RU2352059C1 - Shaper of impulses from signals of induction data units of rotation frequency - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention can be used in systems of self-acting measuring, guidance and emergency protection into which composition the data units developing pulsing signals, in particular, induction data units of a rotation frequency and the rate of flux enter. In device measuring volt-second of the area of half-wave of each signal of the data unit of rotation frequency and its comparison with part of the area of a similar half-wave of previous signal is carried out. The shaper contains the integrator (3), the peak detector (4), three threshold devices (1, 7, 10), two keys (2, 8), device AND (11), univibrator (12) and three resistors (5, 6, 9).

EFFECT: increase of reliability and noise stability of the shaper of impulses from signals of induction data units of rotation frequency.

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Description

The present invention relates to measuring equipment and can be used in automatic measurement, control and emergency protection systems, which include sensors that generate pulsed signals, in particular induction sensors of speed and flow.

A device [1] is known, which generates pulses from unipolar sensor signals, and the magnitude of the threshold for the formation of each pulse is determined by the amplitude of the signal preceding it.

The considered analog device contains two amplitude detectors, resistor voltage dividers, a comparator, a key, an OR-NOT element, a trigger, AND-NOT and OR elements.

A significant disadvantage of this device is that it does not allow the formation of pulses in a wide range of amplitudes of the input signals, since lowering the threshold necessary for low-level signals reduces the noise immunity of the device.

The closest in technical essence and achievable positive effect is the device adopted for the prototype [2], which measures the volt-second area S _{2 of the} negative half-wave of each signal of the induction speed sensor and compares the obtained values of S ₂ with the threshold value S _por1 = Q · S _1k equal to the part of the volt-second area S _{1k of the} same half-wave of the previous sensor signal. The required impulse is formed when the conditions S _1к > S _{пр .min} , S ₂ > S _por1 ,

where S _pr.min - the maximum minimum allowable value of the volt-second area of the investigated half-wave sensor signals.

The structure of the prototype device (figure 1) includes the first 1, second 7 and third 10 threshold elements, first 2, second 8 and third 14 keys, integrator 3, amplitude detector 4, first 5 and second 6 resistors, circuit 11, single vibrators 12.15 and capacitor 13.

Significant disadvantages of the device in question are low reliability and noise immunity, which is due to the following.

In the prototype device, the integrator 3 measures the volt-second areas S of the investigated half-wave signals. In this case, the voltage u (3) is generated at the output of the integrator 3, the value of which is proportional to the volt-second area S, and this voltage is stored on the capacitor C (4-3) of the amplitude detector 4 (Fig. 2).

Suppose that during the operation of the prototype device on the capacitor C (4-3), the voltage u ₁ (4) was remembered, and at the output of the resistor voltage divider, consisting of resistors 5 and 6, a threshold voltage u _por1 (10) was _generated that determines the threshold the inclusion of element 10 and the equivalent threshold S _por1 .

When the negative half-wave of the next signal e _c2 arrives, the voltage u ₂ (3) proportional to the volt-second area S _{2 of} this half-wave will be generated at the output of the integrator 3. When the voltage u ₂ (3) _{reaches the} value of u _por1 (10), a pulse u ₂ (10) will appear at the output of the threshold element 10 with a duration equal to the time during which the voltage u ₂ (3) of the integrator 3 will exceed the threshold voltage u _por1 (10).

At the leading edge of the pulse u ₂ (10), a single-shot 12 will be started, the signal of which u ₂ (12) will open the key 8, and the capacitor C (4-3) will be subdischarged. At the trailing edge of the pulse u ₂ (10), the one-shot 15 will be started and the key 14 will open, as a result of which the capacitor 13 will discharge.

At the end of the signal e _c2 , the threshold voltage u _por2 (10), equivalent to the threshold S _por2 , is established at the output of the resistor divider.

If subsequently, the signal e _cz arrives at the input of the prototype device, the volt-second area S _{3 of} which slightly exceeds the threshold S _por2 , which is quite possible, then a very short pulse u ₃ will be generated at the output of the threshold element 10 (10).

On the leading and trailing edges of the short pulse will be started monostable multivibrator 12 and 15. Since in this case the pulse width monostable multivibrators 12 and 15 is much greater than the pulse width u ₃ (10), during the time τ _p the pulses will simultaneously act monostable multivibrators 12 and 15 opening keys 8 and 14.

