Method and device for locating a battery module among several electrically interconnected battery modules of a traction battery

Abstract

Method for locating a battery module (12) among several electrically interconnected battery modules (12) of a traction battery (10), characterized by the following features: - an electrical potential is measured at each of the battery modules (12) in a timely manner with respect to a potential reference (14) common to the battery modules (12), - electrical voltages between the battery modules (12) are calculated subtractively from the potentials, - a positional relationship of the battery modules (12) is derived from the voltages, - by means of a module controller (16) uniquely identified within the traction battery (10), a voltage drop across the battery module (12) to be located is retrieved and - Based on the retrieved voltage and the calculated voltages, the battery module (12) is located within the traction battery (10) according to the positional relationship.

Description

[0001] The present invention relates to a method for locating a battery module among several electrically connected battery modules of a traction battery. The present invention further relates to a corresponding device, a corresponding computer program, and a corresponding storage medium. State of the art

[0002] Control systems for the modules of a traction battery in an electric vehicle are known. Each module can have a module controller that monitors data such as temperature and voltage of the individual cells and sends these values ​​to a central battery controller via a bus system.

[0003] When module controllers communicate with the battery controller, they can use a unique address, identification (ID), or code. This address, ID, or code can be permanently and uniquely assigned to a module location and designed so that no two module controllers with the same address, ID, or code can occur on a battery controller bus in a vehicle. Known solutions achieve this, for example, with an address that is unique among all existing or produced modules; the MAC address in computer networks can serve as a model.

[0004] US 2010 0182 154 A1 describes a battery control system in which each battery module has a module controller that determines cell data such as voltage and temperature and sends it to a central battery controller via a bus system. The individual controllers send ID information to the battery controller via a second bus system. The combination of this data and the ID information determines the installation location of a module.

[0005] US 2014 0272 500 A1 describes the possibility of determining the location of faulty battery modules based on their electromagnetic activity. Controllers on the modules are supposed to detect the electromagnetic activity and transmit it to a central battery controller via a bus system.

[0006] US 2010 0250 043 A1 describes a rechargeable battery system. It focuses in particular on the measurement of individual cell data such as temperature and voltage.

[0007] US 2012 0244 398 A1 describes a battery system in which individual module controllers are connected via a bus system and can exchange data with each other.

[0008] From US 2014 0045 004 A1 a battery control system is known in which a controller is located on each module, which measures the voltage of the module and sends it to a central battery controller via a bus system.

[0009] US 2014 0062 385 A1 describes a battery security system designed to report unauthorized access to a battery module. For this purpose, a monitoring unit is attached to each battery module, which sends information via a bus system to a central control unit. Disclosure of the invention

[0010] The invention is based on the realization that for a trouble-free replacement of individual cell modules, the battery controller, any other central controller of the vehicle, or the on-board diagnostics (OBDC or OBD) must identify the module. In particular, if the battery controller detects a problem, failure, or any other event with a cell module, the module must be identified and replaced. A conventional battery controller can link the problem to an address, label, or code of the cell module, but not to its installation location.

[0011] The invention therefore provides a method for locating a battery module among a plurality of electrically connected battery modules of a traction battery, a corresponding device, a corresponding computer program and a corresponding storage medium according to the independent claims.

[0012] According to the invention, the address, ID, or code of the cell module thus indicates the installation location. To achieve this, the modules do not need to be individually programmed for each installation location in the battery – electronically or mechanically, for example, to prevent incorrect installation at the factory – which would result in a large number of different components and low production runs, nor do they need to be laboriously programmed individually after assembly so that the installation location of the respective module can be matched with a corresponding address, ID, or code.

