A smart bus isolator and a method for fault isolation in a bus system

Abstract

This invention relates to an intelligent bus isolator and a bus system fault isolation method, belonging to the field of electrical isolation and bus communication technology. The isolator uses a rectifier bridge and back-to-back field-effect transistors to form a bidirectional switching module, achieving polarity-free installation. The bus system includes a power supply control host with dual-mode ports and a bus network with polarity-free isolators connected in series. Under normal conditions, the first port supplies power, and the second port detects. In case of a fault, the host connects the two ports in parallel to supply power, reconstructing the power supply path. Due to the polarity-free characteristic of the isolator, current can conduct in reverse, thereby quickly restoring power to the non-faulty section of the original faulty branch. Subsequently, the host obtains the status of each isolator through centralized communication, and accurately locates and isolates the fault based on the network topology. This invention has the advantages of simple installation, rapid recovery after a fault, and accurate location, solving the problems of polarity sensitivity and coarse isolation of traditional isolators, and significantly improving the reliability and ease of installation and maintenance of the bus system.

Description

Technical Field

[0001] This invention relates to the field of electrical isolation and bus communication technology, and in particular to an intelligent bus isolator and a bus system fault isolation method for a fire protection two-bus system. Background Technology

[0002] In fire alarm systems, two-bus technology is widely used due to its simple wiring and low cost. To prevent system failure caused by short circuits or other faults in the bus lines, bus isolators are typically installed at intervals along the bus. However, existing bus isolator solutions have the following main shortcomings:

[0003] 1. Strict polarity requirements during installation: The most common isolation devices (such as diodes or unidirectional electronic switches) have clearly defined input and output directions. The polarity must be correctly identified during installation; otherwise, not only will the isolation function fail, but reverse connection may also damage the equipment or cause system malfunctions, leading to inconvenience and risks during construction and maintenance.

[0004] 2. Wide range of impact from faults: When a fault occurs, the isolator operates based on local analog detection (such as voltage comparison), which will cause all downstream devices of the isolator to lose power, resulting in significant functional loss.

[0005] 3. Ambiguous fault location: Each isolator operates independently, making it impossible for the system host to know which isolator activated and for what reason, let alone the precise location of the fault. Furthermore, due to detection errors or signal drift, multiple isolators may activate simultaneously or fail to activate, resulting in inaccurate fault isolation and potentially exaggerating the affected area. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an intelligent bus isolator and a bus system fault isolation method, which overcomes the defects of the prior art such as the need to distinguish the polarity of the bus isolator, the limitation of the installation direction, the inaccuracy of fault isolation, and the low system reliability, so as to achieve polarity-free and directionless installation, accurate fault point location and local isolation, and improve the stability and safety of the fire protection two-bus system.

[0007] The technical solution adopted by the present invention to solve its technical problem is: an intelligent bus isolator, comprising a bidirectional switching module and a control and communication module;

[0008] The bidirectional switch module includes a rectifier bridge and at least one pair of back-to-back field-effect transistors connected to the output terminal of the rectifier bridge. The AC side of the rectifier bridge is connected to the bus terminal of the isolator, so that the isolator does not need to distinguish the direction of current input when connected to the bus.

[0009] This structure ensures that regardless of which side of the isolator the current flows in from, it can be rectified by the rectifier bridge to control the conduction of the field-effect transistor, thus achieving non-polarity installation, meaning that there is no need to distinguish between the input and output directions during installation.

[0010] The control and communication module is connected to the control terminal of the bidirectional switch module. The control and communication module controls the on / off state of the bidirectional switch module and realizes bidirectional data communication with an external controller.

[0011] Furthermore, the control and communication module of the present invention includes a microcontroller, a signal receiving circuit, and a signal transmitting circuit; the signal receiving circuit is used to couple and demodulate communication signals from the upper-level host from the bus; the signal transmitting circuit is used to send the status information of the isolator to the bus under the control of the microcontroller.

[0012] Furthermore, the present invention also includes a local protection unit for monitoring the electrical parameters of the path in which the bidirectional switch module is located, and triggering the bidirectional switch module to shut down when the electrical parameters exceed a preset threshold. When an overcurrent or short circuit condition is detected, the bidirectional switch module can be triggered to shut down, achieving rapid hardware protection.

