System for supervising motor-vehicle battery cells, with an independent power supply and point-to-point ethernet communication

Abstract

The invention relates to a system for supervising cells (11) of a motor-vehicle battery, the system comprising a zone controller (1a) and at least two supervision boards (1b), the zone controller and supervision boards being connected via two Ethernet connections (2, 3), the supervision boards (1b) being connected to one another in pairs via a third Ethernet connection (4), the zone controller (1a) comprising an AC power supply (1a3) that supplies power via an Ethernet connection (2), a. each supervision board (1b) comprises: i. a data-processing stage comprising at least two cell supervisors (1b22) for 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 data-related voltage variations to pass while rejecting supply voltage variations, ii. a power supply stage connected to one of the Ethernet connections (2, 3) so as to supply power to the supervision board (1b), iii. a secondary AC power supply (1b33) that supplies power via an Ethernet connection between two supervision boards (1b), b. the AC power supplies (1a3, 1b33) having a supply frequency significantly lower than the data-related frequency so as to be able to be filtered by high-pass filtering.

Description

[0001] Automotive battery cell monitoring system with independent power supply and point-to-point Ethernet communication

[0002] DESCRIPTION

[0003] Technical field

[0004] The technical field of the invention is battery management, and more particularly battery management based on cell sensor circuits.

[0005] Previous techniques

[0006] A battery pack usually consists of a number of battery cells, for example 24 battery cells.

[0007] 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 1] illustrates such a system.

[0008] Cell monitoring means determining the voltage across each cell. Multiple cell sensor circuits C SC are required to monitor all the cells in a battery.

[0009] These C SC cell sensor circuits are connected in a chain ("daily chain" in English), that is to say via isolated point-to-point communication buses (isolation by capacitive coupling or by transformers). One of the C SC 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.

[0010] Each CSC cell sensor circuit is powered directly by the battery cells being monitored. Since the cells in a battery are connected in series, the failure of one cell causes the entire cell 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 determine which battery cell has failed.

[0011] In addition, 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. This means that access to all CSC cell sensor circuits is lost from the faulty cell sensor circuit.

[0012] It should be noted that in some cases, a backup master controller, placed 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 regain access to the CSC cell sensor circuits that could no longer be accessed via the master controller. Even in this case, the CSC cell sensor circuit normally powered by the group of cells including the faulty cell still cannot be accessed. In addition, the presence of such a backup master controller increases the cost of a battery management system.

[0013] There are obviously a number of problems with such a battery management system.

[0014] A first problem is linked to the failure of the power supply of a cell sensor circuit C SC which makes the monitoring of all the monitored cells inoperative.

[0015] A second problem is related to the difficulty of determining which battery cell is faulty in the event of a C SC cell sensor circuit power supply failure. Since the voltage and current measurements of the individual 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.

[0016] A third problem is related to the increased 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.

[0017] A fourth problem is related to the significant consumption of the CSC cell sensor circuits contributing to battery discharge. A fifth problem is related to the fact that the so-called "daisy chain" type communication is not standardized and becomes an obstacle to the interoperability of solutions.

[0018] The present invention aims to respond to these various technical problems.

[0019] Statement of the invention

[0020] The invention relates to 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 to carry out the monitoring of at least one cell of the traction battery through voltage measurements, in which: 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, b. the zone controller comprises a microcontroller, a first Ethernet interface, a second Ethernet interface and an AC power supply, the microcontroller being designed to control the Ethernet interfaces and the AC power supply,c. the AC power supply being designed to power the Ethernet interfaces and the microcontroller of the zone controller, d. the AC 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, 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 only allow 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 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, f. each supervision card comprising a secondary AC power supply designed so as to provide power on a pair of twisted conductors via an Ethernet connection between two supervision cards,g. the AC power supplies being designed so that their power supply frequency is chosen to be significantly lower than the data-related frequency and so as to be able to be filtered by the high-pass filters.,

[0021] 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.

[0022] The isolation means may be of the inductive type, in particular an isolation transformer.

[0023] An isolation means may be provided between Ethernet interfaces and Ethernet connections as well as between high-pass filters and Ethernet connections.

[0024] 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 supervisory card.

[0025] An isolation means may be of the inductive type, in particular an isolation transformer.

[0026] The data processing stage may include a data buffer connected between the Ethernet interfaces and the cell supervisors.

[0027] In a supervisory board, the cell supervisors may 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 passes from near to far to the data buffer.

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

[0029] In a supervisory board, 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 capacitor.

[0031] Brief description of the drawings

[0032] 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:

[0033] - figure [Fig 1] illustrates a CMS cell supervision system according to the prior art,

[0034] - figure [Fig 2] illustrates the main elements of a cell supervision system according to the invention,

[0035] - 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,

[0036] - figure [Fig 4] illustrates the main elements of a data processing stage of a supervision card included in a first embodiment of a cell supervision system according to the invention, and

[0037] - figure [Fig 5] illustrates the main elements of a data processing stage of a supervision card according to a second embodiment of a cell supervision system according to the invention.

[0038] Detailed description

[0039] 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 two Ethernet connections referenced 2 and 3. The Ethernet connections are in particular connections according to the IEEE 802.3 cg standard, for support of the 10BASE-T 1S communication protocol, using a pair of twisted conductors.

