Method for operating a wireless network of a battery management system

Abstract

A primary network node of a master BMS unit (5) of the battery management system, BMS, and a respective secondary network node of a slave BMS unit (30) of the BMS are configured to communicate with each other using a predetermined wireless communication protocol. A matrix of connection quality parameter values ​​is determined depending on provided measured values, wherein the provided measured values ​​are each representative of a signal quality for a signal received by the primary network node in a respective frequency channel from a respective secondary network node. The frequency channels are classified depending on the connection quality parameter values ​​determined for the frequency channels, and the frequency channels assigned to a first group are used for transmission.

Description

[0001] The present disclosure relates to a method and a corresponding control unit for operating a battery management system. Furthermore, the present disclosure relates to a battery control system and a battery system. Furthermore, the disclosure relates to a computer program and a computer-readable storage medium.

[0002] Battery manufacturers in the electric vehicle sector strive to achieve the highest possible energy density in their batteries, especially traction batteries, to enable maximum range for customer vehicles. As energy density increases, so does the importance of battery management systems for monitoring, balancing, and hazard prevention associated with overvoltage and overtemperature.

[0003] The traction batteries of electric vehicles currently provide nominal voltages between 400V and 800V. The batteries are typically organized into battery modules – groups of cells – that are monitored and controlled by dedicated battery management circuits (BMICs). Typically, such a battery management circuit can currently monitor 16 to 24 cells connected in series.

[0004] One of the main tasks of a battery management circuit is the periodic measurement of cell voltages, temperatures, and other parameters, which are transmitted to a central control unit of the battery management system. The central control unit determines, among other things, the battery's state of charge (SOC) and / or state of health (SoH). In the context of the battery management system, the battery management circuits are relevant for functional safety.

[0005] Since system costs and flexibility in battery configuration are high priorities for manufacturers, systems are increasingly being developed that transmit safety-relevant battery data wirelessly. Wireless data transfer can achieve significant savings in cabling, connectors, and, in particular, in the galvanic isolation of components.

[0006] Electromagnetic interference is becoming increasingly common in electric vehicles. Components such as inverters, DC / DC converters, and charging units have the potential to interfere with the spectrum of a wireless BMS. Due to the installation conditions in a battery, especially in the traction battery of an electric vehicle, with extreme metallic reflection spaces, current pico-networks in batteries struggle with interference effects, frequency detuning, multipath propagation, and standing wave effects.

[0007] An object to be achieved by the invention is therefore to provide a method and a corresponding control unit which enables improved wireless data transmission between a master battery management system unit and respective slave battery management system units.

[0008] The problem is solved by the features of the independent patent claims. Advantageous developments of the invention are characterized in the subclaims.

[0009] According to a first and second aspect, the object is achieved by a method and a corresponding control unit for operating a wireless network of a battery management system (BMS) for a battery, in particular a traction battery of a vehicle. The control unit has at least one processor and at least one program memory and is configured to execute the method.

[0010] The battery preferably comprises a plurality of battery modules connected in series and / or parallel. The battery modules preferably each have a plurality of battery cells connected in series and / or parallel.

[0011] The BMS comprises a master BMS unit with a master control unit and a primary network node coupled to the master control unit. Furthermore, for a given number of battery modules of the battery, the BMS comprises a slave BMS unit each, which has a slave control unit and a secondary network node coupled to the slave control unit.

[0012] The BMS may have a slave BMS unit for each battery module, which is arranged, for example, on the battery module or on a section of a battery mounting frame that is adjacent to the respective battery module.

[0013] The primary network node and the respective secondary network node are configured to communicate with each other using a predetermined wireless communication protocol, wherein the communication protocol uses a time-based main frame to transmit data and a number of K frequency channels are available for data transmission.

[0014] For example, the wireless BMS network is a pico network.

[0015] The procedure includes the following steps: In step a1), a matrix of connection quality parameter values ​​is determined based on the provided measured values. The matrix includes a connection quality parameter value for at least some of the wireless communication connections between the primary network node and a respective secondary network node for at least some of the frequency channels. The provided measured values ​​are each representative of a signal quality for a signal received by the primary network node in a respective frequency channel from a respective secondary network node.

