Isolation type safety barrier circuit for modulation type bus and safety barrier with isolation type safety barrier circuit

Abstract

The isolation type guard grating circuit comprises an EMC (Electro Magnetic Compatibility) protection, rectification and current limiting circuit, the input end of the EMC protection, rectification and current limiting circuit is connected with a direct current bus end, and the output end of the EMC protection, rectification and current limiting circuit is connected with the input end of a first fuse; the input end of the isolation transformer T1 is connected with the output end of the EMC protection, rectification and current limiting circuit and the output end of the first fuse, and the output end of the isolation transformer T1 is connected with the input end of the second fuse and the input end of the voltage limiting circuit. The input end of the bus level conversion circuit is connected with the output end of the voltage limiting circuit, and the output end is connected with the first input end of the code return current detection and comparison circuit; the input end of the signal isolation circuit is connected with the first output end of the code return current detection and comparison circuit, and the output end is connected with the first input end of the bus function circuit. According to the isolation type safety barrier circuit of the modulation type bus, the bus of the isolation type safety barrier does not need to be grounded, and communication faults caused by loop grounding can be fundamentally solved.

Description

Technical Field

[0001] The utility model relates to a detector in the field of fire safety, specifically to an isolation type safety barrier circuit for a modulated bus of the detector and a safety barrier having the same. Background Art

[0002] The intrinsically safe detector specified in GB / T3836.4 needs to be connected with a safety barrier during use. Although the simple Zener type safety barrier has a simple structure and low cost, in order to meet the intrinsically safe requirements, the Zener type safety barrier must be grounded. In the application scenarios of the modulated bus (the bus transmits signals while providing power), in many cases, grounding the bus will cause communication failures of the detectors connected to the bus. To solve the communication failures of the intrinsically safe detectors, the isolation type safety barrier is proposed. The bus of the isolation type safety barrier does not need to be grounded, which can fundamentally solve the communication failures caused by grounding the loop. There are many types of modulated buses, and the implementation methods of the corresponding isolation type safety barriers are also different.

[0003] The safety barrier is required to be adapted to the 11SF protocol, and the protocol includes: a modulated bus protocol, which defines: ① Controller loop: 19V - 27V is the high level, 9.5 - 11V is the intermediate level, and 0V - 2V is the zero level. ② Current signal range, for the controller, the normal value range is 2mA ≤ S < 12mA, and the alarm value range is 12mA ≤ S < 30mA. Content of the Utility Model

[0004] The technical problem to be solved by the utility model is an isolation type safety barrier circuit for a modulated bus and a safety barrier having the same. The bus of the isolation type safety barrier does not need to be grounded, which can fundamentally solve the communication failures caused by grounding the loop.

[0005] To solve the above technical problem, the utility model provides an isolation type safety barrier circuit for a modulated bus, which includes:

[0006] EMC protection, rectification and current limiting circuit: its input end is connected with the DC bus end, and its output end is connected with the input end of the first fuse;

[0007] Isolation transformer T1: its input end is connected with the output end of the EMC protection, rectification and current limiting circuit and the output end of the first fuse, and its output end is connected with the second fuse and the input end of the voltage limiting circuit;

[0008] Bus level conversion circuit: its input end is connected with the output end of the voltage limiting circuit, and its output end is connected with the first input end of the return code current detection and comparison circuit 400;

[0009] Signal isolation circuit 200: Its input terminal is connected to the first output terminal of the return code current detection and comparison circuit 400, and its output terminal is connected to the first input terminal of the bus function circuit 300;

[0010] Bus function circuit 300: Its second input terminal is connected to the output terminal of the fuse-limiting voltage protection circuit, and its output terminal is connected to the input terminal of the signal isolation circuit 200;

[0011] Fuse-limiting voltage protection circuit: Its input terminal is connected in series with the output terminal of the EMC protection / rectification circuit 100 and the bus power input terminal.

[0012] Furthermore: The second output terminal of the bus level conversion circuit is also connected to the input terminal of the intrinsically safe side current limiting protection circuit, and the output terminal of the intrinsically safe side current limiting protection circuit is the bus power output terminal.

[0013] Furthermore, the node between the output terminals of the bus level conversion circuit and the voltage limiting circuit is also respectively connected to the second input terminal of the return code current detection and comparison circuit 400 and the input terminal of the first low-dropout regulator (LDO). The output terminal of the first low-dropout regulator (LDO) is also connected to the input terminal of the first secondary voltage limiting protection circuit. The first output terminal of the first secondary voltage limiting protection circuit is connected to supply power to the third input terminal of the return code current detection and comparison circuit 400, and the second output terminal of the first secondary voltage limiting protection circuit is connected to supply power to the signal isolation circuit 200.

