Automotive battery cell monitoring system with independent AC power supply and Ethernet communication
The cell monitoring system addresses power failure and interoperability issues by using Ethernet-connected zone controllers with alternative power and isolation, ensuring continuous monitoring and efficient cell identification while reducing complexity and power consumption.
Patent Information
- Application Number
- FR2024003584
- 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 cell sensor circuits, 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 with a zone controller connected via Ethernet, using an alternative power supply and isolation means, powers supervisory cards through a twisted pair, and employs high-pass filters and galvanic isolation to ensure data integrity and independent power supply to each cell supervisor, forming a robust communication chain.
Ensures continuous monitoring and identification of faulty cells without affecting the entire system, reduces complexity, enhances interoperability, and optimizes power usage, thereby 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 AC power supply and 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 the determination of 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 the supervisory cards via an Ethernet connection,
[0018] b. The zone controller comprises a microcontroller, an Ethernet interface and an alternative power supply, the microcontroller being designed to control the interface Ethernet and alternative power supply,
[0019] c. the alternative power supply being designed so as to power the Ethernet interface 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 Ethernet connection between the zone controller and the supervisory cards,
[0021] e. each supervisory card comprising a data processing stage and a power supply stage, the data processing stage comprising an Ethernet interface connected to the Ethernet connection via an isolation means and a high-pass filter designed so as to allow only data-related voltage variations to pass through the Ethernet interface while rejecting voltage variations related to the AC power supply, the data processing stage also comprising at least two cell supervisors each designed to monitor at least one battery cell, the power supply stage being connected to the Ethernet connection so as to provide power to each cell supervisor and to the Ethernet interface of the supervisory card.
[0022] 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.
[0023] The isolation means may be of the inductive type, in particular an isolation transformer.
[0024] An isolation means may be disposed between the Ethernet interface and the Ethernet connection as well as between the high-pass filter and the Ethernet connection.
[0025] An isolation means may be of the inductive type, in particular an isolation transformer.
[0026] An isolation means may be disposed between the Ethernet connection and the power supply stage of each supervisor card, the data processing stage isolation means and the power supply stage isolation means being coupled together, the Ethernet interface isolation means and the zone controller alternative power supply isolation means also being coupled together.
[0027] The data processing stage may include a data buffer connected between the Ethernet interface and the cell supervisors.
[0028] In a supervisory map, 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 each being connected to their nearest neighbor by a second point-to-point connection, so that the data emitted by a cell supervisor passes from one cell supervisor to the next. up to the data buffer.
[0029] The first point-to-point connection can be an SPI connection, the second point-to-point connection being a galvanically isolated SPI connection.
[0030] In a supervisory card, the cell supervisors can each be connected to the data buffer via a data bus.
[0031] The data bus may be of the SPI type, with at least one of the cell supervisors being isolated from the data bus via an isolation capability. Brief description of the drawings
[0032] 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:
[0033] - Figure [Fig. 1] illustrates a system for monitoring CMS cells according to the state of earlier art,
[0034] - Figure [Fig.2] illustrates the main elements of a supervisory system cells according to the invention,
[0035] - 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,
[0036] - 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,
[0037] - Figure [Fig. 5] illustrates the main elements of a processing stage data from a monitoring card according to a second embodiment of a cell monitoring system according to the invention, and
[0038] - Figure [Fig. 6] illustrates the main elements of a supervisory system cells according to a second embodiment of the invention. Detailed description
[0039] The SMT cell monitoring system according to the invention is referenced 1 in Figure [Fig.2]. It comprises a zone controller 1 connected to at least two monitoring cards 1b by an Ethernet connection referenced 2. The Ethernet connection is in particular a connection according to the IEEE 802.3cg standard, for support of the 10BASE-T1S communication protocol, using a twisted pair of conductors.
[0040] 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.
[0041] In contrast, the supervision cards 1b are arranged on battery 10, at most close to the monitored cells 11, for reasons of cost and range of connections to the cell terminals.
[0042] The zone controller la includes a microcontroller lal, an Ethernet interface la2 and an alternative power supply la3. By Ethernet interface, it is considered to be a layer 1 hardware interface in the OSI model (English acronym for "Open System Interconnection").
[0043] Within the zone controller la, the microcontroller lal is connected by a data connection to the Ethernet interface la2, in particular an xMII type connection (English acronym for "Media Independent Interface") or SPI type connection (English acronym for "Serial Peripheral Interface").
[0044] The Ethernet interface la2 is connected to the Ethernet connection by a data connection 2a2 and an isolation means 2a21.
[0045] The alternative power supply la3 supplies the Ethernet interface la2 and the microcontroller la3 via an AC-DC converter not shown. The alternative power supply la3 is also connected to the 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.