[0016] In step b), the frequency channels are classified, with the respective frequency channel being assigned to a first group if the connection quality parameter values ​​determined for the respective frequency channel satisfy a predefined condition. If the connection quality parameter values ​​determined for the respective frequency channel do not satisfy the predefined condition, the respective frequency channel is assigned to a second group.

[0017] An instruction is provided for the master BMS unit, which comprises the usable frequency channels of the first group and which causes the master BMS unit, during operation, in particular during active operation of the BMS in which the BMS controls and / or monitors charging or discharging of the battery, to determine a frequency channel from the first group for a respective connection event, in particular for the transmission of a main frame, depending on a predetermined rule or a predetermined algorithm, and the primary network nodes and the secondary network nodes to send data in the respective main frame in the determined frequency channel. In particular, the frequency channel is determined again for each transmission of a main frame.

[0018] The primary network node and the secondary network nodes are configured to transmit data using frequency hopping. In this method, the information to be transmitted is distributed sequentially across multiple frequency channels. Only one frequency channel is used at a time.

[0019] Steps a1), b) and c) are carried out, for example, by a central processing unit that is coupled to the master BMS unit.

[0020] In an established network, particularly a piconet, formed by the master BMS unit and the slave BMS units assigned to the master BMS unit, the frequency sequence is specified by the master BMS unit. The master BMS unit is specifically designed to determine the respective frequency channel using a sequence of pseudorandom numbers. This randomness minimizes channel occupancy overlap when multiple networks are active, as it reduces the likelihood of channel collisions.

[0021] The method has the advantage that the frequency hopping method is only used in conjunction with frequency channels where sufficient transmission quality is guaranteed. The grouping of the frequency channels takes into account static boundary conditions, in particular the respective installation position and installation situation of the respective battery modules.

[0022] Due to the design of a wireless network of a battery management system, the installation situation of the slave BMS units (complex, metallic reflection chambers) can lead to significant differences in the radio connection between the primary network node of the master BMS unit and the secondary network nodes of the slave BMS units. In particular, in star network topologies, secondary network nodes with a large distance from the primary network node or very disadvantageous installation positions, sometimes even due to double battery layers, often have significantly worse link budgets and low indicator values ​​for the received field strength (in English Received Signal Strength Indicator Values, or RSSI values). Interference effects, frequency detuning, multipath propagation, and standing wave effects lead to a further deterioration of data transmission.

[0023] The method according to the invention enables "weak" frequency channels in the wireless network to be identified and "blacklisted" or "removed from a whitelist" used for frequency hopping. This explicit masking of "weak" frequency channels compensates for installation-related disadvantages and reduces the influence of narrowband stationary interferers.

[0024] In at least one embodiment according to the first and second aspects, the BMS has at least one further master BMS unit or at least one auxiliary master BMS unit, and step a1) is additionally carried out for the at least one further master BMS unit or the at least one auxiliary master BMS unit, and in a step a2), the slave BMS units are each assigned to one of the at least two master BMS units or either the master BMS unit or the at least one auxiliary master BMS unit depending on the determined connection quality parameter values ​​in order to form sub-networks, and steps b) and c) are each carried out for the sub-networks, wherein the at least one auxiliary master BMS unit comprises a slave BMS unit which is additionally designed to perform one or more functions of a master BMS unit.

[0025] In at least one embodiment according to the first and second aspects, at least steps a1) and b) are therefore performed in a calibration phase of the BMS. This allows frequency channels to be excluded from transmission in advance, and dynamic adaptation for the frequency hopping method during operation of the vehicle or the BMS can be simplified.

[0026] In the calibration phase, the link quality parameter values ​​are preferably determined for all communication links between the primary network node and the respective secondary network nodes for all frequency channels.

[0027] In at least one embodiment according to the first aspect, the BMS comprises at least one further master BMS unit or at least one auxiliary master BMS unit, and step a1) is additionally carried out for the at least one further master BMS unit or the at least one auxiliary master BMS unit. In a step a2), which is carried out in particular after step a1), the slave BMS units are each assigned to one of the at least two master BMS units or to the master BMS unit or the at least one auxiliary master BMS unit, depending on the determined connection quality parameter values, in order to form subnetworks. Furthermore, steps b) and c) are each carried out for the subnetworks.

