FR3124321A1 - BATTERY PACK SYSTEM AGAINST THERMAL DISPERSION BETWEEN MODULES, VEHICLE AND A METHOD BASED ON SUCH A SYSTEM - Google Patents

Abstract

The invention relates to a battery block system (S) for a traction battery of at least one motor vehicle, the system (S) comprising battery cell modules (M1, M4, M5, M8, M9, M12, M13) connected together, and a means for evaluating the heating of said modules, characterized in that it comprises at least one means for optimizing battery longevity as a function of the thermal dispersion between said modules. In particular, the longevity optimization means comprises a positioning configuration of at least one module (M8, M9, M12, M13) which performs better in at least one warmer place, and of at least one module (M1, M4, M5) less efficient at at least one colder location. The invention further relates to a vehicle and a method based on such a system. Fig. 3

Description

BATTERY PACK SYSTEM AGAINST THERMAL DISPERSION BETWEEN MODULES, VEHICLE AND A METHOD BASED ON SUCH A SYSTEM

The invention relates to the field of battery pack devices for motor vehicle traction battery. We generally speak of a battery pack (or “ battery pack ” in English). The invention further relates to vehicles comprising such a device and a method for extending the durability of a battery pack.

In this area, prior art battery pack devices include battery cell modules connected together in series, randomly arranged within the pack. The position of the modules is retained throughout the life of the battery.

Unfortunately, the cell modules have a production deviation related to the manufacture of the cells, as well as the process of their assembly in the block. During the stress on the block (loaded or rolling), thermal dispersion is observed between the different modules. This is linked not only to the dispersion between modules but also to the mechanical integration of the block in the vehicle, and to the inertia of the cooling system. Certain particular uses can accentuate more or less the thermal deviation.

Exposure to different temperatures causes the modules to age at different rates from each other. The temperature is a factor of order 1 which plays on the aging of the battery. Consequently, the performance degradations of the modules in terms of capacitance and internal resistance (also called DCR: Direct Current Resistance) will be heterogeneous.

Thus, there are risks that after a certain period of use, a single module carries more stress than the rest and consequently limits the performance of the block prematurely.

A first objective of the present invention is to counteract the effects of the thermal dispersion undergone by the modules of the battery pack.

A second objective is to make the aging more homogeneous between the modules to prolong the durability of the complete block.

To achieve these objectives, the invention proposes a battery block system for a traction battery of at least one motor vehicle, the system comprising battery cell modules connected together, and a means for evaluating the heating of said modules , characterized in that it comprises at least one of
- at least one more efficient module on the basis of at least one performance parameter, positioned in at least one warmer place, and at least one less efficient module positioned in at least one colder place, in particular at the start of its life ;
- A means for determining an overheating history, and coupled with a means for evaluating said performance parameter of the modules, in particular during their lifetime; and or
- depending on the history and the performance, at least one more efficient module replacing a less efficient module, in particular during maintenance.

The particularity of the invention is that the optimization of the longevity achieved is linked to effects counteracting the deterioration linked to thermal dispersion.

Advantageously, the invention makes it possible to make aging more homogeneous between the modules by acting on the distribution of stress throughout the life of the battery. This results in a significant extension of the durability of the complete block.

Furthermore, the invention makes it possible to take advantage of the dispersion of production between the modules, in particular at the start of life (BOL - Beginning Of Life).

It also makes it possible to have more reactivity in the event of thermal dispersion between the modules and thus to optimize the durability of the block, in particular in maintenance.

The positioning of the modules according to the performances and the hot places makes it possible to homogenize the performances of the modules of the block, because the hot places will limit the performances of the most efficient modules.

The evaluation of performance histories and parameters makes it possible to implement a selective and efficient replacement of modules.

Alternatively, the performance parameters of the modules include high capacitance and/or low DC resistance. These parameters give a good objective evaluation of the performance of the modules.

According to a variant, the module heating evaluation means is configured to determine at least one heating parameter being
- a threshold of time spent above a given minimum thermal difference with respect to given minimum and maximum threshold temperatures; and or
- a cumulative energy threshold corresponding to such a thermal difference.

This makes it possible to have an objective assessment of the deterioration of the modules, and to know which module needs to be replaced.

According to a variant, the battery block system comprises a power limitation system of at least one hottest module, while driving and/or under load. This makes it possible to counteract thermal dispersion in a simplified manner by means of a suitable electronic circuit.

