A method for estimating a charging time of a battery of a vehicle having an electric traction motor, and a corresponding vehicle

Abstract

A method for estimating a charging time of at least one battery comprised in a vehicle having an electric traction motor, said method comprising: - determining (206) a profile of a current absorbed by the at least one battery (IBatt_est) during a charging phase of said at least one battery; - determining an actual state of charge of the at least one battery; - simulating (208) said charging phase of the at least one battery as a function of said profile of the current absorbed by the at least one battery (IBatt_est), of said actual state of charge of the at least one battery, of an electrical capacity of the at least one battery, and of a simulation time, obtaining an estimate of the state of charge (SOCest) of the at least one battery; and - identifying (216) as charging time of the at least one battery a difference between a first simulation time value corresponding to an estimate of the state of charge (SOCest) of the at least one battery equal to a final state of charge of said at least one battery and a second simulation time value corresponding to an estimate of the state of charge (SOCest) of the at least one battery equal to said actual state of charge of the at least one battery.

Description

[0001] "A method for estimating a charging time of a battery of a vehicle having an electric traction motor, and a corresponding vehicle"

[0002] ****

[0003] TEXT OF THE DESCRIPTION

[0004] Field of the Invention

[0005] The embodiments of the present description refer to methods for estimating a charging time of a battery of a vehicle having an electric traction motor .

[0006] Known Art

[0007] Obtaining an estimate of the charging time of a battery of a vehicle having an electric traction motor may be advantageous, since said estimate may allow a driver of said vehicle to know in advance how long he will have to wait before the end of the vehicle charging, and therefore to organize his / her activities depending on said charging time .

[0008] A value which iiss normally considered for calculating said charging time is the actual w "State of Charge" (SOC) of the battery, i . e . the actual level of charge of an electric battery expressed with respect to the capacity thereof, for example as a percentage, wherein a percentage of 0% corresponds to a flat battery, whereas aa percentage of 100% corresponds to aa fully charged battery.

[0009] Starting from such definition, it is possible to define a variation of the state of charge to be charged as a difference between a state of charge corresponding to a fully charged battery (or to a battery having a target level of charge) and an actual state of charge of the battery, ii .. ee .. the level of charge which is still lacking in an electric battery expressed with respect to the capacity thereof (or with respect to said target level of charge) , for example as a percentage, wherein a percentage of 0% corresponds to a fully charged battery (or to a battery charged up to said target level of charge) , while a percentage of 100% corresponds to a flat battery.

[0010] Known solutions allow estimating said charging time by means of a direct ratio between:

[0011] - the product of said variation of the state of charge. to be charged during a corresponding battery charging phase, and the battery capacity; and

[0012] - a current absorbed by the battery.

[0013] A problem of said known solutions resides in the fact that such estimate of the charging time is not obtained with accuracy, since the current absorbed by the battery is not constant during said charging phase.

[0014] Said problem causes an inconvenience to the driver of a vehicle having an electric traction motor, since it is difficult to know in advance how long it will actually take to reach the end of the charging phase of the vehicle, and therefore the driver cannot plan his / her activities during said charging phase of the vehicle.

[0015] Solutions for obtaining a more accurate estimate of said charging time of the battery of a vehicle having an electric traction motor may be advantageous in order not to cause the inconveniences described in the foregoing to the driver.

[0016] Object of the Invention

[0017] The invention aims at solving the technical problems outlined in the foregoing. Specifically, the object of the invention consists in providing a method for estimating a charging time of a battery of a vehicle having an electric traction motor in a more accurate way than in the known solutions .

[0018] Summary of the Invention

[0019] The object 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 vehicle .

