Battery unit and communication method in one battery unit

Abstract

Battery unit (100) comprising at least two battery modules (1-3) and a central control unit (4) which are interconnected by data technology, wherein the data communication between the battery modules (1-3) and the central control unit (4) is designed as optical data communication, wherein each battery module (1-3) and the central control unit (4) have at least one optical transmitter (S1-S4, S1'-S4') and at least one optical receiver (E1-E4, E1'-E4'), characterized in that the optical transmitters (S1-S4, S1'-S4') are designed such that their optical transmission power (P) is adjusted depending on at least one parameter, wherein the at least one parameter is a determined optical transmission power (P) of the transmitter, which is determined directly at the transmitting battery module (1-3).

Description

[0001] The invention relates to a battery unit and a communication method in such a battery unit.

[0002] Such a battery unit typically comprises a housing in which several battery modules are arranged. The battery modules themselves contain a multitude of battery cells connected in series and / or parallel. The external contacts of the connected battery modules then form the battery terminals. It is also known to assign measuring and control units to the battery modules, which measure the cell voltages and, if necessary, the temperature of the battery cells, as well as perform cell balancing. These measuring and control units are connected to a central control unit of the battery unit, to which the measurement data is transmitted and from which control commands for cell balancing are received. The data connection is established, for example, via a CAN, SPI, IsoSPI, or I2C bus.

[0003] Due to the high currents in such battery units, interference can occur in electrical data communication.

[0004] From DE 10 2017 204 138 A1, a battery unit is known comprising at least two battery modules and at least two measuring and control units, which are connected to at least one central control unit via data communication. The data communication is implemented as optical free-space communication, wherein the measuring and control units each have at least one optical transmitter and the central control unit has at least one optical receiver, and the optical free-space communication between the measuring and control units and the central control unit takes place directly, excluding the other measuring and control units.

[0005] The advantage of direct optical free-space communication is its robustness against electromagnetic interference and the elimination of complex cabling. Compared to free-space communication in the form of daisy-chain communication or similar approaches based on communication between measurement and control units, it is significantly faster, especially as the number of battery modules increases. Data handling is also simpler.

[0006] However, reliable technical implementation is not easy.

[0007] From DE 10 2009 058 879 A1, an electrical energy storage system for a vehicle equipped with an electric drive is known, comprising a plurality of electrical components and data transmission devices for transmitting data signals to and / or from at least one of the components, wherein the data transmission devices include at least one transmission path for electromagnetic radiation for data signal transmission. Preferably, at least one transmission path is designed as an optical fiber for optical data signal transmission.

[0008] A battery unit of this type is known from DE 10 2012 202 690 A1.

[0009] From EP 1 641 148 A1, a method for optimizing the light power in an optical network is known, wherein the optical light power is detected at a receiver and this result is then transmitted back to a transmitter. The received optical power is transmitted back to the transmitter in a unidirectional ring structure. This ring structure can also be bidirectional.

[0010] A similar procedure is disclosed in DE 103 28 684 A1 or WO 2015 / 094 405 A2.

[0011] The invention is based on the technical problem of creating a battery unit in which communication is improved, as well as providing a communication method.

[0012] The solution to the technical problem is achieved by a battery unit having the features of claims 1 and 3 and a communication method having the features of claims 8 and 9. Further advantageous embodiments of the invention are set forth in the dependent claims.

[0013] The battery unit comprises at least two battery modules and a central control unit, which are interconnected via data transmission. Data communication between the battery modules and the central control unit is implemented optically. Each battery module and the central control unit has at least one optical transmitter and at least one optical receiver. The transmitters are designed such that their optical transmission power is adjusted depending on at least one parameter. This allows for the lowest possible electrical energy consumption for operating the communication while still ensuring reliable operation. The adjustable transmission power enables the unit to respond to changes in the transmission power. In addition to reducing the voltage, this also results in a longer lifespan for both the transmitter and receiver. The transmitter can be, for example, a laser diode or an LED.The receiver is designed, for example, as a photodiode or a photoresistor. The optical transmission power is adjusted by modifying the electrical parameters (preferably the current) of the optical transmitter.

[0014] At least one parameter is the transmission power itself, which is measured directly at the transmitting battery module. To illustrate, a portion of the transmission power is diverted and evaluated. This allows the transmitter to know how much transmission power it is actually emitting (visually).

[0015] In one embodiment, the battery modules and the central control unit are connected via a unidirectional or bidirectional ring structure (also known as a daisy chain). This provides a very robust data connection, with the bidirectional ring structure being faster, especially with many participants, but requiring slightly more complex circuitry.

[0016] Alternatively, at least one parameter is the received power at a receiver of a neighboring communication participant (battery module or central control unit). In simpler terms, the receiver indicates whether the received power is sufficient so that the transmitter can adjust its transmit power. If the received power is too low, for example, the transmit power is increased, and vice versa. The battery modules and the central control unit are connected in a bidirectional ring structure. Each battery module and the central control unit has at least two transmitters and two receivers, with the battery unit designed such that received power is immediately transmitted back from the receiver to the transmitting participant. This allows for very rapid adaptation of the transmitter's transmit power.

