Relay adhesion detection circuit and relay adhesion detection system

Abstract

The invention relates to a relay adhesion detection circuit and a relay adhesion detection system, and belongs to the field of relay detection. The relay adhesion detection circuit comprises an acquisition circuit, a negative feedback operational amplifier and a level conversion circuit. The level conversion circuit comprises a comparator; a live wire acquisition branch of the acquisition circuit is connected with the output side of a relay on a live wire; a zero line acquisition branch of the acquisition circuit is connected with the output side of a relay on a zero line; the live line acquisition branch and the zero line acquisition branch are respectively connected with two input ends of the negative feedback operational amplifier; the in-phase input end of the negative feedback operational amplifier is connected with a first reference signal; the comparator is connected with the negative feedback operational amplifier and is also connected with a second reference signal; and when the live wire contact and the zero wire contact are disconnected, but the output of the comparator is detected to be a square wave signal, the relay is judged to be adhered. According to the invention, the complexity of relay adhesion detection can be reduced.

Description

Technical Field

[0001] The invention relates to a relay adhesion detection circuit and a relay adhesion detection system, belonging to the field of relay detection. Background Art

[0002] The situation where the relay cannot be disconnected in the energized state is called relay sticking. When the relay sticks, the current in the circuit cannot be disconnected normally, causing the electrical equipment to remain in the on state, which in turn causes the electrical equipment to overload or overheat, and even cause the electrical equipment to burn out and may cause personal injury to the operator.

[0003] In order to reduce the occurrence of safety problems in the use of electrical equipment caused by relay adhesion, the relevant technology provides a relay adhesion detection circuit, which can be referred to Figure 1 When the relay is detected to be sticking, the power supply end will be disconnected to protect the human body and the powered equipment.

[0004] Figure 1 It is an existing relay adhesion detection circuit, such as Figure 1 As shown, the relay adhesion detection circuit includes: an operational amplifier U12A for collecting the voltage on the input side of the relay on the live wire and the neutral wire, an operational amplifier U11A for collecting the voltage on the output side of the relay on the live wire and the neutral wire, an optocoupler isolation module connected to the output end of the operational amplifier U11A and the output end of the operational amplifier U12A, a control module connected to the optocoupler isolation module, two current limiting resistors are connected in series on the in-phase input end and the in-phase input end of the operational amplifier U11A, and two current limiting resistors are connected in series on the in-phase input end and the in-phase input end of the operational amplifier U12A.

[0005] like Figure 1 In the relay adhesion detection circuit shown, the input side collects a voltage, compares it with the threshold voltage, and outputs a signal; the output side collects a voltage, compares it with the threshold voltage, and outputs a signal; the control module determines whether there is adhesion by judging whether the level values ​​of the two signals are similar. If they are similar, it is considered that there is adhesion, and if they are not similar, it is considered that there is no adhesion. However, since this scheme requires sampling and voltage threshold comparison of the voltage signals on both the input and output sides of the relay, and requires an optocoupler isolation module or other isolation module, the detection scheme is complex and the cost is high. Summary of the invention

[0006] The object of the present invention is to provide a relay adhesion detection circuit and a relay adhesion detection system, so as to solve the problems of complexity and high cost of the relay adhesion detection circuit in the prior art.

[0007] To achieve the above object, the solution of the present invention includes: A relay adhesion detection circuit of the present invention comprises an acquisition circuit, a negative feedback operational amplifier and a level conversion circuit; The acquisition circuit includes a live line acquisition branch and a neutral line acquisition branch; the level conversion circuit includes a comparator; The input end of the live wire acquisition branch is used to connect to the output side of the live wire contact of the relay connected in series on the live wire; the input end of the neutral wire acquisition branch is used to connect to the output side of the neutral wire contact of the relay connected in series on the neutral wire; the output end of the live wire acquisition branch and the output end of the neutral wire acquisition branch are respectively connected to the two input ends of the negative feedback amplifier; the in-phase input end of the negative feedback amplifier is also connected to the first reference signal; one input end of the comparator is connected to the output end of the negative feedback amplifier, and the other input end is connected to the second reference signal; When the live wire contact and the neutral wire contact are disconnected, but the comparator output is detected as a square wave signal, it is determined that the relay connected in series on the live wire and the relay connected in series on the neutral wire are stuck.

