An AC solid-state relay with state detection function

Abstract

The present invention relates to an AC solid-state relay with a state detection function, which belongs to the technical field of AC solid-state relays and includes an input control module and an output detection module. The input control module is connected to the output detection module and is responsible for controlling the operation of the switching device in the output detection module. The output detection module is connected to the load and is responsible for detecting and supplying power to the load under the control of the input control module. The AC solid-state relay with a state detection function provided by the present invention realizes fault detection of thyristor short circuit, external load disconnection and no power supply at the power supply network end by setting the output detection module. Since the overall circuit structure is simple, the volume of the entire solid-state relay is reduced. In addition, since the output detection module leads to a first test terminal and a second test terminal, it can be conveniently connected to an external MCU, facilitating remote monitoring.

Description

Technical Field

[0001] The present invention belongs to the technical field of AC solid-state relays, and in particular relates to an AC solid-state relay with a state detection function. Background Art

[0002] With the rapid development of railway technology, railway signal control equipment is gradually moving towards electronicization, intelligence, and miniaturization. Solid-state relays are increasingly replacing traditional mechanical relays in railway signaling equipment. Solid-state relays are typically composed of electronic components such as thyristors and optocouplers. During use, they can experience faults such as thyristor short circuits, external load disconnections, or network power outages. Failure to promptly address these faults can pose a significant safety hazard to the safe and reliable operation of the entire equipment. Therefore, monitoring the status of solid-state relays and loads to quickly analyze and address any faults has become a key development direction for solid-state relays.

[0003] Currently, solid-state relays with status monitoring functions determine their status by collecting valid information such as the input and output current and voltage of the solid-state relay. This requires complex circuitry, resulting in large size and poor stability. Furthermore, some solid-state relays use indicator lights to display relay status, but this method cannot be connected to an external MCU and cannot achieve remote monitoring. Summary of the Invention

[0004] In view of the above-mentioned defects in the prior art, the present invention proposes an AC solid-state relay with a state detection function.

[0005] The technical solution of the invention is as follows:

[0006] An AC solid-state relay with a state detection function includes an input control module and an output detection module. The input control module is connected to the output detection module and is responsible for controlling the operation of the switching device in the output detection module. The output detection module is connected to the load and is responsible for supplying power to the load under the control of the input control module.

[0007] Furthermore, the input control module includes a resistor R1 and a bidirectional optocoupler U1 , the voltage input terminal ctrU is connected to the input terminal of the bidirectional optocoupler U1 through the resistor R1 , and the output terminal of the bidirectional optocoupler U1 is connected to the output detection module.

[0008] Furthermore, the output detection module includes resistors R2, R3, R4, R5, a rectifier bridge U3, an optocoupler U2 and a bidirectional thyristor Q1; the input end of the optocoupler U2 is connected to the detection voltage input end testU through the resistor R4, and the output end is connected to the DC output end of the rectifier bridge U3; the output end out1 is connected to the output end out3 of the bidirectional optocoupler U1 through the resistor R2, the output end out2 is connected to an AC input end of the rectifier bridge U1 through the resistor R5, and the output end out4 of the bidirectional optocoupler U1 is connected to another AC input end of the rectifier bridge U3; the T1 and T2 ends of the bidirectional thyristor Q1 are connected to the output end out1 and the output end out2 respectively, the G end of the bidirectional thyristor Q1 is connected to the end of the resistor R5 away from the output end out2, and the negative pole of the DC output end of the rectifier bridge U3 is connected to the output end out3 of the bidirectional optocoupler U1 through the resistor R3.

[0009] Furthermore, the input end of the bidirectional optocoupler U1 connected to the resistor R1 is connected to the first test end test1 , and the output end of the optocoupler U2 connected to the resistor R4 is connected to the second test end test2 .

