Battery system and vehicle including the same

Abstract

The present disclosure relates to a battery system and an electric vehicle including the battery system. The battery system includes a high-voltage battery having a plurality of interconnected battery cells for providing a high-voltage output at battery system terminals of the battery system, and a battery disconnect element for disconnecting the high-voltage battery from at least one of the battery system terminals in the event of a fault or a crash, wherein the battery disconnect element is powered by the high-voltage battery.

Description

Technical Field

[0001] The present invention relates to a battery system comprising a high-voltage battery and a battery disconnect element for disconnecting the high-voltage battery from at least one of the battery system terminals in the event of a fault or a crash. Furthermore, the present invention relates to a vehicle comprising such a battery system. Background Art

[0002] In recent years, vehicles for transporting goods and people have been developed that use electricity as a power source. Such electric vehicles are cars that are driven by an electric motor using energy stored in a rechargeable battery. Electric vehicles can be powered solely by batteries or can be hybrid vehicles powered by, for example, a gasoline generator. In addition, vehicles can include a combination of an electric motor and a traditional internal combustion engine. Generally, an electric vehicle battery (EVB) or traction battery is the battery used to power a battery electric vehicle (BEV). Electric vehicle batteries differ from starting batteries, lighting batteries, and ignition batteries in that they are designed to provide power for sustained periods of time. A rechargeable or secondary battery differs from a primary battery in that it can be repeatedly charged and discharged, whereas a primary battery only provides the irreversible conversion of chemical energy into electrical energy. Low-capacity rechargeable batteries are used as power sources for small electronic devices such as cell phones, laptop computers, and video cameras, while high-capacity rechargeable batteries are used as power sources for hybrid vehicles and the like.

[0003] In general, a rechargeable battery comprises an electrode assembly, a housing for accommodating the electrode assembly, and electrode terminals electrically connected to the electrode assembly, wherein the electrode assembly comprises a positive electrode, a negative electrode, and a separator inserted between the positive electrode and the negative electrode. An electrolyte solution is injected into the housing so as to charge and discharge the battery via an electrochemical reaction of the positive electrode, the negative electrode, and the electrolyte solution. The shape of the housing, such as cylindrical or rectangular, depends on the intended purpose of the battery. Lithium-ion (and similar lithium polymer) batteries, which are widely known through their use in laptop computers and consumer electronics, dominate the latest developed electric vehicles.

[0004] Rechargeable batteries can be used as battery modules, formed by coupling multiple battery cells in series and / or parallel, to provide high energy density, particularly for hybrid vehicle motor drives. That is, depending on the required amount of power and to achieve high-power rechargeable batteries, a battery module is formed by interconnecting the electrode terminals of multiple battery cells.

[0005] The battery module can be constructed in a block design or a modular design. In the block design, each battery is coupled to a common collector structure and a common battery management system, and its cells are arranged in a housing. In the modular design, multiple battery cells are connected to form a submodule, and several submodules are connected to form a battery module. In automotive applications, the battery system typically consists of a plurality of battery modules connected in series to provide the desired voltage. Among them, the battery module may include a submodule with a plurality of stacked battery cells, each stack including cells connected in series and in parallel (XpYs) or cells connected in parallel and in multiple series (XsYp).

[0006] A battery pack is a group of any number of (preferably identical) battery modules. They can be connected in series, parallel, or a mix of both to provide the desired voltage, capacity, or power density. The components of a battery pack include the individual battery modules and the interconnects that provide electrical conductivity between them.

[0007] To meet the dynamic power demands of various electrical consumers connected to the battery system, static control of battery power output and charging is insufficient. Therefore, a stable information exchange is required between the controllers of the battery system and the electrical consumers. This information includes the actual state of charge, SoC, potential electrical performance, charging capacity and internal resistance of the battery system, as well as the actual or predicted power demand or surplus of the device. Therefore, the battery system typically includes a battery management system (BMS) to obtain and process this information at the system level, and also includes multiple battery module managers (BMMs), which are part of the system's battery modules and obtain and process relevant information at the module level. In particular, the BMS typically measures the system voltage, system current, local temperatures at different locations within the system housing, and the insulation resistance between the live components and the system housing. Additionally, the BMM typically measures the individual cell voltages and temperatures of the battery cells in the battery module.

[0008] Thus, a BMS / BMU is provided for managing the battery pack, such as by protecting the batteries from operating outside their safe operating area, monitoring their status, calculating secondary data, reporting that data, controlling their environment, authenticating the batteries, and / or balancing the batteries.