[0013] Meanwhile, the present invention also provides a fire protection two-wire system, including,

[0014] The power supply control host has a first port, a second port, and a port parallel switch connecting the first port and the second port. During normal operation, the power supply control host controls the first port to operate in power supply and communication mode, and controls the second port to operate in high-impedance detection mode.

[0015] A bus network, wherein the first port and the second port are respectively connected to the bus network;

[0016] Multiple intelligent bus isolators, as described above, are connected in series in the bus network; field devices are connected in parallel to the various sections divided by the multiple isolators.

[0017] When a fault occurs, the power supply control host responds to the fault triggering condition by controlling the parallel switch of the port to close and switching the second port to power supply and communication mode, so that the first port and the second port are connected in parallel as the power supply access point of the bus network; it obtains the status information of the intelligent bus isolator by communicating with it, and determines the fault location according to the pre-stored network topology information.

[0018] Furthermore, the fault triggering condition of the present invention is that the second port detects a short circuit, an open circuit, or a communication interruption in the bus network.

[0019] Furthermore, during system initialization, the power supply control host of the present invention records the connection sequence of each intelligent bus isolator through communication to form the network topology information.

[0020] Furthermore, since the bus isolator near the fault point has automatically disconnected due to hardware protection, the original power supply path is blocked. After the first and second ports are connected in parallel, the power supply current will naturally enter the network from these two parallel points and automatically select a passable path according to the network topology. Crucially, due to the bidirectional conduction characteristic of the non-polarized bus isolator, the current can flow in reverse without hindrance. Therefore, the non-faulty section on the original faulty branch located upstream of the disconnection point can obtain power from the opposite direction of the initial power supply, thereby quickly restoring power supply and communication.

[0021] This invention also provides a fault isolation method for the aforementioned fire protection two-wire system, comprising the following steps:

[0022] S1. Normal power supply: Power is supplied to the bus network and communication is conducted through the first port, while the second port is in detection mode;

[0023] S2. Fault Response and Reconfiguration: When the second port detects a fault in its connection line, the power supply control host closes the parallel switch and switches the second port to power supply and communication mode;

[0024] S3, Path Reconstruction and Restoration: Power is supplied to the bus network through the first and second ports connected in parallel. The bidirectional conduction characteristics of the intelligent bus isolator are used to restore power supply and communication to the non-faulty sections of the network along the reconstructed path.

[0025] S4. Location and Isolation: After network communication is restored, the power supply control host communicates with all online non-polarized bus isolators via broadcast query commands to obtain their unique addresses and current switching status (on / off). Based on the network topology information learned and stored during system initialization (i.e., the connection order of each isolator), the power supply control host performs logical analysis in conjunction with the obtained status information to accurately calculate the location of the fault point. Subsequently, a control command is issued to keep or disconnect the isolators near the fault point, achieving precise isolation within the smallest possible range.

[0026] Furthermore, prior to step S2, the intelligent isolator closest to the fault point detects an overcurrent or short circuit and triggers the bidirectional switch module to shut down, thus achieving rapid hardware protection.

[0027] Furthermore, after step S4, the present invention also includes the step of...

[0028] S5. When the system detects that the fault has been cleared and the line parameters have returned to normal, the intelligent bus isolator that has been disconnected will automatically restore the conduction state of its switching unit.

[0029] The beneficial effects of this invention are:

[0030] 1. The bus isolator adopts a non-polarity structure, which means that the construction personnel do not need to identify the direction to connect it in series to the bus, completely avoiding the failure caused by reverse connection, reducing the installation difficulty and error rate, and improving the efficiency and reliability of the project.

[0031] 2. Through the power supply control host's dynamic control and parallel reconstruction of the dual-port mode, the power supply path of the entire network can be intelligently changed after a fault occurs. Utilizing the bidirectional conduction characteristics of the non-polar isolator, power supply and communication can be quickly restored to equipment, including those in non-faulty sections, greatly reducing the scope of the fault's impact and improving the overall availability of the system.

[0032] 3. All isolators, acting as intelligent nodes, report their status to the host. The host then performs digital logic judgments based on the global network topology, enabling precise location of fault points.