[0008] Further, the input end of the live wire collection branch is used to connect to the output side of the live wire contact of the relay connected in series on the live wire, including: when the live wire is a three-phase live wire, the input end of the live wire collection branch includes three contacts; There is a relay in series on each of the three-phase live wires; Each contact is connected to the output side of a relay's live contact.

[0009] Furthermore, a plurality of high-voltage sampling resistors for voltage division are connected in series on both the live line acquisition branch and the neutral line acquisition branch.

[0010] Furthermore, high-voltage isolation capacitors for isolating DC components are connected in series on both the live line collection branch and the neutral line collection branch.

[0011] Furthermore, it also includes: a current limiting resistor connected in series between the non-inverting input terminal of the negative feedback operational amplifier and the first reference signal for current limiting.

[0012] Furthermore, it also includes: a filtering and voltage stabilizing circuit connected in series between the output end of the negative feedback operational amplifier and the input end of the level conversion circuit, and used for filtering and stabilizing the signal output by the negative feedback operational amplifier.

[0013] Furthermore, the filtering and voltage stabilizing circuit includes an RC filter.

[0014] A relay adhesion detection system of the present invention comprises: a controller, the above-mentioned relay adhesion detection circuit; The controller is connected to the output end of the comparator; when the controller controls the live wire contact and the neutral wire contact to be disconnected, but detects that the comparator output is a square wave signal, it is determined that the relay connected in series on the live wire and the relay connected in series on the neutral wire are stuck.

[0015] Furthermore, when the controller determines that the relay connected in series on the live wire and the relay connected in series on the neutral wire are stuck, the controller controls all other relays to be powered off.

[0016] Furthermore, it also includes: an alarm module connected to the output end of the controller, which is used to give an alarm when the control module determines that the relay connected in series on the live wire and the relay connected in series on the neutral wire are stuck.

[0017] The beneficial effects of the present invention are as follows: as a pioneering invention, the relay adhesion detection circuit of the present invention comprises an acquisition circuit, a negative feedback operational amplifier and a level conversion circuit; the acquisition circuit comprises a live line acquisition branch and a neutral line acquisition branch; the level conversion circuit comprises a comparator; the input end of the live line acquisition branch is used to connect to the output side of the live line contact of the relay connected in series on the live line; the input end of the neutral line acquisition branch is used to connect to the output side of the neutral line contact of the relay connected in series on the neutral line; the output end of the live line acquisition branch and the output end of the neutral line acquisition branch are respectively connected to two input ends of the negative feedback operational amplifier; the in-phase input end of the negative feedback operational amplifier is also connected to a first reference signal; one input end of the comparator is connected to the output end of the negative feedback operational amplifier, and the other input end is connected to a second reference signal; when the live line contact and the neutral line contact are disconnected but it is detected that the comparator output is a square wave signal, it is determined that the relay connected in series on the live line and the relay connected in series on the neutral line are adhered. The live wire voltage and the neutral wire voltage on the output side of the relay in the AC circuit are collected by the collection circuit to understand the opening and closing state of the current relay. The live wire voltage and the neutral wire voltage are reduced and isolated by using two sets of high-voltage sampling resistors and negative feedback amplifiers on the live wire and the neutral wire, which can ensure the safety of the subsequent circuit; the signal output by the negative feedback amplifier is converted by the level conversion circuit, and a smoother and more stable detection signal can be obtained. When the live wire contact and the neutral wire contact are originally in a closed state, the comparator will output a square wave signal. At this time, if the live wire contact and the neutral wire contact are disconnected, the comparator continues to output a square wave signal, indicating that the live wire contact and the neutral wire contact are not disconnected, and the relay is adhered. The relay adhesion detection circuit of the present invention has a simple structure and a simple judgment logic, so the complexity of the relay adhesion detection circuit detection can be reduced, and the production cost can be reduced at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of an existing relay adhesion detection circuit; Figure 2 It is a structural schematic diagram of a relay adhesion detection circuit provided by an embodiment of the present invention; Figure 3 is a structural schematic diagram of another relay adhesion detection circuit provided by an embodiment of the present invention; Figure 4It is a structural schematic diagram of a relay adhesion detection system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0020] The idea of ​​the present invention is to determine whether the relay is stuck by only collecting the voltage on the output side of the relay in the AC circuit. The current opening and closing state of the relay can be understood by collecting the live wire voltage and the neutral wire voltage on the output side of the relay in the AC circuit using the collection circuit, and the live wire voltage and the neutral wire voltage are reduced and isolated by two sets of high-voltage sampling resistors and negative feedback amplifiers on the live wire and the neutral wire, which can ensure the safety of the subsequent circuit; the signal output by the negative feedback amplifier is converted by the level conversion circuit, and a smoother and more stable detection signal can be obtained. When the live wire contact and the neutral wire contact are originally in a closed state, the comparator will output a square wave signal. At this time, if the live wire contact and the neutral wire contact are disconnected, the comparator continues to output a square wave signal, indicating that the live wire contact and the neutral wire contact are not disconnected, and the relay is stuck. The relay sticking detection circuit of the present invention has a simple structure and a simple judgment logic, so the complexity of the relay sticking detection circuit detection can be reduced and the production cost can be reduced.

