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

Abstract

A system for supervising cells (11) of an automobile battery, comprising a zone controller (1a) and at least two supervision cards (1b), connected via two Ethernet connections (2, 3), the supervision cards (1b) being connected to each other two by two via a third Ethernet connection (4), the zone controller (1a) comprises an AC power supply (1a3) providing power via an Ethernet connection (2), each supervision card (1b) comprises: a data processing stage comprising at least two cell supervisors (1b22) of at least one cell (11) and two Ethernet interfaces (1b20, 1b40) each connected to one of the Ethernet connections via a high-pass filter (1b19, 1b39), designed so as to allow only the voltage variations linked to the data to pass through while rejecting the supply voltage variations,a power supply stage connected to one of the Ethernet connections (2, 3) so as to power the supervision card (1b), a secondary AC power supply (1b33) providing power via an Ethernet connection between two supervision cards (1b), the AC power supplies (1a3, 1b33) having a power supply frequency significantly lower than the frequency linked to the data and so as to be able to be filtered by high-pass filtering. Figure for the abstract: Fig 2,

Description

Title of the invention: Automotive battery cell monitoring system, with independent power supply and point-to-point 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 two supervision cards via a first Ethernet connection and a second Ethernet connection, the supervision cards being connected to each other two by two via a third Ethernet connection,

[0018] b. the zone controller comprises a microcontroller, a first Ethernet interface, a second Ethernet interface and an AC power supply, the microcontroller being configured to control the Ethernet interfaces and the AC power supply,

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

[0020] d. the alternative power supply also being designed to provide power on a twisted pair of conductors via the first Ethernet connection between the zone controller and a supervisory card,

[0021] e. each supervision 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 power supply voltage variations, the data processing stage also comprising at least two cell supervisors each designed so as to monitor at least one cell of the battery,the power supply stage being connected to an Ethernet connection so as to provide power to each cell supervisor and to the Ethernet interfaces of the supervision card, ,

[0022] f. each supervision card comprising a secondary AC power supply designed to provide power on a pair of twisted conductors via an Ethernet connection between two supervision cards,

[0023] g. the AC power supplies being designed so that their supply frequency is chosen to be significantly lower than the frequency linked to the data and so as to be able to be filtered by the high-pass filters.

[0024] The power supply stage may comprise, for each cell supervisor, an isolation means connected on the one hand to an AC-DC converter and on the other hand 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 provided 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 provided between the first Ethernet connection and the AC power supply of each zone controller, an isolation means being provided between the third Ethernet connection and the auxiliary AC power supply of each supervision 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 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.

[0031] The first point-to-point connection may be an SPI connection, the second point-to-point connection being a galvanically isolated SPI connection.

[0032] In a supervisory board, 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, at least one of the cell supervisors being isolated from the data bus via an isolation capacitor. Brief description of the drawings

[0034] 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:

[0035] - figure [Fig.l] illustrates a CMS cell supervision system according to the state of prior art,

[0036] - Figure [Fig.2] illustrates the main elements of a monitoring system of cells according to the invention,

[0037] - 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,

[0038] - 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

[0039] - 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

[0040] The CMS cell supervision system according to the invention is referenced 1 on the figure [Fig.2]. It comprises a zone controller 1a connected to at least two supervision 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 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.

[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 range of the connections to the terminals of the cells.

[0043] The zone controller 1a comprises a microcontroller 1a1, a first Ethernet interface 1a2, a second Ethernet interface 1a4 and an AC power supply 1a3. By Ethernet interface, it is considered that it is a level 1 hardware interface in the OSI model (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 (acronym for “Media Independent Interface”) or SPI (acronym for “Serial Peripheral Interface”).

[0045] The first Ethernet interface 1a2 is connected to a first Ethernet connection 2 by a data connection 2a2 and an isolation means 2a21.

[0046] The second Ethernet interface 1a4 is connected to a second Ethernet connection 3 by a data connection 2a4 and an isolation means 2a41.

[0047] The AC power supply la3 supplies the first Ethernet interface la2, the second Ethernet interface la4 and the microcontroller la11 via an AC-DC converter not shown.

[0048] The alternative power supply la3 is furthermore connected to the first Ethernet connection 2 via a power connection 2a3 and an isolation means 2a31 and in order to achieve a power supply similar to the PoDL standard (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 the voltage variations linked to the transmission of data from the voltage variations linked to the power supply, the frequency of the alternating power supply is chosen so as to be significantly lower than the frequency linked to the transmission of data, and so that it can be filtered by frequency filtering (for example, data at a frequency of 12MHz, power supply at a frequency lower than 1kHz).

