CN205450161U - 6 line system LVDT detection circuitry that breaks based on AD698 uses - Google Patents
6 line system LVDT detection circuitry that breaks based on AD698 uses Download PDFInfo
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- CN205450161U CN205450161U CN201521086720.0U CN201521086720U CN205450161U CN 205450161 U CN205450161 U CN 205450161U CN 201521086720 U CN201521086720 U CN 201521086720U CN 205450161 U CN205450161 U CN 205450161U
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Abstract
The utility model discloses a 6 line system LVDT detection circuitry that breaks based on AD698 uses provides the function of a peripheral circuit in order to realize the broken string detection, and a signal outside the normal range can be exported to the circuit under the assurance broken string condition for signal collector can discern this wrong signal, and makes corresponding processing. According to the utility model discloses, the LVDT broken string detection circuitry who uses based on AD698 comprises former limit broken string detection circuitry, vice limit broken string detection circuitry and false signal generating circuit. Former limit broken string detection circuitry adopts current detection, and the current induction amplifier is gone into to the cluster on former sideline way to do half -wave filtering to output signal, through detecting filtered output voltage in order to confirm whether the circuit breaks off. Because the current induction amplifier that uses is unipolar, the former limit signal of AD698 output be sinusoidal signal, consequently be the half -wave signal through the output signal of CF post -filter, because the sampling resistor RS that the cluster is gone into is the resistance that the resistance is very little, grade adds an amplifier circuit after more for this reason.
Description
Technical field
This utility model relates to industrial control field, particularly relates to a kind of 6 line LVDT break detection circuits based on AD698 application.
Background technology
At present LVDT measures the method for displacement and has obtained using widely in big machinery system, when after working long hours it is possible that aging circuit is so that circuit situation about disconnecting.If can not detecting this situation well, can continue because of the induced voltage on circuit and produce the error result in the normal range, affect system work.
AD698 is to use at present a relatively broad LVDT signal condition chip, compares conventional signal conditioning circuit, and application based on AD698 has only to extend the peripheral circuit of fraction and can be realized as the signal condition of LVDT.But AD698 chip itself does not have the function of burn out detection.
Therefore, those skilled in the art is devoted to develop a kind of peripheral expansion circuit based on AD698 application, to realize the detection to LVDT broken string situation.
Utility model content
Because the drawbacks described above of prior art, technical problem to be solved in the utility model is the function that AD698 chip itself does not have burn out detection.
nullFor achieving the above object，This utility model provides a kind of 6 line LVDT break detection circuits based on AD698 application，Including former limit burn out detection module、Secondary burn out detection module and rub-out signal generation module，Described former limit burn out detection module includes electric current induction amplifier、Sampling resistor RS、Filter capacitor CF、First operational amplifier OPA and resistance R1、Resistance R2、Resistance R3，Wherein sampling resistor RS series connection accesses the former sideline pass foot of AD698，Two inputs of electric current induction amplifier are connected across the two ends of sampling resistor RS，The output termination filter capacitor CF of electric current induction amplifier，One end of the other end connecting resistance R1 of filter capacitor CF and the positive input terminal of the first operational amplifier OPA，The other end ground connection of resistance R1，The negative input end connecting resistance R2 of the first operational amplifier OPA and one end of resistance R3，The other end ground connection of resistance R2，Another of resistance R3 terminates the outfan of the first operational amplifier；Described rub-out signal generation module includes resistance R5, wherein the secondary side signal input pin of a termination AD698 of resistance R5, and the other end of resistance R5 loads a d. c. voltage signal；Described secondary burn out detection module includes comparator CMPA, second operational amplifier OPA and electric capacity C1, resistance R6, resistance R7, resistance R8, resistance R9, wherein one end ground connection of resistance R8, another positive input terminal terminating the second operational amplifier OPA and one end of resistance R6 of resistance R8, another termination input signal and one end of electric capacity C1 of resistance R6, one end of the other end connecting resistance R7 of electric capacity C1, another of resistance R7 terminates the negative input end of the second operational amplifier OPA, the negative input end of the output termination comparator CMPA of the second operational amplifier OPA, the comparison reference voltage pin of the positive input termination AD698 of comparator CMPA, the two ends of resistance R9 are connected across negative input end and the outfan of the second operational amplifier OPA.