[0009] Under abnormal operating conditions, the battery pack should generally be disconnected from the load connected to the terminals of the battery pack. Therefore, the battery system also includes a battery disconnect unit (BDU), which is electrically connected between the battery module and the battery system terminals. Therefore, the BDU is the main interface between the battery pack and the vehicle's electrical system. The BDU includes an electromechanical switch that disconnects or connects the high current path between the battery pack and the electrical system. The BDU provides feedback, such as voltage and current measurement, to the battery control unit BCU accompanying the battery module. The BCU uses a low current path to control the switches in the BDU based on the feedback received from the BDU. Therefore, the main functions of the BDU may include controlling the current between the battery pack and the electrical system and current sensing. The BDU can also manage additional functions such as external charging and pre-charging. In order to disconnect the battery in the event of a battery failure or in the event of a collision of the electric vehicle carrying the battery, pyrotechnic elements are generally used.

[0010] Typically, the BDU is powered by the low-voltage power supply of the electric vehicle (typically a 12V car battery). To ensure that the power required for disconnection, especially for triggering pyrotechnic elements, is available even in the event of a sudden disconnection from the low-voltage power supply, capacitors are used to store the required energy.

[0011] DE 10 2012 215 074 A1 describes a battery-powered unit (BDU) that includes such a capacitor. The BDU includes a pyrotechnic switch and a separate thermal trigger element, which is arranged in a circuit with the pyrotechnic switch. When the battery temperature exceeds a certain threshold, the thermal trigger element triggers, closing the circuit connecting the pyrotechnic switch to the capacitor serving as a power source. This triggers the pyrotechnic switch, disconnecting the battery from the battery system terminals and, consequently, the vehicle's electrical system.

[0012] BDUs that rely on capacitors for energy storage are complex because multiple components are required to ensure the desired release of the pyrotechnic elements. Furthermore, if the low-voltage power supply is disconnected from the BDU not suddenly but for an extended period (e.g. due to a damaged connecting cable), the capacitors cannot charge and, therefore, the pyrotechnic elements cannot operate.

[0013] It is therefore an object of the present invention to overcome or reduce at least some of the disadvantages of the prior art and to provide a less complex battery system that can be safely and reliably disconnected from the vehicle's electrical system in the event of a fault or crash. Summary of the Invention

[0014] Embodiments of the present disclosure seek to address, at least to some extent, at least one of the problems found in the prior art.

[0015] According to the present invention, a battery system for an electric vehicle includes: a high-voltage battery having a plurality of battery cells interconnected with each other for providing a high-voltage output at battery system terminals of the battery system; and a battery disconnect element for disconnecting the high-voltage battery from at least one of the battery system terminals in the event of a fault or a collision, wherein the battery disconnect element is powered by the high-voltage battery.

[0016] The high voltage battery can be used as a traction battery for an electric vehicle, i.e. it can provide power for the propulsion of the battery electric vehicle. The high voltage battery is adapted to be connected to the electrical system of the vehicle via the battery system terminals and can provide a voltage in the HV range starting from 60 V, in particular between 60 V and 1500 V. For example, the high voltage battery can provide a voltage of 400 V and / or a current of 20 mA. The high voltage battery can therefore form part of an HV supply circuit of an electric vehicle, wherein the HV supply circuit provides power for the electric propulsion of the electric vehicle. The electric vehicle may have additional supply circuits, in particular a LV supply circuit, which, as described above, is supplied by a low voltage power supply of the electric vehicle, such as a 12 V car battery. The LV supply circuit is typically used to supply functions other than the propulsion of the electric vehicle, such as comfort functions.

[0017] The battery disconnect element according to the invention serves to disconnect the high-voltage battery from at least one of the battery system terminals in the event of a battery failure or in the event of a collision of an electric vehicle comprising a high-voltage battery as a traction battery. An overcurrent occurring in the battery can be interpreted as a malfunction of the battery. An overcurrent sensor can be provided to detect such an overcurrent. A collision of the vehicle can be detected by means of a collision sensor of the vehicle. The battery disconnect element is electrically connected to the high-voltage battery and to one or both of the battery system terminals. In particular, the battery disconnect element is electrically connected between the high-voltage battery and the battery system terminals and can be considered to be part of a battery disconnect unit (BDU) as described above. By disconnecting the high-voltage battery from at least one of the battery system terminals, in particular from the above-mentioned HV power supply circuit, the high-voltage battery is disconnected from the electrical system of the vehicle.

