Method for meeting a durability requirement of a battery of a vehicle having an electric traction motor and corresponding battery

Abstract

A method (30) for determining an energy reserve (RES*%) in a battery of a vehicle having an electric traction motor, said method (30) comprising: - receiving a first time indication, corresponding to a beginning of life of the battery, and a second time indication; - receiving (302) a battery durability requirement (MPR SOCe-Eol ) related to a time interval configured to extend from said first time indication to said second time indication; - determining (302) a state of health of a capacity of the battery in correspondence of said second time indication; and - calculating (306) said energy reserve (RES*%) as a function of a ratio between said state of health of the capacity of the battery and said battery durability requirement (MPR SOCe-EoI ) said energy reserve (RES*%) being such as to meet, in response to a release of said energy reserve (RES*%), said battery durability requirement (MPR SOCe-EoI ) during said time interval.

Description

[0001] "Method for meeting a durability requirement of a battery of a vehicle having an electric traction motor and corresponding battery"

[0002] ★ ★ ★ ★

[0003] TEXT OF THE DESCRIPTION

[0004] Field of the Invention

[0005] The embodiments of the present disclosure refer to methods for meeting a durability requirement of a REES S ("Rechargeable Electrical Energy Storage System" ) , for example a battery, comprised in a vehicle having an electric traction motor, for example a REV ("Pure Electric Vehicle" ) .

[0006] Speci fically, various embodiments of the present description refer to solutions for estimating an energy reserve value at a beginning of li fe of said REESS , for example a minimum energy reserve value .

[0007] Known Art

[0008] The wear of the batteries in the electric vehicles leads to a reduction of the maximum energy which can be extracted from said batteries .

[0009] Said reduction is due to various factors , among which one of the most meaningful is connected to the ageing of the battery cells .

[0010] This phenomenon has a direct impact on the final customer, who will notice a progressive reduction of the vehicle driving range over time .

[0011] Therefore , various regulatory authorities are considering the introduction of speci fic requirements , to encourage manufacturers to adopt measures limiting such a phenomenon, in order to increase the useful li fe of the electric vehicles .

[0012] Such requirements are to be met at speci fic time intervals of the useful li fe of the vehicle ( for example , 8 years or 160 , 000 km, depending on which of the two limits is reached first ) . The use of an energy reserve at the beginning of li fe would represent a potentially ef fective measure for reducing the risk of non-compliance , in comparison with other corrective measures which may concern, for example , hardware modi fications , calibration of the battery cooling system, and / or the like .

[0013] The known solutions do not provide methods for dimensioning an energy reserve at a beginning of li fe in order to meet a durability requirement of the batteries comprised in vehicles having an electric traction motor, for example PEVs .

[0014] Therefore , solutions which enable meeting a durability requirement of batteries comprised in vehicles having an electric traction motor, in particular PEVs , without introducing hardware modi fications , could be advantageous to more rapidly comply with the requirements established by said regulatory authorities , while avoiding complexities and additional designing costs , by applying said solutions to di f ferent types of batteries .

[0015] Obj ect of the Invention

[0016] The invention aims at solving the technical problems mentioned in the foregoing .

[0017] Speci fically, the obj ect of the invention consists in providing a method for meeting a durability requirement of a battery of a vehicle having an electric traction motor, in particular of PEVs , by means of a method for estimating an energy reserve at a beginning of li fe of the battery .

[0018] Summary of the Invention

[0019] The obj ect of the invention is achieved by means of a method having the features set forth in the claims that follow, which are an integral part of the technical teaching provided herein in relation to the invention .

[0020] One or more embodiments refer to a corresponding battery .

[0021] Brief Description of the Figures

[0022] The invention will now be described with reference to the annexed Figures , which are provided by way o f non-limiting example only and wherein :

[0023] - Figures 1 to 3 are exemplary diagrams showing the evolution of a depth of discharge of the battery over time , and a consequent variation o f the state of charge value , according to embodiments of the present description; and

[0024] - Figure 4 is a flow chart showing an exemplary method for determining an energy reserve value adapted to meet a battery durability requirement , according to embodiments of the present description .

[0025] Detailed Description

[0026] In the description provided in the following, one or more speci fic details are illustrated in order to provide a thorough understanding of exemplary embodiments of the present disclosure . The embodiments may be obtained without one or more of the speci fic details or with other known methods , components , materials , etc . In other instances , known operations , materials or structures are not il lustrated or described in detail in order not to obscure some aspects of the embodiments .

[0027] A reference to "an embodiment" or "one embodiment" in the present description is meant to indicate that a particular configuration, structure or characteristic described with reference to the embodiment is comprised in at least one embodiment . There fore , phrases such as " in an embodiment" , " in one embodiment" or the like in various instances of the present description do not necessarily refer to one and the same embodiment .

[0028] Moreover, particular configurations , structures or characteristics may be combined in any suitable fashion in one or more embodiments .

[0029] The references used herein are provided for convenience only, and therefore they do not define the extent of protection of the scope of the embodiments .

[0030] In all the Figures annexed herein and throughout the detailed description provided in the following, unless the context dictates otherwise , the similar parts or elements are denoted by similar ref erences / numbers , and a corresponding description will not be repeated for brevity .

[0031] It is noted that the solutions described herein may be applied to any vehicle having an electric traction motor ( PEV) , that is , to any vehicle which exclusively uses electric energy for moving, and comprising one or more electric batteries configured to be charged by systems external to the vehicle .

[0032] It is noted that solutions as described herein may be applied to one or more batteries comprised in a vehicle having an electric traction motor - PEV .

[0033] As described in the foregoing, solutions according to the present disclosure aim at meeting a durability requirement of batteries comprised in vehicles having an electric traction motor, in particular PEVs , without resorting to hardware modi fications , so as to comply with the requirements established by regulatory authorities more rapidly, thus avoiding complexities and additional costs of design, and achieving the advantage of being able to use said solutions with di f ferent battery types .

