CN104897042B - The measurement of mutual inductance system and method for magnetic suspension mechanism gas length - Google Patents
The measurement of mutual inductance system and method for magnetic suspension mechanism gas length Download PDFInfo
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- CN104897042B CN104897042B CN201510221266.3A CN201510221266A CN104897042B CN 104897042 B CN104897042 B CN 104897042B CN 201510221266 A CN201510221266 A CN 201510221266A CN 104897042 B CN104897042 B CN 104897042B
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Abstract
The invention discloses a kind of measurement of mutual inductance system and methods of magnetic suspension mechanism gas length, the measuring system is by suspension mechanism, power of electromagnet driving unit, two locking phase amplifying units and digital signal processing unit are constituted, one locking phase amplifying unit is used for sensed current signal amplitude, another locking phase amplifying unit is used for the amplitude of detectable voltage signals, the suspension mechanism is made of electromagnet and suspended substance, the power of electromagnet driving unit includes H bridge type circuit and Hall current sensor, the locking phase amplifying unit, including pre-filtering amplifier, phase sensitive detector and low-pass filter, the digital signal processing unit uses CPU processor.The present invention, only need to be in electromagnet coil processing in the case of non-use position sensor, and pre-buried mutual inductor passes through the measurement to pre-buried coil mutual voltage and electromagnet coil current, so that it may to calculate the gas length of magnetic suspension mechanism.
Description
Technical field
The present invention relates to the control fields of position-sensor-free magnetic suspension system, and in particular to a kind of magnetic suspension mechanism air gap
The measurement of mutual inductance system and method for length.
Background technology
PWM active control type magnetic levitation technologies are adjusted using closed-loop control means using the electromagnet apparatus of PWM drivings
Magnetic field force makes to keep certain gap between suspended substance and electromagnet, realizes the purpose of suspension.Magnetic suspension can effectively avoid object
Friction is contacted between body, therefore is had broad application prospects.Magnetic levitation technology has obtained widely answering in many fields
With, such as magnetic suspension train, magnetic suspension bearing, high speed magnetic suspension motor.
Current most of active control type magnetic suspension mechanisms measure gas length using position sensor.Sensor substantially divides
For two classes, laser range sensor, eddy current displacement sensor.Due to the presence of position sensor, the cost of system is increased
With the difficulty of assembly, it is unfavorable for the miniaturization of magnetic suspension mechanism and cost effective.
Invention content
To solve the above problems, the present invention provides a kind of measurement of mutual inductance system of magnetic suspension mechanism gas length and sides
Method only need to be in electromagnet coil processing in the case of non-use position sensor, pre-buried mutual inductor, by pre-buried
The measurement of coil mutual inductance voltage and electromagnet coil current, so that it may to calculate the gas length of magnetic suspension mechanism.
To achieve the above object, the technical solution that the present invention takes is：
The measurement of mutual inductance system of magnetic suspension mechanism gas length, the measuring system are driven by suspension mechanism, power of electromagnet
Moving cell, two locking phase amplification (LIA) units and digital signal processing unit are constituted, and a locking phase amplifying unit is for detecting electricity
Signal amplitude is flowed, another locking phase amplifying unit is used for the amplitude of detectable voltage signals, and the suspension mechanism is by electromagnet and hangs
Floating body is constituted, and the power of electromagnet driving unit includes H bridge type circuit and Hall current sensor, and the locking phase amplification is single
Member, including pre-filtering amplifier, phase sensitive detector (PSD) and low-pass filter (LPF), the digital signal processing unit are adopted
With CPU processor, the digital signal processing unit is connected by both threads cable with suspension mechanism, and single line cable is for driving electricity
Magnet, another cable is for measuring mutual voltage.
