Electronic circuit arranged to connect vehicle battery cells to a monitoring circuit for said cells

Abstract

One aspect of the invention relates to an electronic circuit 1 arranged to electrically connect a plurality of cells 21, 22 of a battery 3 to a cell monitoring circuit 4, said circuit 1 comprising, for each cell 21, 22, a first conductive track 6 arranged to be connected to a positive terminal 2+ and to the cell monitoring circuit 4, and for all the cells 21, 22, a second conductive track 12 arranged to be connected to the negative terminals 2- of said cells 21, 22 and to the cell monitoring circuit 4; Each first conductive track 6 comprises a first transistor 7 connected to a current regulation loop 8 arranged to, when the input current of the first transistor 7 is greater than a first reference value, limit an output current of said first transistor 7. Figure for the abstract: Figure 1

Description

Title of the invention: ELECTRONIC CIRCUIT ARRANGED FOR CONNECTING VEHICLE BATTERY CELLS TO A CIRCUIT SUPERVISION OF SAID CELLS TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to an electronic circuit arranged to electrically connect a plurality of traction battery cells to a cell monitoring circuit of a battery management system. The invention finds a particularly interesting, but not exclusive, application in the field of vehicles equipped with a traction battery having a voltage of at least 48V. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Traction batteries consist of electrochemical cells that can be connected in series or parallel to obtain the voltage and current necessary for the proper functioning of the devices on board the motor vehicle. In order to protect them against any deterioration, extend their lifespan, and maintain them in a state such that they can meet the energy demands of the various on-board applications, the batteries must be managed optimally.

[0003] To this end, this type of battery is usually associated with a battery management system, called BMS (for "Battery Management System" in English).

[0004] More specifically, the battery management system includes at least one cell supervision circuit, called CSC (for "Cell Supervisory Circuit" in English), whose function is in particular to measure the voltage across the cells, the temperature of the cells or to determine the state of charge of the battery, better known by the designation SoC (for "State of Charge" in English).

[0005] Such a cell monitoring circuit is permanently connected to the terminals of each cell of the battery using a low voltage signal connector soldered to a printed circuit board, called a PCB (for "Printed Circuit Board" in English) which is part of the traction battery.

[0006] This low-voltage signal connector has a large number of pins for connection to this printed circuit board. To avoid the risk of a short-circuit current exceeding 20 kA in a high-voltage traction battery, the printed circuit board has significantly increased isolation distances between the electrical traces compared to the existing standard; these isolation distances can, for example, be on the order of 1.5 mm. This increase consequently generates an increase in the dimensions of the low voltage signal connector. Summary of the invention

[0007] The invention offers a solution to the problem mentioned above, by proposing an electronic circuit that allows the isolation distances between the electrical tracks of the printed circuit board to be reduced.

[0008] In this context, the invention thus relates, in its broadest sense, to an electronic circuit arranged to electrically connect a plurality of cells of a traction battery to a cell monitoring circuit of a battery management system, the electronic circuit comprising, • For each cell, a first conductive track arranged to be connected at one end to a positive terminal of the cell and arranged to be connected at a second end to the cell monitoring circuit; and • For all the cells, a second conductive track arranged to be connected at one end to the negative terminals of the cells and arranged to be connected at the other end to the cell monitoring circuit; the electronic circuit being notable in that: • Each first conductive track contains a first field-effect transistor; • Each first field-effect transistor is connected to a current-regulating loop, each current-regulating loop being arranged so that, when the input current of the first field-effect transistor to which said current-regulating loop is connected is greater than a first reference value, it limits the output current of said first field-effect transistor.

[0009] Thus, by limiting the output current of an insulated-gate field-effect transistor connected to a positive terminal for each cell using a current-regulating loop, the cell monitoring circuit is protected against overcurrents. The overcurrent protection provided by the arrangement of this electronic circuit allows the conductive tracks to be placed closer together. Therefore, thanks to the invention, the conductive tracks can be spaced less than 0.5 mm apart. Consequently, the dimensions of the low-voltage connector between the conductive tracks and the cell monitoring circuit can be reduced.

[0010] In addition to the characteristics just mentioned in the preceding paragraph, the electronic circuit according to this aspect of the invention may have one or more additional characteristics from the following, considered individually or according to all technically possible combinations.