[0034] Solutions as described herein concern a method for meeting a durability requirement , speci fically expressed by the SOCE ("State of Certi fied Energy" ) metric, of a battery of a vehicle having an electric traction motor , in particular a PEV, by estimating an energy reserve value at a beginning of li fe of the battery of the vehicle .

[0035] It is noted that said durability requirement is expressed with respect to an instant of End of Interval (Eol) defined with respect to the instant of beginning of life, for example an instant corresponding to a given period of time, for example 8 years after the instant of beginning of life, and / or an instant corresponding to reaching a given number of kilometres, for example 160,000 km, which have been travelled since that instant of beginning of life.

[0036] It is noted that the SOCE metric corresponds to the UBE ("Usable Battery Energy") measured or estimated at a specific instant of the life of the vehicle, and expressed as a percentage of the certified UBE.

[0037] It is noted that the REESSs may be subjected to wear generated by the aging related to charge and discharge cycles and with the chronological ageing (for example, lithium-ion REESSs) , which progressively reduce the amount of energy which is possible to extract from the REESSs.

[0038] Therefore, as described in the foregoing, various regulatory authorities are considering the introduction of requirements related to the durability of the batteries, that is, to the durability of the REESS, which consist in minimum SOCE values which are to be guaranteed in specific time intervals of the vehicle life (for example, 8 years / 160 , 000 km, depending on which of the two limits is reached first) .

[0039] If the ageing predictions of the REESS show a high risk of non-compliance with the minimum SOCE requirements which have been established, for example, by a regulatory authority or by a company desiring to comply with an internal requirement or because this is required for a specific application, it is possible to consider the use of an energy reserve at a beginning of li fe of the vehicle as a corrective action .

[0040] Therefore , embodiments of the present description refer to methods for increasing the SOCE ("State of Certi fied Energy" ) values of a REESS ("Rechargeable Electrical Energy Storage System" ) , for example a battery, comprised in a REV ("Pure Electric Vehicle" ) , that is , a vehicle which exclus ively uses electrical energy for moving, without the consumption of fossil fuels or other energy sources .

[0041] It is noted that the use of an energy reserve at a beginning of li fe leads to a reduction of the driving range of the vehicle ; therefore , it would be advantageous to limit the reserve value at a beginning of li fe to an amount which is strictly necessary to guarantee the compliance with the minimum established SOCE requirements , that is , to limit such energy reserve at a beginning of li fe to said minimum value of the energy reserve at the beginning of li fe of the battery .

[0042] Speci fically, various embodiments of the present description relate to solutions for estimating a minimum value of said energy reserve at the beginning of li fe o f the battery comprised in a PEV, that is , the minimum amount of energy reserve which enables guaranteeing to meet a minimum requirement expressed by means of the SOCE metric .

[0043] Therefore , solutions as described herein aim at providing a method for meeting a durability requirement of a battery, that is of a REESS , of a vehicle having an electric traction motor, in particular of a PEV, by dimensioning the value of an energy reserve at the beginning of li fe which enables obtaining a minimum value of energy reserve at the beginning of li fe which can meet the minimum durability requirements , for example minimum SOCE requirements , issued by the regulatory authorities or determined as a function of other purposes .

[0044] It is noted that said minimum value of energy reserve at the beginning of li fe may be determined based on predictions related to the useful li fe of the battery, operated by means of calibrated ageing models , for example with experimental data .

[0045] Solutions as described herein use a value of Depth of Discharge ( DoD) for modi fying a percentage of energy deliverable from a battery, said battery being configured for delivering, at the "Beginning of Li fe" (BoL ) , a given percentage of energy which is lower than the maximum deliverable energy .

[0046] The energy which is not delivered at the beginning of li fe of the battery, that is , the di f ference between the maximum deliverable energy and the given percentage of energy delivered at the beginning of li fe , corresponds to an energy reserve at the beginning of li fe which can be released during the useful li fe of the battery in such a way as to partly compensate for the ageing of said battery .

[0047] Said release of the energy reserve is therefore operated by increasing the value of Depth of Discharge ( DoD) of the battery .

[0048] It is noted that the release of the energy reserve at the beginning of li fe is to be completed before the instant of end of Interval (Eol ) , in such a way as to meet said battery durability requirement .

[0049] For example , it is noted that said release of the energy reserve at the beginning of li fe may be operated by a Battery Management System (BMS ) .

[0050] In the following, a list of variables will be set forth, such variables being used in the description that follows ; therefore , said variables will be described below and the description thereof will not be repeated in correspondence of their use . A first considered variable corresponds to a median value of the battery energy available at the beginning of li fe TEBoL-50%, that is , a median value of the battery energy that takes into account variabilities related to the amount of energy which can be drawn from di f ferent batteries obtained from a same production process , said variabilities being due to the production process itsel f , to the considered pack of batteries , to the storage conditions , to the ambient temperature , to the management logistics of the battery, or the like .

[0051] A further considered variable corresponds to a value of the battery energy available at the beginning of li fe and corresponding to the n-th percentile o f statistical coverage TEBoL-n%, for example , wherein the value of n may be 50% or higher, for example 95% ( thereby increasing the statistical coverage with respect to the median value ) , said statistical coverage being considered in such a way as to take into account the variabilities related to the amount of energy which can be drawn from di f ferent batteries obtained in the same production process , said variabilities being due to the production process itsel f , to the considered pack o f batteries , to the storage conditions , to the ambient temperature , to the management logistics of the battery, or the like .

[0052] A further considered variable corresponds to an Installed Battery Energy ( IBE ) , that is , to a theoretical energy value of the battery .

[0053] The installed battery energy IBE re fers to the total amount of energy that a battery can store when it i s fully charged, and considering an ideal value of depth of discharge DoD of 100% .

[0054] Indeed, in the evaluation of the installed battery energy IBE the factors related to ef ficiency losses and to the restrictions and / or limitations posed by the system are not taken into consideration .

[0055] A further considered variable corresponds to an ef ficiency of the battery system SYSBOL at the beginning of li fe .

