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

Abstract

Electric or hybrid motor vehicle, comprising a traction battery (2) equipped with two isolation relays (R1, R2) capable of electrically isolating the traction battery from the rest of the vehicle by interrupting the positive (41) and negative (42) power lines respectively, the vehicle comprising a passive safety control unit (1) coupled to acceleration sensors (11), and configured to activate a plurality of occupant protection members in the event of an impact, the two isolation relays being controlled directly by the passive safety control unit (1), an opening activation of the isolation relays being carried out substantially simultaneously with an activation of all or part of the plurality of occupant protection members, in the event of an impact. Figure 2

Description

Title of the invention: VEHICLE COMPRISING A SYSTEM FOR DISCONNECTING THE TRACTION BATTERY BY 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 relates to a vehicle comprising a traction battery disconnection system in the event of an impact by means of a passive safety control unit.

[0002] It should be noted from the outset that the passive safety control unit is called in practice in the trade “airbag calculator”.

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

[0004] It should be noted that such a disconnection system (one can also say 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 suffered by the vehicle, it is very difficult, and in practice impossible, to predict the damage suffered by the structure of the vehicle, and in particular the precise time sequence of the occurrence of this damage. The diversity of possible shock configurations and intensities is almost unlimited.

[0006] In known configurations where the passive safety control unit transmits crash information to the battery management computer which interrupts the power supply lines from the traction battery, this process requires a few hundred milliseconds and it is not excluded that the crash information is not received or that the cutting action is not executed correctly.

[0007] The inventors sought to overcome such a response time of a few hundred milliseconds, so that the total time of the line interruption process does not exceed a few tens of milliseconds. A total line interruption time of less than a few tens of milliseconds allows the process to be executed before the occurrence of structural degradations which can cause short circuits or cuts in electrical connections.

[0008] 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 by relative to the rest of the vehicle by interrupting the positive power line, the vehicle comprising a passive safety control unit coupled to acceleration sensors, and configured to activate a plurality of occupant protection members in the event of an impact, characterized in that the isolation relay is controlled directly by the passive safety control unit, an activation of opening of the isolation relays being carried out substantially simultaneously with an activation of all or part of the plurality of occupant protection members, in the event of an impact.

[0009] Thanks to the provisions promoted 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 which can cause short circuits or cuts in power lines.

[0010] Advantageously, it is the entity responsible for activating and deploying the occupant protection means which also simultaneously and directly generates the opening of the isolation relay or of the two isolation relays when there are two. There is no delay in transmitting information or processing in another entity.

[0011] Advantageously, the opening of the isolation relay is done at nominal current and it is not necessary to provide for being able 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.

[0012] It should be understood that the battery management computer does not intervene, in this circumstance, in the process of interrupting the power lines connected to the high voltage battery.

[0013] It should be noted that the term "isolation relay" covers any device acting as an isolation contactor, i.e. a member which can be selectively controlled by an electrical signal, reversibly, either to an electrically open state or to an electrically closed state.

[0014] The term “rest of the vehicle” means all components of the vehicle other than the battery.

[0015] It should be noted that the positive power line is coupled to the positive terminal of the traction battery. The negative power line is coupled 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.

[0016] A passive safety system for protecting occupants is commonly referred to as an airbag system or airbag system. Such a passive safety system includes one or more acceleration and / or deceleration sensors and is capable to determine ultra-quickly and precisely the intensity of the impact suffered and its nature (frontal impact, side impact, rear impact, rollover, etc.). Depending on the knowledge of the impact suffered, the passive safety system can determine the severity of the impact, and trigger the opening of the isolation relays if necessary.

[0017] It is 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 to carry out the emergency interruption in the event of a crash.

[0018] According to a useful option 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 the positive and negative power lines respectively, the vehicle being characterized in that the two isolation relays are controlled directly by the passive safety control unit, an opening activation of the two isolation relays being carried out substantially simultaneously with an activation of all or part of the plurality of occupant protection members, in the event of an impact.

[0019] The two high voltage power lines are interrupted, i.e. not only the positive line as previously, but also the negative line which is not connected to the vehicle ground (it is floating with respect to the ground).

[0020] According to an advantageous option, the vehicle further comprises a battery management computer, characterized in that the coil of the relay or of each of the two relays is controlled on one side by the passive safety control unit and the coil of the relay or of each relay is controlled on the other side by the battery management computer.

