Surge protection circuit and differential bus transceiver system

Abstract

The utility model discloses a surge protection circuit and a differential bus transceiver system. The surge protection circuit comprises a gas discharge tube, a transient voltage suppressor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode and a sixth diode. Wherein the transient voltage suppressor, the first diode, the second diode, the third diode, the fourth diode, the fifth diode and the sixth diode are used for clamping surge voltage in the forms of differential mode interference voltage and common mode interference voltage so as to ensure that the differential bus transceiver is not damaged by high-voltage surge; and the gas discharge tube is used for releasing the energy of the surge voltage and reducing the voltage residual quantity to a relatively low level, so that the differential bus transceiver is prevented from being impacted by the high-energy transient voltage when the surge occurs. According to the technical scheme disclosed by the utility model, differential mode protection and common mode protection can be carried out on the differential bus transceiver, and the protection capability of the differential bus transceiver on high-voltage surge is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit protection, in particular to a surge protection circuit and a differential bus transceiver system. Background Art

[0002] With the rapid development of new energy technologies, energy storage devices are increasingly being used in power systems. As an important communication component of energy storage devices, the operation stability of differential bus transceivers is related to whether the energy storage devices can operate stably. Here, the differential bus transceiver communicates with external communication nodes based on differential signals through two ports, the high-level interactive end and the low-level interactive end.

[0003] In reality, when the power grid system where the differential bus transceiver is located is struck by lightning, a power grid failure occurs in the power grid system where the differential bus transceiver is located, or a large power load is suddenly added, surge phenomena will occur, causing extremely high voltage and current shocks to the differential bus transceiver. These high-energy pulses will cause serious damage to the differential bus transceiver, thereby affecting the stable operation of the power system.

[0004] At present, the surge protection method for differential bus transceivers is mostly achieved by setting a protection circuit for the differential bus transceiver. The existing protection circuit includes four diodes and a high-power bidirectional transient voltage suppressor, which uses the unidirectional conduction characteristics of the diode to ensure that the differential bus transceiver is surge protected when a surge occurs in a fixed direction. However, when a surge occurs, the protection circuit can only ensure that the voltage between the high-level interactive end and the low-level interactive end is clamped at a safe voltage value, but has no protection effect on the bus voltage to the ground of the bus where the high-level interactive end is located and the bus voltage to the ground of the bus where the low-level interactive end is located. As a result, the existing protection circuit can only perform differential mode protection on the differential bus transceiver, and cannot perform common mode protection on the differential bus transceiver, resulting in the differential bus transceiver's weak protection ability against high voltage surges. Utility Model Content

[0005] In view of this, the utility model provides a surge protection circuit and a differential bus transceiver system, the main purpose of which is to solve the technical problem that the current protection circuit can only perform differential mode protection on the differential bus transceiver when a surge occurs, but cannot perform common mode protection on the differential bus transceiver.

[0006] To achieve the above object, the utility model first provides a surge protection circuit for providing surge protection for a differential bus transceiver, the surge protection circuit comprising a gas discharge tube, a transient voltage suppressor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode and a sixth diode;

[0007] The anode terminal of the first diode is used to connect to the high-level interactive terminal of the differential bus transceiver, the cathode terminal of the first diode is respectively connected to the first access terminal of the transient voltage suppressor and the cathode terminal of the second diode, and the anode terminal of the second diode is used to connect to the low-level interactive terminal of the differential bus transceiver;

[0008] The cathode terminal of the third diode is connected to the anode terminal of the first diode, the anode terminal of the third diode is respectively connected to the second access terminal of the transient voltage suppressor and the anode terminal of the fourth diode, and the cathode terminal of the fourth diode is connected to the anode terminal of the second diode;

[0009] The cathode terminal of the fifth diode is connected to the cathode terminal of the first diode, the anode terminal of the fifth diode is grounded, the anode terminal of the sixth diode is connected to the anode terminal of the third diode, and the cathode terminal of the sixth diode is grounded;

[0010] The first access end of the gas discharge tube is connected to the cathode end of the third diode, the second access end of the gas discharge tube is connected to the cathode end of the fourth diode, the discharge end of the gas discharge tube is grounded, a high-level bus end is led out between the first access end of the gas discharge tube and the cathode end of the third diode, which is used to connect to the high-level signal bus end of an external communication node, and a low-level bus end is led out between the second access end of the gas discharge tube and the cathode end of the fourth diode, which is used to connect to the low-level signal bus end of the communication node.