[0028] The at least one auxiliary master BMS unit comprises a slave BMS unit which is additionally designed to perform one or more functions, or even all functions, of a master BMS unit.

[0029] The formation of subnetworks has the advantage that the first group of frequency channels can be better adapted to the spatial boundary conditions.

[0030] In at least one embodiment according to the first and second aspects, the primary network node and the secondary network nodes are configured to additionally transmit the data using frequency spread. Frequency spread converts a narrowband signal into a signal with a wider bandwidth than necessary for information transmission. The transmission energy, which was previously concentrated in a smaller frequency range, is distributed over a larger frequency range.

[0031] In at least one embodiment according to the first and second aspects, the connection quality parameter comprises a Received Signal Strength Indicator (RSSI).

[0032] In at least one embodiment according to the first aspect and second aspect, during active operation of the BMS, in which the BMS controls and / or monitors charging or discharging of the battery, additional connection quality parameter values ​​are provided or received, and steps a1) and b) are performed again depending on the additional connection quality parameter values. Alternatively, steps a1), a2), and b) can also be performed again.

[0033] The connection quality parameter values ​​may include values ​​of at least one connection quality parameter from the following set: data throughput, error rate, repetition rate and an indicator of the received field strength determined in one cycle.

[0034] This has the advantage that if temporary interference from other system-internal components, in particular for example from other vehicle components such as inverters, DCDC converters, on-board chargers, ...) or from outside (e.g. due to interference from other networks, e.g. Bluetooth, WiFi, mobile communications, ...) affects individual frequency channels or frequency channel groups, the "white list" or the first group can be dynamically optimized or adapted depending on the interference.

[0035] In at least one embodiment according to the first and second aspects, after a predetermined period of time or when the first group falls below a minimum number of frequency channels, steps a1), b) and c) are carried out again for at least some of the respective wireless communication connections between the primary network node and a respective secondary network node for at least some of the frequency channels of the second group.

[0036] The BMS thus uses a frequency hopping method in which the frequency channels to be used can be adapted to the given spatial boundary conditions in the battery and to the dynamic additional interference sources of the electric drive (motor, inverter, etc.) and also to interference from other wireless networks.

[0037] According to a third aspect, the object is achieved by a battery system having a plurality N of battery modules, each comprising one or more battery cells. Furthermore, the battery system comprises a master BMS unit with a master control unit and a primary network node coupled to the master control unit. Furthermore, for each of the N battery modules, the battery system comprises a slave BMS unit, each having a slave control unit and a secondary network node coupled to the slave control unit. The respective slave BMS unit is connected to the battery module.

[0038] The primary network node and the respective secondary network node are configured to communicate with each other using a predetermined wireless communication protocol, wherein the communication protocol uses a time-based main frame to transmit data and a number of K frequency channels are available for data transmission.

[0039] According to a fourth aspect, the object is achieved by a computer program comprising instructions which, when the program is executed by a control computer, cause the control computer to carry out the method according to the first aspect.

[0040] For the purposes of this document, the reference to such a computer program is synonymous with the term "a program element" and / or "a software module" and / or "a computer program product" that contains instructions for controlling the control computer to coordinate the operation of the battery system or the method for operating a wireless network of a battery management system in a suitable manner to achieve the effects associated with the method according to the invention. The computer program can be implemented as computer-readable instruction code in any suitable programming language, such as JAVA, C++, etc.

[0041] The control computer includes a processor and a program memory. Alternatively, the program memory may be associated with the control computer. The processor may include a central processing unit (CPU). The processor may be a general-purpose processor, a microprocessor, a microcontroller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or the like.

[0042] According to a fifth aspect, the above-mentioned object is achieved by a computer-readable medium having instructions which, when executed by a control computer, cause the control computer to carry out the method according to the first aspect.

[0043] The computer program can be stored on a computer-readable storage medium (CD-ROM, DVD, Blu-ray disk, removable drive, volatile or non-volatile memory, in particular random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), and / or flash memory. The storage medium can be a memory built into the processor, a memory arranged externally of the processor on a module, or a portable memory. The memory is configured to store associated program instructions and associated data.