[0011] According to a non-limiting embodiment of the invention, each current regulation loop is also arranged so that, when the input current of the first field-effect transistor to which said current regulation loop is connected is less than a second reference value, it stops limiting the output current of said first field-effect transistor. Thus, the output voltage of the first field-effect transistor is substantially the same as the input voltage of said first field-effect transistor.

[0012] According to a non-limiting implementation of the invention, each first field-effect transistor is connected to a second field-effect transistor, each second field-effect transistor being arranged so that, when the input current of the first field-effect transistor to which the second field-effect transistor is connected is greater than a third reference value greater than the first and second reference values, it drives the temporary opening of the first field-effect transistor to which the second field-effect transistor is connected.

[0013] According to a non-limiting implementation of the invention, each second field-effect transistor is also arranged to, when the input current of the first field-effect transistor to which the second field-effect transistor is connected is less than a fourth reference value, drive the closure of the first field-effect transistor.

[0014] According to a non-limiting embodiment of the invention, each second field-effect transistor comprises: • A first end connected to a first field-effect transistor of a first conductive track; and • A second end connected to the second conductive track.

[0015] According to a non-limiting embodiment of the invention, • A first, second field-effect transistor comprises: • A first end connected to a first field-effect transistor of a first conductive track; and • A second end connected to the second conductive track; • Each other second field-effect transistor comprises: • A first end connected to another first field-effect transistor on another first conductive track; and • A second end connected between the first end and the first field-effect transistor of the first conductive track.

[0016] According to a non-limiting implementation of the invention, each first field-effect transistor is of the p-channel type.

[0017] According to a non-limiting implementation of the invention, each current regulation loop comprises a first resistor connected in series with a first field-effect transistor and a bipolar transistor connected in parallel with said first field-effect transistor and a second resistor connected in parallel with said first field-effect transistor and said bipolar transistor.

[0018] According to a non-limiting implementation of the invention, each second field-effect transistor is of the n-channel type.

[0019] According to a non-limiting implementation of the invention, • The first second field-effect transistor is of the n-channel type; and • Each other second field-effect transistor is of the p-channel type.

[0020] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0021] The figures are presented for illustrative purposes only and are in no way limiting of the invention.

[0022] [Fig. 1] shows a first non-limiting example of an embodiment of an electronic circuit according to the invention.

[0023] [Fig.2] shows a second, non-limiting example of an embodiment of a circuit electronic according to the invention. DETAILED DESCRIPTION

[0024] Fig. 1 shows a first non-limiting example of an electronic circuit 1 according to the invention.

[0025] The electronic circuit 1 is arranged to electrically connect a plurality of cells 2b 22 of a traction battery 3 to a cell supervisory circuit 4, referred to as CSC (for "Cell Supervisory Circuit"), of a battery management system 5, referred to as BMS (for "Battery Management System"). According to this embodiment, the cells 2b 22 are connected in series.

[0026] The electronic circuit 1 comprises, for each cell 2b 22, a first conductive track 6 connected: • At one end, at a positive terminal 2+ of cell 2b 22; and • At a second end to the cell monitoring circuit 4.

[0027] It should be noted that each first conductive track 6 includes a first field-effect transistor 7.

[0028] In this non-limiting embodiment example, each first field-effect transistor 7 is an insulated-gate field-effect transistor 7, more commonly referred to as MOSFET (English acronym for "metal-oxide-semiconductor field-effect transistor"). This insulated-gate field-effect transistor 7 can be of the p-channel type.

[0029] Each first field-effect transistor 7 is connected to a current-regulating loop 8.

[0030] Each current regulation loop 8 is arranged so that, when the input current of the first field-effect transistor 7 to which the current regulation loop 8 is connected is greater than a first reference value, it limits the current through the first field-effect transistor 7.

[0031] Each current regulation loop 8 is also arranged so that, when the input current of the first field-effect transistor 7 to which the current regulation loop 8 is connected is less than a second reference value, the current limiting stops so as to allow an output voltage of the first field-effect transistor 7 substantially identical to the input voltage of the first field-effect transistor 7.

[0032] The output voltage being substantially identical to the input voltage of the first field-effect transistor 7 means that the input and output voltages are identical up to a difference in resistance generated by the first field-effect transistor 7 itself.

[0033] The first and second reference values ​​may be identical or different.

[0034] In other words, the first field-effect transistors 7 and the current regulation loops 8 are arranged to protect the cell monitoring circuit 4 against an overcurrent generated by at least one of the cells 2b 22.