[0021] Brief Description of the Figures

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

[0023] - Figure 1 is a graph showing an exemplary profile of the current absorbed by the battery as a function of the state of charge of the battery, according to embodiments of the present description;

[0024] - Figure 2 is a block diagram showing an exemplary model for a simulation of the charging phase of the battery, according to embodiments of the present description;

[0025] - Figure 3 iiss a diagram showing aa mmeetthhoodd for obtaining a target battery Input current considering strategies used for the charging phase of the battery, according to embodiments of the present description;

[0026] - Figure 4 is a diagram showing an exemplary method for obtaining a current generated by a charging element, according to embodiments of the present description;

[0027] - Figure 5 is a block diagram showing the relationships existing between a block of a thermal model of the battery and a block for estimating the battery temperature according to embodiments of the present description;

[0028] - Figure 6 is an exemplary model of a battery cell according to embodiments of the present description;

[0029] - Figure 7 is a graph showing an exemplary behaviour of the battery temperature during a charging phase of said battery, according to embodiments of the present description;

[0030] - Figure 8 is a diagram of an exemplary method for obtaining a thermal conditioning power provided by an electric heater for heating the battery, according to embodiments of the present description;

[0031] - Figure 9 is a diagram of an exemplary method for obtaining a thermal conditioning power provided by a cooling circuit for cooling the battery, according to embodiments of the present description;

[0032] - Figure 10 is a graph showing, from a qualitative point of view, an exemplary simulation of the battery temperature as a function of a simulation time, according to embodiments of the present description; and

[0033] - Figure 11 is a graph showing, from a qualitative point of view, an exemplary simulation of the state of charge of the battery as a function of a simulation time, according to embodiments of the present description.

[0034] Detailed Description

[0035] In the following description one or more specific details are given in order to provide a thorough understanding of exemplary embodiments of the present description. The embodiments may be implemented without one or more of the specific details, or with other methods, components, materials, etc. In other cases, well-known operations, materials or structures are not shown or described in detail in order not to obscure various aspects of the embodiments .

[0036] A reference to "an embodiment" or "one embodiment* within the present description indicates that a particular configuration, structure or characteristic described with reference to the embodiment is comprised in at least one embodiment . Therefore, phrases such as "in an embodiment* or "in one embodiment* and the like, which may be present in one or more points of the present description, are not necessarily all referred to one and the same embodiment .

[0037] Moreover, particular configurations, structures or characteristics may be combined in any suitable fashion In one or more embodiments .

[0038] The headings provided herein are for convenience only, and therefore they do not limit the extent of protection or the scope of the embodiments .

[0039] Throughout 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 references / numbers, and a corresponding description will be omitted for the sake of brevity.

[0040] It should be noted that the solution described herein may be applied to any vehicle having an electric traction motor and comprising an electric battery configured to be charged by systems external to the vehicle .

[0041] As described in the foregoing, solutions as described in the present document have the purpose of providing a method for estimating a charging time of a battery of a vehicle having an electric traction motor with improved accuracy with respect to the known solutions .

[0042] Such estimate of the charging time of the battery is carried out by means of a method which may be configured to provide such estimate both during a charging phase with alternate current (AC) and during a charging phase in direct current (DC) .

[0043] Moreover, said method may be further configured to provide an indication about the state of charge, for example by indicating whether the vehicle having an electric traction motor is or is not in a charging phase. Solutions as described herein are based on the forecast of an expected profile of the current flowing in the battery, i.e. an expected profile of the current absorbed by the battery, during a charging phase of said battery. The estimate of the charging time of the battery is therefore obtained as a function of said expected profile .

[0044] It is noted that, during the charging phase of the battery, the current absorbed by the battery lBatt rarely remains constant; therefore, also the profile derived therefrom is not constant .

[0045] Figure 1 is a graph showing an exemplary profile 10 of the current absorbed by the battery lBatt, for example expressed in amperes (A) , as a function of the state of charge SOC of the battery, for example expressed as a percentage (%) .

[0046] The value of said current absorbed by the battery lBatt depends on:

[0047] - the value of the state of charge SOC of the battery, specifically, said current absorbed by the battery lBatt decreases in response to an increment of the state of charge SOC, and

[0048] - a battery temperature TBatt, which varies during the charging phase, specifically, said current absorbed by the battery lBatt increases in response to an increment of the battery temperature TBatt .

[0049] In addition, also the high voltage loads (HV loads) may absorb current from a charging element, for example from a charging station for vehicles having an electric traction motor, and they may cause variations of the current absorbed by the battery lBatt.

