An aviation airborne equipment arinc664 interface lightning protection circuit and a working method thereof

Abstract

The application belongs to the technical field of lightning protection of aviation airborne equipment interface, and discloses an aviation airborne equipment ARINC664 interface lightning protection circuit and a working method thereof. A first-stage energy discharge circuit, an electromagnetic energy coupling discharge circuit, a secondary energy discharge circuit and a residual energy transient closing circuit are sequentially arranged between a signal line of the ARINC664 interface and a subsequent-stage regulating circuit to form a hierarchical and path-divided lightning surge protection structure. The first-stage energy discharge circuit can directly discharge part of lightning surge energy entering the interface signal line to the case ground, thereby reducing the energy impact borne by the subsequent circuit. The primary inductor coil and the secondary inductor coil are coupled through a magnetic core to realize signal transmission, electromagnetically isolate the residual surge energy and couple the residual surge energy to be transmitted, thereby reducing the direct transmission of the surge voltage and common-mode interference to the subsequent-stage regulating circuit.

Description

Technical Field

[0001] This invention belongs to the field of lightning protection technology for airborne equipment interfaces, specifically relating to a lightning protection circuit for the ARINC664 interface of airborne equipment and its working method. Background Technology

[0002] The signal interfaces of airborne electronic equipment (AFEE) are crucial channels for data exchange between aircraft electronic systems and external devices. Their lightning protection performance directly affects the safety and reliability of AFEE system operation. Aircraft may be struck by lightning during flight. Although the transient high current and voltage generated by lightning strikes are primarily conducted along the fuselage skin, they still create strong transient electromagnetic fields in the fuselage structure and surrounding space. These fields can intrude into the interface circuits of AFEE through capacitive coupling, inductive coupling, or cable conduction, leading to communication anomalies, damage to interface devices, or equipment malfunctions. Therefore, AFEE typically requires lightning transient sensitivity testing according to Chapter 22 of DO-160G, and the appropriate protection level is determined based on the equipment's installation location and its electromagnetic environment. Higher protection levels are suitable for equipment and its interconnecting cables installed in harsh electromagnetic environments such as near engines.

[0003] In existing airborne equipment, signal interfaces such as RS-232, RS-422, RS-485, ARINC429, CAN, discrete signal interfaces, and analog signal interfaces typically have low operating voltages, low transmission currents, and are highly sensitive to transient overvoltages and overcurrents. Therefore, appropriate surge protection circuits need to be incorporated into the interface circuitry. For low-speed communication interfaces, transient voltage suppressors, gas discharge tubes, current-limiting resistors, or electrostatic discharge protection diodes can typically be used to form one or more levels of protection to discharge and clamp lightning surge energy.

[0004] The ARINC664 interface, a high-speed communication interface used in avionics, can achieve communication rates of 100Mbps or 1Gbps, placing high demands on impedance continuity, parasitic capacitance, and signal integrity of the transmission path. Lightning protection devices and their connecting branches in the communication loop can create additional parasitic capacitance and impedance abrupt changes. When the parasitic capacitance is large or there are physical forks in the signal path, it can easily cause high-speed signal waveform distortion, enhanced reflection, and degraded communication quality. Therefore, lightning protection structures suitable for ordinary low-speed signal interfaces are difficult to directly apply to the ARINC664 high-speed communication interface.

[0005] In existing technologies, one approach uses multiple transient suppression devices connected in series or parallel to reduce the ground capacitance of a single device on the communication line and to provide graded clamping of surge voltage. However, when multiple sets of diodes or transient suppression devices are connected to the communication line, they can easily create branches and impedance discontinuities on high-speed signal lines, affecting the signal integrity of the ARINC664 interface. Furthermore, this type of parallel protection structure places high demands on the turn-on voltage, response time, and device consistency of each protection device. When some devices turn on prematurely or fail, the remaining devices may not be able to effectively withstand subsequent surge energy, leading to a decrease in overall lightning protection reliability.

[0006] Another existing solution uses a multi-stage discharge tube and diode to form a lightning and electrostatic discharge (ESD) protection device. The discharge tubes dissipate large surge energy, and the diodes clamp residual voltage. However, this type of circuit typically requires multiple protective devices between the signal line and ground, which can easily increase the parasitic capacitance to ground of the communication line. It is more suitable for low-speed communication interfaces and cannot meet the low parasitic capacitance requirements of the ARINC664 high-speed communication interface. Furthermore, the existing solution has a limited capacity to withstand lightning surge energy, making it difficult to meet the high-level lightning transient protection requirements of DO-160G for airborne equipment installed in harsh electromagnetic environments.