[0018] According to the present invention, the battery disconnect element is powered by a high-voltage battery (i.e., the traction battery of the electric vehicle). Powering the battery disconnect element by the high-voltage battery means that the energy required to trigger the battery disconnect element is provided by the high-voltage battery. For example, the battery disconnect element may include a pyrotechnic element, wherein the energy required to trigger the pyrotechnic fuse is drawn from the high-voltage battery. When the battery disconnect element is powered / triggered, the high-voltage battery is disconnected from at least one of the battery system terminals and, therefore, from the vehicle's electrical system.

[0019] Thus, with the present invention, the high-voltage traction battery of an electric vehicle is used to power / trigger a battery disconnect element (particularly a pyrotechnic element). In other words, the energy required to trigger the battery disconnect element (particularly a pyrotechnic element) is drawn from the high-voltage battery, which is intended to be electrically disconnected from the drive system in the event of a breakdown or a crash. Thus, in a sense, in the event of a breakdown or a crash, the high-voltage traction battery disconnects itself from the vehicle's electrical system, i.e., the HV power supply circuit. As long as the high-voltage battery power supply is available, sufficient power is available to trigger the battery disconnect element. Consequently, the energy required to disconnect the battery system from the vehicle's electrical system is always available and does not need to be stored in capacitors.

[0020] Compared to the prior art BDU of DE 10 2012 215 074 A1, this invention provides a simpler BDU because it does not require a capacitor. In contrast to the prior art, the present invention does not utilize the electric vehicle's LV power supply, but rather the HV power supply (i.e., the traction battery to be disconnected via the battery disconnect element) to power / trigger the battery disconnect element. Consequently, the battery system according to the present invention is less complex while still enabling safe and reliable disconnection from the vehicle's electrical system in the event of a malfunction or crash. Furthermore, due to the less complex battery system, the risk of BDU failure is lower.

[0021] According to an embodiment, the battery disconnect element comprises a pyrotechnic element, in particular a pyrotechnic fusible link. Triggering the pyrotechnic element disconnects the high-voltage battery from at least one of the battery terminals and, therefore, from the vehicle's electrical system. The pyrotechnic element allows for particularly reliable disconnection.

[0022] According to an embodiment, the battery system further comprises a transformer adapted to at least one of: convert the high voltage of the high-voltage battery into a voltage suitable for powering a battery disconnect element, and convert the current of the high-voltage battery into a current suitable for powering the battery disconnect element. Thus, using the transformer, the voltage and / or current output of the high-voltage battery can be adapted to a level suitable for powering / triggering the battery disconnect element. Thus, if the battery disconnect element includes a pyrotechnic element, the transformer can be adapted to convert the high voltage and / or current of the high-voltage battery into a voltage and / or current suitable for triggering the pyrotechnic element. In particular, the transformer can be adapted to convert 400V / 20mA of the high-voltage battery into 4V / 2A of the battery disconnect element. The transformer can also be part of the battery system's battery distribution unit (BDU).

[0023] According to an embodiment, the battery disconnect element comprises a switch and a control unit adapted to actuate the switch, wherein the actuation switch supplies power to the battery disconnect element. In particular, the actuation switch can connect the battery disconnect element to the high-voltage battery, thereby powering / triggering the battery disconnect element. Actuating the switch may mean turning on the switch, thereby turning on the drive circuit including the high-voltage battery and the battery disconnect element, so that the disconnect element can be triggered via the switch. The switch is actuated by the control unit. The control unit may be adapted to actuate the switch when a battery failure and / or a collision occurs. Corresponding sensors may be provided to detect such a failure or collision, wherein the control unit may actuate the switch based on the sensor output. The control unit may be powered by a low-voltage power supply (e.g., a 12V car battery), for example, via the above-mentioned low-voltage power supply circuit. Therefore, the control unit may be part of the low-voltage power supply circuit. The switch and / or the control unit of the switch may be part of the BDU of the battery system.

[0024] According to another embodiment, the battery system includes a backup power supply for the control unit in the event of a failure in the control unit's main power supply. As mentioned above, the control unit's main power supply can be the low-voltage power supply of the electric vehicle, such as a 12V car battery. If the main power supply fails, for example, due to a disconnection between the 12V car battery and the control unit and / or the BDU, the backup power supply is activated, thereby ensuring that the battery disconnect element is triggered.

[0025] According to another embodiment, the control unit is adapted to activate the switch for a predetermined time span, in particular for a few milliseconds. In other words, the control unit can be adapted to close the switch, thereby connecting the battery disconnect element to the high-voltage battery, and to open the switch again after the predetermined time span. The predetermined time span can be selected so that the battery disconnect element is powered long enough to be triggered. Activating the switch only for a limited time makes the system safer.