[0050] In order to obtain said estimate of the charging time, solutions as described herein are further based on simulations of the charging phase of the battery, which are carried out (e.g. locally, i.e. within the vehicle itself) in such a way as to process input signals or values which are generated and / or updated during the execution of the simulation itself . Specifically, said simulation is configured to process input signals serially. in the order in which such signals are provided to the simulation, without having the totality of said input signals already available at the beginning of the simulation, ii..ee.. ,, wherein ssaaiidd Iinnppuutt signals are generated aanndd / / oorr updated dduurriinngg cycles of the simulation .

[0051] Such simulations may be performed by using a model of the battery which, in order to obtain accurate results, may be either an electrical or a thermal model of the battery, and may comprise high-voltage loads . Moreover, the strategies used for the charging phase are taken into consideration in the simulations as well .

[0052] Figure 2 is a block diagram 20 illustrating an exemplary model for a simulation of the charging phase of the battery, according to embodiments of the present description .

[0053] A time window block 202 may be configured to provide a time step to other blocks of the model that require timing. Specifically, said time window block 202 may be configured to provide said time step to a battery state of charge estimation block 208, to a battery model block 210, to a battery temperature estimation block 214, and to a battery charging time estimation block 216.

[0054] Said time step used for the timing of the simulation advantageously corresponds to an amount of time longer than the time required for the execution of the method. In this way it is possible to predict the estimated charging time and to communicate it to a driver in a short time, before the charging phase is ended.

[0055] It is noted that the values provided as Input to any block comprised in the model of Figure 2 may be considered constant during each of the time steps .

[0056] It is noted that the value of said time step may be determined according to the application which makes use of the method of the solution as described herein. In fact, the choice of the value of said time step depends on a desired compromise between the accuracy and the duration of the estimate. In fact, a shorter time step may favour a higher accuracy but, at the same time, it may lead to a longer duration of the estimate, and vice versa.

[0057] A battery limit current block 204 may be configured to receive, from the battery state of charge estimation block 208, an estimate of the state of charge SOCeet of the battery and, from the battery temperature estimation block 214, an estimate of the battery temperature TBatt_est .

[0058] Said battery limit current block 204 may be configured to calculate a target battery input current TBatt_Tgt based on said received estimate of the state of charge SOCeet and on said received estimate of the battery temperature TBatt_est, and to provide said target battery input current TBatt_Tgt to a battery current estimation block 206.

[0059] Said target bbaatttteerryy input current TBatt_Tgt may further depend on the strategies implemented for the charging phase. Specifically, said target battery input current TBatt_Tgt may be limited as a ffuunnccttiioonn of a currently considered charging strategy.

[0060] Figure 3 is a diagram 30 showing a method for obtaining said target battery input current TBatt_Tgt considering the strategies implemented for the charging phase of the battery.

[0061] Said target battery input current TBatt_Tgt may be limited by:

[0062] - a limitation TBatt_Lim required by strategies implemented in the charging phase to limit the battery input current with respect to a maximum value which can be absorbed by a cell of said battery, said maximum value being extracted from a map which expresses limit values of the battery Input current TBatt_Lim as a function of a temperature of the battery cells TBatt , i.e. of the estimate of the battery temperature TBatt_esm, and of the state of charge SOC of the battery, i.e. of the estimate of the state of charge SOCest;

[0063] - a limitation required by a driver Batt_Lim_Driver , which may be configured to limit the battery input current in order to preserve a health state of the battery; and

[0064] - a limitation l Batt_Lim_ChrgStrg required by strategies implemented in the charging phase to limit the battery input current to minimize the charging time of the battery and / or the waiting time of a driver before he / she can restart the vehicle after a charging phase, l.e. by minimizing the time required both from the charging phase and from a subsequent conditioning phase of the battery.

[0065] Therefore, said target battery input current TBatt_Tgt may be obtained via a first minimization function Mi applied to the limitations described in the foregoing, thus :

[0066] The battery current estimation block 206 may be configured to receive, from said battery limit current block 204, the target battery input current TBatt_Tgt and, from said battery temperature estimation block 214, the estimate of the battery temperature TBatt_est .