[0017] In one embodiment, the transmitting device is configured to automatically increase its transmit power if it does not receive any signal from the receiving device. This ensures that communication is not interrupted due to insufficient transmit power.

[0018] In another embodiment, at least one parameter is temperature. This counteracts the effect of lower optical power of the transmitter at low temperatures. Alternatively or additionally, the parameter can also be the transmitter's lifetime. This compensates for transmitter aging. Alternatively or additionally, the parameter can also be the transmitter's operating time and / or number of operating cycles.

[0019] In another embodiment, the battery modules and / or the control unit are designed to store the set transmission power. This ensures that the adaptation learned during operation is not lost. The storage can take place locally and / or centrally.

[0020] In another embodiment, the optical data transmission is at least partially fiber-guided. This allows for reliable data transmission even with complex spatial arrangements of the battery modules.

[0021] Furthermore, it may be provided that when a transmitter reaches its maximum transmission power or when a threshold value is reached just before the maximum transmission power, a warning or diagnostic signal is generated to indicate that the transmitter will soon need to be replaced.

[0022] Regarding the procedural design of the invention, reference is made to the preceding statements.

[0023] A preferred application for the battery unit is its use as a traction battery in an electric or hybrid vehicle.

[0024] The invention is explained in more detail below with reference to preferred embodiments. The figures show: Fig. 1 a schematic block diagram of a battery unit in a first embodiment, Fig. 2 a schematic partial representation of a battery unit in a second embodiment, Fig. 3 a schematic partial representation of a battery unit in a third embodiment and Fig. 4 a representation of the electrical power of a transmitter over time of a fourth embodiment.

[0025] In the Fig. Figure 1 schematically depicts a battery unit 100 in a first embodiment. The battery unit 100 comprises, for example, three battery modules 1-3 and a central control unit 4 (also referred to as a BMC battery management controller). The battery modules 1-3 each comprise a plurality of battery cells, which are not shown. The battery cells 1-3 are electrically interconnected, which is also not shown for clarity. The battery modules 1-3 have sensors to detect measured variables within the battery modules 1-3, such as voltage, current, and / or temperature of the battery cells. Furthermore, the battery modules 1-3 have control units (also referred to as CMC cell module controllers) that can control the battery cells, for example, for cell balancing, and transmit the measured variables to the central control unit 4.The control units of battery modules 1-3, which are not shown, also control this data communication, i.e. the transmission of the measured values ​​as well as the receipt and implementation of control commands from the central control unit 4.

[0026] Battery modules 1-3, together with the central control unit 4, form a bidirectional ring structure for data communication. For this purpose, battery modules 1-3 and the central control unit 4 each have two optical transmitters S1-S4, S1'-S4' and two optical receivers E1-E4, E1'-E4'. One communication direction runs, for example, from S1 to E2', S2 to E3', S3 to E4', and from S4 to E1'. The other communication path then runs via S1', E4, S4', E3, S3', E2, S2' to E1.

[0027] Optical fibers 5 are arranged between transmitter S1' and receiver E4, transmitter S4 and receiver E1', transmitter S3 and receiver E4', and transmitter S4' and receiver E3. It should be noted that all communication links can be fiber-guided or free-space communication.

[0028] The optical transmitters S1-S4, S1'-S4' are designed, for example, as laser diodes or LEDs, with their optical power being adjustable. This is achieved, for instance, by increasing the current through the LED. The optical transmission power is adjusted to achieve the lowest possible transmission power while still maintaining sufficient reception quality. This will now be illustrated using the communication between the first battery module 1 and the second battery module 2 as an example. The first battery module 1 transmits data to the second battery module 2 via optical transmitter S1. The data is received at receiver E2' and then forwarded via transmitter S2 (possibly with additional data from the second battery module 2).In the second battery module 2, the received signal at receiver E2' is evaluated and transmitted back to the first battery module 1 via transmitter S2'. Based on this information, the first battery module 1 knows whether the transmitted power from transmitter S1 is too high, too low, or just right. The transmitted power is adjusted accordingly, ensuring reliable communication with minimal electrical power consumption. This allows for the compensation of factors such as aging, contamination, etc.

[0029] In the Fig. Figure 2 shows the first battery module 1 and the second battery module 2 in an alternative embodiment where only a unidirectional ring structure is provided. Accordingly, the first battery module 1 has only one optical transmitter S1 and one optical receiver E1. The same applies to the second battery module 2. In this case, the second battery module 2 cannot directly transmit the determined received power P(E2) back to the first battery module 1, but transmits it back to the first battery module 1 via the ring. This results in a slightly slower adjustment of the transmitted power. The advantage over the embodiment according to Figure 2 is that... Fig. Advantage 1 is that fewer components are required. Preferably, the first battery module 1 starts with the maximum transmit power, which is then adjusted downwards after receiving the power P(E2).

