CN211085273U - Differential transformer type displacement sensor - Google Patents
Differential transformer type displacement sensor Download PDFInfo
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- CN211085273U CN211085273U CN202020042422.6U CN202020042422U CN211085273U CN 211085273 U CN211085273 U CN 211085273U CN 202020042422 U CN202020042422 U CN 202020042422U CN 211085273 U CN211085273 U CN 211085273U
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- displacement sensor
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 4
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- 230000035945 sensitivity Effects 0.000 description 7
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Abstract
The utility model provides a differential transformer formula displacement sensor, its main improvement lies in, differential transformer formula displacement sensor still includes internal resistance little change compensation module RSupplement deviceA tuning network and a post-stage circuit. The tuning network is used for adjusting the relative phase between the secondary receiving signal and the primary excitation signal, and the internal resistance micro-variation compensation module RSupplement deviceThe internal resistance of each winding is subjected to micro compensation, so that the signal amplitude change caused by inductance and resistance change caused by temperature is minimized, the temperature characteristic of the L VDT winding can be improved, and the overall cost of a compensation system is reduced.
Description
Technical Field
The utility model relates to the field of electronic technology, especially, relate to a differential transformer formula displacement sensor.
Background
The differential transformer type displacement sensor (L VDT) is widely applied to various industries such as aerospace, machinery, construction, textile, railway, coal, metallurgy, plastics, chemical engineering, scientific research and the like due to the reliability and high precision of the displacement sensor, and is used for measuring elongation, vibration, object thickness, expansion and the like.
The sensor comprises a primary winding, two secondary windings, an iron core, a coil framework, a shell and the like, wherein the primary winding and the secondary windings are distributed on the framework, the iron core in a rod shape capable of moving freely is arranged in the windings, when the iron core is in a middle position, induced electromotive forces generated by the two secondary windings are equal, so that an output voltage is zero, when the iron core moves in the windings and deviates from the center position, the induced electromotive forces generated by the two windings are unequal, a voltage output exists, the voltage magnitude of the voltage output depends on the magnitude of displacement, in order to improve the sensitivity of the sensor, improve the linearity of the sensor and enlarge the linear range of the sensor, the two windings are connected in an anti-series mode, the voltage polarities of the two secondary windings are opposite, the voltage output by L VDT is the difference of the voltages of the two secondary windings, and the output voltage value is in a linear relation with the iron.
At present, on one hand, the winding is wound by adopting an alloy wire insensitive to temperature, and on the other hand, the influence generated by temperature is eliminated by carrying out mathematical processing on a signal received by the secondary winding by utilizing the symmetry of the secondary winding.
SUMMERY OF THE UTILITY MODEL
To not enough among the above-mentioned prior art, the utility model provides a differential transformer formula displacement sensor, this sensor is through adjusting the relative phase place between secondary received signal and the primary excitation signal to carry out little compensation to secondary winding internal resistance, make the inductance that arouses by the temperature, the signal amplitude variation that resistance variation leads to minimum, realized L VDT winding temperature characteristic's improvement, reduced compensating system's overall cost simultaneously.
In order to achieve the purpose, the utility model provides a differential transformer formula displacement sensor, including primary L, secondary L1, secondary L2 of winding on the skeleton, secondary L1, secondary L2 distribute along the axial of skeleton, be provided with the iron core in the skeleton, the input of primary is connected excitation signal, differential transformer formula displacement sensor still includes internal resistance little variable compensation module RSupplement deviceTuning network and post circuit, wherein:
the secondary winding L1 and the first end of the secondary winding L2 pass through an internal resistance micro-variation compensation module RSupplement deviceConnected together, a first end of the secondary winding L1 and a first end of the secondary winding L2 are homonymous ends;
the internal resistance micro-variation compensation module RSupplement deviceComprises a resistor R1 and a thermistor R connected in parallelNTC(ii) a Within a target working range, the thermistor RNTCHas negative temperature coefficient, so that the internal resistance micro-variation compensation module RSupplement deviceThe temperature characteristic with the same absolute value of the temperature coefficient of the copper wire and the opposite change trend is provided;
the tuning network is composed of a resistor and a capacitor, and forms an oscillating circuit with the secondary winding L1 and the secondary winding L2, so that the absolute value of the relative phase between the signal at the output end of the tuning network and the excitation signal is lower than +/-2 degrees;
and the post-stage circuit is connected with the output end of the tuning network, extracts an in-phase component I and an orthogonal component Q in the output signal of the tuning network according to the excitation signal, and takes the orthogonal component Q as the output signal of the differential transformer type displacement sensor.