Wherein, two described locking phase amplification (LIA) units are all made of AD630 chips；The output of Hall current sensor passes through
Cross signal condition, after filter and amplification, it is Sig_Input signals to be input in 1 foot of phase demodulation chip AD630, while CPU will
It with PWM wave with frequency, and by the square wave of phase shift processing, is input in 9 feet of AD630, the reference signal as locking phase amplification；
Sig_Input signals are phase locked amplification in AD630, and the output signal of AD630 obtains fundamental frequency containing electric current after low-pass filtering
The signal Output of the amplitude information of component；This signal is input to after signal condition in digital signal processing unit.
To solve the above problems, the present invention also provides a kind of measurement of mutual inductance method of magnetic suspension mechanism gas length, packet
Include following steps：
S1, CPU send out PWM drive signal to power of electromagnet driving unit, and electromagnet coil generates electric current, and suspended substance exists
The lower movement of electromagnetic force control makes air gap x change, and then changes the magnetic resistance and coil current of magnetic circuit；
S2, amplify (LIA) technology using locking phase, the change in location information extraction that will drown out in current harmonics signal goes out
Come；
S3, according to the relationship of the amplitude and electric current of fundamental frequency driving voltage component in pwm signal, calculated in CUP processor
Go out gas length.
Wherein, the movement makes the calculation formula of air gap x be：
In formula, N is the number of turns of electromagnet coil, μ0Indicate that space permeability, A indicate the sectional area of electromagnet core, ω0
Indicate that pulse-width signal fundamental wave angular frequency, m are the number of turns of pre-buried mutual inductor, Ui0Indicate current first harmonics signal amplitude, Uue0Table
Show that the amplitude of fundamental frequency driving voltage component, I indicate the length of iron core in magnetic circuit, μrIndicate iron core relative permeability.
The invention has the advantages that：
Using phase lock amplifying technology, magnetic suspension mechanism measurement of air gap problem is handled；It is led back using using mutual inductor measurement
On the one hand on the other hand road fundamental frequency voltages can eliminate shadows of the resistance drop iR to measurement to avoid major loop DC influence
It rings, improves the precision of measurement；Influence of the control signal dutyfactor to measurement of air gap is considered, with other position-sensor-free sides
Method is compared, and is measured more accurate；Electromagnet is used as executing agency, and the Sensitive Apparatus measured as magnetic resistance；With existing utilization
Laser position sensors and the scheme of electric eddy current measurement are compared, and this method cost is lower, it is easier to and it is integrated, it is more suitable for installing
And debugging.
Description of the drawings
A kind of system construction drawing of the measurement of mutual inductance system of magnetic suspension mechanism gas length of Fig. 1 embodiment of the present invention
Fig. 2 is the simplification figure of Fig. 1.
Fig. 3 is the equivalent magnetic circuit modeling schematic diagram of magnetic levitation system in the embodiment of the present invention.
Fig. 4 is the equivalent equivalent circuit diagram of magnetic levitation system in the embodiment of the present invention.
Fig. 5 is AD630 locking phase amplifying circuits in the embodiment of the present invention.
Specific implementation mode
In order to make objects and advantages of the present invention be more clearly understood, the present invention is carried out with reference to embodiments further
It is described in detail.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not used to limit this hair
It is bright.
As shown in Figs. 1-2, an embodiment of the present invention provides a kind of measurement of mutual inductance system of magnetic suspension mechanism gas length, institutes
Measuring system is stated by suspension mechanism, power of electromagnet driving unit, two locking phase amplification (LIA) units and Digital Signal Processing list
Member is constituted, and a locking phase amplifying unit is used for sensed current signal amplitude, another locking phase amplifying unit is for detecting voltage letter
Number amplitude, the suspension mechanism is made of electromagnet and suspended substance, and the power of electromagnet driving unit includes H bridge type circuit
And Hall current sensor, the locking phase amplifying unit, including pre-filtering amplifier, phase sensitive detector (PSD) and low pass filtered
Wave device (LPF), the digital signal processing unit use CPU processor, the digital signal processing unit to pass through both threads cable
It is connected with suspension mechanism, single line cable is used for drive electromagnet, and another cable is for measuring mutual voltage.
