A three-out-of-two voting control circuit with disconnection detection function

Abstract

The invention discloses a two-out-of-three voting control circuit, which receives three-way passive switch quantity signals, and outputs one-way passive switch quantity signal after being processed by the voting circuit logic; when any one or more of the three-way passive switch quantity signals are disconnected, a disconnection fault signal can be output; when the three-way passive switch quantity signals have no disconnection fault, any two or more of the signals are valid, and one-way passive switch quantity signal can be voted to be output; when any one of the three-way passive switch quantity signals has a disconnection fault, the voting function fails; the invention can effectively perform two-out-of-three voting, effectively identify line disconnection signals, does not require additional program processing, has a simple circuit structure, is low in application cost, and has a high safety factor. Compared with the relay voting circuit, the control circuit of the invention has the advantages of less wiring and fewer fault points.

Description

Technical Field

[0001] The invention relates to an emergency diesel engine generator set control system in a special application field, and in particular to a two-out-of-three voting control circuit with a line break detection function. Background Art

[0002] The emergency generator set starting control system refers to a control system that automatically starts the emergency generator set for emergency power supply when the power system loses power; it is mainly used in places with high requirements for power supply reliability.

[0003] Emergency diesel generator sets in special application fields have high requirements on the safety protection function of the control system. In order to avoid the phenomenon that the protection function of the control system is falsely triggered due to erroneous signals, the control system adopts a three-out-of-two judgment strategy for signal collection of protection shutdown functions such as overspeed and low lubricating oil pressure.

[0004] If the emergency generator start control system involves a three-out-of-two voting output emergency start signal, almost all of them adopt the relay voting method. The principle is to use three relays, each relay has at least two groups of contacts, and any two relays are connected in series and then in parallel to form a three-out-of-two voting circuit; however, this three-out-of-two voting circuit has many external wiring and many fault points. When a disconnection occurs in the switch circuit, it is impossible to detect the fault in time and send out an alarm signal. When the switch signal is valid, there is a risk of ineffective voting. This patent connects a voltage-stabilizing diode in parallel at both ends of each group of switch signal contacts. When the connecting cable between the switch and the voting module is disconnected, a disconnection fault alarm can be effectively issued. Summary of the invention

[0005] The purpose of the present invention is to provide a three-out-of-two voting control circuit, which can effectively solve the problems of multiple external wiring and multiple fault points in the three-out-of-two voting circuit of the relay, can effectively detect the voting signal disconnection fault, is easy to install, operate and maintain, reduces the workload of wiring and checking, and has a modular design that facilitates later maintenance.

[0006] The present invention adopts the following technical solutions to achieve the above-mentioned purpose:

[0007] A two-out-of-three voting control circuit, comprising a voting module and a signal output module, characterized in that: the voting module comprises three switches, namely S1, S2, and S3, wherein S1, S2, and S3 are three-way passive switch signal input ports, and each switch is connected in parallel with a 1N4733A diode; each input port of the voting module is connected in parallel with a resistor R1, R2, and R3 with the same resistance value, and the three resistors connected in parallel with the ports are connected in series with a resistor R4 with the same resistance value to form a loop;

[0008] The voting module also includes two comparators LM393D, wherein the first LM393D in-phase input terminal detects the voltage U1 between R3 and R4, and the inverting input terminal detects the voltage U2 between R6 and R7; when the voltage U1 between R3 and R4 is greater than the voltage U2 between R6 and R7, the first LM393D outputs a high level through the pull-up resistor R10, drives BC846 and the back-end drive circuit, and the K1 relay contact is closed; when the voltage U1 between R3 and R4 is less than the voltage U2 between R6 and R7, the first LM393D outputs a low level through the pull-up resistor, and BC846 and the back-end drive circuit do not work. The K1 relay contact is disconnected; the non-inverting input terminal of the second comparator LM393D detects the voltage U3 between R8 and R9, and the inverting input terminal detects the voltage U1 between R3 and R4; when the voltage U1 between R3 and R4 is less than the voltage U3 between R8 and R9, the second LM393D outputs a high level through the pull-up resistor R11, drives BC846 and the back-end drive circuit, and the K2 relay contact is closed; when the voltage U1 between R3 and R4 is greater than the voltage U2 between R6 and R7, the second LM393D outputs a low level through the pull-up resistor, BC846 and the back-end drive circuit do not work, and the K2 relay contact is disconnected.

