Pyrotechnic battery disconnect system and associated operating method

Abstract

The invention relates to a pyrotechnic battery disconnect system (1) having an electric high-voltage battery (2) with a low side at low-voltage potential (LV) and a high side at high-voltage potential (HV), a pyro fuse (4) for electrically disconnecting the high-voltage battery (2), wherein the pyro fuse (4) is connected in series with the high-voltage battery (2) and is arranged on the high side of the high-voltage battery (2) such that the pyro fuse (4) is at the high-voltage potential (HV), and having a control circuit (7) with a trip output for tripping the pyro fuse (4), wherein the pyro fuse (3) cuts off the high-voltage battery (2) upon tripping. According to the invention, the control circuit (7) is likewise arranged on the high side of the high-voltage battery (2) and is at the high-voltage potential (HV) in order, when the pyro fuse (4) trips, to avoid a brief short circuit between the high-voltage potential (HV) of the pyro fuse (4) and the low-voltage potential (LV). Furthermore, the invention comprises an associated operating method.

Description

[0001] DESCRIPTION

[0002] Pyrotechnic battery separation system and associated operating procedure

[0003] Technical field of the invention

[0004] The invention relates to a pyrotechnic battery disconnect system, in particular for a vehicle electrical system of a battery-electric vehicle or a hybrid vehicle. Furthermore, the invention includes a corresponding operating method.

[0005] Background of the invention

[0006] In modern electric cars (BEV: Battery Electric Vehicle) and hybrid cars (PHEV: Plug-in Hybrid Electric Vehicle), high-voltage batteries with a battery voltage of more than 60 volts are used to power the electric drive motors. For example, high-voltage batteries with a battery voltage of 400 volts or 800 volts are already in use. Due to the high battery voltage of such high-voltage batteries, electrical protection of the high-voltage battery is important in order to quickly and reliably disconnect the high-voltage battery from the vehicle's electrical system in the event of an accident or a fault-related overcurrent. For this purpose, so-called pyrofuses ("pyrofuses") are used. These contain an electrically triggered detonator that quickly and reliably interrupts the electrical circuit ("busbar") with a small explosion.Such pyrofuses are marketed, for example, by the German company Miba AG under the product name "Miba POWERfuse®." The pyrofuses are typically located on the high side of the high-voltage battery in a high-voltage area, while the pyrofuses are controlled by a control circuit located in a low-voltage area.

[0007] The problem here is the fact that when the pyro-fuse is triggered, a short circuit occurs briefly between the pyro-fuse in the high-voltage area and the control circuit in the low-voltage area.

[0008] The invention is therefore based on the object of improving known pyrotechnic battery separation systems so that even when the pyroelectric fuse is triggered, no brief short circuit occurs between the high-voltage and low-voltage areas. Furthermore, the invention is based on the object of specifying a corresponding operating method for such a pyrotechnic battery separation system.

[0009] This object is achieved by a pyrotechnic battery separation system according to the invention or by a corresponding operating method according to the independent claims.

[0010] The pyrotechnic battery separation system according to the invention initially comprises, in accordance with the prior art, a high-voltage electric battery with a high side and a low side. In the preferred embodiment of the invention, the high-voltage battery is rechargeable; however, it is also possible in principle to implement the invention with a non-rechargeable battery. Furthermore, it should be noted that the high-voltage battery preferably delivers a battery voltage of more than 60 V, 200 V, 400 V, 600 V, or 800 V. However, the invention is not limited to the aforementioned exemplary values ​​with regard to the battery voltage.

[0011] Furthermore, the pyrotechnic battery disconnection system according to the invention, in accordance with the prior art described above, comprises a pyro-fuse to quickly and reliably disconnect the high-voltage battery in the event of an accident or a fault-related overcurrent. The pyro-fuse is connected in series with the high-voltage battery and arranged on the high side of the high-voltage battery, so that the pyro-fuse is at the high-voltage potential. Such pyro-fuses are known per se from the prior art and therefore need not be described in detail. For example, such pyro-fuses can be purchased from the German company Miba AG under the product name "Miba POWERfuse®." However, the invention is not limited to this type of pyro-fuse, but can also be implemented with other types of pyro-fuses.

[0012] Furthermore, the pyrotechnic battery disconnection system according to the invention, in accordance with the prior art, comprises a control circuit for triggering the pyro-fuse in the event of an accident or a fault-related overcurrent, whereby the pyro-fuse then disconnects the high-voltage battery when triggered by the control circuit. The invention is distinguished from the prior art in that the control circuit is also arranged on the high side of the battery and is at the high-voltage potential in order to prevent a brief short circuit between the high-voltage potential of the pyro-fuse on the one hand and the low-voltage potential on the other hand when the pyro-fuse is triggered.In the pyrotechnic battery separation system according to the invention, both the pyro-fuse and the control circuit are both at the high-voltage potential, so that the short circuits that briefly occur between the pyro-fuse on the one hand and the control circuit on the other hand when the pyro-fuse is triggered by the control circuit no longer have any harmful effects, as they occur in the prior art described at the beginning.