A further improvement of the present invention is that the tuning network comprises a capacitor C4, a resistor R4, a resistor R5 and two low pass filters; the capacitor C4 is connected between two input terminals of the tuning network, and the resistors R4 and R5 are connected in series between the two input terminals of the tuning network; and two input terminals of the tuning network are respectively connected with a terminal of an output end through the two low-pass filters.
The utility model discloses a further improvement lies in, resistance R4, resistance R5's resistance value than secondary winding L1 and secondary winding L2's internal resistance is more than ten times big.
The present invention is further improved in that the low pass filter comprises a resistor and a capacitor, the resistor is connected between the input terminal and the output terminal of the tuning network; one end of the capacitor is grounded, and the other end of the capacitor is connected with an output terminal of the tuning network.
The utility model has the advantages of: the relative phase between the primary signal and the secondary signal is corrected to ensure that the detection output amplitude is maximum and the sensitivity to phase shift change caused by temperature is reduced; furthermore, the influence of temperature on internal resistance is counteracted through a compensation network, so that the temperature stability of the sensor is improved.
Drawings
Fig. 1 is a schematic diagram of the differential transformer type displacement sensor of the present invention;
FIG. 2 is a schematic diagram of a tuning network and an internal resistance delta compensation module;
FIG. 3 is a schematic diagram of a subsequent stage circuit;
fig. 4 shows the amplitude versus phase of the post-detection output signal.
Detailed Description
The following description of the preferred embodiment of the present invention will be given in detail with reference to the accompanying drawings 1, so as to better understand the functions and features of the present invention.
Referring to fig. 1, an embodiment of the present invention includes a differential transformer type displacement sensor, which includes a primary winding L, a secondary winding L1, a secondary winding L2 wound on a frame, the secondary winding L1, the secondary winding L2 distributed along an axial direction of the frame, an iron core disposed in the frame, and an input end of the primary winding connected to an excitation signalThe differential transformer type displacement sensor also comprises an internal resistance micro-variation compensation module RSupplement deviceA tuning network and a post-stage circuit. The tuning network is used for adjusting the relative phase between the secondary receiving signal and the primary excitation signal, and the internal resistance micro-variation compensation module RSupplement deviceAnd the internal resistance of each winding is subjected to micro compensation, so that the signal amplitude change caused by inductance and resistance change caused by temperature is minimum.
Specifically, the first ends of the secondary winding L1 and the secondary winding L2 pass through the internal resistance micro-variation compensation module RSupplement deviceConnected together, the first ends of secondary winding L1 and secondary winding L2 are homonymous ends.
As shown in fig. 1 and 2, the internal resistance micro-variation compensation module RSupplement deviceComprises a resistor R1 and a thermistor R connected in parallelNTC(ii) a Within a target operating range, the thermistor RNTCHas negative temperature coefficient, so that the internal resistance slightly changes the compensation module RSupplement deviceThe temperature characteristics are the same as the absolute value of the temperature coefficient of the copper wires of the primary winding L and the secondary windings L1, L2 and have opposite change trends.
Thermistor RNTCUsually made of semiconductor material. In this embodiment, the thermistor R is selected by experiment or simulationNTC. In the selection process, firstly, the internal resistance change curve of each winding under the temperature change is measured, and then the thermistor R with corresponding temperature characteristic is selected according to the internal resistance change curveNTC. In the thermistor RNTCThe upper parallel resistor R1 has the function that the internal resistance curve of the copper wire of the common winding is close to a straight line, and the thermistor RNTCThe internal resistance change curve is a curve, and the internal resistance micro-variation compensation module R can be realized by connecting resistors in parallelSupplement deviceThe resistance value of the transformer is closer to a straight line along with the variation of the temperature and the variation of the internal resistance of the winding along with the temperature. Internal resistance micro-variation compensation module RSupplement deviceNot only for compensating the secondary winding L1 and the secondary winding L2, but also for compensating the signal amplitude variation caused by the temperature variation of the internal resistance of the primary winding L, which is complicated, in the internal resistance micro-variation compensation module RSupplement deviceMultiple iterations may be employed until the temperature-induced resistance change is minimized during the element selection process.