[0046] The isolation means 2a21 and 2a31 are in particular of the inductive type, for example an isolation transformer.
[0047] 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 la3 is chosen so as to be significantly lower than the frequency related to data transmission, and so that the voltage variations related to the power supply can be filtered by frequency filtering (for example, data at a frequency of 12MHz, power supply at a frequency lower than 1kHz).
[0048] 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.
[0049] The proposed power supply is a power supply on a pair of twisted connectors, superimposed on the voltage variations generated by the data transmission.
[0050] Each 1b supervisory card includes a data processing stage and a lb3 power supply stage.
[0051] The data processing stage includes an Ethernet interface lb20 connected to the Ethernet connection 2 via an isolation means 2b21 and a high-pass filter 1b19. The high-pass filter lbl9 is designed to separate voltage variations related to the data from voltage variations related to the AC power supply. la3 and a only allow the transmission of voltage variations related to the data. The isolation means 2b21 is notably of the inductive type, for example an isolation transformer.
[0052] The Ethernet interface lb20 is connected to a 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 interface lb20 via an xMII connection. The data buffer lb21 manages the conversion of data exchanged between the at least one cell supervisor lb22 and the Ethernet interface lb20, as well as handling any potential asynchronicity.
[0053] Each lb22 cell supervisor performs the supervision of a plurality of 11 battery cells.
[0054] 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 of a supervisor card.
[0055] 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.
[0056] 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.
[0057] Such an embodiment approaches 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.
[0058] 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 supervisors of Cell lb22 is equipped with galvanic isolation from 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.
[0059] Galvanic isolation lb23 of cell supervisors is achieved via a digital circuit, in particular of optical, capacitive, radio frequency or inductive type.
[0060] 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.
[0061] In a second embodiment of the SMT cell monitoring system illustrated in Figure [Fig. 6], the isolation means 2a21 and 2a31 are connected respectively to the AC power supply la3 and to the Ethernet interface la2 of the zone controller la by a first winding, as in the first embodiment. The second winding of the isolation means 2a31 and the second winding of the isolation means 2a21 are connected to the Ethernet connection 2 and coupled to each other by a link 4a.
[0062] At each power supply stage of a supervisory card 1b, an isolation means 2b31 is added at each power supply stage between the power connection 2b3 to the Ethernet connection and the isolation means lb31. The isolation means 2b31 is in particular of the inductive type, for example an isolation transformer.
[0063] The isolation means 2b21 and 2b31 are connected respectively to the high-pass filter lbl9 and the isolation means lb31 of each supervisory board 1b by their respective first windings. The second winding of the isolation means 2b21 and the second winding of the isolation means 2b31 are connected to the Ethernet connection 2. For convenience, the two windings can be grouped in the same component with a common midpoint referenced 4b.
[0064] Compared to the first embodiment of the SMT cell supervision system, grouping the isolation means within the same component allows for optimization of its size and cost.
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 the supervisory cards (1b) via an Ethernet connection (2), b. The zone controller (la) comprises a microcontroller (lal), an Ethernet interface, and an alternative power supply (la3), the microcontroller (lal) being designed to control the Ethernet interface (la2) and the alternative power supply (la3), c. The alternative power supply (la3) being designed to power the Ethernet interface (la2) 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 Ethernet connection (2) between the zone controller (la) and the supervisory cards (1b), e. Each supervisory card (1b) comprising a data processing stage and a power supply stage, the data processing stage comprising an Ethernet interface (lb20) connected to the Ethernet connection (2) via an isolation means (2b21) and a high-pass filter (1b19) designed to allow only data-related voltage variations to pass through the Ethernet interface (lb20) while rejecting voltage variations related to the AC power supply (1a3), 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 supply stage being connected to the Ethernet connection (2) so as to provide power to each cell supervisor (lb22) and to the Ethernet interface (lb20) of the card supervision (1b) from the power supplied by the alternative power supply (la3), f. the alternative power supply (la3) being designed so that the supply frequency is chosen to be significantly lower than the data frequency 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) is disposed between the Ethernet interface (la2) and the Ethernet connection (2) as well as between the high-pass filter (1b19) and the Ethernet connection (2).
5. Supervisory system according to claim 4, wherein an isolation means (2a21,2b21,2b31) is of the inductive type, in particular an isolation transformer.
6. Supervisory system according to claim 5, wherein an isolation means (2b31) is disposed between the Ethernet connection and the power supply stage of each supervisor card, the isolation means (2b21) of the data processing stage and the isolation means (2b31) of the power supply stage being coupled together, the isolation means (2a21) of the Ethernet interface and the isolation means (2a31) of the alternative power supply of the zone controller also being coupled together.
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 interface (lb20) and the cell supervisors (lb22).
8. A 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).