Method for detecting a lightning strike by exceeding a measurement gradient

Abstract

Method for detecting a lightning strike by exceeding a measurement gradient. Method (100) for detecting a lightning strike on electrical measurements of an aircraft engine control system comprising: - determining (101) a detection threshold for a lightning strike on the electrical measurements of the engine control system, the detection threshold being a maximum gradient between two electrical measurements, the maximum gradient being an absolute difference between two electrical measurements; and - comparing (102) the gradients between two electrical measurements of a set of N consecutive electrical measurements with respect to the detection threshold and detecting (103) a lightning strike on the i-th measurement if the gradient between the i-th measurement and the other measurements is greater than or equal to the detection threshold, N being an integer greater than or equal to 2 and i being between 1 and N. Figure for the abstract: Fig. 1

Description

Title of the invention: Method for detecting a lightning strike by exceeding a measurement gradient Technical field

[0001] The present invention relates to the general field of lightning strike detection, and more particularly to the detection by the engine control system of an aircraft of a lightning strike. Prior art

[0002] Aircraft engines are subjected to a severe lightning environment, including lightning strikes. In the event of a lightning strike on an aircraft, electrical measurements taken from the engine or aircraft sensors may be disrupted for a short time. These disruptions can nevertheless affect engine regulation and thus influence engine thrust.

[0003] It is therefore desirable to have a method for detecting a lightning strike that allows these strikes to be accommodated and reduces disturbances to the engine thrust, in order to improve the robustness of the aircraft engine control system in the face of these strikes. Statement of the invention

[0004] The invention relates to a method for detecting a lightning strike on electrical measurements of an aircraft engine control system comprising: - the determination of a detection threshold for a lightning strike on the electrical measurements of the engine control system, the detection threshold being a maximum gradient between two electrical measurements, the maximum gradient being a difference in absolute value between two electrical measurements; and - the comparison of gradients between two electrical measurements of a set of N consecutive electrical measurements with respect to the detection threshold and the detection of a lightning strike on the i-th measurement if the gradient between the i-th measurement and the other measurements is greater than or equal to the detection threshold, N being an integer greater than or equal to 2 and i being between 1 and N.

[0005] The method of the invention thus makes it possible to detect lightning strikes. Furthermore, by defining a detection threshold, it makes it possible to detect lightning strikes that could disrupt the system and to disregard the measurement affected by the lightning strike in order to reduce disturbances to the thrust.

[0006] Moreover, since the detection is done by the regulation system, it does not require the presence of a specific sensor and therefore makes it possible to limit the size of the engine in the aircraft.

[0007] According to another embodiment of the invention, the method includes the suppression of the N measurements if a lightning strike has been detected on at least one of the N measurements.

[0008] Thus, as soon as a lightning strike is detected on one measurement among a cycle of N measurements, all N measurements are invalidated.

[0009] According to another embodiment of the invention, the method includes supplying the (il)th measurement to the aircraft engine control system if a lightning strike has been detected on the i-th measurement, with i between 2 and N.

[0010] According to another embodiment of the invention, the aircraft engine control system includes a filter with X inputs, X being an integer strictly less than N, and the method includes supplying the filter of the control system with X measurements, among the N measurements, of which no lightning impact has been detected.

[0011] Thus, only measurements unaffected by the lightning strike are provided to the filter.

[0012] According to another particular feature of the invention, N is equal to 4.

[0013] Another object of the invention is an aircraft engine control system comprising: - a sensor configured to measure an electrical quantity; - an analog-to-digital converter configured to convert the sensor measurement into a digital signal; and - a programmable digital circuit configured to implement the process according to the invention on the measurements converted by the converter.

[0014] According to one embodiment of the invention, the control system also includes a filter placed in parallel with the programmable digital circuit and configured to reduce noise and improve the accuracy and resolution of the digital signal from the converter.

[0015] According to another embodiment of the invention, the control system also includes a filter placed at the output of the programmable digital circuit and configured to reduce noise and improve the accuracy and resolution of the measurements provided by the programmable digital circuit. Brief description of the drawings

[0016] Other features and advantages of the present invention will become apparent from the description given below, with reference to the attached drawings which illustrate examples of embodiment without any limiting character.

