SU1208600A1 - Frequency-to-voltage converter - Google Patents

Abstract

The invention relates to automation, remote control and measurement technology. The device contains a shaper 1 input pulses, a metering device 2, an input 3 and an output 14 bus, analog switches 4 and 10, synchronized generators 5, elements 6 and 7 1SH, distributor B, 1) triggers 9, shaper 11 pulse recording, shaper 12 trailing edge, low-pass filter 13, overload signal bus 16, and a capacitor 17. The device allows setting HeoexoAnbi ro the time of the low-pass filter 13 for a time equal to the input frequency period, which increases the speed of the device. The source voltage changes 15 opor-- Nogo voltage dependence can be formed at a constant time low-pass filter of the input frequency, that expands the functionality of the device. The device provides an indication of overload. & T. Il. f Yesh 3

Description

ten

25

I1208600

The invention relates to automation, telemechanics and measuring equipment.

The purpose of the invention is to increase the speed and expand the functionality of the device by adaptive selection of the constant time of the low-pass filter and control of its cut-off frequency using a single voltage source.

Figure 1 shows a functional diagram of the device j in figure 2 - time diagrams of its work; in FIG. 3 - the dependence of the reduced error on the pulsations depending on 5 on the frequency of the INPUT signal.

The frequency to voltage converter (Fig. 1) contains a driver

I input pulses, metering device 2, input bus 3 devices 20 analog key 4, a group of h synchronized generators 5, first

6 and second 7 P-input elements OR, distributor 8, group of and D-flip-flops 9, group of analog keys 10, driver

A write pulse II, a falling front driver 12, a low pass 13 input filter, device output bus 14, reference voltage source 15, overload signal bus 16, and a capacitor 17.

The device input bus 3 is connected via the input pulse driver 1 to the input of the metering device 2, the output of which is simultaneously connected to the input driver 1 1 of the write pulse, the control input of the analog switch 4 and the signal inputs of a group of analog switches 10. Reference voltage source 15 An analog switch 4 is connected to the ypravlyh inputs of a group of h synchronized generators 5, the outputs of which are connected to the corresponding inputs of the second and-input element 7 OR, the output of which is connected to information This C-input of the distributor 8 "R-input of the installation in O of the last 50 is connected to the output of the rear edge former 12, the input of which is connected to the output of the former of the write pulse 11 and the C-inputs of the group of D-flip-flops 9) ryh connected to the corresponding outputs of the distributor 8. Outputs and. D-triggers 9 are connected with respectively 30

35

40

45

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The input inputs of the first h input element 6 OR and the control inputs of the group of AND analog switches 10, signal & e outputs of which are connected to the corresponding resistors AND input filter 13 low frequencies, the other poles of which through its capacitor 17 are connected to the common bus device. The connection point of the resistors of the low pass filter 13 and the capacitor 17 is connected to the output bus 14 of the device. The output of the first h-input element 6 ILH connected to the bus 16 signal overload.

The device works as follows.

In FIG. 3, based on the expression

. (1) -Zti (f, -fJ

The dependences of the reduced ripple error on the frequency of the input signal f are plotted for different constant times Tj of the low-pass filter for (1,2,3, ..., and, constant duration of the metered pulse t and the frequency range of the input signal from i to {( i-j}., From FIG. 3 it follows that for f e, -E („,) the reduced error from

ripple D, e (; b and (.. when determining the accuracy of the frequency converter in the voltage takes into account the maximum value of the reduced error from the ripple at the lowest input frequency f From the described. it follows that the choice of the minimum frequency in each sub-band from fj to f (ni) it is necessary to make so that the reduced error from the pulsations does not exceed f max P of constant time ti (Fig. 3).

The choice of the number of frequency subranges and depends on the magnitude of the gain in speed P11

one

mi

m1 is the number of periods required to terminate the transition process without switching over a constant time t, with an abrupt change in frequency from o (()) t is the number of periods necessary to complete the transition process at constant | - the moment of the beginning of the first impulse in the pack formed by the generator G I in the - th period. In figure 2, U5-1 conditionally shows the second pulse generated by the first generator G, where utj is f 4. 1., (K + 1), k

- 2. s, 1 „t.

At high frequencies

nn time with the same change in the input frequency.

Depending on the specific requirements for the amplitude-frequency characteristic of the converter, the response in each frequency sub-band may be different or the same.

 the duration of the periods is less and the conditionally generated input signal c is fulfilled.

