SU758177A1 - Device for computing relative difference of two dc voltages - Google Patents

Description

The invention relates to the field of analog computing and can find application in the field of information and measuring equipment.

A device designed to obtain a voltage proportional to the relative difference of two DC voltages, containing two exponential voltage generators, two comparison circuit, the amplifier voltage difference VD. However, such a device has a large error determined by the error components of all the blocks included in the circuit.

The closest technical solution is a dividing device for mixed signals containing the first toggle key, the input of which is connected to the input of an operational amplifier through a large-scale resistor, the integrating capacitor is included in the negative feedback, the second toggle switch, the fixed contact of which is connected to the input and movable to the output of the operational amplifier, the comparison circuit, one input of which is connected to the output of the operational amplifier, the second input

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connected to a pulse voltage divider, and the output is connected to the trigger counting input, the trigger output is connected to the control input of the first 5 conversion key, the input of the pulse voltage divider is connected to the filter input, the output of which is connected to the second trigger input [2]. The disadvantage of the prototype is a large calculation error, due to the large weighting factor of the error component of the operational amplifier, especially when subtracting close input voltages, and the error of the division operation, determined by the influence of the integrator slope on the intermediate conversion of the quotient to the pulse duration.

The aim of the invention is to improve the accuracy of the device.

A device is proposed for calculating the relative difference of two DC voltages, containing the first reversing switch, whose inputs are the device inputs, the first large-scale resistor connected to the input of the first operational amplifier, and the negative feedback includes the first 758177

a second integrated capacitor, a second toggle key whose fixed contact is connected to the input, and a comparative circuit movable to the output of the first operational amplifier, one input of which is connected to the output of the first operational amplifier, and the output of the comparison circuit connected to the counting input of the first trigger, the output of the first trigger connected to the control input of the first switch-over key, and a filter, characterized in that, in order to improve accuracy, a second large-scale resistor, a second operational amplifier, and a second th integrating capacitor, a third cross over key and a second trigger; the second large-scale resistor is connected to the input of the second operational amplifier, the negative integrating of which includes the second integrating capacitor, the third reversing key, one fixed contact of which is connected to the input of the second operational amplifier, the second counting input the trigger is connected to the output of the first trigger, and the outputs to the control inputs of the second and third cross over keys, the second fixed contact of the third cross over key connected to the fixed contact of the second key and to the input of the comparison circuit, a movable contact of the first cross over key is connected to the second input of the comparison circuit, inputs of large-scale resistors are connected to the first fixed contact of the first reversible key and to the terminal of the first input voltage. terminal of the second input voltage.

Diagram of the device shown in the drawing.

► A device for calculating the relative difference of two DC voltages contains terminal 1 of the first input voltage, the first large-scale resistor 2, the first operational amplifier 3, the first integrating capacitor 4, the second large-scale resistor 5, the second operational amplifier 6, the second integrated capacitor 7, the first convertible key 8, second cross over key 9, third cross over key 10, comparison circuit 11, first trigger 12, second trigger 13, terminal 14 of the second input voltage, filter 15, reference voltage source 16.

Elements 2; 3 and 4 form the first integrator, and elements 5, 6 and 7 form the second integrator.

The device works as follows.

The first input voltage from terminal 1 is fed to the inputs of the integrators. Let the position of the contact reversible keys 8, 9, 10 is such that the output voltage and _g from terminal 14

(0

15

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25

thirty

35

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45

50

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through the key 8 is fed to one input of the comparison circuit 11 and the first integrator has a transfer coefficient Kp. The voltage at the output of this integrator begins to increase and at the time of equality

q · and _£ · «= and _g , whence ΐρ7 ^,

the comparison circuit 11 is activated. Its output signal, trigger 12, switches to the opposite position, connecting terminal 1 of the input voltage 11p to the input of the comparison circuit 11. The voltage at the output of the first integrator continues to increase even at the time of equality

^T G ^and G ^K 1 ” ^and 1 'from T _{1 =} D-,

the comparison circuit 11 is again triggered, triggering the trigger 12 to the initial state. The pulse duration at the output of this trigger is equal to

The output signal of the trigger 12 flip key 8 is set to its original state, and the trigger 13 - in the opposite. The output signals of the trigger 13 translate the toggle key 9 in a state in which the discharge of the first integrating capacitor 4; and the key 10 is in the state ensuring the normal operation of the second integrator.

Now the second integrator is working, the transmission coefficient of which is K _g . By analogy with the previous one, when the first integrator worked, you can get

. _ and ₇ ι ι_ ^{12 = to} 2 ^and 1

C1-C2 ^and 1 '

After the second integrator finishes, the first integrator starts working again, and so on. The output pulses of the trigger 12 are fed to the input of the filter 15, where they are modulated in amplitude by voltage 1) _{0 of the} voltage source 16 and the selection of the DC component, which is equal to

δΙ. + δΕ? . 4.-112 ^and out ~ ^and o ' ^to η- - ^К ' ⁰ о _and ^:

where K is the block transfer coefficient. Thus, the proposed device allows to calculate the relative difference between the two DC voltages with high accuracy, since it eliminates the error from the change in the slope of the integrator and there is no differential amplifier in the circuit, and consequently, its error. It also excludes the error of the comparison scheme №1 when performing the operation of subtracting the close ones.

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five

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largest stress, which is prevalent because it has a weight, a coefficient inversely proportional to the relative difference being converted.

Claims (1)

Claims $ A device for calculating the relative difference of two DC voltages, containing the first switch key whose inputs are the device inputs, the first large-scale resistor connected to the input of the first operational amplifier whose negative feedback includes the first integrated capacitor, the second switch key, fixed the contact of which is connected to the input, and the movable one to the output of the first operational amplifier, the comparison circuit, one input of which is connected to the output of the first operating device and the output of the comparison circuit is connected to the counting input of the first trigger, the output of the first trigger is connected to the control input 25 of the first reversing key, and a filter, characterized in that, in order to improve the accuracy, a second scale resistor, a second operational amplifier, and a second integration capacitor , the third cross over key and the second trigger, the second large-scale resistor connected to the input of the second operational amplifier, the negative integrator of which includes the second integrating capacitor, the third cross-coupling key, one fixed contact of which is connected to the input of the second operational amplifier, the counting input of the second trigger connected to the output of the first trigger, and the outputs to the control inputs of the second and third cross over keys, the second fixed contact of the third cross over key is connected to the fixed contact The second key and with the input of the comparison circuit are connected to the second input of the comparison circuit the moving contact of the first toggle key, the inputs of the scale resistors are connected to the first fixed contact of the first toggle key and to the terminal of the first input voltage, the second fixed contact of the first key is connected to the terminal of the second input voltage .