RU2565472C1 - Frequency-voltage converter - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: converter includes bipolar signal generator with duty ratio of two, generator of short strobe pulses 2 and 3, inverter 4, the first 5 and second 6 controlled integrators, and output generator 7 is made of the first 8 and second 9 summators, NOT logic circuit 10, divider 11 and reference voltage source 12. At that the following periodic signals of various shape may be supplied to the converter input: harmonic, bipolar rectangular, triangle and trapezoidal signals.

EFFECT: converting periodic signals of various shape.

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Description

The invention relates to a pulse technique and can be used in automatic control systems, in measuring devices, in controlled phase shifters, as well as in the construction of multiphase generators.

A device [1] is known, comprising an input pulse shaper, a metering device, input and output buses, analog keys, synchronized generators, two OR logic elements, a distributor, D-triggers, a write pulse shaper, a trailing edge shaper, a low-pass filter, overload signal bus and capacitor. The device allows to obtain an output signal proportional to the frequency of the input source, has high speed, but is quite complicated.

A device [2] is known that contains the first and second comparators, the first and second single vibrators, a controlled integrator, a sampling-storage device and a constant voltage source, the positive terminal of which is connected to a common bus, and the negative terminal is connected to the first input of the controlled integrator, to the output of which the first input of the sampling-storage device is connected, the input of which is connected to the output of the device, the input bus of which is connected to the non-inverting input of the first comparator, between the output of which and the second input of the controlled comp The first one-shot is turned on, while the inverting input of the second comparator is connected to the input bus, between the output of which and the second input of the sampling-storage device, the second one-shot is turned on, the inverting input of the first and non-inverting inputs of the second comparators are connected to the common bus.

The device allows you to get the output signal proportional to the frequency of the input source, but when working with input signals of low and infralow frequencies, an error appears in the formation of the output signal. Indeed, at low frequencies of the input signal, the time between the supply of the strobe pulses from the output of the second one-shot to the second input of the sampling-storage device is significantly increased. Therefore, during the time between two adjacent strobe pulses, the real storage capacitor of the sampling-storage device, that is, a lossy capacitor, can be significantly discharged, which will inevitably lead to an additional error of the device.

The closest device to the claimed invention in terms of essential features is the signal frequency doubler [3] adopted for the prototype, comprising a bipolar pulse shaper, first and second short pulse shapers, an inverter, first and second controlled integrators, each of which is made of an integrating amplifier and the key, the comparison circuit and the output driver, while the first and second inputs of the comparison circuit are connected to the outputs, respectively, of the first and second controlled integrators, an inverter is connected between the output of the bipolar signal shaper and the first input of the first controlled integrator, the second input of which is connected to the output of the first short pulse shaper, the input of which is connected to the input of the bipolar pulse shaper and the input of the second short pulse shaper, the second input of the second controlled integrator is connected to its output, the first input of which is connected to the output of the bipolar pulse shaper, and the first input of the output form is connected to the output of the comparison circuit ovatelya, whose output is connected to the output signal frequency doubler having an input coupled to the input of the bipolar pulses and a second input of the output driver.

When a rectangular signal, that is, video pulses with an amplitude value that varies widely, is fed to the device input, rectangular signals are generated at the device output with a frequency equal to twice the frequency of the input signal.

The problem to which the invention is directed, is to expand the functionality of the device by obtaining at its output a voltage proportional to the frequency of the input signals of various shapes.

The technical result achieved by the implementation of the invention is to expand the functionality by obtaining at its output a voltage proportional to the frequency of the input signal.

The specified technical result during the implementation of the invention is achieved by the fact that in the frequency-to-voltage converter containing the bipolar pulse shaper, the first and second short pulse shapers, the inverter, the first and second controlled integrators, the output shaper is made of the first and second adders, the logic circuit “NOT” , a divider and a reference voltage source, the negative terminal of which is connected to the common bus, and the positive terminal is the first input of the divider, the output of which is connected to the output of the output form a generator whose output is connected to the output bus of the frequency – frequency converter, the input of which is connected to the input of a bipolar pulse former, between the output of which and the first input of the first controlled integrator an inverter is connected, and the first input of the second controlled integrator is connected to the output of the bipolar pulse former the first input of the output driver is connected to the first inputs of the first and second adders, the second inputs of which are connected to the second input of the output driver, The second “NOT” circuit is connected between the output of the first adder and the third input of the second adder, the output of which is connected to the second input of the divider, the first short pulse shaper connected between the input bus frequency-voltage converter and the second input of the first controlled integrator, the second short pulse shaper connected between the input bus frequency-voltage converter and the second input of the second controlled integrator, and the first and second inputs of the output driver are connected to the outputs, respectively tween a first and a second controllable integrators.

The analysis of the prior art by the applicant, including a search by patent and scientific and technical sources of information, allowed to establish that the applicant did not find an analogue characterized by features identical to all the essential features of the claimed invention. Therefore, the claimed invention meets the condition of "novelty."