[0067] Said battery current estimation block 206 may be configured to calculate an estimate of the battery input current TBatt_est based on said received target battery input current TBatt_Tgt and based on said received estimate of the battery temperature TBatt_est, and to provide said estimate of the battery input current TBatt_est to the battery state of charge estimation block 208.

[0068] The estimate of the battery input current TBatt_est may be calculated via the Kirchhoff' s first law. In fact. said battery input current lBatt_est may be obtained through a difference between :

[0069] - a current generated by a charging element Icharger, for example a charging station for vehicles having an electric traction motor, and

[0070] - currents which are absorbed by high voltage loads, e . g. at least one of a current absorbed by an electric compressor IeAC, aa current absorbed by the electric coolant heater IECH, and / or a current absorbed by a DC- DC converter IDCDC .

[0071] For example, said battery input current lBatt_est may be calculated by means of the following formula :

[0072] Figure 4 is a diagram 40 showing an exemplary method for obtaining said current generated by aa charging element ICharger •

[0073] Said current generated by a charging element Icharger may be obtained, for example, as a minimum value between :

[0074] - a target current generated by a charging element I Charger_Tgt ;

[0075] - a limitation required by a driver Icharger_Lim_Driver, which may be configured to limit the mmaaxxiimmuumm power received by said charging element; and a limitation due to the charging system, for example a system comprising the charging element, a charging station of which said charging element is a component, or the like, Icharger_Lim_system, related to a maximum current which may be delivered by said charging system.

[0076] Therefore, said current generated by a charging element Icharger may be obtained via a second minimization function M2 applied to the currents described in the foregoing, thus :

[0077] Icharger=min(IC charger _Tgt»‘ Icharger_Lim_Driver> Icharger_Ltm_System) The target current generated by a charging element ICharger_Tgt may be calculated baaed on the strategies Implemented in the charging phase in order to limit the battery input current, for example, as a sum of the target battery input current ICharger_Tgtand of the currents which are absorbed by the high-voltage loads :

[0078] The current absorbed by a DC-DC converter IDCDC may be a current which is measured for example by the DC-DC converter itself, and which may be sent to said battery current estimation block 206. Said current absorbed by a DC-DC converter IDCDC remains constant during the charging phase, and therefore such a current does not require a specific model.

[0079] Normally, the current absorbed by an electric compressor IeAC and the current absorbed by the electric coolant heater IEC may vary during the charging phase of the battery, since they depend on the request of thermal conditioning of the battery, i.e. on said estimate of the battery temperature TBatt_es. The values thereof may be calculated, for example, by means of a battery thermal model block 212.

[0080] A battery model block 210 may be configured to simulate an operation of the battery, for example by modelling one or more battery cells .

[0081] Said battery model block 210 may be configured to receive the time step of the time window block 202 and a voltage value of an amount Vcell_oc from the battery state of charge estimation block 208.

[0082] Said battery model block 210 may be further configured to generate a value of heat rejection of the battery HRBatt and to provide said value of heat rejection of the battery HRBatt to the battery thermal model block 212 and to the battery temperature estimation block 214.

[0083] Figure 6 shows an exemplary model of a battery cell

[0084] 60. A battery cell 60 may be modelled electrically, by using a parallel RC model of the second order.

[0085] Said model of the battery cell 60 comprises a voltage generator Vcell_oc coupled between a first terminal T1 and a second terminal T2. Said coupling of the voltage generator Vcell_oc to said second terminal T2 may be implemented, e.g. , via:

[0086] - a first resistance Ro coupled between said voltage generator Vcell_oc and a first RC stage;

[0087] - the first RC stage, comprising a second resistance Ri and a first capacitor C1, and coupled between said first resistance Ro and a second RC stage; and

[0088] - the second RC stage, comprising a third resistance Ra and a second capacitor Ca, and coupled between said first RC stage and said second terminal Ta. The voltage of the cell Vcell may be considered equal to the voltage difference existing between the first terminal Ti and the second terminal Ta.

