VEHICLE INCLUDING A TRACTION BATTERY DISCONNECT SYSTEM VIA A PASSIVE SAFETY CONTROL UNIT

Abstract

An electric or hybrid motor vehicle comprising a traction battery (2) equipped with at least one isolation relay (R1) capable of electrically isolating the traction battery from the rest of the vehicle by interrupting the power line, a passive safety control unit (1) coupled to acceleration sensors (11), and configured to activate a plurality of occupant protection devices in the event of a collision, including an electrical safety output (61), a battery management computer (5) comprising an electrical safety input (62), electrically connected to the electrical safety output, the isolation relay being controlled by the battery management computer (5), configured to react without delay to an activation of the electrical safety input (62), by generating a command to open the isolation relay. Figure 2

Description

Title of the invention: VEHICLE COMPRISING A VIA TRACTION BATTERY DISCONNECTION SYSTEM A PASSIVE SAFETY CONTROL UNIT

[0001] The invention relates to the field of traction battery isolation systems in an electric or hybrid vehicle. The invention concerns a vehicle comprising a traction battery disconnection system in the event of a collision via a passive safety control unit.

[0002] It should be noted from the outset that the passive safety control unit is referred to in practice in the trade as the "airbag computer".

[0003] Such a disconnection system can be used, for example, in the case of protecting occupants or responders following an accident involving the vehicle.

[0004] It should be noted that such a disconnection system (also called an isolation system) also makes it possible to avoid delivering and circulating electrical power in circumstances which make this problematic, either for the equipment or for the personnel involved.

[0005] In the event of an accident involving the vehicle, it is very difficult, and in practice impossible, to predict the damage sustained by the vehicle's structure, and in particular the precise temporal sequence of the occurrence of this damage. The diversity of possible impact configurations and intensities is virtually unlimited.

[0006] Known configurations are known where the passive safety control unit activates a pyrotechnically tripped fuse intended to interrupt the positive power line, and where appropriate another pyrotechnically tripped fuse intended to interrupt the negative power line.

[0007] However, if the traction battery has not been mechanically damaged, the need to replace the pyrotechnically triggered fuse(s) necessitates providing access to the inside of the battery pack, which is undesirable from a battery pack design perspective. This also implies a significant repair time, in addition to the substantial cost of the replacement part.

[0008] It should be noted that the pyrotechnic trip fuse is a single-use element, which must be replaced after tripping.

[0009] According to another possible configuration, the active passive safety control unit transmits a crash information message to the battery management computer, which then interrupts the power supply lines from the traction battery. This process takes several tens of milliseconds, in practice about a hundred ms, and this delay proves in practice to be too long and it is possible that the crash information will not be received or that the shutdown action will not be executed correctly.

[0010] Furthermore, it is desirable to be able to trigger the opening of the relays outside of short-circuit conditions, that is, before mechanical damage can lead to a situation where the current flowing through the relays is much higher than the maximum rated current. Indeed, if a very high current flows through the relay contact when an attempt is made to trigger it, there is no guarantee that the contact will open; it may remain stuck.

[0011] It is in this context that the inventors sought to propose a solution that is not very intrusive in the battery pack and that also makes it possible to reduce the response time between the start of the shock and the effective opening of the relays.

[0012] To achieve this objective, the invention proposes, in its broadest sense, an electric or hybrid motor vehicle, comprising a traction battery equipped with at least one isolation relay capable of electrically isolating the traction battery from the rest of the vehicle by interrupting at least the positive power line, a passive safety control unit coupled to at least acceleration sensors, and configured to activate a plurality of occupant protection devices in the event of a collision, including an electrical safety output, a battery management computer comprising an electrical safety input, electrically connected to the electrical safety output, characterized in that the isolation relay is controlled by the battery management computer, configured to react without delay to an activation of the electrical safety input,by generating a command to open the isolation relay.

[0013] Thanks to the provisions described above, the opening of the isolation relay can occur less than 40 ms after the start of the crash, and preferably less than 30 ms after the start of the crash. Thus, the opening of the relay occurs before the occurrence of structural damage that could cause short circuits or power line outages.

[0014] In particular, the opening of the relay (or relays if there are two) occurs before any significant mechanical damage may occur in the vehicle's powertrain.