[0010] Compared with the prior art, the present invention has the following advantages:

[0011] The present invention provides an AC solid-state relay with a status detection function. By providing an output detection module, it detects faults such as thyristor short circuits, external load disconnections, and power failures at the power supply network. Due to its simple overall circuit structure, the size of the solid-state relay is reduced. Furthermore, since the output detection module provides first and second test terminals, it can be easily connected to an external MCU, facilitating remote monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a circuit schematic diagram of an AC solid-state relay with a state detection function according to the present invention;

[0013] Figure 2 The timing diagram is used to analyze the three fault conditions: thyristor short circuit, external load disconnection, and no power supply at the power supply network end. DETAILED DESCRIPTION

[0014] The technical solution of the present invention is described in detail below with reference to the accompanying drawings. In the description of this application, it should be understood that, unless otherwise explicitly stated, the terms "install," "place," "set," "connect," "fix," etc. should be understood in a broad sense and may be understood as meaning a fixed connection or a detachable connection, etc., depending on the specific technical solution in which they are located. A person of ordinary skill in the art can understand the specific meanings of the above terms based on the specific circumstances involved in the technical solution.

[0015] Figure 1An AC solid-state relay with a state detection function shown in the figure includes an input control module and an output detection module. The input control module is connected to the output detection module and is responsible for controlling the operation of the switching device in the output detection module. The output detection module is connected to the load and is responsible for supplying power to the load under the control of the input control module.

[0016] In the above technical solution, the input control module includes a resistor R1 and a bidirectional optocoupler U1. The voltage input terminal ctrU includes two terminals, each connected to the two input pins of the bidirectional optocoupler U1. A current-limiting resistor R1 is provided at the point where the voltage input terminal ctrU connects to the cathode of the photodiode in the bidirectional optocoupler U1. A test terminal, test1, is connected to the pin corresponding to the cathode of the photodiode in the bidirectional optocoupler U1. The two output terminals, out3 and out4, of the bidirectional optocoupler U1 are connected to corresponding positions in the output detection module.

[0017] The output detection module includes resistors R2, R3, R4, and R5, a rectifier bridge U3, a unidirectional optocoupler U2, and a bidirectional thyristor Q1. The two input terminals of the optocoupler U2 are respectively connected to the two terminals of the detection voltage input terminal testU. A current-limiting resistor R4 is provided at the connection point between the detection voltage input terminal testU and the emitter of the phototransistor in the optocoupler U2. A test terminal is connected to the pin corresponding to the emitter of the phototransistor of the optocoupler U2 as a second test terminal test2. The output terminal of the optocoupler U2 is connected to the DC output terminal of the rectifier bridge U3. In other words, the two output terminals of the optocoupler U2 are respectively connected to the anodes of the common anode diodes D3 and D4 and the cathodes of the common cathode diodes D1 and D2. Output terminal out1 is connected to output terminal out3 of bidirectional optocoupler U1 via resistor R2. Output terminal out2 is connected to one AC input terminal of rectifier bridge U1 via resistor R5. That is, output terminal out2 is connected to the junction of diodes D2 and D3 in rectifier bridge U3 via resistor R5. Output terminal out4 of bidirectional optocoupler U1 is connected to the other AC input terminal of rectifier bridge U3. That is, output terminal out4 of bidirectional optocoupler U1 is connected to the junction of diodes D1 and D4 in rectifier bridge U3. Terminals T1 and T2 of bidirectional thyristor Q1 are connected to output terminals out1 and out2, respectively. Terminal G of bidirectional thyristor Q1 is connected to the end of resistor R5 away from output terminal out2. The negative terminal of the DC output terminal of rectifier bridge U3, that is, the anode of common-anode diodes D3 and D4 in rectifier bridge U3, is connected to output terminal out3 of bidirectional optocoupler U1 via resistor R3.

[0018] Below through Figure 2 The operation and fault detection process of solid-state relays are introduced.

[0019] like Figure 2 As shown, taking the connection of resistive load as an example, Figure 2The first curve shows the relationship between the control voltage input at the voltage input terminal ctrU and time. A high level indicates the presence of input voltage. The second curve shows the relationship between the power supply network and time, expressed using an AC signal. The third curve shows the relationship between the load current and time. The fourth and fifth curves respectively show the high and low levels of the first test terminal test1 and the second test terminal test2. Segment 1 of the second curve represents a power supply network disconnection fault, in which the power supply network voltage is zero. Segment 2 of the third curve represents a load short-circuit fault, in which the load current is zero. Segment 3 of the first curve represents a bidirectional thyristor short-circuit fault. Simply by monitoring the high and low levels of the outputs of the first test terminal test1 and the second test terminal test2 in real time, it is possible to quickly detect whether the solid-state relay has experienced any of the three fault conditions described above.

