Apparatus and method for protecting an electrical device

Abstract

The invention relates to a method for protecting an electrical device comprising: - a contactor, - at least two current measurement sensors, - a pyrotechnic electrical switching device, the method comprising: - measuring the current intensity, - comparing the current intensity with two thresholds, and - if the intensity is between a first threshold and a second threshold, - sending a command to open the power contactor, - if the intensity is greater than the second threshold, - sending a command to trigger the opening of the pyrotechnic electrical switching device, - if the pyrotechnic electrical switching device has not opened, - comparing the current intensity with a third threshold, - if the current intensity is less than the third threshold, sending a command to open the contactor.

Description

Technical Field

[0001] This invention relates to the general field of protection of electrical installations, and more specifically to the protection of high-voltage DC power supply systems. Background Technology

[0002] Climate change is a major concern for many legislative and regulatory bodies worldwide. Specifically, countries have already implemented, are implementing, or will implement various restrictions on carbon emissions. In particular, an ambitious standard applies to both new and currently in-service aircraft, requiring the implementation of technological solutions to comply with existing regulations. Over the past few years, civil aviation has been committed to contributing to addressing climate change.

[0003] Technological research has enabled significant improvements in the environmental performance of aircraft. The applicant has considered factors influencing all stages of design and development to obtain aerospace components and products that consume less energy, are more environmentally friendly, and can be integrated into and used in civil aviation systems with a moderate environmental impact, thereby aiming to improve aircraft energy efficiency. Therefore, the applicant is continuously committed to minimizing its greenhouse gas emissions by using various methods and leveraging benign research and manufacturing processes to reduce its climate impact and thus reduce the environmental footprint of its business activities.

[0004] These supported R&D projects are particularly focused on using electric power technologies to provide thrust.

[0005] Against this backdrop, platforms used in eVTOL (electric vertical takeoff and landing) aircraft, eCTOL (electric conventional takeoff and landing) aircraft, and small aircraft for short-haul flights (air taxis) utilize new electric propulsion systems powered by high-voltage batteries. These high-voltage batteries contain a large amount of energy and typically have built-in fuse-based electrical protection devices that can disconnect the circuit in the event of a direct short circuit (i.e., when the two points of the short circuit come into direct contact). These fuses thus protect the power supply.

[0006] However, during overload or impedance short circuits (i.e., when the two points of the short circuit are connected through an impedance medium), there is a first gray area between the protection provided by the fuse and the protection provided by the power contactor, in which case the aircraft wiring is not protected. Furthermore, in the case of extremely high short-circuit currents, a second gray area exists, which may cause the contactor to disengage and damage itself, and also limits the current flowing through the fuse, delaying its triggering.

[0007] Therefore, fuses and contactors, which are typically found in high-voltage power grids (such as those powered by high-voltage batteries), cannot fully protect electrical devices between the power source and the load.

[0008] Therefore, there is a need for an electrical protection method that can protect electrical devices in systems powered by high-voltage DC batteries. Summary of the Invention

[0009] This invention relates to a method for protecting an electrical device located between an electrical power source and an electrical load, the electrical device comprising:

[0010] - Power contactor,

[0011] - At least two sensors, said at least two sensors being configured to measure the current flowing between an electrical power source and a load.

[0012] - A pyrotechnic power-off device, wherein the pyrotechnic power-off device is connected in series with a power contactor.

[0013] The method includes:

[0014] -Measure the current in amperes flowing through an electrical device.

[0015] - Compare the ampere value of the current with a first threshold and a second threshold, wherein the second threshold is greater than the first threshold, and

[0016] -If the ampere number is between the first threshold and the second threshold

[0017] Then send a first command to disconnect the power contactor.

[0018] -If the ampere number is greater than the second threshold.

[0019] - Then send the first command to trigger the disconnection of the pyrotechnic power-off device.

[0020] -If the pyrotechnic power-off device does not disconnect after the first command used to trigger it.

[0021] Then the current in amperes is compared with a third threshold representing the breaking capacity of the power contactor.

[0022] If the current in amperes is less than the third threshold, a second command is sent to disconnect the power contactor.

[0023] This pyrotechnic power-off device, commonly known as a pyrotechnic fuse, can disconnect the power circuit through the fusing effect when the current is high (e.g., up to 5kA), or disconnect the power circuit through the mechanical breakage of a pyrotechnic actuator (located within the pyrotechnic fuse) when the current is low.

