Device and method for initiating electric arc on electronic device, in particular power electronic device

Abstract

The invention relates to a device for initiating an electric arc (9) in an electronic device (10) for testing the behavior of the electronic device under the action of such an electric arc and / or under the action of an electrical fire resulting from an electric arc, the initiating device (9) comprising:-a transistor (19) comprising two power pins (22a, 22b) and a control pin (21), the power pins are electrically connectable to a first electrical trace and a second electrical trace of the equipment (10); and-a control circuit (20) of the transistor configured to apply a control signal to the control pin (21) of the transistor (19), the control signal being able to cause an irreversible closing of the transistor (19) when the first and second traces (13a, 13b) are energized and being able to cause a short circuit of the transistor (19), and thus generating an arc.

Description

Technical Field

[0001] This invention relates to the field of testing the behavior of electronic equipment under the influence of electric arcs, electrical short circuits, and electrical fires generated therefrom.

[0002] More specifically, this invention relates to a device for initiating an electric arc in electronic equipment, particularly electrical equipment.

[0003] The present invention also relates to a method for initiating a related electric arc.

[0004] This invention is particularly advantageous for use in the aerospace field, but it is also applicable to any other electrical field. Background Technology

[0005] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, states have already implemented, are implementing, or will implement various carbon emission limits. In particular, an extremely stringent standard applies to both new and currently in-service aircraft, requiring the implementation of technological solutions to bring them into compliance with current regulations. For several years, the civil aviation industry has been actively contributing to addressing climate change.

[0006] Technological research has significantly improved the environmental performance of aircraft. The applicant has considered influencing factors at all design and development stages to obtain more energy-efficient, more environmentally friendly aircraft components and products whose integration and use in civil aviation have a milder environmental impact, thereby improving aircraft energy efficiency.

[0007] Therefore, the applicant is committed to reducing negative impacts on the climate by using and operating benignly developed and manufactured methods and processes that reduce greenhouse gas emissions to the minimum possible, thereby reducing the environmental footprint of its activities.

[0008] These ongoing research and development efforts specifically focus on reducing the weight of next-generation aircraft engines and aircraft through the use of materials and lighter airborne equipment, the development and use of electric technologies to ensure propulsion, and aviation biofuels as a necessary complement to technological progress.

[0009] In the aviation sector, in particular, there is a trend toward the electrification of aircraft with architectures that can be powered by high-voltage direct current (HVDC) and / or high-voltage alternating current (AC) to supply propellant-loaded and / or non-propellant-loaded power. These architectures incorporate a certain amount of electronic power conversion equipment (AC / AC, AC / DC, DC / DC, DC / AC), which should be qualified. More generally, since aircraft embed a large amount of electronic equipment integrated into architectures using high-voltage networks, this electronic equipment should be qualified under its operating conditions. The same applies to electronic equipment in other sectors, particularly the service sector and the automotive industry.

[0010] In particular, the operational safety requirements of electronic equipment must be verified.

[0011] In particular, the strength and response of electronic equipment must be certified in accordance with this requirement during the occurrence of an electric arc (which could lead to an electrical fire).

[0012] To facilitate such electronic equipment testing activities, it is necessary to enable test operators to reliably, repeatably, and safely generate electric arcs.

[0013] Therefore, devices and methods for initiating electric arcs have been developed.

[0014] Figure 1 Specifically shown is an arc initiation device 1, which is typically used to initiate an electric arc under laboratory conditions.

[0015] Device 1 includes a circuit 2 that connects a power source 3, a power contactor 4, and a pair of electrical strips 6 and 7. The power contactor can be actuated by an actuator 5 (e.g., an auxiliary circuit) and is directly connected in series downstream of the source 3. The first strip 6 is connected in series upstream of the source 3, and the second strip 7 is connected in series downstream of the contactor 4. Device 1 also includes a fusible wire 8 that connects the two electrical strips 6 and 7 together. Compared to the other electrical conductors of the device (e.g., electrical strips 6 and 7), the fusible wire is a small-sized wire, and its dimensions are designed to perform a fusing function by a certain level of current flowing through it.

[0016] The fusible wire 8 forms part of a conductive material (such as copper, tin, iron, or any other conductive material).

[0017] Before device 1 is started, the entire circuit 2 is initially de-energized because contactor 4 occupies the open position of circuit 2.

[0018] During the actuation of device 1, contactor 4 moves to the closed position due to the actuation of actuator 5, and then source 3 supplies power to circuit 2 (specifically, electric bars 6 and 7). A short-circuit current then flows through the fusible wire 8, generating Joule losses within it, causing it to rapidly reach its melting point. When the molten fusible wire 8 breaks and disconnects, the short-circuit current is not interrupted instantaneously, and electrons passing through the medium (whether air or vacuum) between the two electric bars 6 and 7 ionize the medium, thereby initiating an arc that forms a conductive path between the two bars. The arc, sustained by source 3, only stops when contactor 4 disconnects.

[0019] However, applying this fusible wire technology to test or inspect electronic equipment (where the electronic equipment will be embedded, for example, mounted on an aircraft) presents several drawbacks and is difficult to conceive.

