RU2618356C1 - Multichannel voltage comparator with galvanic isolated channels - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: multichannel voltage comparator with galvanical isolated channels comprises a clock generator, a binary counter of the controlled channel number, decoder, memory code values of controlled voltage and type code of control, DAC, voltage comparator, a digital logic element "XOR", output fixation voltage trigger for setpoint, analog multiplexer, device startup bus, voltage selection line, voltage survey line, voltage limited code line, resistors, limiting the input current surges when the input voltage changes, transistor optocouplers, capacitors, reverse voltage protection diodes, pulse transformers, variable resistors.

EFFECT: no need in separate, galvanical isolated voltage supply sources.

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Description

The invention relates to automatic control and monitoring systems, in particular, for fixing the case of voltage output of galvanically isolated or under different potentials voltage sources beyond the set values.

The closest in technical essence is a galvanically isolated voltage comparator powered by an input signal according to patent No. 2540808, which contains an adjustable zener diode, a diode optocoupler, a CMOS chip with a Schmitt trigger and five resistors, which provides galvanic isolation from the input signal and does not require an isolated power source.

The disadvantage of this voltage comparator is the fixed level of comparing voltage with a large value of the minimum level of comparing voltage, determined by the voltage drop at the adjustable zener diode (2.5V), the optocoupler LED (approximately 1.5V) and the current-sensing resistor of the optocoupler LED.

The purpose of the invention is to create a multi-channel voltage comparator with galvanically isolated channels that do not require additional voltage sources and set levels of voltage comparing via an interface, individually for each channel.

A multi-channel voltage comparator with galvanically isolated channels is proposed, which contains a clock pulse generator, a binary counter of the number of monitored channels, a decoder, DAC, RAM for the codes of the values of the monitored voltages and a code for the type of control, a voltage comparator, an exclusive OR digital logic element, a trigger for fixing the case of controlled input voltage for the set value, analog multiplexer, device start-up bus, controlled voltage polling line, trunk l setting the level of comparing the controlled voltage, resistors limiting the surge of input currents from changes in input voltages, transistor optocouplers, capacitors, protection diodes against reverse input voltage, pulse transformers, variable resistors.

The main purpose of a multi-channel voltage comparator with galvanically isolated channels is the alternate monitoring of the voltage of various sources and fixing the case of voltage output of the monitored voltage source beyond the value set for it.

The drawing shows a structural diagram of a multi-channel voltage comparator with galvanically isolated channels.

The drawing shows:

1 - resistor, limiting the surge of the input current when the input voltage changes;

2 - transistor optocoupler;

3 - capacitor;

4 - diode protection against reverse input voltage;

5 - pulse transformer;

6 - variable resistor;

7 - analog multiplexer;

8 - binary counter of the number of monitored channels;

9 - clock generator;

10 - decoder;

11 - RAM codes of the values of the level of comparing the controlled voltage and the code type of control;

12 - DAC;

13 - voltage comparator;

14 - digital logic element "Exclusive OR";

15 - trigger fixing the case of output of the controlled input voltage beyond the set value;

Uвx.1 - Uвx.n - measuring inputs;

OV.1 - OV.n - general conclusions of measuring inputs;

+ U - voltage supplying devices;

OV - the overall output of the device;

Start - device launch bus;

M - trunk for the selection of controlled voltage;

N - line polling controlled voltage;

H - trunk code limit value of the controlled voltage;

Failure - a voltage output signal in a controlled channel beyond the set value of the comparing voltage.

A multi-channel voltage comparator with galvanically isolated channels operates as follows.

In each channel of the multichannel comparator, the capacitor 3 is charged through the measuring input and resistor 1 to the voltage of the connected voltage source. The low logic level of the signal in the Start bus keeps the binary counter of the number of monitored channels 8 in the initial state, the trigger for fixing the case of the output of the monitored voltage exceeding the set value 15 and blocks the operation of the clock generator 9.

A multi-channel voltage comparator with galvanically isolated channels starts to work when switching to a high logical signal level in the Start bus. The coincidence of the enable signals at the inputs of the clock generator 9 will start the generator. The binary counter of the number of monitored channels 8 will establish the code of the first channel in the line for selecting the monitored voltage M. Using the code in line M of the RAM, the codes of the value of the comparison level of the monitored voltages and the code of the type of control 11 will set the code of the value of the voltage of the comparator in the line H and the code of the type of control for the first channel, the analog multiplexer 7 will connect the first channel to the direct input of the voltage comparator 13, the decoder 10 will turning on the optocoupler transistor 2 of the first channel. DAC 12 on the code in the line of the limit value of the monitored voltage H sets at the inverse input of the comparator 13 the comparing voltage for the first channel.

The low-level decoder 10 from the output of the clock generator 9 will turn on the transistor 2 optocoupler of the first channel, the transistor of which will connect the capacitor 3 of the first channel to the primary winding of the pulse transformer 5 of the first channel. A voltage pulse with an amplitude proportional to the input voltage of the first channel is formed on the secondary winding of the pulse transformer 5 of the first channel. The voltage pulse through the variable resistor 6 of the first channel, which serves to compensate for the spread of the transfer coefficient of the pulse transformer 5, and the analog multiplexer 7 will go to the direct input of the comparator 13. At the time of exceeding the pulse voltage from the analog multiplexer 7, the comparing voltage for the first channel installed on the inverse input of the comparator 13, a high logic level is formed at the output of the latter.