[0024] Therefore, thanks to the device of the present invention, the combination of the pyrotechnic fuse and the power contactor enables the power distribution line to be disconnected immediately in the event of a short circuit or overload.

[0025] Specifically, in the event of an overload, for example, when the current measured by the sensor is between the rated current and 1 kA, the fault current can be seen from the current measurement value collected by the sensor, and the controller can command the contactor to disconnect; while in the event of a short circuit, for example, when the current measured by the sensor is between 1 kA and 5 kA, the pyrotechnic fuse will be disconnected to protect the electrical equipment.

[0026] According to some embodiments, if the current in amperes is greater than the third threshold, the method includes disconnecting the fuse of the electrical device.

[0027] According to some embodiments, the method includes:

[0028] -If the contactor does not disconnect after the first command is sent to disconnect the power contactor,

[0029] Then a second command is sent to trigger the disconnection of the pyrotechnic power-off device.

[0030] According to some embodiments, the method includes:

[0031] - If the pyrotechnic power-off device (130) is not disconnected after a second command is sent to trigger the disconnection of the pyrotechnic power-off device (130), then the fuse of the electrical device is disconnected.

[0032] This fuse enables additional protection for electrical installations in the event of a severe short circuit.

[0033] According to some embodiments, the method includes:

[0034] - If the pyrotechnic fuse does not disconnect after a second command is sent to trigger the disconnection of the pyrotechnic power-off device, then disconnect the fuse of the electrical device.

[0035] According to some embodiments, the disconnection of the pyrotechnic power-off device can be performed after a first delay.

[0036] According to some embodiments, the disconnection of the power contactor can be performed after a second delay.

[0037] The present invention also relates to an electrical device for protecting an electrical apparatus intended to be placed between an electrical power source and an electrical load, the electrical power source including a positive terminal and a negative terminal, the device comprising:

[0038] - A power contactor, the power contactor including a first contact and a second contact, the first contact being intended to be connected to the positive terminal of an electrical power source, and the second contact being intended to be connected to the negative terminal of an electrical power source;

[0039] - At least two sensors, said at least two sensors being configured to measure the current flowing between an electrical power source and an electrical load;

[0040] - A pyrotechnic power-off device, wherein the pyrotechnic power-off device is connected in series with a power contactor, and

[0041] The controller is configured to receive the current measured by the sensor and is configured to:

[0042] -Measure the ampere current flowing through an electrical device;

[0043] - Compare the ampere number of the current with a first threshold and a second threshold, wherein the second threshold is greater than the first threshold; and

[0044] -If the ampere number is between the first threshold and the second threshold

[0045] -Then send a first command to disconnect the power contactor;

[0046] -If the ampere number is greater than the second threshold.

[0047] Then, a first command is sent to trigger the disconnection of the pyrotechnic power-off device.

[0048] -If the pyrotechnic power-off device does not disconnect after the first command used to trigger it.

[0049] -Then the current in amperes is compared with a third threshold representing the breaking capacity of the power contactor (120).

[0050] If the current in amperes is less than the third threshold, a second command is sent to disconnect the power contactor.

[0051] The present invention also relates to a high-voltage DC (direct current) distribution board, which includes protection devices and circuitry for supplying power to electrical loads according to at least one embodiment of the present invention.

[0052] The present invention also relates to an aircraft comprising an electrical protection device according to at least one embodiment of the present invention or a power distribution board according to at least one embodiment of the present invention.

[0053] Other features and advantages of the invention will become apparent from the following description with reference to the accompanying drawings, which illustrate exemplary embodiments of the invention but do not limit it in any way. Attached Figure Description

[0054] Figure 1 An electrical protection device according to an embodiment of the present invention is shown schematically and in part.

[0055] Figure 2 Schematic illustration of a control according to an embodiment of the present invention Figure 1 Methods for protecting equipment.

[0056] Figure 3 A graph showing the change in amperes over time in different components affected by an electrical fault. Detailed Implementation

[0057] In this specification, the term "pyrotechnic fuse" refers to a pyrotechnic power-off device.

[0058] Figure 1 An electrical protection device 100 according to an embodiment of the present invention is shown schematically and in part.

[0059] The device 100 enables electrical protection for an electrical device placed between the positive terminal 1011 and the negative terminal 1012 of the electrical power supply 101 and the electrical load 102. The protected electrical device consists of the device 100 and the wiring harness connecting the electrical load 102 and the electrical power supply 101 to the device 100.