Alternatively, the battery pack system includes a cooling system of at least one hottest module. This makes it possible to limit the thermal dispersion in situ.

The invention further relates to a battery pack management method for traction battery of at least one motor vehicle, the battery pack comprising battery cell modules connected together, the method comprising steps for
- evaluate the heating of said modules,
and at least one step among
- positioning at least one more efficient module on the basis of at least one performance parameter, in at least one warmer place, and at least one less efficient module in at least one colder place, in particular at the start of its life;
- determining a temperature history, and evaluating said performance parameter of the modules, in particular in maintenance; and
- depending on history and performance, replace with at least one more efficient module, one less efficient module, in particular during maintenance.

The invention also relates to a computer program product comprising program code instructions for the execution of the steps of the method according to the invention, when said program is running on a computer.

Another object of the invention relates to a motor vehicle comprising a battery block system according to the invention.

The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which:
- schematically illustrates part of a battery pack for a system according to the invention with the modules connected in series;
- schematically illustrates a view in space of a block part of a battery block system comprising battery cell modules according to a preferred embodiment of the invention;
- schematically illustrates details of the modules of the block of the , including thermal dispersion and module replacements; and
- schematically illustrates a plan view of a battery pack system according to the preferred embodiment in a vehicle.

The invention relates to a battery block system S. The battery block system S is particularly suitable for being implemented in a traction battery B of one or more motor vehicles V. This is in particular a lithium ion battery.

The system S comprises battery cell modules which can be illustrated by the figures with in particular the references M, M1, M4, M5, M8, M9, M12, M13. The reference M is used to generically designate the modules.

In the context of the invention, the expression "cell module" can be understood as an assembly of several battery cells connected together to form a module, to be connected to other modules to form a battery pack (in which case the “module of cells” precision can be used); or be heard as a single cell, to be connected to other cells to form a battery pack.

The M cell modules are connected together, preferably in series. Similarly, the cells of a cell module are connected together, preferably in series.

The system S further comprises a means of evaluating the heating E of said modules M. This means E can comprise or be connected to a temperature sensor. Preferably, this means E can be or be part of a computer or processor using temperature data. More specifically, the assessment can be based on simulations, maps and/or real-time temperature measurements.

The battery block system S can be associated with a battery management system BMS grouping together the computers or processors used in the implementation of the battery block system S.

According to the invention, the system S further comprises means making it possible to optimize the longevity of the battery as a function of the thermal dispersion between the said modules M.

Thermal dispersion can be illustrated by the . The modules having undergone high temperatures in descending order are modules M12, M13, M8, M9, M4, M5, M2 M1. We can talk about temperature gradient in this order. In particular, in the figures, the coloring in white corresponds to temperatures ranging from 30 to 36° C.; the coloring in “minus” signs corresponds to temperatures ranging from 36 to 42° C.; the coloring in “plus” signs corresponds to temperatures ranging from 42 to 48°C; the black coloration corresponds to temperatures ranging from 48 to over 50°C.

The particularity of the invention is that the optimization of longevity is linked to effects counteracting deterioration by thermal dispersion.

Advantageously, the means detailed below make it possible to make the aging more homogeneous between the modules M by acting on the distribution of the stress throughout the life of the battery. This results in a significant extension of the durability of the complete block.

Moreover, these means make it possible to take advantage of the dispersion of production between the modules, in particular at the start of life.

They also make it possible to have more reactivity in the event of thermal dispersion between the modules and thus to optimize the durability of the block, in particular in maintenance.

In addition, the invention makes it possible to have a better autonomy of electric vehicles (EV) and plug-in hybrids (PHEV) in an aged state; better performance in terms of available power of hybrid electrified vehicles (PHEV and HEV) by limiting an acceleration of the increase in internal resistance (DCR); extend the durability of the overall block and reduce the stress suffered by the most limiting module and thus avoid a loop effect: greater degradation, greater increase in internal DCR resistance, higher heating, acceleration of degradation.

In particular, the system S comprises at least one module M8, M9, M12, M13 that is more efficient with reference to at least one performance parameter, positioned in at least one warmer place, and at least one module M1, M4, M5 less performer positioned in at least one cooler location. More generally, the positioning can be implemented according to temperature and performance gradients.