[0011] In one embodiment of the utility model, the surge protection circuit also includes a first current limiting resistor and a second current limiting resistor; the first current limiting resistor is connected in series between the cathode end of the third diode and the first access end of the gas discharge tube; the second current limiting resistor is connected in series between the cathode end of the fourth diode and the second access end of the gas discharge tube.

[0012] In one embodiment of the utility model, the anode end of the fifth diode is connected to the cathode end of the sixth diode and grounded; the surge protection circuit also includes an electrostatic protection resistor; the first end of the electrostatic protection resistor is connected to the cathode end of the sixth diode, and the second end of the electrostatic protection resistor is connected to the discharge end of the gas discharge tube and the connection end is grounded.

[0013] In one embodiment of the utility model, the surge protection circuit also includes a high-frequency interference filtering capacitor; the first end of the high-frequency interference filtering capacitor is connected to the first end of the electrostatic protection resistor, and the second end of the high-frequency interference filtering capacitor is connected to the second end of the electrostatic protection resistor.

[0014] In one embodiment of the utility model, the surge protection circuit also includes a relay, a power supply and a surge alarm; the first end of the relay coil of the relay is connected to the discharge end of the gas discharge tube, and the second end of the relay coil is grounded; the first end of the normally open contact of the relay is connected to the power supply end of the power supply, and the second end of the normally open contact is connected to the alarm access end of the surge alarm, wherein the surge alarm issues an alarm prompt message when receiving a voltage from the alarm access end.

[0015] In addition, to achieve the above object, the utility model also proposes a differential bus transceiver system, the differential bus transceiver system includes a differential bus transceiver and the surge protection circuit as described above;

[0016] The high-level interactive end of the differential bus transceiver is connected to the anode end of the first diode of the surge protection circuit, and the low-level interactive end of the differential bus transceiver is connected to the anode end of the second diode of the surge protection circuit;

[0017] The ground terminal of the differential bus transceiver is grounded.

[0018] In one embodiment of the utility model, the differential bus transceiver system also includes a common-mode inductor; the first pin of the common-mode inductor is connected to the high-level interaction end of the differential bus transceiver, and the second pin of the common-mode inductor is connected to the anode end of the first diode; the third pin of the common-mode inductor is connected to the low-level interaction end of the differential bus transceiver, and the fourth pin of the common-mode inductor is connected to the anode end of the second diode; wherein the first pin of the common-mode inductor and the second pin of the common-mode inductor are directly connected in the common-mode inductor, and the third pin of the common-mode inductor and the fourth pin of the common-mode inductor are directly connected in the common-mode inductor.

[0019] In one embodiment of the utility model, the differential bus transceiver system also includes a high-frequency interference elimination circuit, which includes a first terminal resistor, a second terminal resistor and a filter capacitor; the first end of the first terminal resistor is connected to the high-level interaction end of the differential bus transceiver, the first end of the second terminal resistor is connected to the low-level interaction end of the differential bus transceiver, the second end of the first terminal resistor and the second end of the second terminal resistor are connected to the first end of the filter capacitor, and the second end of the filter capacitor is connected to the ground end of the differential bus transceiver.

[0020] In one embodiment of the utility model, the differential bus transceiver system is arranged in a metal casing, and the ground end of the differential bus transceiver, the anode end of the fifth diode and the cathode end of the sixth diode are connected and then grounded; the discharge end of the gas discharge tube is connected to the chassis ground of the metal casing so that the discharge end of the gas discharge tube is grounded.

[0021] In one embodiment of the present invention, the differential bus transceiver is an RS485 transceiver or a controller area network transceiver.

[0022] The utility model provides a surge protection circuit and a differential bus transceiver system. When a surge caused by lightning or other reasons occurs, for a positive common-mode interference voltage flowing in from a high-level bus terminal, a first diode, a transient voltage suppressor (TVS) and a sixth diode are turned on at the first time to form a voltage clamping loop, thereby limiting the bus pin voltage of the differential bus transceiver within a safe range; further, for a negative common-mode interference voltage flowing in from a high-level bus terminal, a third diode, a transient voltage suppressor and a fifth diode are turned on at the first time to form a voltage clamping loop, thereby limiting the bus pin voltage of the differential bus transceiver within a safe range.