[0013] For this purpose, each cell module – that is, its electronics – assigns its own electrical position within the network of all cell modules, or a central controller assigns an electrical position of the corresponding cell module to each address, ID, or code. This also means that the physical location in the battery box is known without the need for a laborious comparison – e.g., in a table – between the cell module address, ID, or code and the corresponding physical location in the battery. However, this would require a high-voltage cable, which is prone to errors, to be run across the battery to each cell module to measure the electrical potential of the respective cell module. The high voltage that this cable assumes, for example, relative to the conductors of the communication bus in the battery, but also to any battery connection, can lead to insulation faults and short circuits.

[0014] According to the invention, the electrical situation can be determined by measuring the electrical potential, for example, of the negative terminal of the battery. More generally, the electrical potential of any point in the circuit can also be measured—provided it is not generated by a voltage converter that produces higher voltages than the cell module voltage—since each cell module spans a fixed potential range that generally does not overlap with other cell modules.

[0015] However, it should be noted that the high-voltage system, and thus also the battery module, are generally galvanically isolated from the rest of the battery. The common reference point for measuring the electrical potentials of each module is therefore crucial.

[0016] A specialist might be tempted to provide each cell module with an electrical potential reference point via a cable connected, for example, to the negative terminal of the entire battery. This would generate a reference from the battery itself and circumvent the problem of galvanic isolation from the low-voltage system. However, this would require a high-voltage cable, which is prone to errors, to be routed across the battery to each cell module to measure the electrical potential of the respective cell module. In the topmost battery, the voltage can sometimes reach as high as 800 V.

[0017] The dangers of such an approach are advantageously avoided by the invention. In particular, it dispenses with an additional high-voltage line, whose insulation damage could lead to serious accidents and cause arcs to ignite.

[0018] Further advantageous embodiments of the invention are specified in the dependent patent claims. Short description of the drawings

[0019] An embodiment of the invention is illustrated in the drawings and is described in more detail below. Fig. 1 shows the simplified circuit diagram of a first embodiment. Fig. 2 shows the circuit diagram of a second embodiment of the invention. Embodiments of the invention

[0020] The not unproblematic measurement of the electrical potential of each cell module can be accomplished according to the invention in several ways, the first of which is now based on the Fig. 1. As an example, only a single battery module 12 is shown, which is, however, connected to the previous module 30 and the next module 32 via high-voltage cables.

[0021] The invention takes advantage of the fact that, despite the galvanic isolation in a typical traction battery 10, there is at least one capacitive coupling to the low-voltage side, on which, for example, the low-voltage on-board network is operated and, in particular, also the bus system 20, which provides communication between each battery module 12 equipped with a corresponding bus transceiver 34 and the battery controller and / or other modules 36.

[0022] Since, according to the invention, all electrical potential measurements are carried out essentially simultaneously, a wide variety of points on the low-voltage side represent a sufficient electrical potential reference 14.

[0023] The voltage between the battery modules 12 can be determined in the next step by pairwise subtraction of the electrical potentials of all battery modules 12. Battery modules 12 whose voltage values ​​form the smallest difference can, as a first approximation, be considered to be electrically directly adjacent.

[0024] Furthermore, the module controller 16 or the battery controller generally also measures the temperature and voltage of all individual cells 18 by means of corresponding measuring lines 22 and temperature sensors 24 and, together with the potential information, can precisely determine the electrical interconnection of the battery modules 12.

[0025] Each battery module 12 can perform this potential measurement for its own potential and exchange the value electronically with the other battery modules 12 and / or send it to the battery controller.

[0026] Since an exactly simultaneous measurement is not always desired or cannot be maintained, particularly under the conditions encountered in vehicle technology, a low-pass filter 28 is preferably used, which smooths the voltage difference between the own electrical potential and the reference potential 14 on the low-voltage side with a slow time constant, so that the simultaneity condition mentioned above is softened or becomes completely obsolete.

[0027] The choice of the reference potential is crucial for implementation: Since in a typical traction battery 10 intentionally few electrical parts of the low-voltage network are available, the body is also intentionally shielded and a separate electrical line with reference potential is problematic, this choice proves to be essential to the invention.