[0040] The zone controller is usually located centrally in the vehicle, at least close to the other computers or electronic control units in the vehicle. In fact, the zone controller communicates with the other computers or electronic control units in the vehicle via an Ethernet connection.

[0041] 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 connections to the terminals of the cells.

[0042] The zone controller la comprises a microcontroller l al , a first Ethernet interface l a2, a second Ethernet interface l a4 and an AC power supply l a3. By Ethernet interface, we consider that it is a level 1 hardware interface in the O SI model (acronym for "Open System Interconnection").

[0043] Within the zone controller la, the microcontroller l al is connected by a data connection to the first Ethernet interface l a2 and to the second Ethernet interface l a4, in particular a connection of type xMII (acronym for "Media Independent Interface") or SPI (acronym for "Serial Peripheral Interface").

[0044] The first Ethernet interface 1a2 is connected to a first Ethernet connection 2 by a data connection 2a2 and an isolation means 2a21.

[0045] The second Ethernet interface 1a4 is connected to a second Ethernet connection 3 by a data connection 2a4 and an isolation means 2a41.

[0046] The AC power supply l a3 supplies the first Ethernet interface l a2, the second Ethernet interface l a4 and the microcontroller l a1 via an AC-DC converter not shown.

[0047] The AC power supply 1a3 is furthermore connected to the first Ethernet connection 2 via a power connection 2a3 and an isolation means 2a3 1 and in order to provide a power supply similar to the PoDL standard (acronym for "Power Over Data Lines", IEEE 802.3bu standard) via the Ethernet connection 2. The isolation means 2a21, 2a41 and 2a3 1 are in particular of the inductive type, for example isolation transformers.

[0048] 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 data transmission, and so as to be able to be filtered by frequency filtering (for example, data at a frequency of 12 MHz, power supply at a frequency lower than 1 kHz).

[0049] Each 1b supervisor card includes a 2b2 data connection and a 2b3 power connection to the Ethernet connection, each presented as a pair of conductors.

[0050] The proposed power supply is a power supply on a twisted pair of connectors, superimposed on the voltage variations generated by data transmission.

[0051] Each 1 b supervision card includes a data processing stage and a lb3 power supply stage.

[0052] 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 data from the voltage variations linked to the alternating power supply.

[0053] 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 an SPI type serial communication connection. 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.

[0054] Each cell supervisor lb22 carries out the supervision of a plurality of battery cells 1 1. Each data processing stage can comprise up to eight cell supervisors lb22. The power supply stage lb3 comprises a power connection to each cell supervisor lb22 provided with an isolation means lb3 1 and an AC-DC converter l b32. Figure [Fig 3] illustrates the power supply stage lb3 of a supervision card.

[0055] Although expensive, the provision of an lb32 AC-DC converter for each lb22 cell supervisor is particularly advantageous in that it makes it possible to provide the necessary supply power taking into account a different reference voltage for each lb32 AC-DC converter and indexed to the voltage of the monitored cells.

[0056] Each supervision card is provided with a secondary power supply lb33 connected by an isolation means to the third Ethernet connection 4 via an isolation means 2b34, in order to provide power supply in a similar manner to the alternative power supply l a3 of the zone controller.

[0057] 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.

[0058] 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 1 a4 of the zone controller 1 a.

[0059] 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.

[0060] It should be noted that the presence of a secondary power supply in the last supervision card is not mentioned. 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. However, for the sake of standardization of components, the last supervision card may include a secondary power supply, which then remains unconnected to the second Ethernet connection 3.

[0061] In a first embodiment of a data processing stage, illustrated in [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 only one other cell supervisor by an ISO SPI serial communication connection, so as to form a daisy chain.

[0062] 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.

[0063] 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 with the SPI data bus. The galvanic isolation of the first cell supervisor can be omitted since 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.

[0064] The lb23 galvanic isolation of the cell supervisors is achieved by means of a digital circuit, in particular of the optical, capacitive, radiofrequency or inductive type.

[0065] 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 (la) and at least two supervision cards (1b), each supervision 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 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 power to 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 (lb), e.each supervision card (lb) 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 (lb 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 (1b19, 1b39) being designed so as to allow only the voltage variations linked to the to pass through the Ethernet interface (lb20, lb40). 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 AC 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 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, Ia4) and the Ethernet connections (2, 3) as well as between the high-pass filters (Ib 19, Ib39) 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 (la3) 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, 1 b40) and the cell supervisors (lb22).

8. Supervision system according to claim 7, in which, in a supervision card (1b), the cell supervisors (1b22) form a chain in which the first cell supervisor (1b22) is connected by a first point-to-point connection to the data buffer (1b21) and by another point-to-point connection to another cell supervisor (1b22), the other cell supervisors (1b22) being each connected to their nearest neighbor by a second point-to-point connection, so that the data transmitted by a cell supervisor (1b22) pass from close to close to the data buffer (1b21).

9. Supervision 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, in which, in a supervision card (1b), the cell supervisors (lb22) are each connected to the data buffer (lb21) via a data bus. 1 1. 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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