When this occurs, the discharge of the capacitor C (4-3) of the amplitude detector 4 through the public keys 8 and 14 by the current I _p (Fig.2). The magnitude of this current will be unacceptably large, since it is determined by the low resistance of the public keys 8 and 14. The voltage across the capacitor C (4-3) and, therefore, the threshold U _pore3 (10) of the formation of the required pulses will decrease to almost 0 V.

In this case, the threshold for the formation of the next pulse will be the threshold for switching on the element 7 u _on (7), equivalent to the threshold S _{pr min} , and the capacitor C (4-3) of the amplitude detector 4 will not have time to charge from 0 V when the device is operating at a high frequency of a given range to the maximum voltage value at the output of the integrator 3, equivalent to the area of the next pulse. Therefore, the repetition periods of the next generated pulse and the pulse following it will differ significantly from the periods of the corresponding signals e _{from the} sensor, which is equivalent to a malfunction of the prototype device.

The prototype device uses a relatively complex sub-discharge scheme of the capacitor C (4-3) of the amplitude detector 4: it requires two one-shots, two keys, a capacitor 13, and its operation cycle consists of two clock cycles - the capacitor sub-cycle C (4-3) and a clock discharge capacitor 13.

In addition, in the prototype device, the duration of the generated pulses u (11) has a variable value, the minimum value of which is 0 sec, which leads to the need to complicate the subsequent circuit receiving such pulses.

The above disadvantages lead to a decrease in the reliability of the prototype device.

The low noise immunity of the prototype device is due to the fact that in it the threshold for switching on the element 1 u _on (1) is only a few millivolts. In the presence of even small low-frequency interference in the device under consideration, uncontrolled switching of element 1 and ultimately the formation of false pulses can occur.

The technical result to which the claimed invention is directed is to increase the reliability and noise immunity of the pulse shaper from the signals of induction speed sensors.

To achieve this result, in a pulse shaper from signals of induction speed sensors containing an integrator, an amplitude detector, three threshold elements, two keys, an I element, a one-shot and two resistors, the shaper input being connected to the integrator input and through the first threshold element to the control the input of the first key, the outputs of which are connected to the inputs of the integrator connected to the terminals of the capacitor of the integrator, the output of the integrator is connected to the first input of the third threshold element and the input the house of the amplitude detector, the output of which is connected to the input of the second threshold element, the first output of the second key and through the first resistor to the second input of the third threshold element and the first output of the second resistor, the second output of which is connected to a common bus, the output of the third threshold element is connected to the first input element And, the second input of which is connected to the output of the second threshold element, the output of the one-shot is connected to the control input of the second key, in contrast to the prototype:

1. A tritium resistor is introduced, and the second output of the second key is connected through a third resistor to a common bus, the output of the And element is connected to the input of a single-shot, the output of which is connected to the output of the driver.

2. The threshold for switching on the first threshold element is set equal to 30-50% of the minimum amplitude value of the investigated half-wave signals of the induction speed sensors.

In the proposed pulse shaper from the signals of the induction speed sensors, the sub-discharge circuit of the capacitor C (4-3) of the amplitude detector 4 is simplified: it does not require the use of a capacitor 13, a key 14, and a single-vibrator 15. In this circuit (Fig. 3), the newly introduced resistor 9 together with key 8 forms a sub-discharge circuit of capacitor C (4-3). This completely eliminates the possibility of the occurrence of large discharge currents of the capacitor C (4-3), lowering the voltage of the threshold u of the _pores (10) of the pulse formation to 0 V and a malfunction of the proposed device. In the new capacitor sub-discharge scheme C (4-3), the voltage across this capacitor (at the output of the amplitude detector 4) decreases exponentially u (4) = u _max (4) · e ^{-t / (R · C)} during the time interval τ _and (12). The value of the newly introduced resistor 9 is determined by the formula:

The newly introduced connection of the one-shot 12 with the output of the element And 11 and the output of the proposed pulse shaper provide the formation of the desired pulse with a constant duration τ _and (12).

In the proposed pulse shaper, the threshold for switching on the element 1 u _on (1) is set equal to 30-50% of the minimum amplitude value of the studied half-wave signals. So, for example, if it is necessary to generate pulses from signals in the range of rotation speed from n _min = 1000 to n _max = 50,000 rpm and it is known that in this range the sensor generates signals with an amplitude of 0.15-10 V [3], [ 4], then the threshold u _on (1) is rationally set to 0.15 V · (0.3-0.5) = 45-75 mV≈60 mV (Fig. 4).