[0033] 4. Combining the non-polarity structure of the bus isolator with the intelligent reconfiguration method of the system is crucial. Without this non-polarity design, the isolator would not be able to conduct when the current is reversed, and the system's power supply path reconfiguration and recovery mechanism would completely fail. Similarly, if there is only a non-polarity isolator without the system's intelligent reconfiguration strategy, its advantage is limited to ease of installation and cannot solve the problem of widespread paralysis after a fault. The combination of the two achieves a technical effect of 1+1>2. Attached Figure Description

[0034] Figure 1 This is a block diagram illustrating the application of the intelligent bus isolator of the present invention in a bus system;

[0035] Figure 2(a) is a circuit diagram of a bidirectional switching module and a control and communication module of a specific embodiment of the intelligent bus isolator of the present invention;

[0036] Figure 2(b) is a circuit diagram of a microcontroller in a specific embodiment of the intelligent bus isolator of the present invention;

[0037] Figure 2(c) is a circuit diagram of the power module of a specific embodiment of the intelligent bus isolator of the present invention. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and preferred embodiments. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0039] like Figure 1 As shown, a complete fire protection two-wire system includes a power supply control host ( Figure 1 The system comprises a bus network connected to the power supply control host (shown in the diagram), and multiple intelligent bus isolators connected in series within the bus network. Field devices are connected in parallel to various sections divided by multiple isolators. The power supply control host has a first port (composed of power supply terminal blocks 1 and 2), a second port (composed of power supply terminal blocks 3 and 4), and a parallel port switch (which can be connected in parallel via relays or other circuits) connecting the first and second ports. During normal operation, the power supply control host controls the first port to operate in power supply and communication mode, and controls the second port to operate in high-impedance detection mode. When a line fault or system communication logic abnormality is detected through the second port, the power supply control host controls the parallel port switch to close and switches the operating mode of the second port from high-impedance detection mode to power supply-communication mode. At this time, the first and second ports are connected in parallel, serving as the power supply access points for the bus network. After the first and second ports are connected in parallel, the power supply current will naturally be injected into the network from these two parallel points, and the feasible path will be automatically selected according to the network topology.

[0040] As shown in Figure 2(a), the bidirectional switch module consists of rectifier bridges DB1 and DB2 and MOSFETs Q11, Q12, Q13, and Q14.

[0041] The AC sides of DB1 and DB2 are connected to the two ends of the isolator's bus (BUSA_IN / BUSB_IN and BUSA_OUT / BUSB_OUT), respectively.

[0042] The sources of MOSFETs Q11 and Q12 are connected, and the sources of Q13 and Q14 are connected. The drains of Q11 and Q14 are connected to the positive output (+) of the input rectifier bridge DB1; the drains of Q12 and Q13 are connected to the positive output (+) of the output rectifier bridge DB2. The negative outputs (-) of both rectifier bridges are connected to ground (GND1). The microcontroller IC3 controls the gates of these four MOSFETs through a driver circuit to switch them on and off.

[0043] Regardless of whether the external two-wire power supply is from the input end to the output end (forward) or from the output end to the input end (reverse), when the current enters the isolator, it will first pass through the corresponding rectifier bridge (DB1 or DB2) and be rectified into a uniform DC direction inside.

[0044] When conduction is required, the microcontroller IC3 controls the four MOSFETs to conduct simultaneously. Due to the presence of the rectifier bridge, external AC or uncertain-direction current is converted to internal DC, and then output directionally through the controllable H-bridge, thus completely eliminating dependence on external wiring polarity and achieving polarity-free installation and bidirectional controllable conduction. Furthermore, it is precisely because of the bidirectional conduction characteristic of the polarity-free bus isolator that current can flow in reverse without hindrance.

[0045] The control and communication module is responsible for communicating with the upper-level host and executing instructions, including signal receiving circuits, signal transmitting circuits, and processing units.

