System for supervising motor-vehicle battery cells, with an independent ac power supply and 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 by an Ethernet connection (2), wherein: a. the zone controller (1a) comprises an AC power supply (1a3) that supplies power via an Ethernet connection (2) between the zone controller (1a) and the supervision boards (1b), at a chosen frequency significantly lower than the data-related frequency so as to be able to be filtered by high-pass filtering, b. each supervision board (1b) comprising: i. a data processing stage comprising at least two cell supervisors (1b22) each designed to monitor at least one cell (11) and an Ethernet interface (1b20) connected to an isolation means (2b21) and a high-pass filter (1b19) for the power of the AC power supply (1a3), ii. a power supply stage connected to the Ethernet connection (2) so as to provide a supply of power to each cell supervisor (1b22) and to the Ethernet interface (1b20) of the supervision board (1b) from the power of the AC power supply (1a3).

Description

[0001] DESCRIPTION

[0002] AUTOMOTIVE BATTERY CELL MONITORING SYSTEM WITH INDEPENDENT ALTERNATIVE POWER SUPPLY AND ETHERNET COMMUNICATION

[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 CSC cell sensor circuits are required to monitor all the cells in a battery.

[0009] These CSC cell sensor circuits are connected in a daisy chain, i.e. via isolated point-to-point communication buses (capacitive coupling or transformer isolation). One of the CSC cell sensor circuits interfaces 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 since data from the other CSC cell sensor circuits pass through it before reaching the external microcontroller. Each CSC cell sensor circuit is powered directly by the battery cells being monitored. Since the cells of a battery are connected in series, the failure of one cell causes all 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 is faulty.

[0010] In addition, the unpowered cell sensor circuit C SC can no longer act as a relay for information determined by the other cell sensor circuits C SC located downstream of the connection to the master controller. This means that access to all cell sensor circuits C SC is lost from the faulty cell sensor circuit.

[0011] It should be noted that in some cases, a backup master controller, arranged last in the chain of cell sensor circuits CSC relative to the master controller, is provided, which makes it possible to reverse the direction of the chain connection and regain access to the cell sensor circuits C SC which could no longer be accessed via the master controller. Even in this case, the cell sensor circuit C SC 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.

[0012] There are obviously a number of problems with such a battery management system.

[0013] 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.

[0014] A second problem is related to the difficulty of determining which battery cell is faulty in the event of a CSC cell sensor circuit power supply failure. Since voltage and current measurements from 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.

[0015] 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 cell sensor circuit chain C SC to be reversed.

[0016] A fourth problem is related to the significant consumption of the CSC cell sensor circuits contributing to the discharge of the battery.

[0017] A fifth problem is related to the fact that so-called "daisy chain" 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 monitor at least one cell of the traction battery through voltage measurements, in which: a. the zone controller is connected to the supervision cards via an Ethernet connection, b. the zone controller comprises a microcontroller, an Ethernet interface and an AC power supply, the microcontroller being designed to control the Ethernet interface and the AC power supply, c. the AC power supply being designed to power the Ethernet interface and the microcontroller of the zone controller, d.the alternative 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, 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 via an isolation means and a high-pass filter designed so as to allow only voltage variations linked to the data to pass through the Ethernet interface while rejecting voltage variations linked to the AC power supply, 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 the Ethernet connection so as to provide power to each cell supervisor and to the Ethernet interface of the supervision card.

[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 the Ethernet interface and the Ethernet connection as well as between the high-pass filter and the Ethernet connection.

[0024] An isolation means may be of the inductive type, in particular an isolation transformer.

[0025] An isolation means may be provided between the Ethernet connection and the power supply stage of each supervisory card, the isolation means of the data processing stage and the isolation means of the power supply stage being coupled together, the isolation means of the Ethernet interface and the isolation means of the AC power supply of the zone controller also being coupled together.

[0026] The data processing stage may comprise a data buffer connected between the Ethernet interface and the cell supervisors. In a supervisor card, 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 being each connected to their nearest neighbor by a second point-to-point connection, so that the data transmitted by a cell supervisor passes from one to the next to the data buffer.

[0027] The first point-to-point connection can be an SPI connection, with the second point-to-point connection being a galvanically isolated SPI connection.

[0028] In a supervisory board, cell supervisors can each be connected to the data buffer via a data bus.

[0029] 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.

[0030] 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 1] illustrates a CMS cell supervision system according to the prior art,

[0033] - figure [Fig 2] illustrates the main elements of a cell supervision system 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 data processing stage of a supervision card included in a first embodiment of a cell supervision system according to the invention, - 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, and

[0036] - figure [Fig 6] illustrates the main elements of a cell supervision system according to a second embodiment of the invention.

[0037] Detailed description

[0038] 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 802.3 cg standard, for support of the 10BASE-T 1 S communication protocol, using a pair of twisted conductors.

[0039] 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.

[0040] 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.