[0021] An embodiment of a relay adhesion detection circuit: Embodiment 1: Figure 2 is a structural diagram of a relay adhesion detection circuit provided by an embodiment of the present invention, such as Figure 2 As shown, the relay adhesion detection circuit includes an acquisition circuit 10 , a negative feedback operational amplifier 20 and a level conversion circuit 30 .

[0022] The acquisition circuit 10 includes a live line acquisition branch 101 and a neutral line acquisition branch 102 ; the level conversion circuit 30 includes a comparator U2A.

[0023] Specifically, the input end of the live wire acquisition branch 101 is used to connect to the output side L1_OUT of the live wire contact of the relay K1 connected in series on the live wire L1; the input end of the neutral wire acquisition branch 102 is used to connect to the output side N_OUT of the neutral wire contact of the relay K2 connected in series on the neutral wire N; the output end of the live wire acquisition branch 101 and the output end of the neutral wire acquisition branch 102 are respectively connected to the two input ends of the negative feedback operational amplifier 20; the in-phase input end ("+") of the negative feedback operational amplifier 20 is also connected to the first reference signal Vref1; one input end of the comparator U2A is connected to the output end of the negative feedback operational amplifier 20, and the other input end is connected to the second reference signal Vref2.

[0024] The live wire contact of the relay K1 is used to indicate the switch contact of the relay K1 for controlling the conduction and cutoff of the live wire; the neutral wire contact of the relay K2 is used to indicate the switch contact of the relay K2 for controlling the conduction and cutoff of the neutral wire.

[0025] Among them, the number of contacts at the output end of the live wire acquisition branch 101 is related to the number of phases of the alternating current, that is, if the alternating current is single-phase, the output end of the live wire acquisition branch 101 has only one contact; if the alternating current is three-phase, the output end of the live wire acquisition branch 101 has three contacts. Embodiment 1 of the present application takes the case where the alternating current is single-phase and the output end of the live wire acquisition branch 101 has one contact as an example for exemplary description.

[0026] In order to reduce the damage of the live high voltage AC to the subsequent circuit, as an optional implementation, a number of high voltage sampling resistors for current limiting and voltage division can be connected in series on the live acquisition branch 101. In order to meet the requirements of safety distance, the high voltage sampling resistors on the live line are respectively the first resistor R1, the second resistor R2 and the third resistor R3 as an example for illustrative description.

[0027] In order to reduce the damage of the high voltage alternating current on the neutral line to the subsequent circuit, as an optional implementation, a plurality of high voltage sampling resistors can be connected in series on the zero acquisition branch 102. In order to meet the requirements of the safety distance, the high voltage sampling resistors on the neutral line are respectively the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6 as an example for illustrative description.

[0028] Among them, the resistance values ​​of the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6 can be selected according to the implementation situation, and the present invention does not specifically limit this; for the types of the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6, the embodiments of the present invention will be exemplified by using a metal film or chip resistor with a rated voltage of 500 volts (V) or above.

[0029] In order to isolate the DC signal on the AC power, suppress surges, improve circuit insulation performance and save costs, as an optional implementation, a first high-voltage isolation capacitor C1 can be connected in series on the live line acquisition branch 101, and a second high-voltage isolation capacitor C2 can be connected in series on the neutral line acquisition branch 102.