The execution of the output shaper from two adders, the logic circuit “NOT”, the divider and the source of the reference voltage, as well as the organization of new connections between the functional elements made it possible to expand the functionality of the device and to obtain a voltage proportional to the frequency of the input signal at its output.

The invention is illustrated by a block diagram of a frequency-voltage converter depicted in FIG. 1, and graphs explaining the principle of operation of the frequency-voltage converter — in FIG. 2 and FIG. 3.

The frequency-to-voltage converter contains a bipolar pulse shaper 1, first 2 and second 3 short pulse shapers, an inverter 4, first 5 and second 6 controlled integrators and an output shaper 7, which is made of the first 8 and second adders, the logic circuitry “10”, the divider 11 and the reference voltage source 12, the negative terminal of which is connected to the common bus, and the positive one is the first input of the divider 11, the output of which is connected to the output of the output driver 7, the output of which is connected to the output bus For frequency, there is voltage, the input bus of which is connected to the input of the bipolar pulse generator 1, between the output of which and the first input of the first controlled integrator 5, the inverter 4 is turned on, and the first input of the second controlled integrator 6 is connected to the output of the bipolar pulse generator 1, while the first input of the output the shaper 7 is connected to the first inputs of the first 8 and second 9 adders, the second inputs of which are connected to the second input of the output shaper 7, the logic circuit “NOT” 10 is connected between the output of the first sum ora 8 and the third input of the second adder 9, the output of which is connected to the second input of the divider 11, and the first short pulse shaper 2 is connected between the input bus frequency-voltage converter and the second input of the first controlled integrator 5, the second short pulse shaper 3 is connected between the input bus converter frequency voltage and the second input of the second controlled integrator 6, and the first and second inputs of the output driver 7 are connected to the outputs, respectively, of the first 5 and second 6 controlled in egratorov.

The frequency converter - voltage operates as follows.

Periodic signals of various shapes (harmonic, bipolar, rectangular, triangular and trapezoidal) can be fed to the input of the converter. The main requirement for such signals is the equality of the durations during the first and second half-periods, so that the square-wave signal at the output of the bipolar pulse generator 1 has a duty cycle equal to two.

When applying, for example, a harmonic signal S (t) = Asin (ωt) to the input bus with an amplitude value A and a frequency ω = 2πf (Fig. 2a), a sequence of bipolar rectangular waves is generated (Fig. 2b) pulses V ₁ (t) with an amplitude value of V _m1 .

Single vibrators 2 and 3, triggered, respectively, on the leading and trailing edges of the signal V ₁ (t), form the corresponding narrow strobe pulses D ₁ (Fig. 2, c) and D ₂ (Fig. 2, d).

The signal V ₁ (t) is supplied to the first input of the second controlled integrator 6, and the inverted signal V ₂ (t) = - V ₁ (t) is supplied to the first input of the first controlled integrator 5. Since the modulus of the inverter transfer coefficient is equal to unity, the amplitude value V _m2 (Fig. 2d) of the signal V ₂ (t) will be equal to the amplitude value V _{m1 of the} signal V ₁ (t).

The controlled integrators 5 and 6 are inverting, therefore their output signals L ₁ (t) and L ₂ (t) will be shifted by 180 electrical degrees relative to the input ones.

Upon receipt of the bipolar signals V ₁ (t) and V ₂ (t) at the first inputs of the controlled integrators 5 and 6, linearly changing signals L ₁ (t) begin to form at their outputs (Fig. 2, e and Fig. 2, g) and L ₂ (t), the maximum (amplitude) values of which L _m1 and L _m2 will depend on the amplitude values V _m1 and V _{m2 of the} corresponding signals and the time constants τ ₁ and τ _{2 of the} corresponding controlled integrators 5 and 6.

The strobe pulses D ₁ and D ₂ supplied to the second inputs of the controlled integrators 5 and 6 reset them, that is, they “bind” the corresponding signals L ₁ (t) and L ₂ (t) to the zero level, which eliminates bias (“creep” ») Of these signals due to the presence of various destabilizing factors and, above all, due to the zero-level drift of the integrators themselves.

When the converter is started during the first half-cycle (when the value of the current angle x = ωt changes in the range from 0 to π), the signal L ₂ (t) changes in the positive direction (Fig. 2, g). Then, when the gate pulse D ₂ arrives at the second input of the controlled integrator 6, the signal L ₂ (t) is reset to zero. Further, the polarity of the generated signal remains negative (Fig. 2, g).

Find the maximum value of L _m1 (Fig. 2, e) of the signal L ₁ (t) using the expression

where T ₀ = 1 / f is the period of the input signal S (t).

By analogy, we calculate the maximum value L _{m2 of the} signal L ₂ (t)

When V _m1 = V _m2 = V _m and the equality of the time constants τ ₁ = τ ₂ = τ, the maximum values of the signals L ₁ (t) and L ₂ (t) will be equal

The voltage E _F proportional to the frequency f of the input signal S (t) is formed as follows.

