A kind of improve magnetic flux transducer dynamic output range from zero amplifying circuit
Technical field
The present invention relates to belong to field of civil engineering, be applied to structural safety health monitoring industry, be specifically related to one and carry
High magnetic flux sensor dynamic output range from zero amplifying circuit.
Background technology
At present, the detection of domestic bridge cable force is typically with following several method: oil gauge method, pressure transducer are surveyed
Fixed, vibratory drilling method (frequency method) etc..But, owing to oil gauge method exists the easy off normal of pointer, during high pressure, pointer shake is big, and reading is artificial
The shortcomings such as error is big;Determination of pressure sensor method dynamic response is poor, the problems such as the life-span is short, expensive;Vibratory drilling method (frequency method)
Reliability depend on the installation site of vibration pickup, it is impossible to realize the problems such as round-the-clock detection;But, in recent years for bridge cable
Power detection occurs in that with the mensuration new method as representative of magnetic flux, and has higher future in engineering applications.Bridge cable force magnetic flux
The principle of quantity measuring method is magnetoelastic effect based on ferrimagnet, i.e. when the external mechanical load that ferrimagnet bears
When changing, its internal intensity of magnetization (pcrmeability) changes.In engineering practice, by test ferrimagnet system
The pcrmeability change of the component become i.e. can be used to measure the internal stress of component.But current magnetic flux data collecting system
In, the full scale induced signal of sensor output is typically tens to hundreds of millivolt, and extraneous electromagnetic interference, the background of equipment are made an uproar
Sound all can produce impact to the output signal of sensor, thus reduces the certainty of measurement of system.Again because magnetic flux transducer exists
During cable zero stress, can export the induced voltage under current state, the induced voltage of other range is relative to cable zero and is subject to
Relative change during power, induced voltage can obtain the integral voltage of corresponding real physical, now again through integrating circuit
Integral voltage (zero point base value) the most dynamic range of the analog-digital converter that accounted for, if so not eliminating cable zero
Zero state inductive voltage value during stress, then either the dynamic range of analog-digital converter is wasted or the amplification of rear class signal
All it is limited.
Summary of the invention
In place of the present invention is to solve the deficiencies in the prior art, a kind of new amplifying circuit of special release, concrete scheme is:
A kind of improve magnetic flux transducer dynamic output range from zero amplifying circuit, including magnetic flux transducer, integrating circuit, simulation
Switch, subtraction circuit, amplifier, low pass filter, analog-digital converter, microcontroller, digital to analog converter;It is characterized in that: institute
The induced signal stating magnetic flux transducer output exports integral voltage by integrating circuit, and arrives subtraction electricity through analog switch
Rood is to the sensor signal of zero suppression, then it is micro-to be converted into digital quantity by amplifier and low pass filter through analog-digital converter
Controller reads.
Preferably, the zero point base value that integrating circuit exports is directly inputted to modulus by microprocessor controls analog switch and turns
Change.
Preferably, zero point base value is input to subtraction circuit by digital to analog converter by microcontroller.
Preferably, integral voltage improves signal to noise ratio through amplifier after subtraction circuit deducts zero point base value again.
Preferably, microprocessor controls analog switch selects signal link.
The induced voltage signal that operation principle, first magnetic flux transducer inner cable export in zero stress is electric by integration
Road is converted into the variable quantity of cable magnetic flux, because integrating circuit has a time constant, so after integrating circuit, output
Signal or magnitude of voltage, this value is denoted as U0.Need for the first time because of system to obtain zero point base value voltage U0, therefore next stage passes through
One analog switch being controlled by microcontroller, directly nurses one's health signal in analog-digital converter, and by this value record at micro-control
In device processed.When system enters measuring phases, such as cable have received external force.And the signal produced obtains after integrating circuit
Arrive as U1, now signal chains is switched to subtractor one tunnel by analog switch by microcontroller, and microcontroller passes through digital-to-analogue simultaneously
The U that transducer will be kept0It is configured to the input of subtractor, prepares and U1Carry out subtraction.So work as U1Arrive subtractor
After, with U0Subtract each other, obtain a relative and U0Variation delta U, this variable quantity be exactly the cable that arrives of magnetic flux transducer measurement from
0 stress is to during by some force value, and the change in electric amount reflected, this signal, because amplitude is little, can pass through next
Level is amplified the sensitivity enhancement of sensor, then through analog-digital converter after low-pass filtered device general's interference target signal filter, thus
The out-put dynamic range making sensor increases, and improves the certainty of measurement of system.
This circuit utilizes amplifying circuit can amplify signal, and the principle that equipment background noise is amplified the most equally, improve
The signal to noise ratio of system, thus improve the certainty of measurement of system.As when circuit not zero suppression, signal is already close to analog-digital converter
Half range, if now by signal amplifier, signal will clipping distortion, if do not amplified, such as signal voltage value is
2.5V, the interference that equipment background noise brings is ± 1mV, and system full scale variable quantity is 100mV, then owing to equipment background is made an uproar
The error that vocal cords come is up to ± 1%;And by after zero suppression amplifying circuit, such as by the zero point base value zero setting of 2.5V, now
By amplifying circuit, signal can be amplified 5~10 times, when such as amplifying 5 times, now equipment background noise is basically unchanged, and signal is full
Range variable quantity is 500mV, then the error of system will be reduced to ± 0.2%.