[0013] It should be noted that the low-voltage potential can be the chassis ground of the power supply. However, within the scope of the invention, it is also possible for the low-voltage potential to be a higher potential that lies above the chassis ground of the power supply. The only decisive factor within the scope of the invention is that the low-voltage potential is significantly lower than the high-voltage potential.

[0014] Furthermore, the pyrotechnic battery separation system according to the invention preferably comprises an electrical energy storage device to provide the electrical energy required to trigger the pyroelectric fuse. For example, this electrical energy storage device can be a capacitor (e.g., a double-layer capacitor, supercapacitor). However, the invention is not limited to capacitors with regard to the type of electrical energy storage device, but can also be implemented in principle with other types of energy storage devices that can deliver a sufficiently large trigger current sufficiently quickly to trigger the pyroelectric fuse.

[0015] Furthermore, the pyrotechnic battery separation system according to the invention preferably comprises a controllable switching element for connecting the electrical energy storage device (e.g., capacitor) to the pyroelectric fuse for triggering the pyroelectric fuse. The switching element is controllable via a trigger output of the control circuit. In the preferred embodiment of the invention, the switching element is a power transistor (e.g., MOSFET: metal oxide semiconductor field-effect transistor), but the invention is also fundamentally feasible with other types of switching elements.

[0016] To trigger the pyroelectric fuse, the control circuit then activates the switching element so that the energy storage device (e.g., capacitor) is connected to the pyroelectric fuse for a specific triggering period. During this triggering period, a specific triggering current flows through the pyroelectric fuse to trigger it. The triggering current and the triggering period together are thus sufficiently large to trigger the pyroelectric fuse.

[0017] It should be noted that the tripping current, together with the tripping duration, must be appropriately dimensioned to trigger the pyro-fuse. For example, a very high tripping current with an extremely short tripping duration may not be sufficient to trigger the pyro-fuse. Furthermore, a very long tripping duration with a correspondingly short tripping current may not be suitable for triggering the pyro-fuse. In the preferred embodiment of the invention, the tripping current is at least 500 mA, 1 A, or 2 A, while the tripping duration is at least 500 ps, ​​1 ms, 2 ms, or 4 ms. However, the suitable values ​​for the tripping current and tripping duration depend on the specifications of the pyro-fuse and can therefore vary.

[0018] It should also be noted that the control circuit is preferably designed as an integrated circuit (IC). However, within the scope of the invention, it is also possible for the control circuit to be a discrete circuit or for its functions to be distributed across various components.

[0019] In the preferred embodiment of the pyrotechnic battery separation system according to the invention, a current limiter is arranged between the electrical energy storage device (e.g. capacitor) and the pyro-fuse in order to limit the triggering current to a maximum value and thus keep the triggering current as constant as possible during the triggering period. This makes it possible to design the energy storage device smaller, i.e. due to the current limitation, a smaller capacity of the energy storage device is sufficient. For example, the maximum value of the triggering current specified by the current limiter can be a maximum of 5 A, 3 A or 2 A. Due to this current limitation, the triggering current fluctuates less during the triggering period. Without current limitation, the triggering current decreases exponentially during the triggering period in accordance with the discharge curve of a capacitor and thus fluctuates greatly.With the current limitation according to the invention, the fluctuations in the tripping current during the tripping period between the switching edges can be reduced to less than 50%, 30%, 20%, 10%, or even less than 5%. As already mentioned above, this offers the advantage that an energy storage device with a lower capacity is sufficient. In the preferred embodiment of the invention, the current limiter can be implemented in circuitry using a constant current source; however, other designs for the current limiter are also possible within the scope of the invention.

[0020] Furthermore, it should be mentioned that a transformer can be provided to charge the electrical energy storage device (e.g. capacitor), which receives a supply voltage (e.g. +12V) on the input side and provides a higher charging voltage (e.g. +48V) on the output side to charge the energy storage device.

[0021] It was already mentioned above that the pyro-fuse should, among other things, be triggered in the event of an overcurrent, i.e. when an excessively high battery current flows during operation due to a fault. To measure the battery current, a first current sensor is therefore preferably provided, which measures the battery current, with the control circuit interrogating the first current sensor via a first measuring input. The control circuit then triggers the pyro-fuse if an evaluation of the measured battery current indicates an overcurrent, in particular if the measured battery current exceeds a predetermined maximum value. When an overcurrent is detected by the control circuit, the duration of the current increase can be taken into account in addition to the level of the battery current.

[0022] In the preferred embodiment of the invention, the first current sensor has a low-ohm current measuring resistor ("shunt") connected in series with the high-voltage battery, so that the battery current also flows through the first low-ohm current measuring resistor. The control circuit then measures the voltage drop across the first low-ohm current measuring resistor via the first measuring input, wherein the measured voltage drop across the first low-ohm current measuring resistor is then, according to Ohm's law, a measure of the battery current flowing through the first low-ohm current measuring resistor. The first low-ohm current measuring resistor preferably has a small resistance value of less than 100 mΩ, 50 mΩ, 10 mΩ, 5 mΩ, 1 mΩ, 500 pΩ, 250 pΩ, or 100 pΩ.

