US-12627136-B2 - Electrical device with indirect lightning protection, attitude and heading reference system, and aircraft

US12627136B2US 12627136 B2US12627136 B2US 12627136B2US-12627136-B2

Abstract

An electrical device is disclosed, with indirect lightning protection, having an electrically conductive housing for housing electrical components. The electrical device has an electrical data interface connected to the electrical components in order to transmit electrical signals from the components out of the housing, or in order to transmit external electrical signals into the housing in the components. An electrical power supply interface is provided, which supplies the electronic components with electrical power from an external power source. The electrical data interface and the electrical power supply interface are constructed in such a way that the electrical components are galvanically isolated from the housing and the input/output lines of the data interface and the power supply interface, such that damage to the components by a current pulse brought about by lightning is prevented. An attitude and heading reference system and an aircraft comprising the electrical device are further provided.

Inventors

Peter Zeller

Assignees

NORTHROP GRUMMAN LITEF GMBH

Dates

Publication Date: 20260512
Application Date: 20220915
Priority Date: 20211020

Claims (12)

1 . An electrical device with indirect lightning protection, comprising: an electrically conductive housing, within which electrical components are accommodated, wherein the electrical components are adapted to provide attitude and heading reference data for air navigation, an electrical data interface, which is connected to the electrical components in order to transmit internal electrical signals from the components out of the housing, or to transmit external electrical signals into the housing to the components, an electrical power supply interface, which supplies electrical power to the electrical components from an external power source, wherein the electrical data interface and the electrical power supply interface are configured in such a manner that the electrical components are galvanically isolated from the housing and from the input/output lines of the data interface and the power supply interface, so that damage to the components by a lightning-induced current pulse is prevented, and wherein the electrical data interface has an external data interface part that is connectable to a peripheral electrical conductor structure and an internal data interface part that is connected to the components, which are galvanically isolated, wherein data transmission between the external and the internal data interface parts is done optically, and wherein the electrical data interface includes potential equalization elements which are interconnected between two-core differential signal input/output lines in order to raise the input/output lines to the same electrical potential in the event of a lightning-induced voltage pulse to prevent a voltage flashover between the lines.
2 . The electrical device according to claim 1 , wherein the electrical components comprise a fiber gyrocompass or a MEMS gyro and electrical circuits for controlling the compass, as well as for evaluating and transmitting the attitude and heading data.
3 . The electrical device according to claim 1 , wherein the electrical data interface is adapted to read and output data digitally, in particular, in the ARINC 429 protocol, in the RS-422 protocol, in the RS-485 protocol, in the CAN protocol, in the ETHERNET protocol, or in the DISCRETE protocol.
4 . The electrical device according to claim 1 , wherein the electrical data interface is adapted to output attitude and heading reference data analogously.
5 . The electrical device according to claim 1 , wherein the electrical components are provided with lightning protection of a threat level greater than or equal to 3 in accordance with DIN EN 62305.
6 . The electrical device according to claim 1 , wherein the electrical power supply interface has an external power supply interface part that is connectable to an external power source and an internal power supply interface part that is connected to the components, which are galvanically isolated, wherein electrical power transmission between the external and the internal power supply interface parts is done by magnetic induction or by transmission of electromagnetic waves.
7 . The electrical device according to claim 1 , wherein the electrical components are protected from a lightning-induced voltage pulse by ESD protection diodes.
8 . The electrical device according to claim 1 , wherein the potential equalization elements comprise suppressor diodes, varistors, or series resistor elements.
9 . The electrical device according to claim 1 , wherein the input/output lines of the electrical data interface and the power supply interface are arranged spaced apart from one another in such a manner that a voltage flashover between the lines is prevented in the event of a lightning-induced voltage pulse.
10 . The electrical device according to claim 1 , wherein a minimum distance between the input/output lines of the electrical data interface and the power supply interface is greater than 2 mm, greater than 2.5 mm, or greater than 3 mm.
11 . An attitude and heading reference system for air navigation, comprising an electrical device according to claim 1 .
12 . An aircraft comprising an electrical device according to claim 1 .