[0014] Furthermore, the node where the second input terminal of the bus function circuit 300 is connected to the output terminal of the fuse-limiting voltage protection circuit is also connected to the input terminal of the second low-dropout regulator (LDO). The output terminal of the second low-dropout regulator (LDO) is connected to supply power to the bus function circuit 300 and the signal isolation circuit 200.

[0015] Furthermore, a second secondary voltage limiting protection circuit can also be connected in series between the output terminal of the second low-dropout regulator (LDO) and the bus function circuit 300.

[0016] Furthermore, the signal isolation circuit 200 includes a first isolation element and a second isolation element connected in parallel.

[0017] Further, the intrinsically safe side current limiting protection circuit includes: the other end of resistor R299 is connected to the other end of resistor R69, one end of resistor R282, the negative electrode of transient suppression diode D30, and the third pin of field effect transistor U8. The first pin of triode Q9 is connected to the other end of resistor R282. The second pin of triode Q9 is connected to the positive electrode of transient suppression diode D30, the first pin of field effect transistor U8, and one end of resistor R74. The other end of resistor R74 is grounded. The second pin of field effect transistor U8 is connected to the fourth pin of field effect transistor U8, one end of resistor R300, one end of resistor R80, and the third pin of triode Q15. The other end of resistor R80 is connected to the other end of resistor R300, one end of resistor R283, the negative electrode of transient suppression diode D34, and the third pin of field effect transistor U9. The first pin of triode Q15 is connected to the other end of resistor R283. The second pin of triode Q15 is connected to the positive electrode of transient suppression diode D34, the first pin of field effect transistor U9, and one end of resistor R82. The other end of resistor R82 is grounded. The second pin of field effect transistor U9 is connected to the second pin of field effect transistor U9 and the output end.

[0018] The technical effect of the present utility model is as follows: The isolated safety barrier and its circuit for a modulation type bus of the present utility model do not require the bus of the isolated safety barrier to be grounded, which can fundamentally solve the communication failure caused by the loop being grounded.

[0019] ① Controller loop: 19V to 27V is high level, 9.5 to 11V is intermediate level, and 0V to 2V is zero level.

[0020] ② Current signal range: For the controller, the normal value range is 2mA ≤ S < 12mA, the alarm value range is 12mA ≤ S < 30mA), and the fault value range is 0mA ≤ S < 2mA and S ≥ 30mA; for field components (detectors), the current signal range of normal value is 5.0mA to 8.0mA, and the alarm value range is 17.0mA to 24.0mA.

[0021] ③ The magnitude of the width of the high, intermediate, and zero levels of the signal is at the ms level, such as 4ms, 8ms, 12ms, etc. The falling edge and rising edge time from high level to intermediate level, from high level to zero level, etc. generally do not exceed 300us) of the isolated safety barrier. Description of the Drawings

[0022] Figure 1 is the structural reference diagram of the isolated safety barrier circuit for the modulation type bus of the present utility model;

[0023] Figure 2-1 and Figure 2-2 is the circuit reference diagram corresponding to the upper left part of the left side of the dotted dividing line corresponding to Figure 1 i.e., the circuit from DC24V input to the isolator;

[0024] Figure 3The left side of the dashed dividing line corresponds to Figure 1 The left side of the lower part of the left dashed dividing line, i.e., the circuit reference diagram of the bus input to the signal isolation component;

[0025] Figure 4 The left side of the dashed dividing line corresponds to Figure 1 The circuit diagram between the two dashed dividing lines, i.e., from the isolation transformer to the bus level conversion circuit. The right side of the dashed dividing line corresponds to Figure 1 The right dashed dividing line is the circuit reference diagram of the side line protection output circuit in this case;

[0026] Figure 5 It is the temperature compensation diagram of the output current limiting of the isolated safety barrier. Specific implementation mode

[0027] The following further illustrates the present utility model in conjunction with the attached drawings and specific embodiments, so that those skilled in the art can better understand the present utility model and be able to implement it, but the cited embodiments do not limit the present utility model.

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model in conjunction with the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the protection scope of the present utility model.

[0029] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "top / bottom end", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present utility model, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "provided with", "sheathed / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0031] Such as Figures 1 to 5As shown, the present utility model discloses an isolated safety barrier circuit for a modulation type bus. The reference numerals, models, and text descriptions in the figure are for reference only. Deleting and changing the reference numerals, models, and text descriptions do not affect the protection scope of the circuit. The safety barrier circuit specifically includes the following:

[0032] EMC protection, rectification, and current limiting circuit: Its input terminal is connected to the DC bus terminal, and its output terminal is connected to the input terminal of the first fuse;

[0033] Isolation transformer T1: Its input terminal is connected to the output terminal of the EMC protection, rectification, and current limiting circuit and the output terminal of the first fuse, and its output terminal is connected to the input terminal of the second fuse and the voltage limiting circuit;

[0034] Bus level conversion circuit: Its input terminal is connected to the output terminal of the voltage limiting circuit, and its output terminal is connected to the first input terminal of the return code current detection and comparison circuit 400;

[0035] Signal isolation circuit 200: Its input terminal is connected to the first output terminal of the return code current detection and comparison circuit 400, and its output terminal is connected to the first input terminal of the bus function circuit 300;

[0036] Bus function circuit 300: Its second input terminal is connected to the output terminal of the fuse voltage limiting protection circuit, and its output terminal is connected to the input terminal of the signal isolation circuit 200;

[0037] Fuse voltage limiting protection circuit: Its input terminal is connected in series with the output terminal of the EMC protection / rectification circuit and the bus power input terminal.