[0015] Advantageously, the entity responsible for activating and deploying the occupant protection means also simultaneously generates an electrical signal leading to the opening of the isolation relay (or both isolation relays when there are two). There is no delay in information transmission or processing in another entity.

[0016] Advantageously, the opening of the isolation relay takes place at nominal current and it is not necessary to provide for the ability to open the relay at much higher currents such as short-circuit currents, because in fact the opening is carried out before one or more short circuits can occur.

[0017] It must be understood that the battery management computer software does not intervene, in this circumstance, in the process of interrupting the power lines connected to the high-voltage battery.

[0018] Indeed, the processing carried out inside the battery management computer is essentially hardware, i.e. hardware, there is no software loop involved in the proposed process.

[0019] It should be noted that the term "isolation relay" covers any device acting as an isolation contactor, that is to say, a device which can be selectively controlled by an electrical signal, in a reversible manner, either to an electrically open state or to an electrically closed state.

[0020] The term "rest of the vehicle" should be understood to mean all vehicle components other than the battery.

[0021] It should be noted that the positive power line is connected to the positive terminal of the traction battery. The negative power line is connected to the negative terminal and can be connected to the vehicle ground, as in the case of some mild hybrid vehicles, or can be floating in the case of higher battery voltages with two relays, as will be seen below.

[0022] The single isolation relay configuration corresponds to a hybrid vehicle configuration, for example with a traction battery with a nominal voltage of 48 volts. We will see two-relay configurations for higher voltages later.

[0023] A passive occupant protection system is commonly called an airbag system. Such a passive safety system includes one or more acceleration and / or deceleration sensors and is capable of determining, with ultra-fast precision, the intensity and nature of the impact (frontal impact, side impact, rear impact, rollover, etc.). Based on this knowledge of the impact, the passive safety system can determine the severity of the impact and, if necessary, trigger the deployment of protective devices and the electrical safety shutdown.

[0024] It should be noted that the isolation relays in question here are used, on the one hand, to normally isolate the high-voltage battery from the rest of the vehicle and, on the other hand, in the event of a crash, to urgently isolate the high-voltage battery. There is no specific relay for performing the emergency disconnection in the event of a crash.

[0025] Regarding the vocabulary related to switches in this document, a "high side" switch corresponds to a control on the side of a positive polarity and a "low side" switch corresponds to a control on the side of a negative polarity; these terms "high side" and "low side" have been established by industry practice for a very long time.

[0026] Also with regard to vocabulary, the term "hardware" has become established in the practice of the trade to designate the equipment.

[0027] According to an option useful particularly in the case of 100% electric vehicles, the traction battery is equipped with two isolation relays capable of electrically isolating the traction battery by interrupting respectively the positive and negative power lines, the vehicle being characterized in that the two isolation relays are controlled by the battery management computer (5), configured to react without delay to an activation of the electrical safety input, by generating a command to open the two isolation relays.

[0028] Both high-voltage power lines are interrupted, i.e. not only the positive line as before, but also the negative line which is not connected to the vehicle ground (it is floating with respect to ground).

[0029] According to one embodiment, the battery management computer includes at least one crash interface circuit and a relay control link circuit which performs a logical AND between a functional command issued by the battery management computer and a cut-off command from the crash interface circuit.

[0030] Wherefore, the interruption of the relay control by the hardware circuitry connected to the electrical safety input from the airbag control unit is compatible with the normal functional relay control emanating from the battery management control unit.

[0031] When the battery management computer commands the opening of both relays, two separate relay control link circuits are provided. In contrast, the crash interface circuit can be common to both relay commands.

[0032] In one embodiment, the crash interface circuit is a hardware circuit. In one embodiment, the relay control link circuit is a hardware circuit. The response times of these circuits are substantially less than 1 ms; they simply involve electronic gate switching.

[0033] According to one embodiment, the crash interface circuit includes a load resistor equivalent to the apparent resistance of a pyrotechnically tripped fuse. Consequently, it is not necessary to make modifications to the standard airbag control unit, thus saving on requalification costs. airbag control unit even though the use of the pyrotechnic fuse output is cleverly diverted.