In this case, the measured area will be at least 80% of the entire area of the studied half-waves of signals, which is quite acceptable, since in the proposed device the main criterion in the formation of the required pulses is not the half-wave square of the signals, but the difference in the half-wave areas of adjacent signals.

Thus, all the distinguishing features given in the formula of the proposed pulse shaper from the signals of the induction speed sensors allow us to conclude that the claimed technical solution meets the criterion of "novelty." These signs were not identified in other technical solutions when studying this and related areas of technology, they allow to obtain a new quality and a significant difference: they provide high reliability and noise immunity of the proposed pulse shaper from the signals of induction speed sensors.

In the text of the description and figure 1-6 adopted the following notation and abbreviations:

shaper - pulse shaper - pulse shaper from signals of induction speed sensors;

sensor - induction speed sensor;

required pulse - a pulse generated by the proposed device from the sensor signals;

e _c is the sensor signal;

e _pom - interference signal;

A, A _min , A _max - the amplitude of the studied signals and its minimum and maximum values in the range of rotation speed n _min -n _max ;

S - signal area - volt-second area of the studied signal half-wave;

S ₁ , S ₂ , S _1k , S _2k - respectively, obtained in the process of measuring the volt-second areas of the first and second studied half-waves of signals and the maximum (final) values of these areas;

S _then - the area of the signal equal to the threshold of pulse formation;

Q is a coefficient defining a part of the area S _1k , making up the threshold S _por1 = Q · S _1k , with Q <1;

S _{pr min} - the maximum minimum allowable area of the sensor signal;

S _n , S _min , S _max , ΔS - respectively, the nominal, minimum and maximum values of the signal area, as well as the maximum deviation of this area from its nominal value S _n ;

designations of the type u (1), u (3), u (12) - the output voltage, respectively, of the threshold element 1, integrator 3, one-shot 12, and u (3) is equivalent to the area of the signal S;

u _pore (10) is the voltage equal to the threshold for switching on the element 10, it is also equal to the threshold for the formation of the required pulse, and u _pore (10) is equivalent to S _pore

u _on (1), u _on (7) is the voltage equal to the switching threshold of elements 1 and 7, respectively, and u _on (7) is equivalent to S _av.min ;

C (4-3) - capacitor 3 of the amplitude detector 4 or its capacity;

τ _and (12) is the duration of the pulse of a single vibrator 12, it is the duration of the required pulse generated by the proposed device;

τ _p is the time during which the keys 8 and 14 are simultaneously closed;

I _p - current flowing through simultaneously closed keys 8 and 14;

Z is the number of pathogens on the rotor of the studied object;

K is a coefficient determining to what level it is necessary to lower the voltage on the capacitor C (4-3) so that you can remember on this capacitor the new voltage value obtained in the integrator 3, and K <1;

ln K is the natural logarithm of the coefficient K.

The essence of the invention is illustrated in figures 1-6, which show:

figure 1 is a block diagram of a prototype device;

figure 2 - timing diagrams of the device prototype;

figure 3 is a block diagram of the proposed pulse shaper;

figure 4 - graphs of the amplitude and area of the sensor signals from the rotor speed (area with u _on (1) = 0.5A _min );

5 is a timing diagram of the proposed pulse shaper;

6 is a timing chart explaining the effect of the deviation ΔS of the signal area on the value of the pulse generation threshold u _then (10).

The composition of the proposed pulse shaper from the signals of the induction speed sensors includes (Fig. 3) a first threshold element 1, a first key 2, an integrator 3, consisting of an operational amplifier 3-1, a resistor 3-2, and a capacitor 3-3, an amplitude detector 4 consisting of an operational amplifier 4-1, a diode 4-2 and a capacitor 4-3, the first 5 and second 6 resistors, the second threshold element 7, the second key 8, the third resistor 9, the third threshold element 10, the And element 11 and the one-shot 12 and the input of the former is connected to the input of the integrator 3 and through p the first threshold element 1 - with the control input of the first key 2, the outputs of which are connected to the inputs of the integrator 3, connected to the terminals of the capacitor 3-3 of this integrator, the output of the integrator 3 is connected to the first input of the third threshold element 10 and the input of the amplitude detector 4, the output of which is connected to the input of the second threshold element 7, the first output of the second key 8 and through the first resistor 5 to the second input of the third threshold element 10 and the first output of the second resistor 6, the second output of which is connected to a common bus, the output is th threshold element 10 is connected to the first input of the element And 11, the second input of which is connected to the output of the second threshold element 7, the output of the one-shot 12 is connected to the control input of the second key 8, the second output of which is connected through a third resistor 9 to the common bus, the output of the element And 11 connected to the input of the one-shot 12, the output of which is connected to the output of the shaper.

