System for protecting a battery and battery

Abstract

The present invention relates to a system (14) for protecting a battery (10), the battery (10) including a plurality of modules (12) connected in parallel, the protection system (10) comprising: - a first disconnection device (28), the first disconnection device (28) comprising a contactor (32) having an open position in which the battery (10) is disconnected from all the modules (10); - a second disconnection device (30), the second disconnection device (30) being separate from the first disconnection device (28), the second disconnection device (30) including a cut-off member (40) specific to each module (12), each cut-off member (40) having an open position in which the module (12) is disconnected from the other modules (12) and from the battery (10).

Description

[0001] Battery protection system and battery

[0002] The present invention relates to a battery protection system and a battery comprising such a protection system.

[0003] Typically, a battery comprises one or more current storage cells, also called electrochemical cells or elements. A battery is an electricity-producing device in which chemical energy is converted into electrical energy. The chemical energy comes from electrochemically active compounds deposited on at least one side of electrodes arranged within the battery. The electrical energy is produced by electrochemical reactions during the battery's discharge. The electrodes, arranged in a container, are electrically connected to current output terminals that ensure electrical continuity between the electrodes and the electrical load to which the battery is connected.

[0004] To increase the electrical power output, several sealed accumulators can be connected together to form a battery. A battery can thus be divided into modules, each module consisting of one or more accumulators connected in series and / or parallel. For example, a battery can have one or more parallel branches of accumulators connected in series and / or one or more parallel branches of modules connected in series.

[0005] A charging circuit is usually provided to which the battery can be connected to recharge the cells.

[0006] In addition, an electronic management system including measurement sensors and an electronic control circuit, more or less sophisticated depending on the applications, can be associated with the battery.

[0007] Such a system makes it possible in particular to organize and control the charging and discharging of the battery, in order to balance the charging and discharging of the different accumulators of the battery with respect to each other.

[0008] In the event of a battery malfunction, the management system also isolates the battery to prevent thermal runaway effects that could lead to a battery explosion.

[0009] To do this, the management system controls the opening and closing of a contactor positioned between the battery cells and the battery terminals.

[0010] However, this poses a safety problem because the contactor only opens if the management system commands it to do so. In particular, a failure of the management system can lead to thermal runaway. Therefore, there is a need for a protection system to safeguard the battery with enhanced safety.

[0011] For this purpose, the description relates to a battery protection system, the battery comprising a plurality of modules connected in parallel, the protection system comprising:

[0012] - a first disconnection device, the first disconnection device comprising a contactor having an open position in which the battery is disconnected from all the modules,

[0013] - a second disconnection device, the second disconnection device being separate from the first disconnection device, the second disconnection device having a cutting element specific to each module, each cutting element having an open position in which the module is disconnected from the other modules and the battery.

[0014] Depending on other advantageous aspects, the protection system includes one or more of the following characteristics, taken individually or in all technically possible combinations: - each cutting element is capable of passing irreversibly from a closed position to an open position.

[0015] - each switching device is a pyrotechnic switch.

[0016] - the first disconnection device includes a controller specific to controlling the position of the contactor.

[0017] - the protection system also includes a set of battery-specific sensors, with the controller controlling the position of the contactor based on measurements from the battery-specific sensor set.

[0018] - the second disconnection device includes a control unit specifically designed to control the position of each disconnecting element.

[0019] - for each switching device, the control unit is specific to controlling only the transition from the closed position to the open position.

[0020] - the protection system also includes a set of sensors specific to each module, the control unit controlling the position of each cutting element according to measurements from the set of sensors specific to each module.

[0021] - the control unit is also capable of controlling the position of the contactor.

[0022] - the control unit is designed to control only the transition from the closed position of the contactor to the open position of the contactor.

[0023] - The control unit is a set of logic components. The description also covers a battery including a protection system as previously described.

[0024] The description also relates to a vehicle with a battery as previously described, the vehicle being chosen from the list consisting of an aircraft, a means of rail transport, a means of road transport, a means of maritime or river transport.

[0025] In this description, the expression "specific to" means interchangeably "suited for", "adapted to" or "configured for".