[0030] Among them, the capacitance of the first high-voltage isolation capacitor C1 and the second high-voltage isolation capacitor C2 can be selected according to the implementation situation, and the present invention does not specifically limit this; as for the types of the first high-voltage isolation capacitor C1 and the second high-voltage isolation capacitor C2, the embodiments of the present invention will be exemplified by using ceramic capacitors with a withstand voltage of 500V or above.

[0031] Among them, the present invention does not specifically limit the position between the first high-voltage isolation capacitor C1 and the high-voltage sampling resistor on the live line, and the position relationship between the second high-voltage isolation capacitor C2 and the high-voltage sampling resistor on the neutral line. The following will take the first high-voltage isolation capacitor C1 connected in series between the input end of the live line acquisition branch 101 and the first resistor R1 as an example for exemplary description, and take the second high-voltage isolation capacitor C2 connected in series between the input end of the neutral line acquisition branch 102 and the fourth resistor R4 as an example for exemplary description.

[0032] As an optional implementation, the output end of the live wire acquisition branch 101 can be connected to the inverting input end (i.e., the "-" end) of the negative feedback amplifier 20, and the output end of the neutral wire acquisition branch 102 can be connected to the non-inverting input end (i.e., the "+" end) of the negative feedback amplifier 20; as another optional implementation, the output end of the live wire acquisition branch 101 can be connected to the non-inverting input end of the negative feedback amplifier 20, and the output end of the neutral wire acquisition branch 102 can be connected to the inverting input end of the negative feedback amplifier 20. The present invention does not make any special limitation to this, and the following takes the example that the output end of the live wire acquisition branch 101 can be connected to the inverting input end of the negative feedback amplifier 20, and the output end of the neutral wire acquisition branch 102 can be connected to the non-inverting input end of the negative feedback amplifier 20 as an example for exemplary description.

[0033] The negative feedback amplifier 20 includes an operational amplifier U1A. Pin 8 of the operational amplifier U1A (i.e., the power supply terminal of the operational amplifier U1A) is connected to the power supply voltage VCC, pin 4 of the operational amplifier U1A (i.e., the ground terminal of the operational amplifier U1A) is connected to the ground GND, pin 2 of the operational amplifier U1A (i.e., the inverting input terminal "-" of the operational amplifier U1A) is connected to the output terminal of the live line acquisition branch 101, pin 3 of the operational amplifier U1A (i.e., the non-inverting input terminal "+" of the operational amplifier U1A) is connected to the output terminal of the neutral line acquisition branch 102, and is also connected to the first reference signal Vref1, and a feedback resistor R7 is connected in series between pin 2 and pin 1 of the operational amplifier U1A.

[0034] The first reference signal Vref1 is provided by a stable DC power supply voltage, which can improve the detection accuracy of the operational amplifier U1A. The voltage amplitude of the first reference signal Vref1 can be selected according to actual conditions, and the present invention does not specifically limit this.

[0035] In order to prevent the current of the first reference signal Vref1 from being too large and causing damage to the operational amplifier U1A, as an optional implementation, a current limiting resistor R8 is further connected in series between pin 3 of the operational amplifier U1A and the first reference signal Vref1.

[0036] The resistance values ​​of the feedback resistor R7 and the current limiting resistor R8 can be selected according to actual conditions, and the present invention does not impose any special limitation on this.

[0037] Among them, pin 1 of the operational amplifier U1A (i.e., the output end of the operational amplifier U1A) can be connected to the non-inverting input end of the comparator U2A, or can be connected to the inverting input end of the comparator U2A, and the present invention does not specifically limit this. The following takes the example of pin 1 of the operational amplifier U1A being connected to the non-inverting input end of the comparator U2A as an example for exemplary description.

[0038] Among them, comparator U2A is essentially an operational amplifier, pin 8 of comparator U2A (i.e., the power supply terminal of comparator U2A) is connected to the power supply voltage VCC, pin 4 of comparator U2A (i.e., the ground terminal of comparator U2A) is connected to ground GND, pin 2 of comparator U2A (i.e., the inverting input terminal "-" of comparator U2A) is connected to the second reference signal Vref2, pin 3 of comparator U2A (i.e., the non-inverting input terminal "+" of comparator U2A) is connected to the output terminal of negative feedback operational amplifier 20, and pin 1 of comparator U2A (i.e., the output terminal of comparator U2A) is used to connect to a controller (not shown).