[0017] [Fig-1] Fig. 1 represents, schematically, a detection method according to an embodiment of the invention.

[0018] [Fig.2] Fig.2 represents, schematically and partially, a regulation system for an aircraft engine according to an embodiment of the invention.

[0019] [Fig. 3] [Fig. 3] schematically and partially represents an aircraft engine control system according to another embodiment of the invention. Description of embodiments

[0020] Fig. 1 schematically represents a flowchart of the method for detecting a lightning strike on electrical measurements of an aircraft engine control system according to an embodiment of the invention.

[0021] The detection method 100 includes determining 101 a detection threshold for a lightning strike on the electrical measurements of the motor control system. This detection threshold makes it possible to characterize the effect of lightning on the electrical measurements at the input of the motor control system and to determine whether the measurement affected by the lightning strike should be taken into account by the control system.

[0022] The effect of lightning on the measurements depends in particular on the following elements: - the waveform and repetition sequence of lightning: the DO-160 standard defines, for example, all the waveforms and repetition sequences that can be applied to test the resistance of a system to a lightning strike; - the direction of lightning injection: the waveforms of the lightning strike can be injected in a positive or negative direction. Thus, depending on the lightning protection systems implemented in the control system, the effect of lightning on electrical measurements can differ depending on the direction of lightning injection; - the injection time: the electrical measurement interfaces of the control system may have different measurement methods, and lightning strikes are generally very short. The relationship between the start of the lightning strike and the start of the measurement at the associated interface is therefore important in estimating the effect of lightning on this measurement; and - The measurement value at the time of the lightning strike: the value measured by the measuring interface at the time of the lightning strike can influence the effect of the lightning. Therefore, different values ​​within the measurement validity range must be tested to properly characterize the effect of lightning on this interface.

[0023] By studying these effects, it is possible to predict the influence of lightning on the electrical measurements used by the engine control system. This allows us to determine the detection threshold for whether a measurement affected by a lightning strike should be taken into account by the system.

[0024] The detection threshold that is determined in step 101 is a maximum gradient between two electrical measurements, that is to say a maximum difference in absolute value between the two measurements.

[0025] For example, if the electrical measurement is a current measurement, the detection threshold could be a difference of 2 A between two current measurements.

[0026] According to another example, if temperatures are measured, the maximum gradient, and therefore the detection threshold, can be deduced by analyzing motor recordings.

[0027] In addition, for a variable geometry, the detection threshold can also be determined according to the limits of the motor control system, for example, physically, it is not possible to open or close a cylinder faster than the system allows.

[0028] The method 100 then includes the comparison 102 between the determined detection threshold and gradients between two electrical measurements for a set of N measurements, N being an integer greater than or equal to 2. This means that for an i-th measurement, i being an integer between 1 and N, all the gradients between the i-th measurement and the other Nl measurements at the detection threshold are compared.

[0029] If all the gradients between the Nl measurements and the i-th measurement are greater than or equal to the detection threshold, then the i-th measurement is considered to have been struck by lightning, and therefore a lightning strike is detected for this i-th measurement (step 103).

[0030] If at least one of the gradients between the Nl measurements and the i-th measurement is less than the detection threshold, then it is considered that the i-th measurement has not been affected by lightning, and therefore no lightning strike is detected (step 104).

[0031] If a lightning strike is detected on the i-th measurement, the i-th measurement is invalidated (step 105). This means that the aircraft engine control system will not take this measurement into account.