[0034] Said load resistance can be chosen between 1 ohm and 2 ohms, for example 1.5 ohm.

[0035] According to an advantageous option, the coil of the relay or of each of the two relays is controlled on both sides, positive and negative, by the battery management computer.

[0036] In practice, the coil of each of the two relays is controlled on one positive side by high-side switches of the battery management computer and on one negative side by low-side switches of the battery management computer. This allows for two-level control, for reasons of operational safety or for diagnostic purposes.

[0037] According to one embodiment, the relay or both relays are normally open type relays.

[0038] Consequently, the rest position of the relay corresponds to an open electrical state, and therefore to an interruption of the high-voltage power lines. In the event of an unexpected interruption of the power supply, both isolation relays will then open.

[0039] According to one embodiment, the vehicle includes a service battery, configured to electrically power the passive safety control unit and the battery management computer. The service battery is generally smaller and less exposed than the traction battery to damage as a result of an impact. Both computers involved continue to be powered normally at least during the initial phase of the impact.

[0040] According to one embodiment, the nominal voltage of the auxiliary battery is conventional, for example 12 volts.

[0041] According to one embodiment, the TP activation switch inside the airbag control unit can be a MOSFET type transistor, e.g. a PNP transistor.

[0042] According to one embodiment, the positive power line and the negative power line are without pyrotechnically tripped fuses.

[0043] Wherefore, the proposed solution is simple, effective and inexpensive, while in practice it offers the function performed by the pyrotechnic device present in known configurations of the art.

[0044] According to one embodiment, a thermal trip fuse is also provided, either on the positive or negative power line. The function of the thermal fuse (which trips irreversibly) is different from and complementary to the function of the isolation relays. The two devices coexist in the same power circuit.

[0045] According to one embodiment, the battery management computer is configured to control the two isolation relays with a time offset of a few tens or hundreds of milliseconds.

[0046] For the relay bonding process, this allows for a pre-charging function of the capacitive loads. One of the two relays is bonded, and the other relay is supplemented in parallel by a series resistor pre-charging circuit. The second relay is then bonded after a few hundred milliseconds, once the capacitive loads have been energized.

[0047] For the opening of the relays, a small time delay can also be applied to alternate the effect of the current interruption on the spark; it is the relay that is opened first that interrupts the current and undergoes the arc, and the other relay, opened after, with zero current, is preserved.

[0048] According to one embodiment, the passive safety control unit is configured to also transmit to the battery management computer at least one piece of information concerning the triggering of an emergency opening of the control power supply line. This information is transmitted via a digital network, e.g., a CAN bus or similar.

[0049] Whereupon, the battery management computer is informed of the occurrence of a crash so as to refrain from ordering the activation of the isolation relays again.

[0050] According to an alternative or complementary embodiment, the battery management computer may include a replay line of the crash interface circuit, read by its microcontroller, so as to be informed of the occurrence of a shock and consequently to refrain from ordering the activation of the isolation relays again.

[0051] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which:

[0052] [Fig-1] schematically illustrates a side view of an electric vehicle in in which a battery isolation system according to the present invention is implemented; [Fig.2] shows a schematic electrical diagram of a part of an electric or hybrid vehicle illustrating the present invention; [Fig.3] shows a schematic electrical diagram of specific circuits planned in the battery management computer; [Fig.4] shows an example of a timing diagram illustrating the control of the isolation relays in a nominal case and in the case of the occurrence of a shock; [Fig.5] is analogous to [Fig.2], and shows a simplified case of a single isolation relay configuration; [Fig.6] is analogous to [Fig.2], and shows a variant case of a configuration where the crash cutoff command attacks the high-side switches.

[0053] In the various figures, the same reference numerals designate identical or similar elements. For the sake of clarity, some elements are not necessarily shown to scale, particularly concerning the timings and time intervals of the chronograms.

[0054] We are interested here in an electric or hybrid vehicle with an electric drivetrain.

[0055] With regard to the location of the vehicle in space, the X direction corresponds to the longitudinal direction of the vehicle, the Z direction corresponds to the vertical direction with respect to the local ground and the Y direction perpendicular to the two previous ones and corresponds to the transverse direction of the vehicle.

