Safety control circuit and device

Abstract

The utility model relates to a safety control circuit and equipment. The safety control circuit is used for being connected between a power supply module and a load, the safety control circuit comprises a power supply diagnosis circuit, a switching circuit and a bypass circuit, the first input end of the power supply diagnosis circuit is connected with the power supply module, and the second input end of the power supply diagnosis circuit is connected with the load; the switching circuit is connected with the power supply module and the load, and the switching circuit is also connected with the output end of the power supply diagnosis circuit. The bypass circuit is respectively connected with the power supply module and the switching circuit; wherein the bypass circuit is used for controlling the switching circuit to conduct a power supply path between the power supply module and the load in the power-on process of the load, and the bypass circuit is further used for being in a disconnected state after the load is powered on. According to the technical scheme provided by the invention, power supply diagnosis and safe automatic turn-off of the system can be realized, and normal power-on of the system can also be ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of functional safety technology, in particular to a safety control circuit and device. BACKGROUND

[0002] Functional safety products need to diagnose the power supply of modules in the system, and the fault diagnosis processing requirements of functional safety products are different according to the safety level of the system.

[0003] For example, the safety level of safety PLC (Programmable Logic Controller) and safety instrument system (SIS) in the industrial field is SIL (Safety Integrity Levels) 3, the safety level of ground signal equipment and vehicle-mounted signal equipment in the rail transit field is SIL 4, and the safety level of nuclear power products is SIL 4. The power supply diagnosis coverage requirement of these products is greater than 90%, and the functional safety products need to monitor the power supply of these products. When the power supply exceeds the normal specification, the safety mechanism is triggered to ensure that the system enters a safe state, so as to meet the power supply diagnosis coverage requirement.

[0004] However, during the application of functional safety products, the system often cannot be normally powered on. CONTENT OF THE INVENTION

[0005] Therefore, based on this, the embodiments of the present application provide a safety control circuit and device, which can realize power supply diagnosis and safety automatic shutdown of the system, and also ensure the normal power-on of the system.

[0006] In a first aspect, the present application provides a safety control circuit. The safety control circuit is used to be connected between a power supply module and a load, and the safety control circuit comprises:

[0007] a power supply diagnosis circuit, a first input end of the power supply diagnosis circuit being connected with the power supply module, and a second input end of the power supply diagnosis circuit being connected with the load;

[0008] a switch circuit, the switch circuit being connected with the power supply module and the load respectively, and the switch circuit being further connected with an output end of the power supply diagnosis circuit;

[0009] a bypass circuit, the bypass circuit being connected with the power supply module and the switch circuit respectively;

[0010] The bypass circuit is used for controlling the switch circuit to turn on the power supply path between the power supply module and the load during the load power-on process, and the bypass circuit is used for being in an off state after the load is powered on.

[0011] In one of the embodiments, the switch circuit comprises:

[0012] The first switch tube has a first end connected with an output end of the power supply diagnosis circuit, and a second end grounded;

[0013] The first resistance has a first end connected with a third end of the first switch tube, and the bypass circuit is connected between the first end of the first resistance and the third end of the first switch tube;

[0014] The second switch tube has a first end connected with a second end of the first resistance, a second end connected with the power supply module, and a third end connected with the load;

[0015] The second resistance has a first end connected with the first end of the second switch tube, and a second end connected with the second end of the second switch tube.

[0016] In one of the embodiments, the bypass circuit comprises:

[0017] The first capacitor has a first end connected with the power supply module;

[0018] The third resistance has a first end connected with a second end of the first capacitor;

[0019] The third switch tube has a first end connected with a second end of the third resistance, a second end grounded, and a third end connected between the first end of the first resistance and the third end of the first switch tube.

[0020] In one of the embodiments, the safety control circuit further comprises:

[0021] The second capacitor has a first end connected between the first end of the first resistance and the third end of the first switch tube, and a second end grounded.

[0022] In one of the embodiments, the bypass circuit further comprises:

[0023] The voltage stabilizing module has a first end connected with a first input end of the power supply diagnosis circuit, and a second end grounded.

[0024] In one embodiment, the power supply diagnostic circuit comprises a plurality of second inputs, each of the second inputs being connected to a respective power input of the load.

[0025] In one embodiment, the power supply diagnostic circuit comprises an over-voltage diagnostic circuit and / or an under-voltage diagnostic circuit; wherein,

[0026] the first input of the over-voltage diagnostic circuit is connected to the power supply module, the second input of the over-voltage diagnostic circuit is connected to the load, and the output of the over-voltage diagnostic circuit is connected to the switching circuit.