The exclusive OR gate 14 determines the type of channel control. If the logical code 0 is stored in the RAM of the control type code 11 for a given channel, then the output of the “Exclusive OR” logical element 14 will be logical 1 with a logical 1 at the output of the comparator 13, therefore, this channel detects when the input voltage exceeds the set value of the comparing voltage for this channel . If in RAM code of control type 11 for a given channel logic 1 is set, then the output of the “Exclusive OR” logical element 14 will be logical 1 with a logical 0 at the output of comparator 13, therefore this channel detects a decrease in the input voltage below the set value of the comparing voltage for this channel .

The front of the negative impulse from the clock generator 9 will record the control result in the fixation trigger of the controlled voltage output for the set value 15 and increase the code value in the binary counter of the monitored channel number 8 by 1. If 0 is written in the fixation trigger of the controlled voltage output for the set value 15 that corresponds to finding the voltage at the input of the controlled channel in the tolerance, the next pulse from the clock generator 9 will start the voltage control in the next eat the channel. The recording in the trigger of fixing the case of the output of the controlled voltage beyond the set value 15 of logical 1 corresponds to finding the voltage at the input of the controlled channel out of tolerance. This logical 1 at the inverse input of the clock 9 blocks its operation and the work of a multi-channel voltage comparator with galvanically isolated channels.

The polling time of one channel in a multi-channel voltage comparator with galvanically isolated channels depends on the parameters of the optocoupler transistor 2, pulse transformer 5 and is a few microseconds. The pause duration, when accessing one channel, depending on the number of channels in the multi-channel voltage comparator, should ensure the charge of the capacitor 3 through the resistor 1 to the voltage of the controlled voltage source.

If necessary, control the voltage source for maximum and minimum values using two channels of a multi-channel comparator. In one channel, the type of control is set to exceed the controlled voltage of the set upper voltage value, in the other - to reduce the controlled voltage below the set lower value. If it is necessary to control the voltage source by the maximum and minimum values in the bipolar range, two channels of a multichannel comparator are used and in one channel the Uvx terminals are interchanged. and OV. To protect the channel from the reverse input voltage, diode 4 is used.

Galvanic isolation of each channel in a multi-channel voltage comparator is carried out by a pulse transformer 5 and a transistor optocoupler 2.

Claims (1)

Multichannel voltage comparator with galvanically isolated channels, containing a clock pulse generator, a binary counter of the channel number to be monitored, a decoder, RAM for the codes of the values of the controlled voltages and a code for the type of control, a DAC, a voltage comparator, an exclusive OR digital logic element, a trigger for fixing the case of a controlled input output voltage per set value, analog multiplexer, device start-up bus, controlled voltage selection line, con polling line the voltage being rolled, the line of the code for the limit value of the controlled voltage, resistors that limit the surge of the input current when the input voltage changes, transistor optocouplers, capacitors, reverse input voltage protection diodes, pulse transformers, variable resistors, moreover, the measuring input of each channel is connected to the first output of the resistor limiting surges of the input current when the input voltage changes, the second output of the resistor is connected to the collector of the transistor of the optocoupler transistor oh, the first output of the capacitor and the cathode of the diode for protection against reverse input voltage, the emitter of the transistor optocoupler transistor is connected to the positive terminal of the input winding of the pulse transformer, the common terminal of the measuring input of each channel is connected to the second terminal of the capacitor, the negative terminal of the input winding of the pulse transformer and the anode of the diode against reverse input voltage, the positive terminal of the output winding of the pulse transformer in each channel is connected to the first terminal alternately of the resistor, the second output of which is connected to the corresponding input of the analog multiplexer, the negative output of the output winding of the pulse transformer in each channel of the voltage comparator is connected to the common output of the device, the start bus of the device is connected to the direct enable input of the clock generator, the inverse of the installation to the initial state of the binary counter the number of the controlled channel, by the inverse input of the installation to the initial state of the trigger for fixing the case of the output of the controlled voltage Based on the set value, the inverse output of the clock generator is connected to the inverse input of the decoder resolution and the direct dynamic inputs of the binary counter of the number of the controlled channel and the trigger for fixing the case of the output of the controlled voltage beyond the set value, the trunk for selecting the controlled voltage from the output of the binary counter of the number of the controlled channel is connected to the address the inputs of the analog multiplexer, decoder and RAM codes for the values of the controlled voltages and code type con a role, each bus of the line for interrogating the controlled voltage from the decoder output is connected to the cathode of the optocoupler LEDs of the transistor corresponding channel, the anodes of the transistor LEDs are connected to the supply voltage of the device, the line of the code for the limit value of the controlled voltage from the RAM output of the codes for the values of the controlled voltages is connected to the DAC inputs, the code bus type of control from the RAM output is connected to the first input of the exclusive OR digital logic element, the DAC output is connected to the inverse the input of the voltage comparator, the direct input of which is connected to the output of the analog multiplexer, the output of the voltage comparator is connected to the second input of the digital logic element “Exclusive OR”, the output of which is connected to the input D of the trigger for fixing the case of the output of the controlled voltage to the set value, the output of the trigger for fixing the case of the output of the controlled voltage for the set limit value is connected to the inverse input of the resolution of the clock generator and is the output of a multi-channel comparator voltage galvanically isolated channels.

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