„4-4 T T i

the output of the shaper 1 input signal intervals t - Cn (v, -) fishing (figure 2, and) at the beginning of the K-th formed by a group of and synchronous (K + 1) -th, (K + 2) - first, ... periods, zazirovannyh generators 5, respectively, tlf -, ... starts the metering device periods of the input frequency device 2, which generates pulses of constant volt-second area (figure 2, Uj). For the duration of the dosing pulse in each period of 15-tn, fto tn, the analog

20

f (h-n), ---, fb, ii, during which the time constant of the low-pass filter 13 is switched (FIG. 2, Uj, period T, corresponding to the minimum input frequency

.,)

a key 4 that connects the source. The output pulses of a group of and 15 reference voltages to the inputs of the group of synchronized generators 5 are read from the synchronized generator and the second element of the RSHI 7 is fed to the ditch 5. At the outputs of the indicated 5 informational input of the distributor 8

(Fig. 2, and) The number of these pulses, counted at the end of the period, indicates the number of the frequency subband with the corresponding constant 30 time of the low-pass filter 13 (Fig. 2, Ug :,, .-., U9. (. , Ug-,). The output and the cables of the distributor 8 are fed to the corresponding .D-inputs of a group of h D-flip-flops 9. For the duration of time t, the output pulses of the driver 11 (Fig.2, -and ;,)

the generators set the zero voltage level (Fig. 2, Us-i j --- U5- (n - i; US-H) of the end points of the dosage:

, K + 2. to

pulses to, each of the synchronized G generators

(h-1):

GH groups FROM h synchronized generators 5 forms bursts of pulses, which are delayed in the Kth period Tj. respectively for the time., .., 35

4vt-i)

- +

,to

 L VI

-t,

back-ground C-inputs of a group of AND D-flip-flops 9 recording information

zhanny in the (h + 1) -th period)

at the time ..., C.Y-tr); etc., which is determined by the voltage of the source 15 of the reference voltage in each period. In this case, a single pulse is used from a pack of pulses generated by generators C, ...,), p / o and h l, och from the group of synchronized output genes 45 (Fig. 2, Ug-c), c. + 2 ,) - m

from the outputs of the distributor 8. In the K.-M period, starting from the moment t, information is recorded from the (hl) -ro output of the distributor 8 (figure 2, Ug- (p, in (K + 1) -th period t, since t with i-th

- | - - HD .--- (Jtt f.

period starting from the moment - with (h-l) -ro output (figure 2, Ug- ()), etc.

rators 5. This mode is achieved by an appropriate choice of the duration of the pauses between the first and second pulses generated by each generator G, ..., G (H. ,,), Gn group of synchronized generators 5 at the minimum input frequency f 1 / Tk,

to

AJ-.vj. (K4-1J. To.

, t-i

(2)

, (K)

where TC

- the moment of the end of KTo of the periodJ

B | - the moment of the beginning of the first impulse in the pack formed by the generator G I in the - th period. In figure 2, U5-1 conditionally shows the second pulse generated by the first generator G, where utj is f 4. 1., (K + 1), k

- 2. s, 1 „t.

At high frequencies

intervals t - С-н (v, -) formed by a group of synchronized generators 5, correspond to periods of the input frequency

f (h-n), ---, fb, ii, during which the time constant of the low-pass filter 13 is switched (FIG. 2, Uj, period T, corresponding to the minimum input frequency

(h-1):

y ode., ..,

On the C-inputs of the group of AND D-flip-flops 9, the following information is recorded: info / o and hl, output pch (Fig. 2, Ug-c), v. + 2,) - m

/ o and hl, och output (Fig. 2, Ug-ts), V. + 2,) - m

from the outputs of the distributor 8. In the K.-M period, starting from the moment t, information is recorded from the (hl) -ro output of the distributor 8 (figure 2, Ug- (p, in (K + 1) -th period t, since t with i-th

/ o and hl, och 45 output (Fig. 2, Ug-c), century + 2,) - m

50

55

- | - - HD .--- (Jtt f.

period starting from the moment - with (h-l) -ro output (figure 2, Ug- ()), etc.

