Automotive battery cell monitoring system with independent power supply and Ethernet communication

Abstract

A system for supervising cells (11) of an automotive battery, comprising a zone controller (1a) and at least two supervision cards (1b) connected by an Ethernet connection (2), wherein: the zone controller (1a) comprises a DC power supply (1a3), designed to provide power on a pair of twisted conductors via the Ethernet connection (2) between the zone controller (1a) and the supervision cards (1b), each supervision card (1b) comprising: a data processing stage comprising an Ethernet interface (1b20) connected to the Ethernet connection (2) and to the at least two supervisors (1b22) each designed to monitor at least one cell (11) of the battery,a power supply stage being connected to the Ethernet connection (2) so as to provide power to each cell supervisor (1b22) and to the Ethernet interface (1b20) of the supervision card (1b) from the power supplied by the DC power supply (1a3). Figure for abstract: Fig 2,

Description

Title of the invention: Automotive battery cell monitoring system, with independent power supply and Ethernet communication Technical field

[0001] The technical field of the invention is battery management, and more particularly battery management based on cell sensor circuits. Previous techniques

[0002] A battery generally comprises a number of battery cells, for example 24 battery cells.

[0003] In order to monitor such batteries, a CMS cell supervision system (acronym for "Cell Management System") is used. The CMS cell supervision system comprises at least one CSC cell sensor circuit (acronym for "Cell Sensor Circuit") responsible for monitoring at least one cell 11 of battery 10. Figure [Fig.l] illustrates such a system.

[0004] Cell monitoring means 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, i.e. via isolated point-to-point communication buses (isolation by capacitive coupling or by transformers). One of the CSC cell sensor circuits provides the interface with an external microcontroller ensuring communication with the rest of the vehicle. The CSC cell sensor circuit connected to the external microcontroller acts as a master controller insofar as the data from the other CSC cell sensor circuits pass through it before reaching the external microcontroller.

[0006] Each CSC cell sensor circuit is powered directly by the monitored battery cells. Since the cells of a battery are connected in series, the failure of one cell causes all of 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 not possible to know which battery cell has failed.

[0007] In addition, the unpowered CSC cell sensor circuit can no longer act as a relay for the information determined by the other CSC cell sensor circuits arranged downstream of the connection to the master controller. This means that access to all the CSC cell sensor circuits is lost from the de- powered cell sensor circuit. failing.

[0008] It will be noted that, in certain cases, a backup master controller, arranged last in the chain of CSC cell sensor circuits relative to the master controller, is provided, which makes it possible to reverse the direction of the chain connection and to regain access to the CSC cell sensor circuits which could no longer be accessed via the master controller. Even in this case, it is still not possible to access the CSC cell sensor circuit normally powered by the group of cells comprising the faulty cell. In addition, 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 linked to the failure of the power supply of a CSC cell sensor circuit which makes the monitoring of all the monitored cells inoperative.

[0011] A second problem is related to the difficulty of determining which battery cell is faulty in the event of a failure of the power supply to a CSC cell sensor circuit. Since the voltage and current measurements of the different cells are no longer available, it is not possible to determine which faulty cell(s) need to be replaced. It is then necessary to replace all the cells or to test them one by one. In both cases, the repair is not economically efficient.

[0012] A third problem is related to the increase in complexity of a battery management system equipped with a backup controller allowing the interrogation direction of the CSC cell sensor circuit chain to be reversed.

[0013] A fourth problem is linked to the significant consumption of the CSC cell sensor circuits contributing to the discharge of the battery.

[0014] A fifth problem is linked to the fact that so-called “daisy chain” type communication is not standardized and becomes a barrier to the interoperability of solutions.

[0015] The present invention aims to respond to these various technical problems. Statement of the invention

[0016] The subject of the invention is a system for supervising cells of a motor vehicle traction battery, comprising a zone controller and at least two supervision cards, each supervision card being designed so as to carry out the monitoring of at least one cell of the traction battery through voltage measurements, in which:

[0017] a. the zone controller is connected to the supervision cards via an Ethernet connection,

[0018] b. the zone controller comprises a microcontroller, an Ethernet interface and a DC power supply, the microcontroller being configured to control the interface Ethernet and continuous power supply,

[0019] c. the DC power supply being designed to power the Ethernet interface and the microcontroller of the zone controller,

[0020] d. the DC power supply also being designed to provide power on a twisted pair of conductors via the Ethernet connection between the zone controller and the supervision cards,

[0021] e. each supervision 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 the at least two cell supervisors each designed to carry out the monitoring of 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 supervision card.

[0022] The power supply stage may comprise a DC-AC converter connected at the input to the Ethernet connection via a power supply connection, and, for each cell supervisor of the supervision card, 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 provided between each Ethernet interface and the Ethernet connection.

[0025] The isolation means may be of the capacitive type, for example an isolation capacitor.

[0026] The data processing stage of a supervisory card may comprise 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 each being connected to their nearest neighbor by a second point-to-point connection, so that the data transmitted by a cell supervisor transits from near to far to the data buffer.

[0028] The first point-to-point connection may be an SPI connection, the second point-to-point connection being a galvanically isolated SPI connection.

[0029] In a supervisory board, 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, at least one of the cell supervisors being isolated from the data bus via an isolation capacitor. Brief description of the drawings

[0031] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0032] - figure [Fig.l] illustrates a CMS cell supervision system according to the state of prior art,

[0033] - Figure [Fig.2] illustrates the main elements of a monitoring system of cells according to the invention,

[0034] - Figure [Fig.3] illustrates the main elements of a power supply stage of a supervision card included in a cell supervision system according to the invention,

[0035] - Figure [Fig.4] illustrates the main elements of a processing stage of data from a supervision card included in a first embodiment of a cell supervision system according to the invention, and

[0036] - Figure [Fig.5] illustrates the main elements of a processing stage of data from a supervision card according to a second embodiment of a cell supervision system according to the invention. Detailed description

[0037] The CMS cell supervision system according to the invention is referenced 1 in the figure [Fig.2]. It comprises a zone controller 1a connected to at least two supervision 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 1a is generally arranged centrally in the vehicle, at least close to the other computers or electronic control units of the vehicle. In fact, 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 range of the connections to the terminals of the cells.