As a result of summing the signals L ₁ (t) and L ₂ (t) at the output of the inverting adder 8, a signal is generated (Fig. 3, c)

where k ₁₁ and k ₁₂ are the transfer coefficients of the adder 8, respectively, at the first and second inputs.

If the transmission coefficients are equal, k ₁₁ = k _{] 2} = α and the amplitude values L _m1 = L _m2 = L _{m of} linearly varying signals L ₁ (t) and L ₂ (t) are equal, the output signal M ₁ (t) will have ( Fig. 3, c) a zero value on the interval x∈ [0; π], that is, the information component in this section (within the first half-period) will be absent E _T1 = 0.

For all other sections, the value of constant voltage

that is, the voltage E _T1 generated at the output of the adder 8 will be proportional to the period T _{0 of the} input signal S (t).

Since the frequency f is inversely proportional to the period T ₀ , the voltage E _F proportional to the frequency can be found using the formula

It is possible to realize (6) using the divider 11, applying a signal to its first input directly from the output of the first adder 8, and to the second input, the reference voltage E _OP , the value of which in a particular case can be equal to unity E _OP = 1.

However, the implementation of algorithm (6) causes certain difficulties, since when starting the frequency-voltage converter (first half-period), the voltage E _T1 is zero and therefore the generated voltage E _F will theoretically tend to infinity.

To reduce the emission of voltage E _F during start-up, an additional limiter can be activated at the output of the frequency-voltage converter or the emission can be limited at the supply voltage level. In some cases, such solutions cannot be considered optimal, therefore, in the present invention, the task of reducing the initial voltage surge E _F is solved as follows.

While the signal E _T1 will be zero (the first half-cycle), it is necessary to form (Fig. 3d) a single pulse N (t) of duration τ _and = T _0/2 of a certain amplitude N _m in order to carry out the division operation E _f = E _OD / E _T.

This operation is performed using the logic circuit “NOT” 10. When a signal N (t) is input to the input of the logic circuit “NOT” 10, a single pulse N (t) of positive polarity will be generated at its output (Fig. 3d). to the third (inverting) input of the adder 9.

As a result of the summation of the signals L ₁ (t), L ₂ (t) and N (t) at the output of the adder 9, a signal is generated (Fig. 3, d)

where k ₂₁ , k ₂₂ and k ₂₃ are the transfer coefficients of the adder 9 at the corresponding inputs.

It should be noted that the signal N (t) will act only during the first half-cycle and will not participate in the further formation of the signal M ₂ (x), therefore, expression (7) can be written in the following form:

If the transmission coefficients are equal, k ₂₁ = k ₂₂ = β, the information component E _{T2 of the} signal M ₂ (x) will be equal to

With the joint solution of (6) and (9), we obtain

whence it follows that the voltage E _F will vary in proportion to the frequency f of the input signal S (t).

The present invention can be used in automatic control systems, in measuring devices, in controlled phase shifters, as well as in the construction of multiphase generators.

The converter can work with periodic signals of various shapes and can be performed in an integral design, which is the advantage of the invention.

Information sources

1. A. p. USSR No. 1208600, Н03К 7/06. Modla R.N., Pogribnoy V.A. Frequency to voltage converter 07/12/1984, publ. 01/30/1986. Bull. Number 4.

2. RF patent No. 2520409, H03K 7/06. Dubrovin B.C., Zyuzin A.M. Periodic to frequency and period converter, claim 09/25/2012, publ. 06/27/2014. Bull. Number 18.

3. A. p. USSR No. 828366, Н03В 19/06. Zakletskaya J.Ya. Signal frequency doubler 07/18/1979, publ. 05/07/1981. Bull. No. 17 (prototype).

Claims (1)

Frequency converter - voltage containing a bipolar pulse shaper, first and second short-pulse shapers, an inverter, first and second controlled integrators and an output shaper whose output is connected to the frequency-voltage converter output bus, to the input bus of which a bipolar pulse shaper input is connected, between whose output and the first input of the first controlled integrator includes an inverter, and the first input of the second controlled integrator is connected to the output of the shaper b polar pulses, characterized in that the output driver is made of the first and second adders, the logic circuit “NOT”, a divider and a voltage reference source, the negative terminal of which is connected to the common bus, and the positive terminal is connected to the first input of the divider, the output of which is connected to the output of the output shaper, the first input of which is connected to the first inputs of the first and second adders, the second inputs of which are connected to the second input of the output shaper, the logic circuit “NOT” is connected between the output of the first adder and the third m the input of the second adder, the output of which is connected to the second input of the divider, while the first short-pulse shaper is connected between the input bus frequency-voltage converter and the second input of the first controlled integrator, the second short-pulse shaper is connected between the input bus frequency-voltage converter and the second input of the second managed integrator, and the first and second inputs of the output driver are connected to the outputs of the first and second managed integrators, respectively.

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