[0020] During normal operation, i.e., when there are no faults, the load and solid-state relay are in good condition. Without a control voltage input at the voltage input terminal ctrU, the output terminal of the optocoupler U1 is non-conductive and disconnected, resulting in no trigger current. The bidirectional thyristor Q1 is disconnected, and the power supply network is unable to supply power to the load, causing the load to not operate. In this case, the power supply network provides a trigger current to the optocoupler U2 through the resistor R3 and the rectifier bridge U3. This current is only sufficient to drive the optocoupler U2 but not the bidirectional thyristor Q1. At this point, the optocoupler U2 is conductive, and the second test terminal test2 is equivalent to being connected to the detection voltage input terminal testU, generating a high level at the second test terminal test2.

[0021] When a control voltage is applied to the voltage input terminal ctrU, the output terminals out3 and out4 of the bidirectional optocoupler U1 are in the conductive state. This generates sufficient current to trigger the bidirectional thyristor Q1, turning it on and enabling the power supply network to supply power to the load, which begins operating. In this case, the current flowing through the rectifier bridge U3 is sufficient to drive the optocoupler U2 into conduction, and the second test terminal test2 pin will still generate a high level. Therefore, regardless of whether a control voltage is applied to the voltage input terminal ctrU, as long as the solid-state relay is operating normally, the second test terminal test2 pin will output a high level.

[0022] When there is no power supply network, the load is disconnected and there is no control voltage input to the voltage input terminal ctrU, no current flows through the resistor R3 and the optocoupler U2 cannot be driven. Therefore, the second test terminal test2 pin will output a low level.

[0023] When the triac Q1 shorts, the entire solid-state relay is in an uncontrolled state. Regardless of whether there is a control voltage at the voltage input terminal ctrU, the triac cannot be controlled. At this time, resistor R3 is short-circuited by the triac and cannot provide trigger current for the optocoupler U2. Therefore, the second test terminal test2 pin is low. Therefore, by detecting the high and low levels of the second test terminal test2 pin, it is possible to determine whether the solid-state relay has a load disconnection, a power supply disconnection, or a triac disconnection fault.

Claims

1. An AC solid-state relay with a state detection function, characterized in that: It includes an input control module and an output detection module; the input control module is connected to the output detection module and is responsible for controlling the operation of the switch device in the output detection module; The output detection module is connected to the load and is responsible for supplying power to the load under the control of the input control module; The input control module includes a resistor R1 and a bidirectional optocoupler U1, the voltage input terminal ctrU is connected to the input terminal of the bidirectional optocoupler U1 through the resistor R1, and the output terminal of the bidirectional optocoupler U1 is connected to the output detection module; The output detection module includes resistors R2, R3, R4, R5, a rectifier bridge U3, an optocoupler U2 and a bidirectional thyristor Q1; the input end of the optocoupler U2 is connected to the detection voltage input end testU through the resistor R4, and the output end is connected to the DC output end of the rectifier bridge U3; the output end out1 is connected to the output end out3 of the bidirectional optocoupler U1 through the resistor R2, the output end out2 is connected to an AC input end of the rectifier bridge U1 through the resistor R5, and the output end out4 of the bidirectional optocoupler U1 is connected to the other AC input end of the rectifier bridge U3; The T1 and T2 terminals of the bidirectional thyristor Q1 are connected to the output terminal out1 and the output terminal out2 respectively, the G terminal of the bidirectional thyristor Q1 is connected to the end of the resistor R5 away from the output terminal out2, and the negative electrode of the DC output terminal of the rectifier bridge U3 is connected to the output terminal out3 of the bidirectional optocoupler U1 through the resistor R3.

2. The AC solid-state relay with state detection function according to claim 1, characterized in that: The input end of the bidirectional optical coupler U1 connected to the resistor R1 is connected to the first test end test1 , and the output end of the optical coupler U2 connected to the resistor R4 is connected to the second test end test2 .

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