SU1117834A1 - Frequency-to-voltage converter - Google Patents

Abstract

A FREQUENCY CONVERTER IN THE NAPR SCENIB, containing a pulse shaper, serially connected output integrator and integrator with the unit for setting the initial conditions. the output of which is connected to the input of the fixing unit, the output of which is connected to the first input of the adder, the second input of which is connected to the source of the reference voltage — the first output of the forkshrevatel pulses connected to the control input of the fixing unit, and the second output of the pulse builder is connected to the control the input of the integrator with the installation of the initial conditions, characterized in that, in order to improve speed in a wide range of convertible Frequencies, a key, a comparator and additional inte A rator with an initial conditions setting unit, the output of a VV of which is connected to the first input of a comms parator, and the input is connected to a source of a reference voltage, the key input is connected to the output of an adder, the output of a key is connected to the input of an output integrator, Vira, Control (i the key input is connected to the output of the comparator, the second input of which is connected to the output of the output integrator, and the control input of the additional integrator with the installation unit from the initial conditions is connected to the second 4 output of the pulse former.

Description

1 The invention relates to information and measuring technology and can be used in systems of automatic control and regulation. Frequency-to-voltage devices are known that use linear circuits with frequency dependent properties. F} The disadvantages of these devices are low accuracy and speed due to the output signal being dependent on the input signal and the need to filter the output signal. The closest to the technical essence of the invention is a device for converting a pulse tracking frequency to a DC voltage, comprising a Pimpulse driver, an output integrator and an integrator with an installation unit of the initial conditions of the fixing unit, an adder, a source of reference voltage, and an integrator with the installation unit initial conditions are connected through fixing unit, the adder and the unit with the output integrator, the output of which is connected to the input of the integrator, with the unit setting the initial conditions, The reference voltage source is connected to one of the inputs of the summator. The converter is built as a closed pulse system, supporting a voltage close to zero at the output of the clamping device, due to the presence of the output integrating amplifier 2. A disadvantage of the known device is that a high speed is achieved in a narrow range of measured frequencies. The purpose of the invention is to increase speed in a wide range of convertible frequencies. The goal is achieved by the fact that a frequency converter into a voltage containing a pulse shaper, serially connected output integrator and integrator with an initial condition setting node, the output of which is connected to the input of the fixing unit &, whose output is connected to the first input of the adder, whose input is connected to the source of the reference voltage, the first output of the pulse former to the control input of the fixing unit, and the second output of the pulse generator 34 to the control input of the integrator and a key, a comparator, and an additional integrator with a node for the initial conditions, whose output is connected to the first input of the comparator, are entered with the initial conditions setting node, and the input is connected to the source of this voltage, the key input is connected to the output of the adder output integrator, the control key input — with the output of the aTopa company, the second input of which is connected to the output of the output integrator, and the control input of the additional integrator with the initial conditions setting unit is connected to the second output of the driver Pulses. . Figure 1 shows the functional diagram of the device; Figure 2 is an electrical diagram of the device; nafig.Z - time diagrams of his work. The frequency converter in the voltage contains the pulse shaper 1, serially connected output integrated grid 2 and integrator 3 with the initial conditions setting node, the outputs of which are connected to the input of fixer 4, the output of which is connected to the first input of the adder 5, the second input of which is connected to the source 6 of the reference voltage, the first output of the pulse shaper to the control input of the fixing unit 4, and the second output of the pulse shaper - to the control input of the integrator 3 with the installation node the key, 7, the comparator 8 and the additional integrator 9 with the initial conditions setting node, the output of which is connected to the first input of the comparator 8, and the input to the source 6 of the reference voltage, the key input with the output of the adder 5, the output key of the output of the output Integrator 2, the control input of the key is with the output of the comparator 8, the second input of which is connected to the output of the output integrator 2, and the control input of the additional integrator 9 with the initial conditions setting unit is connected to the second output of the pulse former 1. The device works as follows. With the arrival of the next pulsed signal of the converted frequency U (Fig. 3), the first output of the driver 1 generates a pulse signal 0 (in Fig. 3) arriving at the control input of the fixing unit 4, and the value of the output voltage Uj is memorized (Fig. 3) of the integrator 3 reached at the previous device operation cycle. At the end of the pulse (} the fixing unit goes into storage mode, and the voltage at its output U (Fig. 3) remains unchanged until the passage of the following pulse signal H. At the same time, at the end of the pulse and at the second output of the driver, a pulse signal U is formed ( (3), arriving at the control inputs of the installation nodes of the initial conditions of the integrators 3 and 9, and the output voltage of the integrator Uj and Ug is zeroed (Fig. 3) .The output voltage of the integrator 9 decreases to the value of the output voltage of the integrator 2 (Fig .G) and at the output of the comparator 8 is formed: the leading edge of the pulse signal Ug (Fig. 3), fed to the control input of the key 7. The key 7 is turned on, and the voltage from the output of the adder 5, is equal to the sum of the reference voltage