[0027] the first input of the under-voltage diagnostic circuit is connected to the power supply module, the second input of the under-voltage diagnostic circuit is connected to the load, and the output of the under-voltage diagnostic circuit is connected to the switching circuit.

[0028] In one embodiment, the power supply diagnostic circuit comprises a comparator and a reference power supply module connected to the comparator; wherein,

[0029] the first input of the comparator is connected to the power supply module, the second input of the comparator is connected to the load, and the output of the comparator is connected to the switching circuit.

[0030] In one embodiment, the number of safety control circuits is more than one, and the plurality of safety control circuits are connected in series between the power supply module and the load.

[0031] In a second aspect, the present application provides a device. The device comprises a power supply module, a load, and a safety control circuit as described in any one of the first aspect above, the safety control circuit being connected between the power supply module and the load.

[0032] The above safety control circuit and device, the safety control circuit is used for connecting between the power module and the load, the safety control circuit includes a power supply diagnosis circuit, a switch circuit and a bypass circuit, the first input end of the power supply diagnosis circuit is connected with the power module, the second input end of the power supply diagnosis circuit is connected with the load, the switch circuit is connected with the power module and the load respectively, the switch circuit is also connected with the output end of the power supply diagnosis circuit, the bypass circuit is connected with the power module and the switch circuit respectively, the bypass circuit is used for controlling the switch circuit to turn on the power supply path between the power module and the load during the load power-on process, and the bypass circuit is also used for being in the off state after the load power-on, so that, through the design of the bypass circuit, the switch circuit can be controlled to turn on the power supply path between the power module and the load during the load power-on process, so as to ensure the smooth power-on of the system, and avoid the problem that the system cannot be started due to the functional safety product cutting off the power supply when the input voltage provided by the power module is in an under-voltage state during the system power-on in the related art; in addition, after the load power-on, the bypass circuit switches to the off state, at this time, the power supply diagnosis and the safe automatic shutdown after the power-on are realized by the power supply diagnosis circuit, therefore, the power supply diagnosis and the safe automatic shutdown of the system can be realized, and the normal power-on of the system can also be ensured. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0034] Figure 1 A schematic diagram of a safety control circuit provided by an embodiment of the present application;

[0035] Figure 2 A schematic diagram of another safety control circuit provided by an embodiment of the present application;

[0036] Figure 3 A schematic diagram of another safety control circuit provided by an embodiment of the present application;

[0037] Figure 4 A schematic diagram of another safety control circuit provided by an embodiment of the present application;

[0038] Figure 5 A schematic diagram of another safety control circuit provided by an embodiment of the present application;

[0039] Figure 6 A working logic relationship schematic diagram of a power supply diagnosis circuit and a load provided by an embodiment of the present application.

[0040] Reference Signs List:

[0041] Safety control circuit - 10; power supply diagnosis circuit - 101; switching circuit - 102; bypass circuit - 103; power supply module - 20; load - 30. DETAILED DESCRIPTION

[0042] For the purpose of promoting an understanding of the present application, the present application will be described with reference to the drawings. Embodiments of the present application are illustrated in the drawings. However, the present application can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0044] It should be understood that the terms "first", "second" and so on as used herein can be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, a first resistor can be referred to as a second resistor without departing from the scope of the present application, and similarly, a second resistor can be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0045] It should be understood that "connection" in the following embodiments means that the circuits, modules, units, etc. connected to each other have electrical signal or data transmission.

[0046] It should be understood that "at least one" means one or more, and "multiple" means two or more. "At least part of an element" means part or all of the element.

[0047] As used herein, the singular forms "a", "an" and "the" can include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "comprise / comprising" or "have / having" specifies the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but does not exclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in the specification includes any and all combinations of the related listed items.

[0048] The functional safety product can perform fault diagnosis on the power module in the system, and different safety levels of the load in the system require different fault diagnosis processing of the functional safety product.

[0049] For example, the safety level of the safety PLC and the safety instrument system in the industrial field is SIL3, the safety level of the ground signal equipment and the vehicle-mounted signal equipment in the rail transit field is SIL4, and the safety level of the nuclear power product is SIL4. The power diagnosis coverage requirement of these products is greater than 90%, and the functional safety product needs to monitor the power module of these products, trigger the safety mechanism when the power module exceeds the normal specification, and ensure that the system enters a safe state to meet the power diagnosis coverage requirement.

[0050] The functional safety product can be used to monitor the power module of the load in the system. When the load is normally running, if overvoltage or undervoltage fault occurs in the power module, the input power module is cut off, the load is powered off, and the system enters a safe state.

[0051] However, when the system is powered on, the functional safety product will cut off the power module because the input voltage provided by the power module is in an undervoltage state, which will cause the load to fail to start up.