Further, described electric current induction amplifier is the INA195 chip of TI company.
Further, described first operational amplifier OPA and the second operational amplifier OPA is OPA2277.
Further, described comparator CMPA is LM293.
Further, the resistance value of described sampling resistor RS is 3.9 Ω.
Further, the capacitance of described electric capacity CF is 0.1 μ F.
Further, the capacitance of described electric capacity C1 is 1 μ F.
Further, the resistance value of described resistance R1, R2, R3 is 20k Ω.
Further, the resistance value of described resistance R5 is 100k Ω.
Further, the resistance value of described resistance R6, R7 is 5.1k Ω, and the resistance value of described resistance R8, R9 is 300k Ω.
AD698 has only to extend several resistance and capacity cell can realize the signal condition of LVDT, but due to the disappearance of burn out detection function, it is impossible to meet the demand of a lot of application scenario.For this, two kinds of methods of proposition are respectively used to detect the former limit of LVDT and whether secondary breaks.
The former limit of LVDT is produced a pumping signal by AD698 chip, is generally a sinusoidal signal, former sideline road has electric current and flows through, and in the case of broken string, both sides pin still exists voltage, but does not have electric current under open circuit conditions and flow through.Detecting for this on circuit has no current can realize the burn out detection on former limit.Former sideline road seals in sampling resistor, and through amplifying and after conditioning, i.e. can be used for detecting.
Signal on the secondary of LVDT is produced by the sensing of former limit, and the method for current detecting is also applied for herein, but the difference of LVDT parameter is likely to result in result difference, it is difficult to sampling.Use the mode of superposed signal to detect the broken string situation of LVDT secondary for this.In the application of AD698, four-wire system LVDT and six line LVDT are the same, and only two outlets are connected with the pin of AD698 chip, and the two pin is all the input of difference high resistant, as long as so adding a signal on a pin, another one pin detecting signal.
Below with reference to accompanying drawing, the technique effect of design of the present utility model, concrete structure and generation is described further, to be fully understood from the purpose of this utility model, feature and effect.
Accompanying drawing explanation
Fig. 1 is the former limit break detection circuit figure of a preferred embodiment of the present utility model；
Fig. 2 is the partial circuit diagram needing application former to AD698 to make amendment in the secondary break detection circuit of a preferred embodiment of the present utility model；
Fig. 3 is the secondary break detection circuit figure of a preferred embodiment of the present utility model；
Fig. 4 is the former limit break detection circuit figure of the amendment of a preferred embodiment of the present utility model；
Fig. 5 is the local circuit schematic diagram of AD698 application in prior art；
Fig. 6 is the local circuit schematic diagram of the amended AD698 application of a preferred embodiment of the present utility model.
Detailed description of the invention
In view of the defect described in foregoing teachings, target of the present utility model is to design one peripheral circuit of offer to realize the function of burn out detection for AD698, to ensure the signal outside circuit can export a normal range in the case of breaking, make signal picker be capable of identify that the signal of this mistake, and make respective handling.According to this utility model, LVDT break detection circuit based on AD698 application is made up of former limit break detection circuit, secondary break detection circuit and rub-out signal generation circuit.
Described former limit break detection circuit uses the method for current detecting, seals in electric current induction amplifier, and output signal is done half-wave filtering on the road of former sideline, by detection filter output voltage to confirm whether circuit disconnects.Such as Fig. 1, wherein L is primary coil, RS is to seal in the sampling resistor on the road of former sideline, Sensor is electric current induction amplifier, electric current induction amplifier used herein can with but be not limited to use TI company INA195 chip, CF is filter capacitor, R1, R2, R3 are the resistance in circuit, constituting amplifying circuit with operational amplifier OPA, EXC1 with EXC2 connects network corresponding in AD698 application, and OUT is the output signal of testing circuit.Electric current induction amplifier owing to using is unipolar, the former limit signal of AD698 output is sinusoidal signal, therefore through the filtered output signal of CF be half-wave voltage signal, sampling resistor RS owing to being serially accessed to the circuit is the resistance that a resistance is the least, therefore output signal is likely to less, adds an amplifying circuit for this in rear class.