[0039] If pin 1 of the operational amplifier U1A is connected to the inverting input terminal of the comparator U2A, the second reference signal Vref2 is connected to the non-inverting input terminal of the comparator U2A. The voltage of the second reference signal Vref2 can be selected according to actual conditions, as long as the sine wave signal output by the operational amplifier U1A can be converted into a square wave signal and the first level signal output by the operational amplifier U1A can be converted into a low level signal. The present invention does not make any special restrictions on this.

[0040] In order to filter out the noise signal on the signal output by the operational amplifier U1A and improve the anti-interference performance of the relay adhesion detection circuit, as an optional implementation, a filtering and voltage stabilizing circuit 40 is also connected in series at the input end where the level conversion circuit 20 is connected to the negative feedback operational amplifier 20.

[0041] Among them, the filtering and voltage stabilizing circuit 40 can be an RC filter, or other filtering and voltage stabilizing chips or filtering and voltage stabilizing circuits. The present invention does not make any special limitation on this. The filtering and voltage stabilizing circuit 40 is an RC filter as an example for exemplary description.

[0042] Among them, the RC filter includes a ninth resistor R9 and a third capacitor C3, one end of the ninth resistor R9 is connected to the output end of the operational amplifier U1A, the other end of the ninth resistor R9 is respectively connected to the other end of the third capacitor C3 and the in-phase input end of the comparator U2A, and the other end of the third capacitor C3 is grounded GND.

[0043] Among them, the resistance value of the ninth resistor R9 can be selected according to actual conditions, and the present invention does not make any special restrictions on this; the capacitance value of the third capacitor C3 can be selected according to actual conditions, and the present invention does not make any special restrictions on this.

[0044] The following explains Figure 2 The working principle of the relay sticking detection circuit is provided.

[0045] When both relay K1 and relay K2 are in a closed state, the voltage collected by the live line acquisition branch 101 at the output side L1_OUT of relay K1 is a first sinusoidal wave voltage signal, and the voltage collected by the neutral line acquisition branch 102 at the output side N_OUT of relay K2 is a second sinusoidal wave voltage signal; the first sinusoidal wave voltage signal enters the inverting input terminal of the operational amplifier U1A after passing through the first high-voltage isolation capacitor C1 and the first resistor R1, the second resistor R2 and the third resistor R3, and the second sinusoidal wave voltage signal enters the non-inverting input terminal of the operational amplifier U1A after passing through the second high-voltage isolation capacitor C2 and the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6.

[0046] After the operational amplifier U1A raises the reference voltage to the first reference signal Vref1, the detection accuracy of the operational amplifier U1A is improved, so that the operational amplifier U1A can better detect the first sinusoidal voltage signal and the second sinusoidal voltage signal. The operational amplifier U1A can reduce the first sinusoidal voltage signal and the second sinusoidal voltage signal according to the feedback resistor R7 to form a third sinusoidal voltage signal, and the RC filter filters and stabilizes the third sinusoidal voltage signal. In order to facilitate the explanation of the principle, the filtered third sinusoidal voltage signal will be referred to as the first indication signal.

[0047] Comparator U2A compares the first indication signal with the second reference signal Vref2, sets the part of the first indication signal that is greater than the second reference signal Vref2 to a high level "1", and sets the part that is less than the second reference signal Vref2 to a low level "0", forming a square wave signal, and outputting it to the controller.

[0048] When both relay K1 and relay K2 are in the disconnected state, the voltage L1_OUT of the output side of relay K1 collected by the live line acquisition branch 101 is a 0-level signal, and the voltage N_OUT of the output side of relay K2 collected by the neutral line acquisition branch 102 is a 0-level signal; the operational amplifier U1A outputs a first-level signal based on the first reference signal Vref1 as a reference level, and the RC filter filters and stabilizes the first-level signal. In order to facilitate the explanation of the principle, the filtered first-level signal is subsequently referred to as the second indication signal.

[0049] The comparator U2A compares the second indication signal with the second reference signal Vref2. If the voltage value set by the second reference Vref2 is higher than the voltage value of the second indication signal, the comparator U2A will continuously output a low-level signal; if the voltage value set by the second reference signal Vref2 is lower than the voltage value of the second indication signal, the comparator U2A will continuously output a high-level signal. Whether it is continuously outputting a high-level signal or continuously outputting a low-level signal, it is a non-square wave signal.