[0007] Therefore, existing lightning protection technology for the ARINC664 interface of airborne equipment is insufficient to simultaneously address high-level lightning surge energy dissipation, residual voltage suppression, protection of sensitive downstream chips, and the integrity of high-speed communication signals. There is an urgent need for an ARINC664 interface lightning protection circuit for airborne equipment with small parasitic capacitance, strong energy dissipation capability, and adaptability to different downstream circuit withstand voltage requirements, as well as its operating method. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems of insufficient lightning protection energy level, large parasitic capacitance, and difficulty in ensuring the integrity of high-speed communication signals and protecting sensitive downstream chips in existing ARINC664 interface surge protection circuits, and to provide a surge protection circuit for ARINC664 interface of airborne equipment and its working method.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a surge protection circuit for the ARINC664 interface of an airborne equipment, including a primary energy discharge circuit, an electromagnetic energy coupling discharge circuit, a secondary energy discharge circuit, and a residual energy transient shutdown circuit. The primary energy discharge circuit is connected between the signal line of the ARINC664 interface and the chassis ground. The electromagnetic energy coupling discharge circuit is located between the first-stage energy discharge circuit and the subsequent conditioning circuit. The electromagnetic energy coupling discharge circuit includes a primary induction coil and a secondary induction coil. The primary induction coil and the secondary induction coil are coupled through a magnetic core. The primary induction coil is connected to the signal input side of the ARINC664 interface, and the secondary induction coil is connected to the subsequent conditioning circuit. The secondary energy discharge circuit is connected between the secondary induction coil and ground; The residual energy transient shutdown circuit is connected in series between the secondary induction coil and the subsequent conditioning circuit.

[0010] A further improvement of the present invention is that the primary energy discharge circuit includes a gas discharge tube and a resistor-capacitor (RC) discharge circuit. The gas discharge tube and the RC discharge circuit are connected in parallel. One end of both the gas discharge tube and the RC discharge circuit is connected to the signal line of the ARINC664 interface, and the other end is connected to the chassis ground.

[0011] A further improvement of the present invention is that the electromagnetic energy coupling discharge circuit adopts a network transformer, the primary coil of the network transformer constitutes a primary induction coil, and the secondary coil of the network transformer constitutes a secondary induction coil.

[0012] A further improvement of the present invention is that the number of turns of the primary induction coil is The number of turns of the secondary induction coil is The turns ratio of the primary induction coil to the secondary induction coil is And satisfy: ; in, The back electromotive force generated by the primary induction coil. This is the induced voltage across the secondary induction coil.

[0013] A further improvement of the present invention is that the secondary energy discharge circuit includes a transient voltage suppressor or a gas discharge tube, one end of which is connected to the output terminal of the secondary induction coil and the other end is grounded; The residual energy transient shutdown circuit includes a surge suppression resistor or a transient blocking unit, which is connected in series between the output terminal of the secondary induction coil and the subsequent conditioning circuit. The connection node between the secondary energy discharge circuit and the secondary induction coil is located on the input side of the residual energy transient shutdown circuit.

[0014] Secondly, the present invention provides a method for operating a surge protection circuit for an ARINC664 interface of an airborne device, comprising the following steps: After a lightning surge enters the signal line of the ARINC664 interface, a portion of the energy in the lightning surge is discharged to the chassis ground through a primary energy discharge circuit. The remaining lightning surge current flows through the primary induction coil, causing the primary induction coil to generate a reverse electromotive force that is opposite to the direction of the lightning surge current change. Through the magnetic core, part of the energy in the lightning surge is coupled and transferred to the secondary induction coil. The induced voltage across the secondary induction coil is controlled by the turns ratio of the primary induction coil to the secondary induction coil. The surge energy of lightning coupled to the secondary induction coil is discharged or suppressed through the secondary energy discharge circuit; The residual surge current flowing to the subsequent conditioning circuit is limited or cut off by the residual energy transient shutdown circuit.

[0015] A further improvement of the present invention is that when the lightning surge voltage on the signal line of the ARINC664 interface exceeds the breakdown threshold of the gas discharge tube, the gas discharge tube is turned on and the lightning surge energy is discharged to the chassis ground; before the gas discharge tube is turned on, the peak energy generated by the lightning surge is absorbed by the RC discharge circuit.

