Method for managing the temperature of a battery for an automotive vehicle

Abstract

The invention relates to a method for managing the temperature of a traction battery (1) of a motor vehicle (10) comprising a thermal regulation system (3) for the traction battery, the method comprising steps of: measuring a maximum temperature at time t of the traction battery, then comparing it with at least one threshold temperature among a threshold stop temperature "CoolingStopTemperature", a threshold activation temperature "CoolingActivationTemperature", a first threshold temperature "StartDeratingTemperature" and a second threshold temperature "NoPowerTemperature", wherein, prior to the measurement step, it comprises a re-evaluation of at least one threshold temperature based on an instantaneous health status at time t of the traction battery (1) evaluated by a battery management system (2) and a predefined target aging level at that time t. Figure 1

Description

Title of the invention: Method for managing the temperature of a battery for an automobile. Technical field of the invention

[0001] The invention relates, in general, to the technical field of thermal management of traction batteries for an electric or hybrid motor vehicle. In particular, the invention relates to a method for managing the temperature of a traction battery, especially a lithium traction battery, for an electric or hybrid motor vehicle. Prior art

[0002] Today, a traction battery, particularly a lithium battery, used in an electric or hybrid vehicle consists of a set of electrical cells. These electrical cells are assembled in an electrical cell module, and several electrical cell modules are assembled to form the traction battery.

[0003] To ensure thermal management of the traction battery, several components are integrated into the vehicle. Internally, a cooling system is most often implemented within the traction battery: air cooling, refrigerant cooling, or water cooling (with a dedicated water circuit). Some traction batteries rely exclusively on natural convection. Externally, a cooling circuit typically includes a conventional cooling system (with or without a cooler), which can be more or less complex, depending on the components to be cooled inside the vehicle and the cost.

[0004] Furthermore, to ensure thermal management of the traction battery, the maximum power (alternatively, the maximum current) allowed during charging, discharging, or regenerative braking by the traction battery is gradually limited from a first threshold temperature, "TemperatureStartDerating," until it drops to OKW from a second threshold temperature, "TemperatureNoPower," which is higher than the first threshold temperature (see [Fig. 2]). This constitutes a first control function. Most often, these first and second threshold temperatures are set to limit degradation of the traction battery (which is more significant when the traction battery is at a high temperature). These threshold temperatures also protect against safety risks related to high temperatures.

[0005] Furthermore, the cooling system is activated when the traction battery deviates from an optimal operating range according to a second control function as follows. When the maximum temperature T_BatMax of the traction battery exceeds a certain activation threshold temperature "CoolingActivationTemperature", the cooling system can be activated. The cooling system remains activated as long as the maximum temperature T_BatMax has not fallen below a shutdown threshold temperature "CoolingShutdownTemperature" and / or possibly after a predetermined time.

[0006] Most often, these activation (and deactivation) temperatures of the cooling system are constant and fixed once and for all, the activation temperature "CoolingActivationTemperature" being set in such a way as to reduce overconsumption related to the cooling system, and therefore minimize the charging time of the traction battery and allow it to remain within its full performance range. By design, the activation temperature "CoolingActivationTemperature" is therefore close to the first threshold temperature "StartDeratingTemperature" of the traction battery.

[0007] For example, if a traction battery reduces its available power from 45°C (Max battery temperature), the cooling system can advantageously be activated from 40°C.

[0008] The above currently allows for a compromise to be managed to preserve battery durability by applying the two control functions as early as possible (if the cooling system is not sufficiently activated or if the power degradation occurs too late, this results in a rise in the average temperature of the traction battery, leading to its accelerated degradation compared to the expected use of the traction battery), to preserve full battery performance by applying the two control functions as late as possible (the concept of performance includes not only traction performance (including regenerative braking), but also charging performance (which translates into charging time)), and to minimize overconsumption by the motor vehicle by applying cooling as late as possible (if the cooling system is activated too often,This leads to increased electrical consumption (activation of the cooler, cooling pumps, air conditioning compressor, etc.), which can result in a loss of range in the case of electrified vehicles.

[0009] A thermal management system for the traction battery is most often sized and activated to cover the worst use case of electric motor vehicles: high annual mileage, severe climatic conditions. The commitment to sustainability for a user of the electric or hybrid motor vehicle is therefore - most of the time - ensured thanks to these strategies (and the intrinsic characteristics of the traction battery chemistry) for all users, but at the expense of: overconsumption of the motor vehicle to activate the cooling system, a greater occurrence of power degradation and a change in the climatic conditions of use of the motor vehicle (in particular an average ambient temperature).

