Protective device and method for protecting a traction battery

Abstract

The invention relates to a protective device and to a method for protecting a traction battery of an electric vehicle, comprising at least one crash sensor for detecting a crash, an onboard bus system for communication between vehicle components, a body control unit for coordinating the vehicle components, a thermal management control unit for controlling the thermal power flows in the vehicle, and a coolant pump for circulating a coolant through the traction battery. When a crash is detected, a crash signal is propagated onto the onboard bus system, and a thermal management control unit for controlling the coolant pump for the traction battery switches the coolant pump off.

Description

[0001] Description

[0002] PROTECTIVE DEVICE AND METHOD FOR PROTECTING A TRACTION BATTERY

[0003] The present disclosure generally relates to a protective device. More specifically, the present disclosure relates to a protective device for protecting a traction battery of an electric vehicle.

[0004] With lithium-based traction batteries, electric cars have now achieved ranges previously thought impossible. This long range is achieved, in part, by the very densely packed cells of the traction battery. In most modern electric vehicles, the traction battery is installed as a plate in the underbody. This means it takes up no additional space in the vehicle body, and the additional height is negligible compared to a vehicle with a combustion engine, which also has various technical components installed in the underbody. The cells used vary depending on the manufacturer. Some manufacturers use round cells, similar to those used in batteries for laptops and flashlights. In recent years, these cells have been steadily enlarged to increase energy density.When using round cells, the traction battery is usually designed with tall, narrow cooling channels running between the vertically positioned cells to cool them. The cooling channels are adapted to the outer radii of the cylindrical round cells and fit snugly against them. They are therefore comparatively complex to manufacture, but in return, they offer high cooling performance, as a relatively large portion of the outer surface of each cell is thermally coupled to the cooling channel, resulting in a relatively high cooling or heating performance of this concept.

[0005] Most manufacturers use prismatic cells for their traction batteries, which usually have cuboid-shaped housings. These cells are also usually installed upright in the traction battery, so the format is often such that these cells are wider than they are high, as the available height is limited due to the installation in the underbody. In traction batteries with prismatic cells, the cooling channels for temperature control of the battery usually run in the floor of the traction battery, so the prismatic cells are, so to speak, on the cooled or temperature-controlled floor and are thus temperature-controlled. There are also variants in which the cooling channels for temperature control also run between the prismatic cells. Since the cells are cuboid-shaped, the cooling channels only need to have a simple rectangular cross-section and are also linear.

[0006] The cells in a traction battery are connected in series to achieve a specific system voltage, e.g., 400 V. Often, parts of the cells are also connected in parallel to increase the available capacity. Regardless of whether cylindrical or prismatic cells are used, the wiring between the cells for series or parallel connection is always partially located on the top of the cells. With cylindrical cells, some of the wiring is also located on the bottom of the cells.

[0007] If such a vehicle is involved in a serious accident, the forces exerted during the accident can damage the traction battery. If the damage is so extensive that individual cells within the traction battery are also damaged, the separator in that cell, which electrically separates the anode and cathode, can be damaged. This results in a significant current flow within the cell, which heats up. This can lead to what is known as thermal overload, i.e. uncontrolled overheating of the cell due to the internal short circuit caused by the damaged separator. If the damage is so extensive that the cell casing and the adjacent cooling channel are damaged, coolant can leak out and enter the cell after an accident.Since most coolants used today are electrically conductive, this can contribute significantly to thermal overload. Even if it is not a cell that is damaged, but rather a cooling channel, electrically conductive coolant can leak out and flow into the internal structure of the traction battery. The problem is exacerbated by the fact that the coolant pump often continues to run after an accident, also referred to as a crash, because the known systems are not connected and the control unit for the coolant pump is essentially unaware of the crash. Even in a serious crash in which the traction battery is automatically electrically disconnected from the rest of the vehicle by contactors or similar, the coolant pump often continues to run because it and the control unit are powered by the 12V on-board electrical system, which uses the well-known car battery for power, which is not disconnected in the event of an accident / crash.

[0008] If the coolant pump continues to run after a crash with a leak in the cooling circuit, it will continuously pump coolant into the interior of the traction battery. Since cells are now densely packed, as described above, there is little free space to absorb the coolant, and so the level rises quickly. If it reaches the wiring above the cells, the conductive coolant can quickly cause short circuits, further exacerbating the consequences of the crash.

[0009] It is therefore an object of the embodiments of the present disclosure to provide a protective device for protecting a traction battery, which has increased protection against short circuits in the event of an accident with damage to the traction battery.