Description

This application is a U.S. National Stage Application filed under 35 U.S.C. § 371 of PCT/EP2022/075711, filed Sep. 15, 2022, and entitled “ELECTRICAL DEVICE WITH INDIRECT LIGHTNING PROTECTION, ATTITUDE AND HEADING REFERENCE SYSTEM, AND AIRCRAFT”, which claims priority from German Patent Application No. 102021127228.9, filed on Oct. 20, 2021. The entire contents of each of the above-identified patent applications are incorporated herein by reference. The present invention relates to an electrical device with indirect lightning protection, in particular, for use in an attitude and heading reference system for air navigation or in an aircraft. High lightning protection requirements are especially in aviation of utmost importance. All installed devices must be provided with lightning protection of different magnitudes (threat level). In case of a high threat level and a large number of wired interface connections between the devices, this can lead to a space requirement in the individual devices that is not to be underestimated. Depending on the requirements and mechanical design, this outlay can take up to a third of the volume in a device. According to the lightning protection standard DIN EN 62305-4 (VDE 0185-3054), the risk to components from a lightning strike is classified into five threat levels or five lightning protection levels (LPL). In FIG. 6, corresponding characteristic data (the ratio of peak open-circuit voltage to peak short-circuit current at the calibration point Voc (in V)/Isc (in A) for different waveforms 3, 4 and 5a) is allocated to threat levels 1 to 5. Waveform 3 is an attenuated sine wave with a frequency of 1 MHz. Due to the attenuation, the wave still has a residual amplitude of approx. 50% after 5 periods. Waveforms 4 and 5a are a double-exponential pulse. They differ only in their duration. Waveform 4 has a rise time of 6.4 μs and a time to half value of 69 μs. Waveform 5a has a rise time of 40 us and a time to half value of 120 μs. Waveform 5a therefore has the highest energy content. For an adequate protection of electrical and electronic systems in aircraft against the effects of an electromagnetic lightning pulse, there are different combinations consisting of the following protective measures: earthing and potential equalization, spatial shielding, cable routing and cable shielding. The characteristic values of the protective measures must correspond to the selected threat or lightning protection level. Electronic devices or electrical devices, particularly those installed in aircraft, require an appropriate lightning protection to be protected against lightning strikes. If lightning strikes an externally mounted device (e.g., an electronic antenna) directly due to an unfavorable arrangement, this is referred to as a “direct lightning strike”. This case is not to be considered. If the strike occurs at an arbitrary point in the aircraft hull, the lightning pulse can couple capacitively from there to the interface cable by which the electronic devices communicate with one another. The lightning pulse moves as a wave along the cable and invades the device via the device plug. This is referred to as an “indirect lightning strike”. The protective measure required for this is called “indirect lightning protection”. Indirect lightning protection is usually achieved with standardized protective elements. The components for this are: gas arresters, varistors, suppressor diodes and resistors. They are used depending on the pulse energy. The basic principle is to convert the short-term pulse energy due to the indirect lightning strike into heat by means of these components, in particular, by means of a varistor/resistor or gas arrester. The calculations required for this are described in the technical literature (cf. Mel Clarke and Kent Walters (2018): “Lightning protection for aircraft electrical power and data communication systems”, publication Micronote 127, Microsemi Corporation). However, the current lightning protection measures in flying apparatus of all kinds have the following disadvantages. Firstly, the space required for the protective elements increases linearly with the number of externally wired interface connections connected to the device. In addition, the component surface increases exponentially as the threat level increases. This exponential proportion has a significant effect on the volume of the device. For example, if the energy is converted into heat with the aid of a resistor, the energy E and therefore the volume of the component increases in accordance with E=R×I2×t if the resistance R remains constant. In this case, I is the surge current of the lightning pulse that flows into the device on the interface line, and t is the duration of the pulse. In the graph, FIG. 7 shows the relationship between the component surface and the threat level, as well as the disadvantage of the current lightning protection measure. There is approximately a factor of 2.5 between ea