[0016] A further improvement of the present invention is that the breakdown threshold of the gas discharge tube is 75V, and the time from the lightning surge voltage reaching the breakdown threshold to the conduction of the gas discharge tube is 20μs.

[0017] A further improvement of this invention is that when a lightning surge current flows through the primary induction coil, the back electromotive force generated by the primary induction coil... satisfy: ; in, This is the equivalent inductance of the primary induction coil. The rate of change of the lightning surge current flowing through the primary induction coil; When lightning surge energy causes the magnetic core to saturate briefly, the equivalent inductance of the primary induction coil decreases to limit the back electromotive force, and some of the lightning surge energy is absorbed through the eddy current loss and hysteresis loss of the magnetic core.

[0018] A further improvement of this invention is that the target induced voltage across the secondary induction coil is determined based on the allowable input voltage of the protected chip in the subsequent conditioning circuit. Based on the back electromotive force generated by the primary induction coil Target induced voltage The ratio determines the number of turns ratio According to the stated turns ratio Set the number of turns of the primary induction coil and the number of turns of the secondary induction coil .

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention forms a hierarchical, multi-path lightning surge protection structure by sequentially configuring a primary energy discharge circuit, an electromagnetic energy coupling discharge circuit, a secondary energy discharge circuit, and a residual energy transient shutdown circuit between the signal lines of the ARINC664 interface and the subsequent conditioning circuit. The primary energy discharge circuit directly discharges a portion of the lightning surge energy entering the interface signal lines to the chassis ground, reducing the energy impact on subsequent circuits. The primary and secondary induction coils are coupled via magnetic cores, achieving signal transmission while electromagnetically isolating and coupling the remaining surge energy, reducing the direct transmission of surge voltage and common-mode interference to the subsequent conditioning circuit. The secondary energy discharge circuit further discharges the surge energy on the output side of the secondary induction coil, further suppressing the residual voltage. The series-connected residual energy transient shutdown circuit limits or cuts off the residual surge current flowing to the subsequent conditioning circuit, thereby improving the protection reliability of the sensitive chips in the subsequent stage. The various protection circuits work together to ensure that lightning surge energy is attenuated step by step in the order of primary discharge, magnetic coupling transmission, secondary discharge, and residual current suppression. This avoids a single protection device bearing all the lightning energy and, while improving the lightning protection capability of the ARINC664 interface, reduces the impact of the lightning protection structure on the transmission quality of high-speed communication signals. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a three-level lightning protection structure; Figure 2 This is a schematic diagram of an electromagnetic energy coupling and discharge circuit. Figure 3 A schematic diagram of the surge protection circuit structure for the ARINC664 communication interface; Figure 4 Waveform diagram of a 750V / 750A positive polarity injection test onto the ARINC664TX+ pins; Figure 5 Waveform diagram of a 750V / 750A negative polarity injection test into the ARINC664TX+ pin; Figure 6 Waveform diagram of 750V / 750A positive polarity injection test for ARINC664TX pins; Figure 7 Waveform diagram of 750V / 750A negative polarity injection test for ARINC664TX pins. Detailed Implementation

[0021] To further understand the content of this invention, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the invention.

[0022] Example 1: The surge protection circuit for the ARINC664 interface of the airborne equipment in this embodiment includes a primary energy discharge circuit, an electromagnetic energy coupling discharge circuit, a secondary energy discharge circuit, and a residual energy transient shutdown circuit.

[0023] The primary energy discharge circuit is connected between the signal line of the ARINC664 interface and the chassis ground. The electromagnetic energy coupling discharge circuit is located between the primary energy discharge circuit and the subsequent conditioning circuit. The secondary energy discharge circuit is connected between the secondary induction coil of the electromagnetic energy coupling discharge circuit and ground. The residual energy transient shutdown circuit is connected in series between the secondary induction coil and the subsequent conditioning circuit.

[0024] See Figure 1 From the perspective of overall lightning protection function, the multi-level lightning protection design adopted in this embodiment can be divided into first-level lightning protection, second-level lightning protection and third-level lightning protection.

[0025] Primary lightning protection is used to discharge most of the energy in lightning surges, and can employ gas discharge tubes and low-capacitance transient voltage suppressor arrays. The gas discharge tubes are responsible for discharging the main lightning energy, the low-capacitance transient voltage suppressor arrays are used to further clamp the residual surge voltage, and the RC filter circuit is used to absorb transient spikes formed before the gas discharge tubes are turned on or after the primary energy discharge.