[0046] The main function of the signal receiving circuit is to safely and reliably extract the digital communication code stream from the modulation bus signal, which is up to 24V. Resistors R94, R95, R98, and R99 form a high-impedance, high common-mode rejection differential attenuation network, which proportionally attenuates the high-voltage differential signal (between BUSA and BUSB) on the bus to a low-voltage range. Capacitors C1 and C20 are used to filter out high-frequency interference. The processed signal is read and decoded by the I / O port of the microcontroller IC3 to obtain the host's instructions (such as status query and on / off control commands).

[0047] The signal transmission circuit sends the isolator's status information (such as unique address, switch status, and fault flags) back to the host. The core of the circuit is a transistor Q8 controlled by a microcontroller IC3. When data needs to be transmitted, IC3 controls Q8 to turn on or off in a specific timing sequence. The on / off state of Q8 changes the load on the bus in the branch containing resistors R96 and R97, thus modulating the constant-amplitude 24V modulation signal from the host, producing a small voltage change. The host can demodulate the data transmitted by the isolator by detecting this controlled change in its output voltage. This load-modulated communication is a typical communication method for slave devices in a two-bus system.

[0048] It is important to note that the direct communication target of this isolator is the two-bus circuit at the system power supply end. The isolators do not communicate directly point-to-point; instead, they indirectly exchange and forward status information through the power supply bus circuit, which serves as the information hub.

[0049] The processing unit, centered around the microcontroller IC3, is responsible for running the firmware and coordinating all functions. This includes parsing instructions from the receiving circuit, controlling the switching of MOS bridge arms, generating status data frames to be transmitted, and managing local protection logic. The wiring relationships of the pins of the microcontroller IC3 are shown in Figure 2(b).

[0050] The local protection unit can be integrated into the microcontroller's firmware or external detection circuitry. The microcontroller IC3 can continuously monitor the voltage at the rectifier bridge output or the current in the MOSFET path via the ADC (Analog-to-Digital Converter) channel or a dedicated comparator. When the detected current value momentarily exceeds the set safety threshold (indicating a short circuit), the firmware will immediately (usually within microseconds) issue a command to shut down all MOSFETs, achieving rapid protection through a combination of software and hardware to prevent the fault from escalating.

[0051] The power supply module, as shown in Figure 2(c), is based on IC9 and provides a stable operating power supply for the bus isolator itself. Since the power supply module is a conventional circuit module, it will not be described in detail here.

[0052] The entire process of the system going from normal to failure and then to recovery is as follows:

[0053] 1. Normal state: The power supply control host (PSE) is powered on, and relay K1 connecting port 1 and port 2 is disconnected. Port 1 outputs modulated power to power communication for the entire network. Port 2 is set to high-impedance input and only monitors its line voltage.

[0054] 2. Fault Occurrence and Initial Hardware Isolation: Assume a short circuit occurs at the device on the branch where port 1 is located. The isolator ISO_B2, which is closest to the fault point, detects the overcurrent, and its internal MOSFETs (Q11-Q14) are quickly turned off, achieving millisecond-level hardware protection.

[0055] 3. System Intelligent Reconfiguration: The PSE detects an abnormal voltage drop through port 2 and determines that a fault has occurred. The PSE immediately closes relay K1 and switches port 2 to the same power supply-communication mode as port 1. At this time, port 1 and port 2 are connected in parallel. Since ISO_B2 is disconnected, current cannot flow out of port 1 in its original direction. After the current flows out from the parallel connection point, due to the non-polarity characteristic of the isolator, it can flow in reverse into the upstream line of ISO_B2, restoring power supply and communication to the upstream device of ISO_B2.

[0056] 4. Centralized Diagnosis and Precise Location: The PSE sends query frames via the bus. Isolators ISO_A1, ISO_A2, and ISO_B1 reply with their on / off status and address, while ISO_B2 replies with its off / open status and address. Based on the stored topology (...ISO_B1 → ISO_B2 → ...) and the logic of ISO_B2 being off and its neighbors being on, the PSE accurately determines that the fault is located downstream of ISO_B2.

[0057] 5. Final Software Isolation: The PSE issues a command to confirm that ISO_B2 remains disconnected. The fault is strictly isolated within the minimum range downstream of ISO_B2.

[0058] 6. System Recovery: After the system is isolated from the fault, maintenance personnel can perform rapid repairs based on this precise information. Bus voltage and communication in the non-faulty section return to normal, and connected devices can continue to operate. Once the fault is cleared, the control module can re-enable the switching unit and connect the isolated section by using a system reset command or by automatically detecting that line parameters have returned to normal.