UQ of the source 6 and the output voltage the fixed unit U (Fig. 3), is fed to the input of the integrator 2. The output voltage Ug ,,, the integrator 2 (Fig. 3), which is the output signal of the entire device, begins to change depending on the size and polarity of the output the voltage of the adder 5. At the end of the pulse integrators 3 and 9 p Transition to the voltage integration mode (and their output voltages U and Ug (Fig. 3) increase. When the output voltage of the integrator 9 reaches a value equal to the voltage U g, the leading edge of the pulse signal Od (Fig. 3) is formed at the output of the comparator B, the key 7 is turned off, and the integrator 2 switches to the storage mode until it arrives. pulse signal Ug. With the npH stroke of the next pulse, the order of operations is repeated. The integrator 2, covered by the feedback, in the circuit of which integrator 3 and fixing unit 4 are included, is an astatic amplifier. Therefore, in a steady state at a constant frequency of the input signal, the output voltage of the adder 5 is equal to zero, i.e. the steady-state value U4 (U) is equal in V U4y in the opposite way to the reference voltage and the reference voltage U {j: U | .p -Ujj At the same time, the value (J. the value of the sawtooth output voltage of the integrator 3 at the time of arrival of the next input pulse signals, directly proportional to the period of the converted frequency T and the steady-state value of the output voltage of the device, and OUTPUT Vrx.YCT) is the time of the integrator 3. Thus. -UdT.f where is the frequency of the input signal. Therefore, the steady-state value of the output voltage of the device is directly proportional to the frequency of the input pulse signals. On fig.Z steady-state mode of operation of the device correspond to the first and third cycle of operation of the device. The steady-state value of the output voltage of the device does not depend on the duration t of the pulse signal Oa (Fig. 3) received on the control input of the switch 7. However, to ensure the stability and high speed of the device in a wide range of the frequency to be converted, the duration of conductive is equal to tr The state of the key 7 on each device operation cycle changed in direct proportion to the output voltage Ug. For the proposed device, this condition is ensured. Indeed, the duration of the pulse signal Ug is equal to the rise interval of the output voltage of the integrator 9 from a zero value for a value equal to the output voltage of the device i.v, u ,,, is the time constant of the integrator 9. Therefore, K out / H,); those. directly proportional to the value of the output voltage. With such a dependence, it is possible, by choosing certain ratios between the device integrators' time constants, to achieve the highest possible device performance when the frequency jump of the input pulse signal is tested, regardless of the initial frequency value. To prove the last statement, let us consider the operation of the device at two consecutive intervals of repeatability, (n) and (n + 1), assuming the beginning of each of the intervals to coincide with the output pulse of the driver 1 of the pulses U. (FIG. 3). The values of the output voltage of the device after locking the key 7 at the nth and (h + 1) -M intervals are interconnected by the relation e6 ,, (Vo-y4Cn 0), (1) where Tj is the integrator time constant 2j and is the value the voltage at the output of the 4x1 block of the block on the (n + t) -M repetition interval, equal to the voltage at the output of the integrator 3 at the time of the termination of the hth repetition interval. .TCn} u ,,, n, (2) where Tj is the time constant of the integrator of torus 3; - the duration of the h-ro interval. Substituting (2) into (t), we obtain the difference equation describing the operation of the device (-). W in the steady state T t TCn + iJs: r cohst; Youxl: eyD 8xxcr. VDPP-G |. The value of Ug is determined from (3) / 7 T,, Mct, (4) 1 where the measured value of the measured pulse frequency of the input pulses is set. The condition of stable operation of the device in accordance with (3) has the form -, - l№M The condition of the maximum speed of the device - reaching the output voltage of the device at a fixed value in one interval and repeatability - has the form) / TY. The voltage at the output of the integrator 9 during the time interval reaches the value UgyxCb-nj, Ueb., (F where T is the time constant of the integrator 9. Substituting in (7) the value of (h + lJ from (3), we get f-VWf) f .. (.. In case of equality of constant time and T- from (8) we get T P equality of integration of integrators 2 and 9, the proposed device has the maximum speed in the entire range of variation of the frequency that disappears: when the frequency of the input pulses changes from the value of {to the value of f the steady-state value of the voltage at the output of the device The proportional f2 is achieved with a delay of one pulse period. Thus, the proposed device, which provides high accuracy of frequency conversion to voltage due to astatic feedback based on the measured value, realizes the limiting speed in a wide frequency range.

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Claims (1)

A VOLTAGE FREQUENCY CONVERTER containing a pulse shaper, an output integrator and an integrator connected in series with an initial setting unit, the output of which is connected to the input of the clamping unit, the output of which is connected to the first input of the adder, the second input of which is connected to the reference voltage source, the first output the pulse shaper is connected to the control input of the fixing unit, and the second output of the pulse shaper 'is connected to the-control input of the integrator with the installation node n of the initial conditions, characterized in that, in order to improve performance in a wide range of converted Frequencies, a key, a comparator and an additional integrator with an initial setting unit are introduced into it, the output of which is connected to the first input of the comparator, and the input to the source of the reference voltage, input the key is connected to the output of the adder, the output of the key is connected to the input of the output integrator. a torus, the control input of the key is connected to the output of the comparator, the second input of which is connected to the output of the output integrator, and the control input of the additional integrator with the node for setting the initial conditions is connected to the second output of the pulse shaper.