[0023] Furthermore, in response to the positive common-mode interference voltage flowing in from the low-level bus terminal, the second diode, the transient voltage suppressor and the sixth diode are turned on at the first time to form a voltage clamping loop, thereby limiting the bus pin voltage of the differential bus transceiver within a safe range; further, in response to the negative common-mode interference voltage flowing in from the low-level bus terminal, the fourth diode, the transient voltage suppressor and the fifth diode are turned on at the first time to form a voltage clamping loop, thereby limiting the bus pin voltage of the differential bus transceiver within a safe range.

[0024] Furthermore, the gas discharge tube (GDT) has the slowest response and turns on after a period of time after the surge occurs, releasing the energy of the surge and reducing the residual voltage of the surge to a lower level.

[0025] In contrast, for the differential mode interference voltage flowing in from the high-level bus end and the low-level bus end, if the voltage flowing in from the high-level bus end is higher than the voltage flowing in from the low-level bus end, the first diode, the transient voltage suppressor and the fourth diode are turned on, and the voltage between the high-level interactive end and the low-level interactive end of the differential bus transceiver is clamped to prevent the differential bus transceiver from being damaged by the high voltage; if the voltage flowing in from the low-level bus end is higher than the voltage flowing in from the high-level bus end, the second diode, the transient voltage suppressor and the third diode are turned on, and the voltage between the low-level interactive end and the high-level interactive end of the differential bus transceiver is clamped to prevent the differential bus transceiver from being damaged by the high voltage. Furthermore, the gas discharge tube has the slowest response and is turned on after a period of time after the surge occurs, releasing the energy of the surge and reducing the voltage residual of the surge to a lower level. The technical solution disclosed in the utility model can perform differential mode protection and common mode protection on the differential bus transceiver, thereby improving the protection capability of the differential bus transceiver against high voltage surges.

[0026] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0028] Figure 1 One of the structural schematic diagrams of a surge protection circuit provided by an embodiment of the utility model is shown;

[0029] Figure 2 A second schematic diagram of the structure of a surge protection circuit provided by an embodiment of the utility model is shown;

[0030] Figure 3 A third schematic diagram of the structure of a surge protection circuit provided by an embodiment of the utility model is shown;

[0031] Figure 4 One of the structural schematic diagrams of a differential bus transceiver system provided by an embodiment of the utility model is shown;

[0032] Figure 5 A second structural schematic diagram of a differential bus transceiver system provided by an embodiment of the utility model is shown;

[0033] Figure 6A third structural diagram of a differential bus transceiver system provided by an embodiment of the utility model is shown;

[0034] Figure 7 A fourth structural schematic diagram of a differential bus transceiver system provided by an embodiment of the utility model is shown. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0036] In order to further explain the technical means and effects adopted by the utility model to achieve the predetermined utility model purpose, the specific implementation methods, structures, features and effects of the utility model application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0037] Combine the following Figures 1 to 7 A surge protection circuit and a differential bus transceiver system according to some embodiments of the present invention are described.

[0038] like Figure 1 As shown, a surge protection circuit proposed in one embodiment of the utility model is used to provide surge protection for a differential bus transceiver, wherein the differential bus transceiver outputs or receives a differential signal through a high-level interactive terminal H and a low-level interactive terminal L to achieve data output and reception. Specifically, the type of the differential bus transceiver can be an RS485 transceiver and a controller area network (CAN) transceiver.

[0039] Further, the surge protection circuit includes a gas discharge tube, a transient voltage suppressor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode and a sixth diode. Here, the conduction voltage of the transient voltage suppressor is higher than the maximum amplitude of the differential signal output or received by the differential bus transceiver, but cannot exceed the maximum DC withstand voltage of the differential bus transceiver pin (including the high level interactive terminal H and the low level interactive terminal L).

[0040] Specifically, the anode end of the first diode is used to connect to the high-level interaction end H of the differential bus transceiver, the cathode end of the first diode is respectively connected to the first access end of the transient voltage suppressor and the cathode end of the second diode, and the anode end of the second diode is used to connect to the low-level interaction end L of the differential bus transceiver.

[0041] Furthermore, the cathode terminal of the third diode is connected to the anode terminal of the first diode, the anode terminal of the third diode is respectively connected to the second access terminal of the transient voltage suppressor and the anode terminal of the fourth diode, and the cathode terminal of the fourth diode is connected to the anode terminal of the second diode.