[0026] Secondary surge protection is used to reduce the residual surge voltage and surge current after primary surge protection. It can use current-limiting resistors, surge suppression resistors or transient blocking units to reduce the residual voltage to a range that the subsequent conditioning circuit can withstand, such as reducing the residual voltage to below 30V.

[0027] Level 3 surge protection is used to further protect sensitive chips in the subsequent conditioning circuit. Depending on the specific type of the protected circuit, it can employ electrostatic discharge diodes or isolation DC / DC devices. In this embodiment, the electromagnetic energy coupling discharge circuit, through magnetic isolation, energy coupling transfer, and turns ratio control, can effectively achieve a combination of some functions of traditional level 2 and level 3 surge protection.

[0028] In this embodiment, the primary energy discharge circuit includes a gas discharge tube and a resistor-capacitor (RC) discharge circuit. The gas discharge tube and the RC discharge circuit are connected in parallel. One end of both the gas discharge tube and the RC discharge circuit is connected to the signal line of the ARINC664 interface, and the other end is connected to the chassis ground.

[0029] The gas discharge tube is used to discharge most of the lightning surge energy on the ARINC664 interface signal lines to the chassis ground. The RC bleeder circuit is used to absorb the transient spike energy generated by the lightning surge before the gas discharge tube is turned on. The RC bleeder circuit can be constructed using a 1kΩ resistor and a 100pF capacitor. In actual implementation, the internal connection form of the RC bleeder circuit can be determined according to the impedance requirements, frequency characteristics, and lightning surge absorption requirements of the ARINC664 interface.

[0030] The breakdown threshold of the gas discharge tube can be set to 75V. When the lightning surge voltage on the ARINC664 interface signal line is lower than 75V, the gas discharge tube is in a non-conductive state; when the lightning surge voltage reaches or exceeds 75V, the gas discharge tube breaks down and conducts, discharging the lightning surge energy from the ARINC664 interface signal line to the chassis ground.

[0031] The gas discharge tube has a response time of approximately 20 μs from the lightning surge voltage reaching the breakdown threshold to the gas discharge tube turning on. Before the gas discharge tube turns on, the transient spike energy generated by the lightning surge is absorbed by the RC bleeder circuit; after the gas discharge tube turns on, it undertakes the main discharge of lightning surge energy, thereby reducing the lightning energy entering the subsequent electromagnetic energy coupling bleeder circuit.

[0032] In one optional implementation, the primary energy discharge circuit can also be configured with a low-capacitance transient voltage suppressor array. The gas discharge tube handles the main energy discharge, and the low-capacitance transient voltage suppressor array clamps the residual surge peak after the gas discharge tube discharges. The RC discharge circuit absorbs the remaining transient spikes. The specific connection locations and number of components in the low-capacitance transient voltage suppressor array can be determined based on the parasitic capacitance limitations and surge protection requirements of the ARINC664 interface.

[0033] See Figure 2 The electromagnetic energy coupling and discharge circuit includes a primary induction coil, a secondary induction coil, and a magnetic core. The primary and secondary induction coils are electromagnetically coupled through the magnetic core. The primary induction coil is connected to the signal input side of the ARINC664 interface, and the secondary induction coil is connected to the subsequent conditioning circuit.

[0034] The primary induction coil is used to receive the remaining lightning surge energy after it has been processed by the first-stage energy discharge circuit. When the lightning surge current flows through the primary induction coil, the current in the primary induction coil changes rapidly, an alternating magnetic flux is formed in the magnetic core, and a reverse electromotive force is generated by the primary induction coil in the opposite direction to the change of the surge current.

[0035] The secondary induction coil receives the electromagnetic energy transmitted by the primary induction coil through magnetic core coupling and forms an induced voltage across its terminals. By controlling the turns ratio of the primary and secondary induction coils, the induced voltage across the secondary induction coil can be controlled, ensuring that the voltage entering the subsequent conditioning circuit is within the range that the protected chip can withstand.

[0036] See Figure 3 In this embodiment, the electromagnetic energy coupling discharge circuit can employ a network transformer. The primary coil of the network transformer constitutes a primary induction coil, and the secondary coil constitutes a secondary induction coil. The network transformer can provide magnetic isolation protection against lightning surge energy while achieving high-speed communication signal isolation and efficient transmission for ARINC664.