[0059] The above description is only a specific embodiment of the present invention. Various examples and illustrations do not constitute a limitation on the substantive content of the present invention. Those skilled in the art can make modifications or variations to the above-described specific embodiments after reading the specification without departing from the substance and scope of the invention.

Claims

1. A fire protection two bus system, characterized by: The application relates to a power supply control host, a bus network and a plurality of intelligent bus isolators. The power supply control host is provided with a first port, a second port and a port parallel switch connected between the first port and the second port; in normal operation, the power supply control host controls the first port to work in a power supply and communication mode and controls the second port to work in a high-resistance detection mode; The first port and the second port are respectively connected to the bus network; The intelligent bus isolators are connected in series in the bus network; the intelligent bus isolators comprise a bidirectional switch module and a control and communication module; the bidirectional switch module comprises a rectifier bridge and at least one pair of back-to-back field effect transistors connected to an output end of the rectifier bridge; the alternating current side of the rectifier bridge is connected to bus connection ends of the isolators, so that the isolators do not need to distinguish the current input direction when being connected to the bus; the control and communication module is connected to a control end of the bidirectional switch module; the control and communication module controls the on-off of the bidirectional switch module and realizes bidirectional data communication with an external controller; When a fault occurs, the power supply control host receives a fault triggering condition, controls the port parallel switch to be closed, makes the first port and the second port parallel to each other as a power supply access point of the bus network, acquires state information of the intelligent bus isolators through communication with the intelligent bus isolators and determines a fault position according to pre-stored network topological information.

2. A fire protection two bus system as defined in claim 1 wherein: The fault triggering condition is that the second port detects line short circuit, open circuit or communication interruption of the bus network.

3. A fire protection two bus system as defined in claim 1 wherein: The power supply control host records the connection sequence of each intelligent bus isolator through communication to form the network topological information during system initialization.

4. A fire protection two bus system as defined in claim 1 wherein: After the first port and the second port are parallel to each other, the intelligent bus isolators have bidirectional conduction characteristics and can flow through reverse current generated by power supply path reconstruction to restore power supply for devices upstream of the fault isolation point.

5. A fire protection two bus system as defined in claim 1 wherein: The control and communication module comprises a microcontroller, a signal receiving circuit and a signal sending circuit; the signal receiving circuit is used for coupling and demodulating communication signals from an upper host from the bus; the signal sending circuit is used for sending state information of the isolators to the bus under the control of the microcontroller.

6. A fire protection two bus system as defined in claim 1 wherein: A local protection unit is further included; the local protection unit monitors electrical parameters of a passage where the bidirectional switch module is located and triggers the bidirectional switch module to be turned off when the electrical parameters exceed a preset threshold.

7. A method of fault isolation for a fire protection two bus system as claimed in any one of claims 1 to 6, characterised by: The application further comprises the following steps: S1, normal power supply: the first port supplies power and communicates to the bus network, and the second port is in a detection state; S2, fault response and reconstruction: when the second port detects that the connection line thereof is faulty, the power supply control host closes the parallel switch and switches the second port to the power supply and communication mode; S3, path reconstruction and recovery: the first port and the second port supply power to the bus network in parallel, and the bidirectional conduction characteristics of the intelligent bus isolators make current flow along the reconstructed path to restore power supply and communication for non-fault sections in the network. S4, positioning and isolation: the power supply control host communicates with each non-polarity intelligent bus isolator to obtain its state, combines with network topology to locate the fault point, and controls the corresponding isolator to perform isolation.

8. A method of fault isolation as claimed in claim 7, characterized in that: Before the step S2, the intelligent isolator closest to the fault point detects an overcurrent or short-circuit state, triggers the turn-off of the bidirectional switch module, and realizes fast hardware protection.

9. A method of fault isolation as claimed in claim 7, characterized in that: After the step S4, the method further comprises the steps of: S5, when the system detects that the fault has been cleared and the line parameters return to normal, the control of the intelligent bus isolator which has been disconnected automatically restores the conduction state of the switch unit thereof.

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