Automotive battery cell monitoring system with independent power supply and point-to-point Ethernet communication
The cell monitoring system with Ethernet connections and alternative power supplies addresses power failure and interoperability issues, ensuring continuous cell monitoring and efficient identification of faulty cells, reducing complexity and power consumption.
Patent Information
- Application Number
- FR2024003585
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2024-04-08
- Publication Date
- 2026-02-20
- Estimated Expiration
- 2044-04-08
AI Technical Summary
Existing battery management systems face issues such as power failure leading to inoperability of all monitored cells, difficulty in identifying faulty cells, increased complexity with backup controllers, non-standardized communication hindering interoperability, and high power consumption contributing to battery discharge.
A cell monitoring system utilizing a zone controller and supervisory cards with Ethernet connections and alternative power supplies, featuring isolation means and high-pass filters to separate data and power frequencies, enabling robust communication and power distribution even in the event of failures, and using point-to-point Ethernet connections for efficient cell supervision.
Ensures continuous monitoring and identification of faulty cells without replacing all cells, reduces complexity, enhances interoperability, and minimizes power consumption, thus improving the efficiency and cost-effectiveness of battery management.
Smart Images
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Abstract
Description
Title of the invention: Automotive battery cell monitoring system with independent power supply and point-to-point Ethernet communication technical field
[0001] The invention has as its technical field battery management, and more particularly battery management based on cell sensor circuits. Previous techniques
[0002] A battery generally comprises a certain number of battery cells, for example 24 battery cells.
[0003] In order to monitor such batteries, a CMS (Cell Management System) is used. The CMS cell management system includes at least one CSC (Cell Sensor Circuit) responsible for monitoring at least one cell 11 of battery 10. Figure [Fig. 1] illustrates such a system.
[0004] Cell monitoring refers to determining the voltage across each cell. Several CSC cell sensor circuits are required to monitor all the cells in a battery.
[0005] These CSC cell sensor circuits are connected in a daisy chain, that is, via isolated point-to-point communication buses (isolation by capacitive coupling or transformers). One of the CSC cell sensor circuits interfaces with an external microcontroller that provides communication with the rest of the vehicle. The CSC cell sensor circuit connected to the external microcontroller acts as the master controller, since the data from the other CSC cell sensor circuits passes through it before reaching the external microcontroller.
[0006] Each CSC cell sensor circuit is powered directly by the monitored battery cells. Since the cells in a battery are connected in series, the failure of one cell causes all the cells to fail. If one of the cells monitored by the CSC cell sensor circuit fails, the corresponding CSC cell sensor circuit is no longer powered. It is then impossible to determine which battery cell has failed.
[0007] Furthermore, the unpowered CSC cell sensor circuit can no longer act as a relay for information determined by the other CSC cell sensor circuits located downstream of the connection to the master controller. Access to all CSC cell sensor circuits from the unpowered cell sensor circuit is thus lost. failing.
[0008] It should be noted that in some cases, a backup master controller, located last in the chain of CSC cell sensor circuits relative to the master controller, is provided. This allows the direction of the chain connection to be reversed, restoring access to the CSC cell sensor circuits that were previously inaccessible via the master controller. Even in this case, the CSC cell sensor circuit normally powered by the group of cells containing the faulty cell remains inaccessible. Furthermore, the presence of such a backup master controller increases the cost of a battery management system.
[0009] Such a battery management system obviously presents a number of problems.
[0010] A first problem is related to the failure of the power supply of a CSC cell sensor circuit which renders inoperative the monitoring of all the monitored cells.
[0011] A second problem is related to the difficulty of determining which battery cell is faulty in the event of a power failure to a CSC cell sensor circuit. Since voltage and current measurements of the individual cells are no longer available, it is not possible to determine which faulty cell(s) need replacing. It is then necessary to replace all the cells or test them individually. In both cases, the repair is not economically efficient.
[0012] A third problem is related to the increased complexity of a battery management system equipped with a backup controller allowing the direction of interrogation of the CSC cell sensor circuit chain to be reversed.