[0010] While the above is consistent for a "worst-case" user, it becomes far too restrictive for less demanding users who use their electric or hybrid vehicle less frequently, or who live in a milder climate. For these users, the power limitation is too severe, or the consumption in use is too high relative to the optimal need. Description of the invention

[0011] The invention aims to remedy all or part of the drawbacks of the prior art by proposing in particular a solution enabling optimal thermal management of a traction battery of an electric or hybrid motor vehicle, regardless of the type of user of said electric or hybrid motor vehicle.

[0012] To this end, according to a first aspect of the invention, a method for managing the temperature of a traction battery of a motor vehicle is proposed, comprising a battery management system, a thermal regulation system connected to the traction battery, the method comprising the steps of: • Measurement of a maximum temperature at time t of the traction battery, then • Comparison with at least one threshold temperature among a threshold stop temperature "CoolingStopTemperature", a threshold activation temperature "CoolingActivationTemperature", a first threshold temperature "StartDeratingTemperature" and a second threshold temperature "NoPowerTemperature", in which, prior to the maximum temperature measurement step, the process includes a preliminary step of re-evaluation at time t of at least one threshold temperature among the threshold stop temperature "CoolingStopTemperature", the threshold activation temperature "CoolingActivationTemperature", the first threshold temperature "StartDeratingTemperature" and the second threshold temperature "NoPowerTemperature", re-evaluation being a function of an instantaneous health status SOH(BMS) at time t of the traction battery evaluated by the battery management system and a predefined target aging level SOH_Target at that time t.

[0013] According to one embodiment, the target aging level is defined in relation to a mileage traveled and / or a number of years elapsed since the start of the life of the traction battery and / or a number of MWh traveled in the traction battery.

[0014] According to one embodiment, the instantaneous health state and the target aging level are at least one of an energy health state, a European health state as defined by the Euro7 standard, a capacity health state, a power health state and a resistance health state.

[0015] According to one embodiment, the step of re-evaluating the first threshold temperature "TemperatureStartDerating" and the second threshold temperature "TemperatureNoPower" evolve according to an increasing function of the gap between the instantaneous health state and the target aging level.

[0016] According to one embodiment, the step of re-evaluating the threshold stop temperature "CoolingStopTemperature" and the threshold activation temperature "CoolingActivationTemperature" evolve according to an increasing function of the gap between the instantaneous health state and the target aging level.

[0017] According to one embodiment, during the re-evaluation step, the re-evaluation is a function of an instantaneous state of charge of the traction battery estimated by the battery management system.

[0018] According to one embodiment, during the re-evaluation step, the re-evaluation is also a function of the instantaneous state of health of the traction battery, taken alone.

[0019] According to one embodiment, during the re-evaluation step, at least one of the threshold temperatures among the threshold shutdown temperature, the threshold activation temperature, the first threshold temperature and the second threshold temperature is re-evaluated remotely.

[0020] According to another aspect of the invention, a traction battery for a motor vehicle is provided comprising a battery management system, a thermal regulation system connected to the traction battery, in which the battery management system further comprises a computer arranged to implement the method having at least one of the preceding technical characteristics.

[0021] According to yet another aspect of the invention, a motor vehicle is provided comprising a traction battery, a battery management system, a thermal regulation system connected to the traction battery comprising an electric machine, the traction battery having one of the preceding technical characteristics. brief description of the figures

[0022] Other features and advantages of the invention will become apparent from the following description, with reference to the accompanying figures, which illustrate: • [Fig.1]: a schematic view of an electric or hybrid motor vehicle comprising a traction battery and a thermal regulation system for the latter; • [Fig. 2]: a curve illustrating the maximum power available as a function temperature for a traction battery; • [Fig. 3]: A curve illustrating the target health state of a traction battery depending on the time elapsed since the beginning of his life; • [Fig. 4]: a curve illustrating the evolution of different threshold temperatures by implementing an embodiment of a temperature management method for a traction battery according to the invention.