[0056] A further considered variable corresponds to an ef ficiency of the battery system SYSEOI at said instant of end of interval Eol .

[0057] A further considered variable corresponds to an energy reserve value at the beginning of li fe RESBOL implemented in the battery of a vehicle PEV .

[0058] Said energy reserve value at the beginning of li fe RESBOL corresponds to the energy which is not delivered by the battery at the beginning of li fe , that is , an energy which cannot be used at the beginning of li fe , and which will be released over time in order to partly compensate for the battery ageing .

[0059] Said energy reserve at the beginning of li fe RESBOL may be obtained by means of a reduction of the value o f depth of discharge DoD at the beginning of li fe with respect to a reference value corresponding to a maximum energy deliverable from the battery .

[0060] A further considered variable corresponds to a state of health of the capacity of the battery SOHC-EOI related to said instant of end of interval Eol , and calculated, for example , by means of a calibrated ageing model using results of experimental tests .

[0061] A further considered variable corresponds to a state of certi fied energy SOCe-Eoi related to said instant of end of interval Eol , which is to be able to meet the battery durability requirement defined by means of a minimum SOCE value , defined as MPRcnr, ( that is , "Minimum Performance Requirement" ) .

[0062] Said minimum requirement MPRS0Cmay be established by a regulatory authority or by a company that wishes to define its own internal requirement . A further considered variable corresponds to an internal margin IM% , that is a safety margin applicable to said minimum battery durability requirement MPRSOCe Eo[in such a way as to define a target useful li fe of the battery, that is , a useful li fe which enables meeting said minimum durability requirement of the battery MP Psoce-Eoiwith a margin equal to said internal margin IM% .

[0063] A further considered variable corresponds to a correction factor CF% , that is , a correction factor applicable to said median value of the battery energy at the beginning of li fe TEBOL-5Q%, so as to estimate the value corresponding to the n-th percentile of statistical coverage TEBoL-n%.

[0064] A further considered variable corresponds to a percentage of the energy reserve at the beginning of li fe RES% , said percentage of the energy reserve at the beginning of li fe RES% corresponding to the energy, expressed as a percentage with respect to the value corresponding to the n-th percentile of statistical coverage of the battery energy TEBoL-n%, which is not delivered at the beginning of li fe of the battery and which is released over time in order to partly compensate for the ageing of said battery .

[0065] A further considered variable corresponds to a minimum percentage of the energy reserve at the beginning of li fe RES* % able to allow the achievement of a compliance with a durability requirement MPRS0C, optionally also including the internal margin IM% ; said minimum percentage of the energy reserve at the beginning of li fe RES* % corresponding to an energy expressed as a percentage with respect to the value corresponding to the n-th percentile of statistical coverage of the battery energy TEBoL-n%.

[0066] Said minimum percentage of the energy reserve at the beginning of li fe for meeting the durability requirements RES* % may be obtained as a function of the state of health of the capacity of the battery SOHC-EOI related to said instant of end o f interval Eol and to the minimum battery durability requirement MPRSOCe Eo[.

[0067] Therefore , said minimum percentage of the energy reserve at the beginning of li fe RES* % is obtained as a function of ( at least ) said minimum battery durability requirement MPRS0C, optionally including said internal margin IM% , and said state of health of the capacity of the battery SOHC-EOI , for example , as a function of a ratio between said state of health of the capacity of the battery SOHC~EOI and said minimum battery durability requirement MPRS0C, optional ly comprising said internal margin IM% .

[0068] A further considered variable corresponds to a maximum depth of discharge of the battery at the beginning of li fe DoDBoL, which does not consider the presence of a possible energy reserve .

[0069] A further considered variable corresponds to a maximum depth of discharge of the battery DoDEoIrelated to said instant of end of interval Eol , thus being a measure of an amount of charge which can be drawn from the battery .

[0070] It is noted that said depth of discharge of the battery DoDEoIrelated to said instant of end of interval Eol is di f ferent from said depth of discharge of the battery at the beginning of li fe DoDBoLi f there is a strategy for managing the li fe cycle of the battery ( that is , "Li fe Cycle Management" - LCM) .

[0071] The strategies of li fe cycle management ( LCM) of the battery may be employed for l imiting, for example , the value of maximum State of Charge ( SOC ) , that is , the maximum level of charge of the battery with respect to the capacity thereof , with the purpose of reducing the risk of events which may j eopardi ze the safety of the vehicle , and / or of a rapid deterioration of the battery, that is , of the REESS , induced by ageing phenomena .

[0072] A final considered variable corresponds to a reduced depth of discharge of the battery available at the beginning of li fe DoDBoL-res, which is obtained by considering the presence of a minimum energy reserve at the beginning of li fe RES* % which is suf ficient to achieve the compliance with the durability requirement , thus being a measure of an amount of charge which can be drawn from the battery also considering the energy reserve .

[0073] The median value of the battery energy available at the beginning of li fe TEBoL-50% may be calculated via the following equation :

[0074] TEBOL-50% — IBE ■ DODBOL■ SYSBOLwherein said median value of the battery energy available at the beginning of li fe TEBoL-50% and the installed battery energy IBE may be expressed in kilowatt-hours ( kWh) , whereas the depth of discharge of the battery at the beginning of li fe DoDBoLand the ef ficiency of the battery system at the beginning of li fe SYSBOL may be expressed as percentages ( % ) .

[0075] Similarly, it is possible to obtain a value of the battery energy available in said instant of end of interval TEEOIvia the following equation :

[0076] TEEOI= IBE ■ DODEOI■ SYSEOI■ SOHC-EOIwherein said value of battery energy available in said instant of end of interval TEEOImay be expressed in kilowatt-hours ( kWh) , whereas the depth of discharge o f the battery related to said instant of end of interval DODEOI, the ef ficiency of the battery system related to said instant of end of interval SYSEOI , and the state o f health of the capacity of the battery related to said instant of end of interval SOHC~EOI may be expressed as percentages ( % ) .

