SU754317A1 - Current-to-pulse repetition frequency converter - Google Patents

Description

The invention relates to electrical engineering and can be used in automation and remote control systems, in particular, to convert signals from sensors, the output parameter of which is alternating current or voltage.

Known current Converter in the pulse repetition frequency, containing an integrating capacitor included in one diagonal of the bridge formed by key elements, the source of input current included in another diagonal of the bridge, control trigger, direct and inverse 15

the outputs of which are connected to the corresponding control inputs of the key elements, two threshold elements, the first inputs of which are connected to the output of the integrating capacitor, the second inputs to the outputs of the reference voltage source, the current sign identifier, whose input terminals are connected in series with the input current source the output is connected to the first inputs of the two elements AND [ΐ] ·

The input current source is connected to the converter input via a rectifier. it

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leads to errors that occur when changing the sign of the input current. So when changing the sign of the current, the derivative of the voltage on the integrating capacitor should change the sign in accordance with the accepted definition of the frequency-pulse modulation,

ί η

where η = 0,1,2,3, ... the sequence number of the output pulse, '

3 (ί) - input TCK, ‘

C is the capacitance of the integrating capacitor,

and _op is the reference voltage.

However, due to rectification of the input current, we have under the integral the absolute value of the current, and the voltage on the capacitor inside each sampling integral increases in one 25 direction, therefore the moment of appearance of the next pulse when the current sign changes in the known converter differs from that defined above. about 30 availability of error.

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The purpose of the invention is to improve the accuracy of conversion when the alternating input current.

This goal is achieved by the fact that an additional trigger, a differentiating circuit and a single vibrator are introduced into the current converter into the pulse frequency, with each input of an additional trigger connected to the output of the corresponding threshold element, and each output is connected via a differentiating circuit to the input of a single vibrator connected by its output with the second inputs of the two elements And, the outputs of both threshold devices through decoupling diodes are connected to the counting input of the control trigger.

The drawing shows a block diagram of the Converter.

The converter contains an integrating capacitor 1, included in one diagonal of the bridge formed by key elements 2-5, input current source 6, included in another diagonal of the bridge, control trigger 7, the forward and inverse outputs of which are connected to the corresponding control inputs of the key elements 2.5 and 3,4, two threshold elements 8 and 9, the first inputs of which are connected to the output of the integrating capacitor 1, the second inputs - to the terminals of the source of the reference voltage 10, the current indicator 11, the input outputs of which are included in series with the input current source 6, and the output is connected to the first two inputs-elements And 12 and 13, additional trigger 14, differentiating circuit 15 and one-shot 16, with each input of additional trigger 14 connected to the input of the corresponding threshold element, each output through differentiating the circuit 15 is connected to the input of the corresponding threshold element, and each output through the differentiating circuit 15 is connected to the input of the one-shot 16, connected by its output with the second inputs of the two elements And 12 and 13, the outputs of both n Horn devices 8 and 9 are connected through decoupling diodes 17 and 18 to the counting input of control trigger 7. Differentiating circuit 15 contains two elements: differentiating element 19 is connected by its input to the inverse output of additional trigger 14, and output through diode 20 to the input of one-shot 16 ; differentiating element 21 is attached respectively to the direct

the output of the trigger 14 and through the diode 22 to the control input of the one-shot

16. Output pulses are reduced at positive current from output 23, and at negative current from output 24 of the converter.

The Converter operates as follows.

Let the voltage on the integrating capacitor 1 is zero, the control trigger 7 is in a state in which the keys 2 and 5 are open, and the keys 3 and 4 are closed. Then, the integrating capacitor 1, depending on the sign of the current, is charged in positive or negative directions until threshold element 8 or 9 is triggered. At the same time, a pulse arrives at the counting input of control trigger 7, the trigger goes to another state, keys 2 and 5 close open keys 3 and 4, i.e. a reverse switching of the current source 6 occurs with respect to the integrating capacitor 1. Then the process repeats.

When the input current is unchanged, the pulses to the counting input of the control trigger 7 are received alternately from the outputs of the threshold elements 8 and 9. In addition, the pulses from the outputs of the threshold elements 8 and 9 are fed alternately to the inputs of the additional trigger 14. When tipping the trigger 14, the negative front one of the two mutually inverted trigger outputs, passing through the differentiating element 19 (21) and diode 20 (22), triggers the one-shot 16. The signal from the output of the one-shot 16 goes to the second inputs of the And 12 and 13 elements.

If the input current is positive, then the output signals of the current indicator mark 11 allow the signal from the output of the one-shot 16 to exit 23 of the first element 12 and prohibit its passage to the output 24 of the second element 13. At a negative input current, pulses appear at the output of the second element 13 and absent at the output of the first element And 12.

When the current sign changes, when the alternating current amplitude is so small that after integrating it on capacitor 1, the voltage on this capacitor changes to within less than the reference voltage, two cases are possible: when the alternating voltage on the integrating capacitor does not reach the threshold voltage or when on the integrating capacitor reaches the threshold value. In the latter case, each time the threshold element 8 is triggered, the control trigger 7 is transferred and

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reverse input current switching. The next pulse at the output of the converter should appear when the increment of the voltage on the capacitor since the appearance of the previous pulse is 5

equal to the reference voltage. To determine the specified voltage increment, an additional trigger 14 is used, the number of overturning of which is equal to the number of transitions. "The voltage on the integrating condensation ^and torus 1 s of the threshold element 8 to the trigger level of the threshold element 9 to back.

So in the proposed ^ 5

The frequency converter modulation method is exactly implemented in the converter.

Claims (1)

Claims 20 Current-to-pulse frequency converter containing an integrating capacitor included in one diagonal of the bridge formed by 25 key elements, input current source included in another diagonal of the bridge, control trigger, direct and inverse outputs of which are connected to the corresponding control inputs of the key elements, two threshold element, the first inputs of which are connected to the output of the integrating capacitor, the second inputs - to the terminals of the reference voltage source, the determinant of the sign of the current, the input terminals dyons are connected in series with the input current source, and the output is connected to the first inputs of two I elements, characterized in that, in order to increase the conversion accuracy with alternating input current, an additional trigger, a differentiating circuit and a one-shot are introduced, with each additional trigger input connected with the output of the corresponding threshold element, and each output is connected through a differentiating circuit, to the input of a one-shot, connected by its output with the second inputs of two elements And, output s both threshold devices through decoupling diodes are connected to the count input of the control latch.