System for protecting an electrical circuit of a motor vehicle

Abstract

The invention relates to a system for protecting an electrical circuit, which system comprises: - a main pyrotechnic circuit breaker (1) comprising: • a main electrical conductor (100); • a main electro-pyrotechnic initiator (10) arranged to cause the main electrical conductor (100) to be cut off; - a device (2) for disconnecting the electrical circuit, which device comprises: • a fuse element (21); • a priming circuit breaker (20) comprising:  a priming conductor (200);  a pyrotechnic priming actuator (201) arranged to be controlled by an electronic control unit so as to cut off the priming conductor (200), characterised in that a cut-off voltage of the priming circuit breaker (20) and / or a cut-off voltage of the fuse element (21) are each lower than a supply voltage of the electrical circuit, and in that the main electro-pyrotechnic initiator (10) is connected to the disconnection device (2) in order to be triggered by the disconnection device (2).

Description

DESCRIPTION TITLE: PROTECTION SYSTEM FOR AN ELECTRICAL CIRCUIT IN A MOTOR VEHICLE Technical field of the invention

[0001] The present invention relates generally to electrical circuit protection systems, and more particularly to circuit breakers for electrical circuits in motor vehicles. State of the art

[0002] It is known in the prior art of electrical circuit protection systems, as in document WO201742321 or document US20200279711. Documented protection systems for electrical circuits often incorporate active and / or passive safety solutions. Active protection typically involves electronic monitoring and control systems capable of detecting and responding quickly to faults or abnormal operating conditions. Passive protection, on the other hand, relies on components such as fuses and circuit breakers that automatically interrupt the electrical circuit when certain voltage or current thresholds are exceeded. Meanwhile, high-voltage electrical circuits are widely used in various applications, particularly in electric and hybrid vehicles.With the increasing adoption of these vehicles, ensuring the safety and reliability of high-voltage electrical circuits has become increasingly important. Conversely, the protection systems referenced above may have drawbacks related to the speed at which the electrical circuit is interrupted, particularly during a passive circuit interruption, i.e., without intervention from an electronic control unit. Furthermore, these protection systems may not be suitable for high voltages present at the terminals of the electrical circuit. In particular, the use of fuses designed to interrupt circuits subjected to high voltages (greater than one or (several hundred volts) can be a drawback in ensuring performance throughout the vehicle's lifespan (typically around fifteen years). This is because fuses designed to interrupt circuits subjected to high voltages can experience accelerated aging. Description of the invention

[0003] One object of the present invention is to address the drawbacks of the prior art mentioned above and in particular, firstly, to provide an electrical circuit protection system suitable for an electrical circuit supplied under high voltage, and / or arranged to effectively interrupt the electrical circuit with or without intervention from an electronic control unit (in other words, a device arranged to operate both autonomously and actively), and / or capable of guaranteeing satisfactory operating performance throughout the life of a motor vehicle and / or arranged to be as simple as possible, and / or to offer a better compromise between these constraints than known systems.

[0004] To this end, a first aspect of the invention may relate to a system for protecting an electrical circuit, comprising: - a main pyrotechnic circuit breaker comprising: • a main electrical conductor arranged to be connected to the electrical circuit, • a main electro-pyrotechnic igniter arranged to be triggered and cause the main electrical conductor to break, - an electrical circuit disconnection device comprising: • a first terminal and a second terminal, • a fusible element, preferably connected to the main electrical conductor, and one terminal of which corresponds to one of the first and second terminals of the disconnecting device, • a starting circuit breaker comprising: ■ a starting conductor, preferably connected to the main electrical conductor, and one terminal of which corresponds to the other of the first and second terminals of the disconnecting device, ■ a pyrotechnic initiation actuator arranged to be controlled by an electronic control unit so as to cut the initiation conductor, characterized in that a breaking voltage of the initiation circuit breaker and / or a breaking voltage of the fusible element are each less than a supply voltage of the electrical circuit, and in that the main electro-pyrotechnic igniter is connected on one side to the first terminal of the disconnecting device and on the other side to the second terminal of the disconnecting device to be triggered by the disconnecting device.