[0037] Network transformers provide electrical isolation between the primary and secondary circuits, blocking the direct transmission of DC components and common-mode surges to subsequent conditioning circuits. The design withstand voltage of a network transformer can be set to 2kV–3kV to withstand instantaneous high voltages caused by lightning strikes.

[0038] When a lightning surge current instantaneously flows through the primary induction coil of a network transformer, the inductance of the primary induction coil generates a back electromotive force (EMF) due to the sudden change in current. According to Lenz's law, the direction of the generated back EMF is opposite to the direction of the lightning surge current. satisfy: ; in, This is the equivalent inductance of the primary induction coil. The rate of change of lightning surge current flowing through the primary induction coil.

[0039] The alternating magnetic flux generated by the primary induction coil is transmitted to the secondary induction coil through the magnetic core, causing the secondary induction coil to generate an induced voltage and transferring part of the energy in the lightning surge from the primary side to the secondary side.

[0040] When the lightning surge energy entering the primary induction coil is high, the high-energy current impact can cause the magnetic core to saturate briefly. After the magnetic core saturates briefly, the equivalent inductance of the primary induction coil decreases sharply, thereby limiting the back electromotive force generated by the primary induction coil. At the same time, the eddy current loss and hysteresis loss in the magnetic core material can absorb some of the lightning surge energy and convert the absorbed electromagnetic energy into heat.

[0041] Let the number of turns of the primary induction coil be... The number of turns of the secondary induction coil is The turns ratio of the primary induction coil to the secondary induction coil is The back electromotive force generated by the primary induction coil is The induced voltage across the secondary induction coil is Then the following condition is met: .

[0042] in, This represents the ratio between the back electromotive force of the primary induction coil and the induced voltage of the secondary induction coil. This indicates the turns ratio of the primary induction coil to the secondary induction coil. This indicates the turns ratio of the network transformer.

[0043] When designing an electromagnetic energy coupling discharge circuit, the target induced voltage across the secondary induction coil is first determined based on the allowable input voltage of the protected chip in the subsequent conditioning circuit. Then, based on the possible back electromotive force generated by the primary induction coil... Target induced voltage The ratio between them determines the turns ratio. Finally, according to the determined turns ratio Set the number of turns of the primary induction coil and the number of turns of the secondary induction coil .

[0044] By adjusting the turns ratio of the primary and secondary induction coils, the residual surge voltage across the secondary induction coil can be controlled within the allowable range of the sensitive chip in the subsequent conditioning circuit. Since different communication chips, conditioning chips, and interface chips have different allowable input voltages, this embodiment can match protected chips with different withstand voltage values ​​by adjusting the turns ratio.

[0045] Electromagnetic energy coupling discharge circuits can be applied not only to ARINC664 interfaces, but also to other communication circuits or conditioning interface circuits to achieve magnetic isolation, coupling transfer, and secondary voltage control of lightning surge energy.

[0046] The secondary energy discharge circuit is connected between the secondary induction coil and ground. The secondary energy discharge circuit includes a transient voltage suppressor or a gas discharge tube. One end of the transient voltage suppressor or gas discharge tube is connected to the output terminal of the secondary induction coil, and the other end is grounded, thus forming a secondary energy discharge branch between the output terminal of the secondary induction coil and ground.

[0047] When the primary induction coil transfers some of the lightning surge energy to the secondary induction coil through magnetic core coupling, an induced voltage is generated across the secondary induction coil. A transient voltage suppressor or gas discharge tube clamps the induced voltage output by the secondary induction coil and discharges the corresponding lightning surge energy to ground to prevent excessively high induced voltage from directly entering the subsequent conditioning circuit.

[0048] A residual energy transient shutdown circuit is connected in series between the secondary induction coil and the subsequent conditioning circuit. This circuit includes a surge suppression resistor or a transient latch-up unit. The surge suppression resistor or transient latch-up unit is connected in series between the output of the secondary induction coil and the subsequent conditioning circuit.

[0049] The connection point between the secondary energy discharge circuit and the secondary induction coil is located on the input side of the residual energy transient shutdown circuit. Therefore, the lightning surge energy output by the secondary induction coil is first discharged or suppressed by the secondary energy discharge circuit, and the residual surge energy that is not completely discharged by the secondary energy discharge circuit then enters the residual energy transient shutdown circuit.

[0050] When the residual energy transient shutdown circuit uses a surge suppression resistor, the residual surge current flowing to the subsequent conditioning circuit is limited by the surge suppression resistor, so as to reduce the impact of residual current on the sensitive chips in the subsequent stage.