[0023] It should also be mentioned that the first current sensor is preferably arranged on the high side of the high-voltage battery. This is advantageous because then no potential difference needs to be bridged between the control circuit, which is at the high-voltage potential, on the one hand, and the first current sensor, which is at the high-voltage potential, on the other. However, within the scope of the invention, it is also fundamentally possible for the first current sensor to be arranged on the low side of the high-voltage battery. The pyrotechnic battery isolation system according to the invention preferably also enables a test of the pyro-fuse, wherein the pyro-fuse is not triggered during the test. For this purpose, the control circuit can have a test output that enables a test of the pyro-fuse. During a test process, the control circuit then drives a test current through the pyro-fuse, wherein the test current is so small that it is insufficient to trigger the pyro-fuse.To measure the test current during a test procedure, the pyrotechnic battery isolation system preferably has a second current sensor, which is queried via a second measuring input of the control circuit. The control circuit can then detect a fault in the pyroelectric fuse by evaluating the test current flowing during a test procedure.

[0024] It should be noted that the test output of the control circuit can be a digital output. Furthermore, the test current should preferably be less than 1 A, 500 mA, 250 mA, or 100 mA to prevent the pyroelectric fuse from being triggered by the test current. However, the magnitude of the test current depends on the specifications of the respective pyroelectric fuse and can therefore vary depending on the specific pyroelectric fuse. The only important thing is that the test current is low enough that the pyroelectric fuse is not triggered by the test current.

[0025] The second current sensor for measuring the test current can function in the same way as the first current sensor for measuring the battery current. For this purpose, the second current sensor can have a second low-ohm current measuring resistor, which is arranged between the test output of the control circuit and the pyroelectric fuse and through which the test current flows during the test process. The control circuit then measures the voltage drop across the second low-ohm current measuring resistor via the second measuring input, which, according to Ohm's law, provides a measure of the test current. For example, the second low-ohm current measuring resistor can have a resistance value of less than 100 mΩ, 50 mΩ, 10 mΩ, 5 mΩ, 1 mΩ, 500 pΩ, 250 pΩ, or 100 pΩ.

[0026] It is also possible to connect a series resistor in series with the second low-ohm current measuring resistor to limit the test current. This limitation of the test current also prevents the test current from causing the pyroelectric fuse to be triggered unintentionally. When using such a series resistor, it is also possible to use the series resistor to measure the current by measuring the voltage drop across the series resistor. In this case, a low-ohm current measuring resistor is not required to measure the test current, i.e. the series resistor can be used to measure the current and does not have to be low-ohm. It was already mentioned above that the pyroelectric fuse should be triggered in the event of an accident (crash), among other things. For this purpose, the control circuit preferably has an interface connection that enables the recording of a crash signal triggered by a crash sensor.For example, the crash sensor can be an airbag sensor that sends the crash signal to a battery management system (BMS), which then triggers the charging circuit for the pyrotechnic fuse. Alternatively, it is possible for the control circuit of the pyrotechnic battery isolation system according to the invention to also contain the functions of the battery management system (BMS), so that the battery management system is integrated into the control circuit. The control circuit can then receive the crash signal via the interface connection.

[0027] A potential separation element is preferably connected to the interface connection of the control circuit in order to decouple the control circuit, which is at the high-voltage potential, from the crash signal from the low-voltage range.

[0028] It should be noted that the interface connection of the control circuit preferably enables not only the reception of a crash signal, but also the reception and retransmission of a diagnostic signal. The diagnostic signal preferably differs from the crash signal, so that the control circuit can distinguish the incoming diagnostic signal from the crash signal and does not trigger the pyroelectric fuse when the incoming diagnostic signal is received. For example, the diagnostic signal can have a different signal level or a different signal shape than the crash signal to enable differentiation. In the preferred embodiment of the invention, the diagnostic signal has a significantly lower signal level than the crash signal.

[0029] It was already mentioned above that the interface connection preferably also enables the reception and retransmission of a diagnostic signal. Thus, the diagnostic signal for a diagnosis is first transmitted to the control circuit, and the control circuit then responds, if functioning correctly, by retransmitting the diagnostic signal. To enable such retransmission of the diagnostic signal, the aforementioned potential isolation element preferably enables bidirectional data transmission, namely data transmission to the control circuit in a first transmission channel and data transmission back from the control circuit in a second transmission channel. The two transmission channels of the potential isolation element are preferably combined towards the control circuit and jointly connected to the interface connection of the control circuit.To the outside, however, the two transmission channels of the potential isolation element are preferably separated from each other. It should also be noted that data transmission in the two transmission channels can be either analog or digital.

[0030] In addition, the control circuit preferably has a charging control output to control the charging process for charging the electrical energy storage device (e.g., capacitor). The charging control output of the control circuit preferably controls a controllable second switching element (e.g., power transistor, MOSFET), wherein the second switching element selectively connects the electrical energy storage device (e.g., capacitor) to the transformer or disconnects it from the transformer. In addition, the control circuit preferably has a third measuring input connected to the energy storage device to measure the charging voltage at the energy storage device. By measuring the charging voltage and correspondingly controlling the second switching element, the control circuit can then control the charging process.

[0031] In the preferred embodiment of the invention, the control circuit preferably has an analog / digital converter at each of its measurement inputs for battery current, test current, or charging current, as well as at the interface connection, to enable internal digital data processing. However, it is also possible to provide only one analog / digital converter, which, however, has multiple measurement channels.

