CN108344494B - Low-frequency electromagnetic vibration table movement speed detection device based on induction coil - Google Patents
Low-frequency electromagnetic vibration table movement speed detection device based on induction coil Download PDFInfo
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- CN108344494B CN108344494B CN201810061195.9A CN201810061195A CN108344494B CN 108344494 B CN108344494 B CN 108344494B CN 201810061195 A CN201810061195 A CN 201810061195A CN 108344494 B CN108344494 B CN 108344494B
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- 238000004804 winding Methods 0.000 claims description 10
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
- G01H11/02—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by magnetic means, e.g. reluctance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/42—Devices characterised by the use of electric or magnetic means
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Abstract
The invention discloses a motion speed detection device of a low-frequency electromagnetic vibration table based on an induction coil, which comprises the induction coil, a voltage dividing unit and a signal correction unit, wherein the induction coil is wound on a moving coil of the vibration table, the voltage dividing unit is connected with the induction coil in parallel, and the output voltage of the voltage dividing unit is used as an input signal of feedback control after the frequency response is compensated by the signal correction unit. The beneficial effects of the invention are as follows: simple structure, convenient operation and reduced cost.
Description
Technical Field
The invention relates to a motion speed detection device of a low-frequency electromagnetic vibration table based on an induction coil.
Technical Field
The electromagnetic vibration table has the advantages of wide frequency range, good controllability, high output waveform precision and the like, and is widely applied to important fields of product simulation vibration environment test, vibration measurement sensor calibration and the like. In general, in order to improve the accuracy (reduce distortion) of an output waveform of an electromagnetic vibration table under a low frequency condition, a closed-loop control system is required to be constructed, and the precondition of the closed-loop control is that an output vibration signal of the electromagnetic vibration table is detected and fed back to an original driving system of the vibration table as a feedback signal, so that the vibration table is driven to move by the obtained deviation signal, and the feedback control on the accuracy of the output vibration waveform of the vibration table is realized. In general, a closed-loop control system detects an output vibration signal of a vibration table using vibration measuring sensors (displacement, velocity, and acceleration sensors). However, conventional low frequency vibration measuring sensors are expensive, bulky, and complex to install, which limits their use in low frequency electromagnetic vibration table control systems.
At present, a device for extracting the relative motion quantity of a low-frequency electromagnetic vibration table is provided, and a feedback control system is constructed based on the vibration table motion quantity extracted by the device, wherein the relative motion quantity extracting device comprises a pure resistor, a first subtracter and a first proportional amplifier; the pure resistor is connected in series with the driving coil of the vibrating table, and the total voltage drop of the pure resistor and the driving coil is input into the first subtracter as a reduced number; the voltage drop at two ends of the pure resistor is amplified by K 1 times by the first proportional amplifier and then is input into the first subtracter as a reduction number, wherein,R is the equivalent direct current resistance of the driving coil of the vibrating table, and R 1 is the resistance value of the pure resistor; the output signal of the first subtracter is used for representing the relative movement speed of the vibrating table.
The disadvantages of the above patent are:
1. The equivalent direct current resistance R of the driving coil of the vibrating table cannot be accurately measured, and in order to obtain the amplification factor K 1 of the first proportional amplifier, a relatively complex parameter adjustment process is needed, so that the use difficulty of the system is increased.
2. The device is connected with the driving coil of the vibrating table in series with a pure resistor, and an analog circuit network is constructed to extract the vibration speed signal of the vibrating table, so that the heat loss is larger and the system is more complex.
Disclosure of Invention
In order to overcome the defects of high cost, large heat loss, complex system operation and the like in the existing output vibration signal detection technology when a low-frequency electromagnetic vibration table feedback control system is constructed, the invention provides the low-frequency electromagnetic vibration table motion speed detection device based on the induction coil, which has the advantages of simple structure and convenient operation.
The technical scheme adopted by the invention is as follows:
Low frequency electromagnetic vibration platform motion speed detection device based on induction coil, its characterized in that: the device comprises an induction coil, a voltage dividing unit and a signal correction unit, wherein the induction coil is wound on a moving coil of a vibrating table, the voltage dividing unit is connected with the induction coil in parallel, and output voltage of the voltage dividing unit is used as an input signal of feedback control after frequency response is compensated by the signal correction unit.
