SU627586A1 - Voltage-to-frequency converter - Google Patents

Description

one

The invention relates to a pulse technique and electrical measurements, can be used in current meters voltmeters.

A voltage to frequency converter is known, comprising an integrator and switches ij. Its disadvantage is low conversion accuracy.

Closest to the proposed voltage-to-frequency converter, comprising an integrator, the output of which is connected to the input of the comparator unit, the other input of which is connected via an electronic switch to the source of the threshold voltages; the output of the comparison unit is connected to the control input of the electronic switch, and one of the inputs of the integrator is connected via an electronic switch to the source of the exemplary voltages 2.

The dependence of the output frequency., Such a converter on the input voltage U is determined by the expression:, .2 ..2, о х

 ABOUT

where UQ is the magnitude of the model voltage;

Up is the threshold voltage value;

V is the integrator time constant.

The disadvantage of this converter is the low conversion accuracy due to the instability of the integrator constant time and threshold voltage.

0

The purpose of the invention is to increase the points. transformations.

Claims (2)

The goal is achieved due to the fact that a voltage to frequency converter containing an integrator, one of whose inputs is connected to the input bus, the other input is connected via an electronic switch to the reference voltage source, and a period selector is entered through the electronic switch to the input of the reference unit. , a trigger with a counting input and an exemplary frequency generator, the output of the comparator unit is connected to the control input of the period selector, the signal input of which is connected to the output of the exemplary frequency generator, od period selector coupled to a control input of the integrator itself, and | with the control input of the electronic switches through a trigger with a counting input. FIG. 1 shows a structural electrical circuit of the device; in fig. 2 - diagrams, operation of the device. One of the inputs of the integrator 1 is connected to the input bus, the other through the electronic switch 2 to the source 3 of the reference voltage, the output to the input of the comparison unit 4, the output of which is connected to the control input of the perirda selector 5, the signal input of which is connected to the output of the generator 6 exemplary frequency. The output of the period selector 5 is connected to the control input of the integrator 1 directly, and to the control input of the electronic switch 2 via a trigger 7 with a counting input. The diagrams in FIG. 2: a - input voltage U-x (t) i b - pulses at the output of the period selector; c - voltage at the input of the reference unit; d - voltage at the second input of the integrator. The converter works as follows. Suppose that a positive voltage is applied to its input (J (-t), At time t, the voltage at the output of integrator 1 reaches zero, which triggers the comparison block 4. As a result, the control input of the integrator receives a pulse with a leading edge which integrator changes the direction of integration. During the time to, the voltage at the output of the integrator decreases linearly with the speed Uo-U, the sample voltage, with / UQ / Uyi; the integrator time constant. At the end of the time interval to ) behind The front end of the pulse from selector 5 triggers trigger 7, which via electronic switch 2 connects a positive sample voltage to the second input of the integrator. As a result, the output voltage of the integrator increases linearly with speed. triggers block 4 comparisons, and the period selector issues a regular impulse n to the control input of integrator 1, and the latter reverses the integration direction as a result of this signal. As a result, the output voltage will be e on the integrator linearly decreases with the speed N.Uh. At the end of the time interval o (at time t) the rear pulse from the selector 5 moves the trigger 7, and the electronic switch 2 connects the negative reference voltage to the second move of the integrator the output of the integrator increases linearly with the speed at the moment of time tj reaches well, which causes the operation of the comparison unit and the next change in the direction of integration. Further, the operation is repeated. The operation of the converter is described by a system of equations: and, and, and, -and, (T, -t) .. Ur-lU.t - T2-t.) Tr. Solving this system is relative and we have: 711 + 7g i f Uoto iUoto and -and, Uo-U The output frequency f of the transform is expressed as the reciprocal of umg-ie T and and | -i. f T.-tT g From the last formula it is clear that the frequency f, directly proportional to the square of the voltage 0) and depends only on UQ and tg, the errors from the instability of which can be made very small. This device compared with the known provides higher accuracy conversion. Claims of the Inverter Voltage to Frequency Converter containing an integrator, one of the inputs of which is connected to the input or not, another input through an electronic switch to the source of the reference voltage, and the integrator output to the input of the comparator unit , a period selector, a trigger with counting into soda and an exemplary frequency generator (the output of the comparator unit are connected to the control input of the period selector, the signal input of which is connected to the output of the generator At an exemplary frequency, the output of the period selector is connected to the integrator's control input directly, and to the electronic switch's control input through a trigger with a counting input. Sources of information taken into account in the examination: 1. USSR author's certificate number 367389, cl. Q01 R 19/26, 1973, 2. Authors certificate USSR 323789, class, G 01 R 19/26, 1972, RP