[0032] It was already mentioned above that the control circuit triggers the pyroelectric fuse in the event of an accident (crash) or an overcurrent. In the preferred embodiment, the control circuit triggers the pyroelectric fuse in both cases. However, the invention also claims protection for a pyrotechnic battery isolation system in which the pyroelectric fuse is triggered only in one of the two cases or additionally in another case.

[0033] Furthermore, it should be noted that the aforementioned parts and components are preferably integrated into a common assembly, which can be arranged in a common housing. For example, this common assembly can contain the following components:

[0034] • The first current sensor to measure the battery current,

[0035] • the control circuit for triggering the pyro-fuse,

[0036] • the energy storage to provide the energy to trigger the pyro-fuse, • the second current sensor to measure the test current,

[0037] • the transformer to provide the charging voltage for the energy storage device,

[0038] • the potential separation element,

[0039] • the first switching element for connecting the energy storage device with the pyro-fuse,

[0040] • the second switching element for connecting the energy storage device to the transformer,

[0041] • the diode,

[0042] • the series resistor to limit the test current,

[0043] • the current limiter to limit the tripping current, and / or

[0044] • a microcontroller for communication with the control circuit.

[0045] The pyrotechnic battery disconnection system according to the invention has been described above, which can be used, for example, in a motor vehicle electrical system. However, the invention also claims protection for a complete motor vehicle electrical system with such a pyrotechnic battery disconnection system according to the invention.

[0046] Furthermore, it should be noted that the invention is not limited to use in a motor vehicle electrical system. Rather, the pyrotechnic battery disconnection system according to the invention can also be used in stationary systems.

[0047] Furthermore, within the scope of the invention, it is also possible for the pyrotechnic battery separation system according to the invention to be used in other types of vehicles which have an on-board electrical system, such as rail vehicles (e.g. locomotives, railcars, freight cars, passenger coaches), aircraft (e.g. airplanes, helicopters), spacecraft (e.g. rockets, space gliders, space stations) or watercraft (e.g. ships, boats, submarines).

[0048] Furthermore, it should be noted that the invention also claims protection for a complete motor vehicle with such a vehicle electrical system featuring the pyrotechnic battery disconnect system according to the invention. The motor vehicle can be, for example, a battery electric vehicle (BEV) or a hybrid vehicle (PHEV: Plug-in Hybrid Electric Vehicle).

[0049] Finally, the invention also claims protection for a corresponding operating method, wherein the individual method steps of the operating method according to the invention already result from the above description of the pyrotechnic battery separation system according to the invention, so that a separate description of the operating method according to the invention can be dispensed with.

[0050] Other advantageous developments of the invention are characterized in the subclaims or are explained in more detail below together with the description of the preferred embodiment of the invention with reference to the figures.

[0051] Figure 1 shows a schematic representation of a circuit diagram of a pyrotechnic battery separation system according to the invention.

[0052] Figure 2 shows a flow chart to illustrate the operating method of the pyrotechnic battery separation system according to the invention.

[0053] Detailed information

[0054] The circuit diagram of a pyrotechnic battery separation system 1 according to the invention shown in Figure 1 will now be described.

[0055] The pyrotechnic battery separation system shown is used to separate a high-voltage battery 2 in a motor vehicle electrical system of a battery electric vehicle (BEV), wherein for the sake of simplicity only the high-voltage battery 1 and an on-board electrical system cable 3 are shown from the motor vehicle electrical system.

[0056] A pyroelectric fuse 4 is arranged on the high side of the high-voltage battery 2 in the vehicle electrical system line 3 of the vehicle electrical system and is connected in series with the high-voltage battery 2. The pyroelectric fuse 4 enables the high-voltage battery 2 to be quickly and reliably disconnected from the vehicle electrical system in the event of an accident (crash) or a fault-related overcurrent.

[0057] The pyrotechnic battery separation system 1 consists of a high-voltage area 5 at high-voltage potential HV (high voltage) and a low-voltage area 6 at low-voltage potential LV (low voltage). It should be noted that the low-voltage potential LV can be the ground potential ("chassis ground") of the power supply. However, within the scope of the invention, it is also possible for the low-voltage potential LV to be a higher potential that lies above the ground potential ("chassis ground") of the power supply. The only decisive factor within the scope of the invention is that the low-voltage potential LV is significantly lower than the high-voltage potential HV.

[0058] In the high-voltage area 5 of the pyrotechnic battery separation system 1 there is a control circuit 7 which is designed as an integrated circuit and controls the operation of the pyrotechnic battery separation system 1.

[0059] When the motor vehicle is in operation, a battery current IBAT flows through the on-board power supply line 3, which can be measured by a low-resistance current measuring resistor 8, wherein the control circuit 7 has a measuring input 9 in order to measure a measuring voltage UMESS ZU dropped across the low-resistance current measuring resistor 8. The measuring voltage UMESS then forms a measure of the battery current IBAT flowing through the current measuring resistor 8 in accordance with Ohm's law. It should be noted that the measuring input 9 of the control circuit 7 has an analog / digital converter which converts the analog measured value of the measuring voltage UMESS into a corresponding digital value and enables digital signal processing in the control circuit 7. In this way, the control circuit 7 can detect an overcurrent, which then enables the pyroelectric fuse 4 to be triggered, as will be described in more detail.