[0021] In practice, the coil of each of the two relays is controlled on at least one positive side by the passive safety control unit and on one negative side by the battery management computer.

[0022] According to one embodiment, the relay or the two relays are normally open type relays.

[0023] As a result, 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 untimely interruption of the electrical supply, then the two isolation relays are open.

[0024] According to one embodiment, a control power supply line is provided, configured to supply power to the coil of the relay or the coils of the two relays via an activation switch of the passive safety control unit.

[0025] It is said control power supply line, common to both relays, which is cut off in an emergency, in the event of a crash, by the airbag computer.

[0026] The activation switch inside the airbag computer can be a MOSFET type transistor, a PNP transistor, or even a relay or any other switching means. This activation switch is in the positive control switch position relative to the relay coil, also called a High Side switch in the language of the electronics trade.

[0027] According to one embodiment, there is also provided on said power supply line an interruptible portion actuable by voluntary manual action by a professional operator. This is a case of non-accident life, for example for securing the battery during maintenance interventions.

[0028] The control power supply line is supplied by a conventional voltage from the ordinary battery, for example 12 volts.

[0029] It is noted that the first positive voltage can typically be a 12 volt type voltage (conventional on-board network).

[0030] According to one embodiment, the battery management computer selectively controls a closing and an opening of the relay or of each of the two relays, by means of at least one main electronic switch, for example of the MOSFET type, while the passive safety control unit keeps the control power supply line energized.

[0031] According to one embodiment, the positive power line and the negative power line are devoid of a pyrotechnic trigger fuse.

[0032] As a result, the proposed solution is simple, effective and inexpensive, while in practice it performs the function performed by the pyrotechnic device present in known art configurations.

[0033] According to one embodiment, a thermally triggered fuse is further provided, either on the positive power line or on the negative power line.

[0034] The function of the thermal fuse (with non-reversible triggering) is different and complementary to the function of the isolation relays. The two devices coexist in the same electrical power circuit.

[0035] According to one embodiment, the battery management computer is configured to control the two isolation relays with a time shift of a few tens or hundreds of milliseconds.

[0036] For the relay bonding process, this allows a pre-charging function of the capacitive loads to be performed. One of the two relays is bonded and the other relay is supplemented in parallel by a series resistance pre-charging circuit. The second relay is then bonded after a few hundred milliseconds, once the capacitive loads have been powered.

[0037] For the opening of the relays, we can also apply a small time shift to alternate the effect of the power cut on the straw, it is the relay which is opened in first which interrupts the current and undergoes the arc, and the other relay, opened after, at zero current, is preserved.

[0038] It should be noted that the interruption command by the airbag computer is not differentiated, i.e. the two relays are opened strictly at the same time due to the cutting of the control power supply line which is common.

[0039] According to one embodiment, the positive control line of the relay coil or of each relay coil passes through the activation switch and through an auxiliary electronic switch of the battery management computer.

[0040] In other words, the positive control line of a relay coil first passes through the activation switch present in the airbag computer and then through the auxiliary electronic switch provided on the high side in the battery management computer. In practice, there are therefore two transistors in series on the high side control.

[0041] According to one embodiment, the passive safety control unit is configured to transmit to the battery management computer at least one item of information concerning the emergency opening triggering of the control power supply line. This information passes through a digital network, e.g. a CAN bus or similar.

[0042] As a result, 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.

[0043] According to one embodiment, the battery management computer has no reservoir capacity. The airbag computer has a reservoir capacity and this is used to trigger the occupant protection devices and also to cause the activation switch to open, even if the incident electrical power supply to the airbag computer disappears in the very first moments of the crash.

[0044] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which: - [Fig.l] schematically illustrates a side view of an electric vehicle in which a battery isolation system according to the present invention is implemented; - [Fig.2] shows a schematic electrical diagram of part of a electric or hybrid vehicle illustrating the present invention; - [Fig.3] shows an example of a timing diagram illustrating the control of the isolation relay in a nominal case and in the event of a shock occurring; - [Fig.4] shows an example of an auxiliary interrupt device; - [Fig.5] is analogous to [Fig.2], and shows a simplified case of a confi- single isolation relay configuration.

[0045] In the various figures, the same references designate identical or similar elements. For reasons of clarity of the description, certain elements are not necessarily represented to scale, in particular concerning the timings and time intervals of the chronograms.