[0077] It is noted that , both here and in the part of the description which follows , the units of measurement of variables ( or the expression thereof as percentages ) for which a corresponding unit of measurement has already been provided ( or for which it has already been stated that they are expressed as percentages ) will not be repeated in order not to overburden the present description; therefore , the units of measurement ( or the expression as percentages ) already described in the foregoing will be considered valid .

[0078] The correction factor CF% may be calculated via the following equation :

[0079] CF% = 1 -TEBoL~n%

[0080] TEBOL-50% wherein said value of the battery energy corresponding to the n-th percentile of statistical coverage TEBoL-n%may be expressed in kilowatt-hours ( kWh) ; therefore , the percentage CF% can acquire only values greater than or equal to zero , that is , CF% > 0, since TEBoL-n0 / oand _5Oo / oare both positive quantities , with TEBoL-n0 / o<

[0081] The percentage of the energy reserve at the beginning of li fe RES% may be defined via the following relation :

[0082] RES% =

[0083] TEBoL -no / owherein also said value of the energy reserve at the beginning of li fe RESBoLmay be expres sed in kilowatt- hours ( kWh) ; since the percentage RES% is obtained from the ratio of positive quantities , it can acquire only values greater than or equal to zero , that is , RES% > 0 (RES% = 0 f or = 0) .

[0084] Therefore , on the basis of the previous definitions , it is possible to define the state of certi fied energy related to said instant of end of interval SOCe-Eoi via the following equation :

[0085] TEEOI

[0086] SOCe-EoI

[0087] TEBoL-5Q%■ (1 - FF5%) ■ (1 - CF%) which can be rewritten as :

[0088] „„ „ _ _ JBE ■ DQDEOI■ SYSEOI■ SOHC-EOI_ e~Eo1~ IBE ■ DODBOL■ SYSBOL■ (1 - RES° / o) ■ (1 - CF%) and, therefore :

[0089] _ DODEOI■ SYSEOI■ SOHC—Eol _

[0090] E~E01~ DODBOL■ SYSBOL■ (1 - FF5%) ■ (1 - CF%)

[0091] In order to meet said minimum battery durability requirement MPRS0C, the following relation is considered :

[0092] _ DODEOI■ SYSEOI■ SOHC—Eol _ > M PR

[0093] E~EO1~ DODBOL■ SY SBoL■ (1 - FF5%) ■ (1 - CF%) “soce-Eoi and, i f also the internal margin IM% is taken into consideration, said relation becomes :

[0094] _ DODEOI■ SYSEOI■ SOHC-Eol _

[0095] E~E°' ~ DODBOL■ SYSBOL■ (1 - FF5%) ■ (1 - CF%)

[0096] > MPRsoce-EoI+ IM% wherein said minimum battery durability requirement MPRSOCe-EoIis expressed in ( % ) .

[0097] Therefore , it is possible to obtain the minimum percentage of the energy reserve at the beginning of li fe RES* % able to respect the minimum battery durability requirement MPRS0Cvia the following formula :

[0098] RES*0 / — 1 D°DEQI BY SEOI_ SOHC-EOI_

[0099] ° " DODBOL’ SYSBOL’ (MPRSOCe-EoI) ■ (1 - CF%) which, i f also the internal margin IM% is taken into consideration, becomes :

[0100] RES*0 / — 1 D°DEQI BY SEOI_ SOHc-EoI_

[0101] ° " DODBOL’ SYSBOL’ (MPRSOCe-EoI+ / M%) ■ (1 - CF%)

[0102] Therefore , via said formula it is possible to obtain the estimate of the minimum percentage of the energy reserve at the beginning of li fe RES* % which enables obtaining, at the end of a predefined interval which ends in correspondence with said instant of end of interval Eol , a state of certi fied energy SOCe-Eoi which is equal to the minimum battery durability requirement MP Psoce-Eol' or to the minimum battery durability requirement MPRSOCe Eo[plus the internal margin IM% , i f also said internal margin IM% is taken into consideration .

[0103] It is noted that the term related to the correction factor CF% is equal to zero i f said value of the energy of the battery corresponding to the n-th percentile of statistical coverage TEBoL-n%is equal to the median value of the energy of the battery TEBOL-5O% -

[0104] It is noted that , although in the following part o f the description the expressions which take into account the internal margin IM% are considered, it is possible to easily adapt said description also to expressions which do not contain said internal margin IM% (by simply removing said contribution) .

[0105] It is noted that the reduced depth of discharge of the battery which is available at the beginning of li fe DoDBoL-res may be obtained via the following formula :

[0106] DoDsoL-res=D°DBOL ' (1—RES*%)~ wherein said reduced depth of discharge of the battery which is available at the beginning of li fe DoDBOL-res may be expressed as a percentage ( % ) .

[0107] Therefore , it is possible to obtain the following equation :

[0108] SYSEO1SOHC-EOI_ DoDBoL-res— DODEOI■ — — O 1 'BOL (MPRSOCe-EoI+ / M%) ■ (1 - CF%)

[0109] It is noted that it is possible to simpli fy the equations provided in the foregoing i f the ef ficiency of the battery system at the beginning of li fe SYSBOL i s equal to the ef ficiency of the battery system related to said instant of end of interval SYSEOI, that IS , considering that the reduction of the battery efficiency during the li fe cycle of the battery is negligible :

[0110] DODEOISOH(C-Eol

[0111] RES*% = 1 - ■{MpRsQCe Eoi + / Mo / o).(1_CF%) _ SOHC-EOI_

[0112] DODBOL-res — DODEOI

[0113] ■ (MPRSOCe-EoI+ / M%) ■ (1 - CF%)

[0114] It is noted that it is also possible to simplify the equations provided in the foregoing if an LCM strategy is not present, that is, if the depth of discharge of the battery at the beginning of life DoDBoLis equal to the depth of discharge of the battery related to said instant of end of interval DoDEoI: SYSEoISOHC EOIRES*% = 1 -

