RU158706U1 - DEVICE FOR FORMING AN INSTANT VOLTAGE VALUE SAMPLE - Google Patents

Abstract

A device for sampling an instantaneous voltage value containing an op-amp, the non-inverting input of which is grounded, and the inverting input is connected to the input voltage source through the first key and resistor, a storage capacitor is connected in the negative feedback circuit of the op-amp, in parallel with which the second key is connected, the analog inverter is connected to non-inverting input of the comparator, the inverting input of which is connected to the input voltage source, and the output - with the input of the installation in the zero state of the trigger, the output is of the latter is connected to the control input of the first key, and the input of the unit to the single state of the trigger, through the pulse shaper, is connected to the output of the clock pulse generator, which is connected through the logic inverter to the control input of the second key, characterized in that the buffer repeater at the op-amp is introduced into the device, moreover, its non-inverting input is connected to the output of the op-amp, and the inverting input is connected to its own output and the input of the analog inverter, the output of the buffer repeater to the op-amp serves as the output of the device.

Description

DEVICE FOR FORMING AN INSTANT VOLTAGE VALUE SAMPLE

The technical field to which the utility model relates.

The utility model relates to electrical engineering, in particular to devices for generating samples of instantaneous voltage values.

State of the art

A device for sampling and storage containing an analog key, two operational amplifiers, a storage capacitor, a feedback resistor, a limiting resistor, two on-board diodes (Zhavoronkova M.S., Bondar S.N. Development of a high-speed device for sampling and storage with increased accuracy / / Methods and technical means of increasing the efficiency of the use of electrical equipment in industry and agriculture: collection of scientific papers based on the materials of the 75th scientific and practical conference of the Electric Power Department SSAU. - Stavropol: AGRUS, 2011.S. 102, Fig. 3). A feature of this device is the fulfillment of the conditions:

where τ _p is the gating interval (sampling);

τ ₃ is the charge time of the storage capacitor.

The disadvantage of this device is the occurrence of an error in sampling the analog voltage, due to the fact that the input voltage changes during the sampling interval (sampling), which leads to an ambiguity in the determination of the output voltage (within Δ and (Fig. 1)), since it depends on the time of sampling. Moreover, the noted error is fundamentally unrecoverable due to the fulfillment of condition (1).

The closest analogue is the prototype of the claimed technical solution is a device for sampling instantaneous voltage values (patent RU 2230376, IPC G11C 27/02).

A device for sampling the instantaneous voltage value contains an operational amplifier (op-amp), the non-inverting input of which is grounded, and the inverting input is connected to the input voltage source through the first switch and resistor, and a storage capacitor is connected in the negative feedback circuit of the op-amp, in parallel with which the second switch is connected, and the output of the device is the op-amp output, which is connected through an analog inverter to the non-inverting input of the comparator, whose inverting input is connected to the input source voltage, and the output is with the input to the zero state of the trigger, the output of the latter is connected to the control input of the first key, and the input to the single state of the trigger, through a pulse shaper, is connected to the output of the clock generator, which is connected to the control input via a logic inverter second key.

Effective storage time (storage time Δt _storage during which condition (2) is satisfied

where ξ is the permissible error of measuring the voltage value) is determined by the discharge constant of the integrator τ _bit performed on the basis of

ОУ and loaded on parallel connected input resistances of the analog inverter R _in.AI and device load R _in.n

that is, the larger the τ _bit , the greater the _storage Δt for a given ξ.

Since, according to the prototype, the analog inverter can be made in the usual way based on the op-amp and two resistors (at the input and in the negative feedback circuit), its input resistance will not exceed hundreds

kOhm, MOhm units, and even without taking into account the influence of the input load resistance Δt of the _{storage, it} will be small in comparison with the known devices (Volovich GI, Yezhov VB. ADC and DAC chips. - M.: Dodeka-XXI Publishing House, 2005.P. 40, Fig. 51, 52).

The disadvantages of this device are:

- a small value of the effective storage time;

- limited functionality - the device provides a technical result only in the case of high resistance load.

Utility Model Disclosure

The technical result that can be achieved using the proposed utility model is to increase the value of the effective storage time and increase accuracy when sampling the instantaneous voltage value, regardless of the load resistance of the device.

The technical result is achieved by the fact that the device for generating an instantaneous voltage value contains an op-amp, the non-inverting input of which is grounded, and the inverting input is connected to the input voltage source through the first switch and resistor, and a storage capacitor is included in the negative feedback circuit of the op-amp, in parallel with which the second key, the analog inverter is connected to the non-inverting input of the comparator, the inverting input of which is connected to the input voltage source, and the output to the input the trigger is in the zero state, the output of the latter is connected to the control input of the first key, and the input to the single state of the trigger, through a pulse shaper, is connected to the output of the clock pulse generator, which is connected to the control input of the second key through a logic inverter, a buffer repeater at the op amp moreover, its non-inverting input is connected to the output of the op-amp, and the inverting input is connected to

own output, and the input of an analog inverter, the output of the buffer repeater on the OS is the output of the device,

Brief Description of the Drawings

In FIG. 1, 3 are timing diagrams explaining the operation of the device.

In FIG. 2, a functional diagram of a device for sampling an instantaneous voltage value is shown.