[0060] In addition, the pyrotechnic battery separation system 1 has a capacitor 10 to provide the electrical energy required to trigger the pyro-fuse 4. The capacitor 10 is connected to the pyro-fuse 4 via a MOSFET 11, wherein the MOSFET 11 is controlled via a trigger output 12 of the control circuit 7. To trigger the pyro-fuse 4, the control circuit 7 controls the MOSFET 11 so that the MOSFET 11 switches on, thus connecting the capacitor 10 to the pyro-fuse 4. The capacitor 10 then discharges via the switched-on MOSFET 11 into the pyro-fuse 4, whereby a trigger current IPYRO flows, which is sufficiently large and lasts sufficiently long to trigger the pyro-fuse 4. For example, the trigger current I P YRO=2A.

[0061] The control circuit 7 also has the task of controlling the charging process of the capacitor 10. For this purpose, the control circuit 7 has a measuring input 13 with an analog / digital converter for measuring the charging voltage ULADE across the capacitor 10. If an insufficient charging voltage ULADE is measured, the control circuit 7 can then control a switching element 15 via a charging control output 14 to connect the capacitor 10 to a transformer 16. The transformer 16 is fed on the input side by a lower supply voltage Uv=+12V. In addition to the above-described control of the charging process of the capacitor 10, measuring the charging voltage ULADE can also be used for diagnostic purposes. For example, by measuring the charging voltage ULADE, the control circuit 7 can determine whether sufficient electrical energy is stored in the capacitor 10 to trigger the pyroelectric fuse 4.

[0062] In addition, the control circuit 7 also enables a test of the pyro-fuse 4. For this purpose, the control circuit 7 can drive a small test current ITEST through the pyro-fuse 4, whereby the test current ITEST is SO small that it does not trigger the pyro-fuse 4. For this purpose, the control circuit 7 has a digital test output 17 at which the test current ITEST is output. The test output 17 is connected to the pyro-fuse 4 via a low-ohm current measuring resistor 18 and a diode 19. The low-ohm current measuring resistor 18 enables the test current ITEST to be measured by the control circuit 7. For this purpose, the control circuit 7 has a further measuring input 20 with an analog / digital converter in order to measure the electrical voltage drop across the low-ohm current measuring resistor 18, which voltage forms a measure of the test current ITEST according to Ohm's law.In this way, the control circuit 7 can detect a possible malfunction of the pyro-fuse 4.

[0063] In addition, the control circuit 7 has an interface connection 21 with an analog / digital converter. The interface connection 21 of the control circuit 7 is connected via a potential isolation element 22 to a battery management system 23 (BMS), which receives a crash signal from a crash sensor in the event of an accident. Communication between the battery management system 23 and the control circuit 7 is possible. The battery management system 23 transmits a signal 24 to the control circuit 7, which evaluates the signal 24. At a high signal level 25, the control circuit 7 detects an accident (crash) and then triggers the pyroelectric fuse 4. At a low signal level 26 of the signal 24, however, the control circuit 7 detects a diagnostic signal and then responds with a corresponding diagnostic signal 27, which is transmitted back from the control circuit 7 to the battery management system 23.In this way, the battery management system 23 can detect whether the control circuit 7 is working correctly, since in the event of a malfunction of the control circuit 7, the diagnostic signal 27 is not transmitted back.

[0064] Alternatively, within the scope of the invention, it is also possible for the battery management system 23 (BMS) to be integrated into the control circuit 7. The flowchart according to Figure 2, which describes the operating method of the pyrotechnic battery separation system 1 according to the invention, will now be described.

[0065] It should be noted that the individual process steps include testing the pyroelectric fuse 4 (steps S1-S4), the external diagnosis of the control circuit 7 (steps S5-S7), and the actual fault check and triggering of the pyroelectric fuse 4 (steps S8-S12). It should be noted that the testing, diagnosis, checking, and triggering do not necessarily have to occur in the order shown.

[0066] In a first step S1, the test current ITEST is first driven through the pyro-fuse 4 in order to test it.

[0067] In a second step S2, the test current ITEST is then measured and evaluated in the control circuit 7 in order to detect a possible malfunction of the pyro-fuse 4.

[0068] If it is determined in step S3 that there is a malfunction of the pyro-fuse 4, an error message follows in step S4.

[0069] Otherwise, in a step S5, the signal 24 with the small signal level 26 is transmitted from the battery management system 23 to the control circuit 7 as a diagnostic signal.

[0070] The battery management system 23 then checks in step S6 whether the diagnostic signal 27 is being retransmitted. If this is not the case, an error message follows in step S7.

[0071] Otherwise, a step S8 checks whether the crash signal 25 is received by the battery management system 23 in the control circuit 7. If this is the case, the pyroelectric fuse 4 is triggered in a step S9.

[0072] Otherwise, the battery current IBAT is measured in step S10.

[0073] In the next step S11, the battery current IBAT is evaluated to detect an overcurrent situation. If an overcurrent situation is detected in step S12, the pyroelectric fuse is triggered in step S9.