[0023] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED description of a method of implementation

[0024] Figure 1 schematically illustrates an electric or hybrid motor vehicle 10 comprising, in a manner known per se, a powertrain including an electric traction machine. The motor vehicle 10 further comprises a traction battery 1 electrically connected to the electric machine of the powertrain. The traction battery 1 includes a battery management system 2 (also called a BMS, according to the English acronym for "Battery Management System"). The motor vehicle 10 further comprises a thermal circuit 4 connecting a heat exchanger 41 of the traction battery 1 to a thermal control system 3 of the motor vehicle 10. The latter will allow the traction battery 1 to be cooled or heated.

[0025] We will now describe in detail a method for managing the temperature of a traction battery according to the invention which is implemented within the motor vehicle 10 previously described.

[0026] In a manner known per se, the temperature management method for a traction battery according to the invention comprises a step of measuring an instantaneous maximum temperature T_BatMax of the traction battery 1. This measurement is performed by the battery management system 2. Following this measurement of the maximum temperature T_BatMax, the temperature management method for a traction battery according to the invention performs a comparison with the various threshold temperatures, which are, in order, the cutoff temperature "CoolingCutOffTemperature", the activation temperature "CoolingActivationTemperature", the first threshold temperature "StartDeratingTemperature", and the second threshold temperature "NoPowerTemperature". Figure 2 illustrates the order of these threshold temperatures.

[0027] As a reminder, if the maximum temperature T_BatMax measured is lower than the threshold shutdown temperature "TemperatureDArrêtDuCooling", the management process of the temperature of a traction battery according to the invention causes the thermal regulation system 3 to stop if the latter is activated.

[0028] If the maximum temperature T_BatMax measured is greater than the activation threshold temperature "TemperatureDActivationDuCooling", the temperature management method of a traction battery according to the invention activates the thermal regulation system 3 if the latter is not activated.

[0029] If the measured maximum temperature T_BatMax exceeds the first threshold temperature "TemperatureStartDerating", the traction battery temperature management method according to the invention triggers a degradation of the maximum power supplied by the traction battery 1. This degradation increases as the maximum temperature T_BatMax increases. The traction battery temperature management method according to the invention cuts off the power supplied by the traction battery 1 when the maximum temperature T_BatMax becomes greater than or equal to the second threshold temperature "TemperatureNoPower".

[0030] Prior to the step of measuring the instantaneous maximum temperature TbatMax, the temperature management method for a traction battery according to the invention performs a step of re-evaluating at least one of the threshold temperatures among the threshold shutdown temperature "CoolingStopTemperature", the threshold activation temperature "CoolingActivationTemperature", the first threshold temperature "StartDeratingTemperature", and the second threshold temperature "NoPowerTemperature". The re-evaluation is a function of an instantaneous health status SOH(BMS) of the traction battery 1 evaluated by the battery management system 2 and a target aging level SOH_Target at that instant as given by the curve in [Fig. 3]. This curve illustrates the evolution of the aging level SOH_Target of the traction battery 1 over time since the beginning of its life.

[0031] Alternatively, the SOH_Target aging level is defined in a non-limiting manner with respect to a mileage traveled and, optionally, with respect to a number of years elapsed since the beginning of its life (production of the first battery, or delivery of the first vehicle to the user) and / or a number of MWh traveled in the traction battery 1 (optionally within each electrical cell, if a health status is calculated for each electrical cell). This target aging level SOH_Target can be set by taking into account any under-declaration of energy or energy reserve considered during its life.

[0032] In another embodiment, the target aging level SOH_Target of the traction battery 1 is also defined with regard to regulatory or consumer requirements, by representatively interpolating between: 100% at the beginning of life (BOL), a target SOCE level (European state of health as defined by the Euro7 standard) (or any parameter of the same nature) after the number of years (or kilometers traveled, or energy that has passed through traction battery 1) set by the regulations. The target SOCE is the maximum of the following SOCEs: a target SOCE interpolated (linearly or non-linearly) on an age basis of traction battery 1 relative to the regulatory targets at BOL, 5 years, 8 years, etc.; a target SOCE interpolated (linearly or non-linearly) on a virtual kilometer basis (as defined by the Euro 7 standard) of traction battery 1 relative to the regulatory targets at BOL, 5 years, 8 years, etc.; a virtual mileage as defined by the Euro 7 standard (sum of the actual mileage and the stationary cycle time (V2X) converted into equivalent kilometers, according to the definition adopted by the Euro 7 standard).This interpolation is not necessarily linear, in order to take into account the shape of the aging curve whose degradation slope tends to decrease over time (before a sudden failure of traction battery 1).