[0020] In practice, the electrical strips 6 and 7 of the arc-initiating device are, for example, two electrical traces on the electronic board of the device or two busbars of the electronic equipment under test, and are placed at different potentials when the device is energized. Therefore, arranging the fusible wire inside such equipment requires manual operation, i.e., disassembling the housing of the electronic equipment, for example laying and securing the fusible wire between the two electrical traces, and then reinstalling the housing. This complex manual operation has proven to be very delicate in practice, and its correct execution is crucial for the correctness and success of the test. In fact, if this operation is not performed correctly, for example, if the wire is not laid or secured correctly, the wire may be squeezed out before reaching its melting point under the electromotive force induced by the short-circuit current, and there will be no arc.

[0021] Furthermore, power electronic equipment (such as power converters, like inverters for motor control) or power supplies consist of power switches (especially bipolar transistors or field-effect transistors (MOSFETs, IGBTs, etc.) used as high-voltage switches) and power capacitors, which are typically used to filter the current connected to the high-voltage DC HDVC terminals required for the operation of such power equipment. These power capacitors present several challenges for proper testing.

[0022] Furthermore, tests using fusible wire technology have been observed to begin at zero voltage. The capacitors thus discharge. Because capacitors prevent large voltage changes at their terminals, they tend to maintain a voltage close to zero, which prevents arcing. Even if an arc were to form, it would not occur under realistic conditions. In practice, during operation, electronic equipment is energized, and these power capacitors are pre-charged. In the event of a short circuit, for example, by an arc, the energy stored in these power capacitors becomes a source of high discharge current in the equipment. In other words, during the operation of the equipment, these capacitors are charged and play an active role in short-circuit dynamics, which is masked by the fusible wire technology.

[0023] Existing alternatives include the drip method, which involves dripping ionized liquid onto exposed portions of a conductor or circuit, which dissolve under continuous dripping. However, this method is difficult to integrate into power electronic equipment, and its monitoring is unreliable. In particular, monitoring by solenoid valves is complex and expensive due to the risk of damage caused by the resulting electric arc. Summary of the Invention

[0024] One object of the present invention is to overcome the aforementioned disadvantages by providing a device for initiating an electric arc in electronic equipment, thereby testing the behavior of the electronic equipment under the action of the electric arc and / or under the action of an electrical fire generated by the electric arc. In particular, an object of the present invention is to provide a device that is reliable enough to easily initiate an electric arc under realistic conditions (i.e., under initial test conditions where the electronic equipment is already energized), suitable for power electronic equipment including power capacitors, and safe for the operator.

[0025] To this end, according to the first aspect, an apparatus is proposed for initiating an electric arc in electronic equipment to test the behavior of the electronic equipment under the action of the electric arc and / or under the action of an electrical fire generated by the electric arc. A power supply is provided to energize the equipment to establish a supply voltage between a first electrical trace or a first potential point and a second electrical trace or a second potential point of the equipment. The power supply is, for example, included in the initiating apparatus. The triggering equipment includes: A transistor, comprising a gate, a control pin, and two power pins, the two power pins being electrically connected such that one power pin is electrically connected to a first trace or a first potential point of the device, and the other power pin is electrically connected to a second trace or a second potential point of the device. The transistor is capable of withstanding a voltage greater than or equal to the supply voltage between its power pins, and the transistor is rated to allow a smaller current, approximately 5 to 15 times smaller than the current supplied by the power supply, to pass between the two power pins of the transistor. - A transistor control circuit, electrically isolated from the power supply and configured to apply a trigger control signal to a control pin, the trigger control signal being capable of causing the transistor to close irreversibly via an avalanche effect, while the device and thus a first trace or first potential point on one side and a second trace or second potential point on the other side are energized to generate an electric arc under the action of the current supplied by the power supply.

[0026] Advantageously, the power supply device for the initiating equipment includes a power supply and a power contactor, the power contactor being capable of: -Activated to the closed position so that the electronic device can be powered on before the trigger control signal is applied, the trigger control signal can cause the transistor to close and trigger an electric arc, and - It is activated to the disconnect position to de-energize the equipment, thereby cutting off the power supply to the arc.

[0027] Preferably, the electronic device includes at least one capacitor between the first electrical trace and the second electrical trace or between the first potential point and the second potential point, and the energization of the electronic device enables the capacitor to be charged.

[0028] Advantageously, the power supply device also includes a pre-charging circuit that is capable of limiting inrush current during the charging of the capacitor while the electronic equipment is powered on.

[0029] Advantageously, the control circuit for the transistor gate includes: A resistor divider bridge, comprising a high resistor and a low resistor, forms the output of a control circuit at the midpoint between the high and low resistors. The output of the control circuit provides the trigger control signal to the control pin of the transistor gate. as well as - A control contactor, connected in series with a resistor divider bridge, drives the resistor divider bridge to power in a closed state controlled by an activation signal, thereby establishing a trigger control signal that can cause the transistor to close irreversibly through the avalanche effect.

[0030] Advantageously, the resistor divider bridge of the control circuit is powered by a power supply.

[0031] Preferably, the control contactor and the resistor divider bridge are connected in series between a power contactor connected to the positive terminal of the power source on one side and the negative terminal of the source on the other side.