[0032] Then, following the detection 103 of a lightning strike on the i-th measurement and the invalidation 105 of the i-th measurement, the method may include one of the following steps: - Step 106: The Nl other measures among the N measures are removed, so the regulatory system will not take any of the N measures into account; or - Step 107: If the i-th measurement struck by lightning is not the first of the N measurements (i.e., if i is greater than or equal to 2), then the process provides the (il)-th measurement to the control system, the (il)-th measurement being a measurement not struck by lightning. Thus, the control system will take into account the last valid measurement, i.e., not struck by lightning, among the N measurements if a lightning strike is detected among the N measurements. If the measurement struck by lightning is the first of the N measurements, then the process does not provide any measurement to the control system, which is equivalent to applying step 106 of process 100; Or - Step 108: The process provides only X measurements (X being an integer strictly less than N) not affected by lightning to the control system, and more specifically, it provides these X measurements to a filter comprising X inputs present in the control system. If the process has detected several measurements affected by lightning and there are fewer than X measurements not affected by lightning among the N measurements, then step 106 or 107 of the process will be applied.

[0033] An example of implementation of the detection method 100 is now described for a set of four measurements, i.e. N = 4.

[0034] After determining the detection threshold, the process will determine whether the first, second, third and / or fourth measurement has been affected by lightning.

[0035] Thus, for the first measurement, the method compares, with respect to the detection threshold, the absolute difference between the first and second measurements, the absolute difference between the first and third measurements, and the absolute difference between the first and fourth measurements. If all three differences are greater than or equal to the detection threshold, then a lightning strike is detected in the first measurement, and in this case, the first measurement is invalidated. If any of the differences is less than the detection threshold, then no lightning strike is detected, and the first measurement is considered valid.

[0036] For the second measurement, the method compares, with respect to the detection threshold, the absolute difference between the second and first measurements, the absolute difference between the second and third measurements, and the absolute difference between the second and fourth measurements. If all three differences are greater than or equal to the detection threshold, then a lightning strike is detected in the second measurement, and in this case, the second measurement is invalidated. If any of the differences is less than the detection threshold, then no lightning strike is detected, and the second measurement is considered valid.

[0037] For the third measurement, the method compares, with respect to the detection threshold, the absolute difference between the third and first measurements, the absolute difference between the third and second measurements, and the absolute difference between the third and fourth measurements. If all three differences are greater than or equal to the detection threshold, then a lightning strike is detected in the third measurement, and in this case, the third measurement is invalidated. If any of the differences is less than the detection threshold, then no lightning strike is detected, and the third measurement is considered valid.

[0038] For the fourth measurement, the method compares, with respect to the detection threshold, the difference in absolute value between the fourth and first measurements, the difference in The absolute value between the fourth and second measurements and the absolute difference between the fourth and third measurements are considered. If all three differences are greater than or equal to the detection threshold, then a lightning strike is detected on the fourth measurement, and in this case, the fourth measurement is invalidated. If any of the differences are less than the detection threshold, then no lightning strike is detected, and the fourth measurement is considered valid.

[0039] Next, if one of the first, second, third and / or fourth measurements has been invalidated due to the detection of a lightning strike, the method may either: - delete all measurements; or - provide the first measurement to the control system, if the lightning strike was detected on the second measurement, or provide the second measurement if the lightning strike was detected on the third measurement, or provide the third measurement if the lightning strike was detected on the fourth measurement; or - provide X valid measurements, with X an integer less than 4, to the filter present in the control system and comprising X inputs.

[0040] Fig. 2 represents, schematically and partially, a control system 200 of an aircraft engine according to a first embodiment of the invention.

[0041] The control system 200 includes a sensor 201 configured to measure an electrical quantity connected to an analog-to-digital converter 202 which converts the measurement from the sensor into a digital signal, the measurement of the electrical quantity being provided to the converter 202 in the form of an analog electrical signal.

[0042] The system 200 also includes a filter 203 and a programmable digital circuit 206 connected in parallel and located at the output of the converter 202. The filter 203 is configured to reduce noise and improve the accuracy and resolution of the digital signal from the converter 202. The programmable digital circuit 206 is configured to implement the method according to the invention. Elements 204 and 205 of [Fig. 2] are part of the programmable digital circuit 206 and enable the implementation of the method of the invention.