[0010] The object is achieved according to a first aspect with a protective device for protecting a traction battery of an electric vehicle having at least one crash sensor for detecting a crash, an internal vehicle bus system for communication between vehicle components, a body control unit for coordinating the vehicle components, a thermal management control unit for controlling the thermal power flows in the vehicle, a coolant pump for circulating a coolant through the traction battery, wherein upon detection of a crash by the crash sensor, a crash signal is propagated by the body control unit to the internal vehicle bus system, and upon detection of this crash signal by the thermal management control unit, the thermal management control unit switches off the coolant pump.

[0011] This measure ensures that if the coolant channels in the battery and / or the cells in the traction battery are damaged by shutting down the coolant pump, no additional electrically conductive coolant is pumped into the traction battery. This, in turn, drastically reduces the likelihood of a short circuit and thus increases vehicle safety in the event of an accident.

[0012] In the following, setting the operation of the coolant pump means switching off the coolant pump or regulating the coolant pump to a speed of 0.

[0013] In a preferred embodiment, the crash sensor for detecting a crash is connected directly to an airbag control unit, which reports a crash as a crash signal to the body control unit via the vehicle's internal bus system. This direct connection increases the reliability of crash detection. In particular, the airbag control unit can be configured to correctly interpret the sensor data to increase the reliability of crash detection. In some embodiments, the crash sensor is connected to the airbag control unit via a bus.

[0014] In another preferred embodiment, the thermal management control unit includes a pump controller. This modular design makes the thermal management control unit cheaper to manufacture and simpler to install. In other embodiments, the pump controller can also be part of another control unit or be a standalone control unit itself.

[0015] In another preferred embodiment, the coolant pump is connected to the pump control system via a power line. This has the advantage of operating and controlling the coolant pump via a single line. Thus, the system can be manufactured cost-effectively. In other embodiments, the power line and the control line can also be separate, for example, if the pump control system is part of the coolant pump.

[0016] In some embodiments, the coolant pump is operated with pulse width modulation, and the coolant pump's operation is adjusted by setting a pulse width modulation duty cycle to 0. This measure has the advantage of simple operation thanks to the proven pulse width modulation method, whereby the coolant pump's operation can be adjusted without adding an additional switch, meaning the coolant pump can be switched off. For this purpose, the pulse width modulation can be modulated onto the power line, which can simplify the control of the coolant pump.

[0017] According to a second aspect, an electric vehicle is provided. The electric vehicle comprises a traction battery and a system for controlling the temperature of the traction battery, wherein the protective device for protecting a traction battery according to the first aspect is installed in the electric vehicle.

[0018] According to a third aspect, the problem is solved with a method for protecting a traction battery of an electric vehicle, comprising the following steps: detecting a crash by means of a crash sensor, sending a crash signal to a body control unit, propagating the crash signal by the body control unit to an internal vehicle bus, detecting the crash signal by a thermal management control unit, and switching off a coolant pump by the thermal management control unit.

[0019] This process significantly increases vehicle safety by significantly reducing the likelihood of a short circuit in the traction battery through additional conductive coolant in the internal structure of the traction battery.

[0020] The crash sensor for detecting a crash can be connected directly to an airbag control unit, which interprets the sensor data from the crash sensor and, upon detection of a crash, reports it as a crash signal to the body control unit via the vehicle's internal bus system. This direct connection increases the reliability of crash detection. In particular, the airbag control unit can be configured to correctly interpret the sensor data to increase the reliability of crash detection.

[0021] The coolant pump can be operated with pulse width modulation, and the coolant pump can be switched off by setting a pulse width modulation duty cycle to 0. Thus, the operation of the coolant pump can be easily adjusted without adding another switch.

[0022] Preferred embodiments can be found in the dependent claims and the entire disclosure, whereby the presentation does not always distinguish in detail between device and use aspects; in any case, the disclosure is to be read implicitly with regard to all claim categories.

[0023] Further advantages, features, and details of the invention will become apparent from the following description of an exemplary embodiment and from the drawings, in which identical or functionally equivalent elements are provided with identical reference numerals. In the drawings:

[0024] Fig. 1 an electric vehicle with a traction battery and a system for temperature control of a traction battery, and

[0025] Fig. 2 shows an embodiment of a protective device for protecting a traction battery of a vehicle.

[0026] Fig. 1 shows an electric vehicle 4 with a traction battery 41, which is kept at an optimal temperature by means of a system 42 for temperature control of a traction battery. The system for temperature control of a traction battery 42 has a protective device 1 for protecting the traction battery 41 with components not shown here, such as a coolant pump 11 and a pump controller 31, and further components not shown, such as lines for receiving the coolant and cooling channels in the traction battery 41. A coolant flows through the traction battery, which has good thermal contact with the cells of the traction battery 41. The coolant is pumped through the traction battery by the coolant pump 11. It is also pumped through other components, such as a heating unit and / or a cooling unit, in order to be brought to the temperature required for the traction battery.Not all components in the circuit always have to be integrated; rather, individual components can be added or removed from the circuit using suitable valves. A multi-valve called an "octovalve" is often used for this purpose. This can direct the coolant flow through various components, allowing the exchange of heating or cooling energy between the individual components of the electric vehicle.