[0005] The breaking voltage (or rating voltage) of a conductor interrupting element in an electrical circuit, such as a fuse, circuit breaker, or fuse, is the maximum voltage applied across its terminals beyond which the interrupting element cannot stop the flow of current when the conductor has been severed or destroyed. According to this implementation, breaking voltages of the fuse and fuse that are lower than, and preferably strictly lower than, the supply voltage of the electrical circuit cannot allow the interruption of the flow of electric current in the electrical circuit when the initiating conductor has been severed or destroyed due to a high-voltage supply to the electrical circuit. Thus, the fuse and fuse are rated to interrupt current in the initiating conductor at low supply voltages. (typically less than 100 V), and cannot prevent the flow of electric current in the starting conductor in the form of at least one electric arc between the terminals of the disconnecting device for high supply voltages (typically greater than one or several hundred volts).

[0006] The main pyrotechnic circuit breaker can be triggered by the formation of an electric arc between the terminals of the fusible element or between two severed ends of the initiating conductor by the initiating circuit breaker. The severing of the electrical circuit, and the resulting electric arc, can be created on command when the initiating circuit breaker is activated. The initiating circuit breaker contributes to the active interruption or opening of the electrical circuit. The electric arc can also form when the fusible element (which may be, for example, a fuse or a thermal fuse) melts if the fusible element carries an electric current exceeding a certain rating. The fusible element contributes to the passive interruption of the electrical circuit.An electrical circuit protection system according to the present invention therefore has the advantage of being controllable both actively and passively. It should also be noted that the described configuration allows for active or passive interruption of the high-voltage circuit at a lower cost, while maintaining isolation or at least separation between the high-voltage circuit and the typically low-voltage control circuit (with, in particular, an electronic control unit that can be damaged by high-voltage currents, and which, in the described configuration, is not directly connected to the high-voltage circuit breaker).

[0007] The controlled firing of the pyrotechnic initiation actuator with reduced cutoff voltage reduces the cost and simplifies the dual (active / passive) firing function of the main electrical circuit breaker. Indeed, the pyrotechnic initiation actuator is simpler, more compact and less expensive than the main electrical circuit breaker; the invention is simpler and more modular than the prior art and makes it possible to offer the dual function (active / passive cutting of a high voltage circuit) from existing components that can be integrated into other protection systems.

[0008] The main electro-pyrotechnic igniter is connected to the terminals of the disconnecting device. In other words, the main electro-pyrotechnic igniter and the disconnecting device are connected in parallel. Before the disconnecting device is triggered, its electrical resistance is zero or nearly zero, and only a very small leakage current flows through the main electro-pyrotechnic igniter (which itself has a non-negligible internal resistance). After the disconnecting device is triggered, a potential difference (caused by the formation of an electric arc) across the disconnecting device causes an influx of electric current (i.e., an increase in current intensity) across the main electro-pyrotechnic igniter. The main electro-pyrotechnic igniter is then triggered and contributes to disconnecting the main electrical conductor.The main pyrotechnic circuit breaker does not require external control, for example from an electronic control unit, which provides space and energy savings compared to the use of a conventional pyrotechnic circuit breaker.

[0009] When the main electro-pyrotechnic igniter is triggered, the main pyrotechnic circuit breaker disconnects the main electrical conductor. The breaking voltage of the main pyrotechnic circuit breaker is higher than the supply voltage of the electrical circuit. Thus, the main pyrotechnic circuit breaker interrupts the flow of electric current even at high supply voltages in the main electrical conductor, notwithstanding the electric arc in the disconnecting device. Regardless of the passive or active switching method used in the disconnecting device to interrupt the electric current and / or open the electrical circuit, the main electrical conductor is severed by the main pyrotechnic circuit breaker, ensuring a fast and reliable interruption of the electric current in the high-voltage powered electrical circuit.

[0010] Finally, it can be noted that the fusible element (a fuse or a thermal fuse) being sized for low voltages, the fusible element has a so-called low voltage cut-off voltage, and therefore a better resistance to aging than a fusible element which would have a so-called high voltage cut-off voltage, higher than the voltage of the electrical circuit.

[0011] The electrical circuit protection system can be defined by the following characteristics, taken individually or in combination.

[0012] According to one embodiment, the fusible element may have a predetermined current threshold value beyond which it melts or breaks its internal conductor.