Utility Model Implementation

A device for sampling the instantaneous voltage value contains an input voltage source 1, op-amp 2, a first key 3, a resistor 4, a storage capacitor 5, a second key 6, an analog inverter 7, a comparator 8, a clock generator (GTI) 9, a logical inverter 10, pulse shaper 11, trigger 12, a buffer follower on the op-amp 13, and the non-inverting input of the op-amp 2 is grounded, and the inverting input through the first key 3 and resistor 4 is connected to the input voltage source 1, the memory circuit in the negative feedback circuit of the op-amp 2 is turned on a capacitor 5, in parallel with which the second switch 6 is connected, an analog inverter 7 is connected to the non-inverting input of the comparator 8, the inverting input of which is connected to the input voltage source 1, and the output to the trigger input of the trigger 12, the output of the latter is connected to the control input of the first key 3, and the input of the unit into the single state of the trigger 12, through the pulse shaper 11, is connected to the output of the clock generator 9, which is connected through the logical inverter 10 to the control input of the second key 6, the inverting input of the buffer repeater at the op amp 13 is connected to the output of the op amp 2, the inverting input is connected to its own output and the input of the analog inverter 7, and the output of the buffer repeater at the op amp 13 is the output of the device.

The operation of the device is illustrated by timing diagrams (Fig. 3), which show:

- output voltage and ₉ GTI 9 (Fig. 3, a);

- input voltage devices and _Rin, and the output voltage of the analog inverter ₇ 7 (Figure 3b.);

- output voltage u _{10 of the} logical inverter 10 (Fig. 3, c);

- output voltage u _{8 of the} comparator 8 (Fig. 3, g);

- output voltage u _{12 of the} trigger 12 (Fig. 3, d);

- the output voltage u ₁₁ of the pulse shaper 11 (Fig. 3, e). A device for sampling an instantaneous voltage value operates as follows.

The GTI 9 generates rectangular pulses (Fig. 3a) that control the operation of the device. Consider, for example, the i-th interval of the device, starting at time t _i (Fig. 3). The output voltage of the GTI 9 through the logical inverter 10 is supplied, firstly, to the control input of the second key 6, and in the time interval t _i -t _{i + 0.5} this voltage is zero (Fig. 3c), so the second key 6 is open, and secondly, to the input of the pulse shaper 11, which generates a short pulse (Fig. 3e), which sets the trigger 12 to state "1" (Fig. 3d), since it is fed to the input of the asynchronous installation of the trigger in a single state. This output signal of the trigger 12 is fed to the control input of the first key 3, which closes at time t _i .

Input voltage and _Rin (FIG. 3b) from the source 1 is fed to an integrating op-amp consisting of op-amp 2, the resistor 4 and the storage capacitor 5, wherein at the time he begins to integrate the input voltage, output voltage, and _O (Fig. 3b shows the the voltage at the output of the analog inverter 7), in the interval [t _i ; t _{i + 0.5} ] varies in accordance with the expression (5)

Note that the initial voltage at the output of the integrating op-amp in each cycle is zero. Analog inverter 7 inverts this voltage

which is supplied to the comparator 8, to the other input of which the input voltage is also supplied.

When | and _O | _<Rin and the comparator 8 is in the state "0" (Figure 3c.) and does not affect the operation of the flip-flop 12. At time t _SEL (sampling time) | and _output | = and _input (Fig. 3b), which is fixed by the comparator 8 in the form of the presence of a voltage difference "0-1" at its output, trigger 12 is switched to a logical "0" state (Fig. 3d), which leads to the shutdown of the first key 3.

As a result, the capacitor 5 stores the voltage, which is equal to the instantaneous value of the input voltage at time t _select , i.e. sampling of instantaneous value is performed. The storage time is equal to (t _{i + 0.5} -t _select ) (Fig. 3b), during which you can use the obtained information about the value of the sample in accordance with the tasks. During the time interval (t _{i + 1} -t _{i + 0.5} ), the second key 6 closes (a single signal from the output of the logical inverter 10 is supplied to its control input) and the capacitor 5 discharges, and at time t _{i + 1} (Fig. . 3) the next cycle begins.

The analog inverter 7 can be performed in the usual way based on the op-amp and two resistors (at the input and in the negative feedback circuit), and the pulse shaper 11 can be made on the basis of a standby multivibrator or single vibrator.

Since, in the proposed device, the load of the integrator, made on the basis of the OS, acts as a buffer repeater on OS 13, in which case the condition is true

where R in. _BP is the input resistance of the buffer repeater at OS 13, then, taking into account (2), (3) and (4), the statement is valid

Given that in the proposed device, the load resistance of the device does not affect the value of R _{input BP} , it is legitimate to assert the formation of a sample of the instantaneous voltage value, regardless of the load resistance of the device, and therefore increase the accuracy when sampling the instantaneous voltage value.

Claims (1)

A device for sampling an instantaneous voltage value containing an op-amp, the non-inverting input of which is grounded, and the inverting input is connected to the input voltage source through the first key and resistor, a storage capacitor is connected in the negative feedback circuit of the op-amp, in parallel with which the second key is connected, the analog inverter is connected to non-inverting input of the comparator, the inverting input of which is connected to the input voltage source, and the output - with the input of the installation in the zero state of the trigger, the output is of the latter is connected to the control input of the first key, and the input of the unit to the single state of the trigger, through the pulse shaper, is connected to the output of the clock pulse generator, which is connected through the logic inverter to the control input of the second key, characterized in that the buffer repeater at the op-amp is introduced into the device, moreover, its non-inverting input is connected to the output of the op-amp, and the inverting input is connected to its own output and the input of the analog inverter, the output of the buffer repeater to the op-amp serves as the output of the device.

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