[0032] The present invention also relates to a method for inducing an electric arc on electronic equipment to test the behavior of the electronic equipment under the action of the electric arc and / or under the action of a fire generated by the electric arc, wherein the following steps are performed: - By electrically connecting one of the two power pins to the first electrical trace or first potential point (13a) of the device and electrically connecting the other of the two power pins to the second electrical trace or second potential point of the device, a transistor comprising two power pins and a gate control pin is arranged on the electronic device. - By energizing the power equipment and thus the first and second traces and / or the first and second potential points, a supply voltage is established between the power pins. - An arc is induced between the two power pins of a transistor by applying a control signal to the control pin of the transistor's gate. The control signal can cause the transistor to close via an avalanche effect, thus enabling the arc to be induced between the two power pins, through which current supplied by the power supply device is supplied.

[0033] Advantageously, energizing includes charging a capacitor, and the electronic equipment includes a capacitor between the first and second electrical traces or between the first and second potential points.

[0034] Advantageously, the capacitor is pre-charged during energization or pre-charged by a dedicated pre-charging device.

[0035] The present invention also relates to the use of the arc initiation device as defined above for testing the behavior of electronic equipment under the action of an electric arc and / or under the action of a fire generated by an electric arc, wherein the initiation method as defined above is applied to one or more samples of the electronic equipment whose behavior is to be tested.

[0036] Advantageously, electronic equipment is electrical equipment that is equipped with or intended to be equipped with an aircraft. Attached Figure Description

[0037] Other features, objects, and advantages of the present invention will become apparent from the following description, which is entirely illustrative and non-limiting and should be read in conjunction with the accompanying drawings, in which: Figure 1 An apparatus for initiating an electric arc under laboratory conditions, according to the prior art, is schematically shown; Figure 2 An apparatus for initiating an electric arc in electronic equipment according to the present invention and a first embodiment is schematically shown; Figure 3 The illustration shows the use of in Figure 2 Devices in electronic equipment that utilize possible embodiments of control circuitry to induce an electric arc; and Figure 4 The various steps of the method according to the invention are illustrated schematically.

[0038] In the accompanying drawings, similar elements are indicated by the same reference numerals. Detailed Implementation

[0039] Figure 2 A device 9 for testing electronic equipment 10 is shown, which is capable of ensuring that an electric arc is induced in said electronic equipment 10.

[0040] In the following text, the electronic equipment 10 under consideration is a power electronic equipment.

[0041] The electronic equipment 10 includes an electronic board 12 having various electronic components (in particular one or more power capacitors 14) and multiple electrical traces. Figure 2 A simplified diagram of a power capacitor 14 connected between two electrical traces 13a and 13b (i.e., in parallel between these two electrical traces 13a and 13b) is shown. These two electrical traces 13a and 13b are configured to distribute power to various components of the electronic device 10, and more specifically, to various components of the electronic board 12.

[0042] The initiating device 9 includes a power supply circuit 15 (or power supply device 15) and an initiating device 11, the initiating device including a transistor 19 and a circuit 20 for controlling the transistor 19.

[0043] Transistor 19 is a voltage-controlled field-effect transistor, such as a MOSFET or IGBT transistor. Transistor 19 includes a control pin 21 or gate, and two power pins (also called turn-on pins) 22a and 22b, which correspond to the drain and source pins of the MOSFET transistor, respectively, or the emitter and collector pins of the IGBT transistor, respectively. The following focuses on the case where transistor 19 is a MOSFET transistor.

[0044] Control pin 21 is controlled by control circuit 20.

[0045] The power supply circuit 15 includes a power supply 16 and a power contactor 17.

[0046] Power supply 16 supplies power to electronic board 12 via connection interface.

[0047] Current isolation and physical isolation are provided between the power supply 16 and the control circuit 20. This isolation is designed to ensure human safety.

[0048] The power supply 16 can be a DC voltage source; the power supply includes positive and negative terminals corresponding to positive voltage and negative voltage or zero voltage, respectively.

[0049] As previously described, the electronic board 12 includes a first electrical trace 13a and a second electrical trace 13b. The first trace 13a of the electronic board 12 is connected to the negative terminal of the power supply 16. The power contactor 17 is connected between the positive terminal of the power supply 16 and the second trace 13b of the electronic board 12, thus the second trace of the electronic board is connected to the positive terminal.

[0050] Power pin 22a (and correspondingly power pin 22b) is connected to first trace 13a (and correspondingly second trace 13b). Therefore, power pin 22a corresponds to the source of transistor 19 when transistor 19 is a MOSFET transistor, or to the collector of transistor 19 when transistor 19 is an IGBT transistor. Power pin 22b corresponds to the drain of transistor 19 when transistor 19 is a MOSFET transistor, or to the emitter of transistor 19 when transistor 19 is an IGBT transistor.

[0051] Alternatively, circuit board 12 may include potential points instead of traces 13a and 13b, which are set to high and low voltages respectively supplied by power supply 16 when equipment 10 and board 12 are powered on. Such potential points are, for example, busbars.

[0052] Within the electronic device 10, transistor 19 is arranged on the electronic board 12 in the region Z in which a test arc is to be induced. In the example shown, the region Z includes a power capacitor 14 arranged near traces 13a and 13b and connected to the traces 13a and 13b.

[0053] The specifications of power supply 16 are designed to provide a current known as the short-circuit current between its positive and negative terminals, corresponding to experimental conditions (e.g., 400 volts).