[0050] When relay K1 and relay K2 are in the closed state and the control relay K1 and relay K2 are disconnected, if it is detected that the comparator U2A still outputs a square wave signal at this time, it means that relay K1 and relay K2 are not disconnected. At this time, relay K1 and relay K2 are closed but not disconnected and are stuck together; if it is detected that the comparator U2A outputs a non-square wave signal at this time, it means that relay K1 and relay K2 are disconnected and are not stuck together.

[0051] The relay adhesion detection circuit provided by the embodiment of the present invention uses the acquisition circuit to collect the live wire voltage and the neutral wire voltage on the output side of the relay in the AC circuit to understand the current opening and closing state of the relay, and uses two sets of high-voltage sampling resistors and negative feedback amplifiers on the live wire and the neutral wire to reduce and isolate the live wire voltage and the neutral wire voltage, so as to ensure the safety of the subsequent circuit; the signal output by the negative feedback amplifier is converted by the level conversion circuit, and a smoother and more stable detection signal can be obtained. When the live wire contact and the neutral wire contact are originally in a closed state, the comparator will output a square wave signal. At this time, if the live wire contact and the neutral wire contact are disconnected, the comparator continues to output a square wave signal, indicating that the live wire contact and the neutral wire contact are not disconnected, and the relay is adhered. The relay adhesion detection circuit has a simple structure and a simple judgment logic, so the complexity of the relay adhesion detection circuit detection can be reduced, and the production cost can be reduced.

[0052] Embodiment 2: The difference between Embodiment 2 and Embodiment 1 is that the output end of the live line collection branch 101 includes three contacts.

[0053] Here, only the connection relationship between the input end of the live wire collection branch 101 and the live wire of the three-phase AC power, and the connection relationship between the output end of the live wire collection branch 101 and the negative feedback operation 20 are described when the output end of the live wire collection branch 101 includes three contacts. The remaining circuit components and connection relationships can refer to the relevant descriptions in Example 1 and will not be repeated here.

[0054] In the three-phase alternating current, the first phase live wire L1 is connected in series with the first relay K1 , the second phase live wire L2 is connected in series with the third relay K3 , and the third phase live wire L3 is connected in series with the fourth relay K4 .

[0055] The first contact of the input end of the live wire acquisition branch 101 is connected to the output side L1_OUT of the live wire contact point of the first relay K1, the second contact is connected to the output side L2_OUT of the live wire contact point of the third relay K3, and the third contact is connected to the output side L3_OUT of the live wire contact point of the fourth relay K4. The output end of the live wire acquisition branch 101 is connected to the inverting input end of the operational amplifier U1A.

[0056] In order to reduce the damage of the live high voltage alternating current to the subsequent circuit, as an optional implementation method, a plurality of high voltage sampling resistors for voltage division are connected in series between the first contact of the input end and the output end of the live wire acquisition branch 101; a plurality of high voltage sampling resistors for voltage division are connected in series between the second contact of the input end and the output end of the live wire acquisition branch 101; a plurality of high voltage sampling resistors for voltage division are connected in series between the third contact of the input end and the output end of the live wire acquisition branch 101.

[0057] In order to meet the requirements of safety distance, the following is an example in which a first contact and the output end are connected in series with a number of high-voltage sampling resistors for voltage division, namely the first resistor R1, the second resistor R2 and the third resistor R3. An example in which a second contact and the output end are connected in series with a number of high-voltage sampling resistors for voltage division, namely the tenth resistor R10, the eleventh resistor R11 and the twelfth resistor R12 is used for exemplary description; an example in which a third contact and the output end are connected in series with a number of high-voltage sampling resistors for voltage division, namely the thirteenth resistor R13, the fourteenth resistor R14 and the fifteenth resistor R15 is used for exemplary description.

[0058] Among them, the resistance values ​​of the tenth resistor R10, the eleventh resistor R11, the twelfth resistor R12, the thirteenth resistor R13, the fourteenth resistor R14 and the fifteenth resistor R15 can be selected according to the implementation situation, and the present invention does not specifically limit this; for the types of the tenth resistor R10, the eleventh resistor R11, the twelfth resistor R12, the thirteenth resistor R13, the fourteenth resistor R14 and the fifteenth resistor R15, the embodiments of the present invention will be exemplified by using a metal film or chip resistor with a rated voltage of 500 volts (V) or above.