[0115] 'BoL (MPRsOC,

[0116] It is noted that, if both simplifications are implemented simultaneously, that is, if both the conditions described in the foregoing are met, it is possible to obtain the following equations:

[0117] SOHC_

[0118] P / 7 C*0 / 1 _uEc,OUIi _

[0119] ° " (MPRSOCe-EoI+ / M%) ■ (1 - CF%)

[0120] DoDBoL-res= DODEOI-SOHC-EOI -

[0121] BOL res Eol (MPRSOCe EoI + IM%) ■ (1 - CF%) It is noted that, if the term related to the correction factor CF% is equal to zero, it is possible to obtain the following equations:

[0122] SOHC EOI

[0123] RES*% = 1 -

[0124] (MPRSOCe-EoI+ / M%)

[0125] FOHC—Eol

[0126] DODBOL-res — DODEOI

[0127] (MPRSOCe-EoI+IM%)

[0128] Moreover, if the value of said state of certified energy at said instant of end of interval SOCe-EoIis already greater than or equal to said minimum battery durability requirement MPRS0C, optionally also considering the internal margin IM% (SOCe-EoI> MPRSOCe-EoIor SOCe-EoI> MPRSOCe-EoI+ IM%) , then an energy reserve is not necessary to meet said minimum battery durability requirement MPRS0C E [fand therefore FF5*% = 0.

[0129] Figure 1 is an exemplary diagram 10 showing the evolution of a depth of discharge of the battery DoD over time t, and a consequent variation of the value of the state of charge SoC, according to embodiments of the present description.

[0130] It is noted that in the exemplary diagram 10 of Figure 1, for simplicity, the presence of an LCM strategy is not taken into account; therefore, the maximum available depth of discharge of the battery DoD is considered as constant during the useful life of the battery of the vehicle.

[0131] Moreover, it is noted that said exemplary diagram 10 in Figure 1 considers a situation wherein the ageing predictions of the REESS reveal a high risk of non- compliance of the value of the state of certified energy related to said instant of end of interval SOCe-Eoi with respect to the minimum battery durability requirement MP Rsoce. _Eo[defined by means of the SOCE metric.

[0132] Therefore, a minimum energy reserve at the beginning of life RES*% is taken into consideration and, in correspondence of said instant of the beginning of life BoL, there is a reduction of the corresponding depth of discharge DoD by an amount which is proportional to the capacity of said minimum energy reserve at the beginning of life RES*%.

[0133] In response to the reduction of the depth of discharge of the battery at the beginning of life DoDBoLdown to the value of the reduced depth of discharge of the battery at the beginning of life DoDBoL-res, the state of charge SoC is reduced, at the beginning of life, from a maximum value SoCmax-BOL to a reduced value SoCmax-BOL-res , in order to consider the presence of the minimum energy reserve at the beginning of life RES*%.

[0134] It is possible to obtain the value of the reduced depth of discharge of the battery at the beginning of life DODBOL-res •

[0135] (see, for example, the exemplary diagram 10 in

[0136] Figure 1) by reducing the SOCmaxto a value SOCmax-BoL-res, (see, for example, the exemplary diagram 20 in Figure 2) by increasing the SOCminup to a value SOCmin_ BoL-res, and / or

[0137] (see, for example, the exemplary diagram 40 in Figure 3) by acting on both the parameters, that is, by reducing the SOCmaxdown to a value SOCmax-BoL-res and by increasing the SOCminup to a value SOCmin-BoL-res • Therefore, at the beginning of life, the value of the state of charge SoC may vary:

[0138] (see, for example, the exemplary diagram 10 of Figure 1) between a minimum value of state of charge SoCmin-BoL and said reduced state of charge SoCmax-BoL-res /

[0139] (see, for example, the exemplary diagram 20 in Figure 2) between a minimum value of state of charge SoCmin-BoL-res and said reduced state of charge SoCmax, and / or

[0140] (see, for example, the exemplary diagram 40 in Figure 3) between a minimum value of state of charge SoCmin-BoL-res and said reduced state of charge SoCmax-BoL-res • As the values of time t increase with respect to the instant of beginning of life BoL, the depth of discharge DoD of the battery is increased, so as to partly compensate for the predicted ageing, by progressively releasing the minimum energy reserve at the beginning of life RES*%.

[0141] Indeed, the release of the minimum energy reserve at the beginning of life RES*% is associated with the progressive increase of the depth of discharge DoD of the battery, which partly compensates for the ageing of the REESS.

[0142] Said increase of the depth of discharge DoD proceeds until the original value of depth of discharge is reached, that is, until the original value of the maximum depth of discharge of the battery at the beginning of life DoD is reached.

[0143] It is noted that the complete release of the minimum energy reserve at the beginning of li fe RES* % has to take place before the instant of end of interval Eol ( or at said instant of end of interval Eol ) to which the minimum battery durability requirement MPRSOCe Eo[is associated .

[0144] It is noted that , i f said release of the minimum energy reserve at the beginning of li fe RES* % has not been completed before ( or in correspondence of ) the instant of end of interval Eol , the capacity of said energy reserve is not used in its entirety and, therefore , it would not be possible to meet the minimum battery durability requirement MPRS0C e-Eo[.

[0145] For example , said release o f the minimum energy reserve at the beginning of li fe RES* % , that is , the progressive increase of the depth of discharge DoD of the battery during ageing, may be managed by a Battery Management System (BMS ) or via a control unit of the vehicle , or the like .

[0146] Figure 4 is a flow chart 30 , which begins at a starting step 300 and ends at an ending step 310 , showing an exemplary method for determining a value of energy reserve RES* % able to meet a battery durability requirement MPRS0Caccording to embodiments of the present disclosure .

[0147] Said method 30 may comprise a variable determination block 302 which may be configured to receive said minimum battery durability requirement MP Psoce-Eoiand, optionally, the internal margin IM% , in order to determine a plurality of variables PV ( or to recover them from external elements and / or to store them in the memory) , and to provide said plurality of variables PV and said minimum battery durability requirement MPRS0C, optionally associated with the internal margin IM% , to a comparison block 304 .