[0046] We are interested here in an electric or hybrid vehicle with an electric powertrain.

[0047] 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 relative to the local ground and the Y direction perpendicular to the two previous ones and corresponds to the transverse direction of the vehicle.

[0048] In a motor vehicle 9 with electric propulsion / traction, there is a traction battery 2 which is designed to store a significant quantity of electrical energy in electrochemical form. The traction battery is an electrical energy storage device, more concisely called 'electric battery' or even 'battery', and 'battery pack' when including the mechanical protection and electrical protection components which will be discussed in this document.

[0049] Concerning the quantity of energy stored in the battery pack, in practice we are talking about several tens of kWh. A 100% electric vehicle battery has an energy storage capacity typically between 50 kWh and 100 kWh, depending on the target autonomy, the weight and the consumption of said vehicle, and a little less for a plug-in type hybrid vehicle. The battery 2 is recharged using a charging base 94 as known per se.

[0050] In the case of mild hybrid vehicles, the voltage of the traction battery may be lower, eg 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.

[0051] The most common traction batteries on electric vehicles are batteries based on Lithium-Ion type electrochemistry, 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 unit electrochemical cells, arranged in series and / or in parallel.

[0052] The battery pack has a fairly high voltage at its terminals (B+, B-), in practice greater than 100 volts, most often between 200 volts and 800 volts. Voltages greater than 800 volts are also not excluded.

[0053] The voltage of this type of battery thus extends beyond the very low voltage (VLV) range and it is necessary to take precautions; there are indeed regulatory protection requirements, particularly with regard to possible contacts. induced by an action by an operator (e.g. an emergency responder) either with bare hands or using a tool, or any other unwanted contact following a mechanical shock suffered (case of 'crash').

[0054] The occupant protection system comprises airbags. Among the airbags shown in [Fig.l], 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' head side airbags 34. An occupant protection system also comprises seat belt pretensioners 31 which make it possible to lock the reels and cancel out any play in the seat belts on the occupants' bodies. It is not excluded to have other inflatable protection means known per se.

[0055] The occupant protection system comprises a passive safety control unit 1, also called an “Airbag computer”. Said computer is usually positioned in the vicinity of the nominal center of gravity of the vehicle.

[0056] The occupant protection system includes acceleration sensors 11 also called accelerometer sensors or impact sensors. The Airbag computer filters the information provided by the accelerometer sensors.

[0057] The passive safety control unit 1 comprises a microcontroller 10, an entity known per se and therefore not described here in detail. The passive safety control unit 1 is powered by an input 14 coming from the ordinary 12-volt on-board network and also comprises a reservoir capacity 16, which gives the passive safety control unit sufficient autonomy to operate for a certain time even in the event of the incident power supply 14 disappearing during the occurrence of a crash. The certain time in question is sufficient to ignite, if necessary, all the igniters 12 of the occupant protection devices. In the present case, the reservoir capacity 16 is also used to ensure that the power lines connected to the traction battery 2 are interrupted, as will be seen below.

[0058] The electrical system of the vehicle comprises a high-voltage network, which supplies in particular the inverter(s) of the electric traction motors as well as a DC / DC converter which makes it possible to supply in cascade a second low-voltage on-board network, here for example a 12-volt network, of which a 12-volt battery marked 6 and illustrated in [Fig.2] forms part.

[0059] The battery pack 2 is associated with a battery management computer 5, commonly referred to in English as BMS (Battery Management System).

[0060] 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 that connect the battery 2 to the computer 5. It should be noted that the interface between the battery and The battery management calculator can be more complete and complex, with additional functions not detailed here.

[0061] The battery management calculator 5 comprises a microcontroller 50, an entity known per se and therefore not described here in detail.

[0062] The battery pack further comprises two isolation relays RI, R2.

[0063] 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 relative to the chassis of the vehicle.

[0064] These relays RI, R2 are power relays, their contacts support a permanent current of several hundred amperes, and up to 1500 amperes at peak. These power relays have a nominal breaking capacity of at least several hundred amperes under load, and more than 1000 amperes at least once.

[0065] On the control side, the first relay RI comprises a coil marked BB1, the second relay R2 comprises a coil marked BB2. Both relays are normally open type relays. As known per se, current must flow through the coil to cause the contact to close. Conversely, if there is no current flowing through the coil, the relay contact is returned to the open state by an elastic element such as a spring.