[0035] According to this non-limiting embodiment example, each current regulation loop 8 comprises a first resistor 9 connected in series with a first field-effect transistor 7, a bipolar transistor 10 connected in parallel with said first field-effect transistor 7 and a second resistor 11 connected in parallel with said first field-effect transistor 7 and said bipolar transistor 10.

[0036] The sizing of the first resistor 9 and the second resistor 11 is carried out so that a greater voltage drop across the terminals of the first resistor 9 occurs when the current increases, which triggers the conduction of the bipolar transistor 10 and thus the control of the first field-effect transistor 7 is modified, it is no longer saturated and its current is limited.

[0037] In addition, the electronic circuit 1 includes for all the cells 2b 22, a second conductive track 12 arranged to be connected at one end to the negative terminals 2- of the cells and arranged to be connected at a second end to the cell supervision circuit 4.

[0038] According to this non-limiting embodiment example, each first field-effect transistor 7 is connected to a second field-effect transistor 13 connected to a third resistor 14 connected in series with said second field-effect transistor 13.

[0039] Each second field-effect transistor 13 is arranged so that, when the input current of the first field-effect transistor 7 to which the second field-effect transistor 13 is connected is greater than a third reference value greater than the first and second reference values, it drives the temporary opening of the first field-effect transistor 7 to which the second field-effect transistor 13 is connected.

[0040] In addition, each second field-effect transistor 13 is also arranged to, when the input current of the first field-effect transistor 7 to which the second field-effect transistor 13 is connected is less than a fourth reference value, drive the closure of the first field-effect transistor 7.

[0041] The third and fourth reference values ​​may be identical or different.

[0042] According to this embodiment, each second field-effect transistor 13 comprises: • A first end connected to a first field-effect transistor 7 of a first conductive track 6; and • A second end connected to the second conductive track 12.

[0043] According to a non-limiting embodiment example, each second field-effect transistor 13 can be driven by a microcontroller 15.

[0044] Each second field-effect transistor 13 can be of the n-channel type.

[0045] In other words, the first field-effect transistors 7 associated with the second Field-effect transistors 13 are arranged to electrically isolate the cell 4 monitoring circuit from cells 2b 22 when a short-circuit current is present on one of the first conductive tracks 6 and to reconnect the cell 4 monitoring circuit to cells 2b 22 when this short-circuit current is no longer present.

[0046] Fig. 2 shows a second, non-limiting example of an electronic circuit 1 according to the invention.

[0047] As illustrated in [Fig. 1], the electronic circuit 1 comprises, for each cell 2i, 22, a first conductive track 6 connected: • At one end, at a positive terminal 2+ of cell 2b 22; and • At a second end to the cell monitoring circuit 4.

[0048] Each first conductive track 6 is provided with a first field-effect transistor 7, for example of the p-channel type.

[0049] Each first field-effect transistor 7 is connected to a current-regulating loop 8.

[0050] Each current regulation loop 8 is arranged to, • When the input voltage of the first field-effect transistor 7 to which the current-regulating loop 8 is connected exceeds a first reference value, limit the output current of said first field-effect transistor 7; and • When the input voltage of the first field-effect transistor 7 to which the voltage regulation loop 8 is connected is less than a second reference value, stop the current limiting so as to allow an output voltage of the first field-effect transistor 7 substantially identical to the input voltage of the first field-effect transistor 7.

[0051] The first and second reference values ​​may be identical or different.

[0052] According to this non-limiting embodiment example, each current regulation loop 8 comprises a first resistor 9 connected in series with a first field-effect transistor 7, a bipolar transistor 10 connected in parallel with said first field-effect transistor 7 and a second resistor 11 connected in parallel with said first field-effect transistor 7 and said bipolar transistor 10.

[0053] According to this non-limiting embodiment example, each first field-effect transistor 7 is connected to a second field-effect transistor 13 connected to a third resistor 14 connected in series with said second field-effect transistor 13.

[0054] Each second field-effect transistor 13 is arranged so that, when the input voltage of the first field-effect transistor 7 to which the second field-effect transistor 13 is connected is: • Greater than a third reference value greater than the first and second reference values, control the temporary opening of the first field-effect transistor 7 to which said second field-effect transistor 13 is connected; • Less than a fourth reference value, control the closing of the first field-effect transistor 7.

[0055] The third and fourth reference values ​​may be identical or different.