[0056] In an electric motor vehicle 9, there is a traction battery 2 designed to store a significant amount of electrical energy in electrochemical form. The traction battery is an electrical energy storage device, more concisely called an 'electric battery' or even a 'battery', and a 'battery pack' when including the mechanical protection and electrical protection components discussed in this document.

[0057] Regarding the amount of energy stored in the battery pack, in practice we are talking about several tens of kWh. A 100% electric vehicle battery typically has an energy storage capacity between 50 kWh and 100 kWh, depending on the target range, weight, and consumption of the vehicle, and slightly less for a plug-in hybrid vehicle. Battery 2 is recharged using a charging base 94, as is known per se.

[0058] In the case of mild hybrid vehicles, the traction battery voltage may be lower, e.g. 48 V, with its negative terminal connected to the vehicle chassis; this case will be illustrated with reference to [Fig. 5] at the end of this description.

[0059] The most common traction batteries for electric vehicles are lithium-ion type batteries, although other types of electrochemistry are not excluded. A battery pack generally consists of several modules connected together in a series configuration, each module itself comprising a plurality of individual electrochemical cells, arranged in series and / or in parallel.

[0060] The battery pack has a fairly high voltage across its terminals (B+, B-), in practice exceeding 100 volts, most often between 200 volts and 800 volts. Voltages exceeding 800 volts are also possible.

[0061] The voltage of this type of battery thus extends beyond the extra-low voltage (ELV) range, and it is necessary to take precautions; indeed, there are regulatory protection requirements, particularly with regard to possible contacts induced by an operator's action (e.g., a rescue worker) either with bare hands or with the aid of a tool, or any other unwanted contact following a mechanical shock suffered (in the case of a 'crash').

[0062] The occupant protection system includes airbags. Among the airbags shown in [Fig. 1], there is a driver's front airbag 33 arranged in the steering wheel 95 and a front airbag for the front passenger. In addition, there are side airbags 32 and so-called 'curtain' side head airbags 34. An occupant protection system also includes seat belt pretensioners 31 which lock the retractors and eliminate any slack in the seat belts on the occupants' bodies. The inclusion of other known inflatable protection devices is not excluded.

[0063] The occupant protection system includes a passive safety control unit 1, also called the "Airbag computer". This computer is usually positioned near the nominal center of gravity of the vehicle.

[0064] The occupant protection system includes acceleration sensors 11, also called accelerometers or shock sensors. The airbag control unit filters the information provided by the accelerometers.

[0065] The passive safety control unit 1 comprises a microcontroller 10, an entity known per se and therefore not described in detail here. The passive safety control unit 1 is powered by an input 14 from the ordinary 12-volt onboard network and also includes a reservoir 16, which provides the passive safety control unit with sufficient autonomy to operate for a certain time even if the incident power supply 14 is lost during a crash. This time is sufficient to activate, if necessary, all the igniters 12 of the occupant protection devices. In this case, the reservoir 16 is also used to interrupt the power lines connected to the traction battery 2, as will be seen below.

[0066] The airbag control unit 1 also includes a special output, usually used to trigger a pyrotechnical fuse. This special output is advantageously used in the present invention to transmit the triggering information to the battery management control unit 5, given that the electrical distribution system, and in particular the high-voltage (HV) network, does not have a pyrotechnical fuse.

[0067] The particular output uses a TP switch and two terminals collectively marked 61. This particular output is referred to here as the electrical safety output.

[0068] These two terminals are connected respectively to two inputs of the battery management computer via a first conductor 81 and a second conductor 82.

[0069] The TP activation switch inside the airbag control unit can be a MOSFET type transistor, e.g. a PNP transistor, it can be associated with a current-regulated control, including a current sensor or equivalent.

[0070] Indeed, the current flowing through conductors 81 and 82 when the output is activated must be above a predetermined threshold. Conversely, for diagnostic purposes, the airbag control unit injects current into conductors 81 and 82 at lower current values, e.g., below another predetermined threshold, to remain within the non-activation range of the output.

[0071] In the battery management computer 5, there is provided an electrical safety input marked 62 and connected (also said to be linked) electrically to the electrical safety output 61 by conductors 81 and 82.