The second ends of secondary winding L1 and secondary winding L2 are connected to two input terminals of a tuning network, respectively, the tuning network is composed of a resistor and a capacitor, and the tuning network, secondary winding L1 and secondary L2 constitute an oscillator circuit, so that the absolute value of the phase difference between the signal at the output end of the tuning network and the excitation signal is in the range of + -2 DEG or 178-182 DEG, the tuning network corrects the relative phase between the primary and secondary signals, maximizes the detection output amplitude, and reduces the sensitivity to the phase shift variation caused by temperature.
The tuning network comprises a capacitor C4, a resistor R4, a resistor R5 and two low-pass filters, wherein the capacitor C4 is connected between two input terminals of the tuning network, the resistor R4 and the resistor R5 are connected between the two input terminals of the tuning network in series, the two input terminals of the tuning network are respectively connected with terminals of an output end through the two low-pass filters, the resistance values of the resistor R4 and the resistor R5 are more than ten times (one order of magnitude) larger than the internal resistance of the secondary winding L1 and the secondary winding L2 so as to balance the sensitivity of signal sensitivity and internal resistance change, and the Q value of the oscillating circuit is reduced by the resistors R4 and R5, so that the circuit is not easily influenced by the change of the inductance and the resistance of the L VDT winding.
The low-pass filter comprises a resistor R34/R35 and a capacitor C24/C25, and the resistor R34/R35 is connected between the input terminal and the output terminal of the tuning network; one end of the capacitor C24/C25 is grounded, and the other end is connected to the output terminal of the tuning network. The pair of R34/C24 and R35/C25 combined into an RC filter can reduce the signal bandwidth while providing the extra degree of freedom needed to adjust the circuit phase so that the maximum output of the post-detection circuit occurs at 0 ° or 180 ° relative phase shift.
In the process of adjusting the parameters of the tuning network, a capacitor C4, a resistor R34/C24 and a resistor R35/C25 are required to be adjusted to form parallel resonance with L1 and L2 by adjusting C4, meanwhile, the phase is advanced, and the phase is adjusted to be retarded by adjusting R34/C24 and R35/C25. when the iron core is in a full-scale position, the iron core needs to be in a resonance state, the advance amount and the retard amount are both considered, the output signal of the tuning network cannot lead or retard excessively, the full-scale position is half of a measuring stroke, namely, if the measuring stroke of the L VDT sensor is L, the iron core is moved to L/2 distance in one direction by taking the electrical zero point of L VDT as the origin (at this time, the iron core is symmetrical to the origin), and the iron core is in the full-scale position at this time.
The post-stage circuit is connected with the output end of the tuning network, extracts an in-phase component I and an orthogonal component Q in the output signal of the tuning network according to the excitation signal, and uses the orthogonal component Q as the output signal of the differential transformer type displacement sensor.
The schematic diagram of the latter stage circuit is shown in fig. 3, and includes two multipliers to which the output signals of the tuning network are respectively output. In addition, the excitation signal is output as a reference signal to one multiplier while delaying the phase of the excitation signal by 90 °, and the input value is input to the other multiplier, which causes the former multiplier to obtain an in-phase component I and the latter multiplier to obtain a quadrature component Q.