[0054] The power contactor 17 enables control of the energization of traces 13a and 13b, and thus controls the energization of the electronic board 12. When the contactor 17 is closed, the electronic board 12 is powered by the source 16, with the first trace 13a placed at a low voltage supplied by the negative terminal of the source 16 and the second trace 13b placed at a high voltage supplied by the positive terminal of the source 16.

[0055] The open or closed state of the power contactor 17 is controlled by the actuator 18. The actuator 18 may include a coil 18a, a power supply 18c, and a control device 18b, such as a switch arranged in series between the power supply 18c and the coil 18a. The power supply 18c has a first terminal and a second terminal, the first terminal being connected to the ground terminal of the actuator 18's circuit, and the second terminal being connected to the control device 18b.

[0056] When the control device 18b distributes energy generated by the power source 18c to the coil 18a, the coil 18a generates a magnetic field that causes the power contactor 17 to close, thereby powering the electronic board 12. Conversely, when the control device 18b does not distribute energy generated by the power source 18c to the coil 18a, the power contactor 17 remains or moves to the open position, thereby cutting off the power supply to the electronic board 12.

[0057] Preferably, the power supply circuit 15 further includes a circuit 17P for pre-charging the capacitor 14. This pre-charging circuit 17P provides protection against any electromagnetic interference that could damage the transistor 19 and thus induce an arc between the transistor's power pins 22a and 22b.

[0058] This allows for robust monitoring of the triggering conditions.

[0059] A pre-charge circuit 17P is connected in parallel to the power contactor 17, for example. This pre-charge circuit 17P typically includes, for example, current-limiting resistors and switches connected in series or parallel. When the power supply circuit 15 is energized, the pre-charge circuit enables the limitation of inrush current associated with the charging of the capacitor 14. Once the capacitor 14 is fully charged (which can be detected by tracking the current level), the power contactor 17 can be activated.

[0060] The control circuit 20 of transistor 19 includes a trigger control stage 20a, which provides a trigger control signal S20 applied to the gate 21 of transistor 19 at its output. The trigger control stage 20a includes the terminal of contactor 17 furthest from power supply 16 and the negative terminal of power supply 16 connected in series (corresponding to...). Figure 2 The following components are located between the positive voltage line 30b and the negative voltage line 30a: - Control contactor 25, and - High resistor 24 and low resistor 23 form a resistive voltage divider bridge 31 between positive voltage line 30b and negative voltage line 30a. The midpoint between the high and low resistors (i.e., the connection point between high resistor 24 and low resistor 23) provides the control signal S. 20 .

[0061] Therefore, the control contactor 25 is connected between the positive voltage line 30b and the high resistor 24. The low resistor 23 is connected between the high resistor 24 and the negative voltage line 30a.

[0062] The gate 21 of transistor 19 is connected to the midpoint of voltage divider bridge 31 via a connecting wire. Therefore, the midpoint of resistor divider bridge 31 defines the voltage output terminal S for controlling the gate of transistor 19. 20 .

[0063] In addition, the control circuit 20 includes an actuator 26, which is capable of receiving an activation signal E 20 The actuator 26 closes when the contactor 25 is activated. The actuator 26 may include a coil 26a, a power supply 26b for the coil 26a, and a control device 26c (e.g., a switch arranged in series between the power supply 26b and the coil 26a). This switch is switched from an open to a closed state, for example, by a test operator via a button. Closing this switch allows current to flow in the coil 26a, thereby triggering the closure of the contactor 25. The actuator 26 is electrically and physically isolated from the rest of the control circuitry 20 to ensure the safety of the operator activating or deactivating the actuator 26.

[0064] As long as the activation signal E20 is not emitted, the control contactor 25 is in an open state, isolating the high resistance 24 from the positive voltage line 30b. Therefore, the gate 21 of transistor 19 is anchored by the low resistance 23 of the voltage divider bridge 31, i.e., pulled to the potential of the negative voltage line 30a of the power supply 16. This enables the device 9 to be reinforced, preventing accidental startup during the power-on phase due to potential electromagnetic interference from the inherent stray capacitance level of transistor 19.

[0065] When the operator switches control device 26c to supply power to coil 26a, control contactor 25 is in a closed position that causes resistor divider bridge 31 to be energized.

[0066] The specifications of source 16 are determined based on electronic board 12 and desired test conditions. The specifications of low resistance 23 and high resistance 24 are determined accordingly. Resistors 23 and 24 of source 16 and voltage divider bridge 31 are selected such that the trigger control signal level S20 subsequently applied to control pin 21 of transistor 19 is significantly higher than the control level typically used to control transistor 19 in the on-state (closed-state). Therefore, this trigger control signal level S20 causes avalanche and irreversible closure of transistor 19. The irreversible nature of the closure prevents the effects of electromagnetic interference from wiring cables that could potentially disconnect transistor 19. This irreversible closure results in a short circuit of transistor 19 and an arc caused by its explosion.

[0067] In other words, the high resistance 24 of the resistor divider bridge 31 is designed to ensure that the gate control signal S... 20During the application step, the voltage d between the gate (control pin 21) and source (power pin 22a) of transistor 19 is significantly higher than the maximum gate-source voltage (denoted as Vgsmax) recommended by the manufacturer's specifications for the transistor 19 under consideration (specifically, a value 5 to 10 times higher) to ensure avalanche protection for transistor 19. Taking a MOSFET-type transistor 19 as an example, a MOSFET transistor suitable for power electronics applications can be selected, for instance, whose maximum gate-source voltage Vgsmax is between 20V and 30V (e.g., equal to 25V).