[0072] In the battery management computer 5, a crash interface circuit 55 is provided.

[0073] This crash interface circuit 55 is described in more detail with the help of [Fig.3] below.

[0074] The vehicle's electrical system includes a high-voltage network, which supplies in particular the inverter(s) of the electric traction motors as well as a DC / DC converter (not shown) which allows a second low-voltage on-board network to be cascaded, here for example a 12-volt network, which includes a 12-volt battery identified as 6 and illustrated in [Fig.2].

[0075] The battery pack 2 is associated with a battery management computer 5, commonly referred to in English as BMS (Battery Management System) or BMU (Battery Management Unit).

[0076] The battery management computer 5 is connected to a plurality of temperature sensors arranged in the modules that make up the battery via conductors 52 which connect the battery 2 to the computer 5. It should be noted that the interface between the battery and the battery management computer can be more complete and more complex, with additional functions not detailed here.

[0077] The battery management computer 5 includes a microcontroller 50, an entity known in itself and therefore not described here in detail.

[0078] The battery pack further includes two isolation relays RI, R2.

[0079] The two isolation relays are capable of electrically isolating the battery from the rest of the vehicle, i.e. the first relay RI is capable of interrupting the positive power line 41, and the second relay R2 is capable of interrupting the negative power line 42, which is floating with respect to the vehicle chassis.

[0080] These RI, R2 relays are power relays; their contacts can withstand a continuous current of several hundred amperes, and up to 1500 amperes peak. These power relays have a rated breaking capacity of at least several hundred amperes under load, and of more than 1000 amperes at least once.

[0081] On the control side, the first relay RI comprises a coil marked BB1, and the second relay R2 comprises a coil marked BB2. Both relays are normally open. As is known, current must flow through the coil to close the contact. Conversely, if no current flows through the coil, the relay contact is returned to the open state by an elastic element such as a spring.

[0082] When both relays RI, R2 are open, there is no longer any voltage on the downstream HV+ and HV- power lines, identified as 41a and 42a in [Fig. 1]. Under this condition, a potential electrical risk related to the high voltage HV in the rest of the vehicle is avoided.

[0083] In an alternative not shown in the figures, it would be possible to use a single relay with two insulated contacts to simultaneously interrupt the positive power line and the negative power line

[0084] The positive power line 41 is coupled to the positive terminal B+ of the battery 2 and the negative power line 42 is coupled to the negative terminal B-.

[0085] The electrical conductors forming these power lines and carrying the currents delivered by the battery can be metal busbars or large-section cables. As already mentioned in the introduction, the voltage between the two power lines is several hundred volts, for example 400 volts in a typical example.

[0086] In addition, a conventional thermally tripped fuse 21 is provided, here arranged on the positive power line 4L. It is understood that this fuse could be positioned on the negative power line. The rating of this thermal fuse 21 is several hundred amperes, for example, 500 amperes.

[0087] It should be noted that the positive power line or the negative power line may be equipped with a current sensor, not shown in [Fig.2], for example in this case a shunt across which a voltage drop is measured.

[0088] Optionally according to the present invention, the airbag control unit 1 transmits to the battery management control unit 5 non-binary information concerning the occurrence of a shock suffered by the vehicle.

[0089] For this purpose, the battery management control unit 5 and the airbag control unit are intended to communicate via a multiplexed network 92, for example a CAN-type network. There is no wired electrical connection specifically linking the airbag control unit and the battery management control unit.

[0090] In the illustrated example, the battery management computer 5 is connected to a first CAN network 92, and the airbag computer is connected to a second CAN network, the first and second CAN networks being linked together by a computer 91 acting as a bridge / gateway, which can be the general body control computer (Body Controller) or a powertrain management computer (with or without internal combustion engine).

[0091] Crash interface circuit and relay control link circuit

[0092] As can be seen in Figures 2 and 3, the crash interface circuit identified as 55 receives a input an electrical current supplied by the electrical safety control driver TP located inside the airbag computer 1, via conductors 81,82.

[0093] Inside the crash stage interface circuit arranged a load resistor R5.