[0041] The zone controller la includes a microcontroller l al , an Ethernet interface l a2 and an AC power supply l a3. An Ethernet interface is considered to be a level 1 hardware interface in the OSI model (an acronym for "Open System Interconnection").

[0042] Within the zone controller la, the microcontroller l al is connected by a data connection to the Ethernet interface l a2, in particular a connection of type xMII (acronym for "Media Independent Interface") or SPI (acronym for "Serial Peripheral Interface"). The Ethernet interface l a2 is connected to the Ethernet connection by a data connection 2a2 and an isolation means 2a21.

[0043] The AC power supply 1 a3 supplies the Ethernet interface 1 a2 and the microcontroller 1 a3 via an AC-DC converter (not shown). The AC power supply 1 a3 is further connected to the Ethernet connection 2 via a power connection 2a3 and an isolation means 2a3 1 , in order to provide power supply similar to the PoDL standard (acronym for "Power Over Data Lines", IEEE 802.3bu standard) via the Ethernet connection 2.

[0044] The isolation means 2a21 and 2a31 are in particular of the inductive type, for example an isolation transformer.

[0045] 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 1 a3 is chosen so as to be significantly lower than the frequency linked to the transmission of data, and so that the voltage variations linked to the power supply can be filtered by frequency filtering (for example, data at a frequency of 12 MHz, power supply at a frequency lower than 1 kHz).

[0046] 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.

[0047] The proposed power supply is a power supply on a pair of twisted connectors, superimposed on the voltage variations generated by data transmission.

[0048] Each 1b supervision card includes a data processing stage and a lb3 power supply stage.

[0049] The data processing stage comprises 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 lb19 is designed to separate the voltage variations linked to the data from the voltage variations linked to the AC power supply 1a3 and to only allow the voltage variations linked to the data to pass through. The isolation means 2b21 is in particular of the inductive type, for example an isolation transformer.

[0050] The Ethernet interface lb20 is 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 1 b21 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 asynchronicity.

[0051] Each lb22 cell supervisor supervises a plurality of 1 1 battery cells.

[0052] The power supply stage lb3 comprises a power supply connection to each cell supervisor lb22 provided with an isolation means lb3 1 and an AC-DC converter lb32. Figure [Fig 3] illustrates the power supply stage of a supervisory card.

[0053] 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.

[0054] 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.Such an embodiment is close to the state of the art, while simplifying 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 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.

[0056] 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.

[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.

[0058] In a second embodiment of the CMS cell supervision system illustrated by the figure [Fig 6], the isolation means 2a21 and 2a3 1 are connected respectively to the AC power supply 1a3 and to the Ethernet interface 1a2 of the zone controller 1a by a first winding, as in the first embodiment. The second winding of the isolation means 2a3 1 and the second winding of the isolation means 2a21 are connected to the Ethernet connection 2 and coupled together by a link 4a. At each power supply stage of a supervision card 1b, an isolation means 2b31 is added at each power supply stage between the power supply connection 2b3 to the Ethernet connection and the isolation means 1b31. The isolation means 2b31 is in particular of the inductive type, for example an isolation transformer.

[0059] The isolation means 2b21 and 2b31 are connected respectively to the high-pass filter lbl9 and to the isolation means lb31 of each supervision card 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 reasons of practicality, the two windings can be grouped in the same component with a common midpoint referenced 4b. Compared to the first embodiment of the CMS cell supervision system, the grouping of the isolation means within the same component makes it possible to optimize its size and cost.

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 the supervision cards (1b) via an Ethernet connection (2), b. the zone controller (la) comprises a microcontroller (lal), an Ethernet interface and an AC power supply (la3), the microcontroller (lal) being designed to control the Ethernet interface (la2) and the AC power supply (la3), c. the AC power supply (la3) being designed to power the Ethernet interface (la2) and the microcontroller (lal) of the zone controller (la), d.the AC 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 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 (1b 19) designed to allow only voltage variations related to the data to pass through the Ethernet interface (lb20) while rejecting voltage variations related to the AC power supply (la3), the data processing stage also comprising at least two supervisors. of cells (lb22) each designed so as to carry out the monitoring of 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 supervision card (1b) from the power supplied by the AC power supply (la3), f. the AC power supply (la3) being designed so that the 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) is arranged between the Ethernet interface (la2) and the Ethernet connection (2) as well as between the high-pass filter (lb 19) and the Ethernet connection (2).

5. Supervision system according to claim 4, in which an isolation means (2a21, 2b21, 2b31) is of the inductive type, in particular an isolation transformer.

6. Supervision system according to claim 5, in which an isolation means (2b31) is arranged between the Ethernet connection and the power supply stage of each supervision 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 AC power supply of the zone controller also being coupled together.

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

8. Supervision system according to claim 7, in which, in a supervision card (1b), the cell supervisors (1 b22) 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) transits from near to far 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 by means of an isolation capacitor (lb23).

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