[0060] Device 100 includes a power contactor 120, a pyrotechnic power-off device 130 (more commonly referred to as a pyrotechnic fuse), two sensors 161 and 162, a pre-charging circuit 150, a relay 140, and a controller 110.

[0061] The power contactor 120 and the pyrotechnic fuse 130 are assembled in series.

[0062] The power contactor 120 includes a first contact 121 connected to the positive terminal 1011 of the electrical power supply 101 and a second contact 122 connected to the negative terminal 1012 of the electrical power supply 101. It enables the interruption of the flow of current between the electrical power supply 101 and the electrical load 102.

[0063] For example, the power contactor 120 is particularly characterized by its ability to disconnect within a maximum of 20 ms when the current is below its breaking power. This time depends primarily on the mechanical limitations of the components.

[0064] Sensors 161 and 162 are configured to measure the current flowing between electrical power supply 101 and power contactor 120.

[0065] Sensors 161 and 162 can be different types of sensors, such as, for example, but not limited to, Hall effect sensors, or LEM sensors or NieR effect sensors.

[0066] The pre-charge circuit 150 includes input terminals 151 and 152 located between the electrical power supply 101 and the power contactor 120, and output terminals 153 and 154 connected to the electrical load 102. This allows for limiting the current flowing to the electrical load 102 before the power contactor 120 is closed.

[0067] Relay 140 is connected to input terminals 151 and 152 of precharge circuit 150 so that it can be connected to or disconnected from the main grid.

[0068] The pyrotechnic fuse 130 is connected to the negative terminal 1012 of the electrical power supply 101 and the second contact 122 of the power contactor 120.

[0069] For example, the pyrotechnic fuse 130 is particularly characterized by its ability to withstand currents of several thousand amperes and to disconnect within a maximum of 3 ms. This time depends primarily on fault detection and on the ignition of the pyrotechnic device.

[0070] The controller 110 is configured to receive current measurements from sensors 161 and 162 and implement a reference... Figure 2 The method described.

[0071] The device 100 may also include a fuse connected to the positive terminal 1011 of the electrical power supply 101 and the first contact 121 of the power contactor 120. This fuse enables protection of the electrical power supply 101 under high current conditions (e.g., between 5 kA and 50 kA) and provides more diverse electrical protection compared to the other devices mentioned (power contactor 120 and pyrotechnic fuse 130).

[0072] Device 100 may also include a magnetic probe integrated into pyrotechnic fuse 130. This magnetic probe enables the detection of short circuits and triggers pyrotechnic fuse 130 to disconnect, thereby protecting the electrical device. This allows for the detection of abnormal currents different from those of current sensors 161 and 162, thereby improving the safety of device 100.

[0073] Figure 2 Schematic representation of an embodiment of the present invention Figure 1 The flowchart shows the control method implemented by the protection device 110.

[0074] Before performing the steps of this method, it is assumed that the power contactor 120 and the pyrotechnic fuse 130 are connected to the electrical load 102.

[0075] The method includes: Step E1, measuring the current flowing through the protection device 100 using sensors 161 and 162, and comparing the measured current I with a first current threshold S1. When the measured current in amperes is greater than S1, this ampere value is monitored to ensure it remains between threshold S1 and a second threshold S2, step E2. When the measured ampere value I exceeds threshold S2, the pyrotechnic fuse is triggered to disconnect, step E4. This disconnection is triggered only after, for example, 5 ms, step E3. This delay may be related to the following:

[0076] - Fault detection time;

[0077] - The disconnection time of the pyrotechnic fuse, for example, 3 ms as previously indicated.

[0078] The pyrotechnic fuse can be triggered in at least two ways. According to a first embodiment, the pyrotechnic fuse may include a magnetic sensor, which independently triggers its tripping. According to a second embodiment, it may be commanded by a controller 110 or an external system. If the pyrotechnic fuse trips, step E5, then the method ends. It should be noted that the pyrotechnic fuse must be replaced after tripping, for example, during maintenance operations.

[0079] If the pyrotechnic fuse does not trip (e.g., due to a malfunction), in step E5, the change in ampere I is detected during step E6, and if this ampere is less than the ampere that would cause contactor 120 to trip (e.g., 4000A), then a command is issued to trip contactor 120, in step E7.

[0080] In reality, it is impossible to measure currents up to 4000A. It can be ensured during the system design phase that, for current values ​​exceeding the contactor's capacity threshold, the fuse will disconnect the circuit before the contactor.