[0026] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0027] - Figure 1 is a schematic representation of a battery equipped with a protection system, and

[0028] - Figure 2 is a schematic representation of the protection system of Figure 1.

[0029] A battery 10 is shown in Figure 1.

[0030] As is known in itself, a battery comprises a plurality of modules 12 and a protection system 14.

[0031] Without being exhaustive, three modules 12 are represented in Figure 1.

[0032] Each module 12 can contain one or more electrochemical elements in a series, parallel or more complex arrangement.

[0033] As explained previously, an electrochemical element is an electricity-producing device in which chemical energy is converted into electrical energy.

[0034] Each electrochemical element therefore delivers a current and a voltage between two terminals.

[0035] Due to the arrangement of the electrochemical element(s), module 12 is thus configured to deliver a current and a voltage between a first terminal 16 and a second terminal 18.

[0036] The first terminals 16 are connected to a terminal 22 of battery 10 while the second terminals are connected to another terminal 20 of battery 10.

[0037] The 12 modules are thus connected in parallel.

[0038] Each module 12 is, in addition, equipped with a first set of 24 sensors.

[0039] The first set 24 is a local set in the sense that it is specific to a module 12. For example, the sensors in the first set 24 are a temperature sensor of the module 12, a voltage sensor between the first terminal 16 and the second terminal 18 and a sensor of the electric current delivered by the module 12.

[0040] Battery 10 also includes a second set of 26 sensors.

[0041] The second set 26 is a global set in the sense that it is specific to the behavior of the entire battery 10.

[0042] For example, the sensors in the second set 26 are a temperature sensor for battery 10, a voltage sensor between the two terminals 20 and 22 of battery 10, and a sensor for the electrical current delivered by battery 10.

[0043] The second set 26 is therefore distinct from the first set 24.

[0044] As a specific example, battery 10 is an on-board power supply in a vehicle.

[0045] According to one embodiment, the vehicle is chosen from the list consisting of an aircraft, a means of rail transport, a means of road transport, a means of maritime or river transport.

[0046] The protection system 14 is interposed between the terminals 20 and 22 of the battery 10 and the modules 12.

[0047] The protection system 14 is designed to protect the battery 10, that is to say to secure it, in the presence of abnormal behavior of one or more of the modules 12.

[0048] In particular, the protection system 14 protects the battery 10 against overcharging, over-discharging, over-temperature and over-current.

[0049] The elements of the protection system 14 are visible more precisely in figure 2.

[0050] The protection system 14 includes a first disconnection device 28 and a second disconnection device 30.

[0051] The first disconnection device 28 includes a contactor 32 and a controller 34.

[0052] The contactor 32 is a controlled electronic component used to open or close a connection between two elements.

[0053] The contactor 32 thus has an open position and a closed position.

[0054] The contactor 32 is positioned between the second disconnecting device 30 and a terminal 20 or 22 of the battery 10.

[0055] In the open position, no current is delivered from the battery 10 output.

[0056] For example, contactor 32 is a solid-state contactor. A solid-state contactor is more often designated by the abbreviation SSR, which refers to the corresponding English term "solid-state relay," generally translated as contactor or static relay.

[0057] Such a contactor is a circuit that allows a connection between two elements to be opened or closed without the use of a mechanical or electromechanical element.

[0058] The contactor 32 is here made up of one or more transistors.

[0059] Here, the contactor 32 includes two transistors mounted back-to-back.

[0060] In addition, each transistor is an insulated-gate field-effect transistor.

[0061] Such a transistor is more often called a MOSFET transistor.

[0062] The acronym MOSFET refers to the English name "metal-oxide-semiconductor field-effect transistor," which can be literally translated as "metal-oxide-semiconductor field-effect transistor."

[0063] In more elaborate variants, the first disconnection device 28 includes several contactors.

[0064] The controller 34 is designed to control the position of the contactor 32.

[0065] For this purpose, the controller 34 sends a control law towards the contactor 32, schematically represented by an arrow 36 in dotted lines on figure 2.