[0089] For example, by defining the cell current Icell as the input current into the first terminal T1, it i5 possible to define said cell voltage Vcell by means Of the following equation: wherein Vcell_oc is the voltage difference existing between the first terminal T1 and the second terminal Ta in a condition of open circuit, V1 is the voltage drop on the first RC stage, and V2 is the voltage drop on the second RC stage.

[0090] In other words, the cell voltage Vcell may be calculated as the difference between the voltage Vcell_oc generated by the voltage generator and the voltage drop related to the first parallel RC stage V1, to the second parallel RC stage Va, and to the linear voltage drop due to the presence of the first resistance Ro, obtained via the product of the current flowing In the cell, I cell and said first resistance Ro, i.e. RO - Icell.

[0091] It should be noted that the value of said voltage Vcell_oc which is generated, by means of the battery state of charge estimation block 208, by the voltage generator, may be defined via maps based on the estimate of the state of charge SOCest and on the estimate of the battery temperature TBatt_est.

[0092] The cell current Icell, i.e. the current flowing in the cell 60, may be expressed via the following equation: wherein the value p is the number of cells arranged in parallel which compose the battery.

[0093] It should be noted that the dynamic equations expressed as a function of time V1(t) and V2(t) of the voltage drops related to the first parallel RC stage V1 and to the second parallel RC stage V2, may be expressed via the following equations : wherein the terms R1, R2, C1, and C2 are electrical values characteristic of the battery cell.

[0094] Such electrical values characteristic of the battery cell R1, R2, C1, and C2 may be extracted from maps based on the estimate of the state of charge OCest and on the estimate of the battery temperature TBatt_est.

[0095] By integrating said dynamic equations expressed as a function of time V1(t) and V2 (t) during a simulation of the battery cell, it is possible to calculate the values of the voltage drop related to the first parallel RC stage V1 and of the voltage drop related to the second parallel RC stage V2, respectively.

[0096] The voltage of the battery VBatt may be calculated as a product of the cell voltage Vcell by the number of the series-connected cells s which compose the battery, thus :

[0097] Vbatt = Vcel lS

[0098] The voltage of the battery in a condition of open circuit, i.e. the value of the no-load voltage of the battery, VBatt_oc, may be calculated as a product of the voltage Vcell_oc generated by the voltage generator of a cell 60, i.e. the no-load voltage value of the cell, by the number of the series-connected cells s which compose the battery, thus :

[0099] VBatt_OC = Vcel lS

[0100] The heat rejection of the battery HRBatt may be calculated as the product of the estimate of the battery input current VBatt_oc i.e. of the current flowing within the battery, by the difference between the no-load voltage of the battery VBatt_oc and the voltage of the battery Vbatt, ii..ee.. an estimate of the battery voltage Vbatt_ert, thus :

[0101] HR Batt = IBatt_est * ( VBatt_OC - V Batt)

[0102] The battery thermal model block 212 and the battery temperature estimation block 214 may be configured to operate in a closed loop.

[0103] Figure 5 is a block diagram 50 showing the relations existing between said battery thermal model block 212 and said battery temperature estimation block 214.

[0104] The battery thermal model block 212 may be configured to receive:

[0105] - the target battery input current IBatt_Tgt from said battery limit current block 204,

[0106] - the heat rejection of the battery HRBatt from the battery thermal model block 212, and

[0107] - the estimate of the battery temperature TBatt_est from said battery temperature estimation block 214.

[0108] Said battery thermal model block 212 may be further configured to calculate a thermal power of the battery Oflatt as a function of the received Input values, and to send said thermal power of the battery O ’BMatMt to the battery temperature estimation block 214.

[0109] The battery temperature estimation block 214 may be configured to receive:

[0110] - the time step from the time window block 202,

[0111] - the heat rejection of the battery HHsatt from the battery model block 210, and

[0112] - the thermal power of the battery dpnrf from the battery thermal model block 212.

[0113] Said battery temperature estimation block 214 may be further configured to calculate said estimate of the battery temperature TaattuMt as a function of the input values, and to send said estimate of the battery temperature TaattuMt to the battery thermal model block

[0114] 212, to the battery state of charge estimation block 208, to the battery current estimation block 206, and to the battery limit current block 204.