[0044] Furthermore, the computer program may be made available on a network such as the Internet, from which it can be downloaded by a user when required.

[0045] Advantageous embodiments of the first and second aspects also apply to the third, fourth and fifth aspects.

[0046] Further advantageous embodiments are disclosed in the appended claims and the following description of embodiments with reference to the appended figures.

[0047] The description of the subject matter presented herein is not limited to the specific individual embodiments. Features of different embodiments may be combined with one another—where technically feasible—to form further embodiments. For example, variations or modifications described with respect to one embodiment may also be applicable to other embodiments, unless otherwise stated.

[0048] They show: Fig. 1 a schematic diagram of a battery with a wireless battery management system, Fig. 2 an exemplary communication frame format for wireless transmission, Fig. 3 an exemplary flowchart for a program for executing a method for operating a wireless network of a battery management system and Fig. 4 exemplary magnitude frequency responses of slave BMS units at selected installation positions in relation to the master BMS unit.

[0049] In the figures, the same reference numerals are used for elements with essentially the same function, but these elements do not have to be identical in all details.

[0050] Fig. 1 shows an exemplary schematic diagram of a battery 1 comprising a wireless battery management system (BMS) and a battery pack 5. The battery 1 may comprise one or more such battery packs 5.

[0051] The Fig. The battery 1 shown in Figure 1 comprises, by way of example, a battery unit 5. The battery 1 can be used for a variety of electrically operated devices, such as in particular in an electrically powered vehicle. The battery unit 5 comprises a plurality of battery modules 20 connected in series and / or in parallel. Each battery module 20 can comprise a plurality of battery cells that are electrically connected in series and / or in parallel.

[0052] The wireless BMS comprises a master BMS unit 10 and a plurality of slave BMS units 30. The master BMS unit 10 is configured, for example, to assign different identification information to the plurality of slave BMS units 30 by interacting with a central processing unit 40. The wireless BMS may comprise the central processing unit 40, or the central processing unit 40 may be assigned to the wireless BMS.

[0053] The master BMS unit 10 comprises, in particular, a control unit with a memory and a communication unit with an antenna. The communication unit of the master BMS unit 10 is referred to below as the primary network node.

[0054] The memory of the control unit of the master BMS unit 10 is particularly designed to permanently or temporarily store at least part of the data transmitted by the central processing unit 40, for example via a wired communication mode, or the data transmitted wirelessly by the respective slave BMS units 30.

[0055] The memory may be physically separated from the control unit of the master BMS unit 10 and may be integrated on a chip with the control unit of the master BMS unit 10.

[0056] The antenna of the master BMS unit 10 and the communication unit of the master BMS unit 10 are operatively connected to each other. The primary network node comprises a radio transmitting unit and a radio receiving unit. The primary network node is preferably configured to receive and transmit carrier frequency modulated signals. In particular, the primary network node is configured to receive carrier frequency modulated signals from and transmit them to the respective slave BMS units 30.

[0057] The master control unit of the master BMS unit 10 includes at least one processor and is connected to the memory and the primary network nodes of the master BMS unit 10. The master control unit of the master BMS unit 10 is configured to control the overall operation of the master BMS unit 10. Furthermore, the master control unit is configured, for example, to determine a state of charge (SOC) and / or a state of health (SOH) of each of the battery modules based on the sensing information received from the slave BMS units 30. Additionally, the master control unit may be configured to provide information for controlling the charging, discharging, and / or balancing of each of the battery modules based on the calculated SOC and / or SOH and to initiate wireless transmission to at least one of the plurality of slave BMS modules 30 via the primary network node.

[0058] Each processor included in the master control unit may optionally include a microprocessor, a microcontroller, an application-specific integrated circuit (ASIC), chipsets, logic circuitry, a register, a communications modem, and a data processing device known in the art for executing various control logic.