[0066] When the two relays RI, R2 are open, there is no longer any voltage on the HV+ and HV- power lines, downstream, marked 41a and 42a in [Fig.l]. Under this condition, a possible electrical risk linked to the high HV voltage in the rest of the vehicle is avoided.

[0067] In a variant not shown in the figures, it would not be excluded to use a single relay with double isolated contacts to simultaneously interrupt the positive power line and the negative power line.

[0068] 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-.

[0069] The electrical conductors forming these power lines and conveying the currents delivered by the battery can be metal bus bars 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.

[0070] In addition, a conventional thermally triggered 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.

[0071] It should be noted that the positive power line or the negative power line can be equipped with a current sensor, not shown in [Fig.2], for example in this case a shunt at the terminals of which a voltage drop is measured.

[0072] Optionally according to the present invention, the airbag computer 1 transmits to the battery management computer 5 non-binary information concerning the occurrence of an impact suffered by the vehicle.

[0073] For this purpose, it is provided that the battery management computer 5 and the airbag computer communicate via a multiplexed network 92, for example a CAN type network. There is no wired electrical connection specifically connecting the airbag computer and the battery management computer.

[0074] In the example illustrated, 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 may be the general computer for controlling the body functions (Body Controller) or a computer for managing the powertrain (with or without a heat engine).

[0075] Relay control circuit

[0076] The control power supply line of the first relay RI leaves the positive terminal 60 of the 12 volt battery 6 along a first portion of line 61, then it enters the airbag computer 1, where it passes through an activation switch marked TA and leaves to go towards the battery management computer 5 along a second portion of line 62.

[0077] An interruptible portion (respectively marked 71 and 72) may be provided on the first portion of line or on the second portion of line, which can be activated by voluntary manual action by a professional operator and discussed below.

[0078] Inside the battery management computer 5, the control power supply line of the first relay passes through an auxiliary electronic switch T1H then leaves the battery management computer to go, along the third portion of line 63, to one of the terminals of the coil of the relay RI denoted BB1. The other terminal of the coil BB1 is connected by a fourth portion 64 to a main activation switch T11 configured to pull to ground.

[0079] Switches TA, T1H and T2H are P-channel MOSFETs or PNP type transistors. For MOSFETs, the hot point is called Source and the cold point is called Drain.

[0080] The T1L and T2L switches are N-channel MOSFETs or NPN type transistors. For MOSFETs, the hot point is called Drain and the cold point is called Source.

[0081] The control supply line of the second relay R2 has a first part common with the control supply line of the first relay.

[0082] Inside the battery management computer 5, the control power supply line of the second relay passes through a second auxiliary electronic switch T2H then leaves the battery management computer to go, along the third portion of line 65, to one of the terminals of the coil of the relay R2 denoted BB2. The other terminal of the coil BB2 is connected by a fourth portion 66 to a second main activation switch T2L configured to pull to ground.

[0083] The gates or bases of the switches T1H, T1L, T2H, T2L are controlled by the microcontroller 50 of the battery management computer 5.

[0084] The gate or base of the TA activation switch is controlled by the microcontroller 10 of the airbag computer.

[0085] Turning to [Fig.3], the abscissa axis carries time and the ordinate axis carries the logical states LogST, a high state representing an active state (or a passing state in the case of a switch).

[0086] With reference to [Fig. 3], the first part of the timing diagram illustrates a conventional opening of the relays at the initiative of the battery management computer 5, for example when the vehicle enters a rest state of the electric traction chain. At time t1, the switches T1H, T1L, T2H, T2L are deactivated, they go to the blocked state; the coils then no longer being powered, the contacts open.

[0087] The second part of the timing diagram illustrates a closing of the relays at the initiative of the battery management computer 5, for example when the electric traction chain is again requested. At time t2, the switches T1H, T1L, T2H, T2L are activated, with optionally a time shift d2, they go to the on state and the coils being powered again, the contacts of the relays R1, R2 close and current can pass into the traction chain.

[0088] The third part of the timeline illustrates a crash case.

[0089] In these circumstances, the TA activation switch is deactivated at the initiative of the airbag computer 1 alone, without intervention from the battery management computer 5. The deactivation of the TA activation switch causes the interruption of the current in the coils BB1, BB2 of the two relays.