[0115] Said battery thermal model block 212 comprises one or more models of the strategies for conditioning the battery which are used on a corresponding vehicle having an electric traction motor during the charging phase.

[0116] For example, it is possible to define a lower temperature threshold of the battery Teattjow and an upper temperature threshold of the battery Teettjigh as a function of the driving style which is selected, of a maximum limit of charging power of the battery, and of the state of charge of the battery SOC.

[0117] During the charging phase, tthhee ssttrraatteeggiieess for conditioning the battery may be configured to implement a thermal conditioning of the battery, in such a way as to keep the temperature of said battery Teett In a temperature range between the lower temperature threshold of the battery Teettjew and the upper temperature threshold of the battery Teattjigh .

[0118] When the battery temperature Teatt has a value less than the lower temperature threshold of the battery Teattj-ow, i.e. when Teatt < Teattj-ow, it is necessary to heat the battery.

[0119] On the other hand, when the battery temperature Teatt has a value higher than the upper temperature threshold of the battery Teattjigh, i.e. when Teatt > Teattjigh, it Is necessary to cool the battery. Figure 7 is a graph 70 showing an exemplary behaviour of the battery temperature Teatt during a charging phase of said battery.

[0120] Specifically, said Figure 7 shows the areas wherein the battery is to be heated ('"Battery Heating* in Figure 7) , i.e. wherein the condition Teatt < Teattjew holds, and the areas wherein the battery is to be cooled (Battery Cooling* in Figure 7) , i.e. wherein the condition Teatt > Teattjlgh holds .

[0121] During the heating (Teatt < Teattjew) or the cooling (Teatt > Teattjigh) of the battery it is possible to define a thermal conditioning power.

[0122] Figure 8 Is a diagram 80aof an exemplary method for obtaining the thermal conditioning power provided by the electric coolant heater for heating the battery

[0123] WECHJatt -

[0124] It should be noted that said thermal conditioning power provided by the electric coolant heater for heating the battery der* may be obtained based on a difference between a target heating power and the heat rejection of the battery HRiatt .

[0125] For example, said target heating power may be extracted from a map based on the difference between the lower temperature threshold of the battery Teettjew and the , atimate of the battery temperature Teatt_eat, which is obtained for example by means of a first subtractor block Si, configured to receive, at a first Input terminal, said lower temperature threshold of the battery Teattjow and, at a second input terminal, said estimate of the battery temperature Taatt_e«t, and to provide said difference as output .

[0126] Similarly, said difference between the target heating power and the heat rejection of the battery HRaatt may be obtained by means of a second subtractor block Sa which is configured to receive, at a first input terminal, said target heating power and, at a second input terminal, said heat rejection of the battery HHsatt, and to provide said difference as output .

[0127] In order to obtain said thermal conditioning power for heating the battery der* It Is possible to limit said difference between the target heating power and the heat rejection of the battery HHsatt by means of a maximum thermal power for heating the battery.

[0128] If the electric coolant heater is used both for heating the vehicle cabin and for heating the battery, the maximum thermal power for heating the battery amounts to the difference between a maximum thermal power of the electric coolant heater QecHjJm* which is usually a fixed value, and the thermal power which is already being used for conditioning the vehicle cabin OscHjcabr specifically for heating the vehicle cabin.

[0129] For example, said difference between the maximum thermal power of the electric coolant heater QgcHjJmMd the thermal power used for conditioning the vehicle cabin OscHjcab “ay be obtained by means of a third subtractor block Sa, configured to receive, at a first Input terminal, said maximum thermal power of the electric coolant heater QgcH_ym and, at a second Input terminal, said thermal power for conditioning the vehicle cabin OscHjcabt and to provide said difference as output . Said limitation of the difference between the target thermal power and the heat rejection of the battery HRe*tt by means of the maximum thermal power for heating the battery may be achieved via a third minimization function Ma:

[0130] The thermal power for conditioning the vehicle cabin OscHjcab remains constant throughout the charging phase of the vehicle; therefore, it is not necessary to model said thermal power.