[0074] Otherwise, the operating procedure is repeated in a loop.

[0075] The invention is not limited to the preferred embodiment described above. Rather, a multitude of variants and modifications are possible, which also utilize the inventive concept and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and features of the subclaims, independently of the respective claims referred to, and in particular even without the features of the main claim. The invention thus encompasses various aspects of the invention that enjoy independent protection.

[0076] 1 Pyrotechnic battery separation system

[0077] 2 high-voltage batteries

[0078] 3 On-board power supply cable

[0079] 4 Pyro fuse

[0080] 5 High-voltage area of ​​the pyrotechnic battery separation system

[0081] 6 Low voltage range of the pyrotechnic battery separation system

[0082] 7 Control circuit for triggering the pyroelectric fuse

[0083] 8 Low-ohm current measuring resistor ("shunt") for measuring the battery current IBAT

[0084] 9 Measuring input of the control circuit with analog / digital converter for measuring the battery current IBAT

[0085] 10 Capacitor to provide the energy to trigger the pyro-fuse

[0086] 11 MOSFET to connect the capacitor to the pyro fuse when the pyro fuse is triggered

[0087] 12 Trigger output of the control circuit for triggering the pyro-fuse

[0088] 13 Measuring input of the control circuit with analog / digital converter for measuring the charging voltage

[0089] 14 Charging control output of the control circuit

[0090] 15 Switching element for connecting the transformer to the capacitor

[0091] 16 transformers for charging the capacitor

[0092] 17 Digital test output for driving the test current ITEST through the pyro fuse

[0093] 18 Low-ohm current measuring resistor ("shunt") for measuring the test current ITEST through the pyro-fuse

[0094] 19 Diode

[0095] 20 Measuring input of the control circuit with analog / digital converter for detecting the test current ITEST through the pyro-fuse

[0096] 21 Interface connection of the control circuit with analog / digital converter for receiving the crash signal as well as for receiving and retransmitting the diagnostic signal

[0097] 22 Potential separation element

[0098] 23 Battery Management System (BMS)

[0099] 24 Signal to the interface connection of the control circuit

[0100] 25 Large signal level as trigger signal in case of a crash

[0101] 26 Small signal level as diagnostic signal 27 Diagnostic signal that is transmitted back from the control circuit to the battery management system

[0102] HV high voltage potential (HV: High voltage)

[0103] IPYRO triggering current «2A to trigger the pyro fuse IBAT battery current

[0104] ILADE Charging current for charging the capacitor

[0105] ITEST test current «100mA for testing the pyro-fuse without triggering the pyro-fuse

[0106] LV Low voltage potential (LV: Low voltage)

[0107] ULADE Charging voltage for charging the capacitor UMESS Voltage drop across the current measuring resistor for measuring the battery current

[0108] Uv supply voltage for charging the capacitor

Claims

CLAIMS 1. Pyrotechnic battery separation system (1), in particular for a motor vehicle electrical system of a battery-electric car or a hybrid car, comprising a) an electric high-voltage battery (2) with a low side at low-voltage potential (LV) and a high side at high-voltage potential (HV), in particular with a battery voltage of at least 60 V, 200 V, 400 V, 600 V or 800 V, b) a pyro-fuse (4) for electrically separating the high-voltage battery (2), wherein the pyro-fuse (4) is connected in series with the high-voltage battery (2) and arranged on the high side of the high-voltage battery (2) so that the pyro-fuse (4) is at the high-voltage potential (HV), and c) a control circuit (7) with a trigger output for triggering the pyro-fuse (4), wherein the pyro-fuse (4) disconnects the high-voltage battery (2) when triggered, characterized in thatd) that the control circuit (7) is also arranged on the high side of the high-voltage battery (2) and is at the high-voltage potential (HV) in order to avoid a brief short circuit between the high-voltage potential (HV) of the pyro-fuse (4) and the low-voltage potential (LV) when the pyro-fuse (4) is triggered.

2. Pyrotechnic battery separation system (1) according to claim 1, characterized by a) an electrical energy store (10) for providing the electrical energy for triggering the pyro-fuse (4), and b) a controllable first switching element (11) for electrically connecting the electrical energy store (10) to the pyro-fuse (4) for triggering the pyro-fuse (4), wherein the first switching element is controllable via the trigger output of the control circuit (7).

3. Pyrotechnic battery separation system (1) according to claim 2, characterized in that a) the control circuit (7) controls the first switching element (11) for triggering the pyro-fuse (4) in such a way that the energy storage device (10) is connected to the pyro-fuse (4) for a specific triggering duration, wherein a specific triggering current (IPYRO) flows through the pyro-fuse (4) during the triggering duration, b) the triggering current (IPYRO) and the triggering duration together are sufficiently large to Pyro-fuse (4), c) that the tripping current (IPYRO) is preferably at least 500 mA, 1 A or 2 A, and d) that the tripping duration is preferably at least 500 s, 1 ms, 2 ms or 4 ms.

4. Pyrotechnic battery separation system (1) according to claim 2 or 3, characterized in that a) the electrical energy store (10) has a capacitor, in particular a double-layer capacitor or a supercapacitor, and / or b) the controllable first switching element (11) has a power transistor, in particular a MOSFET, and / or c) the control circuit (7) is an integrated circuit.