In the absence of a potential at the C inputs of the group of h triggers 9, the information recorded from the outputs of the distributor 8 is memorized (FIG. 2, Ug.T,..., Ug.v ,.),

Ua). The output pulses of a group of n D-flip-flops 9 control a group of and analog switches 10, which, depending on the number of the frequency subband, are connected with

The corresponding 13 low-pass filter resistor. In the K-th period of Ti, the (I-1) -th key is open, which sets the time constant 1 of the low-pass filter 13 (Fig. 2, Ug () in the (K. + 1) -th period T (open h-and the key that sets, (figure 2, Uj-H) j in (K + 2) -th period TlKt.) open (and-1) -th key, which sets (figure 2, Ug.) ).

The former 12 generates short pulses delayed relative to the back edges of the pulses of the former 11 for the time t. (Fig. 2, And which are used to set the distributor 8 in O, preparing it for operation in the next period

Thus, the device operates at, where f (, i) is the upper limit of the frequency of the input signal.

At 1 f (hn;, y, i.e., the period of the input frequency T.) is longer than the duration t c of the metering pulse (Fig. 2, i), at the outputs of a group of h synchronized generators 5 over a period T (, 2 ) there are no pulses, which in the next (K + 3) -th period results in closing the group of keys 10 (FIG. 2, from,

9- (h-i) j - g-h) At the output 16 of the first and-input logic element 6 OR, in the (K + 3) -th period, a zero level is set (FIGS. 2, 5).

In the case when -, i.e. the input frequency period is shorter than the duration of the dosing unit (figure 2, needle.) starting from time i :() the output pulse of the driver 1 sets the zero level at the output of the driver 2 (figure 2, (J, Uj). In this In the (K + 4) -th period, all the keys of the key group 10 are closed, since there are no pulses at the outputs of the group from C synchronized generators 5. At the output of the first element of the VGSH 6, the (K + 4) -th period is set to zero (figure 2, Ug.) Thus, with input frequencies

f (H-M) (required for rewriting information

from the distributor 8 and its setting to zero) an indication of overload in the previous period T (,) is provided over the next)

in the form of a zero level at the output of the element 6 OR and, respectively, on the bus 16. signal overload. In addition, on the output bus 14 of the device, the result corresponding to the previous period (k + g) is stored, since the group keys from and the keys 10 are closed (the recording device connected to the output bus 14 has a rather large input resistance). This result is maintained until the overload ends.

The proposed device makes it possible to establish the necessary time constant of the lowpass filter 13 over a time equal to the period of the input frequency, which increases the speed of the device as a whole. By varying the voltage of the reference source 15, the high frequencies in each frequency subband can be changed, as well as their number, which makes it possible to form the dependence of the time constant of the low pass filter on the input frequency as desired and expands the functionality of the device. The device provides an indication of overload with a significant increase in the upper limit of the frequency of the input signal, which also extends its functionality.

Claims (1)

Invention Formula .one. A frequency to voltage converter containing a serially connected input driver and a metering element, and an input driver signal input connected to the input bus of the device characterized in that, in order to improve performance and enhance functionality, an analog key group of h synchronized generators is introduced into it , the first and second h-input elements SH, distributor, a group of And D-flip-flops, a group of and analog keys, write pulse shaper, driver back its front, the source of the reference voltage and h-input low-pass filter, the output of which is connected to the output bus of the device, the output of the metering element is connected to the input of the recording pulse shaper, the signal inputs of a group of analog keys and the control input of the analog key through which the source the reference voltage is connected to the inputs of a group of synchronized generators whose outputs are connected to the corresponding inputs of the second AND input element OR whose output is connected to the information input m distributor set input of G is connected to the output of the trailing edge shaper having an input connected to the output pulse shaper recording and h of group C -BXOdami and T) flip-flops, n D-input of which is connected to the respective distributor, the outputs l, h the outputs of the P-triggers are connected to the corresponding inputs of the first h input element OR and the control inputs of a group of h analog keys, the h signal outputs of which are connected to the corresponding inputs of the h-input lowpass filter and the output of the first I input element OR connected to the bus signal overload device. 2, the Converter according to claim 1, about t The h-input low-pass filter contains h resistors and a capacitor, and the first terminals of the resistors are the inputs of the h-input low-pass filter, the output of which is connected to the second one of the resistors and through a capacitor to the common bus of the device. fig 2 fn I tw cortst 7 t;, & ta + -)  b / t Sn. MWC s s // j / i 7 / .J j ..