[0081] The term "circuit break" should be understood to mean that the contactor's protection is no longer operational, for example, due to a current exceeding 4000A, the contactor may be stuck under the influence of a high current ampere and unable to disconnect. Otherwise, if the ampere is greater than the ampere that would cause contactor 120 to fail, the method continues to step E9, where the fuse trips.

[0082] If contactor 120 disconnects after the instruction to disconnect it, the method terminates at step E8. Otherwise, if contactor 120 does not disconnect, the method continues to step E9, where the fuse is triggered. The method terminates after step E9.

[0083] If, during step E2, the measured ampere is greater than S1 but remains less than S2, the method continues to step E11 after a delay of, for example, 200 ms (step E10). This delay is preferably adjustable and can be adjusted according to the characteristics of the device. During step E11, a command is sent to disconnect contactor 120, as in the previous step E7. If contactor 120 disconnects after the command for disconnecting contactor 120, the method terminates at step E12. Otherwise, if contactor 120 does not disconnect, the method continues to step E13, where a command is sent to disconnect pyrotechnic fuse 130. If pyrotechnic fuse 130 disconnects, the method terminates at step E14. Otherwise, if pyrotechnic fuse 130 does not disconnect, the method continues to step E9, where the fuse is triggered.

[0084] For example, a first current threshold S1 is between the rated current and 1 kA, while a second current threshold S2 is between 1 kA and 5 kA. According to another example, the first current threshold S1 is equal to the rated current, while the second current threshold S2 is equal to 1 kA. The 1 kA threshold is adjustable, for example, as a function of the device's characteristics and the contactor's capability related to operating conditions (especially altitude).

[0085] The 5 kA threshold can depend on the capability of the pyrotechnic device.

[0086] Another subject of this invention is a high-voltage DC (direct current) distribution board comprising the protection device of this invention and a circuit for energizing an electrical load. This electrical energizing circuit is an electronic pre-charging system that enables the charging of the electrical load's capacitance while limiting current, thereby avoiding current spikes (several thousand amperes) associated with grid connection of the capacitors of the high-voltage load. Compared to conventional resistive systems, this system enables protection of the power grid during switching while optimizing quality and size.

[0087] In the case of an electrically propelled aircraft, the board can therefore be connected to different electrical loads of the aircraft at its output terminals and to the aircraft's electrical power source at its input terminals. The electrical power source could be, for example, a high-voltage battery, while the electrical load could be an electric motor.

[0088] It can also be connected to the global aircraft control system and the aircraft emergency system. Therefore, the pyrotechnic fuse can be controlled, for example, by the aircraft's global system and / or by the emergency system.

[0089] Furthermore, the described distribution board enables the optimized allocation of electrical components for protection devices and power supply circuits, as well as the different electrical protections for the components present on the board.

[0090] In addition, excessive current amperes can be measured or detected by using a magnetocurrent probe integrated into the pyrotechnic fuse.

[0091] Figure 3 The variations in electrical protection curves according to certain embodiments and the main requirements for different components are illustrated. Figure 3 In the graph, the horizontal axis represents time, and the vertical axis represents amperes. The time and ampere scales are logarithmic. It should be understood that the values ​​shown on these curves are given only as examples.

[0092] The curves show the acceptable ampere numbers for different components of the aircraft during corresponding time periods, indicated by time along the horizontal axis. It can be seen that different components are capable of withstanding higher ampere numbers over shorter durations compared to lower ampere numbers.

[0093] The "fuse" curve represents an approximation of the fuse curve of the power supply fuse integrated into the battery.

[0094] The “Connection 2” curve represents the acceptable energy limit of a Type 2 cable without any damaging effects (i.e., the so-called “lossless” curve), expressed in amperes over time. For example, a Type 2 connection can withstand amperes slightly above 10,000 A for 300 ms and can withstand amperes above the threshold S2 or 380 A for a continuous period of time.

[0095] The “motor” curve shows the acceptable energy limit in a motor. Beyond this limit, the motor will no longer be able to withstand the energy (e.g., the casing is punctured), and the failure may propagate to its environment.

[0096] The "motor envelope" point represents the operating point of the motor within its functional rating.

[0097] The figure also illustrates the thresholds S1 and S2 implemented in this invention. Thresholds S1 and S2 can be determined such that no component is allowed to be exposed to amperes exceeding its tolerance during time t. According to... Figure 3 In the example, S2 is set to 350 amperes and S1 is set to 250 amperes.