[0094] Said load resistor R5 has a value equivalent to the apparent resistance of a pyrotechnical fuse. Cleverly, this allows the airbag control unit to be tricked into seeing either a pyrotechnical fuse or the input stage proposed in the present invention within the battery management control unit.

[0095] According to one option, said load resistance is chosen between 1 ohm and 2 ohms, for example 1.5 ohm.

[0096] The positive terminal of the load resistor R5 is connected to a positive input 76 of a comparator 7 via an adaptation stage R6,C1. The comparator 7 can be, for example, an operational amplifier or any other equivalent comparator.

[0097] The negative input 77 of the comparator is connected to a reference voltage denoted Vref.

[0098] The comparator output 78 is connected to an 'In' input of a memory flip-flop 4, which is known in itself and therefore not described in detail here.

[0099] The stored output of the flip-flop passes through an inverter gate marked 75.

[0100] After this inversion, the output of the crash interface circuit is noted 85 and this output is directed to an input of an AND gate noted 3 forming part of the relay control link circuit 56 arranged downstream of the crash interface circuit 55.

[0101] The normal functional control of the relay coil is represented by the line labeled 84, which is connected to a first input 37 of the AND gate. Furthermore, the output of the crash interface circuit 85 is connected to a second input 36 of the AND gate.

[0102] Output 38 of the AND gate constitutes the command to be injected onto the negative terminal of coil BB1 of relay RL

[0103] As seen in [Fig. 2], when there are two relays R1, R2 to be controlled, the relay control link circuit 56 is duplicated; there is a second equivalent circuit to control the coil BB2 of the second relay R2. This second circuit uses the same signal 85 from the crash interface circuit output. In the normal situation, outside of an accident, the comparator output is in the BAT state on the pull-down resistor R7, and line 85 remains in logic state 1. If the airbag control unit happens to trigger its electrical safety output 61, the comparator output 78 switches to the high state and line 85 switches to logic state 0, which closes the AND gate.

[0104] Relay coil control

[0105] The control supply line 67 for the control of relays RI and R2 comes from the positive terminal 60 of the 12-volt battery 6. The positive terminal 60 of the 12-volt battery 6 also serves, via input 54, to supply the general electronic circuits of the battery management computer.

[0106] A fuse 71 and possibly an interruptible portion operable by a voluntary manual action of a professional operator may be provided on the control supply line 67.

[0107] Inside the battery management computer 5, the control supply line of the first relay passes through an auxiliary electronic switch T1H and then exits the battery management computer to go, according to the third line segment 63, to one of the terminals of the coil of the relay RI, marked BB1. The other terminal of the coil BB1 is connected by a fourth segment 64 to a main activation switch T IL configured to pull to ground.

[0108] The switches T1H and T2H are P-channel MOSFETs or PNP-type transistors. For MOSFETs, the hot end is called the Source and the cold end is called the Drain.

[0109] The switches T1L and T2L are N-channel MOSFETs or NPN transistors. For MOSFETs, the hot end is called the Drain and the cold end is called the Source.

[0110] The control supply line of the second relay R2 has a first common part with the control supply line of the first relay.

[0111] Inside the battery management computer 5, the control supply line for the second relay passes through a second auxiliary electronic switch T2H and then exits the battery management computer to go, according to the third line segment 65, to one of the terminals of the relay coil R2, labeled BB2. The other terminal of the coil BB2 is connected by a fourth segment 66 to a second main activation switch T2L configured to pull to ground.

[0112] The grids or bases of the switches T1H, T1L, T2H, T2L are generally controlled by the microcontroller 50 of the battery management computer 5, with additional intervention according to an advantageous feature of the present invention of a hardware crash interface circuit.

[0113] Turning towards [Fig.4], the x-axis carries time and the y-axis carries the LogST logic states, a high state representing an active state (or a passing state in the case of a switch).

[0114] With reference to [Fig. 4], the first part of the timing diagram illustrates at time t1 a typical closure of the relays initiated by the battery management computer 5, for example when the vehicle is switched on. Line 85 is in logic state 1 (non-crash situation).

[0115] At time tl, switches T1L and T2L are activated, and switches T1H and T2H are activated, the contacts of relays R1, R2 close.

[0116] The second part of the chronogram illustrates a shock situation, for which line 85 switches to the low state (see above) and gates ET 3 close.