5. Pyrotechnic battery separation system (1) according to one of claims 2 to 4, characterized in that a) a current limiter is arranged between the electrical energy store (10) and the pyro-fuse (4) in order to limit the triggering current (IPYRO) to a maximum value and thereby to keep the triggering current (IPYRO) as constant as possible during the triggering period, b) the maximum value of the triggering current (IPYRO) predetermined by the current limiter is preferably at most 5 A, 3 A or 2 A, c) the triggering current (IPYRO) is preferably essentially constant between the switching edges during the triggering period and only has fluctuations of less than 50%, 30%, 20%, 10% or less than 5%, d) the current limiter preferably has a constant current source.

6. Pyrotechnic battery separation system (1) according to one of claims 2 to 5, characterized in that a) a transformer (16) is provided for charging the electrical energy store (10), b) the transformer (16) receives a supply voltage (Uv) on the input side, in particular an on-board network voltage of +12 V, c) the transformer (16) is connected on the output side to the energy store (10) and supplies the energy store (10) with a charging voltage (ULADE), in particular a charging voltage of at least +20 V, +30 V or +48 V, and d) the charging voltage (ULADE) is greater than the supply voltage (Uv).

7. Pyrotechnic battery separation system (1) according to one of the preceding claims, characterized in that a) a first current sensor (8) is provided which measures a battery current (IBAT) of the high-voltage battery (2), b) the control circuit (7) has a first measuring input (9) which is connected to the first current sensor (8) in order to detect the battery current (IBAT), and c) the control circuit (7) triggers the pyro-fuse (4) if an evaluation of the measured battery current (IBAT) indicates an overcurrent, in particular if the measured battery current (IBAT) exceeds a predetermined maximum value.

8. Pyrotechnic battery separation system (1) according to claim 7, characterized in that a) the first current sensor (8) is arranged on the high side of the high-voltage battery (2), and / or b) the first current sensor (8) has a first low-resistance current measuring resistor (8) which is connected in series with the high-voltage battery (2) so that the battery current (IBAT) also flows through the first low-resistance current measuring resistor (8), and / or c) the control circuit (7) measures a voltage drop (UMESS) across the first low-resistance current measuring resistor (8) as a measure of the battery current (IBAT) via the first measuring input (9), and / or d) the first low-resistance current measuring resistor (8) has a resistance value of less than 100 mΩ, 50 mΩ, 10 mΩ, 5 mΩ, 1 mΩ, 500 pΩ, 250 pΩ or 100 pQ.

9. Pyrotechnic battery separation system (1) according to one of the preceding claims, characterized in that a) the control circuit (7) has a test output (17) to test the pyro-fuse (4) during a test process without triggering the pyro-fuse (4), and / or b) the control circuit (7) drives a test current (ITEST) through the pyro-fuse (4) via the test output (17) during the test process, wherein the test current (ITEST) is SO small that it is not sufficient to trigger the pyro-fuse (4), and / or c) a second current sensor is provided to measure the test current (ITEST), and / or d) the control circuit (7) has a second measuring input (20) which is connected to the second current sensor (18) to detect the test current (ITEST), and / or e) the test output (17) of the control circuit (7) is a digital output, and / or f) the Test current (ITEST) is less than 1 A, 500 mA, 250 mA or 100 mA,and / or g) that the second current sensor (18) has a second current measuring resistor (18) which, is arranged between the test output of the control circuit (7) and the pyro-fuse (4) and is passed through by the test current (ITEST) during the test process, wherein the second measuring input (20) of the control circuit (7) measures a voltage drop across the second current measuring resistor as a measure of the test current (ITEST), and / or h) that a series resistor is connected in series with the second current measuring resistor to limit the test current (ITEST), and / or i) that the second current measuring resistor (18) is preferably low-ohmic, and / or j) that the second low-ohmic current measuring resistor (18) has a resistance value of less than 100 mQ, 50 mQ, 10 mQ, 5 mQ, 1 mQ, 500 pQ, 250 pQ or 100 pQ.

10. Pyrotechnic battery separation system (1) according to one of the preceding claims, characterized in that a) the control circuit (7) has an interface connection (21) for receiving a crash signal (25) for triggering the pyro-fuse (4) in the event of a crash, in particular from a battery management system (23) which is connected to a crash sensor, b) a potential separation element (22) is preferably connected to the interface connection (21) of the control circuit (7) in order to decouple the control circuit (7) which is at the high-voltage potential (HV) from the crash signal from the low-voltage range (6).

11. Pyrotechnic battery separation system (1) according to claim 10, characterized in that a) that the interface connection (21) of the control circuit (7) also enables the reception of a diagnostic signal (24) and the retransmission of the diagnostic signal (27), b) that the diagnostic signal (24) preferably differs from the crash signal (25), so that the control circuit (7) can distinguish the diagnostic signal (24) from the crash signal (25) and does not trigger the pyro-fuse (4) when the diagnostic signal (24) is received, c) that the diagnostic signal (24) preferably has a different signal level or a different signal shape than the crash signal (25), in particular a lower level.