[0033] Thus, the temperature management method for a traction battery according to the invention allows the traction battery 1 to operate at higher temperatures at full power when the instantaneous state of health (SOH(BMS)) is significantly higher than the target aging level. Specifically, the power degradation activation, or the activation of the thermal regulation system, is applied starting at higher maximum temperatures T_BatMax.

[0034] On the other hand, this preserves the durability of the traction battery 1 when the instantaneous state of health (SOH(BMS)) is significantly lower than the target aging level SOH_Target. Specifically, the power degradation activation, or the activation of the thermal regulation system, is applied starting from lower maximum temperatures T_BatMax.

[0035] The instantaneous health state SOH(BMS) and the aging level SOH_Target are chosen at least one from an energy health state, a European SOCE health state as defined by the Euro7 standard, a capacity health state, a power health state and a resistance health state.

[0036] In an alternative embodiment of the temperature management method of a traction battery according to the invention, the step of re-evaluating the first threshold temperature "TemperatureStartDerating" (from which the maximum power (or current) allowed during charging, discharging or regenerative braking decreases or degrades) and the second threshold temperature "TemperatureNoPower" (from which the maximum power (or current) allowed during charging, discharging or regenerative braking becomes zero) evolve according to an increasing function of the difference between the instantaneous health state SOH(BMS) and the target aging level SOH_Target.

[0037] In another variant of the method for managing the temperature of a traction battery according to the invention, a performance of the thermal regulation system 3 evolves according to a decreasing function of the gap between the instantaneous health status SOH(BMS) and the target aging level SOH_Target.

[0038] In another variant of the traction battery temperature management method according to the invention, the step of re-evaluating the threshold stop temperature "CoolingStopTemperature" and the threshold activation temperature "CoolingActivationTemperature" evolve according to an increasing function of the gap between the instantaneous health state SOH(BMS) and the target aging level SOH_Target.

[0039] In another embodiment of the traction battery temperature management method according to the invention, the re-evaluation step also depends on an instantaneous state of charge (SOC) of the traction battery 1 estimated by the battery management system 2. Thus, the cutoff temperature threshold "CoolingCutOffTemperature" and the activation temperature threshold "CoolingActivationTemperature" are re-evaluated based on the instantaneous state of charge (SOC) at time (t). For example, in the case of a high instantaneous state of charge (SOC), more cooling is required, conversely, in the case of a low instantaneous state of charge (SOC), less cooling is required.For certain battery chemistries (such as NMC - nickel manganese cobalt), the degradation rate being greater at high state of charge, the first threshold temperature "TemperatureStartDerating" can be modulated according to the average state of charge, allowing cooling temperatures to be adapted according to this average state of charge.

[0040] In another embodiment of the traction battery temperature management method according to the invention, the re-evaluation step also depends on the instantaneous state of health (SOH(BMS)) of the traction battery 1, considered alone. The user can choose between less frequent thermal regulation at the beginning of its life as long as the traction battery's health remains sufficiently good, or maintaining a more conservative thermal regulation strategy. In the first case, the user can minimize consumption (in the vehicle or at the charging point) by less systematic activation of the thermal regulation system 3. In the second case, the user benefits from full performance of the traction battery 1 over a wider and longer operating range.

[0041] Fig. 3 illustrates a re-evaluation of the threshold temperatures previously mentioned during the implementation of certain variants of the temperature management process of a traction battery according to the invention previously described.

[0042] In another embodiment of a method for managing the temperature of a traction battery according to the invention, the re-evaluation step is carried out in based on the difference between the average temperature observed by the traction battery 1 over its entire lifespan up to that point, and an average design temperature taken into account to determine the thermal regulation and power degradation strategies. In other words, an implementation of this embodiment of the temperature management process for a traction battery according to the invention aims to adapt the activation conditions for power degradation and thermal regulation of the traction battery 1, based on the difference between the average temperature observed by the traction battery 1 over its entire usage up to time "t" and the average design temperature.Furthermore, according to an alternative embodiment of this method for managing the temperature of a traction battery according to the invention, the activation of the thermal regulation is delayed based on a damage criterion that depends, without limitation, on the average temperature, the average state of charge (SOC), the number of kWh exchanged, the age, etc. This damage criterion is compared to a target damage criterion based solely on age and mileage.