[0117] At time t2, the switches T1L, T2L are deactivated, and at time t3 the contacts of the relays R1, R2 open and the isolation of the traction battery is thus obtained.

[0118] The time interval d2, the reaction time between t2 and t3, is in practice between 10 milliseconds and 20 ms. A total response time between the start of the shock and the opening of the relays is obtained that is less than 30 ms.

[0119] The battery management computer 5 and the airbag computer 1 are both powered by the low voltage network 8 to 12 volts, i.e. powered by the 12 volt battery 6 independently of the state of the two isolation relays RI, R2.

[0120] Early interruption of the high voltage HV network by opening relays RI and R2 has no short-term effect on the supply provided by the 12-volt battery 6.

[0121] Single-relay lightweight hybridization configuration ([Fig.5]).

[0122] In these mild hybrid configurations, e.g., with a voltage below 60 Volts, the negative terminal B- of the HV BATT battery is connected to the chassis. Therefore, the second relay is no longer present, and the negative power line is directly connected to ground, i.e., to the vehicle chassis.

[0123] Opening the first RI relay is sufficient to eliminate any problematic voltage from the downstream user HV network.

[0124] The control of the first RI relay remains identical to that described in relation to [Fig. 2]. The operating logic is identical or similar, mutatis mutandis, to that already described previously.

[0125] High side command configuration ([Fig.6]).

[0126] According to an alternative solution, the crash interface circuit can act not on the low-side switches but on the high-side switches, as shown in [Fig. 6]. The operating logic is identical or similar, mutatis mutandis, to that already described previously in relation to [Fig. 2] and [Fig. 3].

Claims

Demands

1. Electric or hybrid motor vehicle, comprising a traction battery (2) equipped with at least one isolation relay (IR) capable of electrically isolating the traction battery from the rest of the vehicle by interrupting at least the positive power line (41), a passive safety control unit (1) coupled to at least acceleration sensors (11), and configured to activate a plurality of occupant protection devices in the event of a collision, including an electrical safety output (61), a battery management computer (5, BMS) comprising an electrical safety input (62), electrically connected to the electrical safety output, characterized in that the isolation relay (IR) is controlled by the battery management computer (5), configured to react without delay to an activation of the electrical safety input (62),by generating a command to open the isolation relay.

2. Motor vehicle according to claim 1, wherein the traction battery is equipped with two isolation relays (R1,R2) capable of electrically isolating the traction battery by interrupting respectively the positive (41) and negative (42) power lines, characterized in that the two isolation relays are controlled by the battery management computer (5), configured to react without delay to an activation of the electrical safety input, by generating a command to open the two isolation relays.

3. Motor vehicle according to any one of claims 1 to 2, wherein the battery management computer includes at least one crash interface circuit (55) and a relay control link circuit (56) which performs a logical AND between a functional command (84) issued by the battery management computer (5) and a cutoff command (85) from the crash interface circuit (55).

4. Motor vehicle according to claim 3, wherein the crash interface circuit (55) is a hardware circuit, and wherein the relay control link circuit (56) is a hardware circuit.

5. A motor vehicle according to any one of claims 3 to 4, wherein the crash interface circuit (55) comprises a resistor load (R5) equivalent to the apparent resistance of a pyrotechnically tripped fuse.

6. Motor vehicle according to any one of claims 1 to 5, characterized in that the coil (BB1,BB2) of the relay or of each of the two relays is controlled on both sides, positive and negative, by the battery management computer (5).

7. Motor vehicle according to any one of claims 1 to 6, characterized in that the relay or both relays are normally open type relays.

8. Motor vehicle according to any one of claims 1 to 7, characterized in that the vehicle includes a service battery (6), configured to electrically supply the passive safety control unit (1) and the battery management computer (5).

9. Motor vehicle according to any one of claims 4 to 5, characterized in that the positive power line (41) and the negative power line (42) are devoid of pyrotechnically tripped fuses.

10. Motor vehicle according to any one of claims 1 to 8, characterized in that the passive safety control unit (1) is configured to further transmit to the battery management computer (5) at least one non-binary piece of information concerning the occurrence of a shock suffered by the vehicle.

Images