[0059] In order to isolate the DC signal on the AC power, suppress surges, improve circuit insulation performance and save costs, as an optional implementation, a first high-voltage isolation capacitor C1 is connected in series between the first contact at the input end and the output end of the live wire collection branch 101; a third high-voltage isolation capacitor C3 is connected in series between the second contact at the input end and the output end of the live wire collection branch 101; and a fourth high-voltage isolation capacitor C4 is connected in series between the third contact at the input end and the output end of the live wire collection branch 101.

[0060] Among them, the capacitance of the third high-voltage isolation capacitor C3 and the fourth high-voltage isolation capacitor C4 can be selected according to the implementation situation, and the present invention does not make any special limitation on this; as for the types of the third high-voltage isolation capacitor C3 and the fourth high-voltage isolation capacitor C4, the embodiments of the present invention will be explained later by taking the use of ceramic capacitors with a withstand voltage of 500V or above as an example.

[0061] Among them, the present invention does not specifically limit the position between the third high-voltage isolation capacitor C3 and the high-voltage sampling resistor on the live wire, and the position relationship between the fourth high-voltage isolation capacitor C4 and the high-voltage sampling resistor on the live wire. An exemplary description is given by taking the third high-voltage isolation capacitor C3 connected in series between the second contact at the input end of the live wire acquisition branch 101 and the tenth resistor R10 as an example, and an exemplary description is given by taking the fourth high-voltage isolation capacitor C4 connected in series between the third contact at the input end of the live wire acquisition branch 101 and the thirteenth resistor R13 as an example.

[0062] The following explains Figure 3 The working principle of the relay sticking detection circuit is provided.

[0063] For those skilled in the art, after knowing the working principle of the relay adhesion detection circuit under single-phase AC, the working principle of the relay adhesion detection circuit under three-phase AC is easy to imagine and will not be repeated here.

[0064] The relay adhesion detection circuit provided in Example 2 of the present application can achieve the same beneficial effects as the relay adhesion detection circuit provided in the above-mentioned Example 1, which will not be repeated here.

[0065] An embodiment of a relay adhesion detection system: Figure 4 is a structural diagram of a relay adhesion detection system provided by an embodiment of the present invention, such as Figure 4 As shown, the relay adhesion detection system includes: a controller and the relay adhesion detection circuit in any of the aforementioned embodiments, and the controller is connected to the output end of the comparator.

[0066] Among them, the relay adhesion detection circuit includes an acquisition circuit 10, a negative feedback amplifier 20, a filtering and voltage stabilizing circuit 40 and a level conversion circuit 30. For the relay adhesion detection circuit, reference may be made to the aforementioned related descriptions, which will not be repeated here.

[0067] Here, only the function of the controller is described. The controller 40 is used to control the opening or closing of the live contact and the neutral contact, and to detect the signal waveform output by the comparator U2A in the level conversion circuit 30, so as to determine the working status of the relays K1 and K2.

[0068] Specifically, when relay K1 and relay K2 are in a closed state, and the controller 40 controls relay K1 and relay K2 to disconnect, if it is detected that the comparator U2A still outputs a square wave signal at this time, it means that relay K1 and relay K2 are not disconnected, and at this time, it is judged that relay K1 and relay K2 are stuck; if it is detected that the comparator U2A outputs a non-square wave signal at this time, it means that relay K1 and relay K2 are disconnected, and it is judged that no sticking occurs.

[0069] In order to protect the safety of electrical equipment and improve the insulation of the circuit, as an optional implementation, the controller 40 is also used to control all other relays to power off when it is determined that the relays connected in series on the live wire and the relays connected in series on the neutral wire are sticky.

[0070] In order to remind users to disconnect electrical equipment in time to protect users or remind maintenance personnel, as an optional implementation, the relay adhesion detection system also includes an alarm module 60 connected to the output end of the control module, which is used to alarm when the control module determines that the relay connected in series on the live wire and the relay connected in series on the neutral wire are stuck.

[0071] The alarm module 60 may be a sound alarm module, a light alarm module, or an alarm module with both sound and light, etc. It may be selected according to actual conditions, and the present invention does not make any special limitation on this.