As it is shown in figure 1, output signal OUT should be a half-wave voltage signal, have been provided with preliminary detected ability, but its parameter such as amplitude, frequency has ambiguity, for more preferable effect can be obtained in Digital Detecting Method, this is added a comparator in rear class, as shown in Figure 4.Output signal OUT during wherein input signal SIN is Fig. 2, VCMP2 is comparison reference voltage, in application, we select the voltage of an about 1V, right output signal CHK1 is output signal, the level of cause digital sampling circuitry in actual applications cannot determine, and at this is open-drain output, so this signal does not pulls up in testing circuit, keep its open-drain state, it is possible to prevent the input overpressure situation in subsequent design from occurring.
CHK1 signal is normally a square-wave signal on former limit herein, and dutycycle is slightly larger than 50%, depending on its frequency is according to driving frequency in AD698 application；And in the case of breaking in former limit, no signal produces herein.Subsequent logic design can use the method for pulse detection to detect the broken string situation on the former limit of LVDT.
Described secondary testing circuit uses the method for additional signal detection, at one signal of superposition of secondary, detects at another side.Four signal input pins of the secondary of AD698 chip are all high resistant inputs, wherein one d. c. voltage signal of mode superposition of a pin pull-up, as in figure 2 it is shown, be the Signal averaging part in secondary testing circuit.In Fig. 2, R5 is pull-up resistor, and VOFFSET is the d. c. voltage signal of institute's superposition, and the size of this signal determines after according to line length, this calculates decay.
Fig. 3 show the detection part in secondary testing circuit, and CMPA is comparator, and OPA is operational amplifier, C1 is filter capacitor, and IN is circuit input signal, is connected with the other end of the secondary of LVDT, VCOMP, for comparing voltage, determines according to actual track decay, and OUT is output signal.Wherein C1 Yu R6～R9, OPA form a low pass filter, for taking out superposition d. c. voltage signal on the line, when broken string occurs, will be unable to this direct current signal be detected, so being judged as broken string.
In foregoing circuit, utilize the OUT signal gone out belonging to CMPA to drive an audion, to control the pull-up of the OFF1 pin current potential to AD698, the amendment to AD698 output voltage can be realized, to guarantee to export the voltage outside the normal range in the case of broken string.
Circuit as shown in Figure 3, because of superposition is negative level, and in the case of secondary does not breaks, output signal OUT is high-impedance state；And in the case of broken string, output signal OUT is low level, utilizes this feature, AD698 application circuit is made part and revises such as Fig. 5 and Fig. 6.
Being contrasted by Fig. 5 and Fig. 6, Fig. 5 is the local circuit schematic diagram of AD698 application under normal circumstances, and Fig. 6 is amended circuit theory diagrams, and amendment content increases audion Q1, resistance R12 and R13 herein.By described above, the OUT in SIN with Fig. 3 is connected, then the audion Q1 conducting when broken string, OFF1 current potential is pulled up, biasing is by upper shifting, and the output voltage of AD698 will be pulled to outside normal range, then the magnitude of voltage collected by analogue signal acquisition circuit both can be used to judge broken string situation.
Result for above circuit detects, and i.e. can determine that broken string state and makes respective handling.
Preferred embodiment of the present utility model described in detail above.Should be appreciated that the ordinary skill of this area just can make many modifications and variations according to design of the present utility model without creative work.Therefore, all technical staff in the art pass through the available technical scheme of logical analysis, reasoning, or a limited experiment on the basis of existing technology according to design of the present utility model, all should be in the protection domain being defined in the patent claims.