[0009] When any one or more of the three passive switch signals are disconnected, a disconnection fault signal can be output; when there is no disconnection fault in the three passive switch signals, any two or more signals are valid and a vote can be cast to output one passive switch signal; when any one of the three passive switch signals is disconnected, the voting function fails.

[0010] The present invention proposes a two-out-of-three voting control circuit, which adopts the above technical solution and has the following beneficial effects:

[0011] The present invention is aimed at the three-out-of-two voting output circuit involved in the emergency generator control system. Through the series-parallel circuit composed of resistors, diodes and switches, when different numbers of switches are closed, the comparator's in-phase input terminal has corresponding voltages. The effective number of switches and the disconnection fault are judged by the voltage comparison result, thereby realizing the three-out-of-two voting function with disconnection detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The invention discloses a two-out-of-three voting circuit with disconnection detection. DETAILED DESCRIPTION

[0013] The present invention will be further described below in conjunction with the accompanying drawings.

[0014] like Figure 1As shown, a three-out-of-two voting control circuit includes a voting module and a signal output module, characterized in that: the voting module includes three switches, namely S1, S2, and S3, and the S1, S2, and S3 are three-way passive switch signal input ports, and each switch is connected in parallel with a 1N4733A diode; the 1N4733A works in the reverse breakdown region, and the voltage at both ends is stable at 5.1V; each input port of the voting module is connected in parallel with a resistor R1, R2, and R3 with the same resistance value, and the three resistors connected in parallel with the ports are connected in series with a resistor R4 with the same resistance value to form a loop;

[0015] The voting module includes two comparators LM393D, one of which has a non-inverting input terminal detecting the voltage U1 between R3 and R4, and an inverting input terminal detecting the voltage U2 between R6 and R7; the other comparator LM393D has a non-inverting input terminal detecting the voltage U3 between R8 and R9, and an inverting input terminal detecting the voltage U1 between R3 and R4; ; .

[0016] The output module includes two transistors BC846 (Q1, Q2) and two relays (K1, K2).

[0017] When the voltage U1 between R3 and R4 is greater than the voltage U2 between R6 and R7, LM393D outputs a high level through the pull-up resistor R10, driving BC846 and the back-end drive circuit, and the K1 relay contact is closed; when the voltage U1 between R3 and R4 is less than the voltage U2 between R6 and R7, LM393D outputs a low level through the pull-up resistor, BC846 and the back-end drive circuit do not work, and the K1 relay contact is disconnected;

[0018] When the voltage U1 between R3 and R4 is less than the voltage U3 between R8 and R9, LM393D outputs a high level through the pull-up resistor R11, driving BC846 and the back-end drive circuit, and the K1 relay contact is closed; when the voltage U1 between R3 and R4 is greater than the voltage U2 between R6 and R7, LM393D outputs a low level through the pull-up resistor, BC846 and the back-end drive circuit do not work, and the K1 relay contact is disconnected.

[0019] When any one or more of the three passive switch signals are disconnected, a disconnection fault signal can be output; when there is no disconnection fault in the three passive switch signals, any two or more signals are valid and a vote can be cast to output one passive switch signal; when any one of the three passive switch signals is disconnected, the voting function fails.

[0020] Each working state will be described below.

[0021] When the three switch circuits S1, S2, and S3 are normal and all switches are disconnected .

[0022] When the three switches S1, S2, and S3 are closed, the circuit is normal, two are open and one is closed. .

[0023] When the three switch circuits S1, S2, and S3 are normal, one is open and the other two are closed .