[0052] Therefore, the embodiment of the present application provides a safety control circuit and a device, which can ensure normal power-on of the system and also realize power diagnosis and automatic safety shutdown of the system after the system is powered on.

[0053] In the following, the technical solutions and beneficial effects provided by the embodiments of the present application are exemplarily introduced in combination with the drawings.

[0054] Please refer to Figure 1 , a safety control circuit 10 is provided, which is connected between a power module 20 and a load 30.

[0055] In the embodiment of the present application, the power module 20 can be a power circuit. Optionally, the power circuit can include a DC / DC (direct current / direct current converter) circuit, the input end of the DC / DC circuit is connected with an external power supply, and the output end of the DC / DC circuit is connected with the safety control circuit 10. Optionally, the power circuit can include a DC / DC circuit and a hot plug circuit, which is connected between the external power supply and the DC / DC circuit. Optionally, the power circuit can further include a power supply, and the embodiment of the power module 20 is not limited here, and the power module 20 is used to supply power to the safety control circuit 10 and the load 30.

[0056] The load 30 can be a PLC as mentioned above, or it can be a CPU (Central Processing Unit), MUC (Micro Controller Unit), etc.

[0057] The number of loads 30 can be one, for example... Figure 1 As shown, in some possible implementations, the number of loads 30 can also be multiple, for example, see [link to relevant documentation]. Figure 2 There are two loads 30, which are connected in parallel to the safety control circuit 10.

[0058] Please continue reading Figure 1 or Figure 2 In this embodiment of the application, the safety control circuit 10 includes a power diagnostic circuit 101, a switching circuit 102, and a bypass circuit 103.

[0059] For example, the power diagnostic circuit 101 may be an integrated chip with overvoltage and undervoltage monitoring functions.

[0060] The first input terminal of the power diagnostic circuit 101 is connected to the power module 20, which supplies power to the power diagnostic circuit 101. The second input terminal of the power diagnostic circuit 101 is connected to the load 30, allowing the power diagnostic circuit 101 to detect the input voltage of the load 30. The output terminal of the power diagnostic circuit 101 is connected to the switch circuit 102. After the load 30 is powered on and starts working normally, the power diagnostic circuit 101 can control the switch circuit 102 to turn on or off based on the detected input voltage of the load 30. For example, if the power diagnostic circuit 101 detects that the input voltage of the load 30 is too high or too low (i.e., an overvoltage or undervoltage fault occurs), the power diagnostic circuit 101 outputs a low-level signal, and the switch circuit 102 turns off to cut off the power supply path between the power module 20 and the load 30, ensuring system safety.

[0061] In this embodiment, the switch circuit 102 is connected to the power module 20 and the load 30 respectively. The switch circuit 102 is also connected to the output terminal of the power diagnostic circuit 101. As described above, the level signal output by the output terminal of the power diagnostic circuit 101 can control the switching circuit 102 to turn on and off. The switch circuit 102 may include a switching transistor. The circuit structure of the switch circuit 102 will be described in the following embodiments.

[0062] In the embodiment of the present application, the safety control circuit 10 further comprises a bypass circuit 103, which is connected with the power module 20 and the switch circuit 102 respectively, wherein the bypass circuit 103 is configured to control the switch circuit 102 to turn on the power supply path between the power module 20 and the load 30 during the power-on process of the load 30.

[0063] It can be understood that, when the load 30 is powered on, the input voltage of the load 30 is small, and without the bypass circuit 103, the power supply diagnosis circuit 101 will misjudge that an under-voltage fault occurs, and control the switch circuit 102 to be turned off (for example, output a low-level signal) to thereby cut off the power supply path between the power module 20 and the load 30, which will result in that the load 30 cannot be powered on smoothly and affect the normal work of the load 30.

[0064] In the embodiment of the present application, by arranging the bypass circuit 103, the bypass circuit 103 can control the switch circuit 102 to turn on the power supply path between the power module 20 and the load 30 during the power-on process of the load 30, so that the power module 20 normally supplies power to the load 30, thereby ensuring that the system is powered on smoothly.

[0065] The bypass circuit 103 is further configured to be in an off state after the load 30 is powered on. After the load 30 is powered on, the bypass circuit 103 is switched to the off state, and at this time, the power supply diagnosis and the safety automatic shutdown after power-on are realized by the power supply diagnosis circuit 101. For example, when the input voltage of the load 30 detected by the power supply diagnosis circuit 101 is too large or too small (i.e., an over-voltage or under-voltage fault occurs), the power supply diagnosis circuit 101 outputs a low-level signal, and the switch circuit 102 is turned off, thereby cutting off the power supply path between the power module 20 and the load 30, and ensuring the safety of the system. Therefore, the embodiment of the present application can realize the power supply diagnosis and the safety automatic shutdown of the system, and also can ensure the normal power-on of the system.