[0068] When a fault caused by an electric arc connects the control pin 21 to a low potential in the control circuit 20, the high resistance 24 also allows for limiting the current through the control contactor 25. When an electric arc occurs between traces 13b and 13a, a path to trace 13a is established (e.g., when the output of the control circuit 20, S...). 20 This fault is particularly likely to occur when the connection wire between the control pin 21 breaks and comes into contact with trace 13a. Therefore, this is referred to as fault propagation in the control circuit 20. In other words, the high resistance 24 limits the rated current of the control contactor 25.

[0069] Therefore, the high resistor 24 is designed to be connected in parallel with the power supply 16. In practice, an excessively high resistor 24 may limit control dynamics.

[0070] For example, in the case of a field-effect transistor (such as a MOSFET), the high resistance 24 ensures that its resistance does not exceed ten times the value of the equivalent drain-source resistance (typically denoted as Rdson) when the transistor 19 is in the on-state. This is a transistor characteristic value indicated by the manufacturer in the datasheet.

[0071] The control contactor 25 is designed to withstand the voltage applied by the power supply 16. The control contactor 25 is also designed to withstand the maximum current that can pass through the high resistor 24.

[0072] The low resistance 23 anchors the control pin 21 to a low potential of the negative voltage line 30a during the power-on phase of the device 10 (monitored by activation of the power contactor 17) until activated by the signal E. 20 Intentionally activate the trigger control. This low-potential setting allows any voltage at the midpoint of the resistive voltage divider bridge to be released during the power-on phase of device 10. This prevents any accidental initiation of an arc caused by device 9 after power-on.

[0073] The low resistance 23 has a value between 1 kiloohm and 10 kiloohms. Furthermore, the low resistance 23 is designed to be undamaged in the event that the control pin 21 of transistor 19 (and therefore the wire between the control circuit 20 and that pin 21) is accidentally placed under a positive voltage from the power supply circuit 15 during a fault propagation event as described above. In other words, the low resistance is designed to withstand certain voltage and current levels without damage.

[0074] The control signal S applied to control pin 21 20 The level of the signal causes irreversible closing of transistor 19, which results in transistor 19 heating up by the flow of the current required for testing and generated by power supply 16 in the semiconductor portion of transistor 19, between power pins 22a and 22b. In the following, the control signal S is triggered... 20 The current supplied by power supply 16 when applied to control pin 21 is called short-circuit current.

[0075] The heating caused transistor 19 and its housing 19a to explode, thus creating an electric arc between the two power pins 22a and 22b.

[0076] The explosion of transistor 19 triggers an electric arc, and the plasma of the arc forms and propagates between pins 22a and 22b, then between energized traces 13a and 13b. Therefore, traces 13a and 13b serve as arc electrodes. Thus, a power supply 16 connected to traces 13a and 13b provides energy to the arc.

[0077] At the end of the test, when the operator disconnects the control contactor 17 again, the connection between the power supply 16 and the traces 13a and 13b is broken, and the arc is no longer powered.

[0078] More specifically, the trigger control signal level S 20 This causes the voltage between control pin 21 and power pin 22b, which is connected to the positive terminal of power supply 16, to exceed the maximum gate-source voltage Vgsmax (a characteristic of transistor 19). This results in channel avalanche of transistor 19: transistor 19 irreversibly becomes on (closed). The process is similar for IGBT-type transistor 19: control signal S 20 This leads to avalanche of the channel of the MOSFET transistor that constitutes the input stage of the IGBT transistor 19.

[0079] Then, transistor 19 acts as a short-circuit circuit, causing all current supplied by power supply 16 (referred to as the short-circuit current rated by power supply 16) to flow between the power pins 22a and 22b of the transistor, resulting in extremely rapid heating and causing transistor 19 and its housing 19a to explode. This explosion breaks the electrical path between the two power pins 22a and 22b in the semiconductor portion of transistor 19. Since the flowing short-circuit current cannot be instantaneously interrupted by the explosion of housing 19a, electrons subsequently pass through the medium (whether air or vacuum) between the two power pins 22a and 22b and ionize the medium, resulting in an electric arc (initially retained between the power pins 22a and 22b of transistor 19), forming arc electrodes and generating plasma that can extend to traces 13a and 13b (the traces themselves subsequently become arc electrodes), and more generally, to the entire apparatus 10 under test. The arc thus initiated and sustained stops only when the power contactor 17 is disconnected (the power contactor cuts off the power supply). Regardless of the type of transistor 19 (MOSFET or IGBT), the triggering mechanism is similar.

[0080] Preferably, the trigger is performed when the power capacitor 14 has been pre-charged and the electronic device 10 and power pins 22a and 22b have been energized, in order to reproduce the actual operating conditions of the device 10 under test.

[0081] Therefore, the short-circuit sequence is triggered as follows: - By controlling the action of contactor 17 and power supply 16, the electronic equipment 10 under test (more specifically, electronic board 12) is powered on, including the charging of power capacitor 14 and the voltage biasing of power pins 22a and 22b of transistor 19. Then, power is supplied to the voltage divider bridge 31 via the action of the contactor 25 through the actuator 26, which is current-isolated from the rest of the control circuit 20, generating a trigger control S on the control pin 21 of the transistor 19. 20 .