When the driving coil on the vibrating table moving coil is electrified, the vibrating table moving coil outputs a vibrating signal, and induction voltages are generated at two ends of the induction coil. According to the law of electromagnetic induction, when the magnetic induction intensity of an air gap field where an induction coil is positioned is kept unchanged, the output induction voltage is in direct proportion to the vibration speed, however, due to the mutual inductance phenomenon between the induction coil and a driving coil, the induction voltage generates amplitude change and phase shift. The signal correction unit compensates the amplitude variation and the phase shift, then makes the voltage and the speed in direct proportion, and uses the corrected signal as the input signal of the feedback control to improve the accuracy of the feedback control.
Further, the diameter of the induction coil is much smaller than the diameter of the drive coil. Thereby increasing the number of turns and the total length of the induction coil and improving the signal-to-noise ratio of the induction voltage generated by the induction coil.
Further, the input impedance of the voltage dividing unit approaches infinity. The divider resistor approaches infinity, so that parasitic current in the induction coil is avoided, and the parasitic current is not coupled in the driving coil, so that the induction current flowing through the induction coil is as close to 0 as possible, and the interference of the induction coil on the current in the driving coil is avoided.
Further, the induction coil and the driving coil are wound on the same winding groove of the moving coil of the vibrating table, the driving coil is arranged inside, and the induction coil is arranged outside.
Or the moving coil of the vibrating table is provided with an induction coil winding groove and a driving coil winding groove, the induction coil is wound in the induction coil winding groove, and the driving coil is wound in the driving coil winding groove.
The working principle of the invention is as follows:
In general, an electromagnetic vibration table is composed of a magnetic circuit structure, a supporting suspension structure, a moving coil, etc., and when a sinusoidal input voltage is applied to a driving coil on the moving coil and a sinusoidal current is generated therein, in a uniform air-gap magnetic field generated by the magnetic circuit structure of the vibration table, a moving part of the vibration table will generate sinusoidal vibration due to the action of ampere force. According to the invention, the output vibration speed of the vibrating table is detected by winding an induction coil around a part of a uniform magnetic field area where a moving part of the vibrating table is located. In order to improve the sensitivity of the induction coil to generate induced voltage and to take into account the limitation of the size of the moving parts of the vibrating table, the wire diameter of the induction coil is designed to be much smaller than that of the driving coil, thereby increasing the number of turns and total length of the induction coil. Meanwhile, because of the mutual inductance phenomenon between the induction coil and the driving coil, the voltage output by the induction coil cannot directly represent the speed signal of the coil, and the amplitude and the phase of the voltage output by the induction coil are required to be corrected through the signal correction unit, so that the induction voltage generated at two ends of the induction coil is in direct proportion to the vibration speed output by the moving part of the vibration table, and the detection of the vibration speed output by the vibration table can be realized through detecting the corrected induction voltage.
In addition, the invention designs a voltage dividing unit for adjusting the induced voltage to be suitable for the amplitude of the signal which can be processed by the subsequent signal correction unit. The voltage dividing unit has input impedance far greater than the impedance of the induction coil, so that small induction current is generated in the induction coil, and the influence of the induction current on current in the driving coil is avoided, so that the interference on the output vibration of the moving part of the vibrating table is caused.
The vibration speed detection device of the low-frequency electromagnetic vibration table does not use an expensive speed sensor to detect the speed, so that the cost is reduced; the method of connecting the driving coil of the vibrating table in series with the pure resistor is not needed to obtain a complex circuit system of speed, so that the complex adjustment process of system parameters is avoided, and the system structure and the detection difficulty of the vibrating speed are further simplified.
The beneficial effects of the invention are as follows: simple structure, convenient operation and reduced cost.
Drawings
Fig. 1 is a schematic structural view of the present invention.
Fig. 2 is a diagram showing the same slot installation of the induction coil and the driving coil of the present invention.
Fig. 3 is a schematic diagram showing the transformation of the electric model and the mechanical model of the driving coil of the present invention.
Fig. 4 is a diagram of the drive coil and induction coil of the present invention mounted side by side.