[0042] Further, the cathode terminal of the fifth diode is connected to the cathode terminal of the first diode, the anode terminal of the fifth diode is grounded, the anode terminal of the sixth diode is connected to the anode terminal of the third diode, and the cathode terminal of the sixth diode is grounded.

[0043] Furthermore, the first access terminal of the gas discharge tube is connected to the cathode terminal of the third diode, the second access terminal of the gas discharge tube is connected to the cathode terminal of the fourth diode, the discharge terminal of the gas discharge tube is grounded, a high-level bus terminal extends between the first access terminal of the gas discharge tube and the cathode terminal of the third diode, which is used to connect to the high-level signal bus terminal of an external communication node (not shown in the figure), and a low-level bus terminal extends between the second access terminal of the gas discharge tube and the cathode terminal of the fourth diode, which is used to connect to the low-level signal bus terminal of an external communication node. Here, the communication node can be an external power system device that communicates with a differential bus transceiver through differential signals.

[0044] Here, the reverse withstand voltage of the first diode, the second diode, the third diode, the fourth diode, the fifth diode and the sixth diode should be much higher than the maximum conduction voltage of the transient voltage suppressor.

[0045] In actual use, the high-level bus end of the surge protection circuit can be connected to the high-level signal bus end of the communication node, the low-level bus end of the surge protection circuit can be connected to the low-level signal bus end of the communication node, and the anode end of the first diode can be connected to the high-level interaction end H of the differential bus transceiver, and the anode end of the second diode can be connected to the low-level interaction end L of the differential bus transceiver, so that the high-level interaction end H of the differential bus transceiver is connected to the high-level signal bus end of the communication node, and the low-level interaction end L of the differential bus transceiver is connected to the low-level signal bus end of the communication node, so that the differential bus transceiver can communicate data with the communication node based on differential signals.

[0046] Furthermore, when a surge caused by lightning strike or the like occurs and triggers the common-mode protection of the surge protection circuit, the first diode, the transient voltage suppressor, and the sixth diode are turned on at the first time for the positive common-mode interference voltage flowing in from the high-level bus end, forming a voltage clamping loop to conduct a small amount of energy to the ground, thereby limiting the bus pin voltage of the differential bus transceiver within a safe range; conversely, for the negative common-mode interference voltage flowing in from the high-level bus end, the third diode, the transient voltage suppressor, and the fifth diode are turned on at the first time for the negative common-mode interference voltage flowing in from the high-level bus end, forming a voltage clamping loop to conduct a small amount of energy to the ground, thereby limiting the bus pin voltage of the differential bus transceiver within a safe range.

[0047] Furthermore, in response to the positive common-mode interference voltage surging from the low-level bus end, the second diode, the transient voltage suppressor and the sixth diode are turned on at the first time to form a voltage clamping loop, which conducts a small amount of energy to the ground, and limits the bus pin voltage of the differential bus transceiver within a safe range; conversely, in response to the negative common-mode interference voltage surging from the low-level bus end, the fourth diode, the transient voltage suppressor and the fifth diode are turned on at the first time to form a voltage clamping loop, which conducts a small amount of energy to the ground, and limits the bus pin voltage of the differential bus transceiver within a safe range.

[0048] Furthermore, the gas discharge tube (GDT) has the slowest response and turns on after a period of time after the surge occurs, releasing most of the surge energy to reduce the surge voltage residue to a lower level.

[0049] In contrast, when a surge caused by lightning or other reasons occurs and triggers the differential mode protection of the circuit, for the differential mode interference voltage flowing in from the high-level bus end and the low-level bus end, if the voltage flowing in from the high-level bus end is higher than the voltage flowing in from the low-level bus end, the first diode, the transient voltage suppressor and the fourth diode are turned on, so that the voltage between the high-level interactive end and the low-level interactive end of the differential bus transceiver is clamped, preventing the differential bus transceiver from being damaged by the high voltage; further, if the voltage flowing in from the low-level bus end is higher than the voltage flowing in from the high-level bus end, the second diode, the transient voltage suppressor and the third diode are turned on, and the voltage between the low-level interactive end and the high-level interactive end of the differential bus transceiver is clamped, preventing the differential bus transceiver from being damaged by the high voltage. Furthermore, the gas discharge tube has the slowest response and is turned on after a period of time after the surge occurs, releasing the energy of the surge and reducing the voltage residual of the surge to a lower level.