[0013] In one embodiment, the fusible element may be connected in series with the initiation conductor of the initiation circuit breaker or may be connected between two separate parts of the initiation conductor, and / or the fusible element may form at least part of the initiation conductor of the initiation circuit breaker. In a particular embodiment, when the initiation conductor forms at least part of the fusible element, the initiation circuit breaker may be arranged to destroy or interrupt the fusible element. Interrupting the fusible element is easier than interrupting the initiation conductor; thus, the sizing of the pyrotechnic initiation actuator can be optimized in terms of power and size. When the initiation conductor forms the fusible element, the initiation conductor may be the fusible element along its entire length within the initiation circuit breaker, and When the initiating conductor is formed by only a portion of the fusible element, only a portion of the initiating conductor within the circuit breaker can be formed by the fusible element, and the fusible element is then connected in series with the initiating conductor or between two separate sections of the initiating conductor. Integrating the fusible element into the initiating circuit breaker results in a more compact and efficient design, reducing the overall size and complexity of the protection system.

[0014] In one embodiment, the initiating circuit breaker may comprise a single cutting blade and / or may not generate an electrically free strand when the initiating conductor is broken. Its breaking voltage may therefore be lower than a high supply voltage of the electrical circuit. After the break, the initiating conductor comprises two distinct ends extending from the section. Under the effect of the high supply voltage and / or the short distance between the ends of the initiating conductor, an electric arc is formed between the ends of the initiating conductor, and electric current continues to flow in the initiating conductor.

[0015] In one embodiment, a resistive element may be connected in series with the main electro-pyrotechnic igniter and with either the first or second terminal of the disconnecting device. The resistive element has a resistance value between 20 and 100 ohms, and preferably between 50 and 100 ohms, approximately 80 ohms. The resistance value of the fusible element is lower than the resistance value of the resistive element, and preferably much lower. Thus, when an electric current below the predetermined threshold value flows in the electrical circuit, the current passes mainly or almost exclusively through the igniter and the fusible element, which have an equivalent resistance lower than the equivalent resistance of the main electro-pyrotechnic igniter in series with the resistive element.It can then be considered that the fusible element and the initiating conductor are connected. in series with the main pyrotechnic circuit breaker. However, in the event that a current intensity exceeding the predetermined threshold value produces an electric arc in the disconnecting device, an arc voltage can be measured across the terminals of the disconnecting device, which is sufficient to trigger the main electro-pyrotechnic igniter connected in parallel with the disconnecting device.

[0016] According to one embodiment, the supply voltage of the electrical circuit can be between 100 V and 5000 V, preferably between 200 V and 4000 V, preferably between 250 V and 2500 V.

[0017] In one embodiment, the breaking voltage of the initiating circuit breaker and the breaking voltage of the fusible element may each be less than 200 V, preferably less than 100 V, preferably less than 80 V, preferably less than 50 V, and / or in which the breaking voltage of the initiating circuit breaker and the breaking voltage of the fusible element are each less than two, preferably five, preferably ten times the supply voltage. Thus, the disconnecting device alone is incapable of interrupting the current in the electrical circuit to be protected. However, the aging resistance of the fusible element is better than that of a high-voltage fusible element. The costs of the disconnecting device are lower with a low-voltage fusible element.

[0018] In one embodiment, the breaking voltage of the main pyrotechnic circuit breaker may exceed 1000 V, and preferably 1500 V, and / or the breaking voltage of the main pyrotechnic circuit breaker may exceed 1.5 times, preferably 2 times, and preferably 2.5 times the supply voltage. Thus, the main pyrotechnic circuit breaker is designed to be able to interrupt the current in the electrical circuit to be protected by itself.

[0019] According to one embodiment, the main pyrotechnic circuit breaker can be arranged to cut at least one free strand of the The main electrical conductor is cut during the interruption of the main electrical conductor, and preferably at least two free strands are present. The formation of free strands ensures the complete severance of the main electrical conductor and the interruption of the current in the main electrical conductor. Indeed, the arc length and arc voltage in the main pyrotechnic circuit breaker are greater than those present in the initiating circuit breaker, thus guaranteeing the interruption of a high-voltage electrical circuit.

[0020] In one embodiment, the main pyrotechnic circuit breaker and the disconnecting device may be separate devices, and / or the main electro-pyrotechnic igniter and the pyrotechnic priming actuator may be separate devices. Design modularity is improved.