[0040] The zone controller 1a comprises a microcontroller 1a1, an Ethernet interface 1a2 and a DC power supply 1a3. By Ethernet interface, we consider that it is a level 1 hardware interface in the OSI model (acronym for "Open System Interconnection").

[0041] Within the zone controller la, the microcontroller lal is connected by a data connection to the Ethernet interface la2, in particular a connection of the xMII type (acronym for "Media Independent Interface") or SPI (acronym English for “Serial Peripheral Interface”).

[0042] The Ethernet interface 1a2 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 DC power supply la3 supplies the Ethernet interface la2 and the microcontroller lai.

[0044] The continuous power supply la3 is furthermore connected to the Ethernet connection 2 by a power connection 2a3 in order to provide power supply according to the PoDL standard (acronym for “Power Over Data Lines”, IEEE 802.3bu standard) via the Ethernet connection 2.

[0045] Each supervisory card 1b comprises a data connection 2b2 and a power connection 2b3 to the Ethernet connection, each presented in the form of 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 supervision card 1b comprises a data processing stage lb2 and a power supply stage lb3.

[0048] The data processing stage comprises 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 ("buffer" in English) itself connected to at least one cell supervisor lb22 by a serial communication connection of the SPI type. In a particular embodiment, the data buffer lb21 is connected to the Ethernet interface lb20 by 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 interface lb20, as well as the management of any possible synchronicity.

[0050] Each cell supervisor lb22 carries out the supervision of a plurality of battery cells 11.

[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 expensive, the provision of an lb32 AC-DC converter for each lb22 cell supervisor is particularly advantageous in allowing 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 source of the 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 by the figure [Fig.4], a first cell supervisor is connected to the data buffer lb21 by a first SPI serial communication connection. The first cell supervisor is then connected to a second cell supervisor by a second ISO SPI serial communication connection. By ISO SPI connection is meant an SPI serial connection comprising galvanic isolation. Each of the other cell supervisors is connected to a single other cell supervisor by an ISO SPI serial communication connection, so as to form a chain (“daisy chain” in English).

[0054] Such an embodiment is close to the state of the art, while simplifying the data connections due to the use of SPI and ISO SPI serial communication connections and solving the power supply problems of 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 by 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 a galvanic isolation lb23 at its connection with the SPI data bus. The galvanic isolation of the first cell supervisor can be omitted because it is powered by the same power 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] The galvanic isolation lb23 of the cell supervisors is achieved by means of a digital circuit, in particular of the optical, capacitive, radiofrequency or inductive type.

[0057] This embodiment has the advantage of improving the robustness of the supervision card by making the communication between the data buffer and the cell supervisors independent of the operation of each cell supervisor. In the event of a fault in one of the cell supervisors, the other cell supervisors remain accessible.

Claims

Claims

1. System for supervising cells (11) of a motor vehicle traction battery, comprising a zone controller (1a) and at least two supervision cards (1b), each supervision card (1b) being designed to carry out the monitoring of at least one cell (11) of the traction battery through voltage measurements, characterized in that: a. the zone controller (la) is connected to the supervision cards (1b) via an Ethernet connection (2), b. the zone controller (la) comprises a microcontroller (lal), an Ethernet interface (la2) and a DC power supply (la3), the microcontroller (lal) being designed to control the Ethernet interface (la2) and the DC power supply (la3), c. the DC power supply (la3) being designed to supply the Ethernet interface (la2) and the microcontroller (lal) of the zone controller (la), d. the DC power supply (la3) also being designed to provide power on a twisted pair of conductors via the Ethernet connection (2) between the zone controller (la) and the supervision cards (1b), e. each supervision 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) and to the at least two cell supervisors (lb22) each designed to carry out the monitoring of 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 supervision card (1b) from the power supplied by the AC power supply (la3).

2. Supervision system according to claim 1, in which the power supply stage comprises a direct-alternating converter (lb30) connected as input to the Ethernet connection (2) via a power supply connection, and, for each cell supervisor (lb22) of the supervision card, an isolation means (lb31) connected in series to an AC-DC converter (lb32).

3. Supervision system according to claim 2, in which the isolation means (lb31) is of the inductive type, in particular an isolation transformer.

4. Supervision system according to any one of claims 1 to 3, in which an isolation means is arranged between each Ethernet interface (la2, lb20) and the Ethernet connection (2).

5. . Supervision system according to claim 4, in which the isolation means is of the capacitive type, for example an isolation capacitor.

6. Supervisory system according to any one of claims 1 to 5, wherein the data processing stage comprises a data buffer (lb21) connected between the Ethernet interface (lb20) and the cell supervisors (lb22).

7. Supervision system according to claim 6, wherein, in a supervision 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 each connected to their nearest neighbor by a second point-to-point connection, so that the data transmitted by a cell supervisor (lb22) transits from near to far to the data buffer (lb21).

8. A monitoring 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. Supervision system according to any one of claims 6 to 8, wherein, in a supervision card (1b), the cell supervisors (lb22) are each connected to the data buffer (lb21) via a data bus.

10. Supervision system according to claim 9, in which the data bus is of the SPI type, at least one of the cell supervisors (lb22) being isolated from the data bus via an isolation capacitor (lb23).

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