[0148] It is noted that said plurality of variables PV may comprise the variables to be used to calculate the minimum percentage of the energy reserve at the beginning of li fe RES* % , said plurality of variables being determined based on the relation considered for such calculation out of the relations described in the foregoing .

[0149] Said plurality of variables PV may comprise the state of health of the capacity of the battery related to said instant of end of interval SOHC~EOI and the maximum depth of discharge of the battery at said instant of end of interval DoDEoI.

[0150] For example , i f the term related to the correction factor CF% is not equal to zero , said plurality of variables PV may further comprise said correction factor CF% .

[0151] For example , i f an LCM strategy is present , said plurality of variables PV may further comprise the maximum depth of discharge of the battery at the beginning of li fe DoDBoL, which is di f ferent from the depth of discharge of the battery related to said instant of end of interval DoDEoI.

[0152] For example , i f a reduction of the battery ef ficiency over time is considered, said plurality of variables PV may further comprise the ef ficiency of the battery system at the beginning of li fe SYSBOL and the ef ficiency of the battery system related to said instant of end of interval SYSEOI .

[0153] It is noted that said plurality of variables PV may further comprise the variables to be used to calculate the value of the state of certi fied energy related to said instant of end of interval SOCe-Eoi , for example according to the relation described in the foregoing .

[0154] For example , said value o f the state of certi fied energy related to said instant of end of interval SOCe- EOI may be obtained via one of the formulae described in the foregoing; therefore , said plurality of variables PV may comprise one or more variables out of the depth of discharge of the battery related to said instant of end of interval DoDEoI, the ef ficiency of the battery system related to said instant of end of interval SYSEOI , the state of health of the capacity of the battery SOHC-EOI related to said instant of end of interval Eol , the depth of discharge of the battery at the beginning of li fe DoDBoL, the ef ficiency of the battery system at the beginning of li fe SYSBOL , the percentage of the energy reserve at the beginning of li fe RES% , and the correction factor CF% .

[0155] It is noted that said percentage of the energy reserve at the beginning of li fe RES% is initially set to a value equal to zero , in such a way as not to consider a reserve and to veri fy whether said minimum battery durability requirement MPRS0Cis met by the battery even without using said reserve .

[0156] The comparison block 304 may be configured to receive said plurality of variables PV and said minimum battery durability requirement MPRS0C, optionally associated with the internal margin IM% , from the variable determination block 302 .

[0157] Said comparison block 304 may be configured to determine , for example via predictions related to the battery ageing, the value of the state of certi fied energy related to said instant of end of interval SOCe-EoI, and to compare said value of the determined state o f certi fied energy SOCe-Eoi with the minimum battery durability requirement MPRS0Cdefined by means of the SOCE metric, optionally added to the internal margin IM% .

[0158] I f said value of the state of certi fied energy related to said instant of end of interval SOCe-Eoi ( calculated considering an energy reserve at the beginning of li fe RES% equal to zero ) is greater than or equal to said minimum battery durability requirement MP Psoce-Eoi' optionally added to the internal margin IM% , that is , i f :

[0159] SOCe-EoI> MPRSOCe-EoIor SOCe-EoI> MPRSOCe-EoI+ IM%, then an energy reserve is not required to meet said minimum battery durability requirement MPRS0C, optionally also considering the internal margin IM% ; therefore the method proceeds , following the branch denoted with the reference Y3in Figure 4 , towards a first reserve calculation block 308 .

[0160] Otherwise , i f said value of the state of certi fied energy related to said instant of end of interval SOCe- EOI is lower than said minimum battery durability requirement MPRS0C, optionally added to the internal margin IM% , an energy reserve is required for meeting said minimum battery durability requirement MPRSOCe Eo[, optionally also considering the internal margin IM% ; therefore , the method proceeds , following the branch denoted as N3in Figure 4 , towards a second reserve calculation block 306 , for example by sending also said plurality of variables PV and said minimum battery durability requirement MPRS0C, optional ly associated with the internal margin IM% , to said second reserve calculation block 306 via the branch denoted as N3.

[0161] The first reserve calculation block 308 may be configured :

[0162] - to set said minimum percentage of the energy reserve at the beginning of li fe RES* % to zero , that is , RES*% = 0,

[0163] - to set the value of the reduced depth of discharge of the battery at the beginning o f li fe DoDBoL-resto the value of the maximum depth of discharge of the battery at the beginning of li fe DoDBoL, that is , DoDBoL-res= DoDBoL, and - to end the method 30 , proceeding to the end step

[0164] 310 .

[0165] The second reserve calculation block 306 may be configured :

[0166] - to calculate the minimum percentage of the energy reserve at the beginning of li fe RES* % via one of the relations described in the foregoing,

[0167] - to calculate the value of the reduced depth o f discharge of the battery at the beginning of li fe DoDBoL_ res via one of the relations described in the foregoing, and

[0168] - to end the method 30 , proceeding to the end step 310 .

[0169] For example , said second reserve calculation block 306 may be configured to implement the following relations :

[0170] RES*% = 1 -SOHc~Eo1and DoDBoL-res= DoDEoI■S0Hc~E°l

[0171] MPRsoce-EoIB0L res E01MPRSOCe-EoIor

[0172] RES*% = 1 - - -S0Hc~e°‘ - and DoDBoL-res= DoDEoI■

[0173] (MPRSOCe-EoI+IM%)B0L res b 01

[0174] SOHC-EOI _

[0175] (MPRSOCe-EoI+IM%)

[0176] Alternatively, said second reserve calculation block 306 may be configured to implement any one of the equations described in the foregoing for calculating the minimum percentage of the energy reserve at the beginning of li fe RES* % and the reduced depth of discharge of the battery at the beginning of li fe DoDBoL-res.