[0050] A surge protection circuit proposed in an embodiment of the utility model has low hardware cost and can perform differential mode protection and common mode protection on a differential bus transceiver when a surge caused by lightning strike or the like occurs, thereby improving the protection capability of the differential bus transceiver against high voltage surges.

[0051] In one embodiment, Figure 2 As shown, the surge protection circuit also includes a first current limiting resistor and a second current limiting resistor; wherein the first current limiting resistor and the second current limiting resistor are used to limit the magnitude of the current flowing through the transient voltage suppressor, to prevent the current flowing through the transient voltage suppressor from being too large when a surge occurs, and to prevent the transient voltage suppressor from being damaged due to excessive power. Here, when selecting the first current limiting resistor and the second current limiting resistor, the resistance values ​​of the first current limiting resistor and the second current limiting resistor should be avoided to be too large, so as to avoid the differential signal amplitude of the differential bus transceiver from decreasing. The resistance values ​​of the first current limiting resistor and the second current limiting resistor are generally recommended to be 10 ohms or less, such as 4.7 ohms.

[0052] Specifically, the first current limiting resistor is connected in series between the cathode end of the third diode and the first access end of the gas discharge tube, the first end of the first current limiting resistor is connected to the cathode end of the third diode, and the second end of the first current limiting resistor is connected to the first access end of the gas discharge tube; the second current limiting resistor is connected in series between the cathode end of the fourth diode and the second access end of the gas discharge tube, the first end of the second current limiting resistor is connected to the cathode end of the fourth diode, and the second end of the second current limiting resistor is connected to the second access end of the gas discharge tube. Furthermore, the anode end of the fifth diode, the cathode end of the sixth diode, and the discharge end of the gas discharge tube can be connected, and the connection end formed after the connection is grounded.

[0053] The embodiments provided in the present application can perform current limiting protection on a transient voltage suppressor based on a first current limiting resistor and a second current limiting resistor, thereby preventing the transient voltage suppressor from being damaged and failing due to excessive power when a surge occurs, thereby improving the reliability of the surge protection circuit.

[0054] In one embodiment, Figure 3 As shown, the anode terminal of the fifth diode is connected to the cathode terminal of the sixth diode; the surge protection circuit also includes an electrostatic protection resistor. Specifically, the first end of the electrostatic protection resistor is connected to the cathode terminal of the sixth diode, and the second end of the electrostatic protection resistor is connected to the discharge terminal of the gas discharge tube and then connected to the ground. The resistance value of the electrostatic protection resistor can be 1 megohm. Here, the anode terminal of the fifth diode can be connected to the cathode terminal of the sixth diode and then connected to the first ground GND1, and the second end of the electrostatic protection resistor can be connected to the power ground PGND after being connected to the discharge terminal of the gas discharge tube.

[0055] The embodiment provided in the present application sets an electrostatic protection resistor in the surge protection circuit, which can prevent the surge protection circuit and the differential bus transceiver from being damaged when electrostatic discharge (ESD) occurs in the surge protection circuit, thereby improving the reliability of the surge protection circuit.

[0056] In one embodiment, Figure 3 As shown, the surge protection circuit also includes a high-frequency interference filtering capacitor, wherein the high-frequency interference filtering capacitor can be 1 nanofarad. Specifically, the first end of the high-frequency interference filtering capacitor is connected to the first end of the electrostatic protection resistor, and the second end of the high-frequency interference filtering capacitor is connected to the second end of the electrostatic protection resistor.

[0057] Here, based on the perspective of electromagnetic immunity, the high-frequency interference filtering capacitor is to reduce the influence of the possible high-frequency interference signal with the ground level as a reference on the surge protection circuit under the premise that the protective grounding of the surge protection circuit is well connected to the earth, and can suppress the transient common-mode voltage difference between the surge protection circuit and the interference source. In the embodiment provided by the present application, a high-frequency interference filtering capacitor is set in the surge protection circuit to avoid the influence of the high-frequency interference signal appearing in the circuit during operation on the circuit, suppress the transient common-mode voltage difference between the surge protection circuit and the possible interference source, and thus improve the reliability of the surge protection circuit. Here, in order to effectively eliminate common-mode interference, the earth or protective ground must be used as a discharge circuit for the surge voltage in the form of common-mode interference voltage, and the surge protection circuit must ensure reliable grounding, otherwise the common-mode protection part will not be able to find the return path, resulting in the surge protection circuit being unable to work normally, which may cause damage to the upper chip or circuit.