[0098] The threshold S2 is set such that it is less than the smoke curve of line 2, i.e., the "line 2" curve.

[0099] The threshold S1 is set such that it is higher than the operating current level of the motor and corresponds to the so-called "overload" threshold.

[0100] The maximum amperage height of the amperage curves for pyrotechnic fuses and contactors corresponds to the maximum capacity of the component. According to... Figure 3The examples given show that these values ​​correspond to 5000A for pyrotechnic fuses and 4000A for contactors.

[0101] Wiring 2 is protected by a pyrotechnic fuse and a contactor, and the threshold S2 can be determined as follows: it is sufficient to protect wiring 2 from any fire. It can be seen that wiring 2 can withstand amperes slightly greater than the threshold S2 for 1000 seconds or longer. Therefore, wiring 2 is effectively protected by both the contactor and the pyrotechnic fuse.

Claims

1. A method for protecting an electrical device located between an electrical power source (101) and an electrical load (102), the electrical device comprising: - Power contactor (120) - At least two sensors (161, 162) are configured to measure the current flowing between the electrical power source and the load (102). - A pyrotechnic power-off device (130), wherein the pyrotechnic power-off device (130) is connected in series with a power contactor (120). The method includes: -Measure the current in amperes flowing through an electrical device. - The ampere number of the current is compared with a first threshold (S1) and a second threshold (S2), wherein the second threshold (S1) is greater than the first threshold (S2), and -If the ampere number is between the first threshold (S1) and the second threshold (S2), Then send a first command to disconnect the power contactor (120). -If the ampere number is greater than the second threshold (S2). -Then a first command is sent to trigger the disconnection of the pyrotechnic power-off device (130). -If the pyrotechnic power-off device (130) does not disconnect after the first command used to trigger it, -Then the current in amperes is compared with a third threshold representing the breaking capacity of the power contactor (120). If the current in amperes is less than the third threshold, a second command is sent to disconnect the power contactor (120).

2. The method according to claim 1, comprising: If the current in amperes is greater than the third threshold, then the fuse of the electrical device is disconnected.

3. The method according to any one of the preceding claims, comprising: -If the contactor does not disconnect after the first command to disconnect the power contactor (120) is sent, - Then send a second command to trigger the disconnection of the pyrotechnic power-off device (130).

4. The method according to claim 3, comprising: - If the pyrotechnic power-off device (130) is not disconnected after a second command is sent to trigger the disconnection of the pyrotechnic power-off device (130), then the fuse of the electrical device is disconnected.

5. The method according to any one of the preceding claims, wherein the disconnection of the pyrotechnic power-off device (130) is operable after a first delay.

6. The method according to any one of the preceding claims, wherein the disconnection of the power contactor (120) is operable after a second delay.

7. An electrical device (100) for protecting an electrical apparatus intended to be placed between an electrical power source (101) and an electrical load (102), the electrical power source (101) comprising a positive terminal (1011) and a negative terminal (1012), the device comprising: - A power contactor (120) includes a first contact (121) and a second contact (122), the first contact (121) being intended to be connected to the positive terminal (1011) of an electrical power source, and the second contact (122) being intended to be connected to the negative terminal (1012) of an electrical power source. - At least two sensors (161, 162) are configured to measure the current flowing between the electrical power source (101) and the electrical load (102); - A pyrotechnic power-off device (130), wherein the pyrotechnic power-off device (130) is connected in series with a power contactor (120), and A controller (110) is configured to receive current measured by a sensor and is configured to: -Measure the current in amperes flowing through an electrical device. - The ampere number of the current is compared with a first threshold (S1) and a second threshold (S2), wherein the second threshold (S2) is greater than the first threshold (S1), and -If the ampere number is between the first threshold (S1) and the second threshold (S2), Then send a first command to disconnect the power contactor (120). -If the ampere number is greater than the second threshold (S2). -Then a first command is sent to trigger the disconnection of the pyrotechnic power-off device (130). -If the pyrotechnic power-off device (130) does not disconnect after the first command used to trigger it, -Then the current in amperes is compared with a third threshold representing the breaking capacity of the power contactor (120). If the current in amperes is less than the third threshold, a second command is sent to disconnect the power contactor (120).

8. A high-voltage DC power distribution board, comprising the protection device according to claim 7 and a circuit for supplying power to electrical loads.

9. An aircraft comprising the electrical protection device according to claim 7 or the power distribution board according to claim 8.

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