[0028] Commercially available battery modules 12 typically feature galvanic isolation 38. In rare cases, this is located closer to the battery controller. At this isolation 38, the electronic bus system 20 for communication with other battery modules 12 and / or the battery controller connects to the respective battery module 12. At this point, a measurement of the potential of the battery module 12 against that of the bus system 20 can be advantageously implemented.

[0029] Fig.Figure 2 illustrates a particularly advantageous embodiment of the invention, which takes advantage of the fact that in numerous electric vehicles, an insulation monitor 40 continuously monitors whether a conductive electrical connection exists between one or more high-voltage systems and the low-voltage side—represented, for example, by the body—and thus whether the electrical isolation 38 is damaged. Contrary to an obvious misconception, however, commercially available insulation monitors 40 sometimes cancel out the assumed galvanic isolation to such an extent that the measurement within the meaning of the invention is enabled.

[0030] Many insulation monitors 40 use one of the following two principles, both of which enable the potential measurement according to the invention: Either the insulation monitor 40 establishes a fixed—but extremely high-resistance and thus usually undetected—potential connection between the high-voltage and low-voltage parts, and detects a violation of the potential separation 38 by requiring the insulation monitor 40 to supply current to maintain this potential connection. This potential connection can also vary over time, for example, following a sinusoidal waveform. More frequently, however, the low-voltage parts are maintained close to the middle of the potentials of the high-voltage side with high temporal stability.

[0031] Alternatively, the insulation monitor 40 can allow a very small current, usually varying over time, to flow from the low-voltage side to the high-voltage side and / or back and measure the potential relationship to check whether a conductive connection exists between the two.

[0032] In both cases, the insulation monitor 40 generates the stable potential reference 14 for the measurement according to the invention. In particular, this also defines the potential of the bus system 20, which represents a preferred potential reference 14 for the measurement.

[0033] Regardless of the choice of potential reference 14, the following considerations apply to the proposed measurement: Since A / D inputs of the module controller 16, which can be used for this purpose, do not allow high voltages and the potential separation 38 of the battery modules 12 from the low-voltage part must not be undermined, the electrical potential of a battery module 12 can be measured in several ways.

[0034] For example, the differential voltage between the potential and the potential reference 14 is reduced to a low voltage value using a resistance divider. To prevent the resistance divider from triggering the insulation monitor 40, it should be designed with such a high resistance that all cross currents of all potential measurements on individual cells 18 of the battery modules 12 are significantly lower than the trigger current threshold of the insulation monitor 40.

[0035] It is advantageous to use an isolation amplifier or an analog signal isolator for the measurement. This allows the galvanic isolation to be maintained.

[0036] Furthermore, a low-pass filter 28 is recommended because the electromagnetic interference can be very high due to the high currents in the traction battery 10.

[0037] Furthermore, if the electrical bus system 20, which actually serves for communication with the other battery modules 12 and / or the battery controller, is used as a potential reference 14, the following aspects should be considered: Typically, it is a differential bus system 20 with at least two lines to reduce interference.

[0038] Preferably, not only one line of the bus system 20, but the average value of all lines should be calculated and used as potential reference 14.

[0039] Since the information about the respective electrical potential of each battery module 12 is sent from the battery module 12, along with its own address, ID, code, or the like, and typically the voltages of the individual cells 18, to the battery controller and / or other controllers such as the OBD unit, this unit also knows the respective potentials and their assignment to the addresses, IDs, or codes. Using the information about the potentials, the complete electrical wiring of the power unit can be determined.

[0040] Since the electrical wiring of the power section in the traction battery 10 is predetermined by the design of the traction battery 10, the spatial position of the battery modules 12 with specific addresses, IDs or codes is known without ever having to perform a complex manual comparison of a table of addresses, IDs or codes with the spatial locations of the battery modules 12.