12. Pyrotechnic battery separation system (1) according to 10 or 11, characterized in that a) that the potential separation element (22) enables a bidirectional data transmission, namely in a first transmission channel a data transmission to the control circuit (7) and in a second transmission channel a data transmission from the control circuit (7), b) that the two transmission channels of the potential separation element (22) to the control circuit (7) and are jointly connected to the interface connection (21) of the control circuit (7), c) that the two transmission channels of the potential separation element (22) run externally separately from one another, d) that the data transmission in the two transmission channels is preferably analogue.

13. Pyrotechnic battery separation system (1) according to one of the preceding claims, characterized in that a) a controllable second switching element (15) is provided for connecting the transformer (16) to the electrical energy store (10), b) the control circuit (7) has a charging control output (14) which controls the second control element (15), and c) the control circuit (7) has a third measuring input (13) which is connected to the energy store (10) in order to measure the charging voltage (ULADE) at the energy store (10).

14. Pyrotechnic battery separation system (1) according to one of the preceding claims, characterized in that a) the control circuit (7) has a first analog / digital converter at the first measuring input (9), which converts an analog external measured value of the electrical voltage drop across the first low-ohm current measuring resistor (8) into a corresponding internal digital value, and / or b) the control circuit (7) has a second analog / digital converter at the second measuring input (20), which converts an analog external measured value of the electrical voltage drop across the second current measuring resistor into a corresponding internal digital value, and / or c) the control circuit (7) has a third analog / digital converter at the third measuring input (13), which converts an analog external measured value of the charging voltage into a corresponding internal digital value,and / or d) that the control circuit (7) has a fourth analog / digital converter at the interface connection (21) which converts the crash signal or the diagnostic signal received from outside into a corresponding digital value., 15. Pyrotechnic battery separation system (1) according to one of the preceding claims, characterized in that a) that the control circuit (7) triggers the pyro-fuse (4) in the event of a crash and / or b) that the control circuit (7) triggers the pyro-fuse (4) in the event of an overcurrent.

16. Pyrotechnic battery separation system (1) according to one of the preceding claims, characterized in that the following components are integrated in a common assembly, in particular in a common housing: a) the first current sensor (8) for measuring the battery current (IBAT), b) the control circuit (7) for triggering the pyro-fuse (4), c) the energy storage device (10) for providing the energy to trigger the pyro-fuse (4), d) the second current sensor (18) for measuring the test current (ITEST), e) the transformer (16) for providing the charging voltage (ULADE) for the energy storage device (10), f) the potential separation element (22), g) the first switching element (11) for connecting the energy storage device (10) to the pyro-fuse (4), h) the diode (19), i) the series resistor for limiting the test current (ITEST), j) the current limiter for limiting the trigger current (IPYRO), k) the second switching element (15) for connecting the energy storage device (10) to the transformer (16),and / or l) a microcontroller for communication with the control circuit (7)., 17. Motor vehicle electrical system with a pyrotechnic battery separation system (1) according to one of the preceding claims.

18. Motor vehicle, in particular a battery-electric car or hybrid car, with a motor vehicle electrical system according to claim 17.

19. Operating method for a pyrotechnic battery separation system (1) with a high-voltage battery (2) with a high-side and a low-side and with a pyro-fuse (4) for separating the high-voltage battery (2), wherein the pyro-fuse (4) is arranged in a high-voltage area (5) on the high-side of the high-voltage battery (2), in particular for a pyrotechnic battery separation system (1) according to one of claims 1 to 15, with the following step: a) controlling the pyro-fuse (4) with a triggering current (IPYRO) from a control circuit (7) for triggering the pyro-fuse (4), characterized in that b) that the control circuit (7) is also arranged on the high side of the high-voltage battery (2) and is at the high-voltage potential (HV) in order to avoid a brief short circuit between the high-voltage potential (HV) of the pyro-fuse (4) and the low-voltage potential (LV) when the pyro-fuse (4) is triggered.

20. Operating method according to claim 19, characterized by the following steps (S5) for diagnosing the control circuit (7): a) transmitting a diagnostic signal (24) from externally to the control circuit (7), in particular from a battery management system (23), and b) retransmitting the diagnostic signal (27) from the control circuit (7) externally, in particular to the battery management system (23), to indicate correct functioning of the control circuit (7).

21. Operating method according to claim 19 or 20, characterized by the following steps (S1-S3) for testing the pyro-fuse (4) by the control circuit (7): a) driving a test current (ITEST) through the pyro-fuse (4) from the control circuit (7), wherein the test current (ITEST) is SO small that it is not sufficient to trigger the pyro-fuse (4), b) measuring the test current (ITEST) by means of the second current sensor (18), and c) evaluating the measured test current (ITEST) by the control circuit (7) to assess the functionality of the pyro-fuse (4).

22. Operating method according to one of claims 19 to 21, characterized by the following steps (S8-S12) for triggering the pyro-fuse (4): a) measuring the battery current (IBAT) by means of the first current sensor (8), b) evaluating the measured battery current (IBAT) in the control circuit (7) to detect an overcurrent, c) triggering the pyro-fuse (4) by the control circuit (7) in the event of an overcurrent, and / or d) receiving a crash signal (25) by the control circuit (7) and triggering the pyro-fuse (4) by the control circuit (7) when the crash signal (25) is received.

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