[0026] According to an embodiment, the transformer includes a first coil and a second coil, the first coil and the switch being connected in series with each other and both connected in parallel to the high-voltage battery between the two battery system terminals, and the second coil being connected to the battery disconnect element to trigger the battery disconnect element. This arrangement allows for a particularly simple BDU design.

[0027] According to another embodiment, the battery system may include a diode connected in parallel with the first winding of the transformer. The diode may be, in particular, a flyback diode. The diode may protect the switch. In particular, the diode may be used to eliminate flyback, i.e., a sudden voltage spike that occurs across the transformer, an inductive load, when the transformer's supply current is suddenly reduced or interrupted.

[0028] According to another aspect of the present disclosure, an electric vehicle is provided that includes a battery system as defined above. As explained above, the electric vehicle can be an all-electric vehicle or a hybrid vehicle. The high-voltage battery of the battery system serves as the traction battery of the electric vehicle. As explained above, the electric vehicle can include a low-voltage power supply circuit powered by the low-voltage power supply of the electric vehicle and a high-voltage power supply circuit powered by the high-voltage power supply of the battery system. Furthermore, as explained above, the low-voltage power supply can be adapted to supply power to a control unit, which can be adapted to activate a switch to supply power to the battery disconnect element.

[0029] Further aspects of the disclosure can be gathered from the dependent claims or the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Features will become apparent to those skilled in the art by describing in detail exemplary embodiments with reference to the accompanying drawings, in which:

[0031] Figure 1 is a block diagram illustrating a battery system according to an embodiment. DETAILED DESCRIPTION

[0032] Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings. The effects and features of the exemplary embodiments and their implementation methods will be described with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same elements, and redundant descriptions are omitted. For better readability, not all elements in the drawings are necessarily marked with reference numerals. In particular, in the case of redundant elements, only some of the elements may have reference numerals. However, the present disclosure can be implemented in various different forms and should not be construed as being limited to the embodiments shown herein. On the contrary, these embodiments are provided as examples so that the present disclosure will be thorough and complete and will fully convey the aspects and features of the present disclosure to those skilled in the art.

[0033] Therefore, processes, elements, and techniques that are not considered necessary for a complete understanding of the aspects and features of the present disclosure by those of ordinary skill in the art may not be described.In the drawings, the relative sizes of elements, layers, and regions may be exaggerated for clarity.

[0034] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. In addition, when describing embodiments of the present disclosure, the use of "may" refers to "one or more embodiments of the present disclosure." In the following description of embodiments of the present disclosure, terms in the singular may include plural forms unless the context clearly indicates otherwise.

[0035] It will be understood that although the terms "first" and "second" are used to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element may be named a second element, and similarly, a second element may be named a first element without departing from the scope of this disclosure.

[0036] It should also be understood that the terms “include” and “comprising” specify attributes, regions, fixed numbers, steps, processes, elements, components and combinations thereof, but do not exclude other attributes, regions, fixed numbers, steps, processes, elements, components and combinations thereof.

[0037] In the following description of the embodiments of the present disclosure, terms in the singular may include plural forms unless the context clearly indicates otherwise.

[0038] The electronic or electrical devices and / or any other related equipment or components according to the embodiments of the present disclosure described herein can be implemented using any suitable hardware, firmware (e.g., application specific integrated circuits), software, or a combination of software, firmware, and hardware. In addition, the various components of these devices can be implemented on flexible printed circuit films, tape carrier packages (TCP), printed circuit boards (PCBs), or formed on a substrate. The electrical connections or interconnections described herein can be implemented by wires or conductive elements on, for example, a PCB or another circuit carrier. The conductive elements can include metallization, such as surface metallization and / or pins, and / or can include conductive polymers or ceramics. Additional electrical energy can be transmitted via a wireless connection, for example, using electromagnetic radiation and / or light.

[0039] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It should also be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and / or this specification, and should not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0040] exist Figure 1, a battery system 10 for an electric vehicle is shown. The battery system 10 includes a high-voltage battery 12, which in turn includes a plurality of battery cells. The battery cells can be arranged in a row to form one or more battery modules. Each battery cell may include two electrode terminals connected to the electrodes of the corresponding battery cell. The battery cells can be interconnected to each other via a busbar that forms an electrical connection between the electrode terminals of two adjacent battery cells. In particular, the battery cells can be interconnected to each other in series via the busbars within the module. The high-voltage battery 12 is connected to two battery system terminals 14, 16, wherein the high-voltage battery 12 can provide its high-voltage output to the electric vehicle via these two battery system terminals 14, 16.