[0066] In one embodiment, in Figure 1 or Figure 2 on the basis of the embodiment shown in Figure 2 , the embodiment shown in

[0067] Referring to Figure 3 , the switch circuit 102 can comprise Figure 3 a first switch tube (Q1) shown in Figure 3 , a first resistor (R1) shown in Figure 3 , a second switch tube (Q2) shown in Figure 3 , and a second resistor (R2) shown in Figure 3The R2) is shown. In addition, the power supply diagnosis circuit 101 can also be connected to the power module 20 in parallel through the current limiting resistor R5, and the input current of the power supply diagnosis circuit 101 is limited through the current limiting resistor R5, which is beneficial to improve the safety of the power supply diagnosis circuit 101.

[0068] The first end of the first switch tube is connected with the output end of the power supply diagnosis circuit 101, and the second end of the first switch tube is grounded. The first end of the first resistor is connected with the third end of the first switch tube, and the bypass circuit 103 is connected between the first end of the first resistor and the third end of the first switch tube.

[0069] Exemplarily, the first switch tube can be an NPN type triode, and the base B of the first switch tube is connected with the output end of the power supply diagnosis circuit 101, and the emitter E of the first switch tube is grounded. The first end of the first resistor is connected with the collector C of the first switch tube, and the bypass circuit 103 is connected between the first end of the first resistor and the collector C of the first switch tube.

[0070] The first end of the second switch tube is connected with the second end of the first resistor, the second end of the second switch tube is connected with the power module 20, and the third end of the second switch tube is connected with the load 30. Exemplarily, the second switch tube can be a P-type MOS tube, the gate of the second switch tube is connected with the second end of the first resistor, the source of the second switch tube is connected with the power module 20, and the drain of the second switch tube is connected with the load 30.

[0071] The first end of the second resistor is connected with the first end of the second switch tube (the gate of the second switch tube), and the second end of the second resistor is connected with the second end of the second switch tube (the source of the second switch tube).

[0072] Optionally, the switch circuit 102 can further include Figure 3 The resistor R4 and the capacitor C2 shown can filter the input signal of the first switch tube, so as to avoid the false triggering of the first switch tube.

[0073] In this embodiment of the application, during the system power-on process, i.e. when the load 30 is powered on, the power diagnostic circuit 101 is powered on first and starts working. In order to prevent the first and second switching transistors from being constantly disconnected and the load 30 from being unable to be powered on because the power diagnostic circuit 101 monitors the load 30 as being in an undervoltage state and the output terminal of the power diagnostic circuit 101 continuously outputs a low-level signal, the bypass circuit 103 is set up. One end of the bypass circuit 103 is connected to the power module 20, and the other end of the bypass circuit 103 is connected between the first end of the first resistor and the third end of the first switching transistor. In this way, when the load 30 is powered on, the bypass circuit 103 can bypass the first switching transistor. At this time, the second switching transistor is turned on, and the load 30 is successfully powered on, thereby ensuring that the system is powered on smoothly.

[0074] After the load 30 is successfully powered on, the bypass circuit 103 is disconnected. The power diagnostic circuit 101 monitors that the input voltage of the load 30 is normal. At this time, the output terminal of the power diagnostic circuit 101 outputs a high-level signal, the first switching transistor is turned on, and the second switching transistor can also remain on. The load 30 works normally. The power diagnostic circuit 101 continues to perform power diagnostics on the system and automatically shuts down the system in case of undervoltage or overvoltage faults to ensure the safety of the system.

[0075] The circuit structure of the switch circuit 102 has been described above as an example. The circuit structure of the bypass circuit 103 will be described below as an example.

[0076] In one embodiment, please see [link to previous article]. Figure 3 The bypass circuit 103 includes a first capacitor ( Figure 3 C1 shown), the third resistor ( Figure 3 R3 (shown) and the third switch ( Figure 3 Q3 shown).

[0077] The first terminal of the first capacitor is connected to the power module 20, and the first terminal of the third resistor is connected to the second terminal of the first capacitor.

[0078] The first terminal of the third switching transistor is connected to the second terminal of the third resistor, and the second terminal of the third switching transistor is grounded. The third terminal of the third switching transistor is connected between the first terminal of the first resistor and the third terminal of the first switching transistor. For example, the third switching transistor can be an NPN transistor, in which case the base B of the third switching transistor is connected to the second terminal of the third resistor, the emitter E of the third switching transistor is grounded, and the collector C of the third switching transistor is connected between the first terminal of the first resistor and the collector C of the first switching transistor.