[0058] In one embodiment, the surge protection circuit further includes a relay, a power supply, and a surge alarm; specifically, the first end of the relay coil of the relay is connected to the discharge end of the gas discharge tube, and the second end of the relay coil is grounded. Here, the second end of the relay coil can be connected to the second end of the electrostatic protection resistor, so that the gas discharge tube is grounded through the relay coil. Further, the first end of the normally open contact of the relay is connected to the power supply end of the power supply, and the second end of the normally open contact is connected to the alarm access end of the surge alarm, wherein the surge alarm issues an alarm prompt message when receiving a voltage from the alarm access end; here, the power supply end of the power supply is used to output voltage, the surge alarm can be an audible and visual alarm set in the monitoring room or control room of the power system, and the power supply can be a voltage source that outputs voltage to the outside.

[0059] Furthermore, when a surge occurs in the surge protection circuit, the gas discharge tube discharges to the outside through its discharge end. At this time, the relay coil of the relay is energized, causing the normally open contact of the relay to be turned on, so that the power supply can output voltage to the surge alarm through the relay, and then the surge alarm obtains voltage from the alarm access end, causing the surge alarm to issue an alarm prompt message.

[0060] The embodiment provided by the present application can send an alarm message to the staff in the monitoring room or control room of the power system when a surge occurs in the surge protection circuit, so that the relevant staff can be informed that a surge has occurred in the system where the differential bus transceiver is located, and respond and process, thereby improving the monitoring and alarm capabilities of the surge protection circuit for surge phenomena.

[0061] A surge protection circuit proposed in an embodiment of the utility model can maintain an overall differential capacitance of about 10pF, so that the circuit can provide good surge protection without interfering with the communication of the differential bus transceiver. In this surge protection circuit, a gas discharge tube with a flow rate of 500A, a start voltage of 90V, and a package of 1206 can be selected; further, if the design space permits, a gas discharge tube with a higher flow rate can be selected to improve the protection performance of the circuit. When a surge occurs due to lightning strikes and other reasons, it can ensure that the transient voltage suppressor will not be damaged by large currents, and the differential bus transceiver can be stably protected by differential mode and common mode, thereby improving the protection capability of the differential bus transceiver against high voltage surges. The surge protection circuit can also immediately remind relevant staff of surge accidents when a surge occurs in the system where the differential bus transceiver is located, thereby improving the abnormal monitoring capability of the differential bus transceiver.

[0062] On the other hand, an embodiment of the present utility model provides a differential bus transceiver system, such as Figure 4 As shown, the differential bus transceiver system includes a differential bus transceiver and the surge protection circuit as described above.

[0063] Specifically, the high-level interactive terminal H of the differential bus transceiver is connected to the anode terminal of the first diode of the surge protection circuit, and the low-level interactive terminal L of the differential bus transceiver is connected to the anode terminal of the second diode of the surge protection circuit; further, the ground terminal GND of the differential bus transceiver is grounded. The differential bus transceiver system provided by the present application can communicate with external communication nodes through the differential bus transceiver, and can effectively protect against surge phenomena, and has good operating stability.

[0064] In an optional embodiment, if Figure 4As shown, the differential bus transceiver system also includes a common-mode inductor; specifically, a first pin of the common-mode inductor is connected to a high-level interaction terminal H of the differential bus transceiver, and a second pin of the common-mode inductor is connected to an anode terminal of the first diode; further, a third pin of the common-mode inductor is connected to a low-level interaction terminal L of the differential bus transceiver, and a fourth pin of the common-mode inductor is connected to an anode terminal of the second diode.

[0065] The first pin of the common-mode inductor is directly connected to the second pin of the common-mode inductor in the common-mode inductor, and the third pin of the common-mode inductor is directly connected to the fourth pin of the common-mode inductor in the common-mode inductor. The embodiment provided by the present application can eliminate common-mode interference in a differential bus transceiver system based on the common-mode inductor, thereby improving the operating stability of the differential bus transceiver system.

[0066] In an optional embodiment, if Figure 5 As shown, the differential bus transceiver system further includes a high-frequency interference elimination circuit, and the high-frequency interference elimination circuit includes a first terminal resistor R1, a second terminal resistor R2 and a filter capacitor C1.