[0082] The proposed arc initiation control offers several advantages. As will be understood, using the embodiment just described, the control contactor 17 must first be activated before the control stage 20a, which drives the control pin 21 of transistor 19, can be activated by the actuation of the control contactor 25. In this way, this prevents the unintentional application of an initiation control signal to the control pin 21 of transistor 19 before the start of the test (i.e., before the electronic board 12 is energized, especially before the power capacitor 14 is charged and before the power pins 22a and 22b of transistor 19 are biased).

[0083] The use of the control contactor 25, as described, allows for separation and electrical isolation between the test operator and the source 16, thereby ensuring human safety. Compared to conventional control circuits using transistor gates (referred to as the drive section), the control contactor 25, associated with the resistor divider bridge 31, constitutes a simple and robust control element.

[0084] The control circuit 20 described above contributes to the robustness of the arc control circuit; unlike conventional control circuits, this makes it possible to prevent unwanted interference (e.g., due to the discharge of capacitor 14 once it is charged), which in particular causes electromagnetic interference and can lead to the failure of the monitored arc to be initiated.

[0085] Specifically, the use of control contactor 25 and correctly sized resistors 23 and 24 ensures that the control circuit 20 will not be damaged due to any potential current propagation during the use of the initiating device 9. Therefore, the control circuit 20 is reliable and safe. Under the same experimental conditions, the control circuit can also be reused on another board equipped with new transistors 19. Finally, the initiation of the arc is very rapid, approximately a few microseconds to a millisecond, making the control circuit 20 insensitive to the bounce of control contactor 25. In practice, those skilled in the art select the high and low resistances of the voltage divider bridge 31 based on the type and technical characteristics of the selected transistor 19 and the experimental conditions (short-circuit voltage and current).

[0086] As previously described, device 9 may advantageously include circuitry 17P for pre-charging power capacitor 14 to limit inrush current. This limits electromagnetic interference in downstream electronics and avoids the risk of unwanted arcing.

[0087] Transistor 19 is sized to withstand a voltage between its power pins 22a and 22b equal to or greater than the voltage supplied by source 16 between traces 13a and 13b. Therefore, transistor 19 is sized to prevent failure, specifically to prevent short circuits solely due to the energization of traces 13a and 13b, thus preventing the risk of accidental short circuits triggered at transistor 19.

[0088] Transistor 19 was also selected to have a rated current that is at least ten times lower than the target short-circuit current in the experiment, thereby ensuring the heating conditions for initiating an electric arc.

[0089] Furthermore, transistor 19 typically includes a semiconductor chip encapsulated within a housing 19a. Preferably, housing 19a is a dry housing, meaning it contains no substances or gels that could interfere with the initiation of the arc. For example, housing 19a is a TO220 or TO247 type housing. The size of the housing will be selected based on experimental conditions to ensure a sufficiently rapid explosion conducive to arc initiation while generating sufficient contamination to ensure arc development.

[0090] As a variant, such as Figure 3 As shown (elements shared with previous embodiments have the same reference numerals), control circuit 20 includes its dedicated power supply 27, such as an auxiliary power source, like a battery. Therefore, control circuit 20 is electrically independent of power supply 16. As previously stated, actuator 26 does not share a common electrical reference point with control circuit 20 to ensure current and physical isolation for operator safety. In this embodiment, power supply 27 applies a positive voltage to one terminal of control contactor 25 opposite to resistor divider bridge 31, and a negative voltage or zero voltage to one terminal of resistor divider bridge 31 opposite to control contactor 25. This voltage must be high enough that a control signal applied to control pin 21 of transistor 19 causes transistor 19 to eventually close, as shown in the reference... Figure 2 As described in the embodiment shown. In this alternative embodiment, the power pins 22a and 22b of transistor 19 are kept biased by power supply 16, which provides the short-circuit current required to initiate an arc, to heat transistor 19 and cause it to explode when fully closed.

[0091] Furthermore, in this embodiment, the pre-charge circuit 17P is also necessary, especially when the power capacitor 14 is a high-value capacitor (e.g., several hundred microfarads).

[0092] Figure 4 Different steps of a method for inducing an electric arc in electronic equipment (e.g., electronic equipment 10) are shown.

[0093] In the first step E1, the parameters of the trigger circuit are selected to correspond to the test to be performed. More specifically, the transistor 19 and resistors 23 and 24 are selected based on the voltage applied between the pins of the transistor by source 16 and the target short-circuit current of the experiment: typically, the selection will focus on the properties of transistor 19 (MOSFET, IGBT), the transistor's case type 19a, and the transistor's electrical characteristics, particularly the current and voltage ratings specified by the manufacturer, i.e., the maximum current the transistor can conduct (in normal operating mode) and the maximum voltage that can be applied between the transistor's power pins. For MOSFET transistors, these characteristics are expressed as Idsmax and Vdsmax.

[0094] Specifically, transistor 19 is configured to prevent it from interfering with the operation of device 10, provided that it does not trigger the initiation of an electric arc. More specifically, transistor 19 is configured to withstand the voltage applied between traces 13a and 13b by power supply 16.