[0013] A fourth problem is related to the non-negligible consumption of the CSC cell sensor circuits contributing to the discharge of the battery.
[0014] A fifth problem is related to the fact that so-called "daisy chain" type communication is not standardized and becomes a hindrance to the interoperability of solutions.
[0015] The present invention aims to address these various technical problems. Description of the invention
[0016] The invention relates to a cell monitoring system for a traction battery of an automobile, comprising a zone controller and at least two monitoring cards, each monitoring card being designed to monitor at least one cell of the traction battery through voltage measurements, in which:
[0017] a. The zone controller is connected to two supervisory cards via a first Ethernet connection and a second Ethernet connection, the supervisory cards being connected to each other in pairs via a third Ethernet connection,
[0018] b. The zone controller comprises a microcontroller, a first Ethernet interface, a second Ethernet interface, and an alternative power supply, the microcontroller being designed to control the Ethernet interfaces and the alternative power supply,
[0019] c. the alternative power supply being designed so as to power the Ethernet interfaces and the microcontroller of the zone controller,
[0020] d. the alternative power supply also being designed to provide power over a twisted pair of conductors via the first Ethernet connection between the zone controller and a supervisory card,
[0021] e. Each supervisory card comprises a data processing stage and a power supply stage, the data processing stage comprising a first Ethernet interface connected to one of the Ethernet connections via a first isolation means and a first high-pass filter and a second Ethernet interface connected to another of the Ethernet connections via a second isolation means and a second high-pass filter, the high-pass filters being designed so as to allow only data-related voltage variations to pass through the Ethernet interface while rejecting supply voltage variations, the data processing stage also comprising at least two cell supervisors, each designed to monitor at least one battery cell,The power supply stage is connected via an Ethernet connection to provide power to each cell supervisor and to the Ethernet interfaces of the supervisory board.
[0022] f. each supervisory card comprising a secondary alternative power supply designed to provide power over a twisted pair of conductors via an Ethernet connection between two supervisory cards,
[0023] g. the alternative power supplies being designed so that their supply frequency is chosen to be significantly lower than the data frequency and so as to be able to be filtered by the high-pass filters.
[0024] The power supply stage may include, for each cell supervisor, an isolation means connected on one side to an AC-DC converter and on the other side to the Ethernet connection via a power supply connection.
[0025] The isolation means may be of the inductive type, in particular an isolation transformer.
[0026] An isolation means may be disposed between the Ethernet interfaces and the Ethernet connections as well as between the high-pass filters and the Ethernet connections.
[0027] An isolation means may be disposed between the first Ethernet connection and the alternative power supply of each zone controller, an isolation means being disposed between the third Ethernet connection and the auxiliary alternative power supply of each monitoring card.
[0028] An isolation means may be of the inductive type, in particular an isolation transformer.
[0029] The data processing stage may include a data buffer connected between the Ethernet interfaces and the cell supervisors.
[0030] In a supervisory card, the cell supervisors can form a chain in which the first cell supervisor is connected by a first point-to-point connection to the data buffer and by another point-to-point connection to another cell supervisor, the other cell supervisors being connected each to their nearest neighbor by a second point-to-point connection, so that the data emitted by a cell supervisor passes from one to the next until it reaches the data buffer.
[0031] The first point-to-point connection can be an SPI connection, the second point-to-point connection being a galvanically isolated SPI connection.
[0032] In a supervisory card, the cell supervisors can each be connected to the data buffer via a data bus.
[0033] The data bus may be of the SPI type, with at least one of the cell supervisors being isolated from the data bus by means of an isolation capacitor. Brief description of the drawings
[0034] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:
[0035] - Figure [Fig. 1] illustrates a system for monitoring CMS cells according to the state of earlier art,
[0036] - Figure [Fig.2] illustrates the main elements of a supervisory system cells according to the invention,
[0037] - Figure [Fig.3] illustrates the main elements of a power supply stage of a monitoring card included in a cell monitoring system according to the invention,
[0038] - Figure [Fig.4] illustrates the main elements of a processing stage data from a monitoring card included in a first embodiment of a cell monitoring system according to the invention, and
[0039] - Figure [Fig. 5] illustrates the main elements of a processing stage data from a supervisory card according to a second embodiment of a cell supervision system according to the invention. Detailed description
[0040] The SMT cell supervision system according to the invention is referenced 1 on the figure [Fig.2]. It includes a zone controller connected to at least two supervisory cards 1b by two Ethernet connections referenced 2 and 3. The Ethernet connections are in particular connections according to the IEEE 802.3cg standard, for support of the 10BASE-T1S communication protocol, using a twisted pair of conductors.