[0079] When the load 30 is powered on, the power supply module 20 charges the first capacitor, and due to the characteristic that the voltage of the capacitor cannot be abruptly changed, when the load 30 is powered on, the first capacitor is equivalent to a short circuit, at this time, the third switch tube is turned on, the third switch tube bypasses the first switch tube, so that the second switch tube is turned on, and the load 30 is successfully powered on.

[0080] After the load 30 is successfully powered on, the power supply diagnosis circuit 101 detects that the input voltage of the load 30 is normal, and the output end of the power supply diagnosis circuit 101 outputs a high-level signal, so that the first switch tube is turned on, so that the second switch tube can remain in the on state, and the load 30 normally works. After the first capacitor is fully charged, the bypass circuit 103 is disconnected, the third switch tube is disconnected, the power supply diagnosis circuit 101 continues to perform power supply diagnosis of the system, and when there is an under-voltage or over-voltage fault, the first switch tube is turned off by outputting a low-level signal, and then the second switch tube is turned off, to ensure the safety of the system.

[0081] The bypass circuit 103 can further include a discharge resistor (such as Figure 3 The first end of the discharge resistor is connected with the first end of the first capacitor, and the second end of the discharge resistor is grounded. By setting the discharge resistor, the first capacitor can be discharged after being fully charged, so that the bypass circuit 103 can be normally used in the next power-on process.

[0082] In the embodiment, by means of the bypass circuit 103, the problem of under-voltage of the load 30 during power-on is ingeniously solved, the circuit structure is simple, the safety control circuit 10 of the embodiment is built by using separate components, which is conducive to reducing the overall hardware cost and saving the layout resources of the circuit board.

[0083] In one embodiment, on the basis of the embodiment shown in Figure 4 Optionally, the bypass circuit 103 can further include a filter module, the first end of the filter module is connected with the first end of the third switch tube, and the second end of the filter module is grounded.

[0084] As shown in Figure 4 The filter module can include a resistor R8 and a capacitor C3 as shown in Figure 4 The filter module can filter the input signal of the third switch tube to avoid mis-triggering of the third switch tube, and improve the reliability of the safety control of the embodiment.

[0085] Optionally, the bypass circuit 103 further includes a voltage stabilizing module, the first end of the voltage stabilizing module is connected with the first input end of the power supply diagnosis circuit 101, and the second end of the voltage stabilizing module is grounded.

[0086] As shown in Figure 4 The voltage stabilizing module can be Figure 4The voltage stabilizing tube Z1 shown can stabilize the input voltage provided by the power supply module 20 after the front-end power supply module 20 fails, so that the input voltage cannot exceed the upper limit of the working voltage of the power supply diagnosis circuit 101, avoiding damage to the power supply diagnosis circuit 101 and improving the working reliability of the power supply diagnosis circuit 101.

[0087] Optionally, the safety control circuit 10 further comprises a second capacitor, a first end of the second capacitor being connected between the first end of the first resistor and the third end of the first switch tube, and a second end of the second capacitor being grounded. Figure 4 As shown, the second capacitor can be Figure 3 The capacitor C4 shown.

[0088] After the load 30 is successfully powered on, when the input voltage of the load 30 is disturbed at a certain time, it may cause the input voltage to exceed the voltage during normal working of the load 30, at this time, the power supply diagnosis circuit 101 triggers the overvoltage protection, the output end of the power supply diagnosis circuit 101 outputs a low-level signal, the first switch tube is turned off, the second capacitor is in a charging state, the second capacitor, the first resistor and the second resistor can form a loop, and a voltage difference exists between the two ends of the second resistor, at this time, the second switch tube can be normally turned on, and the load 30 works normally; when the disturbance disappears, the input voltage of the load 30 returns to normal, the power supply diagnosis circuit 101 outputs a high-level signal, the first switch tube is turned on, and the second switch tube is also normally turned on, and the load 30 works normally, so that the false cut-off of the power supply module 20 caused by the interference signal can be avoided.

[0089] It should be noted that the charging time of the second capacitor can be regarded as the "tolerance time" of the disturbance, or called the shutdown response time, when the disturbance does not disappear after exceeding the tolerance time, it is indicated that an overvoltage or undervoltage fault occurs, and the second capacitor is equivalent to an open circuit after being fully charged, at this time, since the output end of the power supply diagnosis circuit 101 outputs a low-level signal, the first switch tube is turned off, and the second switch tube is also turned off, then the power supply path between the power supply module 20 and the load 30 is disconnected, and the load 30 enters a safe state, thereby prolonging the safe shutdown response time, avoiding the false cut-off of the power supply module 20 caused by the interference signal, and the response time can be adjusted according to the requirements, and the implementation is flexible.