[0051] 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.

[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 supervision card 1b comprises 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, 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 lb19 and lb39 are designed to separate the voltage variations linked to the transmission of the data from the voltage variations linked to the alternating power supply.

[0055] The Ethernet interfaces lb20 and lb40 are both connected to the same 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 interfaces lb20 and lb40 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 interfaces lb20, lb40, as well as the management of any possible asynchronicity.

[0056] Each lb22 cell supervisor carries out the supervision of a plurality of battery cells 11. Each data processing stage can comprise up to eight lb22 cell supervisors.

[0057] The power supply stage lb3 comprises a power supply connection to each cell supervisor lb22 provided 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 expensive, the provision of an AC-DC converter lb32 for each cell supervisor lb22 is particularly advantageous in making it possible to provide the necessary supply power taking into account a different reference voltage for each AC-DC converter lb32 and indexed to the voltage of the monitored cells.

[0059] Each supervision card is provided 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 provide power supply in a manner similar to the AC power supply la3 of the zone controller.

[0060] The supervision cards 1b are connected two by two by a third Ethernet connection 4, allowing data to be exchanged bidirectionally and power to be supplied to a supervision card by an immediately adjacent supervision card.

[0061] The last supervision card is connected by a first high-pass filter and a first Ethernet interface to a third Ethernet connection and by 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 fault in a supervision card upstream of the last supervision card, such a connection via the second Ethernet connection 3 makes it possible to route the information from all the supervision cards between the faulty card and the last supervision card so as not to lose access to the cells monitored by these cards.

[0063] It will be noted that there is no mention of the presence of a secondary power supply in the last supervision 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 interests of standardization of components, the last supervision 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 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).

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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 two supervision cards (1b) via a first Ethernet connection (2) and a second Ethernet connection (3), the supervision cards (1b) being connected to each other two by two 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 AC power supply (la3), the microcontroller (lal) being designed to control the Ethernet interfaces (Ia2,la4) and the AC power supply (la3), c. the alternative power supply (la3) being designed to supply the Ethernet interfaces (Ia2,la4) and the microcontroller (lal) of the zone controller (la), d. the alternative power supply (la3) also being designed to provide power on a twisted pair of conductors via the first Ethernet connection (2) between the zone controller (la) and a supervision card (1b), e. each supervision 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 means (2b21) and a first high-pass filter (1b 19) and a second Ethernet interface (lb40) connected to another of the Ethernet connections via a second isolation means (2b41) and a second high-pass filter (lb39), the high-pass filters (1b 19, lb39) being designed so as to allow only voltage variations to pass through the Ethernet interface (lb20, lb40) linked 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 supply 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 supervision card (1b), f. each supervision card comprising a secondary AC power supply (lb33) designed to provide power on a twisted pair of conductors via an Ethernet connection between two supervision cards (1b), g.the alternative power supplies (Ia3,lb33) being designed so that their power supply frequency is chosen to be significantly lower than the frequency linked to the data and so as to be able to be filtered by the high-pass filters.

2. Supervision system according to claim 1, in which the power supply stage comprises, for each cell supervisor (lb22), an isolation means (lb31) connected on the one hand to an AC-DC converter (lb32) and on the other hand to the Ethernet connection (2) via a power supply connection.

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 (2a21, 2b21, 2b41) is arranged between the Ethernet interfaces (Ia2, 1a4) and the Ethernet connections (2, 3) as well as between the high-pass filters (Ibl9, 1b39) and the Ethernet connections (2, 3, 4).

5. Supervision system according to claim 4, in which an isolation means (2a31) is arranged between the first Ethernet connection (2) and the alternating current supply (1a3) of each zone controller (la), an isolation means (2b34) being arranged between the third Ethernet connection (4) and the auxiliary alternating current supply (lb33) of each supervision card.

6. Supervision system according to claim 4 or 5, in which an isolation means (2a21, 2a41, 2a31, 2b21, 2b41, 2b34) is of the inductive type, in particular an isolation transformer.

7. Supervision system according to any one of claims 1 to 6, wherein the data processing stage comprises a data buffer (lb21) connected between the Ethernet interfaces (lb20, lb40) and the cell supervisors (lb22).

8. Supervision system according to claim 7, 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).

9. A monitoring 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. Supervision system according to any one of claims 7 to 9, wherein, in a supervision card (1b), the cell supervisors (lb22) are each connected to the data buffer (lb21) via a data bus.

11. Supervision system according to claim 10, 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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