[0066] The controller 34 determines the control law based on the measurements taken by the second set 26 of sensors (the one which relates to the battery 10 as a whole).

[0067] This means that the controller 34 obtains the measurement values ​​from the second set 26. This is schematically represented by three solid arrows 38 in Figure 2. This number of three was chosen to illustrate the frequent case where the three measurements are temperature, voltage and current.

[0068] As a simple illustration, the control law can correspond to a threshold, namely that when the value of a quantity exceeds a threshold, the switch to the open position is imposed on the contactor 32.

[0069] In the example described, the control law is reversible in the sense that if the condition is no longer met, the contactor 32 returns to the closed position.

[0070] Controller 34 is an intelligent system here in the sense that controller 34 includes a processor.

[0071] For example, controller 34 is a microcontroller, the processor then being a microprocessor.

[0072] The second disconnecting device 30 comprises a switching element 40 for each module and a control unit 42. Each switching element 40 is thus connected at one end to a terminal of the contactor 32 and at the other end to the first terminal 16 of the module 12.

[0073] The 40 cutting elements are thus arranged in parallel.

[0074] According to the example in Figure 2, each switching element 40 is a pyrotechnic switch.

[0075] A pyrotechnic switch is a switch that operates in two positions, an open position and a closed position.

[0076] In the open position, the associated module 12 is no longer connected to the contactor 32.

[0077] The pyrotechnic switch is irreversible, meaning it can only switch from the closed to the open position. This opening is achieved by breaking the conductive material using a pyrotechnic device.

[0078] With reference to the corresponding English name, such a 40 switching device is often referred to as a pyro-switch.

[0079] The control unit 42 is a set of discrete logic and electronic components.

[0080] The aim is to limit the number of failures that can occur in control unit 42.

[0081] Alternatively, the control unit 42 is implemented as a programmable logic component, such as an FPGA (Field Programmable Gate Array).

[0082] The control unit 42 is designed to control the position of each of the cutting elements 40.

[0083] This control is shown by arrows 44.

[0084] In the described embodiment, the shut-off elements 40 irreversibly transition from the closed position to the open position. The control of the control unit 42 is therefore limited solely to controlling the opening of each shut-off element 40, that is, the transition of each shut-off element 40 from the closed position to the open position.

[0085] The control can be individualized, so that only one of the 40 cutting elements can change position while the others remain in the same position.

[0086] This makes it possible, in particular, to isolate a faulty module 12 from other modules 12 that are still functional.

[0087] The control unit 42 is thus configured to provide local control.

[0088] To determine the appropriate position of the cutting element 40, the control unit 40 relies on measurements from the first set 24 of each module 12. This is schematically represented in Figure 2 by the three arrows 46, each corresponding to data from a respective first set 24.

[0089] The control unit 42 is also capable of controlling the movement of the contactor 32 to the open position.

[0090] This control is schematically illustrated by arrow 48.

[0091] The control unit 32 operates independently of the controller 34 of the first disconnection device 28.

[0092] This means that the contactor 32 of the first disconnecting device 28 can be closed only if the control unit 42 does not request its opening and if the controller 34 requests its closing.

[0093] The control of the control unit 42 is therefore a redundant control in relation to that already carried out by the controller 34, so that it provides additional security to the protection system 14.

[0094] This safety is reinforced by the fact that the control unit 42 has an irreversible operation, whether for the cutting elements 40 or for the contactor 32.

[0095] This irreversible operation means that the control unit 42 only controls the opening of the cutting elements 40 and the contactor 32.

[0096] The protection system just described thus provides good safety for battery 10, in particular thanks to the independence of the two disconnection devices 28 and 30.

[0097] This independence has two aspects.

[0098] According to one aspect, the state of the first disconnecting device 28 (contactor 32 in open or closed position) and the state of the second disconnecting device 30 (switching elements 40 in open or closed position) are primarily controlled by a separate entity (the control unit 34 for the former and the controller 42 for the latter). The states of the two disconnecting devices 28 and 30 can therefore differ.