[0090] The above embodiment exemplarily introduces the circuit structure of the switching circuit 102 and the bypass circuit 103. Hereinafter, the implementation of the power supply diagnosis circuit 101 is exemplarily introduced.

[0091] Optionally, as described above, the power supply diagnosis circuit 101 can be an integrated chip with overvoltage and undervoltage monitoring function, i.e., the power supply diagnosis circuit 101 includes a second input end connected with a power input end of the load 30, and the power supply diagnosis circuit 101 is configured to monitor the overvoltage and undervoltage of the load 30.

[0092] Optionally, in the case that the load 30 has multiple power supply paths, the power supply diagnosis circuit 101 can also be an integrated chip with overvoltage and undervoltage monitoring function, i.e., the power supply diagnosis circuit 101 includes multiple second input ends, each of which is connected with a power input end of the load 30.

[0093] Optionally, the power supply diagnosis circuit 101 can include an overvoltage diagnosis circuit and / or an undervoltage diagnosis circuit, wherein a first input end of the overvoltage diagnosis circuit is connected with the power supply module 20, a second input end of the overvoltage diagnosis circuit is connected with the load 30, and an output end of the overvoltage diagnosis circuit is connected with the switching circuit 102; a first input end of the undervoltage diagnosis circuit is connected with the power supply module 20, a second input end of the undervoltage diagnosis circuit is connected with the load 30, and an output end of the undervoltage diagnosis circuit is connected with the switching circuit 102, and the output type of the overvoltage diagnosis circuit and the undervoltage diagnosis circuit is open-drain output. In the case that the power supply diagnosis circuit 101 includes the overvoltage diagnosis circuit and the undervoltage diagnosis circuit, the output signal lines of the overvoltage diagnosis circuit and the undervoltage diagnosis circuit are connected with each other and then connected with the switching circuit 102, for example, as shown in the embodiment of FIG. 6, the output signal lines of the overvoltage diagnosis circuit and the undervoltage diagnosis circuit are connected with each other and then connected with the first end of the first switch tube. Figure 4 or Figure 3 For example, as shown in the embodiment of FIG. 6, the output signal lines of the overvoltage diagnosis circuit and the undervoltage diagnosis circuit are connected with each other and then connected with the first end of the first switch tube.

[0094] Thus, in actual implementation, corresponding power supply diagnosis circuits 101 can be selected according to different scenarios, which improves the implementation flexibility of the embodiments of the present application.

[0095] Optionally, the power supply diagnosis circuit 101 includes a comparator and a reference power supply module 20 connected with the comparator, a first input end of the comparator is connected with the power supply module 20, a second input end of the comparator is connected with the load 30, the output type of the comparator is open-drain output, and an output end of the comparator is connected with the switching circuit 102. After the comparator detects the input voltage of the load 30, the input voltage is compared with the reference voltage provided by the reference power supply module 20. By comparing the input voltage with the reference voltage, it can be identified whether the input voltage is too large or too small. Then, the comparator controls the switching circuit 102 to be disconnected (for example, the comparator outputs a low voltage signal), so as to cut off the power supply path between the power supply module 20 and the load 30, thereby ensuring the system safety. Moreover, the power supply diagnosis circuit 101 is built by the comparator and the reference power supply module 20, which has a simple circuit structure and is easy to implement, and is conducive to reducing the hardware cost.

[0096] The comparators can be one or more. When there are multiple comparators, the first input terminal of each comparator is connected to the power supply module 20, and its second input terminal is connected to the load 30. Each comparator has an open-drain output. The output signal lines of multiple comparators are connected together and then connected to the switching circuit 102. For example, using... Figure 4 or Figure 4 In the example shown, the output signal lines of multiple comparators are connected and then connected to the first terminal of the first switching transistor.

[0097] In this embodiment, a low-cost, highly reliable safety control circuit 10 is built using simple discrete components such as resistors and transistors. In addition, the safety control circuit 10 uses very few components, which is conducive to realizing product miniaturization design.

[0098] The above embodiment is described with one safety control circuit 10 connected between the power module 20 and the load 30.

[0099] Optionally, there may be multiple safety control circuits 10 connected in series between the power module 20 and the load 30.

[0100] For example, in Figure 5 Based on the illustrated embodiments, see also Figure 6 There are two safety control circuits 10, and the two-level safety control circuits 10 are connected in series between the power module 20 and the load 30. The circuit structure and circuit function of each safety control circuit 10 are the same. The two-level safety control circuits 10 constitute a 1002 power diagnostic architecture. When any safety control circuit 10 fails (for example, one or more components of the safety control circuit 10 fail), the other safety control circuits 10 can use the implementation method of any of the above embodiments to ensure that the system is powered on smoothly, and realize the power diagnostic and automatic safe shutdown of the system after the system is powered on, further improving the system safety.