Thermal dispersion can be determined at the start of life (or during maintenance) by thermal simulations but could be deduced from the thermal characterizations of a certain number of blocks during development. Preferably, this is done taking into account the integration constraints (Busbar, cooling system, etc.) of the complete block in its integration environment.

An assumption for the simulation may be an absence of output dispersion at a DCR capacitance or resistance scale. Test and/or training data can be used for simulation.

In a variant, the invention can be implemented at the beginning of its life. Thus, the modules are placed in the block so as to arrange one or more most efficient M modules in the location(s) which will have the maximum heating at block level. Similarly, the least efficient modules M are arranged at or at the coolest locations. We can talk about specific positioning of the modules (or "mapping" in English).

Performance can be assessed through objective performance parameters affected by temperature such that high temperature negatively affects performance parameters. In particular, the performance parameters include capacitance and/or DC resistance (or DCR resistance). The higher the capacity, the better the performance, and it is negatively affected by high temperatures. The lower the DCR resistance, the better the performance, and it is negatively affected by high temperatures.

Thus, the simulation or the characterizations can result in a statistical classification of the modules M according to their performances (capacitance and resistance DCR). This classification can be used to guide positioning.

For thermal simulations, several representative profiles of use can be tested.

Based on thermal dispersion, the most efficient M modules will age faster than the others and the degradation would be less on the less efficient modules, which makes it possible to optimize the total degradation of the block.

The BMS battery management system can be equipped with a balancing system to keep the cells in the same level of charge and thus preserve their durability. Preferably, apart from the thermal stress, so that the degradation within the block is homogeneous, it is also necessary to ensure that the modules M remain in a zone of state of charge SOC as close as possible.

The invention can be implemented during use (in particular when driving or under load). In this case, thermal sensors can be used to determine the hottest and coolest places. The sensors are connected to the BMS battery management system. In this case, the evaluation means E is preferably part of the BMS battery management system or is remotely connected to the latter via a cloud computing system (known as “cloud” or “over the air” in English ).

Furthermore, the performance parameters can be evaluated by a corresponding evaluation means P preferably forming part of the battery management system BMS or connected to the latter in the same way as explained previously.

In the preferred variant, the battery pack system is configured to monitor the difference between a maximum temperature Tmax of all modules M and a minimum temperature Tmin of all modules M, respectively representing the hottest and coldest points in the block. The system S can then associate a dedicated reactivity in the event of exceeding a maximum threshold of the given deviation.

For example, if Tmax-Tmin is greater than the threshold, then a reduction in the power limitation can be implemented when driving or charging to further limit the heating of battery B and try to make it more uniform. A power limitation system may be provided. It may be according to the prior art.

Alternatively or in combination, if Tmax-Tmin is greater than the threshold, then a more demanding cooling activation (higher cooling flow rate) or a specific thermal balancing system (controllable if possible) can be implemented. It can be a cooling system of at least one hottest M module.

More generally, responsiveness is achieved with the aim of limiting the time the battery experiences under thermal dispersion conditions.

One can imagine a counter for the time spent above a minimum thermal difference (set at 10°C for example) and/or the cumulative energy in kWh used during this difference: in the event of crossing a relative threshold to the lifetime of the battery or its use, the system S can indicate an alert for an electro/thermal analysis of the module M and/or block.

The thermal dispersion information can be coupled with SOC state of charge deviation information (for example a time spent above a certain SOC state of charge deviation threshold, because the state of charge is a factor that also acts on the aging of the battery.

The invention can be implemented after use (in particular in maintenance). In this case, the thermal sensors and the evaluation means E, P are configured to determine a history of the heating of the modules M and preferably a history of the performances, in particular of the performance parameters. The performance parameters taken into account can include health states of each module, in particular the capacity health state (SOHC), and the DCR resistance health state (SOHR).

The battery block system can then implement a proposed position swapping/reorganization of the M modules within a block to slow down the aging effect due to thermal dispersion. Thus, the modules M are fixed in the block in a removable manner so as to facilitate the repositioning of the modules M. In particular, the welding of the modules M in the block is to be avoided.

To this end, the battery block system S implements monitoring of the history of the heating of the modules M preferably in the management system BMS or by cloud computing with data uploaded by telematics.

In addition, the S system combines this heating information with module performance information, including DCR capacitance and resistance, for better reorganization of M modules in the block.

You can decide to place the M module with the highest DCR resistance in the coolest place.