The proposed pulse shaper operates as follows. The input signals, which are a sequence of bipolar sensor signals and interference signals, are input to the threshold element 1 and integrator 3 (Fig. 5).

The threshold for switching on element 1 u _on (1) has a negative value, therefore, in the absence of an input signal or its positive polarity, the output of threshold element 1 has a low voltage level, which, when supplied to the control input of key 2, opens it. The capacitor 3-3 of the integrator 3 is discharged and its output voltage is maintained at zero level.

On the storage capacitor C (4-3) of the amplitude detector 4, the voltage u ₁ (4) is stored, which is equal to the output voltage of the integrator 3 obtained by integrating the previous negative half-wave of the signal e _c1 and corresponding to its volt-second area S _1к .

When the signal e _c2 arrives at the input of the proposed device and the negative half-wave of this signal reaches the value u _on (1), element 1 is turned on, a high voltage level u ₂ (1) is set at its output, key 2 opens and the integrator 3 integrates the negative half-wave of the signal .

The voltage u ₂ (3) obtained as a result of integration is stored on the capacitor C (4-3) of the amplitude detector 4 as voltage u ₂ (4).

The threshold for switching on the element 10 u _por1 (10) is determined by the voltage at its second input coming from the output of the amplitude detector 4 through a voltage divider at resistors 5 and 6, that is, it is determined by the area of the negative half-wave of the sensor input signal and the divider divisor. When the output signal u ₂ (3) of the integrator 3 _{exceeds the} switching threshold u _por1 (10), a high voltage level u ₂ (10) appears at the output of element 10. The threshold element 10 is returned to its initial state when the integrator 3 is reset when the negative half-wave input signal of the zero level is reached. Formed by the threshold element 10, the pulse is supplied to the first input of the element And 11.

The threshold element 7 allows the passage of pulses from the output of the element 10 through the element 11 to the input of the single-shot 12 when the output voltage u (4) exceeds the amplitude detector 4 of the threshold level u _on (7), equivalent to the value of S _{pr min} .

When the conditions u ₁ (4) ≥ u _on (7) and u ₂ (3) ≥ u _por1 (10) are _fulfilled , an impulse appears at the output of element And 11, which starts the single-shot 12. The pulse u ₂ (12) formed by the single-shot 12 is supplied simultaneously the output of the proposed device and the control input of the key 8. In this case, the key 8 is closed and there is a subdischarge of the capacitor C (4-3) through the resistor 9.

The proposed pulse shaper does not respond to interference signals e _pom (Fig. 5), the area of negative half-waves of which is less than the pulse formation threshold S _por2 (10), that is, when u ₃ (3) <u _por2 (10), and also does not generate unlimited capacitance discharge currents of the capacitor C (4-3) of the amplitude detector 4 and does not reduce the threshold voltage u _por4 (10) to 0 V when the pulse _generator e _c3 arrives at the input of the pulse shaper, the area of which slightly exceeds the pulse formation threshold S _por2 .

The value of the threshold for the formation of pulses u _nop (10) in the proposed device, as in the prototype device, depending on the level of interference can be set over a wide range up to 90% or more of the area of the useful signal. However, the level of the set threshold u of _pores (10) is determined not only by the level of interference, but also by the deviation ΔS of the volt-second area of the signal half-waves studied from its nominal value S _n . Moreover, the larger this deviation, the lower should be the set threshold u _then (10).

This dependence is explained as follows. Let the volt-second area of the studied half-wave signals has a minimum S _min and maximum S _max values, while the maximum deviation of the volt-second area of these signals from its nominal value S _n is ± ΔS (Fig.6).

