switch pipe is opened, the first tie point is
High level；
Step 2: the high level of the first tie point is added on the grid of the 2nd H bridge switch pipe and the grid of the 4th H bridge switch pipe,
Keep the shutdown of the 2nd H bridge switch pipe and the 4th H bridge switch pipe open-minded, makes the second tie point low level；
Step 3: the low level of the second tie point acts on the grid of the first H bridge switch pipe and the grid of the 3rd H bridge switch pipe,
It opens the first H bridge switch pipe to turn off with the 3rd H bridge switch pipe, namely establishing the first tie point at this time is high level, second
Tie point is low level circuit state；
Step 4: the first tie point established is high level and the second tie point is that low level voltage can be added to magnetic field detection line
On circle, the voltage on the first tie point and the second tie point can be such that the electric current on magnetic field detection coil constantly increases, and define at this time
It is positive current from the first tie point to the electric current of the second tie point, this electric current can flow through current-limiting resistance, make the electricity on current-limiting resistance
Pressure is also continuously increased, and the voltage on the second tie point is caused also constantly to increase；
Step 5: magnetic field detection coil inductance is saturated when the electric current on magnetic field detection coil is greater than a certain threshold values, electric current is fast
Speed rises, and the voltage and the second tie point voltage on current-limiting resistance also and then rise rapidly；
Step 6: the conducting of the 3rd H bridge switch pipe and the first H bridge switch pipe close when the second tie point voltage is greater than a certain threshold values
Disconnected first tie point is low level, this low-voltage acts on the grid of the 2nd H bridge switch pipe and the grid of the 4th H bridge switch pipe,
Make the conducting of the 2nd H bridge switch pipe and the shutdown of the 4th H bridge switch pipe, the second tie point is high level, namely establishes first at this time
Tie point is low level, the circuit state that the second tie point is high level；At this moment the first tie point is low level and the second connection
Point is that the voltage of high level can be added on magnetic field detection coil, and the voltage on the second tie point and the first tie point can be such that magnetic field examines
Electric current opposite direction on test coil constantly increases, and being defined at this time from the second tie point to the electric current of the first tie point is negative current,
This electric current can flow through current-limiting resistance, be continuously increased the voltage on current-limiting resistance also, not lead to voltage on the first tie point also not
It is disconnected to increase；
Step 7: magnetic field detection coil inductance is saturated when the electric current on magnetic field detection coil is greater than a certain threshold values, electric current is fast
Speed rises, and the voltage and the first tie point voltage on current-limiting resistance also and then rise rapidly；
Step 8: the conducting of the 4th H bridge switch pipe and the 2nd H bridge switch pipe close when the first tie point voltage is greater than a certain threshold values
Disconnected, the second tie point is low level, this low-voltage acts on the grid of the first H bridge switch pipe and the grid of the 3rd H bridge switch pipe,
Make the conducting of the first H bridge switch pipe and the shutdown of the 3rd H bridge switch pipe, the first tie point is high level, namely establishes first at this time
Tie point is high level, and the second tie point is low level circuit state.
7. according to the self-oscillation method of any self-excitation type open loop fluxgate current sensor circuit of claim 3 to 5,
It is characterized in that, includes the following steps:
Step 1: when being powered, it is assumed that the first H bridge switch pipe is first open-minded, and when the first H bridge switch pipe is opened, the first tie point is
High level；
Step 2: the high level of the first tie point is added on the grid of the 2nd H bridge switch pipe and the grid of the 4th H bridge switch pipe,
Keep the shutdown of the 2nd H bridge switch pipe and the 4th H bridge switch pipe open-minded, makes the second tie point low level；
Step 3: the low level of the second tie point acts on the grid of the first H bridge switch pipe and the grid of the 3rd H bridge switch pipe,
It opens the first H bridge switch pipe to turn off with the 3rd H bridge switch pipe, namely establishing the first tie point at this time is high level, second
Tie point is low level circuit state；
Step 4: the first tie point established is high level and the second tie point is that low level voltage can be added to magnetic field detection line
On circle and magnetic field detection coil current sampling resistor, the voltage on the first tie point and the second tie point can make magnetic field detection coil
On electric current constantly increase, being defined at this time from the first tie point to the electric current of the second tie point is positive current, this electric current can flow through
Current-limiting resistance is continuously increased the voltage on current-limiting resistance also, and the voltage on the second tie point is caused also constantly to increase；
Step 5: magnetic field detection coil inductance is saturated when the electric current on magnetic field detection coil is greater than a certain threshold values, electric current is fast
Speed rises, and the voltage and the second tie point voltage on current-limiting resistance also and then rise rapidly；
Step 6: the conducting of the 3rd H bridge switch pipe and the first H bridge switch pipe close when the second tie point voltage is greater than a certain threshold values
Disconnected first tie point is low level, this low-voltage acts on the grid of the 2nd H bridge switch pipe and the grid of the 4th H bridge switch pipe,
Make the conducting of the 2nd H bridge switch pipe and the shutdown of the 4th H bridge switch pipe, the second tie point is high level, namely establishes first at this time
Tie point is low level, the circuit state that the second tie point is high level；At this moment the first tie point is low level and the second connection
Point is that the voltage of high level can be added on magnetic field detection coil and magnetic field detection coil current sampling resistor, the second tie point and the
Voltage on one tie point can be such that the electric current opposite direction on magnetic field detection coil constantly increases, define at this time from the second tie point to
The electric current of first tie point is negative current, this electric current can flow through current-limiting resistance, be continuously increased the voltage on current-limiting resistance also, lead
The voltage on the first tie point is caused also constantly to increase；
Step 7: magnetic field detection coil inductance is saturated when the electric current on magnetic field detection coil is greater than a certain threshold values, electric current is fast
Speed rises, and the voltage and the first tie point voltage on current-limiting resistance also and then rise rapidly；
Step 8: the conducting of the 4th H bridge switch pipe and the 2nd H bridge switch pipe close when the first tie point voltage is greater than a certain threshold values
Disconnected, the second tie point is low level, this low-voltage acts on the grid of the first H bridge switch pipe and the grid of the 3rd H bridge switch pipe,
Make the conducting of the first H bridge switch pipe and the shutdown of the 3rd H bridge switch pipe, the first tie point is high level, namely establishes first at this time
Tie point is high level, and the second tie point is low level circuit state.
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