The frequency of verification of the possibility of switching can be related to the use of the battery. To this end, a minimum number of kWh for discharging the battery can be set; a minimum variation in capacitance or resistance DCR, for example of at least 5%; or set a temporal frequency, for example every 2 to 3 years, to determine the verification frequency.

A thermal dispersion threshold can be calibrated below which it is estimated that thermal dispersion has no significant impact on the degradation of battery performance (example of a block having effective cooling with good thermal homogeneity).

The can illustrate examples of permutations of modules M having undergone significant thermal stresses. Modules M12, M13, M8, M9, M4, M5, M2 are replaced respectively by modules M14, M15, M10, M11, M6, M7, M3. The module M1 which has not undergone any significant stress can be kept in place.

In another embodiment, the classification of the modules can be applied to the scale of a vehicle fleet, for example to target the most efficient M modules for the most stressful applications such as uses in regions or countries. the hottest.

In another embodiment, the system may include or be associated with a per-module cooling system configured to target coolant flow to the hottest module(s).

The invention further relates to a method for battery pack management for traction battery B of at least one motor vehicle V. The battery pack comprises battery cell modules M connected together.

The method comprises all the steps allowing longevity optimization, or at least one action of the battery block system or of one of its elements, including at least one action of at least one means of the system S.

In particular, the method comprises a step for evaluating the heating of said modules M. The evaluation has already been described previously.

More particularly, the method further comprises a step for optimizing the battery longevity as a function of the thermal dispersion between said modules M.

The invention also relates to a computer program product comprising program code instructions for the execution of the steps of the method as described above, when said program is running on a computer.

The program can be loaded into a BMS battery management system as previously described.

The invention also relates to a motor vehicle V comprising a battery block system S as described above.

Claims (8)

Battery block system (S) for traction battery (B) of at least one motor vehicle (V), the system (S) comprising battery cell modules (M, M1, M4, M5, M8, M9 , M12, M13) connected together, and a heating evaluation means (E) of said modules (M, M1, M4, M5, M8, M9, M12, M13), characterized in that it comprises at least one among
- at least one module (M8, M9, M12, M13) more efficient on the basis of at least one performance parameter, positioned in at least one warmer place, and at least one module (M1, M4, M5) less efficient positioned in at least one colder place, especially at the beginning of life;
- a means (E) for determining a heating history, and coupled to a means for evaluating said performance parameter (P) of the modules (M), in particular during life; and or
- depending on history and performance, at least one more efficient module (M3, M6, M7, M10, M11, M14, M15) replacing a less efficient module (M1, M4, M5, M8, M9, M12, M13) , especially in maintenance. Battery pack system (S) according to claim 1, characterized in that the performance parameters (P) of the modules comprise high capacity and/or low DC resistance. Battery pack system (S) according to any one of claims 1 to 2, characterized in that the module overheating evaluation means (E) is configured to determine at least one overheating parameter being
- a threshold of time spent above a given minimum thermal difference with respect to given minimum and maximum threshold temperatures; and or
- a cumulative energy threshold corresponding to such a thermal difference. Battery block system (S) according to any one of Claims 1 to 3, characterized in that it comprises a system for limiting the power of at least one hottest module (M), while driving and/or in charge. Battery block system (S) according to any one of Claims 1 to 4, characterized in that it comprises a cooling system of at least one hottest module (M). Battery pack management method for traction battery (B) of at least one motor vehicle (V), the battery pack comprising battery cell modules (M, M1, M4, M5, M8, M9, M12 , M13) connected together, the method comprising steps for
- evaluate the heating of said modules (M, M1, M4, M5, M8, M9, M12, M13),
and at least one step among
- position at least one module (M8, M9, M12, M13) more efficient on the basis of at least one performance parameter, in at least one warmer place, and at least one module (M1, M4, M5) less performs well in at least one colder location, especially in early life;
- determining a temperature history, and evaluating said performance parameter (P) of the modules (M), in particular during maintenance; and
- depending on history and performance, replace with at least one more efficient module (M3, M6, M7, M10, M11, M14, M15), one less efficient module (M1, M4, M5, M8, M9, M12, M13), especially in maintenance. Computer program product comprising program code instructions for carrying out the steps of the method according to claim 6, when said program is running on a computer. Motor vehicle (V) comprising a battery pack system (S) according to any one of Claims 1 to 5.