[0041] The zone controller is generally located centrally in the vehicle, or at the very least, close to the other electronic control units or computers of the vehicle. Indeed, the zone controller communicates with the other electronic control units or computers of the vehicle via an Ethernet connection.
[0042] In contrast, the supervision cards 1b are arranged on the battery 10, as close as possible to the monitored cells 11, for reasons of cost and reach of the connections to the terminals of the cells.
[0043] The zone controller la includes a microcontroller lal, a first Ethernet interface la2, a second Ethernet interface la4 and an alternative power supply la3. By Ethernet interface, we consider that it is a layer 1 hardware interface in the OSI model (English acronym for "Open System Interconnection").
[0044] Within the zone controller la, the microcontroller lal is connected by a data connection to the first Ethernet interface la2 and to the second Ethernet interface la4, in particular a connection of type xMII (English acronym for "Media Independent Interface") or SPI (English acronym for "Serial Peripheral Interface").
[0045] The first Ethernet interface la2 is connected to a first Ethernet connection 2 by a data connection 2a2 and an isolation means 2a21.
[0046] The second Ethernet interface la4 is connected to a second Ethernet connection 3 by a data connection 2a4 and an isolation means 2a41.
[0047] The alternative power supply la3 supplies the first Ethernet interface la2, the second Ethernet interface la4 and the microcontroller lal via an AC-DC converter not shown.
[0048] The alternative power supply la3 is also connected to the first Ethernet connection 2 via a power connection 2a3 and an isolation means 2a31 in order to achieve a power supply similar to the PoDL standard (English acronym for "Power Over Data Lines", IEEE 802.3bu standard) via the Ethernet connection 2.
[0049] The isolation means 2a21, 2a41 and 2a31 are in particular of the inductive type, for example isolation transformers.
[0050] In order to distinguish voltage variations related to data transmission from voltage variations related to the power supply, the frequency of the AC power supply is chosen so as to be significantly lower than the frequency related to the transmission of data, and so that it can be filtered by frequency filtering (e.g., data at a frequency of 12MHz, power supply at a frequency below 1kHz).
[0051] Each supervisory card 1b includes a data connection 2b2 and a power connection 2b3 to the Ethernet connection, each presented as a pair of conductors.
[0052] The proposed power supply is a power supply on a pair of twisted connectors, superimposed on the voltage variations generated by the data transmission.
[0053] Each supervisory card 1b includes a data processing stage and a power supply stage lb3.
[0054] The data processing stage comprises a first Ethernet interface lb20 connected to the first Ethernet connection 2 via an isolation means 2b21 and a high-pass filter 1b19, and a second Ethernet interface lb40 connected to a third Ethernet connection 4 via an isolation means 2b41 and a high-pass filter lb39. The high-pass filters lbl9 and lb39 are designed to separate voltage variations related to data transmission from voltage variations related to the AC power supply.
[0055] The Ethernet interfaces lb20 and lb40 are both connected to the same data buffer lb21, which is itself connected to at least one cell supervisor lb22 via an SPI serial communication connection. In a particular embodiment, the data buffer lb21 is connected to the Ethernet interfaces lb20 and lb40 via an xMII connection. The role of the data buffer lb21 is to manage the conversion of the data exchanged between the at least one cell supervisor lb22 and the Ethernet interfaces lb20 and lb40, as well as to manage any potential asynchronicity.
[0056] Each lb22 cell supervisor performs the supervision of a plurality of 11 battery cells. Each data processing stage can include up to eight lb22 cell supervisors.