[0072] The relay adhesion detection system provided by the embodiment of the present invention uses the acquisition circuit to collect the live wire voltage and the neutral wire voltage on the output side of the relay in the AC circuit to understand the current opening and closing state of the relay, and uses the negative feedback amplifier to reduce the live wire voltage and the neutral wire voltage, which can ensure the safety of the subsequent circuit; the signal output by the negative feedback amplifier is converted by the level conversion circuit, and a smoother and more stable detection signal can be obtained. When the live wire contact and the neutral wire contact are originally in a closed state, the comparator will output a square wave signal. At this time, if the live wire contact and the neutral wire contact are disconnected, the comparator continues to output a square wave signal, indicating that the live wire contact and the neutral wire contact are not disconnected, and the relay is adhered. The relay adhesion detection circuit has a simple structure and a simple judgment logic, so the complexity of the relay adhesion detection circuit detection can be reduced and the production cost can be reduced. In addition, because the controller module and the alarm module are added, the safety can be improved.

Claims

1. A relay adhesion detection circuit, characterized in that: Including acquisition circuit, negative feedback amplifier and level conversion circuit; The acquisition circuit includes a live line acquisition branch and a neutral line acquisition branch; the level conversion circuit includes a comparator; The input end of the live wire acquisition branch is used to connect to the output side of the live wire contact of the relay connected in series on the live wire; the input end of the neutral wire acquisition branch is used to connect to the output side of the neutral wire contact of the relay connected in series on the neutral wire; the output end of the live wire acquisition branch and the output end of the neutral wire acquisition branch are respectively connected to the two input ends of the negative feedback amplifier; the in-phase input end of the negative feedback amplifier is also connected to the first reference signal; one input end of the comparator is connected to the output end of the negative feedback amplifier, and the other input end is connected to the second reference signal; When the live wire contact and the neutral wire contact are disconnected, but it is detected that the comparator output is a square wave signal, it is determined that the relay connected in series on the live wire and the relay connected in series on the neutral wire are stuck.

2. The relay adhesion detection circuit according to claim 1, characterized in that: The input end of the live wire collection branch is used to connect to the output side of the live wire contact of the relay connected in series on the live wire, including: when the live wire is a three-phase live wire, the input end of the live wire collection branch includes three contacts; Each of the three-phase live wires is connected in series with a relay; Each contact is connected to the output side of a relay's live contact.

3. The relay adhesion detection circuit according to claim 1 or 2, characterized in that: A plurality of high-voltage sampling resistors for voltage division are connected in series on both the live line acquisition branch and the neutral line acquisition branch.

4. The relay adhesion detection circuit according to claim 3, characterized in that: The live line acquisition branch and the neutral line acquisition branch are both connected in series with high-voltage isolation capacitors for isolating DC components.

5. The relay adhesion detection circuit according to claim 1, characterized in that: Also includes: A current limiting resistor is connected in series between the non-inverting input terminal of the negative feedback operational amplifier and the first reference signal and is used for current limiting.

6. The relay adhesion detection circuit according to claim 1, characterized in that: Also includes: A filtering and voltage stabilizing circuit is connected in series between the output end of the negative feedback operational amplifier and the input end of the level conversion circuit, and is used for filtering and stabilizing the signal output by the negative feedback operational amplifier.

7. The relay adhesion detection circuit according to claim 6, characterized in that: The filtering and voltage stabilizing circuit comprises an RC filter.

8. A relay adhesion detection system, characterized in that: include: A controller, a relay adhesion detection circuit as described in any one of claims 1 to 7 above; The controller is connected to the output end of the comparator; when the controller controls the live wire contact and the neutral wire contact to be disconnected, but detects that the comparator output is a square wave signal, it is determined that the relay connected in series on the live wire and the relay connected in series on the neutral wire are stuck.

9. The relay adhesion detection system according to claim 8, characterized in that: When the controller determines that the relays connected in series on the live wire and the relays connected in series on the neutral wire are stuck, the controller controls all other relays to be powered off.

10. The relay adhesion detection system according to claim 8 or 9, characterized in that: Also includes: An alarm module connected to the output end of the controller is used to alarm when the control module determines that the relay connected in series on the live wire and the relay connected in series on the neutral wire are adhered.

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