[0056] In a different way from the embodiment illustrated in [Fig. 1], • A first second field-effect transistor 13 comprises: • A first end connected to a first field-effect transistor 7 of a first conductive track 6; and • A second end connected to the second conductive track 12; • The other second field-effect transistor 13 comprises: • A first end connected to another first field-effect transistor 7 of another first conductive track 6; and • A second end connected between the first end and the first field-effect transistor 7 of the first conductive track 6.

[0057] According to this non-limiting embodiment example, the first second field-effect transistor 13 is of the n-channel type and the other second field-effect transistor 13 is of the p-channel type.

[0058] The various aspects of the aforementioned invention offer numerous advantages. Among these, we can mention: • To protect, in case of overcurrent, electrically a cell monitoring circuit of the cells of a traction battery; • Electrically isolate, in case of malfunction, a cell monitoring circuit from the cells of a traction battery; • Electrically reconnect the traction battery cells to the cell monitoring circuit when the malfunction is no longer present; • Tighten the conductive tracks of the electronic circuit so as to reduce the dimensions of the low voltage connector between the conductive tracks and the cell monitoring circuit.

Claims

Demands

1. Electronic circuit (1) arranged to electrically connect a plurality of cells (2b 22) of a traction battery (3) to a cell monitoring circuit (4) of a battery management system (5), said electronic circuit (1) comprising, - for each cell (2b 22), a first conductive track (6) arranged to be connected at a first end to a positive terminal (2+) of said cell (2b 22) and arranged to be connected at a second end to said cell monitoring circuit (4), and - for all the cells (2b 22), a second conductive track (12) arranged to be connected at a first end to the negative terminals (2-) of said cells (2i, 22) and arranged to be connected at a second end to said cell monitoring circuit (4);said electronic circuit (1) being characterized in that: - each first conductive track (6) comprises a first field-effect transistor (7); - each first field-effect transistor (7) is connected to a current regulation loop (8), each current regulation loop (8) being arranged so as, when the input current of the first field-effect transistor (7) to which said current regulation loop (8) is connected is greater than a first reference value, to limit the output current of said first field-effect transistor (7).

2. Electronic circuit (1) according to the preceding claim, characterized in that each current regulation loop (8) is also arranged to, when the input current of the first field-effect transistor (7) to which said current regulation loop (8) is connected is less than a second reference value, stop an output current limitation of said first field-effect transistor (7).

3. Electronic circuit (1) according to any one of the preceding claims, characterized in that each first effect transistor field (7) is connected to a second field-effect transistor (13), each second field-effect transistor (13) being arranged to, when the input current of the first field-effect transistor (7) to which said second field-effect transistor (13) is connected is greater than a third reference value greater than the first and second reference values, drive the temporary opening of said first field-effect transistor (7) to which said second field-effect transistor (13) is connected.

4. Electronic circuit (1) according to the preceding claim, characterized in that each second field-effect transistor (13) is also arranged to, when the input current of the first field-effect transistor (7) to which said second field-effect transistor (13) is connected is less than a fourth reference value, drive the closing of said first field-effect transistor (7).

5. Electronic circuit (1) according to any one of claims 3 to 4, characterized in that each second field-effect transistor (13) comprises: - a first end connected to a first field-effect transistor (7) of a first conductive track (6); and - a second end connected to the second conductive track (12).

6. Electronic circuit (1) according to any one of claims 3 to 4, characterized in that: - a first second field-effect transistor (13) comprises: • a first end connected to a first first field-effect transistor (7) of a first first conductive track (6); and • a second end connected to the second conductive track (12); - each other second field-effect transistor (13) comprises: • a first end connected to another first field-effect transistor (7) of another first conductive track (6); and • a second end connected between the first end and the first field-effect transistor (7) of the first conductive track (6).

7. Electronic circuit (1) according to any one of the preceding claims, characterized in that each first field-effect transistor (7) is of the p-channel type.

8. Electronic circuit (1) according to any one of the preceding claims, characterized in that each current regulation loop (8) comprises a first resistor (9) connected in series with a first field-effect transistor (7), a bipolar transistor (10) connected in parallel with said first field-effect transistor (7) and a second resistor (11) connected in parallel with said first field-effect transistor (7) and said bipolar transistor (10).

9. Electronic circuit (1) according to any one of claims 3 to 5, characterized in that each second field-effect transistor (13) is of the n-channel type.

10. Electronic circuit (1) according to claim 6 characterized in that: - the first second field-effect transistor (13) is of the n-channel type; and - each other second field-effect transistor (13) is of the p-channel type.