[0059] At the Fig. 1, the battery unit 5 comprises, for the sake of simplicity, four battery modules 20, and the wireless BMS comprises four slave BMS units 30. Preferably, the number of slave BMS units 30 corresponds to the number of battery modules 20 in the battery unit 5. The respective slave BMS unit 30 is electrically coupled to one of the battery modules 20. For example, the first slave BMS module 30_1 is electrically coupled to the first battery module 20_1, the second slave BMS module 30_2 is electrically coupled to the second battery module 20_2, the third slave BMS module 30_3 is electrically coupled to the third battery module 20_3, and the fourth slave BMS module 30_4 is electrically coupled to the fourth battery module 20_4.

[0060] The respective slave BMS unit 30 is configured, for example, to detect or monitor multiple operating variables, e.g., a voltage, a current, and a temperature of the battery module 20 to which the slave BMS unit 30 is electrically connected, and to execute a variety of control functions, e.g., charging, discharging, balancing, to adjust the operating variables of the battery module 20. For example, each control function can be executed directly by each slave BMS unit 30 based on the detected operating variables of the battery module 20 or according to a command from the master BMS unit 10.

[0061] Each slave BMS unit 30 includes a slave control unit with a memory and a communication unit with an antenna. The communication unit of the slave BMS unit 10 is hereinafter referred to as the secondary network node. The memory may be physically separated from the slave control unit or may be integrated on a chip together with the control unit.

[0062] The respective secondary network node comprises a transmitting and receiving unit and is configured to transmit data to or receive data from the master BMS unit 10 or the primary network node. Optionally, the respective secondary network node is configured to transmit data to and receive data from other secondary network nodes and thus to other slave BMS units 30.

[0063] The slave control unit of the respective slave BMS unit 30 includes at least one processor and is operably connected to the memory and the secondary network node of the slave BMS unit 30. The slave control unit is configured to manage the overall operation of the slave BMS unit 30.

[0064] The respective slave BMS unit 30 may include a sensing unit configured to detect the state of the battery module 20. For example, the sensing unit 150 may include at least a voltage measuring circuit for detecting the voltage of the battery module 20, a current measuring circuit for detecting the current of the battery module 20, and a temperature detecting circuit for detecting the temperature of the battery module 20.

[0065] The slave control unit of the respective slave BMS unit 30 provides the secondary network node of the slave BMS unit 30 with sensing information indicating the state of the battery module 20 detected by the sensing unit. Accordingly, the secondary network node of the respective slave BMS unit 30 can transmit a wireless signal representing the sensing information to the master BMS unit 10.

[0066] The primary network node and the secondary network nodes are configured to communicate with each other using a predetermined wireless communication protocol, wherein the communication protocol uses a time-based main frame to transmit data and a number of K frequency channels are available for data transmission.

[0067] Fig. Figure 2 shows an example of such a communication frame format. The communication frame format includes the time-based main frame SF1, SF2. The main frame SF1, SF2 has a number M of time slots. Each of the time slots, in turn, has a specific frame format. Each of the time slots is configurable, for example, based on the end application of the wireless battery management system.

[0068] The communication frame format further comprises a number K of frequency channels which can be used for transmitting data according to the main frame SF1, SF2.

[0069] For example, in a normal operating mode of the battery management system, a first time slot of the main frame SF1, SF2 includes a downlink frame 1_DL, 2_DL which is used by the primary network node to send data to the secondary network nodes.

[0070] For example, during a first main frame SF1, the primary network node transmits the DL frame 1_DL on a first frequency f1 during the first time slot. During the first time slot, at least one of the secondary network nodes receives the DL frame 1_DL. The DL frame 1_DL can be transmitted by the primary network node as a broadcast, in which data packets are transmitted from one point to all participants in a communications network. Alternatively, the DL frame 1_DL can be transmitted by the primary network node as a unicast. Unicast refers to the addressing of a message to a single recipient.

[0071] The second time slot of the first main frame SF1 comprises, for example, a first uplink frame 1_UP1, which is used by a first secondary network node to send data to the primary network node and / or to the other secondary network nodes.