[0027] The term coolant requires explanation here, as the coolant not only serves to cool the traction battery 41 when it is in danger of becoming too hot, but also to heat it when it is too cold, for example, in winter. The cooling circuit is therefore not a cooling circuit per se, but rather a temperature control circuit, meaning that the coolant pump 11 is not a coolant pump in the literal sense, but rather a temperature control pump. The same applies to the coolant channels mentioned at the beginning, which should also be called temperature control channels. However, since the terms coolant, cooling circuit and coolant pump have long been established in the automotive sector, these terms will continue to be used, albeit with the above context, so that they are to be regarded not exclusively as cooling elements, but as temperature control elements.

[0028] Fig. 2 shows a schematic diagram of a protective device 1 for protecting a traction battery of a vehicle. The protective device 1 has at least one sensor 5 for detecting a serious crash or accident with deployment of at least one restraint system or airbag. In the following, the term crash is used for a collision or accident, so the sensor 5 is also referred to below as crash sensor 5. The crash sensor 5 can be installed, for example, in an airbag module. Most often, however, the crash sensor 5 is installed in the front of the vehicle or in a side structure of the vehicle, e.g. in the front apron below the hood, in a side door or in a pillar, in particular in the B-pillar or center pillar. Often, however, two sensors 5 are installed to achieve a certain degree of redundancy.These sensors 5 are then often arranged more towards the side of the front apron, with one crash sensor 5 on the right side of the front apron and the other crash sensor 5 on the left side of the front apron. This ensures better detection of a crash in the event of a laterally offset impact. The sensors 5 are usually acceleration sensors. However, the sensors 5 can also react to deformation of the front apron. Each crash sensor is usually connected to an airbag control unit 7, i.e. a control unit for the airbags, via its own line 21. However, since the English terms are also used in the automotive world in German-speaking countries, the term airbag control unit 7 will be used here as well for the control unit for the airbags. However, instead of a separate line, the crash sensors 5 can also be connected to the airbag control unit 7 via a bus system.

[0029] If a vehicle is involved in an accident or collision (as already indicated above, hereinafter referred to as a crash) and collides with an obstacle, the crash sensor 5 is activated and reports its sensor data via line 21 to the Airbag Control Unit 7. This interprets the sensor data and determines whether the crash is serious or a minor accident below the airbag deployment threshold. The Airbag Control Unit 7 is connected to a Body Control Unit 2 via an internal vehicle bus. The Body Control Unit 2 is the central control unit of the vehicle; this is where all information concerning the body and the vehicle converges. The Body Control Unit 2 controls, for example, all the lights of the

[0030] The vehicle's internal bus also contains the sensor data from the vehicle's sensors. Here, too, the term "Body Control Unit 2" has become established for this central control unit in German-speaking countries, so this term will be used synonymously with "central control unit" in the following. The vehicle's internal bus can, for example, be used for the following:

[0031] B. a CAN bus (ISO 11898-1:2015 - Road vehicles — Controller area network (CAN) —

[0032] Part 1: Data link layer and through which many of the vehicle's control units are connected. However, any other suitable bus can also be used, such as a FlexRay bus (ISO 17458-4:2013(en), Road vehicles — FlexRay communications system — Part 4: Electrical physical layer specification) or an automotive Ethernet bus (ISO 21111-1:2020(en), Road vehicles — In-vehicle Ethernet — Part 1: General information and definitions).

[0033] The Airbag Control Unit 7 now interprets the sensor data from crash sensor 5, and if it concludes that a crash has occurred, it reports this crash to the Body Control Unit 2 via a crash signal 23. The Airbag Control Unit 7 can also be additionally connected to the Body Control Unit 2 via a second line to ensure redundant signal processing. The second line can be a direct line or a second internal vehicle bus. After receiving the crash signal 23, the Body Control Unit 2 immediately propagates this crash signal 23 to the entire internal vehicle bus so that it can be received by all control units connected to this bus.

[0034] This crash signal 23 is also received by a thermal management control unit 3, which regulates the thermal energy flows within the vehicle and is part of the system for controlling the temperature of a traction battery 41. The thermal management control unit 3 has a pump control 31, to which a coolant pump 11 is connected via a dedicated line 29. The coolant pump 11 serves to pump coolant through the traction battery 41 in order to control its temperature.