[0051] When the residual energy transient shutdown circuit employs a transient blocking unit, the transient blocking unit prevents transient interference from continuing to propagate to subsequent conditioning circuits by interrupting the current. This operating mode differs from the traditional grounding surge shunt method, as it primarily suppresses residual surges through a current interruption mechanism.

[0052] Under normal communication conditions, the transient latching unit is in a low-impedance conduction state, having minimal impact on the ARINC664 communication signal. When the residual surge current exceeds the operating condition of the transient latching unit, it switches to a high-impedance state, limiting or cutting off the residual surge current flowing to the subsequent conditioning circuit. The transient latching unit has a bandwidth of up to 3GHz and can be used for protection of ARINC664 high-speed communication signals.

[0053] When the surge protection circuit described in this embodiment is working, the lightning surge first enters the signal line of the ARINC664 interface. Before the lightning surge voltage reaches the breakdown threshold of the gas discharge tube, the RC bleeder circuit absorbs the transient spike energy generated by the lightning surge.

[0054] When the lightning surge voltage reaches or exceeds the breakdown threshold of 75V of the gas discharge tube, the gas discharge tube conducts, discharging most of the energy in the lightning surge to the chassis ground. Transient spike energy that has not yet been dissipated during the approximately 20μs conduction process of the gas discharge tube is absorbed by the RC bleeder circuit.

[0055] The remaining lightning surge current, after being processed by the primary energy discharge circuit, flows through the primary induction coil, causing the primary induction coil to generate a reverse electromotive force that is opposite to the direction of the lightning surge current change. Through the magnetic core, part of the energy in the lightning surge is coupled and transferred to the secondary induction coil.

[0056] Based on the turns ratio of the primary and secondary induction coils, the induced voltage across the secondary induction coil is controlled so that the surge voltage output from the secondary side matches the withstand voltage of the protected chip in the subsequent conditioning circuit.

[0057] After the secondary induction coil generates an induced voltage, a transient voltage suppressor or gas discharge tube connected between the output terminal of the secondary induction coil and ground clamps the induced voltage and discharges the lightning surge energy coupled to the secondary side to ground.

[0058] Residual surge energy that is not completely discharged by the secondary energy discharge circuit enters a surge suppression resistor or transient blocking unit connected in series. The surge suppression resistor limits the residual surge current flowing to the subsequent conditioning circuit, or the transient blocking unit prevents the residual surge from continuing to propagate to the subsequent conditioning circuit through a current cutoff mechanism.

[0059] Through the above process, lightning surge energy undergoes primary energy release, electromagnetic energy coupling and transfer, secondary energy release, and residual energy transient shutdown in sequence, achieving the stepwise release and gradual attenuation of lightning surge energy.

[0060] In the corresponding three-level surge protection diagram, the first-level surge protection is used to discharge the main energy of lightning surges, the second-level surge protection is used to reduce the residual voltage and residual current after the first-level surge protection, and the third-level surge protection is used to protect the sensitive chips in the subsequent conditioning circuit. This diagram reflects the process of lightning surge energy attenuating step by step from the interface input side to the subsequent conditioning circuit.

[0061] In the corresponding electromagnetic energy coupling and discharge design diagram, the primary induction coil, secondary induction coil, and magnetic core constitute a magnetic coupling structure, and the output terminal of the secondary induction coil is connected to the secondary energy discharge circuit. Part of the energy in the lightning surge is transferred from the primary induction coil to the secondary induction coil through the magnetic core, and then the secondary energy discharge circuit forms a corresponding discharge loop.

[0062] In the corresponding ARINC664 communication interface surge protection circuit diagram, the primary gas discharge tube surge protection circuit is set between the ARINC664 signal line and the chassis ground, the network transformer is set between the primary energy discharge circuit and the subsequent conditioning circuit, the secondary energy discharge circuit is set between the secondary side of the network transformer and ground, and the residual energy transient shutdown circuit is set in series between the secondary side of the network transformer and the subsequent conditioning circuit.

[0063] The surge protection circuit for the ARINC664 interface of airborne equipment described in this embodiment has been applied to the airborne electronic equipment of a certain type of civil aircraft engine. For the ARINC664 communication interface of this airborne electronic equipment, the surge protection circuit consists of a primary gas discharge tube surge protection circuit, an electromagnetic energy coupling discharge circuit, and a residual energy transient shutdown circuit, wherein the electromagnetic energy coupling discharge circuit uses a network transformer.