[0090] With reference to the zoom on the right of [Fig.3], the instant t0 materializes the start of the shock suffered by the vehicle. The instant t3 materializes the ignition of the protection means and the deactivation of the activation switch TA. The relays RI, R2 open at the instant t4.

[0091] The time interval dl, reaction time, is in practice between 30 milliseconds and 40 ms.

[0092] With reference to [Fig.4], an interruptible portion (actuable by voluntary manual action of a professional operator) comprises a breakable loop 75 and a main switch 76, one or the other being accessible by operators of emergency services (e.g. firefighters and / or first aid, or even vehicle repair operator).

[0093] The airbag calculator includes a process for filtering the raw acceleration information, this process is represented by the block CC in [Fig.3]; it precedes the instant t3 of the ignition of the protection means and the deactivation of the activation and transmission switch of the impact notification.

[0094] 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.

[0095] The early interruption of the high voltage HV network by opening the relays RI and R2 has no short-term effect on the power supplied by the 12 volt battery 6.

[0096] Single-relay mild hybridization configuration

[0097] In these mild hybridization configurations, eg with a voltage lower than 60 Volts, the negative terminal B- of the MH BATT battery is connected to the chassis, as shown in [Fig.5].

[0098] From then on, the second relay is no longer present, the negative power line is directly connected to ground, that is to say to the chassis of the vehicle.

[0099] Opening the first RI relay is sufficient to eliminate any problematic voltage from the downstream HV user network.

[0100] The power supply line for the control of the first relay RI remains identical to what has been described in relation to [Fig.2]. The operating logic is identical or similar, mutatis mutandis, to what has already been described previously.

Claims

Claims

1. Electric or hybrid motor vehicle, comprising a traction battery (2) equipped with at least one isolation relay (RI) capable of electrically isolating the traction battery from the rest of the vehicle by interrupting at least the positive power line (41), the vehicle comprising a passive safety control unit (1) coupled to at least acceleration sensors (11), and configured to activate a plurality of occupant protection members in the event of an impact, characterized in that the isolation relay (RI) is controlled directly by the passive safety control unit (1), an opening activation of the isolation relay being carried out substantially simultaneously with an activation of all or part of the plurality of occupant protection members, in the event of an impact.

2. Motor vehicle according to claim 1, in which the traction battery is equipped with two isolation relays (R1, R2) capable of electrically isolating the traction battery by interrupting the positive (41) and negative (42) power lines respectively, characterized in that the two isolation relays are controlled directly by the passive safety control unit, an opening activation of the two isolation relays being carried out substantially simultaneously with an activation of all or part of the plurality of occupant protection members, in the event of an impact.

3. Motor vehicle according to any one of claims 1 to 2, wherein the vehicle further comprises a battery management computer (5), characterized in that the coil (BB1, BB2) of the relay or of each of the two relays is controlled on one side by the passive safety control unit (1) and the coil of the relay or of each relay is controlled on the other side by the battery management computer (5).

4. Motor vehicle according to any one of claims 1 to 3, characterized in that the relay or both relays are normally open type relays.

5. Motor vehicle according to any one of claims 1 to 4, characterized in that a control supply line (61, 62) is provided, configured to supply power to the coil of the relay or the coils of the two relays via an activation switch (TA) of the passive safety control unit.

6. Motor vehicle according to claim 5, characterized in that the battery management computer selectively controls a closing and an opening of the relay or of each of the two relays, by means of at least one main electronic switch, for example of the MOSFET type (T1L, T2L), while the passive safety control unit (1) keeps the control power supply line energized.

7. Motor vehicle according to any one of claims 5 to 6, characterized in that the positive power line and the negative power line are without a pyrotechnic trigger fuse.

8. Motor vehicle according to any one of claims 1 to 7, characterized in that a thermally triggered fuse (21) is further provided either on the positive power line (HV+) or on the negative power line (HV-).

9. Motor vehicle according to any one of claims 5 to 7, characterized in that a positive control line (62,63,65) of the relay coil or of each relay coil passes through the activation switch (TA) and through an auxiliary electronic switch (T2H,T2H) of the battery management computer.

10. Motor vehicle according to any one of claims 1 to 9, characterized in that the passive safety control unit (1) is configured to transmit to the battery management computer (5) at least one item of information concerning the triggering of emergency opening of the control power supply line.

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