[0072] The first secondary network node transmits the first UL frame 1_UP1 on the first frequency f1 during the second time slot in response to receiving the DL frame 1_DL transmitted by the primary network node. A second secondary network node transmits the second UL frame 1_UL2 in the first frequency channel at the first frequency f1 during the third time slot in response to receiving the DL frame 1_DL from the primary network node. A third secondary network node transmits the third UL frame 1_UL3 in the first frequency channel during the fourth time slot in response to receiving the DL frame 1_DL from the primary network node. The (M-1)th secondary network node transmits the (M-1)th UL frame 1_UL M-1 in the first frequency channel during the Mth time slot in response to the receipt of the DL frame 1_DL from the primary network node. In this example, the main frame ends at the end of the Mth time slot.

[0073] The transmission cycle, or the length of the main frame, depends, for example, on the number of secondary network nodes. The master BMS control unit or the control unit determines the main frame interval based on the number of secondary network nodes. Accordingly, for a given network node, the total number of time slots in the communication time interval is the sum of the number of slave BMS units and the number of DL slots of the primary network node.

[0074] Preferably, the primary network nodes and secondary network nodes are configured to use a frequency hopping method. In the frequency hopping method, the network nodes change the carrier frequency or frequency channel based on a hopping sequence specified by the master control unit. Preferably, a change in the carrier frequency or frequency channel occurs after each transmission of one of the main frames.

[0075] To reduce interference caused by reflections in the battery housing, the frequency hopping method can be adapted. For example, during calibration of the BMS system, individual frequency channels or groups of adjacent frequency channels from the transmission band where the signal quality is very poor are identified. These individual frequency channels or groups of frequency channels are then not used for transmission.

[0076] Fig. 3 shows an exemplary sequence program for a program for executing a method for operating a wireless network of a battery management system.

[0077] The program is executed, for example, by a processor of a control unit that acts as the higher-level processing unit for the BMS. Alternatively, the master control unit of the master BMS unit can include the control unit.

[0078] In a step S01 the program is started and, for example, program variables are initialized.

[0079] In a step S03, a matrix of connection quality parameter values ​​is determined based on the provided measured values. A connection quality parameter value is determined for at least some of the wireless communication connections between the primary network node and the respective secondary network nodes for at least some of the frequency channels.

[0080] If the network has N secondary network nodes and K frequency channels are available, and the link quality parameter values ​​are determined for all secondary network nodes and all frequency channels, a matrix with NxK elements results. If the number of frequency channels to be considered is reduced to Kz and the number of connections from the secondary network nodes to the primary network node to be considered is reduced to Ny, a matrix with (Ny)x(Kz) results.

[0081] The measured values ​​provided are each representative of a signal quality for a signal received by the primary network node in a respective frequency channel from a respective secondary network node.

[0082] For example, the master control unit or the central processing unit determines an RSSI (RSSI = Radio Signal Strength Indicator) for each frequency channel for each secondary network node.

[0083] For this purpose, a measurement of the signal strength is performed on as many frequency channels as possible, for example, the 2.45 GHz ISM band (2.400 GHz to 2.484 GHz). The primary network node, for example, has a transceiver designed to determine and output RSSI values ​​(RSSI = Radio Signal Strength Indicator). For example, for a connection between the primary network node and a first secondary network node, a 2 MHz wide frequency channel is measured for a duration of 20 µs, followed by a switch to another operating frequency. This process is repeated until the frequency channels to be examined have been measured.

[0084] Once the frequency channels to be examined for one connection have been measured, the same measurement is carried out for another connection between the primary network node and another secondary network node, and so on.

[0085] In an optional step S04, if the BMS has at least one further master BMS unit or at least one auxiliary master BMS unit, step a1) can additionally be carried out for the at least one further master BMS unit or the at least one auxiliary master BMS unit, and in a step a2), the slave BMS units are each assigned to one of the at least two master BMS units or the master BMS units or the at least one auxiliary master BMS unit depending on the determined connection quality parameter values ​​in order to form sub-networks, and steps S05 and S07 described below are each carried out for the sub-networks, wherein the at least one auxiliary master BMS unit comprises a slave BMS unit which is additionally designed to perform one or more functions of a master BMS unit.

[0086] In a step S05, the frequency channels are classified, in particular assigned to a white list (first group) or a black list (second group).