[0095] In addition, to ensure the initiation of the arc, transistor 19 is selected such that the transistor's rated current (or current rating) is at least ten times lower than the target short-circuit current of the experiment provided by power supply 16 (or, if applicable, by a specific power supply 27 of the control circuit).

[0096] Furthermore, the choice of the transistor's housing 19a must be related to the conditions required for the initiation of the arc. In particular, the housing cannot be too large so that it will take too long to explode, nor too small so that it will not generate sufficient contamination during the explosion to ensure the proper development of the arc.

[0097] For example, for arc testing targeting a direct supply voltage of 540VDC and a short-circuit current of 400A, a MOSFET transistor with a Vdsmax value of 600V, an Idsmax value of 15A, and a Vgsmax value of 25V and a TO220 housing are selected.

[0098] The specifications of resistors 23 and 24 in control circuit 20 are determined based on the selected transistor 19, specifically such that the values ​​of the gate 21 and source 22a voltages of transistor 19 are between 5 and 10 times greater than the maximum gate-source voltage Vgsmax specified by the transistor manufacturer for transistor 19. The high resistor 24 is also designed to not exceed ten times the equivalent drain 22b and source 22a resistances of transistor 19 (denoted as Rdson, indicated by the manufacturer of transistor 19) when the transistor is in the on-state. The low resistor 23 has a value between 1 kiloohm and 10 kiloohms. The control contactor 25 is specified to withstand the voltage applied by source 16 and also the maximum current that can pass through the high resistor 24.

[0099] As described above, an example of a power supply device using a MOSFET transistor 19 with a TO220 housing, voltage and current ratings of 600V and 15A, and specifications designed to provide a DC voltage of 540VDC and a short-circuit current of 400A, could be, for example: - For low resistance 23, select a 1 kΩ resistor that can withstand at least 600V and 300W of power during the use of device 9; - For the high resistance 24, choose a resistor of 150 kΩ, which roughly corresponds to the apparent resistance of this transistor 19 when it is in the on state (usually expressed as R). DSON Ten times that of ).

[0100] The voltage at the midpoint of the voltage divider bridge 31, obtained by this high resistance 24 and low resistance 23, is 470 volts, while the Vgsmax value of the transistor in question is 25 volts, which ensures good avalanche in the channel of transistor 19.

[0101] In this example, the current and voltage ratings of the control contactor 25 will be configured to withstand at least 600V and 4A.

[0102] In step E2, the arc-initiating device 9 is mounted on the electronic equipment 10. More specifically, the transistor 19 of the initiating device 11 is arranged on the electronic equipment 10 by fixing two power pins 22a and 22b to two traces or two potential points 13a and 13b of the electronic equipment 10.

[0103] The pins 22a and 22b of the transistor 19 initiating the device are secured, for example, by soldering to traces 13a and 13b. This allows for robust mechanical mounting and good electrical connection. This eliminates the risk of the transistor popping out (detaching from the board), for example, due to the electrodynamic force generated by the initiation of an arc between power pins 22a and 22b. Of course, other mounting methods are conceivable.

[0104] In the third step E3, the power electronic device 10 is energized by the power supply circuit 15 through the closed power contactor 17. The control contactor 25 is in the open position of the control circuit 20, and the control pin 21 is not energized. Preferably, a circuit 17P for pre-charging the capacitor 14 is provided to limit inrush current, and this circuit is activated before the power contactor 17. During the pre-charging and energizing steps of the board 12 / device 10, the control circuit 20 is not activated. The control pin 21 of the transistor 19 is pulled to the potential of the negative voltage line 30a by the low resistance 23 of the resistor divider bridge 31 of the control circuit 20.

[0105] Following this third step E3, an activation signal E is applied to the input terminal of the control circuit 20. 20 The generation of this causes the control contactor 25 to close, thus triggering the fourth stage E4. In this fourth step E4, the control circuit 20 applies a trigger control signal S to the control pin 21. 20 This causes transistor 19 to close, allowing short-circuit current to flow and thus initiating an electric arc. Consequently, power contactor 17 and control contactor 25 are in the closed position.

[0106] Suitable instruments (visualization systems such as high-speed cameras, current and voltage measuring devices at various points on electronic equipment, etc.) enable the tracking of the behavior of electronic equipment under the influence of an electric arc and, if applicable, under the influence of fire generated by the electric arc.

[0107] The initiating device and the sample to be tested are arranged, for example, in a protective enclosure for testing. This enclosure may also be equipped with a smoke extraction system.

[0108] Multiple samples of the same equipment can be tested under different supply voltages. These can also vary depending on the equipment being tested.

[0109] Furthermore, in the final step E5, the power contactor 17 is disconnected. This will cut off the arc if the experiment does not stop prematurely during testing due to damage to the equipment itself. This also allows the operator to safely access the enclosure to remove the equipment and, if necessary, conduct further observation of the equipment.

[0110] In this specification, the electronic device 10 considered is a power electronic device. The invention is not limited to this embodiment and is applicable to any other type of electronic device. In other words, the specifications of the control circuit 20 and the transistor 19 are designed to match the supply voltage level of the electronic device 10 considered and the target short-circuit current level of the experiment.