[0021] In one embodiment, the protection system may include an electronic control unit that can be arranged to trigger the pyrotechnic initiation actuator. This configuration allows for active control and monitoring of the protection system, enabling a rapid response to detected faults or hazardous conditions, even in advance or in the absence of excessive current for the electrical circuit.

[0022] In one embodiment, the protection system includes a transient voltage suppression diode connected in series with the resistive element and with either of the first or second terminals of the disconnecting device. In embodiments or in use cases where the voltage between the first and second terminals of the disconnecting device is low or zero, for example, less than 90 V or 100 V, and where the conductor has been interrupted by the disconnecting device: - an electric arc can form in the ignition circuit breaker and be capable of causing the diversion and passage of current towards the main circuit breaker, but whose intensity is less than a tripping threshold of the main circuit breaker; - if the voltage between the first and second terminals of the disconnecting device is zero, no electric arc will appear when the starting conductor is cut; the current will be entirely directed towards the main circuit breaker without reaching the tripping threshold of the main circuit breaker. In specific cases where current is directed towards the main circuit breaker without reaching its tripping threshold, the transient voltage suppression diode allows the current flow through the main circuit breaker to be completely blocked or at least significantly reduced, only allowing the significant current to flow above a certain voltage threshold across its terminals (with a positive and a negative voltage threshold). The electrical current can therefore be blocked and the circuit isolated even more effectively with a low supply voltage. Alternatively, a Zener diode can also be used instead of a transient voltage suppression diode.

[0023] A second aspect of the invention may relate to a motor vehicle comprising: - an electrical circuit protection system according to the first aspect of the invention, - an electrical circuit with a traction battery and / or a traction motor, - the electronic control unit arranged to control the firing of the priming circuit breaker.

[0024] A third aspect of the invention relates to a method for protecting a high-voltage electrical circuit, comprising: - the supply of a main pyrotechnic circuit breaker comprising: • a main electrical conductor arranged to be connected to the electrical circuit, • a main electro-pyrotechnic igniter arranged to be triggered and cause the main electrical conductor to be interrupted; - the supply of an electrical circuit disconnection device comprising: • a first terminal and a second terminal, • a fusible element, one terminal of which corresponds to one of the first and second terminals of the disconnecting device, • a starting circuit breaker comprising: ■ a starting conductor, one terminal of which corresponds to the other of the first and second terminals of the disconnecting device, ■ a pyrotechnic initiation actuator arranged to be controlled by an electronic control unit so as to cut the initiation conductor, wherein a breaking voltage of the initiation circuit breaker and / or a breaking voltage of the fusible element are each less than a supply voltage of the electrical circuit; - the connection of one of the two terminals of the main conductor of the main pyrotechnic circuit breaker with a terminal of the disconnecting device; - the connection of the other terminal of the main conductor of the main pyrotechnic circuit breaker with the electrical circuit; - the connection of the igniter of the main pyrotechnic circuit breaker in parallel with the disconnecting device; - the generation of an electric arc in the disconnecting device, of so as to create a voltage across the terminals of the disconnecting device; and - a triggering of the main pyrotechnic circuit breaker.

[0025] In other words, the third aspect relates to the use of a protective device, including: - the installation of the connection device in the electrical circuit to be protected, - the generation of an electric arc in the disconnecting device which induces the generation of a voltage exceeding a tripping voltage across the terminals of the disconnecting device, - the triggering of the main electro-pyrotechnic igniter of the main circuit breaker.

[0026] According to one aspect, a method for the preventive protection of a high-voltage electrical circuit can be envisaged, comprising the steps of: - to equip an electrical circuit protection system according to the first aspect, - to trigger the initial circuit breaker, preferably when the electrical circuit to be protected is not powered and / or not energized, and / or powered at a voltage or with a current insufficient to trigger the main circuit breaker, - to diagnose the tripping of the main circuit breaker and / or to perform a current flow test through the protection system of an electrical circuit.