[0024] When the S1, S2, and S3 circuits are normal and all three switches are closed .

[0025] In summary, when the system is not disconnected, the voltage of U1 is always higher than that of U3, U2B LM393AD outputs a low level through the pull-up resistor, BC846 and the back-end drive circuit do not work, the K2 relay contact is disconnected, and the disconnection signal is not output. When the system is not disconnected and the number of closed switches among the three switches is greater than or equal to two ,LM393D outputs a high level through the pull-up resistor, driving BC846 and the back-end drive circuit, the K1 relay contact closes, and the voting signal is output; when the number of closed switches among the three switches is less than two , LM393D outputs a low level through the pull-up resistor, BC846 and the back-end drive circuit do not work, and the K1 relay contact is disconnected.

[0026] When one of the three switch circuits S1, S2, and S3 is broken, the other two switches are all disconnected.

[0027] When one of the three switch circuits S1, S2, and S3 is broken, the other two switches are one open and the other closed.

[0028] When one of the three switch circuits S1, S2, and S3 is disconnected and the other two switches are all closed .

[0029] When two of the three switch circuits S1, S2, and S3 are disconnected and the other switch is disconnected .

[0030] When two of the three switch circuits S1, S2, and S3 are disconnected and the other switch is closed .

[0031] When the three switch circuits S1, S2 and S3 are all disconnected .

[0032] In summary, when one line, two lines, or three lines are disconnected in the system, the voltage of U1 is always lower than that of U3, U2B LM393AD outputs a high level through a pull-up resistor, BC846 and the back-end drive circuit work, the K2 relay contact is closed, and a disconnection fault signal is output. The voltage of U1 is always lower than that of U2, U2B LM393AD outputs a low level through a pull-up resistor, BC846 and the back-end drive circuit do not work, the K2 relay contact is disconnected, and the voting signal is not output.

Claims

1. A two-out-of-three voting control circuit, comprising a voting module and a signal output module, characterized in that : The voting module includes three switches, namely S1, S2, and S3, which are three-way passive switch signal input ports, and each switch is connected in parallel with a 1N4733A diode; each input port of the voting module is connected in parallel with a resistor R1, R2, and R3 with the same resistance value, and the three resistors connected in parallel in the middle of the port are connected in series with a resistor R4 with the same resistance value to form a loop; The voting module also includes two comparators LM393D, wherein the first LM393D non-inverting input terminal detects the voltage U1 between R3 and R4, and the inverting input terminal detects the voltage U2 between R6 and R7; when the voltage U1 between R3 and R4 is greater than the voltage U2 between R6 and R7, the first LM393D outputs a high level through the pull-up resistor R10, drives BC846 and the back-end drive circuit, and the K1 relay contact is closed; when the voltage U1 between R3 and R4 is less than the voltage U2 between R6 and R7, the first LM393D outputs a low level through the pull-up resistor, and BC846 and the back-end drive circuit do not work. The K1 relay contact is disconnected; the non-inverting input terminal of the second comparator LM393D detects the voltage U3 between R8 and R9, and the inverting input terminal detects the voltage U1 between R3 and R4; when the voltage U1 between R3 and R4 is less than the voltage U3 between R8 and R9, the second LM393D outputs a high level through the pull-up resistor R11, drives BC846 and the back-end drive circuit, and the K2 relay contact is closed; when the voltage U1 between R3 and R4 is greater than the voltage U2 between R6 and R7, the second LM393D outputs a low level through the pull-up resistor, BC846 and the back-end drive circuit do not work, and the K2 relay contact is disconnected.

2. A two-out-of-three voting control circuit as claimed in claim 1, characterized in that: When any one or more of the three passive switch signals are disconnected, a disconnection fault signal can be output; when there is no disconnection fault in the three passive switch signals, any two or more signals are valid and a vote can be cast to output one passive switch signal; when any one of the three passive switch signals is disconnected, the voting function fails.

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