Claims

1. An apparatus (9) for initiating an electric arc in electronic equipment (10) to test the behavior of the electronic equipment under the action of the electric arc and / or under the action of an electrical fire generated by the electric arc, wherein a power supply device (15) is provided to energize the equipment to establish a supply voltage between a first electrical trace or a first potential point and a second electrical trace or a second potential point (13a, 13b) of the equipment, the initiating apparatus (9) comprising: - Transistor (19), the transistor comprising a control pin (21) and two power pins (22a, 22b) of the transistor gate, the two power pins (22a, 22b) being electrically connected such that one power pin is electrically connected to a first electrical trace or a first potential point of the device, and the other power pin is electrically connected to a second electrical trace or a second potential point (13a, 13b) of the device (10), the transistor being able to withstand a voltage greater than or equal to the supply voltage between its power pins, and the transistor being rated to allow a smaller current, approximately 5 to 15 times smaller than the current supplied by the power supply device (15), to pass between the two power pins (22a, 22b) of the transistor. - A transistor control circuit (20), which is electrically isolated from the power supply device (15) and configured to apply a trigger control signal (S) to the control pin (21). 20 The triggering control signal can cause the transistor (19) to close irreversibly through the avalanche effect, while the equipment and thus the first trace or first potential point (13a) on one side and the second trace or second potential point (13b) on the other side are energized to generate an electric arc under the action of the current supplied by the power supply device (15).

2. The device (9) according to claim 1, wherein, The power supply device (15) of the initiating device (9) includes a power supply (16) and a power contactor (17), the power contactor being capable of: - is activated to the closed position so that when the trigger control signal (S) is applied... 20 The previously mentioned electronic equipment (10) is energized, and the triggering control signal can cause the transistor (19) to close and trigger an electric arc, and - It is activated to the disconnect position to de-energize the equipment, thereby subsequently cutting off the power supply to the electric arc.

3. The device according to claim 2, wherein, The electronic device (10) includes at least one capacitor (14) between the first electrical trace and the second electrical trace (13a, 13b) or between the first potential point and the second potential point, and the energization of the electronic device (10) enables the capacitor (14) to be charged.

4. The device (9) according to claim 3, wherein, The power supply device (15) also includes a pre-charging circuit (17P) that is capable of limiting inrush current during the charging of the capacitor (14) while the electronic equipment (10) is powered on.

5. The device (9) according to any one of claims 1 to 4, wherein, The control circuit (20) for the gate of the transistor includes: - A resistor divider bridge (31), the resistor divider bridge including a high resistor (24) and a low resistor (23), the midpoint between the high resistor (24) and the low resistor (23) of the resistor divider bridge forms the output terminal of the control circuit (20), the output terminal of the control circuit provides the trigger control signal (S) on the control pin (21) of the gate of the transistor (19). 20 ),as well as - Control contactor (25), which is connected in series with the resistor divider bridge (31) to respond to the activation signal (E) 20 In the closed state controlled by the control, the resistor divider bridge is energized, thereby establishing a trigger control signal (S) that can cause the transistor (19) to close irreversibly through the avalanche effect. 20 ).

6. The device (9) according to claim 5 in combination with claim 2, wherein, The resistor divider bridge (31) of the control circuit (20) is powered by the power supply (16).

7. The device (9) according to claim 6, wherein, The control contactor (25) and the resistor divider bridge (31) are connected in series between the power contactor (17) connected to the positive terminal of the power source (16) on one side and the negative terminal of the source (16) on the other side.

8. A method for testing the behavior of electronic equipment (10) under the action of the arc and / or under the action of a fire generated by the arc by initiating an arc on electronic equipment (10) using an arc initiating device (9) according to any one of claims 1 to 7, wherein, Implement the following steps: - By electrically connecting one of the two power pins (22a, 22b) of the transistor (19) to the first electrical trace or first potential point (13a) of the device (10) and electrically connecting the other power pin (22a, 22b) of the transistor (19) to the second electrical trace or second potential point (13b) of the device (10), the transistor (19) of the arc initiating device (9) is arranged (E2) on the electronic device (10). - The electronic equipment (10) is energized (E3) by the power supply device (15) and thus the first and second traces and / or the first and second potential points (13a, 13b) are energized to establish a supply voltage between the power pins (22a, 22b). - An arc (E4) is induced between the two power pins (22a, 22b) of the transistor (19) by applying a control signal (S20) to the control pin (21) of the gate of the transistor (19) by the control circuit of the arc initiation device (9), the control signal being capable of causing the transistor (19) to close irreversibly by avalanche effect, so that an arc can be induced between the two power pins, and the current supplied by the power supply device (15) of the equipment flows through the two power pins.

9. The method according to claim 8, wherein, The power supply (E3) includes charging the capacitor (14), and the electronic device (10) includes the capacitor between the first electrical trace and the second electrical trace (13a, 13b) or between the first potential point and the second potential point.

10. The method according to claim 9, wherein, The capacitor (14) is precharged during power-on or precharged by a dedicated precharge device (17P).

11. The use of the arc-initiating device (9) according to any one of claims 1 to 7 for testing the behavior of electronic equipment (10) under the action of an electric arc and / or under the action of a fire generated by an electric arc, wherein, The triggering method according to any one of claims 8 to 10 is applied to at least one electronic device (10) whose behavior is to be tested.

12. The use according to claim 11, wherein, The electronic equipment (10) is electrical equipment that is equipped on or intended to be equipped on an aircraft.

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