[0101] In this embodiment of the application, by designing a 1oo2 power diagnostic architecture, the impact of the cumulative failure of the safety control circuit 10 on the system safety function is considered, that is, the impact of the failure of the safety control circuit 10 itself on the load 30 or the system safety function. The 1oo2 power diagnostic architecture has high reliability and fault accumulation defense function. When one of the first-level safety control circuits 10 fails, and a power failure occurs again, the fault can still be diagnosed by other safety control circuits 10, so that the load 30 can quickly enter a safe state and ensure the safe and reliable operation of the load 30.

[0102] The following, combined withFigure 4 ,right Figure 6 The working principle of the safety control circuit 10 in the illustrated embodiment is described by way of example. Since each safety control circuit 10 has the same circuit function, any one level of safety control circuit 10 will be used as an example for description.

[0103] ​ In the diagram, T1 is the power-on time of the power diagnostic circuit 101, T2 is the power-on time of load 1 and load 2, T3 is the power-on tolerance time of the power diagnostic circuit 101, T0 is the moment when load 1 experiences overvoltage interference, T5 is the moment when load 1 experiences overvoltage fault, and T6 is the shutdown response time.

[0104] During the power-on process of load 1 and load 2, the power module 20 charges the first capacitor in the bypass circuit 103. After time T1, the power diagnostic circuit 101 outputs a low-level reset signal. The first and second switching transistors in the switching circuit 102 are disconnected. Due to the characteristic that the capacitor voltage cannot change abruptly, the first capacitor is equivalent to a short circuit. At this time, the third switching transistor in the bypass circuit 103 is turned on, and the third switching transistor bypasses the first switching transistor. In this way, the second switching transistor is turned on, and load 1 and load 2 are successfully powered on at time T2.

[0105] After load 1 and load 2 are successfully powered on, the power diagnostic circuit 101 detects that the input voltage of load 1 and load 2 is normal. The output terminal of the power diagnostic circuit 101 outputs a high-level reset signal, so that the first switch is turned on, and the second switch can remain on. Load 30 works normally. After the first capacitor is fully charged, the bypass circuit 103 is disconnected, the third switch is turned off, and the power diagnostic circuit 101 continues to perform power diagnostics on the system.

[0106] At time T0, overvoltage interference occurs in load 1, causing its input voltage to momentarily exceed the normal operating voltage of load 30. At this time, the power diagnostic circuit 101 triggers overvoltage protection, outputting a low-level signal. The first switch is turned off, and the second capacitor is charging. The second capacitor, the first resistor, and the second resistor can form a circuit, creating a voltage difference across the second resistor. At this time, the second switch can conduct normally, and load 30 operates normally. When the interference disappears, the input voltage of load 30 returns to normal, the power diagnostic circuit 101 outputs a high-level signal, the first switch is turned on, and the second switch is also turned on normally. The second capacitor completes its discharge, and load 30 operates normally, thus avoiding the accidental disconnection of power module 20 caused by interference signals.

[0107] At the T5 moment, the load 1 has an overvoltage fault, the input voltage of the load 1 exceeds the voltage when the load 30 normally works, at this time, the power supply diagnosis circuit 101 triggers the overvoltage protection, the first switch tube is disconnected, the second capacitor is in the charging state, the second capacitor and the first resistor and the second resistor can form a loop, there is a voltage difference between the two ends of the second resistor, at this time, the second switch tube can normally conduct, if the interference does not disappear after the T6 (off response time) time ends, it is indicated that the overvoltage fault occurs, after the second capacitor is fully charged, the second capacitor is equivalent to a break, at this time, since the output end of the power supply diagnosis circuit 101 outputs a low-level signal, the first switch tube is disconnected, and the second switch tube is also disconnected, then the power supply path between the power supply module 20 and the load 30 is disconnected, and the load 30 enters a safe state, thereby prolonging the safe off response time, avoiding the false shutdown of the power supply module 20 caused by the interference signal, and the response time can be adjusted according to requirements, and the implementation is flexible.

[0108] In the embodiment of the application, the complete safety control circuit 10 is built by using the power supply diagnosis circuit 101 and the separated components, the power supply diagnosis and the safe automatic shutdown can be realized, the system can be ensured to be powered on smoothly, the circuit cost is low, a perfect power supply diagnosis scheme is provided for the products with the safety level of SIL3 or SIL4, the diagnosis coverage is greater than or equal to 99%, and the scheme can also be applied to the mechanical function safety industry and meet the requirements of the related safety standards of the mechanical function safety industry.