Claims (10)
- null1. 6 line LVDT break detection circuits based on AD698 application，It is characterized in that，Including former limit burn out detection module、Secondary burn out detection module and rub-out signal generation module，Described former limit burn out detection module includes electric current induction amplifier、Sampling resistor RS、Filter capacitor CF、First operational amplifier OPA and resistance R1、Resistance R2、Resistance R3，Wherein sampling resistor RS series connection accesses the former sideline pass foot of AD698，Two inputs of electric current induction amplifier are connected across the two ends of sampling resistor RS，The output termination filter capacitor CF of electric current induction amplifier，One end of the other end connecting resistance R1 of filter capacitor CF and the positive input terminal of the first operational amplifier OPA，The other end ground connection of resistance R1，The negative input end connecting resistance R2 of the first operational amplifier OPA and one end of resistance R3，The other end ground connection of resistance R2，Another of resistance R3 terminates the outfan of the first operational amplifier；Described rub-out signal generation module includes resistance R5, wherein the secondary side signal input pin of a termination AD698 of resistance R5, and the other end of resistance R5 loads a d. c. voltage signal；Described secondary burn out detection module includes comparator CMPA, second operational amplifier OPA and electric capacity C1, resistance R6, resistance R7, resistance R8, resistance R9, wherein one end ground connection of resistance R8, another positive input terminal terminating the second operational amplifier OPA and one end of resistance R6 of resistance R8, another termination input signal and one end of electric capacity C1 of resistance R6, one end of the other end connecting resistance R7 of electric capacity C1, another of resistance R7 terminates the negative input end of the second operational amplifier OPA, the negative input end of the output termination comparator CMPA of the second operational amplifier OPA, the comparison reference voltage pin of the positive input termination AD698 of comparator CMPA, the two ends of resistance R9 are connected across negative input end and the outfan of the second operational amplifier OPA.
- 2. the 6 line LVDT break detection circuits applied based on AD698 as claimed in claim 1, it is characterised in that described electric current induction amplifier is the INA195 chip of TI company.
- 3. the 6 line LVDT break detection circuits applied based on AD698 as claimed in claim 1, it is characterised in that described first operational amplifier OPA and the second operational amplifier OPA is OPA2277.
- 4. the 6 line LVDT break detection circuits applied based on AD698 as claimed in claim 1, it is characterised in that described comparator CMPA is LM293.
- 5. the 6 line LVDT break detection circuits applied based on AD698 as claimed in claim 1, it is characterised in that the resistance value of described sampling resistor RS is 3.9 Ω.
- 6. the 6 line LVDT break detection circuits applied based on AD698 as claimed in claim 1, it is characterised in that the capacitance of described electric capacity CF is 0.1 μ F.
- 7. the 6 line LVDT break detection circuits applied based on AD698 as claimed in claim 1, it is characterised in that the capacitance of described electric capacity C1 is 1 μ F.
- 8. the 6 line LVDT break detection circuits applied based on AD698 as claimed in claim 1, it is characterised in that the resistance value of described resistance R1, R2, R3 is 20k Ω.
- 9. the 6 line LVDT break detection circuits applied based on AD698 as claimed in claim 1, it is characterised in that the resistance value of described resistance R5 is 100k Ω.
- 10. the 6 line LVDT break detection circuits applied based on AD698 as claimed in claim 1, it is characterised in that the resistance value of described resistance R6, R7 is 5.1k Ω, and the resistance value of described resistance R8, R9 is 300k Ω.
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| CN201521086720.0U CN205450161U (en) | 2015-12-23 | 2015-12-23 | 6 line system LVDT detection circuitry that breaks based on AD698 uses |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109541386A (en) * | 2018-11-29 | 2019-03-29 | 厦门阳光恩耐照明有限公司 | A kind of alternating current-direct current driving detection device |
| CN110907863A (en) * | 2019-12-10 | 2020-03-24 | 湖南优利泰克自动化系统有限公司 | Analog input channel wiring state detection method and system |
-
2015
- 2015-12-23 CN CN201521086720.0U patent/CN205450161U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109541386A (en) * | 2018-11-29 | 2019-03-29 | 厦门阳光恩耐照明有限公司 | A kind of alternating current-direct current driving detection device |
| CN110907863A (en) * | 2019-12-10 | 2020-03-24 | 湖南优利泰克自动化系统有限公司 | Analog input channel wiring state detection method and system |
| CN110907863B (en) * | 2019-12-10 | 2022-01-07 | 湖南优利泰克自动化系统有限公司 | Analog input channel wiring state detection method and system |
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