Automotive battery cell monitoring system with independent power supply and Ethernet communication
The Ethernet-connected cell monitoring system with continuous power and isolation addresses power failures and communication issues, enabling efficient identification of faulty cells and reducing complexity and consumption, thus improving battery management efficiency and interoperability.
Patent Information
- Application Number
- FR2024003583
- 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 with power failures affecting CSC cell sensor circuits, leading to inaccessible data, difficulty in identifying faulty cells, increased complexity with backup controllers, non-standardized communication, and high power consumption, which are economically inefficient and hinder interoperability.
A cell monitoring system using an Ethernet connection with a zone controller and supervisory cards, featuring a continuous power supply, isolation means, and SPI connections, allowing independent power and data transmission to each cell supervisor, reducing reliance on individual cell power and enabling robust communication.
Ensures continuous monitoring and identification of faulty cells, reduces system complexity, enhances interoperability, and minimizes power consumption, providing efficient and cost-effective battery management.
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Abstract
Description
Title of the invention: Automotive battery cell monitoring system with independent 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 the monitoring of all monitored cells inoperative.
[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 an obstacle 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 a continuous power supply, the microcontroller being designed to control the interface Ethernet and continuous power supply,
[0019] c. the continuous power supply being designed to power the Ethernet interface and the microcontroller of the zone controller,
[0020] d. the continuous 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 and to at least two cell supervisors each designed to monitor at least one cell of the battery, 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 a DC-AC converter connected at input to the Ethernet connection via a power connection, and, for each cell supervisor of the supervisory board, an isolation means connected in series to an AC-DC converter.
[0023] The isolation means may be of the inductive type, in particular an isolation transformer.
[0024] An isolation means may be disposed between each Ethernet interface and the Ethernet connection.
[0025] The means of insulation may be of a capacitive type, for example an insulation capacitor.
[0026] The data processing stage of a supervisory card may include a data buffer connected between the Ethernet interface and the cell supervisors.
[0027] 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.
[0028] The first point-to-point connection can be an SPI connection, the second point-to-point connection being a galvanically isolated SPI connection.
[0029] In a supervisory card, the cell supervisors can each be connected to the data buffer via a data bus.
[0030] 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
[0031] 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:
[0032] - Figure [Fig. 1] illustrates a system for monitoring CMS cells according to the state of earlier art,
[0033] - Figure [Fig.2] illustrates the main elements of a supervisory system cells according to the invention,
[0034] - 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,
[0035] - 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
[0036] - 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
[0037] 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.
[0038] The zone controller is generally located centrally in the vehicle, or at the very least, close to the other computers or electronic control units of the vehicle. Indeed, the zone controller communicates with the other computers or electronic control units of the vehicle via an Ethernet connection.
[0039] 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.
[0040] The zone controller la includes a microcontroller lal, an Ethernet interface la2 and a continuous 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").
[0041] Within the zone controller la, the microcontroller lal is connected via a data connection to the Ethernet interface la2, in particular an xMII (English acronym for "Media Independent Interface") or SPI (acronym English for “Serial Peripheral Interface”).
[0042] The Ethernet interface la2 is connected to the Ethernet connection 2 by a data connection 2a2 via an isolation means 2a21. The isolation means 2a21 is in particular of the capacitive type, for example an isolation capacitor for each conductor of the Ethernet connection 2.
[0043] The continuous power supply la3 supplies the Ethernet interface la2 and the microcontroller lai.
[0044] The continuous power supply la3 is also connected to the Ethernet connection 2 by a power connection 2a3 in order to provide power according to the PoDL standard (English acronym for "Power Over Data Lines", IEEE 802.3bu standard) via the Ethernet connection 2.
[0045] 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.
[0046] It is recalled that the PoDL power supply is a power supply on a pair of twisted connectors, superimposed on the voltage variations generated by the data transmission.
[0047] Each supervisory card 1b includes a data processing stage lb2 and a power supply stage lb3.
[0048] The data processing stage includes an Ethernet interface lb20 connected to the Ethernet connection 2 via an isolation means 2b21. The isolation means 2b21 is in particular of the capacitive type, for example an isolation capacitor for each conductor of the Ethernet connection 2.
[0049] The Ethernet interface lb20 is also 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 at least one cell supervisor lb22 and the Ethernet interface lb20, as well as any synchronization issues.
[0050] Each lb22 cell supervisor performs the supervision of a plurality of 11 battery cells.
[0051] The power supply stage lb3 connected to each supervisor lb22 comprises a DC-AC converter lb30, an isolation means lb31 and an AC-DC converter lb32. Figure [Fig.3] illustrates only the power supply stage of a supervisor card.
[0052] Although costly, supplying an lb32 AC-DC converter for each lb22 cell supervisor is particularly advantageous by allowing to provide the necessary power supply taking into account a different reference voltage for each lb32 AC-DC converter and indexed to the voltage of the monitored cells. Indeed, depending on their state of charge, the groups of cells constituting the power supply for CSCs in the state of the art vary between a few tens of volts and a few hundred volts.
[0053] In a first embodiment of a data processing stage, illustrated in Figure [Fig. 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.
[0054] 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.
[0055] 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.
[0056] Galvanic isolation lb23 of cell supervisors is achieved via a digital circuit, in particular of optical, capacitive, radio frequency or inductive type.
[0057] 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 (la) and at least two monitoring cards (1b), each monitoring card (1b) being designed to monitor at least one cell (11) of the traction battery through 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 (la2) and a continuous power supply (la3), the microcontroller (lal) being designed to control the Ethernet interface (la2) and the continuous power supply (la3), c. the continuous power supply (la3) being designed to power the Ethernet interface (la2) and the microcontroller (lal) of the zone controller (la), d. the continuous 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 stage, the data processing stage comprising an Ethernet interface (lb20) connected to the Ethernet connection (2) and to at least two cell supervisors (lb22) each designed to monitor at least one cell (11) of the battery, the power 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 supervisory card (1b) from the power supplied by the alternative power supply (la3).
2. Supervisory system according to claim 1, wherein the power supply stage comprises a DC-AC converter (lb30) connected in input to the Ethernet connection (2) via a power connection, and, for each cell supervisor (lb22) of the supervisor card, an isolation means (lb31) connected in series to an AC-DC converter (lb32).
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 is disposed between each Ethernet interface (la2, lb20) and the Ethernet connection (2).
5. . Supervisory system according to claim 4, wherein the isolation means is of a capacitive type, for example an isolation capacitor.
6. Supervisory system according to any one of claims 1 to 5, wherein the data processing stage includes a data buffer (lb21) connected between the Ethernet interface (lb20) and the cell supervisors (lb22).
7. Supervisory system according to claim 6, 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).
8. Supervisory system according to claim 7, wherein the first point-to-point connection is an SPI connection, the second point-to-point connection being a galvanically isolated SPI connection.
9. Supervisory system according to any one of claims 6 to 8, wherein, in a supervisory card (1b), the cell supervisors (lb22) are each connected to the data buffer (lb21) via a data bus.
10. Supervisory system according to claim 9, 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).