Automotive battery cell monitoring system with independent AC power supply and 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 by an Ethernet connection (2), wherein: the zone controller (1a) comprises an AC power supply (1a3) providing power via an Ethernet connection (2) between the zone controller (1a) and the supervision cards (1b), at a frequency chosen to be significantly lower than the frequency linked to the data so as to be able to be filtered by a high-pass filtering, each supervision card (1b) comprising: a data processing stage comprising at least two cell supervisors (1b22) each designed to carry out the monitoring of at least one cell (11) and an Ethernet interface (1b20) connected to an isolation means (2b21) and a high-pass filter (1b19) of the power of the AC power supply (1a3),a power supply stage 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 of the alternative power supply (1a3). Figure for abstract: Fig 2,

Description

Title of the invention: Automotive battery cell monitoring system, with independent AC 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 an AC power supply, the microcontroller being configured to control the interface Ethernet and AC power,

[0019] c. the AC power supply being designed to power the Ethernet interface 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 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 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.

[0022] 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.

[0023] The isolation means may be of the inductive type, in particular an isolation transformer.

[0024] 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.

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

[0026] An isolation means may be arranged 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.

[0027] The data processing stage may include a data buffer connected between the Ethernet interface and the cell supervisors.

[0028] 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 passes from one to the next. to the data buffer.

[0029] The first point-to-point connection may be an SPI connection, the second point-to-point connection being a galvanically isolated SPI connection.

[0030] In a supervisory board, the cell supervisors can each be connected to the data buffer via a data bus.

[0031] 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

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

[0034] - Figure [Fig.2] illustrates the main elements of a monitoring system of cells 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 processing stage of data from a supervision card included in a first embodiment of a cell supervision system according to the invention,

[0037] - 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, and

[0038] - Figure [Fig.6] illustrates the main elements of a monitoring system of cells according to a second embodiment of the invention. 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 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.

[0040] 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.

[0041] In contrast, the supervision cards 1b are arranged on the battery 10, at most close to the monitored cells 11, for reasons of cost and range of connections to the cell terminals.

[0042] The zone controller 1a comprises a microcontroller 1a1, an Ethernet interface 1a2 and an AC 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").

[0043] Within the zone controller la, the microcontroller lal is connected by a data connection to the Ethernet interface la2, in particular a connection of type xMII (English acronym for “Media Independent Interface”) or SPI (English acronym for “Serial Peripheral Interface”).

[0044] The Ethernet interface la2 is connected to the Ethernet connection by a data connection 2a2 and an isolation means 2a21.

[0045] The AC power supply la3 supplies the Ethernet interface la2 and the microcontroller la3 via an AC-DC converter not shown. The AC power supply la3 is further connected to the Ethernet connection 2 via a power connection 2a3 and an isolation means 2a31, 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.

[0046] The isolation means 2a21 and 2a31 are in particular of the inductive type, for example an isolation transformer.

[0047] 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 1a3 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).

[0048] 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.

[0049] The proposed power supply is a power supply on a pair of twisted connectors, superimposed on the voltage variations generated by the data transmission.

[0050] Each supervision card 1b comprises a data processing stage and a power supply stage lb3.

[0051] 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 lbl9 is designed to separate the voltage variations linked to the data from the voltage variations linked to the AC power supply. la3 and only allows data-related voltage variations to pass through. The isolation means 2b21 is in particular of the inductive type, for example an isolation transformer.

[0052] 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 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 asynchronicity.

[0053] Each cell supervisor lb22 carries out the supervision of a plurality of battery cells 11.

[0054] 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 of a supervision card.

[0055] 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.

[0056] 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).

[0057] 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.

[0058] In a second embodiment of a data processing stage, illustrated by the 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 cells are provided with lb23 galvanic isolation at their connection to the SPI data bus. Galvanic isolation of the first cell supervisor can be omitted since it is powered by the same power supply as the lb21 data buffer and the lb20 Ethernet interface. Any fault affecting the Ethernet interface and the data buffer would also affect its ability to communicate.

[0059] 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.

[0060] 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.

[0061] In a second embodiment of the CMS cell supervision system illustrated by the figure [Fig.6], the isolation means 2a21 and 2a31 are connected respectively to the AC power supply la3 and to the Ethernet interface la2 of the zone controller la by a first winding, as in the first embodiment. The second winding of the isolation means 2a31 and the second winding of the isolation means 2a21 are connected to the Ethernet connection 2 and coupled to each other by a link 4a.

[0062] 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.

[0063] 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.

[0064] Compared to the first embodiment of the CMS cell supervision system, the grouping of the isolation means within a single 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 (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 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 alternative 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) via an isolation means (2b21) and a high-pass filter (1b 19) designed so as to allow only the voltage variations linked to the data to pass through the Ethernet interface (lb20) while rejecting the voltage variations linked to the AC power supply (1 a3), the data processing stage also comprising at least two cell supervisors (lb22) each designed so as 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 a power supply to each cell supervisor (lb22) and to the Ethernet interface (lb20) of the data processing card (1b). supervision (1b) from the power supplied by the alternating current supply (la3), f. the alternating current supply (la3) being designed so that the 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 (1b 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. Supervisory system according to any one of claims 1 to 6, wherein 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 (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) each being connected to their nearest neighbor by a second point-to-point connection, so that the data transmitted by a cell supervisor (lb22) pass 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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