The present invention is made zero by the zero point base value measured to by magnetic flux transducer on circuit, and through amplifying circuit pair
Dynamic Signal amplifies, thus directly enhances the sensitivity of sensor, improves the capacity of resisting disturbance of system, so that system is surveyed
Accuracy of measurement is greatly promoted.
Accompanying drawing explanation
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
In having technology to describe, the required accompanying drawing used is briefly described, it should be apparent that, the accompanying drawing in describing below is only this
Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, it is also possible to
Other accompanying drawing is obtained according to these accompanying drawings.
Fig. 1 is the theory diagram of the present invention.
Fig. 2 is that the present invention is from zero suppression analog module part.
Fig. 3 is filtering and amplifying circuit part of the present invention.
Description of reference numerals:
1, magnetic flux transducer;2, integrating circuit;3, analog switch;4, subtraction circuit;5, amplifier;6, low-pass filtering
Device;7, analog-digital converter;8, microcontroller;9, digital to analog converter.
Detailed description of the invention
Theory diagram as shown in Figure 1, a kind of improve magnetic flux transducer dynamic output range from zero suppression amplifying circuit,
It includes that magnetic flux transducer 1, integrating circuit 2, analog switch 3, subtraction circuit 4, amplifier 5, low pass filter 6, modulus turn
Parallel operation 7, microcontroller 8, digital to analog converter 9;It is characterized in that: the induced signal of magnetic flux transducer 1 output is by integration electricity
Road 2 exports integral voltage, and arrives subtraction circuit 4 through analog switch 3 and obtain the sensor signal of zero suppression, then passes through amplifier
5 and low pass filter 6 be converted into digital quantity through analog-digital converter 7 and read by microcontroller 8;The zero point of integrating circuit 2 output
Base value controls analog switch 7 by microcontroller 8 and is directly inputted to analog digital conversion 9;Zero point base value is passed through digital-to-analogue by microcontroller 8
Transducer 9 is input to subtraction circuit 4;Integral voltage improves letter through amplifier 5 after subtraction circuit 4 deducts zero point base value again
Make an uproar ratio;Microcontroller 8 controls analog switch 3 to select signal link.
First the induced voltage signal that magnetic flux transducer inner cable exports in zero stress is converted into by integrating circuit
The variable quantity of cable magnetic flux, because integrating circuit has a time constant, so after integrating circuit, the signal of output is also
It is magnitude of voltage, this value is denoted as U0.Need for the first time because of system to obtain zero point base value voltage U0, therefore next stage is controlled by one
In the analog switch of microcontroller, signal is directly nursed one's health in analog-digital converter, and by this value record in the microcontroller.When
When system enters measuring phases, such as cable have received external force.And the signal produced obtains as U after integrating circuit1, this
Time microcontroller by analog switch, signal chains switched to subtractor one tunnel, microcontroller will be protected by digital to analog converter simultaneously
The U kept0It is configured to the input of subtractor, prepares and U1Carry out subtraction.So work as U1After arriving subtractor, with U0Phase
Subtract, obtain a relative and U0Variation delta U, this variable quantity be exactly the cable that arrives of magnetic flux transducer measurement from 0 stress to
During by some force value, the change in electric amount reflected, this signal is because amplitude is little, and can be amplified by next stage will
Through analog-digital converter after the sensitivity enhancement of sensor, more low-pass filtered device general's interference target signal filter, so that sensing
The out-put dynamic range of device increases, and improves the certainty of measurement of system.
In the present embodiment, the integrating amplification circuit of signal chains part, subtractor, amplifier, wave filter etc. use low noise
Sound pitch precision amplifier, in reality, integrating circuit uses OP297, and other parts use OPA2277.Digital to analog converter part uses
AD420 is through the combination of outside amplifier so that and digital to analog converter output can reach ± output area of 10V.AD420 is by number
Word interface is connected to microcontroller, microcontroller configure its output voltage, inputs for subtractor wherein one end.Zero point integration
After the voltage of voltage and digital to analog converter AD420 configuration subtracts each other, output to in-phase proportion amplifying circuit U71B, then through low pass filtered
Ripple device U66A enters analog-digital converter.When system obtains zero point base value for the first time, analog switch is passed through in integrating circuit output
The choosing of ADG1219 direct sheet is read out to analog-digital converter.
The effect of the present invention is: this circuit utilizes amplifying circuit can amplify signal, and the most same to equipment background noise
The principle amplified, improves the signal to noise ratio of system, thus improves the certainty of measurement of system.As when circuit not zero suppression, signal is
Through close to half range of analog-digital converter, if now by signal amplifier, signal will clipping distortion, if do not amplified,
Such as signal voltage value is 2.5V, and the interference that equipment background noise brings is ± 1mV, and system full scale variable quantity is 100mV, that
The error brought due to equipment background noise is up to ± 1%;And by after zero suppression amplifying circuit, such as by the zero of 2.5V
Point base value zero setting, now can amplify 5~10 times by amplifying circuit by signal, when such as amplifying 5 times, and now equipment background noise
Being basically unchanged, signal full scale variable quantity is 500mV, then the error of system will be reduced to ± 0.2%.
The above, the only detailed description of the invention of the present invention, but protection scope of the present invention is not limited thereto, and any
The change expected without creative work or replacement, all should contain within protection scope of the present invention.Therefore, the present invention
Protection domain should be as the criterion with the protection domain that claims are limited.