Detailed Description
The invention will be further illustrated with reference to the following specific examples, without limiting the invention to these specific embodiments. It will be appreciated by those skilled in the art that the invention encompasses all alternatives, modifications and equivalents as may be included within the scope of the claims.
Example 1
Referring to fig. 1 and 2, the induction coil-based low-frequency electromagnetic vibration table movement speed detection apparatus includes an induction coil 12, a voltage dividing unit, and a signal correction unit. The induction coil 12 and the driving coil 11 are wound in the same winding slot of the vibrating table moving part 1 together so as to be in a uniform air-gap magnetic field, the voltage dividing unit is connected with the induction coil 12 in parallel, when the vibrating table moving part 1 outputs a vibrating signal, two ends of the induction coil 12 generate induction voltages, the induction voltages are connected with a signal correction unit at the back after passing through the voltage dividing unit, and voltage signals which are in direct proportion to the vibrating speed of the vibrating table moving part 1 are generated after being processed by the correction unit based on the inverse model of the induction coils, so that the detection of the vibrating speed output by the moving part is realized.
The working principle of the invention is as follows:
In general, an electromagnetic vibration table is composed of a magnetic circuit structure, a supporting levitation structure, a moving member, and the like, and when sinusoidal input voltage is applied to a driving coil 11 wound around the vibration table moving member 1 and sinusoidal current is generated, sinusoidal vibration is generated in the vibration table moving member 1 due to the action of ampere force in a uniform air-gap magnetic field generated by the magnetic circuit structure of the vibration table. The present invention detects the vibration table output vibration speed by winding the induction coil 12 around the portion of the vibration table moving member 1 in the uniform magnetic field region. In order to improve the signal-to-noise ratio of the induced voltage generated by the induction coil 12 and in consideration of the limitation of the size of the moving part 1 of the vibrating table, the diameter of the induction coil 12 is designed to be far smaller than that of the driving coil 11, so that the number of turns and the total length of the induction coil 12 are increased, and the sensitivity of the induction coil to extract the speed signal is improved. Further, the induced voltages at both ends of the induction coil 12 are directly proportional to the vibration speed output by the vibrating table moving part 1 after being processed by the signal correction unit based on the inverse model of the induction coil, and the detection of the vibration speed output by the vibrating table can be realized by detecting the voltage output by the signal correction unit.
In addition, the invention designs a voltage dividing unit for adjusting the induced voltage to be suitable for the amplitude of the signal which can be processed by the subsequent signal correction unit. The voltage dividing unit has extremely large input impedance, so that the induction current flowing through the induction coil 12 is close to 0, and the interference of the induction coil 12 on the output vibration of the moving part of the vibrating table is avoided.
The detection principle of the invention is as follows:
For a conventional low frequency electromagnetic vibration table, the driving coil 11 (coil length of L d) can be simplified to a series structure of a resistor R d and an inductor L d. When sinusoidal input voltage u i is applied to both ends of the driving coil 11, sinusoidal current i d is generated on the driving coil 11, and sinusoidal vibration is generated on the driving coil 11 under the action of sinusoidal ampere force under the action of a uniform air-gap magnetic field (magnetic induction intensity is B) generated by the magnetic circuit structure of the vibrating table. Since the driving coil 11 is fixedly mounted with the vibrating table moving member 1, the vibrating table moving member 1 outputs a vibration signal. Considering that the electromagnetic vibration table is a typical electromechanical coupling system, when the vibration table moving member 1 outputs vibration, the driving coil 11 generates a vibration velocity (X is the displacement of the moving part of the vibrating table,First derivative of x) is proportional to the induced electromotive force
Similarly, the induction coil 12 (length of L s) can be simplified to a series structure of the resistor R s and the inductor L s, and when the vibration table moving part 1 outputs vibration, the induction coil 12 also generates vibration speed in consideration of the coaxial installation of the induction coil 12 and the driving coil 11Proportional induced electromotive force
The voltage dividing unit of the embodiment is used for extracting the induced voltages generated at the two ends of the induction coil 12, and adjusting the voltage signals in proportion to be suitable for the amplitude of the signals which can be processed by the subsequent signal correction unit, so that the subsequent signal processing circuit is convenient to construct.