[0067] Specifically, the first end of the first terminal resistor R1 is connected to the high-level interactive end H of the differential bus transceiver, the first end of the second terminal resistor R2 is connected to the low-level interactive end L of the differential bus transceiver, the second end of the first terminal resistor R1 and the second end of the second terminal resistor R2 are connected to the first end of the filter capacitor C1, and the second end of the filter capacitor C1 is connected to the ground terminal GND of the differential bus transceiver. Here, the second end of the filter capacitor C1, the ground terminal GND of the differential bus transceiver, the anode end of the fifth diode, and the cathode end of the sixth diode can be connected together and then grounded uniformly.

[0068] Here, the first terminal resistor R1 and the second terminal resistor R2 can be used as terminal resistors of the differential bus transceiver to enhance the signal strength of the differential signal, and the filter capacitor C1 can filter the differential signal received and output by the differential bus transceiver to eliminate high-frequency interference in the differential signal.

[0069] Furthermore, the differential bus transceiver may be a controller area network (CAN) transceiver, specifically, Figure 6As shown, the high-level differential signal transceiver terminal CANH of the CAN transceiver is connected to the first pin of the common-mode inductor as the high-level interactive terminal of the differential bus transceiver, the low-level differential signal transceiver terminal CANL of the CAN transceiver is connected to the third pin of the common-mode inductor as the low-level interactive terminal of the differential bus transceiver, and the CAN transceiver ground terminal GNDa of the CAN transceiver is connected to the second end of the filter capacitor C1 as the ground terminal of the differential bus transceiver.

[0070] Furthermore, the differential bus transceiver may be an RS485 transceiver, specifically, Figure 7 As shown, the high-level differential signal terminal RS485A of the RS485 transceiver is connected to the first pin of the common-mode inductor as the high-level interactive terminal of the differential bus transceiver, the low-level differential signal terminal RS485B of the RS485 transceiver is connected to the third pin of the common-mode inductor as the low-level interactive terminal of the differential bus transceiver, and the transceiver ground terminal GNDb of the RS485 transceiver is connected to the second end of the filter capacitor C1 as the ground terminal of the differential bus transceiver.

[0071] The embodiments provided in the present application can eliminate high-frequency interference in the differential signals received and output by the differential bus transceiver based on the high-frequency interference elimination circuit, and can significantly improve the signal quality of the differential signals received and output by the differential bus transceiver, thereby improving the communication quality of the differential bus transceiver.

[0072] In one embodiment, the differential bus transceiver system is disposed in a metal casing, and the ground end of the differential bus transceiver, the anode end of the fifth diode, and the cathode end of the sixth diode are connected and then grounded; the discharge end of the gas discharge tube is connected to the chassis ground of the metal casing so that the discharge end of the gas discharge tube is grounded.

[0073] Specifically, the differential bus transceiver and the surge protection circuit can be arranged inside a metal box, and the ground terminal of the differential bus transceiver, the anode terminal of the fifth diode, and the cathode terminal of the sixth diode are connected and grounded. The discharge end of the gas discharge tube is connected to the chassis ground of the metal shell of the box body to achieve grounding through the chassis ground. The embodiment provided by the present application can ensure the reliable grounding of the differential bus transceiver and the surge protection circuit, so that the interference signal generated when a surge occurs can be released in time through the discharge circuit, thereby improving the surge protection capability of the differential bus transceiver system.

[0074] The above-mentioned embodiments only express several implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A surge protection circuit for providing surge protection for a differential bus transceiver, characterized in that: The surge protection circuit includes a gas discharge tube, a transient voltage suppressor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode and a sixth diode; The anode terminal of the first diode is used to connect to the high-level interactive terminal of the differential bus transceiver, the cathode terminal of the first diode is respectively connected to the first access terminal of the transient voltage suppressor and the cathode terminal of the second diode, and the anode terminal of the second diode is used to connect to the low-level interactive terminal of the differential bus transceiver; The cathode terminal of the third diode is connected to the anode terminal of the first diode, the anode terminal of the third diode is respectively connected to the second access terminal of the transient voltage suppressor and the anode terminal of the fourth diode, and the cathode terminal of the fourth diode is connected to the anode terminal of the second diode; The cathode terminal of the fifth diode is connected to the cathode terminal of the first diode, the anode terminal of the fifth diode is grounded, the anode terminal of the sixth diode is connected to the anode terminal of the third diode, and the cathode terminal of the sixth diode is grounded; The first access end of the gas discharge tube is connected to the cathode end of the third diode, the second access end of the gas discharge tube is connected to the cathode end of the fourth diode, the discharge end of the gas discharge tube is grounded, a high-level bus end is led out between the first access end of the gas discharge tube and the cathode end of the third diode, which is used to connect to the high-level signal bus end of an external communication node, and a low-level bus end is led out between the second access end of the gas discharge tube and the cathode end of the fourth diode, which is used to connect to the low-level signal bus end of the communication node.

