SU678666A1 - Phase shift-to-time interval converter - Google Patents

Description

The proposed device relates to electrical measuring equipment and can be applied when measuring phase shifts. A phase shifter into a code is known, in which the time interval is filled with auxiliary pulses, k, counting their quantities in 1. Such a transmitter can only be used at fixed frequencies. A converter is known in which the compensation of the frequency deviation occurs at the level of phase conversion time interval 2. However, this preoolator requires a source of stable voltage, has a low accuracy of pre-phase error from the variation of the automatic voltage and low speed of the converter inertia frequency voltage. Of the known devices, the closest in technical essence to the invention is a converter consisting of two short pulse formers corresponding to the zero voltage of the input voltages, and a trigger, whose inputs are connected to the outputs of the formers, and the output of the trigger from the second input of which is connected to the output of the generator h. A disadvantage of this device is the e-pc dependence of the time interval received at the output of the trigger on the frequency of the input voltages. In this case, the output code is proportional not only to the phase shift, but also to the frequency of input voltages. This limits the scope of application of the device. The purpose of the invention is the expansion of the clock range and improved conversion accuracy. The goal is achieved by the fact that in the proposed

A reference shift in the time interval and an additional input voltage source, two integrators, three keys, an inverter, a zero detector and a trigger. The output of the reference voltage source is connected to the potential inputs of the first and second keys, the control inputs of which are connected respectively to the output of the first trigger and the direct output of the second trigger, the inverse output of which is connected to the first inputs of the third key and the additional trigger. The output of the first key through the first integrator and the zero detector is connected to the second input of the additional trigger, the output of the second key through the second integrator and the inverter to the second input of the third key, the output of which is connected to the input of the first integrator.

FIG. 1 shows a functional diagram of a phase shift converter in a time interval} in FIG. 2 - plots of voltages at corresponding points

devices.

The converter contains drivers 1 and 2, the outputs of which are connected to the inputs of the first trigger 3, and the output of the driver 2 is connected to the input of the counting trigger 4. The output of the trigger 3 and the first output of trigger 4 are respectively connected to the control inputs of the keys 5 and 6, to the inputs of which are supplied the reference voltage U of the reference voltage source 7. The second output of the trigger 4 is connected to the control input of the switch 8, and the output of the latter to the output of the switch 5 and the input of the first integrator 9. The output of the switch 6 is connected to the input of the second integrator 10, the output to orogo through an inverter 11 connected to the input key 8. The output of the integrator 9 via the zero detector 12 is connected to a first input of the third flip-flop 13, and the second input of the latter - a second output flip-flop 4.

In the initial state, the voltage U is fed to the input of the imager 1, and the voltage and 2 is supplied to the input of the imager 2. relative to which the voltage phase U is measured. At the moment of voltage transition (J and Ug through a zero level from a negative to a positive value, short impulses are formed at the outputs of the formers 1 and 2, which, arriving at the inputs of the trigger 3, form) T at its output time interval t, 1)) o ; 1or11I1: the phase phase shift

V 21G i / T,

and Og, where T is the oscillation period

u -t

Impulse

opens the key 5 and 1P tegrato) Oh

Gp

and

from the reference source

op

before stress

and Fri - op tde; - constant of integrator time 9. Simultaneously at the first output of trnx

 4 an impulse d is formed; with the help of T, which opens the key 6, and the integrator 10 is charged from T () the same source of the reference voltage Uon -o IF-

T

 mg-op

1 2 constant time integrator 10.

Upon the passage of the next pulse from the imaging unit 2, the trigger 4 is reset, the key 6 is closed, and the key 8 is opened.

The voltage from the output of the integrator U is inverted by the inverter 11 and fed through the switch 8 to the input of the input grader 9, which stores the voltage U, - ,; and starts discharging it. At the same time, the signal from the second trigger 4 flips trigger 13, forming the beginning of the output time interval t.

The integrator 9 is discharged ao zero during fc x.

from where

Because

get -t cn, 211

where K is the proportionality coefficient.

When os: the zero level at the output of the integrator 9, the detector zero zero flips the trigger 13, forming a time interval t- at its output.

Claims (3)

Thus, the value of t does not depend on the duration of the period of the input and voltage, between which the phase shift is measured. B.; i.iMiu3N (the device is not 11rp pooled (.: Cc. To stability of the reference program, 1 as it does not enter into the course); the expression for tj (, noscht device from the current phase shift isopropy .) input voltages in the time interval (. Claim In addition, with a counting input of the second trigger, characterized in that, in order to expand the frequency range and increase the accuracy of the conversion, a reference voltage source, two integrators, three switches, an inverter, a zero detector and a trigger are added to it, and the output the reference voltage source is connected to the potential inputs of the first and second keys, the control inputs of which are connected respectively to the output of the first triger and to the direct output of the second trigger, the inverse output of which is connected to the first inputs of the third key and additional trigger, the output of the first key through the first integrator, and the zero detector connected to the second input of the additional trigger, the output of the second key through the second integrator and the inverter to the second input of the third key, the output of which is connected to the input of the first integrator. Sources of information taken into account in the examination 1. Ermolov R, S. and others. Digital measuring devices. L., Energie, 1971. 2. Bulletin of the Kiev Polytechnic Institute, series Automatics and electrical equipment, No. 11, 1974. 3. The peaceful fl. T. Digital phase meters ry. L ,, Energie, 1974.