[0087] The respective frequency channel is assigned to a first group and thus classified as "sufficiently strong" if the connection quality parameter values ​​determined for the respective frequency channel meet a specified condition. If the connection quality parameter values ​​determined for the respective frequency channel do not meet the specified condition, the frequency channel is assigned to the second group and thus classified as "too weak."

[0088] In a step S07, an instruction is provided to the master BMS unit, which includes the usable frequency channels of the first group and which causes the master BMS unit, during operation, to determine a frequency channel from the first group for a respective connection event (transmission of one of the main frames) depending on a predetermined rule or a predetermined algorithm, and the primary network nodes and the secondary network nodes to send the respective main frame with the data in the determined frequency channel.

[0089] Steps S03, S04, S05, and S07 can be performed, for example, during a calibration phase for the battery management system. In this case, all connections between the primary network node and the respective secondary network nodes and all K frequency bands are preferably analyzed.

[0090] Alternatively or additionally, in particular step S03 and step S05 can be carried out again at predetermined time intervals during an active operation of the BMS, in which the BMS controls and / or monitors charging or discharging of the battery.

[0091] The program will therefore continue, for example, during active BMS operation, where the BMS controls and / or monitors the charging or discharging of the battery. During active BMS operation, additional connection quality parameters can be determined, for example, by the master BMS unit and provided to the program.

[0092] During active operation, alternative or additional connection quality parameters can thus be used to optimize the classification of the frequency channels. Depending on the additional connection quality parameter values, steps S03, S05, and S07 are repeated for the network or for the subnetworks. Additional connection quality parameters used include, for example, data throughput and / or error rate and / or repetition rate and / or an indicator of the received field strength determined in a cycle.

[0093] In particular, the connection quality parameters of the respective connections (between the primary network node and the respective secondary network nodes) can be checked at predetermined time intervals for a respective frequency channel of the first group, and if the values ​​of the connection quality parameters of the respective frequency channel are too low (e.g. for data throughput or indicator for the reception field strength) or too high (e.g. for error rate or repetition rate), the respective frequency channel is assigned to the second group.

[0094] Alternatively or additionally, at predetermined time intervals and / or when a minimum number of frequency channels in the first group is not reached, steps S03, S05 and S07 can be carried out for frequency channels of the second group in order to increase the number of usable frequency channels again after, for example, a temporary disturbance no longer occurs.

[0095] For example, the program is terminated when the BMS operation is stopped.

[0096] Fig. Figure 4 shows four exemplary frequency responses H1(f), H2(f), H3(f), and H4(f) of slave BMS units at selected installation positions relative to the master BMS unit. It can be seen that narrowband dips occur in each case, but also that broadband attenuations occur in some cases. The frequency channels where the dips occur can be easily detected and assigned to the second group of frequency channels (blacklist).

[0097] To improve data transmission, a frequency hopping technique is used, whereby specific, particularly "weak" frequency channels are removed from the frequency hopping sequence. This explicit masking of "weak" channels compensates for installation-related disadvantages and reduces the influence of narrowband stationary interference.

[0098] Preferably, the primary network node and the secondary network nodes are configured to additionally transmit the data using frequency spread. List of reference symbols 1 battery 5 Battery unit 10 Master BMS unit 20 battery module 30 Slave BMS unit 40 central processing unit 50 mounting frames 60 housing cover 70 Case back 1_DL, 2_DL downlink frames 1_UP i , 2_UP i Uplink frame SF1, SF2 main frame S01...S11 program steps