[0057] The power supply stage lb3 includes a power connection to each cell supervisor lb22 equipped with an isolation means lb31 and an AC-DC converter lb32. Figure [Fig.3] illustrates the power supply stage lb3 of a supervisory card.
[0058] Although costly, supplying an lb32 AC-DC converter for each lb22 cell supervisor is particularly advantageous by allowing the necessary supply power to be provided taking into account a different reference voltage for each lb32 AC-DC converter and indexed to the voltage of the monitored cells.
[0059] Each supervisory card is equipped with a secondary power supply lb33 connected by an isolation means to the third Ethernet connection 4 via a isolation means 2b34, in order to achieve a power supply in a manner similar to the alternative power supply la3 of the zone controller.
[0060] The supervisory cards 1b are connected in pairs by a third Ethernet connection 4, allowing data to be exchanged bidirectionally and power to be supplied to one supervisory card by an immediately adjacent supervisory card.
[0061] The last supervisory card is connected via a first high-pass filter and a first Ethernet interface to a third Ethernet connection and via a second high-pass filter and a second Ethernet interface to the second Ethernet connection 3. It is recalled that the second Ethernet connection 3 is connected to the second Ethernet interface la4 of the zone controller la.
[0062] In the event of a failure of a supervisory card upstream of the last supervisory card, such a connection via the second Ethernet connection 3 makes it possible to route the information of all the supervisory cards between the failed card and the last supervisory card so as not to lose access to the cells monitored by these cards.
[0063] It should be noted that no mention is made of the presence of a secondary power supply in the last supervisory card. Such a secondary power supply is not necessary because the second Ethernet connection 3 does not require a power supply. Indeed, the second Ethernet connection 3 is only connected to the zone controller 1a, which includes its own power supply.
[0064] However, in the interest of standardizing components, the last supervisory card may include a secondary power supply, which then remains unconnected to the second Ethernet connection 3.
[0065] In a first embodiment of a data processing stage, illustrated in Figure 4, a first cell supervisor is connected to the data buffer lb21 via a first SPI serial communication connection. The first cell supervisor is then connected to a second cell supervisor via a second ISO SPI serial communication connection. An ISO SPI connection is understood to be an SPI serial connection including galvanic isolation. Each of the other cell supervisors is connected to only one other cell supervisor via an ISO SPI serial communication connection, so as to form a daisy chain.
[0066] Such an embodiment is close to the state of the art, while simplifying data connections due to the use of SPI and ISO SPI serial communication connections and solving the problems of powering the lb22 cell supervisors by powering them from the data connection instead of powering them from the battery cells.
[0067] In a second embodiment of a data processing stage, illustrated in Figure [Fig. 5], an SPI data bus connects each of the cell supervisors lb22 with the data buffer lb21. Preferably, each of the cell supervisors lb22 is provided with galvanic isolation lb23 at its connection to the SPI data bus. The galvanic isolation of the first cell supervisor can be omitted because it is powered by the same supply as the data buffer lb21 and the Ethernet interface lb20. Any fault affecting the Ethernet interface and the data buffer would also affect its ability to communicate.
[0068] Galvanic isolation lb23 of cell supervisors is achieved via a digital circuit, in particular of optical, capacitive, radio frequency or inductive type.
[0069] This embodiment offers the advantage of improved robustness of the supervisory board by making communication between the data buffer and the cell supervisors independent of the operation of each individual cell supervisor. In the event of a failure of one of the cell supervisors, the other cell supervisors remain accessible.