[0027] If the ignition cut-off switch has been tripped, for example, to provide preventative protection, while no current was flowing in the electrical circuit, no electric arc is generated and the main electro-pyrotechnic igniter will not be triggered. Consequently, a small current may still flow through the protection system, and this can be verified by passing a test current. Therefore, the method may involve attempting to pass a test current (typically less than or equal to the no-fire current of the main electro-pyrotechnic igniter) to verify if the cut-off switch is functioning correctly. The main pyrotechnic igniter may or may not have been activated. Therefore, a diagnostic can be performed to determine if only the ignition cut-off switch (which is by definition less expensive than the main cut-off switch) needs replacing after such a preventive protection activation. It is also possible to measure or test the resistance of the main electro-pyrotechnic igniter and / or the resistance of the protection system, comparing this resistance with the expected resistance when the main electro-pyrotechnic igniter has not been triggered. Description of the figures

[0028] Other features and advantages of the present invention will become more apparent upon reading the following detailed description of embodiment(s) of the invention given by way of non-limiting example(s) and illustrated by the accompanying drawings, in which:

[0029] [fig. 1] represents a diagram of an electrical circuit protection system according to the invention comprising a main pyrotechnic circuit breaker and a disconnecting device with an initiation circuit breaker;

[0030] [fig. 2] represents a cross-sectional view of the priming circuit breaker of the disconnecting device of figure 1;

[0031] [fig. 3] represents a cross-sectional view of the main pyrotechnic circuit breaker of figure 1.

[0032] Detailed description of implementation method(s)

[0033] Figure 1 represents an electrical circuit protection system according to the invention comprising: - a main pyrotechnic circuit breaker 1, - a device for disconnecting electrical circuit 2, - a resistive element 11.

[0034] The main pyrotechnic circuit breaker 1 is arranged to interrupt a main electrical conductor 100 connected in series with the rest of the electrical circuit to be protected (including, in particular, a generator of voltage, such as a traction battery and / or a traction motor of a motor vehicle).

[0035] The main pyrotechnic circuit breaker 1 is arranged to interrupt the electrical current throughout the electrical circuit when the voltage generator produces a high voltage (e.g., greater than 100 V, or greater than 500 V) across the terminals of the electrical circuit. The main pyrotechnic circuit breaker 1 includes a main electro-pyrotechnic igniter 10 arranged to trigger the interruption of the main electrical conductor 100, typically by means of a cutting piston, as will be explained with reference to Figure 3. The main electro-pyrotechnic igniter 10 is connected in parallel with the disconnecting device 2; that is, one of its terminals is connected to one terminal of the disconnecting device 2 and the other of its terminals is connected to the other terminal of the disconnecting device 2. Thus, the main electro-pyrotechnic igniter 10 triggers the interruption only if it receives a current interruption signal from the disconnecting device 2.

[0036] The resistive element 11 is connected in series with the main electro-pyrotechnic igniter 10 and the corresponding terminal of the disconnecting device 2. The resistive element 11 can be arranged between the disconnecting device 2 and any pin of the main electro-pyrotechnic igniter 10. The resistance of the resistive element 11 is fixed and is preferably approximately 80 ohms. The resistance of the resistive element 11 is adjusted according to the sensitivity of the main electro-pyrotechnic igniter 10 and the voltage generated by the voltage generator so that any interruption of the electrical circuit supplied by the disconnecting device 2 results in a sufficient current increase to ignite or trigger the main electro-pyrotechnic igniter 10.It is also possible to plan to choose the main electro-pyrotechnic igniter 10 (in particular its ignition current) taking into account the resistance of the resistive element 11 and the voltage generated by the voltage generator.

[0037] The disconnecting device 2 comprises a fusible element 21 and a priming circuit breaker 20 connected in series. The priming circuit breaker 20 comprises a priming conductor 200 to one terminal of which the fusible element 21 can be connected, and a pyrotechnic priming actuator 201. The priming conductor 200 is arranged to be interrupted by the priming circuit breaker 20 when an external priming signal received by the priming circuit breaker 20 commands the firing of the pyrotechnic actuator 201. The external priming signal can be sent by an electronic control unit (ECU). The fusible element 21 can be integrated into the starting conductor 200, i.e. form a portion of the starting conductor 200 and possibly be included in the starting circuit breaker 20.The fusible element 21 is arranged to melt when a current of an intensity greater than a predetermined threshold value flows in the initiation conductor 200.