[0064] In this specific application, the gas discharge tube is connected to the ARINC664 signal line and the chassis ground. When the lightning surge voltage exceeds the 75V breakdown threshold of the gas discharge tube, the gas discharge tube conducts and directly discharges the lightning surge energy to the chassis ground. The lightning surge peak energy before the gas discharge tube conducts is absorbed by the RC bleeder circuit.

[0065] The remaining lightning surge current enters the primary coil of the network transformer. Due to the rapid change in the lightning surge current, the internal inductance of the network transformer generates a back electromotive force, and based on the principle of magnetic energy transfer, transfers part of the lightning surge energy from the primary side to the secondary side of the network transformer.

[0066] The protection circuit on the secondary side of the network transformer discharges or suppresses lightning surge energy transmitted to the secondary side. The output voltage on the secondary side is controlled by adjusting the turns ratio of the primary and secondary coils of the network transformer. When the residual energy transient shutdown circuit uses a transient blocking unit, it protects the downstream conditioning circuit by cutting off the residual surge current.

[0067] Example 2: To verify the lightning protection circuit and its working method of this embodiment, a lightning strike test was conducted on the airborne electronic equipment of a certain type of civil aircraft engine that uses the lightning protection circuit of this embodiment in the lightning strike test laboratory of a certain company, in accordance with the test procedures specified in the DO-160G standard.

[0068] The ARINC664 interface pin injection test conditions for this device include: Waveform level 3 / 3, open circuit voltage 1500V, short-circuit current The current rating is 60A, and the test frequency is 1MHz. Waveform rating 5A / 5A, open circuit voltage 750V, short-circuit current It is 750A.

[0069] During the experiment, 750V / 750A lightning surge injection tests were conducted on the ARINC664TX+ and ARINC664TX- pins with positive and negative polarities, respectively.

[0070] See Figure 4 and Figure 5 The corresponding ARINC664TX+ pin injection test waveform records the test waveforms when a 750V / 750A positive and negative polarity lightning surge is applied to the ARINC664TX+ pin.

[0071] See Figure 6 and Figure 7The corresponding ARINC664TX-pin injection test waveform records the test waveforms when a 750V / 750A positive and negative polarity lightning surge is applied to the ARINC664TX-pin.

[0072] The above-mentioned test input conditions and test waveforms are used to verify the lightning energy discharge capability of the lightning protection circuit described in this embodiment under DO-160G high-level lightning transient conditions.

[0073] This embodiment discharges the main energy in lightning surges through a primary energy discharge circuit, achieves electrical isolation between the primary and secondary sides, lightning energy coupling and transfer, and secondary induced voltage control through an electromagnetic energy coupling discharge circuit, discharges or suppresses lightning surge energy coupled to the secondary side through a secondary energy discharge circuit, and limits or cuts off the residual surge current flowing to the subsequent conditioning circuit through a residual energy transient shutdown circuit.

[0074] This invention can reduce the number of high parasitic capacitance surge protection devices directly connected to ground in the ARINC664 high-speed signal circuit, reduce the impact of surge protection circuit on the impedance continuity of the communication signal transmission path, and achieve higher-level protection against lightning surge energy while ensuring the quality of ARINC664 high-speed communication signals.

[0075] By adjusting the turns ratio of the primary and secondary induction coils, protected chips with different withstand voltage values ​​can be matched, making this embodiment applicable to different communication circuits and conditioning interface circuits. The lightning protection circuit and its operating method described in this embodiment can be used to achieve Level 5 lightning energy protection as specified in DO-160G, and are suitable for airborne electronic equipment installed in harsh electromagnetic environments such as engines.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A surge protection circuit for the ARINC664 interface of an aircraft airborne equipment, characterized in that, It includes a primary energy discharge circuit, an electromagnetic energy coupling discharge circuit, a secondary energy discharge circuit, and a residual energy transient shutdown circuit; The primary energy discharge circuit is connected between the signal line of the ARINC664 interface and the chassis ground; The electromagnetic energy coupling discharge circuit is located between the first-stage energy discharge circuit and the subsequent conditioning circuit. The electromagnetic energy coupling discharge circuit includes a primary induction coil and a secondary induction coil. The primary induction coil and the secondary induction coil are coupled through a magnetic core. The primary induction coil is connected to the signal input side of the ARINC664 interface, and the secondary induction coil is connected to the subsequent conditioning circuit. The secondary energy discharge circuit is connected between the secondary induction coil and ground; The residual energy transient shutdown circuit is connected in series between the secondary induction coil and the subsequent conditioning circuit.