[0131] For example, the value of the thermal power for conditioning the vehicle cabin OscHjcab My be calculated externally of the method described herein, and subsequently it may be sent to said method.

[0132] The current absorbed by the electric coolant heater IKB may be calculated by means of the following equation: wherein TJBCH is the efficiency of the electric coolant heater .

[0133] Figure 9 is a diagram 80b of an exemplary method for obtaining a thermal conditioning power provided by a cooling circuit, which makes use for example of an electric compressor, for cooling the battery d.*C B«*» .

[0134] It should be noted that such thermal conditioning power provided by a cooling circuit which makes use, for example, of an electric compressor for cooling the battery d.*C B«** may be obtained based on a sum between a target cooling power drtflB*ttTfl* and the heat rejection of the battery HRiatt.

[0135] For example, said target cooling power drtflB*ttTfl* may be extracted from a map based on the difference between the estimate of the battery temperature Taatt_e«t and the upper temperature threshold of the battery Teattjigh, which is obtained for example by means of a fourth subtractor block St configured to receive, at a first input terminal, said estimate of the battery temperature Taatt_e«t and, at a second input terminal, said upper temperature threshold of the battery Teettjigh, and to provide the difference as output .

[0136] Similarly, said sum between the target cooling power and the heat rejection of the battery

[0137] HReatt may be obtained by means of a summing block Ss, which is configured to receive, at a first input terminal, said target cooling power OcigBatt Tgt and, at a second input terminal, said heat rejection of the battery HReatt, and to provide said sum as output .

[0138] In order to obtain said thermal conditioning power for cooling the battery d.xr it is possible to limit said sum between the target cooling power OcigBatt Tgt and the heat rejection of the battery HReatt via a maximum thermal power for cooling the battery.

[0139] If one and the same cooling circuit is used both for cooling the vehicle cabin and for cooling the battery, the maximum thermal power for cooling the battery amounts to the difference between a maximum thermal power of the cooling circuit comprising the compressor d.ar t#-.. for example extracted from a map based on a maximum speed of the compressor and on an external temperature, and the thermal power which is already being used for conditioning the vehicle cabin d.xm.*. specifically for cooling the cabin.

[0140] For example, said difference between the maximum thermal power of the cooling circuit comprising the compressor d.xr t#-, and the thermal power used for conditioning the vehicle cabin d.*c_c«i. may be obtained by means of a fifth subtractor block Sc, configured to receive, at a first input terminal, said maximum thermal power of the cooling circuit comprising the compressor and, at a second input terminal, said thermal power for conditioning the vehicle cabin d.xc o.*, and to provide said difference as output .

[0141] Said limitation of the difference between the target cooling power and the heat rejection of the battery HRe*tt by means of the maximum thermal power for cooling the battery may be achieved via a fourth minimization function Me

[0142] The thermal power for conditioning the vehicle cabin d.*c_c«i. remains constant throughout the charging phase of the vehicle; therefore, it is not necessary to model said thermal power.

[0143] For example, the value of the thermal power for conditioning the vehicle cabin d.*c_c«i. may be calculated externally of the method described herein, and subsequently sent to said method.

[0144] The current absorbed by the cooling circuit comprising said electric compressor Ie*c may be calculated by means of the following equation: wherein is the efficiency of the cooling circuit comprising said electric compressor.

[0145] The thermal power of the battery OMM may be calculated by using the following equation:

[0146] Ooatt=OlCH_Batt + HR Batt ~ OeACJatt wherein d.*C B«** has a value other than zero in the conditions of battery cooling, has a value different from zero in the conditions of battery heating.

[0147] The temperature variation of the battery ATa«tt at each time step of the simulation may be obtained as a product of the thermal power of the battery Osatt expected in said time step, i.e. in the current time step, by a duration of said time step Twtndowr for example expressed in seconds (s) , divided by a thermal capacity of the battery Crmoatt, i.e. a characteristic value of the battery, which remains constant :

[0148] Therefore, the estimate of the battery temperature Taatt_e«t at each time step n may be calculated as follows :

[0149] At the beginning of each simulation, the starting value of the expression — 1) may be reset to a starting value TeattuBtart, for example to the value of the actual battery temperature Taattjict .