[0038] Furthermore, the second output terminal of the bus level conversion circuit is also connected to the input terminal of the intrinsically safe side current limiting protection circuit, and the output terminal of the intrinsically safe side current limiting protection circuit is the bus power output terminal.

[0039] Furthermore, the node between the output terminals of the bus level conversion circuit and the voltage limiting circuit is also respectively connected to the second input terminal of the return code current detection and comparison circuit 400 and the input terminal of the first linear voltage regulator LDO. The output terminal of the first linear voltage regulator LDO is also connected to the input terminal of the first secondary voltage limiting protection circuit. The first output terminal of the first secondary voltage limiting protection circuit is connected to supply power to the third input terminal of the return code current detection and comparison circuit 400, and the second output terminal of the first secondary voltage limiting protection circuit is connected to supply power to the signal isolation circuit 200.

[0040] Furthermore, the node where the second input terminal of the bus function circuit 300 is connected to the output terminal of the fuse voltage limiting protection circuit is also connected to the input terminal of the second linear voltage regulator LDO. The output terminal of the second linear voltage regulator LDO is connected to supply power to the bus function circuit 300 and the signal isolation circuit 200.

[0041] Furthermore, a second secondary voltage limiting protection circuit may be connected in series between the output terminal of the second low-dropout regulator (LDO) and the bus function circuit 300.

[0042] Furthermore, the signal isolation circuit 200 includes a first isolation element and a second isolation element connected in parallel.

[0043] Figure 2-1 and Figure 2-2 The output voltage of the isolated safety barrier is 21~23V, the power supply input of the isolated safety barrier is DC24V input, the power supply input of the isolated safety barrier, and the Um voltage of the loop input is 250Vac. The circuit, parameters, power supply, loop input, and loop output interface that meet the intrinsic safety requirements under this nominal voltage are provided. The MC protection, rectification, and current limiting circuit, the EMC protection, rectification, and current limiting circuit 111, and the EMC protection, rectification, and current limiting circuit 110 shown in the circuit structure block diagram include: a fuse F1 connected to the pin of the transformer T1 and a zener diode D2 connected in parallel to the input terminal, a fuse F2, and diodes D9 and D10 connected in parallel.

[0044] Figure 2-1 、 Figure 2-2 and Figure 3 The block diagram shows that the bus function circuit 300 is connected, the Um voltage of the loop input is 250Vac, the comparison threshold for the loop waveform detection of the safety barrier is defined as high level when the controller loop voltage is about ≥13.4V, zero level when the loop voltage ≤2.65V, and medium level between 2.65V and 13.4V. The loop waveform that meets the requirements of the detector is modulated by a high-speed optocoupler and the subsequent waveform modulation current, including the comparison threshold, isolation transmission, and waveform modulation scheme, etc.

[0045] Figure 3 The return code current detection and comparison circuit 400 is shown, which is a circuit for isolating and generating a normal signal current and an alarm signal current. Using two optocouplers, output peripheral resistors, a comparator, transistors, and other components, it realizes the output of a current signal of about 6mA and an alarm signal of 18mA.

[0046] Figure 5 The temperature compensation diagram for the output current limiting of the isolated safety barrier is shown. The resistors R299 and R300 use 1kΩ (Fenghua 1KΩ NTC resistor (CMFB102J3200HA) or Murata 220R NTC, and other NTC resistors that meet the temperature compensation requirements) for temperature compensation, which can further expand the load-carrying capacity of the isolated safety barrier at high temperatures.

[0047] Such as Figure 4The intrinsically safe side current limiting protection circuit is shown as follows, including: The other end of resistor R299 is connected to the other end of resistor R69, one end of resistor R282, the negative electrode of transient suppression diode D30, and the third pin of field effect transistor U8. The first pin of triode Q9 is connected to the other end of resistor R282. The second pin of triode Q9 is connected to the positive electrode of transient suppression diode D30, the first pin of field effect transistor U8, and one end of resistor R74. The other end of resistor R74 is grounded. The second pin of field effect transistor U8 is connected to the fourth pin of field effect transistor U8, one end of resistor R300, one end of resistor R80, and the third pin of triode Q15. The other end of resistor R80 is connected to the other end of resistor R300, one end of resistor R283, the negative electrode of transient suppression diode D34, and the third pin of field effect transistor U9. The first pin of triode Q15 is connected to the other end of resistor R283. The second pin of triode Q15 is connected to the positive electrode of transient suppression diode D34, the first pin of field effect transistor U9, and one end of resistor R82. The other end of resistor R82 is grounded. The second pin of field effect transistor U9 is connected to the second pin of field effect transistor U9 and the output terminal.