Claims
Demands
1. A cell monitoring system (11) for a motor vehicle traction battery, comprising an area controller (1a) and at least two monitoring cards (1b), each monitoring card (1b) being designed to monitor at least one cell (11) of the traction battery by means of voltage measurements, characterized in that: a. The zone controller (la) is connected to two supervisory cards (1b) via a first Ethernet connection (2) and a second Ethernet connection (3), the supervisory cards (1b) being connected to each other in pairs via a third Ethernet connection (4), b. The zone controller (la) comprises a microcontroller (lal), a first Ethernet interface (la2), a second Ethernet interface (la4) and an alternative power supply (la3), the microcontroller (lal) being designed to control the Ethernet interfaces (Ia2,la4) and the alternative power supply (la3), c. the alternative power supply (la3) being designed so as to power the Ethernet interfaces (Ia2,la4) and the microcontroller (lal) of the zone controller (la), d. the alternative power supply (la3) also being designed so as to provide power over a twisted pair of conductors via the first Ethernet connection (2) between the zone controller (la) and a supervisory card (1b), e. Each supervisory card (1b) comprises a data processing stage and a power supply stage, the data processing stage comprising a first Ethernet interface (lb20) connected to one of the Ethernet connections via a first isolation device (2b21) and a first high-pass filter (1b19) and a second Ethernet interface (lb40) connected to another of the Ethernet connections via a second isolation device (2b41) and a second high-pass filter (lb39), the high-pass filters (1b19, lb39) being designed so as to allow only voltage variations to pass through the Ethernet interface (lb20, lb40) related to the data by rejecting supply voltage variations, the data processing stage also comprising at least two cell supervisors (lb22) each designed to monitor at least one cell (11) of the battery, the power stage being connected to an Ethernet connection (2,3) so as to provide power to each cell supervisor (lb22) and to the Ethernet interfaces (lb20, lb40) of the supervisor card (1b), f. each supervisor card comprising a secondary alternative power supply (lb33) designed to provide power over a twisted pair of conductors via an Ethernet connection between two supervisor cards (1b), g.the alternative power supplies (Ia3,lb33) being designed so that their supply frequency is chosen to be significantly lower than the frequency linked to the data and so that it can be filtered by the high-pass filters.
2. Supervisory system according to claim 1, wherein the power supply stage comprises, for each cell supervisor (lb22), an isolation means (lb31) connected on one side to an AC-AC-DC converter (lb32) and on the other side to the Ethernet connection (2) via a power supply connection.
3. Supervisory system according to claim 2, wherein the isolation means (lb31) is of the inductive type, in particular an isolation transformer.
4. Supervisory system according to any one of claims 1 to 3, wherein an isolation means (2a21,2b21,2b41) is disposed between the Ethernet interfaces (Ia2,la4) and the Ethernet connections (2,3) as well as between the high-pass filters (Ibl9,lb39) and the Ethernet connections (2,3,4).
5. Supervisory system according to claim 4, wherein an isolation means (2a31) is disposed between the first Ethernet connection (2) and the alternative power supply (1a3) of each zone controller (la), an isolation means (2b34) being disposed between the third Ethernet connection (4) and the auxiliary alternative power supply (lb33) of each supervisor card.
6. Supervisory system according to claim 4 or 5, wherein an isolation means (2a21,2a41,2a31,2b21,2b41,2b34) is of the inductive type, in particular an isolation transformer.
7. Supervisory system according to any one of claims 1 to 6, wherein the data processing stage includes a data buffer (lb21) connected between the Ethernet interfaces (lb20, lb40) and the cell supervisors (lb22).
8. Supervisory system according to claim 7, wherein, in a supervisory card (1b), the cell supervisors (lb22) form a chain in which the first cell supervisor (lb22) is connected by a first point-to-point connection to the data buffer (lb21) and by another point-to-point connection to another cell supervisor (lb22), the other cell supervisors (lb22) being connected each to their nearest neighbor by a second point-to-point connection, so that the data emitted by a cell supervisor (lb22) passes from one to the next until it reaches the data buffer (lb21).
9. Supervisory system according to claim 8, wherein the first point-to-point connection is an SPI connection, the second point-to-point connection being a galvanically isolated SPI connection.
10. Supervisory system according to any one of claims 7 to 9, wherein, in a supervisory card (1b), the cell supervisors (lb22) are each connected to the data buffer (lb21) via a data bus.
11. Supervisory system according to claim 10, wherein the data bus is of type SPI, at least one of the cell supervisors (lb22) being isolated from the data bus via an isolation capacitor (lb23).