[0038] One of the two terminals of the disconnecting device 2 is connected to one of the terminals of the main electrical conductor 100, and the other of the two terminals of the disconnecting device 2 is intended to be connected to the electrical circuit. The main electrical conductor 100 is arranged to be connected in series to the electrical circuit.

[0039] In the disconnecting device 2, the breaking voltages of the initiating circuit breaker 20 and the fusible element 21 are lower than the supply voltage of the electrical circuit, so that in the event of a break in the initiating conductor 200 or a melting of the fusible element 21, an electric current continues to flow in the electrical circuit with the formation of an electric arc at the physical break in the initiating conductor 200. Conversely, the breaking voltage of the main pyrotechnic circuit breaker 1 is strictly greater than the supply voltage of the electrical circuit, so that no electric current can flow once the main electrical conductor 100 is broken.

[0040] In the first configuration, where a nominal electric current below the predetermined threshold value flows through the electronic circuit, only a negligible portion of the nominal electric current passes through the resistive element 11 (which may correspond to a leakage current). Thus, only the igniter conductor 200, the fusible element 21, and the main electrical conductor 100 carry the nominal electric current in this first configuration, and the fusible element 21 can be considered as being connected in series with the main pyrotechnic circuit breaker 1. It can be noted that in the first configuration, the total resistance of the igniter conductor 200 and the fusible element 21 is zero or negligible, so the resistive element 11 "protects" the main electro-pyrotechnic igniter 10, which is neither activated nor ignited.

[0041] In a second configuration, where an electrical current exceeding the predetermined threshold value flows through the electronic circuit, the fusible element 21 melts and / or, if the electronic control unit (ECU) sends the ignition signal to the pyrotechnic ignition actuator 201, the ignition conductor 200 is severed. However, an electrical current continues to flow through the ignition conductor 200 via an electric arc. Due to the greater electrical resistance of the electric arc compared to the resistance of the unsevered ignition conductor 200 and / or compared to an intact fusible element 21, the voltage across the disconnecting device 2 increases compared to the first configuration and exceeds a trigger voltage. A sufficiently strong electrical current then flows through the resistive element 11 to actuate or ignite the main electro-pyrotechnic igniter 10.Thus, it is the voltage across the terminals of the disconnecting device 2, during the formation of an electric arc in the disconnecting device 2, that generates the current interruption signal sent to the main electro-pyrotechnic igniter 10. The main electro-pyrotechnic igniter 10 does not require an external power source to trigger its ignition. Once the signal... When the current is cut off, the main pyrotechnic circuit breaker 1 cuts the main electrical conductor 100 so that no further passage of electric current is possible.

[0042] Figure 2 shows a cross-sectional view of the priming circuit breaker 20 comprising: - the 200 priming driver, - the pyrotechnic priming actuator 201, - a 202 piston, - a 203 matrix. The pyrotechnic priming actuator 201 is arranged on one side of the priming cut-off switch 20 and is initiated when the priming cut-off switch 20 receives the priming signal from the electronic control unit ECU (not shown in Figure 2). The pyrotechnic initiation actuator 201 generates hot gases, and pressure is applied against the piston 202, forcing it to move towards the initiation conductor 200. The piston 202 includes a single cutting blade 2020 arranged opposite a cut portion 2000 of the initiation conductor 200. This arrangement is designed to sever the initiation conductor 200. The initiation conductor 200 is arranged to pass through the initiation cut-off switch 20, forming two terminals of the cut-off switch 20 and the cut portion 2000 intended to be severed. The die 203 is arranged on the other side of the initiation cut-off switch 20 to support the initiation conductor 200.Once the cutting portion 2000 is sectioned to form two free ends to the initiating conductor 200, the cutting blade 2020 ends its stroke by being stopped by the die 203. According to an alternative embodiment, the cutting portion 2000 can be arranged or defined as a fusible element which can advantageously replace the fusible element 21 making the sectioning device 2 more compact.

[0043] The 20 priming circuit breaker is intended or chosen to ensure the interruption of the electrical current in the electrical circuit only for voltages lower than its breaking voltage. In other words, the initiating circuit breaker 20 is a low-voltage circuit breaker, or at the very least has a breaking voltage lower than that of the electrical circuit it is protecting. Thus, if the initiating circuit breaker 20 is triggered while the electrical circuit is supplied with a high voltage, electric arcs will form and persist between the free ends of the initiating conductor 200 because the initiating circuit breaker 20 does not have the capacity to interrupt the current to which it is subjected.