2. The surge protection circuit for the ARINC664 interface of airborne equipment according to claim 1, characterized in that, The primary energy discharge circuit includes a gas discharge tube and a resistor-capacitor (RC) discharge circuit. The gas discharge tube and the RC discharge circuit are connected in parallel. One end of both the gas discharge tube and the RC discharge circuit is connected to the signal line of the ARINC664 interface, and the other end is connected to the chassis ground.

3. The surge protection circuit for the ARINC664 interface of airborne equipment according to claim 1, characterized in that, The electromagnetic energy coupling discharge circuit uses a network transformer. The primary coil of the network transformer forms the primary induction coil, and the secondary coil of the network transformer forms the secondary induction coil.

4. The surge protection circuit for the ARINC664 interface of airborne equipment according to claim 1, characterized in that, The number of turns of the primary induction coil is The number of turns of the secondary induction coil is The turns ratio of the primary induction coil to the secondary induction coil is And satisfy: ； in, The back electromotive force generated by the primary induction coil. This is the induced voltage across the secondary induction coil.

5. A surge protection circuit for an ARINC664 interface of an airborne equipment according to claim 1, characterized in that, The secondary energy discharge circuit includes a transient voltage suppressor or a gas discharge tube. One end of the transient voltage suppressor or gas discharge tube is connected to the output terminal of the secondary induction coil, and the other end is grounded. The residual energy transient shutdown circuit includes a surge suppression resistor or a transient blocking unit, which is connected in series between the output terminal of the secondary induction coil and the subsequent conditioning circuit. The connection node between the secondary energy discharge circuit and the secondary induction coil is located on the input side of the residual energy transient shutdown circuit.

6. A method for operating the surge protection circuit for the ARINC664 interface of an airborne equipment as described in any one of claims 1 to 5, characterized in that, Includes the following steps: After a lightning surge enters the signal line of the ARINC664 interface, a portion of the energy in the lightning surge is discharged to the chassis ground through a primary energy discharge circuit. The remaining lightning surge current flows through the primary induction coil, causing the primary induction coil to generate a reverse electromotive force that is opposite to the direction of the lightning surge current change. Through the magnetic core, part of the energy in the lightning surge is coupled and transferred to the secondary induction coil. The induced voltage across the secondary induction coil is controlled by the turns ratio of the primary induction coil to the secondary induction coil. The surge energy of lightning coupled to the secondary induction coil is discharged or suppressed through the secondary energy discharge circuit; The residual surge current flowing to the subsequent conditioning circuit is limited or cut off by the residual energy transient shutdown circuit.

7. The operating method of the ARINC664 interface surge protection circuit for airborne equipment according to claim 6, characterized in that, When the surge voltage on the signal line of the ARINC664 interface exceeds the breakdown threshold of the gas discharge tube, the gas discharge tube turns on and discharges the surge energy to the chassis ground; before the gas discharge tube turns on, the spike energy generated by the surge is absorbed by the RC discharge circuit.

8. The operating method of the ARINC664 interface surge protection circuit for airborne equipment according to claim 7, characterized in that, The breakdown threshold of the gas discharge tube is 75V, and the time from the lightning surge voltage reaching the breakdown threshold to the conduction time is 20μs.

9. The operating method of the ARINC664 interface surge protection circuit for airborne equipment according to claim 6, characterized in that, When a lightning surge current flows through the primary induction coil, the primary induction coil generates a back electromotive force. satisfy: ； in, This is the equivalent inductance of the primary induction coil. The rate of change of the lightning surge current flowing through the primary induction coil; When lightning surge energy causes the magnetic core to saturate briefly, the equivalent inductance of the primary induction coil decreases to limit the back electromotive force, and some of the lightning surge energy is absorbed through the eddy current loss and hysteresis loss of the magnetic core.

10. The operating method of the ARINC664 interface surge protection circuit for airborne equipment according to claim 6, characterized in that, The target induced voltage across the secondary induction coil is determined based on the allowable input voltage of the protected chip in the subsequent conditioning circuit. Based on the back electromotive force generated by the primary induction coil Target induced voltage The ratio determines the number of turns ratio According to the stated turns ratio Set the number of turns of the primary induction coil and the number of turns of the secondary induction coil .

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