[0030] In the Fig. Figure 3 shows another alternative embodiment. In this embodiment, a portion P' of the optical transmission power P of the optical transmitter S1 is extracted to determine the optical transmission power P. This extraction can be achieved, for example, by means of reflections or beam segments. Depending on the configuration (unidirectional or bidirectional), the received power at the second battery module 2 can also be transmitted to the first battery module 1.

[0031] Another possibility is to measure the electrical power P el to continuously increase the optical transmit power over its lifetime to compensate for aging effects of the optical transmitter and receiver, ensuring sufficient optical transmit power. This increase can be achieved as described in Fig. 4. The curve can be represented linearly or as steps. Other curve shapes are also possible. Preferably, a threshold value P exists. g (e.g. 90% of the maximum power P) max), upon reaching which a warning signal is generated. The advantage of this variant is that no measurement results are required to adapt the transmission power.

Claims

[1] Battery unit (100) comprising at least two battery modules (1-3) and a central control unit (4) which are interconnected by data technology, wherein the data communication between the battery modules (1-3) and the central control unit (4) is designed as optical data communication, wherein each battery module (1-3) and the central control unit (4) have at least one optical transmitter (S1-S4, S1'-S4') and at least one optical receiver (E1-E4, E1'-E4'), characterized by , that the optical transmitters (S1-S4, S1'-S4') are designed such that their optical transmit power (P) is adjusted depending on at least one parameter, wherein the at least one parameter is a determined optical transmit power (P) of the transmitter, which is determined directly at the transmitting battery module (1-3). [2] Battery unit according to claim 1, characterized by, that the battery modules (1-3) and the central control unit (4) are connected in a unidirectional or bidirectional ring structure. [3] Battery unit (100) comprising at least two battery modules (1-3) and a central control unit (4) which are interconnected by data technology, wherein the data communication between the battery modules (1-3) and the central control unit (4) is designed as optical data communication, wherein each battery module (1-3) and the central control unit (4) have at least one optical transmitter (S1-S4, S1'-S4') and at least one optical receiver (E1-E4, E1'-E4'), characterized by, that the optical transmitters (S1-S4, S1'-S4') are designed such that their optical transmit power (P) is adjusted depending on at least one parameter, wherein the battery modules (1-3) and the central control unit (4) are connected in a bidirectional ring structure, wherein the at least one parameter is a received power at a receiver of a neighboring communication participant, wherein the battery modules (1-3) and the central control unit (4) each have at least two transmitters (S1-S4, S1'-S4') and two receivers (E1-E4, E1'-E4'), wherein the battery unit (100) is designed such that a received received power is immediately transmitted back from the receiving participant to the transmitting participant. [4] Battery unit according to claim 3, characterized by, that the transmitting participant is trained to automatically increase the transmit power if it does not receive any received power back from the receiving participant. [5] Battery unit according to any of the preceding claims, characterized by , that at least one parameter is a temperature and / or a lifetime (t) of the transmitter (S1-S4, S1'-S4') and / or an operating time and / or a number of operating cycles of the transmitter (S1-S4, S1'-S4'). [6] Battery unit according to any of the preceding claims, characterized by , that the battery modules (1-3) and / or the central control unit (4) are designed to store the set transmission power. [7] Battery unit according to any of the preceding claims, characterized by that the optical data transmission is at least partially fiber-guided. [8] Communication method in a battery unit (100) by means of at least two battery modules (1-3) and a central control unit (4) which communicate with each other by means of optical data communication, wherein each battery module (1-3) and the central control unit (4) have at least one optical transmitter (S1-S4, S1'-S4') and one optical receiver (E1-E4, E1'-E4'), characterized by , that the optical transmit power (P) of the optical transmitters is adjusted depending on at least one parameter, wherein the at least one parameter is a determined transmit power (P) of the transmitter, which is determined directly at the transmitting battery module (1-3). [9] Communication method in a battery unit (100) by means of at least two battery modules (1-3) and a central control unit (4) which communicate with each other by means of optical data communication, wherein each battery module (1-3) and the central control unit (4) have at least one optical transmitter (S1-S4, S1'-S4') and one optical receiver (E1-E4, E1'-E4'), characterized by, that the optical transmit power (P) of the optical transmitters is adjusted depending on at least one parameter, wherein the at least one parameter is a receiving line at a receiver of an adjacent communication participant, wherein the battery modules (1-3) and the central control unit (4) are connected in a bidirectional ring structure, wherein the battery modules (1-3) and the central control unit (4) each have at least two transmitters (S1-S4, S1'-S4') and two receivers (E1-E4, E1'-E4'), wherein the battery unit (100) is configured such that a received receive power is immediately transmitted back from the receiving participant to the transmitting participant.

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