[0109] In one embodiment, a device, for example, an industrial device, is also provided, the device includes the power supply module 20, the load 30, and the safety control circuit 10 as described in any of the above embodiments, and the safety control circuit 10 is connected between the power supply module 20 and the load 30.

[0110] The related implementation and beneficial effects of the device in the embodiment of the application can be referred to the related description in the above safety control circuit 10, which will not be described here.

[0111] In the description of the specification, the description referring to the terms “some embodiments”, “other embodiments”, and the like means that the specific features, structures, materials, or characteristics described in combination with the embodiments or examples are contained in at least one embodiment or example of the application. In the specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example.

[0112] The technical features of the above-described embodiments can be combined arbitrarily, and for the sake of concise description, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, it should be considered that the combinations are within the scope of the specification.

[0113] The above-described embodiments are merely illustrative of several embodiments of the present application, which are described in more detail and in a specific manner, but should not be construed as limiting the scope of the present application. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A safety control circuit, characterized by, The safety control circuit is used for connecting between a power module and a load, and comprises: a power diagnosis circuit, a first input end of the power diagnosis circuit being connected with the power module, and a second input end of the power diagnosis circuit being connected with the load; a switch circuit, the switch circuit being connected with the power module and the load respectively, and the switch circuit being further connected with an output end of the power diagnosis circuit; a bypass circuit, the bypass circuit being connected with the power module and the switch circuit respectively; wherein, the bypass circuit is used for controlling the switch circuit to turn on a power supply path between the power module and the load during a power-on process of the load, and the bypass circuit is further used for being in an off state after the power-on of the load.

2. The safety control circuit of claim 1, wherein, The switch circuit comprises: a first switch tube, a first end of the first switch tube being connected with the output end of the power diagnosis circuit, and a second end of the first switch tube being grounded; a first resistor, a first end of the first resistor being connected with a third end of the first switch tube, and the bypass circuit being connected between the first end of the first resistor and the third end of the first switch tube; a second switch tube, a first end of the second switch tube being connected with a second end of the first resistor, a second end of the second switch tube being connected with the power module, and a third end of the second switch tube being connected with the load; a second resistor, a first end of the second resistor being connected with the first end of the second switch tube, and a second end of the second resistor being connected with the second end of the second switch tube.

3. The safety control circuit of claim 2, wherein, The bypass circuit comprises: a first capacitor, a first end of the first capacitor being connected with the power module; a third resistor, a first end of the third resistor being connected with a second end of the first capacitor; a third switch tube, a first end of the third switch tube being connected with a second end of the third resistor, a second end of the third switch tube being grounded, and a third end of the third switch tube being connected between the first end of the first resistor and the third end of the first switch tube.

4. The safety control circuit of claim 3, wherein, The safety control circuit further comprises: a second capacitor, a first end of the second capacitor being connected between the first end of the first resistor and the third end of the first switch tube, and a second end of the second capacitor being grounded.

5. The safety control circuit of claim 3, wherein, The bypass circuit further comprises: a voltage stabilizing module, a first end of the voltage stabilizing module being connected with the first input end of the power diagnosis circuit, and a second end of the voltage stabilizing module being grounded.

6. The safety control circuit of claim 1, wherein, The power diagnosis circuit comprises a plurality of second input ends, each of the second input ends being connected with each power input end of the load respectively.

7. The safety control circuit of claim 1, wherein, The power diagnosis circuit comprises an overvoltage diagnosis circuit and / or an undervoltage diagnosis circuit; wherein, a first input end of the overvoltage diagnosis circuit being connected with the power module, a second input end of the overvoltage diagnosis circuit being connected with the load, and an output end of the overvoltage diagnosis circuit being connected with the switch circuit; a first input end of the undervoltage diagnosis circuit being connected with the power module, a second input end of the undervoltage diagnosis circuit being connected with the load, and an output end of the undervoltage diagnosis circuit being connected with the switch circuit.

8. The safety control circuit of claim 1, wherein, The power supply diagnosis circuit comprises a comparator and a reference power module connected with the comparator; wherein, a first input end of the comparator is connected with the power module, a second input end of the comparator is connected with the load, and an output end of the comparator is connected with the switch circuit.

9. The safety control circuit according to any of claims 1-8, characterized in that, The number of the safety control circuits is multiple, and multiple safety control circuits are connected in series between the power module and the load.

10. An apparatus, comprising: The device comprises a power module, a load, and a safety control circuit according to any one of claims 1-9, and the safety control circuit is connected between the power module and the load.

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