[0048] The above embodiments are only preferred embodiments given to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. An isolated safety barrier circuit for a modulated bus, characterized in that, It includes: EMC protection, rectification and current-limiting circuit: Its input terminal is connected to the DC bus terminal, and its output terminal is connected to the input terminal of the first fuse; Isolation transformer T1: Its input terminal is connected to the output terminal of the EMC protection, rectification and current-limiting circuit and the output terminal of the first fuse, and its output terminal is connected to the input terminal of the second fuse and the voltage-limiting circuit; Bus level conversion circuit: Its input terminal is connected to the output terminal of the voltage-limiting circuit, and its output terminal is connected to the first input terminal of the return code current detection and comparison circuit; Signal isolation circuit: Its input terminal is connected to the first output terminal of the return code current detection and comparison circuit, and its output terminal is connected to the first input terminal of the bus function circuit; Bus function circuit: Its second input terminal is connected to the output terminal of the fuse voltage-limiting protection circuit, and its output terminal is connected to the input terminal of the signal isolation circuit; Fuse voltage-limiting protection circuit: Its input terminal is connected in series with the output terminal of the EMC protection / rectification circuit and the bus power input terminal.

2. The isolated safety barrier circuit for a modulated bus according to claim 1, characterized in that: The second output terminal of the bus level conversion circuit is also connected to the input terminal of the intrinsically safe side current-limiting protection circuit, and the output terminal of the intrinsically safe side current-limiting protection circuit is the bus power output terminal.

3. The isolated safety barrier circuit for a modulation type bus according to claim 1, characterized in that, The node between the output terminals of the bus level conversion circuit and the voltage-limiting circuit is also respectively connected to the second input terminal of the return code current detection and comparison circuit and the input terminal of the first linear voltage regulator LDO. The output terminal of the first linear voltage regulator LDO is also connected to the input terminal of the first secondary voltage-limiting protection circuit. The first output terminal of the first secondary voltage-limiting protection circuit is connected to the third input terminal of the return code current detection and comparison circuit for power supply, and the second output terminal of the first secondary voltage-limiting protection circuit is connected to the signal isolation circuit for power supply.

4. An isolated safety barrier circuit for a modulation type bus according to claim 1, characterized in that, The node where the second input terminal of the bus function circuit is connected to the output terminal of the fuse voltage-limiting protection circuit is also connected to the input terminal of the second linear voltage regulator LDO. The output terminal of the second linear voltage regulator LDO is connected to supply power to the bus function circuit and the signal isolation circuit.

5. An isolated safety barrier circuit for a modulated bus according to claim 4, characterized in that, A second secondary voltage-limiting protection circuit can also be connected in series between the output terminal of the second linear voltage regulator LDO and the bus function circuit.

6. An isolated safety barrier circuit for a modulation type bus according to claim 1, characterized in that, The signal isolation circuit includes a first isolation element and a second isolation element connected in parallel.

7. The isolated safety barrier circuit for a modulated bus according to claim 2, characterized in that, The intrinsically safe side current-limiting protection circuit includes: the other end of resistor R299 is connected to the other end of resistor R69, one end of resistor R282, the negative electrode of transient suppression diode D30, and the third pin of field effect transistor U8; the first pin of triode Q9 is connected to the other end of resistor R282; the second pin of triode Q9 is connected to the positive electrode of transient suppression diode D30, the first pin of field effect transistor U8, and one end of resistor R74; the other end of resistor R74 is grounded; the second pin of field effect transistor U8 is connected to the fourth pin of field effect transistor U8, one end of resistor R300, one end of resistor R80, and the third pin of triode Q15; the other end of resistor R80 is connected to the other end of resistor R300, one end of resistor R283, the negative electrode of transient suppression diode D34, and the third pin of field effect transistor U9; the first pin of triode Q15 is connected to the other end of resistor R283; the second pin of triode Q15 is connected to the positive electrode of transient suppression diode D34, the first pin of field effect transistor U9, and one end of resistor R82; the other end of resistor R82 is grounded; the second pin of field effect transistor U9 is connected to the second pin of field effect transistor U9 and the output terminal.

8. An isolated safety barrier for a modulated bus, characterized in that, It includes the isolated safety barrier circuit for the modulation type bus according to any one of claims 1 to 7.

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