[0177] To sum up, solutions as described in the present document enable obtaining a method 30 for determining an energy reserve , for example , the energy reserve at the beginning of li fe RES% or the percentage of the energy reserve at the beginning of li fe RES* % , in a battery o f a vehicle having an electric traction motor .

[0178] Said method 30 comprises the following operations :

[0179] - receiving a first time indication corresponding to a beginning of life of the battery, that is, said instant of beginning of life BoL, and a second time indication, that is, said instant of end of interval Eol, for example, an instant which is defined with respect to the instant of the beginning of life (for example, by a regulatory authority) ; receiving, for example, from the variable determination block 302, a battery durability requirement, that is, the minimum battery durability requirement MPRS0C(defined in correspondence of a time interval, for example, the interval between said instant of beginning of life BoL and said instant of end of interval Eol - for example, 8 years - and of a travelled distance - for example, 160,000 km) , related to a time interval configured to extend from the first time indication BoL to the second time indication Eol;

[0180] - determining, for example, again via the variable determination block 302, a state of health of a capacity of the battery SOHC-EOI in correspondence of said second time indication Eol; and

[0181] - calculating, for example, via the second reserve calculation block 306, the energy reserve RES% or RES*% as a function of a ratio between the state of health of the capacity of the battery SOHC-EOI and the battery durability requirement MPRS0C e-Eo[.

[0182] The energy reserve RES% or RES*% determined via the method 30 is such as to meet, in response to a release of said energy reserve RES% or RES*% (for example, in response to a gradual release of said reserve by means of the increase of the value of depth of discharge DoD over time) , the battery durability requirement MPRSOCe Eo[during said time interval, therefore enabling obtaining a battery durability complying with a requirement.

[0183] Said release operation may be performed by increasing a value of depth of discharge DoD of the battery .

[0184] In embodiments of the present disclosure , said value of depth of discharge DoD of the battery may be obtained, in correspondence of the first time indication BoL ( that is , at the instant when said value of depth of discharge DoD of the battery corresponds to the reduced value of depth of discharge of the battery at the beginning of li fe DoDBoL-res) , as a function of :

[0185] - said ratio between the state of health of the capacity of the battery SOHC-EOI and the battery durability requirement MPRS0C E I; and

[0186] - a value of depth of discharge of the battery, that is , the value of depth of discharge of the battery related to said instant of end of interval DoDEoI, indicative of a percentage of energy deliverable from the battery ( for example , with respect to a maximum capacity of said battery) in correspondence of the second time indication Eol .

[0187] It is noted that , as described in the foregoing, in the previous equations said value of depth of discharge DoD of the battery in correspondence of the first time indication BoL, that is , said value of the reduced depth of discharge of the battery at the beginning of li fe DoDBoL-res , may be obtained also by considering additional variables .

[0188] For example , said value of depth of discharge DoD of the battery in correspondence of the first time indication BoL may be obtained by considering also the internal margin IM% , the correction factor CF% , the ef ficiency of the battery system at the beginning of li fe SYSBOL , and / or the ef ficiency of the battery system related to said instant of end of interval SYSEOI .

[0189] In embodiments of the present disclosure , the energy reserve RES% or RES* % may be equal to zero , for example , set to zero by the first reserve calculation block 308 , i f the state of health of the capacity of the battery SOHC-EOI is greater than or equal to , for example , such a comparison operation being executed in the comparison block 304 , the battery durability requirement MPRSo0uCce— E „QI , .

[0190] In embodiments of the present description, said method 30 may comprise : receiving, for example , via the variable determination block 302 , a margin value IM% ; and adding, for example , via the second reserve calculation block 306 , the margin value IM% to the battery durability requirement MPRS0C, obtaining a durability requirement with margin, that is , the sum MPRS0C„ , + IM% .

[0191] In this case , the operation of calculating, for example , again via said second reserve calculation block 306 , the energy reserve RES% or RES* % is performed as a function of a ratio between the state of health of the capacity of the battery SOHC-EOI and the durability requirement with margin .

[0192] In embodiments of the present disclosure , said method 30 may comprise : determining, for example , via the variable determination block 302 , in correspondence of the first time indication BoL, a median energy value , that is , the median value of the battery energy TEBOL-5Q%, of a plurality of batteries ( for example , comprising batteries obtained in the same production process ) comprising said considered battery; determining, for example , via said variable determination block 302 , in correspondence of the first time indication BoL, an energy value related to a given statistical coverage , that is , the value of the battery energy corresponding to the n-th percentile of statistical coverage TEBoL-n%, of the plurality of batteries comprising the considered battery; and determining, for example , via said variable determination block 302 , a correction factor CF% as a function of a ratio between the energy value related to the given statistical coverage TEBoL-n% and the median energy value TEBoL-50%.

[0193] In this case , the operation of calculating, for example , via said second reserve calculation block 306 , the energy reserve RES* % is further performed as a function of the correction factor CF% .

[0194] In embodiments of the present disclosure , said method 30 may comprise : determining, for example , via said variable determination block 302 , a first depth of discharge value , that is , the value of the maximum depth o f discharge of the battery at the beginning of li fe DoDBoL, of the battery, indicative of a first percentage o f energy deliverable from the battery in correspondence of the first time indication BoL ; and determining, for example , via said variable determination block 302 , a second depth of discharge value , that is , the value of the depth of discharge of the battery related to said instant of end of interval DODEOI, of the battery, indicative of a second percentage of energy deliverable from the battery in correspondence of the second time indication Eol .

[0195] In this case , the operation of calculating, for example , via said second reserve calculation block 306 , the energy reserve RES* % is further performed as a function of a ratio between the second depth of discharge value DODEOIand the first depth of discharge value DoDBoL.

[0196] In embodiments of the present disclosure , said method 30 may comprise : determining, for example , via said variable determination block 302 , in correspondence of the first time indication BoL, a first battery ef ficiency, that is , the ef ficiency of the battery system SYSBOL at the beginning of li fe ; and determining, for example , via said variable determination block 302 , in correspondence of the second time indication Eol , a second battery ef ficiency, that is , the ef ficiency of the battery system SYSEOI at said instant of end of interval Eol .