2. The surge protection circuit according to claim 1, characterized in that: The surge protection circuit also includes a first current limiting resistor and a second current limiting resistor; The first current limiting resistor is connected in series between the cathode end of the third diode and the first access end of the gas discharge tube; The second current limiting resistor is connected in series between the cathode end of the fourth diode and the second access end of the gas discharge tube.

3. The surge protection circuit according to claim 1, characterized in that: The anode end of the fifth diode is connected to the cathode end of the sixth diode and is grounded; the surge protection circuit also includes an electrostatic protection resistor; The first end of the electrostatic protection resistor is connected to the cathode end of the sixth diode, and the second end of the electrostatic protection resistor is connected to the discharge end of the gas discharge tube, and the connection end is grounded.

4. The surge protection circuit according to claim 3, characterized in that: The surge protection circuit also includes a high-frequency interference filtering capacitor; The first end of the high-frequency interference filtering capacitor is connected to the first end of the electrostatic protection resistor, and the second end of the high-frequency interference filtering capacitor is connected to the second end of the electrostatic protection resistor.

5. The surge protection circuit according to claim 1, characterized in that: The surge protection circuit also includes a relay, a power supply and a surge alarm; A first end of the relay coil of the relay is connected to the discharge end of the gas discharge tube, and a second end of the relay coil is grounded; The first end of the normally open contact of the relay is connected to the power supply end of the power supply, and the second end of the normally open contact is connected to the alarm access end of the surge alarm, wherein the surge alarm issues an alarm prompt message when receiving voltage from the alarm access end.

6. A differential bus transceiver system, characterized in that: The differential bus transceiver system comprises a differential bus transceiver and a surge protection circuit as claimed in any one of claims 1 to 5; The high-level interactive end of the differential bus transceiver is connected to the anode end of the first diode of the surge protection circuit, and the low-level interactive end of the differential bus transceiver is connected to the anode end of the second diode of the surge protection circuit; The ground terminal of the differential bus transceiver is grounded.

7. The differential bus transceiver system according to claim 6, characterized in that: The differential bus transceiver system further includes a common mode inductor; The first pin of the common-mode inductor is connected to the high-level interactive terminal of the differential bus transceiver, and the second pin of the common-mode inductor is connected to the anode terminal of the first diode; The third pin of the common mode inductor is connected to the low level interaction end of the differential bus transceiver, and the fourth pin of the common mode inductor is connected to the anode end of the second diode; The first pin of the common-mode inductor and the second pin of the common-mode inductor are directly connected in the common-mode inductor, and the third pin of the common-mode inductor and the fourth pin of the common-mode inductor are directly connected in the common-mode inductor.

8. The differential bus transceiver system according to claim 6, characterized in that: The differential bus transceiver system further includes a high-frequency interference elimination circuit, wherein the high-frequency interference elimination circuit includes a first terminal resistor, a second terminal resistor and a filter capacitor; The first end of the first terminal resistor is connected to the high-level interaction end of the differential bus transceiver, the first end of the second terminal resistor is connected to the low-level interaction end of the differential bus transceiver, the second end of the first terminal resistor and the second end of the second terminal resistor are connected to the first end of the filter capacitor, and the second end of the filter capacitor is connected to the ground end of the differential bus transceiver.

9. The differential bus transceiver system according to claim 8, characterized in that: The differential bus transceiver system is arranged in a metal housing, and the ground terminal of the differential bus transceiver, the anode terminal of the fifth diode and the cathode terminal of the sixth diode are connected and then grounded; The discharge end of the gas discharge tube is connected to the housing ground of the metal shell so that the discharge end of the gas discharge tube is grounded.

10. The differential bus transceiver system according to claim 8, characterized in that: The differential bus transceiver is an RS485 transceiver or a controller area network transceiver.

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