[0041] Since the information about the voltages of the individual cells 18 and the potentials can be combined, inconsistencies can also be identified. For example, the potential of one battery module 12 may indicate a significant deviation. However, since the potentials of the remaining battery modules 12 are likely to be distributed approximately evenly and equidistantly across the voltage of the entire traction battery 10, a deviation that is significantly higher than the voltages of the individual cells 18 can be detected.

[0042] Furthermore, the information can be recorded over time. Since the positions are known when the system is first switched on and a position detection is performed, and it cannot be assumed that a different position exists without opening the vehicle, even faults in individual cells 18 of the battery modules 12 can be detected if a plurality of voltage sensors fail.

[0043] For this purpose, the electrical potential of the most electrically negative point of the interconnected individual cells 18 in a battery module 12 is preferably determined. The latter most negative point, usually also the negative pole of the respective battery module 12, is also used in a typical traction battery 10 as the ground potential of any module controller 16 integrated in the battery module 12.

[0044] Alternatively, any other point, for example taps on one of the individual cells 18, could be used, since each battery module 12 comprises its own specific potential range, which usually does not correspond to the specific potential ranges of the neighboring battery modules 12.

Claims

[1] Method for locating a battery module (12) among several electrically connected battery modules (12) of a traction battery (10), characterized by following features: - an electrical potential is measured promptly at each of the battery modules (12) with respect to a potential reference (14) common to the battery modules (12), - electrical voltages between the battery modules (12) are calculated subtractively from the potentials, - a positional relationship of the battery modules (12) is derived from the voltages, - by means of a module controller (16) clearly identified within the traction battery (10), a voltage drop across the battery module (12) to be located is retrieved and - based on the retrieved voltage and the calculated voltages, the battery module (12) is located according to the positional relationship within the traction battery (10). [2] Method according to claim 1, characterized by following features: - the battery modules (12) each comprise several galvanic individual cells (18) and - the voltage drop across the battery module (12) is retrieved by retrieving the voltage of each individual cell (18) of the battery module (12) by means of the module controller (16). [3] Method according to claim 1 or 2, characterized by following features: - the module controller (16) is one of several module controllers (16) connected to the traction battery (10) via a bus system (20), each of which is assigned to a battery module (12), and - the bus system (20) defines the potential reference (14). [4] Method according to claim 3, characterized by following features: - the bus system (20) further connects the battery modules (12) to a battery controller of the traction battery (10) and - the calculation of the voltages, the derivation of the positional relationship, the retrieval of the voltage or the location of the battery module (12) is carried out by the battery controller. [5] Method according to claim 3 or 4, characterized by following features: - the potential is measured by a voltmeter (26) assigned to the respective battery module (12) and - the voltmeter (26) reports the potential to the respective module controller (16) via a low-pass filter (28). [6] Method according to one of claims 3 to 5, characterized by following features: - an insulation monitor (40) monitors a galvanic potential separation (38) between the battery module (12) and the bus system (20) and - the insulation monitor (40) defines the potential reference (14). [7] Method according to one of claims 1 to 6, characterized bythat the positional relationship of the battery modules (12) is stored and retrieved as needed to locate another battery module (12) among the battery modules (12). [8] Device, in particular for carrying out a method according to one of claims 1 to 7, characterized by following features: - means for measuring an electrical potential with respect to a potential reference (14) common to several battery modules (12) of a traction battery (10) which are electrically connected to one another, at each of the battery modules (12), - means for subtractively calculating electrical voltages between the battery modules (12) from the potentials, - means for deriving a positional relationship of the battery modules (12) from the voltages, - means for retrieving a voltage drop across a battery module (12) to be located among the battery modules (12) by means of a module controller (16) clearly identified within the traction battery (10) and - Means for locating the battery module (12) according to the positional relationship within the traction battery (10) based on the retrieved voltage and the calculated voltages. [9] Computer program which is designed to carry out all the steps of a method according to one of claims 1 to 7. [10] A machine-readable storage medium having stored thereon a computer program according to claim 9.

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