As shown in figure 5, two described locking phase amplification (LIA) units are all made of AD630 chips；Hall current sensor it is defeated
Go out by signal condition, after filter and amplification, it is Sig_Input signals to be input in 1 foot of phase demodulation chip AD630, simultaneously
CPU will be input to PWM wave with frequency, and by the square wave of phase shift processing in 9 feet of AD630, the reference letter as locking phase amplification
Number；Sig_Input signals are phase locked amplification in AD630, and the output signal of AD630 obtains containing electric current after low-pass filtering
The signal Output of the amplitude information of fundamental component；This signal is input to after signal condition in digital signal processing unit.
The embodiment of the present invention additionally provides a kind of measurement of mutual inductance method of magnetic suspension mechanism gas length, including walks as follows
Suddenly：
S1, CPU send out PWM drive signal to power of electromagnet driving unit, and electromagnet coil generates electric current, and suspended substance exists
The lower movement of electromagnetic force control makes air gap x change, and then changes the magnetic resistance and coil current of magnetic circuit；
S2, amplify (LIA) technology using locking phase, the change in location information extraction that will drown out in current harmonics signal goes out
Come；
S3, according to the relationship of the amplitude and electric current of fundamental frequency driving voltage component in pwm signal, calculated in CUP processor
Go out gas length.
Wherein, the movement makes the calculation formula of air gap x be：
In formula, N is the number of turns of electromagnet coil, μ0Indicate that space permeability, A indicate the sectional area of electromagnet core, ω0
Indicate that pulse-width signal fundamental wave angular frequency, m are the number of turns of pre-buried mutual inductor, Ui0Indicate current first harmonics signal amplitude, Uue0Table
Show that the amplitude of fundamental frequency driving voltage component, I indicate the length of iron core in magnetic circuit, μrIndicate iron core relative permeability.
Described move makes the calculation formula of air gap x be obtained by following steps：
As shown in Figure 3-4, it is main coil turn to take N, and i is coil current, and m is the number of turns of mutual inductor, mutual inductor with
Differential amplifier circuit is connected, it can be considered that mutual inductor is opened a way, voltage Ue.Ni is the magnetomotive force of system, RmFor system
Magnetic resistance.The magnetic resistance of system is represented by if ignoring leakage field and effect of end surface：
Wherein, I indicates core length in magnetic circuit (containing suspended substance), and x indicates gas length, μ0For space permeability, μrFor iron
The relative permeability of core material, A indicate the area of iron core
According to the relationship of magnetic resistance and inductance, have：
The magnetic linkage of electromagnet is：
ψ=Li (3)
If electromagnet both ends making alive u, electromagnet coil resistance is R, then can list electromagnet current loop equation is：
Wherein, e is induced voltage.The voltage in mutual inductance circuit is：
If ignoring the back-emf item of electromagnet, that is,Then have
By L and RmRelationship (2) bring (6) formula into, have
Fourier analysis is carried out to (7) formula, fundamental frequency situation is only considered, has：
Wherein, iv0For the fundamental component of electric current, uev0For the fundamental component of mutual inductor voltage.
It enables：Ui0For the amplitude of the fundamental component signal of i, Uue0For ueFundamental component signal amplitude, according to (8) formula, two
The relationship of person is as follows：
If Ui0And Uue0It is known that then gas length can be expressed as：
This specific implementation measures the amplitude U of electric current fundamental component using phase lock amplifying technologyi0And Uue0.Amplified using phase sensitivity
It is as follows that technology extracts the reason of signal amplitude information：
A) it utilizes phase sensitive detector to realize the demodulating process of modulated signal, can be examined simultaneously using frequency and phase
It surveys, interference noise is again very low with the probability of phase with frequency with signal；
B) for comparing conventional demodulator, lock-in amplifier uses low-pass filtering, passband that can be made very narrow, and
Its bandwidth by modulation frequency influence, does not have good stability.
C) electromagnet is encouraged by pwm pulse signal and generates electromagnetic force, and PWM fundamental frequency signals are carrier signal, location information
It is modulated in PWM fundamental frequency signals, therefore can be directly using the fundamental component in pwm signal as with reference to signal.