Claims

[1] Method for operating a wireless network of a battery management system, BMSs, for a battery (1), in particular a traction battery of a vehicle, wherein - the BMS comprises a master BMS unit (5) having a master control unit and a primary network node coupled to the master control unit, and a plurality of slave BMS units (30), each having a slave control unit and a secondary network node coupled to the slave control unit, - the primary network node and the respective secondary network node are configured to communicate with each other using a predetermined wireless communication protocol, wherein the communication protocol uses a time-based main frame (SF1, SF2) to transmit data and a number of K frequency channels are available for data transmission, and the method comprises the following steps: a1) determining a matrix of connection quality parameter values ​​depending on provided measured values, wherein the matrix has a connection quality parameter value for at least some of the wireless communication connections between the primary network node and a respective secondary network node for at least some of the frequency channels, and the provided measured values ​​are each representative of a signal quality for a signal received by the primary network node in a respective frequency channel from a respective secondary network node, b) classifying the frequency channels, whereby the respective frequency channel is assigned to a first group if the connection quality parameter values ​​determined for the frequency channel satisfy a predetermined condition, and the respective frequency channel is assigned to a second group if the connection quality parameter values ​​determined for the frequency channel do not satisfy the predetermined condition, c) providing an instruction for the master BMS unit (5) which comprises the usable frequency channels of the first group and which causes the master BMS unit (5) to determine, during operation for a respective connection event, a frequency channel from the first group depending on a predetermined rule or a predetermined algorithm and the primary network nodes and the secondary network nodes to send the respective main frame (SF1, SF2) with the data in the determined frequency channel. [2] Method according to claim 1, wherein the BMS has at least one further master BMS unit (5) or at least one auxiliary master BMS unit and step a1) is additionally carried out for the at least one further master BMS unit or the at least one auxiliary master BMS unit and in a step a2) the slave BMS units (30) are each assigned to one of the at least two master BMS units (5) or either the master BMS unit (5) or the at least one auxiliary master BMS unit depending on the determined connection quality parameter values ​​in order to form sub-networks and steps b) and c) are each carried out for the sub-networks, wherein the at least one auxiliary master BMS unit comprises a slave BMS unit (30) which is additionally designed to carry out one or more functions of a master BMS unit (5). [3] Method according to one of the preceding claims, in which at least steps a1) and b) are carried out in a calibration phase for the battery management system. [4] Method according to one of the preceding claims, wherein the connection quality parameter comprises an indicator of a reception field strength. [5] Method according to one of the preceding claims, in which during an active operation of the BMS, in which the BMS controls and / or monitors charging or discharging of the battery, further connection quality parameter values ​​are provided or received, and depending on the further connection quality parameter values, steps a1) and b) or steps a1), a2) and b) are carried out again. [6] The method of claim 5, wherein the connection quality parameter values ​​comprise values ​​of at least one connection quality parameter from the following set: data throughput, error rate, repetition rate and an indicator of the received field strength determined in a cycle. [7] Method according to one of the preceding claims, in which, after a predetermined period of time or when the first group falls below a minimum number of frequency channels, steps a1), b) and c) are carried out again for at least some of the respective wireless communication connections between the primary network node and a respective secondary network node for at least some of the frequency channels of the second group. [8] Control unit for operating a wireless network of a battery management system, BMSs, for a battery (1), in particular a traction battery of a vehicle, the BMS comprising the following: - a master BMS unit (5) with a master control unit and a primary network node coupled to the master control unit, and - a plurality of slave BMS units (30), each comprising a slave control unit and a secondary network node coupled to the slave control unit, wherein the primary and the respective secondary network nodes are configured to communicate with each other using a predetermined wireless communication protocol, wherein the communication protocol uses a time-based main frame (SF1, SF2) for transmitting data and a number of K frequency channels are available for data transmission, and wherein the control unit comprises at least one processor and at least one program memory and is configured to carry out the method according to one of claims 1 to 7. [9] Having a battery control system - a control unit according to claim 8 and - a battery management system, BMS, for a battery (1), in particular a traction battery of a vehicle, the BMS comprising the following: -- a master BMS unit (5) comprising a master control unit and a primary network node coupled to the master control unit, and -- a plurality of slave BMS units (30), each comprising a slave control unit and a secondary network node coupled to the slave control unit, wherein the primary and the respective secondary network nodes are configured to communicate with each other using a predetermined wireless communication protocol, wherein the communication protocol uses a time-based main frame (SF1, SF2) to transmit data and a number of K frequency channels are available for data transmission. [10] A battery system comprising a plurality of battery modules (20), each comprising one or more battery cells, and a battery control system according to claim 9. [11] Computer program comprising instructions which, when the program is executed by a control computer, cause the control computer to carry out the method according to one of claims 1 to 7. [12] A computer-readable medium comprising instructions which, when executed by a control computer, cause the control computer to carry out the method according to any one of claims 1 to 7.

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