In order to obtain the parameters of the tuning network, the signals of the resonant circuit are connected into a rear-stage circuit, an L VDT iron core is placed at a position close to the full scale, the parameters in the rear-stage circuit are adjusted to ensure that the relative phase difference between a reference signal and an input signal is respectively 0 DEG and 90 DEG, in-phase (I) and quadrature (Q) output signals are measured, the parameters in the rear-stage circuit are adjusted, namely, the rear-stage circuit has two output signals I and Q, two output channels cannot be simultaneously opened, so that the parameters in the rear-stage circuit are required to be adjusted to gate the output signals I and Q, the influence of the amplitude and phase change can be separated after the I and Q components are obtained, the amplitude and the relative phase are calculated according to a formula in the figure, the parameters of the tuning network are adjusted until the absolute value of the relative phase is lower than +/-2 DEG, the absolute value of the relative phase means that the phase difference of two sinusoidal signals ranges from +/-2 DEG or from-178 DEG to-182 DEG, and the absolute value of the relative phase is calculated byrealIt is found that the phase value calculated by the above calculation-only method is a positive number, and is therefore referred to as a relative phase.
As shown in fig. 4, the circuit network parameters are configured so that the input signal is at 0 ° or 180 ° from the reference signal phase, and the detected output has the greatest signal sensitivity and the least phase sensitivity in the vicinity of this position. In fig. 4, the dashed line represents the amplitude versus phase of the output signal.
The present invention has been described in detail with reference to the embodiments shown in the drawings, and those skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details of the embodiments should not be construed as limitations of the invention, which are intended to be covered by the following claims.
Claims (4)
1. A differential transformer type displacement sensor comprises a primary winding L, a secondary winding L1 and a secondary winding L2 which are wound on a framework, wherein the secondary winding L1 and the secondary winding L2 are distributed along the axial direction of the framework, an iron core is arranged in the framework, the input end of the primary winding is connected with an excitation signal, and the differential transformer type displacement sensor is characterized by further comprising an internal resistance micro-variation compensation module RSupplement deviceTuning network and post circuit, wherein:
the secondary winding L1 and the first end of the secondary winding L2 pass through an internal resistance micro-variation compensation module RSupplement deviceConnected together, a first end of the secondary winding L1 and a first end of the secondary winding L2 are homonymous ends;
the internal resistance micro-variation compensation module RSupplement deviceComprises a resistor R1 and a thermistor R connected in parallelNTC(ii) a Within a target working range, the thermistor RNTCHas negative temperature coefficient, so that the internal resistance micro-variation compensation module RSupplement deviceThe temperature characteristic with the same absolute value of the temperature coefficient of the copper wire and the opposite change trend is provided;
the tuning network is composed of a resistor and a capacitor, and forms an oscillating circuit with the secondary winding L1 and the secondary winding L2, so that the absolute value of the relative phase between the signal at the output end of the tuning network and the excitation signal is lower than +/-2 degrees;
and the post-stage circuit is connected with the output end of the tuning network, extracts an in-phase component I and an orthogonal component Q in the output signal of the tuning network according to the excitation signal, and takes the orthogonal component Q as the output signal of the differential transformer type displacement sensor.
2. The differential transformer displacement sensor of claim 1, wherein the tuning network comprises a capacitor C4, a resistor R4, a resistor R5, and two low pass filters; the capacitor C4 is connected between two input terminals of the tuning network, and the resistors R4 and R5 are connected in series between the two input terminals of the tuning network; and two input terminals of the tuning network are respectively connected with a terminal of an output end through the two low-pass filters.
3. The differential transformer displacement sensor of claim 2, wherein the resistances of R4 and R5 are more than ten times greater than the internal resistances of secondary winding L1 and L2.
4. A differential transformer displacement sensor according to claim 2, wherein the low pass filter comprises a resistor and a capacitor, the resistor being connected between the input and output terminals of the tuning network; one end of the capacitor is grounded, and the other end of the capacitor is connected with an output terminal of the tuning network.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202020042422.6U CN211085273U (en) | 2020-01-09 | 2020-01-09 | Differential transformer type displacement sensor |
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| CN202020042422.6U CN211085273U (en) | 2020-01-09 | 2020-01-09 | Differential transformer type displacement sensor |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111121831A (en) * | 2020-01-09 | 2020-05-08 | 上海兰宝传感科技股份有限公司 | Differential transformer type displacement sensor |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111121831A (en) * | 2020-01-09 | 2020-05-08 | 上海兰宝传感科技股份有限公司 | Differential transformer type displacement sensor |
| CN111121831B (en) * | 2020-01-09 | 2024-08-06 | 上海兰宝传感科技股份有限公司 | Differential transformer type displacement sensor |
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