[0043] Thus, the converter 202 provides the N converted measurements to the filter 203 and the programmable digital circuit 206. The filter 203 thus provides at its output the N filtered measurements, while the programmable digital circuit 206 first detects (element 204) the valid measurements among the N measurements (if a lightning strike has been detected by the programmable digital circuit, it is also possible that the circuit will not provide any measurement at its output in accordance with the method of the invention), then it combines them with the measurements provided by the filter 203 to provide at its output (out of the element 205) the valid and filtered measurements which will be taken into account by the control system 200 to determine the thrust of the engine.

[0044] The filter 203 can be an external or internal element of the programmable digital circuit 206. In this first embodiment, it is external to the programmable digital circuit 206.

[0045] Figure 3 represents, schematically and partially, a regulation system for an aircraft engine according to a second embodiment of the invention.

[0046] The control system 300 includes a sensor 301 configured to measure an electrical quantity connected to an analog-to-digital converter 302 which converts the measurement from the sensor into a digital signal, the measurement of the electrical quantity being provided to the converter 302 in the form of an analog electrical signal.

[0047] The system 300 also includes a programmable digital circuit 304 connected to the converter 302 and a filter 303 connected to the output of the programmable digital circuit 304. The programmable digital circuit 204 is configured to implement the method according to the invention and thus select valid measurements from among the N measurements converted and provided by the converter 302, N being an integer greater than or equal to 2. The filter 303 comprises X inputs with X an integer less than N, and it is configured to reduce noise and improve the accuracy and resolution of the valid measurements selected by the programmable digital circuit 304. The measurements provided at the output of the filter 303 are therefore the valid and filtered measurements taken into account by the control system 300 to determine the engine thrust.

[0048] Regardless of the embodiment, the electrical quantity measured by the sensor 201, 301 can be an electric current, an electric voltage, an electrical resistance, a time or a frequency.

[0049] Regardless of the embodiment, the programmable digital circuit can be a wired logic electronic circuit, or a microcontroller, or even a programmable logic circuit (FPGA, “Field-programmable Gate Array” in English).

Claims

Claims

1. A method for detecting (100) a lightning strike on electrical measurements of a control system (200, 300) of an aircraft engine comprising: - determining (101) a threshold for detecting a lightning strike on the electrical measurements of the control system of the engine, the detection threshold being a maximum gradient between two electrical measurements, the maximum gradient being a difference in absolute value between two electrical measurements; and - comparing (102) the gradients between two electrical measurements of a set of N consecutive electrical measurements with respect to the detection threshold and detecting (103) a lightning strike on the i-th measurement if the gradient between the i-th measurement and the other measurements is greater than or equal to the detection threshold, N being an integer greater than or equal to 2 and i being between 1 and N.

2. A detection method according to claim 1, comprising deleting (106) the N measurements if a lightning strike has been detected on at least one of the N measurements.

3. A detection method according to claim 1, comprising providing (107) the (il)-th measurement to the aircraft engine control system if a lightning strike has been detected on the i-th measurement, with i between 2 and N.

4. Detection method according to claim 1, in which the regulation system (300) of the aircraft engine comprises a filter (303) with X inputs, X being an integer strictly less than N, and the method comprises providing (108) to the filter of the regulation system X measurements, among the N measurements, of which no lightning strike has been detected.

5. A detection method according to any one of claims 1 to 4, wherein N is equal to 4.

6. Regulation system (200, 300) of an aircraft engine comprising: - a sensor (201, 301) configured to measure an electrical quantity; - an analog-digital converter (202, 302) configured to convert the measurement of the sensor into a digital signal; and - a programmable digital circuit (204, 304) configured to implement the method according to any one of claims 1 to 5 on the measurements converted by the converter.

7. A control system (200) according to claim 6, also comprising a filter (203) placed in parallel with the programmable digital circuit (204) and configured to reduce noise and improve the accuracy and resolution of the digital signal from the converter.

8. A control system (300) according to claim 6, also comprising a filter (303) placed at the output of the programmable digital circuit (304) and configured to reduce noise and improve the accuracy and resolution of the measurements provided by the programmable digital circuit.

9. An aircraft engine comprising a control system (300) according to any one of claims 6 to 8.

10. An aircraft comprising an engine according to claim 9.

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