[0044] Figure 3 shows a cross-sectional view of the main pyrotechnic circuit breaker 1 comprising: - the electro-pyrotechnic igniter 10, - the main electrical conductor 100, - a main piston 101, - a principal matrix 102. The electro-pyrotechnic igniter 10 is arranged at one end of the main pyrotechnic circuit breaker 1 and is activated when the main pyrotechnic circuit breaker 1 receives the current interruption signal corresponding to an influx of electrical current. The electro-pyrotechnic igniter 10 generates hot gases, and pressure is applied against the main piston 101, causing it to move. The main piston 101 includes at least three cutting blades designed to cut the main electrical conductor 100 to form a first folded portion 1001, a second cut portion 1002, and a third cut portion 1003. In other words, the main electrical conductor 100 is cut to form two free strands (the second cut portion 1002 and the third cut portion 1003) in this example.The main electrical conductor 100 is arranged passing through the main pyrotechnic circuit breaker 1, forming two terminals and resting on the main cutting die 102. The main cutting die 102 forms three protruding ends arranged opposite the cutting blades of the main piston 101, so that the cutting blades of the main piston 101. insert between the protruding ends of the main matrix 102 once the main electrical conductor 200 has been cut.

[0045] When the main pyrotechnic circuit breaker 1 is activated, the second cutting portion 1002 and the third cutting portion 1003 form free strands, i.e., not connected or linked to the main electrical conductor 100. It is also possible to compartmentalize the cutting chambers with the main cutting piston 101 and the main die 102. These features give the main pyrotechnic circuit breaker 1 a breaking voltage higher than the high supply voltage of the electrical circuit to be protected and guarantee that there is no current flow in the electrical circuit once the main electrical conductor 100 is severed.

[0046] In summary, the disconnecting device 2 is designed not to act as a circuit breaker for the electrical circuit to be protected, but the activation of the disconnecting device 2 causes the generation of a voltage across its terminals, which is sufficient to trigger the main pyrotechnic circuit breaker 1. With the fusible element 21 and the initiation circuit breaker 20, the possibility of providing a passive or active interruption of the electrical circuit is offered.

[0047] Coupling the main high-voltage pyrotechnic circuit breaker 1 to the disconnecting device 2 with its low-voltage components provides a protection system that is resistant to aging, with low-voltage components, and is also inexpensive.

[0048] Figure 4 shows an embodiment in which the fusible element 21 forms part of the igniter conductor 20. The circuit breaker in Figure 4 shows, on the left of the figure, the main electro-pyrotechnic igniter 10, arranged to trigger a movement of the piston 101 and thus interrupt the main electrical conductor 100. On the right of Figure 4 is illustrated the disconnecting device 2. including the pyrotechnic initiation actuator 201 arranged to move the piston 202 against the fusible element 21 which is for example a thin sheet arranged in series with the two ends of the initiation conductor 200. The fusible element 21 is therefore the portion of the initiation conductor 200 which will be cut by the piston 202 of the initiation circuit breaker 20 during its downward movement in Figure 4 in this embodiment.

[0049] Figure 5 shows an alternative embodiment comprising a transient voltage suppression diode 12 (also called a Transil diode or transient-voltage-suppression diode in English) on a branch of the circuit in parallel with the switching device 2. The transient voltage suppression diode 12 makes it possible to block or at least strongly limit the passage of current in the branch of the circuit parallel to the switching device 2 comprising the main electro-pyrotechnic igniter 10, when the voltage applied across its terminals is less than a diode threshold voltage (typically when the voltage across the diode is less than 90 V or 100 V).Consequently, when the igniter 2 interrupts the igniter conductor 20 (or the fusible element 21) while the voltage between the first and second terminals of the disconnecting device is low, no current flows through the main pyrotechnical cut-off switch 1, or only a negligible current flows through the main pyrotechnical cut-off switch 1. The circuit can be considered isolated even when the supply voltage is too low to trigger the main electro-pyrotechnic igniter 10 and physically interrupt the main electrical conductor 100.