[0197] In this case , the operation of calculating, for example , via said second reserve calculation block 306 , the energy reserve RES* % is further performed as a function of a ratio between the second battery efficiency SYSEOI and the first battery ef ficiency SYSBOL -

[0198] In embodiments of the present disclosure , the energy reserve RES* % may be the minimum energy reserve that meets , in response to a release of said energy reserve RES* % ( for example , as a function of the increase of the depth of discharge DoD of the battery) , the battery durability requirement MPRSOCe Eo[during the time interval , that is during the time interval extending from the beginning of li fe BoL to the end of the reference interval Eol .

[0199] Therefore , the solution described in the present document enables defining a method for obtaining the duration of a useful li fe of a REESS which complies with a given requirement by estimating an energy reserve to be considered at the beginning of li fe of the REESS comprised in the vehicle .

[0200] It is noted that embodiments of the present disclosure refer to a battery comprised in a vehicle having an electric traction motor, for example a REV, and configured to comprise an energy reserve RES% or RES* % determined by means of the method 30 described in the foregoing .

[0201] Hence , it can be understood that the solution set forth in the present detailed description may enable meeting a durability requirement of batteries comprised in vehicles having an electric traction motor, in particular PEVs , without resorting to hardware modi fications , so as to comply with the requirements established by regulatory authorities more rapidly, avoiding designing complexities and additional costs , and obtaining the possibility of applying said solutions to di f ferent types of batteries . Without prej udice to the basic principles , the details and the embodiments may vary, even appreciably, with respect to what has been described, by way of example only, without departing from the extent of protection . The extent of protection is defined by the annexed claims .

Claims

CLAIMS1. Method (30) for determining an energy reserve (RES%; RES*%) in a battery of a vehicle having an electric traction motor, said method (30) comprising: receiving a first time indication corresponding to a beginning of life of the battery (BoL) and a second time indication (Eol) ; receiving (302) a battery durability requirement (MPRS0C E I) related to a time interval configured to extend from said first time indication (BoL) to said second time indication (Eol) ; determining (302) a state of health of a capacity of the battery (SOHC-EOI) in correspondence of said second time indication (Eol) ; and calculating (306) said energy reserve (RES%; RES*%) as a function of a ratio between said state of health of the capacity of the battery (SOHC-EOI) and said battery durability requirement (MPRS0C) ; said energy reserve (RES%; RES*%) being such as to satisfy, in response to a release of said energy reserve (RES%; RES*%) , said battery durability requirement (MPRS0C) during said time interval.

2. The method (30) according to claim 1, wherein the operation of releasing is performed by increasing a depth of discharge (DoD) value of the battery.

3. The method (30) according to claim 2, wherein said depth of discharge (DoD; DoDBoL-res) value of the battery in correspondence of said first time indication (BoL) is obtained (306) as a function of: the ratio between said state of health of the capacity of the battery (SOHC-EOI) and said battery durability requirement (MPRS0C) ; and a depth of discharge (DoDEoI) value of the battery indicative of a percentage of energy deliverablefrom the battery in correspondence of said second time indication (Eol) .

4. The method (30) according to any one of the previous claims, wherein said energy reserve (RES%; RES*%) is equal to zero (308) if said state of health of the capacity of the battery (SOHC-EOI) is greater than or equal to (304) said battery durability requirement (MPRS0C F,) .

5. The method (30) according to any one of the previous claims, comprising: receiving (302) a margin value (IM%) ; and adding (306) said margin value (IM%) to said battery durability requirement (MPRSOCe Eo[') , obtaining a durability requirement with margin; wherein the operation of calculating (306) said energy reserve (RES%; RES*%) is performed as a function of a ratio between said state of health of the capacity of the battery (SOHC-EOI) and said durability requirement with margin.

6. The method (30) according to any one of the previous claims, comprising: determining (302) , in correspondence of said first time indication (BoL) , a median energy value (TEBoL_ 50%) of a plurality of batteries comprising said battery; determining (302) , in correspondence of said first time indication (BoL) , an energy value related to a given statistical coverage (TEBoL-xx%) of said plurality of batteries comprising said battery; and determining (302) a correction factor (CF%) as a function of a ratio between said energy value related to the given statistical coverage (TEBoL-n%) and said median energy value (TEBoL-5o%) ; wherein the operation of calculating (306) said energy reserve (RES%; RES*%) is further performed as a function of said correction factor (CF%) .

7. The method (30) according to any one of the previous claims, comprising: determining (302) a first depth of discharge (DODBOL) value of the battery indicative of a first percentage of energy deliverable from the battery in correspondence of said first time indication (BoL) ; and determining (302) a second depth of discharge (DODEOI) value of the battery indicative of a second percentage of energy deliverable from the battery in correspondence of said second time indication (Eol) ; wherein the operation of calculating (306) said energy reserve (RES%; RES*%) is further performed as a function of a ratio between said second depth of discharge (DoDEoI) value and said first depth of discharge (DODBOL) value.

8. The method (30) according to any one of the previous claims, comprising: determining (302) , in correspondence of said first time indication (BoL) , a first battery efficiency (SYSBOL) ; and determining (302) , in correspondence of said second time indication (Eol) , a second battery efficiency (SYSEOI) ; wherein the operation of calculating (306) said energy reserve (RES%; RES*%) is further performed as a function of a ratio between said second battery efficiency (SYSEOI) and said first battery efficiency (SYSBOL) •9. The method (30) according to any one of the previous claims, wherein said energy reserve (RES*%) is the minimum energy reserve that meets, in response to a release of said energy reserve (RES%; RES*%) , said battery durability requirement (MPRSOCe Eo[) during said time interval.

10. A battery comprised in a vehicle having an electric traction motor, said battery being configured to comprise an energy reserve (RES%; RES*%) determined via the steps of the method (30) according to any one of the previous claims.

Images