During the realization of this specific implementation, the processor used in CPU can be microcontroller, DSP, ARM, FPGA,
PC104, PC machine etc.；Reference signal can be sent out by CPU processor, can also be used special phaselocked loop (PLL) circuit, be generated and use
In the reference signal of locking phase amplification；The locking phase amplifying circuit that ADb30 is core may be used in locking phase amplifying unit, can also use
The locking phase amplifying circuit built by high-speed analog switch circuit, or directly realize that locking phase amplifies work(by way of digital servo-control amplification
Energy；The function of Hall current sensor can be replaced with sampling resistor, i.e., in one copper-manganese Low Drift Temperature sampling electricity of H bridges lower end series connection
Resistance, then resistive voltage is measured with differential amplifier circuit, and then electric current is obtained by way of calculating.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, without departing from the principle of the present invention, it can also make several improvements and retouch, these improvements and modifications are also answered
It is considered as protection scope of the present invention.
Claims (4)
1. the measurement of mutual inductance system of magnetic suspension mechanism gas length, which is characterized in that the measuring system is by suspension mechanism, electromagnetism
Iron power drive unit, two locking phase amplifying units and digital signal processing unit are constituted, and a locking phase amplifying unit is for examining
Current signal amplitude is surveyed, another locking phase amplifying unit is used for the amplitude of detectable voltage signals, and the suspension mechanism is by electromagnet
It is constituted with suspended substance, the power of electromagnet driving unit includes H bridge type circuit and Hall current sensor, the locking phase amplification
Unit, including pre-filtering amplifier, phase sensitive detector and low-pass filter, the digital signal processing unit is using at CPU
Device is managed, the digital signal processing unit is connected by both threads cable with suspension mechanism, and single line cable is used for drive electromagnet, separately
Single line cable is for measuring mutual voltage；Wherein, pumping signal controls signal using power of electromagnet driving unit, and form is
Pwm pulse.
2. the measurement of mutual inductance system of magnetic suspension mechanism gas length according to claim 1, which is characterized in that described in two
Locking phase amplifying unit is all made of AD630 chips；Signal condition is passed through in the output of Hall current sensor, after filter and amplification, input
To in 1 foot of phase demodulation chip AD630 be Sig_Input signals, while CPU will with PWM wave with frequency, and by phase shift handle
Square wave, be input in 9 feet of AD630, as locking phase amplification reference signal；Sig_Input signals are phase locked in AD630
Amplification, the output signal of AD630 obtain the signal Output of the amplitude information of the fundamental component containing electric current after low-pass filtering；
This signal is input to after signal condition in digital signal processing unit.
3. a kind of magnetic suspension mechanism air gap of measurement of mutual inductance system using magnetic suspension mechanism gas length described in claim 1
The measurement of mutual inductance method of length, which is characterized in that include the following steps：
S1, CPU send out PWM drive signal to power of electromagnet driving unit, and electromagnet coil generates electric current, and suspended substance is in electromagnetism
The lower movement of power control makes air gap x change, and then changes the magnetic resistance and coil current of magnetic circuit；
S2, using phase lock amplifying technology, the change in location information that will drown out in current harmonics signal extracts；
S3, according to the relationship of the amplitude and electric current of fundamental frequency driving voltage component in pwm signal, gas is calculated in CUP processor
Gap length.
4. the measurement of mutual inductance method of magnetic suspension mechanism gas length according to claim 3, which is characterized in that the movement
The calculation formula of air gap x is set to be：
In formula, N is the number of turns of electromagnet coil, μ0Indicate that space permeability, A indicate the sectional area of electromagnet core, ω0It indicates
Pulse-width signal fundamental wave angular frequency, m are the number of turns of pre-buried mutual inductor, Ui0Indicate current first harmonics signal amplitude, Uue0Indicate base
The amplitude of frequency driving voltage component, l indicate the length of iron core in magnetic circuit, μrIndicate iron core relative permeability.
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