[0043] In yet another embodiment of a method for managing the temperature of a traction battery according to the invention, the step of re-evaluating at least one of the threshold temperatures among the threshold stop temperature "CoolingStopTemperature", the threshold activation temperature "CoolingActivationTemperature", the first threshold temperature "StartDeratingTemperature" and the second threshold temperature "NoPowerTemperature" is carried out remotely.

[0044] It follows from the above that the implementation of the temperature management method of a traction battery according to the invention as previously described makes it possible to adapt the thermal regulation of the traction battery 1 of an electric or hybrid motor vehicle 10, and, consequently, the aging and degradation of said traction battery 1, to the actual conditions of use of the motor vehicle 10.When the actual degradation of the traction battery is lower (respectively higher) than a maximum permissible degradation (with regard to the guaranteed commitment to the user, regulatory requirements, or the state of the art) for a given period of use, the temperature management method of a traction battery according to the invention aims to activate the thermal regulation of the traction battery 1 more quickly by increasing (respectively reducing) the first threshold temperature "TemperatureStartDe rating" of the activation of power degradation and / or the activation threshold temperature "TemperatureDActivationDuCooling" of the thermal regulation system of the traction battery 1. This makes it possible to minimize the consumption of the system. thermal regulation and optimizing charging time (respectively improving durability in relation to the target).

[0045] Naturally, the invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different embodiments of the invention without departing from the scope of the invention.

[0046] It is emphasized that all features, as they are apparent to a person skilled in the art from the present description, drawings and attached claims, even if in practice they have only been described in relation to other specific features, both individually and in any combinations, may be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances make such combinations impossible or meaningless.

Claims

Demands

1. A method for managing the temperature of a traction battery (1) of a motor vehicle (10) comprising a battery management system (2), a thermal regulation system (3) connected to the traction battery, the method comprising the steps of: - Measuring a maximum temperature at time t of the traction battery, then - Comparing it with at least one threshold temperature among a threshold stop temperature "CoolingStopTemperature", a threshold activation temperature "CoolingActivationTemperature", a first threshold temperature "StartDeratingTemperature" and a second threshold temperature "NoPowerTemperature", in which, prior to the step of measuring the maximum temperature, the method comprises a preliminary step of re-evaluating at time t at least one of the threshold temperatures among the threshold stop temperature "CoolingStopTemperature", the threshold activation temperature "CoolingActivationTemperature",the first threshold temperature “TemperatureStartDerating” and the second threshold temperature “TemperatureNoPower”, re-evaluation being a function of an instantaneous health status SOH(BMS) at time t of the traction battery (1) evaluated by the battery management system (2) and a predefined target aging level SOH_Target at that time t.

2. A method according to claim 1, wherein the target aging level is defined in relation to a mileage traveled and / or a number of years elapsed since the start of the traction battery's life and / or a number of MWh traveled in the traction battery.

3. A method according to any one of claims 1 to 2, wherein the instantaneous health state and the target aging level are at least one of an energy health state, a European health state as defined by Euro7, a capacity health state, a power health state and a resistance health state.

4. A method according to any one of claims 1 to 3, wherein the re-evaluation step of the first threshold temperature "TemperatureStartDerating" and the second threshold temperature "TemperatureNoPower" evolve according to an increasing function of the gap between the instantaneous state of health and the target level of aging.

5. A method according to any one of claims 1 to 4, wherein the step of re-evaluating the threshold stop temperature "CoolingStopTemperature" and the threshold activation temperature "CoolingActivationTemperature" evolve according to an increasing function of the gap between the instantaneous health state and the target aging level.

6. A method according to any one of claims 1 to 5, wherein, during the re-evaluation step, the re-evaluation is a function of an instantaneous state of charge of the traction battery estimated by the battery management system.

7. A method according to any one of claims 1 to 6, wherein, during the re-evaluation step, the re-evaluation is also a function of the instantaneous state of health of the traction battery, taken alone.

8. A method according to any one of claims 1 to 7, wherein, during the re-evaluation step, at least one of the threshold temperatures among the threshold shutdown temperature, the threshold activation temperature, the first threshold temperature and the second threshold temperature is remotely re-evaluated.

9. Traction battery (1) for motor vehicle (10) comprising a battery management system (2), a thermal regulation system (3) connected to the traction battery, wherein the battery management system further comprises a computer arranged to implement the method according to any one of claims 1 to 8.

10. Motor vehicle (10) comprising a traction battery (1), a battery management system (2), a thermal regulation system (3) connected to the traction battery comprising an electric machine, characterized in that the traction battery is according to claim 9.

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