[0050] When the voltage across the transient voltage suppression diode 12 increases, typically when the supply voltage increases, and exceeds the diode's threshold voltage, current flow is again permitted in the electro-pyrotechnic igniter. main 10. The rating of the transient voltage suppression diode 12 is chosen so that the diode threshold voltage is sufficient for the current intensity after passing through the transient voltage suppression diode 12 to systematically trigger the interruption of the main electrical conductor 100 by the main pyrotechnic circuit breaker 1. Industrial application

[0051] An electrical circuit protection system according to the present invention, and its manufacture, are capable of industrial application.

[0052] It will be understood that various modifications and / or improvements obvious to a person skilled in the art can be made to the different embodiments of the invention described in this description without departing from the scope of the invention.

Claims

DEMANDS

1. A system for protecting an electrical circuit, comprising: - a main pyrotechnic circuit breaker (1) comprising: • a main electrical conductor (100) arranged to be connected to the electrical circuit, • a main electro-pyrotechnic igniter (10) arranged to be triggered and cause the main electrical conductor (100) to be interrupted, - a circuit breaker (2) comprising: • a first terminal and a second terminal, • a fusible element (21) one terminal of which corresponds to one of the first and second terminals of the disconnecting device (2), • a starting circuit breaker (20) comprising: ■ a starting conductor (200) one terminal of which corresponds to the other of the first and second terminals of the disconnecting device (2), ■ a pyrotechnic initiation actuator (201) arranged to be controlled by an electronic control unit so as to interrupt the initiation conductor (200), characterized in that a initiation circuit breaker cutoff voltage (20) and a breaking voltage of the fusible element (21) are each less than a supply voltage of the electrical circuit, and in that the main electro-pyrotechnic igniter (10) is connected on one side to the first terminal of the disconnecting device (2) and on the other side to the second terminal of the disconnecting device (2) to be triggered by the disconnecting device (2).

2. A protection system for an electrical circuit according to claim 1, wherein the fusible element (21) is connected in series with the initiation conductor (200) of the initiation circuit breaker (20), and / or wherein the fusible element (21) forms at least in part the initiation conductor (200) of the initiation circuit breaker (20).

3. A protection system for an electrical circuit according to any one of claims 1 or 2, wherein the initiating circuit breaker (20) comprises a single cutting blade (2020), and / or does not generate an electrically free strand when the initiating conductor (200) is interrupted.

4. A protection system for an electrical circuit according to any one of claims 1 to 3, comprising a resistive element (11) connected in series with the main electro-pyrotechnic igniter (10) and with either of the first terminal of the disconnecting device (2) and the second terminal of the disconnecting device (2), and having a resistance value between 20 and 100 ohms, and preferably between 50 and 100 ohms, and having a resistance value preferably of 80 ohms.

5. A protection system for an electrical circuit according to any one of claims 1 to 4, wherein the supply voltage of the electrical circuit is between 100 V and 5000 V, preferably between 200 V and 4000 V, preferably between 250 V and 2500 V.

6. A protection system for an electrical circuit according to any one of claims 1 to 5, wherein the breaking voltage of the initiating circuit breaker (20) and the breaking voltage of the fusible element (21) are each less than two times, preferably five times, preferably ten times the supply voltage.

7. A protection system for an electrical circuit according to any one of claims 1 to 6, wherein a breaking voltage of the main pyrotechnic circuit breaker (1) is greater than 1000 V and preferably 1500 V and / or wherein a breaking voltage of the circuit breaker main pyrotechnic (1) is greater than 1.5 times, preferably 2 times, preferably 2.5 times the supply voltage.

8. A protection system for an electrical circuit according to any one of claims 1 to 7, wherein the main pyrotechnic circuit breaker (1) is arranged to cut at least one free strand of the main electrical conductor (100) when the main electrical conductor (100) is cut, and preferably at least two free strands.

9. A protection system for an electrical circuit according to any one of claims 1 to 8, comprising an electronic control unit arranged to trigger the pyrotechnic priming actuator (201).

10. Motor vehicle, comprising: - an electrical circuit with a traction battery and / or a traction motor, - an electrical circuit protection system, according to any one of claims 1 to 9 - the electronic control unit arranged to control the firing of the priming circuit breaker (20).

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