[0035] The pump controller 31 integrated in the Thermal Management Control Unit 3 controls the coolant pump 11 using a pulse-width modulated (PWM) signal 27 to achieve optimal performance in controlling the temperature of the traction battery. The pulse-width modulated signal 27 is also referred to below as the PWM signal 27. The PWM signal 27 has a duty cycle with which the power output and thus the speed of the coolant pump can be regulated. The Thermal Management Control Unit 3 then transmits the crash signal 23 to the pump controller 31, which then sets the duty cycle of the PWM signal 27 to 0, thus deactivating the coolant pump and regulating the speed to 0.

[0036] This means that in the event of a crash, the coolant pump is shut off almost immediately (within milliseconds), preventing any further electrically conductive coolant from entering the traction battery 41 in the event of damage to the traction battery. This greatly reduces the likelihood of a short circuit in the traction battery 41 and significantly increases the safety of the system and the vehicle.

[0037] Although at least one exemplary embodiment has been shown in the foregoing description, various changes and modifications may be made. The aforementioned embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. Rather, the foregoing description provides those skilled in the art with a road map for implementing at least one exemplary embodiment; numerous changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the appended claims and their legal equivalents. Furthermore, multiple modules or multiple products may be connected together in accordance with the principles described herein to obtain additional functions.

[0038] List of reference symbols

[0039] 1. Protective device for the protection of traction batteries

[0040] 2. Body Control Unit (BCU) /

[0041] 3. Thermal Management Control Unit

[0042] 4. Electric vehicle with traction battery

[0043] 5. Crash sensor

[0044] 11. Coolant pump for the traction battery

[0045] 21. Crash detection signal on the hard-wired line

[0046] 22. Hardwired line

[0047] 23. Crash detection signal on the vehicle bus

[0048] 25. In-vehicle bus system

[0049] 27. Shutdown signal for the coolant pump

[0050] 29. Power line with modulated PWM signal for the coolant pump

[0051] 31. Pump control

[0052] 41. Traction battery

[0053] 42. System for temperature control of a traction battery

Claims

Patent claims 1. Protective device (1) for protecting a traction battery (41) of an electric vehicle (4) comprising: - at least one crash sensor (5) for detecting a crash, - an internal vehicle bus system (25) for communication between vehicle components, - a Body Control Unit (2) for coordinating the vehicle components, - a Thermal Management Control Unit (3) for controlling the thermal power flows in the vehicle, and - a coolant pump (11) for circulating a coolant through the traction battery, wherein upon detection of a crash by the crash sensor (5), a crash signal (23) is propagated by the body control unit (2) to the vehicle-internal bus system (25), and upon detection of this crash signal (23) by the thermal management control unit (3), the thermal management control unit (3) switches off the coolant pump (11).

2. Protection device according to claim 1, characterized in that the crash sensor (5) for detecting a crash is connected directly to an airbag control unit (7), which is set up to interpret the sensor data of the crash sensor (5) and, upon interpretation of a crash, to report this as a crash signal (23) via the vehicle-internal bus system (25) to the body control unit (2).

3. Protection device according to one of claims 1 or 2, characterized in that the thermal management control unit (3) has a pump control (31).

4. Protection device according to claim 3, characterized in that the coolant pump (11) is connected to the pump control (31) by means of an energy-carrying line (29).

5. Protection device according to one of claims 1 to 4, characterized in that the pump control (31) is designed to operate the coolant pump (11) with a pulse width modulation (27), and the switching off of the coolant pump by setting a duty cycle of the pulse width modulation (27) to the value 0. A protective device according to claim 5, characterized in that the pump controller (31) is configured to modulate the pulse width modulation (27) onto the power-carrying line (29). An electric vehicle (4) comprising a traction battery (41) and a system for controlling the temperature of the traction battery (42), wherein the system for controlling the temperature of the traction battery (42) comprises a protective device (1) for protecting the traction battery (41) according to one of claims 1 to 6. A method for protecting a traction battery (41) of an electric vehicle (4), comprising the following steps: - Detecting a crash using a crash sensor (5), - Sending a crash signal (23) to a body control unit (2), - Propagating the crash signal (23) through the Body Control Unit (2) to an internal vehicle bus (25), - Detection of the crash signal by a Thermal Management Control Unit (3), and - Switching off a coolant pump (11) by the Thermal Management Control Unit (3). Method according to claim 8, characterized in that the crash sensor (5) is connected directly to an airbag control unit (7) for detecting a crash, which interprets sensor data from the crash sensor (5) and, upon interpretation of a crash, reports this as a crash signal (23) via the vehicle-internal bus system (25) to the body control unit (2). Method according to one of claims 8 or 9, characterized in that the coolant pump (11) is operated with pulse width modulation (27), and the coolant pump is switched off by setting a duty cycle of the pulse width modulation (27) to the value 0.

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