Then, when a signal e _c1 arrives, the negative half-wave area of which has a maximum value S _max , a threshold level S _{pore1 is generated} and in order for the required pulse to be generated upon the subsequent arrival of a negative half-wave of signal e _c2 having a minimum area S _min , it is necessary to fulfill the condition S _por1 <S _min . But since S _min = S _n -ΔS, we get: S _nop1 <S _n -ΔS. Considering that the threshold for the formation of pulses S _{pores is} equivalent to the threshold u _pores (10), it follows from the last dependence that the larger ΔS, the less

u _then (10).

The deviation ΔS of the volt-second area of the signal half-waves studied from its nominal value S _n depends on the inaccuracy of the gap between the signal pathogens and the induction speed sensor, on the spread of the geometric and magnetic parameters of the pathogens and for the number of pathogens Z≥2 it can be significant.

Therefore, the proposed pulse shaper is rational to use in systems having a precision setting Z≥2 of signal pathogens or having only one such pathogen. In the latter case, there are no strict requirements for the installation of the pathogen and its parameters.

The proposed pulse shaper consists of functional blocks that are widely covered in the technical literature. So, for example, a description of the principle of operation and calculation of the main elements of the integrator are given in [5, p. 127]. On the block diagrams of figure 1 and figure 3 shows one of the simplest versions of the implementation of the amplitude detector 4. If necessary, it is possible to use a high-quality amplitude detector, for example, given in [5, p.234].

The integrator 3 and amplitude detector 4 can be performed on operational amplifiers, for example, on a 140UD20 chip, threshold elements 1, 7, and 10 on comparators, for example, 597CA3 [6], keys 2 and 8, on analog keys, for example, 590KN9 δKO .347.000TU10, and the single-shot 12 on the 564AG1 δKO.347.064TU32 chip.

The proposed pulse shaper is relatively simple to implement and provides high reliability and noise immunity when operating in conditions of a limited deviation of the volt-second area of the studied half-wave signals from its nominal value.

Together with a frequency measuring device [7], this shaper can be used primarily in noise-resistant high-precision speed measurement modules that are part of emergency protection systems for energy-saturated objects, such as, for example, liquid-propellant rocket and aircraft gas turbine engines [8].

The application of the proposed pulse shaper will increase the effectiveness of emergency protection systems of the studied objects and test benches, improve the quality of mining facilities, reduce its time.

LITERATURE

1. USSR copyright certificate No. 1550611 A1, H03K 5/24, G05B 1/01, publ. March 15, 1990

2. Patent RU No. 2173022 C2, IPC7 H03K 5/153, publ. August 27, 2001

3. Sensors of thermophysical and mechanical parameters. Directory. / Under the general editorship of Yu.N. Koptev. Volume 2, M., Publishing enterprise of the journal "Radio Engineering", 2000, p. 561, 616-618.

4. OG 018 rotational speed converter. Technical conditions W2.780.018TU.

5. L. Falkenberry. The use of operational amplifiers and linear ICs. Perev. from English M: Mir, 1985

6. Integrated circuits. Operational amplifiers and comparators. Handbook, Volume 12, ed. 2, Dodeca-21c, 2002

7. Patent RU N2300112 C2, IPC G01R 23/10, publ. 05/27/2007.

8. NN Sevryugin, I. A. Potapov, A. N. Popov, A. M. Tsirikhov “Experience in the automation of the testing process of aircraft gas turbine engines. || Devices and Systems. Management, control, diagnostics. 2001. N 5.

Claims (1)

A pulse generator from signals of induction speed sensors, comprising an integrator, an amplitude detector, three threshold elements, two keys, an I element, a single vibrator and two resistors, the input of the driver being connected to the integrator input and through the first threshold element to the control input of the first key, outputs which are connected to the integrator inputs connected to the integrator capacitor terminals, the integrator output is connected to the first input of the third threshold element and the amplitude detector input, the output of which the second is connected to the input of the second threshold element, the first output of the second key and through the first resistor to the second input of the third threshold element and the first output of the second resistor, the second output of which is connected to a common bus, the output of the third threshold element is connected to the first input of the element And, the second input which is connected to the output of the second threshold element, the output of the one-shot is connected to the control input of the second key, characterized in that a third resistor is inserted into it, and the second output of the second key is connected via t ety resistor to the common bus, and the output element is connected to the input monostable multivibrator, whose output is connected to the output driver, the switching threshold of the first threshold element is set to 30-50% of the minimum amplitude of the test signal of half the speed of induction sensors.

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