According to the steady-state magnetic circuit coupling principle, it can be assumed that the induction coil 12 and the drive coil 11 are coupled to each other by mutual inductance M. Further, the vibration process of the moving part 1 of the vibrating table can be simplified into single-degree-of-freedom vibration of a mass-spring-damping system, m, k and c are respectively equivalent mass, equivalent rigidity and equivalent damping, and as shown in figure 3, the integral electromechanical coupling relation is obtained
Where u s is the induced voltage across the induction coil 12, i s is the induced current through the induction coil 12, t is a certain time instant,AndThe first and second derivatives of x, respectively.
The impedance of the voltage dividing unit approaches infinity so that the magnitude of the induced current i s flowing through the induction coil 12 is as close to 0 as possible, i s ≡0, and further, when the vibration frequency f is low, di s/dt＝2πfis ≡0, formula (1) can be further simplified to
Based on the 1 st and 3 rd steps in (2), the input voltage u i and the output vibration speed of the vibrating table can be calculatedThe transfer function G vi between
Wherein X(s) and U i(s) are Laplacian transforms of X and U i, respectively.
Furthermore, based on equation (2), it is also possible to determine the transfer function between the input voltage u i and the induced voltage u s as
Where U s(s) is the Laplace transform of U s. Can be obtained by comparing the formula (3) with the formula (4)
Order the
As the transfer function of the signal correction unit, the vibration table output speed signal can be obtained from the induction coil output voltage according to (5). As can be seen from equation (6), the signal correction unit is a second order system, and is easily implemented by an analog circuit or a digital signal processing unit.
The vibration speed detection device of the low-frequency electromagnetic vibration table provided by the invention does not need to be connected with a driving coil of the vibration table in series to form a pure resistor and construct a complex circuit system, so that the complex adjustment process of system parameters is avoided, and the detection difficulty of the system structure and the vibration speed is further simplified. Meanwhile, the invention also reduces the construction cost of the system.
Example two
Referring to fig. 4, the present embodiment differs from the first embodiment in that: the induction coil 12 and the driving coil 11 are coaxially arranged, the induction coil 12 and the driving coil 11 are wound in different winding grooves of the vibrating table moving part 1 side by side, but are all in uniform air gap magnetic fields, the induction coil 12 and the driving coil 11 are ensured to be coaxial, and other structures and principles are the same as those of the first embodiment.
Claims (3)
1. Low frequency electromagnetic vibration platform motion speed detection device based on induction coil, its characterized in that: the device comprises an induction coil, a voltage dividing unit and a signal correction unit, wherein the induction coil is wound on a moving coil of a vibrating table, the voltage dividing unit is connected with the induction coil in parallel, and the output voltage of the voltage dividing unit is used as an input signal of feedback control after the frequency response is compensated by the signal correction unit; when a driving coil on the moving coil of the vibrating table is electrified, the moving coil of the vibrating table outputs a vibration signal, and induction voltages are generated at two ends of the induction coil; the induced voltage is connected to the signal correction unit at the back after passing through the voltage division unit, and a voltage signal proportional to the vibration speed of the moving part of the vibration table is generated after being processed by the correction unit based on the inverse model of the induction coil;
Under the condition that the magnetic induction intensity of an air gap magnetic field where the induction coil is positioned is kept unchanged, the induction voltage is in direct proportion to the vibration speed; the signal correction unit compensates the amplitude variation and the phase shift, then makes the voltage proportional to the speed, and takes the corrected signal as an input signal of feedback control; the induction coil and the driving coil are wound in the same winding groove of the vibrating table moving part together.
2. The induction coil-based low frequency electromagnetic vibration table motion speed detection apparatus according to claim 1, wherein the diameter of the induction coil is substantially smaller than the diameter of the driving coil.
3. The induction coil-based low-frequency electromagnetic vibration table movement speed detection apparatus according to claim 2, wherein the input impedance of the voltage dividing unit approaches infinity.
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| CN111351565A (en) * | 2018-12-20 | 2020-06-30 | 金顿仪器科技（昆山）有限公司 | Method and measuring module for measuring ultrasonic vibration during processing of rotating object |
| CN110081804B (en) * | 2019-05-22 | 2021-03-23 | 中国人民解放军国防科技大学 | Device and method for detecting dynamic performance of relative position sensor of maglev train |
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