[0099] According to a second aspect, the first disconnection device 28 and the second disconnection device 30 operate independently, that is to say, it is sufficient for one of the two disconnection systems 28 and 30 to be in a disconnected state for the battery 10 to be disconnected.

[0100] In this case, this aspect is reinforced by the fact that the first disconnection device 28 and the second disconnection device 30 are connected in series.

[0101] In fact, the two disconnect devices 28 and 30 are connected in series in such a way that the current flowing from the modules 12 to the terminals 20 and 22 of the battery 10 can be interrupted independently by either of the disconnect devices.

[0102] 28 or 30.

[0103] The protection system 14 allows the connection and disconnection of the battery 10 to be managed during operational phases, but also to protect the battery 10 and more particularly the modules 12 from internal short circuits, overcharges, overdischarges, over-temperatures and over-currents.

[0104] The protection system 14 achieves a high level of safety by providing good reliability and a low failure rate. Reliability is further enhanced by the presence of two control units built using different technologies.

[0105] The protection system 14 also makes it possible to do without fuses since each disconnection device 28 or 30 performs its own current measurement and can interrupt the current flow redundantly.

[0106] Other embodiments of the protection system 14 are conceivable.

[0107] According to a first example, controller 34 is the computer for the battery management system 10.

[0108] Such a management system is more often referred to as BMS, the abbreviation referring to the corresponding English term "Battery Management System".

[0109] In such a case, the first disconnection device 28 is part of the management system.

[0110] As an alternative or in addition, the contactor 32 can be made using a different technology.

[0111] Similarly, each cutting element 40 can be replaced by a cutting element of a reversible nature.

[0112] For example, each switching device 40 can be an SSR contactor or an electromechanical contactor.

[0113] The protection system 14 can also include additional components to add features or enhance the level of security it provides.

Claims

DEMANDS 1. Protection system (14) for a battery (10), the battery (10) comprising a plurality of modules (12) connected in parallel, the protection system (10) comprising: - a first disconnection device (28), the first disconnection device (28) comprising a contactor (32) having an open position in which the battery (10) is disconnected from all the modules (10) - a second disconnection device (30), the second disconnection device (30) being separate from the first disconnection device (28), the second disconnection device (30) comprising a switching element (40) specific to each module (12), each switching element (40) having an open position in which the module (12) is disconnected from the other modules (12) and from the battery (10).

2. Protection system according to claim 1, wherein each cutting member (40) is adapted to pass irreversibly from a closed position to an open position.

3. Protection system according to claim 2, wherein each breaking element (40) is a pyrotechnic switch.

4. Protection system according to any one of claims 1 to 3, wherein the first disconnecting device (28) includes a controller (34) adapted to control the position of the contactor (32).

5. Protection system according to claim 4, wherein the protection system (14) further comprises a set (26) of sensors specific to the battery (10), the controller (34) controlling the position of the contactor (32) according to measurements of the set of sensors (26) specific to the battery (10).

6. Protection system according to any one of claims 1 to 5, wherein the second disconnecting device (30) comprises a control unit (42) adapted to control the position of each cutting member (40).

7. Protection system according to claim 6, wherein, for each cutting element (40), the control unit (42) is suitable for controlling only the transition from the closed position to the open position.

8. Protection system according to claim 6 or 7, wherein the protection system (14) further comprises a set (24) of sensors specific to each module (12), the control unit (42) controlling the position of each breaking element (40) according to measurements of the set (24) of sensors specific to each module (12).

9. Protection system according to any one of claims 6 to 8, wherein the control unit (42) is also suitable for controlling the position of the contactor (32).

10. Protection system according to claim 9, wherein the control unit (42) is adapted to control only the transition from the closed position of the contactor (32) to the open position of the contactor (32).

11. Protection system according to any one of claims 6 to 10, wherein the control unit (42) is a set of logic components.

12. Battery (10) comprising a protection system (14) according to any one of claims 1 to 11.

13. Vehicle comprising a battery (10) according to claim 12, the vehicle being chosen from the list consisting of an aircraft, a means of rail transport, a means of road transport, a means of maritime or river transport.

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