[0041] The battery system 10 also includes a pyrotechnic fusible link 20 as a battery disconnect element for disconnecting the high-voltage battery 12 from at least one of the battery system terminals 14, 16 in the event of a fault or crash. In particular, the pyrotechnic fusible link 20 can sever the connection between the battery system terminal 16 and the high-voltage battery 12. The pyrotechnic fusible link 20 is powered by the high-voltage battery 12, as will be explained below.

[0042] The battery system 10 further includes a transformer 22 and a switch 24. Figure 1 As shown, the transformer 22 includes a first coil 22a and a second coil 22b, wherein the first coil 22a and the switch 24 are connected in series with each other, and wherein the first coil 22a and the switch 24 are connected in parallel to the high voltage battery 12 between the two battery system terminals 14, 16. The second coil 22b is connected to the pyrotechnic fusible link 20.

[0043] The battery 12, transformer 22 and switch 24 form a drive circuit for supplying power to the pyrotechnic fusible link 20 so as to trigger the pyrotechnic fusible link 20. The pyrotechnic fusible link 20, transformer 22 and switch 24 may be part of a battery disconnect unit (BDU).

[0044] In the event of a battery system failure, or in the event of a collision involving an electric vehicle including a high-voltage battery serving as a traction battery, a control unit (not shown) activates (i.e., switches on) switch 24, thereby triggering pyrotechnic fusible link 20. Switch 24 may be activated by the control unit when it receives a crash signal provided by the vehicle's system or a signal output by the battery's overcurrent monitoring system. By activating switch 24, a drive circuit is connected, connecting pyrotechnic fusible link 20 to the high-voltage battery 12 serving as a power source, thereby triggering pyrotechnic fusible link 20. The transformer has galvanic isolation and provides the correct power to adequately trigger pyrotechnic fusible link 20. Specifically, the transformer converts the low-current, high-voltage pulses provided by the high-voltage battery 12 via its coils 22a, 22b into low-voltage, high-current pulses that are applied to pyrotechnic fusible link 20 to ignite the fusible link.

[0045] In addition, the driver circuit includes a flyback diode 26 connected in parallel to the first winding 22a of the transformer 22. The diode 26 protects the switch 24 from flyback (i.e., a sudden voltage spike across the transformer 22 when its supply current is suddenly reduced or interrupted). The flyback diode 26 may also be part of the BDU.

[0046] Thus, with the battery system of the present invention, the high-voltage battery, i.e., the traction battery of the electric vehicle, is used to power the battery disconnect element, i.e., to trigger the pyrotechnic fuse. Consequently, in contrast to the prior art, where the battery disconnect element is powered via the electric vehicle's low-voltage power supply, no capacitor is required to power the battery disconnect element. Consequently, the battery system of the present invention is less complex and presents a lower risk of component failure.

Claims

1. A battery system for an electric vehicle, comprising: a high-voltage battery having a plurality of battery cells interconnected with one another for providing a high-voltage output at a battery system terminal of the battery system; a battery disconnect element comprising a switch and a control unit adapted to activate the switch for disconnecting the high-voltage battery from at least one of the battery system terminals in the event of a fault or a crash, wherein the battery disconnect element is powered by the high-voltage battery, and A transformer adapted to be at least one of: converting the high voltage of the high voltage battery into a voltage suitable for powering the battery disconnect element, and converting the current of the high voltage battery into a current suitable for powering the battery disconnect element, The transformer includes a first coil and a second coil, the first coil and the switch are connected in series with each other and connected in parallel to the high-voltage battery between the battery system terminals, and the second coil is connected to the battery disconnect element to trigger the battery disconnect element.

2. The battery system according to claim 1, wherein: The battery disconnect element comprises a pyrotechnic element.

3. The battery system according to claim 1, wherein: Activating the switch energizes the battery disconnect element.

4. The battery system according to claim 3, wherein: The control unit is adapted to activate the switch for a predetermined time span.

5. The battery system according to claim 3 or 4, further comprising a backup power supply for the control unit in case the main power supply of the control unit fails. 6 . The battery system according to claim 1 , further comprising a diode connected in parallel to the first coil of the transformer.

7. The battery system according to claim 6, wherein: The diode is a flyback diode.

8. An electric vehicle comprising the battery system according to any one of the preceding claims. 9 . The electric vehicle according to claim 8 , comprising a low-voltage power supply circuit powered by a low-voltage power source and a high-voltage power supply circuit powered by the high-voltage battery.

10. The electric vehicle according to claim 9, wherein: The low voltage power supply is adapted to power the control unit, and the control unit is adapted to activate the switch to power the battery disconnect element.

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