[0150] Figure 10 is a graph 90ashowing, from a qualitative point of view, an exemplary simulation of the battery temperature Taatt as a function of a simulation time t, which is for example expressed in seconds .

[0151] In figure 10, each of the simulations starts from a respective value of starting temperature TeattuBtart, which may amount to the value of the actual battery temperature Taattju* for the time instant t being considered.

[0152] The reference Taattjnd denotes the respective final temperature vvaalluueess reached by each one of the simulations .

[0153] It should be noted that said final temperature values reached by each one of the simulations Taattjnd depend on the reaching of a target state of charge SOCigt in a simulation of a charging phase of the battery. In fact, such final temperature values reached by each one of the simulations Taatt_xnd correspond to the temperature values reached by the battery at the end of the charging phase, i.e. , when the target state of charge SOCigt is reached.

[0154] Once that the final temperature value Tsatt_xnd associated to a respective current simulation has been reached, i.e. , when the target state of charge SOCigt has been reached, the current simulation ends and a new simulation starts, e.g. from aa respective value of starting temperature Taatt_start.

[0155] The battery state of charge estimation block 208 may be configured to receive:

[0156] - the time step from the time window block 202,

[0157] - the estimate of the battery input current lBatt_e«t from the battery current estimation block 206, and

[0158] - the estimate of the battery temperature Taatt_eat from the battery temperature estimation block 214.

[0159] Said battery state of charge estimation block 208 may be further configured to generate:

[0160] - the voltage value, amounting to a value Vceii_oc, and to provide said voltage value Veeii_oc to the battery model block 210, and

[0161] - the estimate of the state of charge SOCaat of the battery, and to provide said estimate of the state of charge SOCaat to the battery limit current block 204 and to the battery charging time estimation block 216.

[0162] Said battery charging time estimation block 216 may be configured to receive the time step from the time window block 202, and the estimate of the state of charge SOCaat from the battery state of charge estimation block 208, and to calculate an estimate of the charging time of the battery.

[0163] The battery state of charge estimation block 208 may be configured to calculate an increment of the variation of the state of charge ASOCaat for each time step of the simulation.

[0164] Such increment in the variation of the state of charge ASOCaat may be obtained via the product of the estimate of the battery input current Isatt_eat expected for a given time step of a simulation, for example expressed in amperes, and of the duration of said given time step Twtndowf for example expressed in seconds (s) , divided by an electrical capacity of the high-voltage battery Cnectjatt, for example expressed in coulombs and extracted from a map by using an expected average of the temperature of the high-voltage battery:

[0165] Therefore, the estimate of the state of charge SOCaat of the battery at each time step n may be calculated as follows :

[0166] Figure 11 is a graph 90b showing, from a qualitative point of view, an exemplary simulation of the state of charge SOC of the battery as a function of a simulation time t, e.g. expressed in seconds .

[0167] At the beginning of each simulation, the starting value of the expression SOCggt^n — 1) may be set to a starting value SOCstart, for example to the value of the actual state of charge of the battery SOC*ct .

[0168] In Figure 11, each of the simulations starts from a respective value of the starting state of charge

[0169] SOCstart, which may amount to the value of the actual state of charge of the battery SOC*ct obtained at a time instant t being considered.

[0170] It is therefore possible to obtain such increment of the variation of the state of charge ASOCeat by means of the equation described in the foregoing, thus enabling obtaining the estimate of the state of charge SOCaat. It should be noted that such increment of the variation of the state of charge ASOCaat is shown in Figure 11 by the reference SOC me

[0171] Once that the estimate of the state of charge SOCaat related to a current simulation reaches a target state of charge SOCigt, i.e. the state of charge SOC to be reached at the end of the charging phase, the current simulation ends and a new simulation starts, for example from a respective value of the starting state of charge SOCatart •

[0172] Therefore, said battery charging time estimation block 216 may be configured to calculate, for each of the performed simulations, said estimate of the charging time of the battery as the time necessary in each of the simulations to move from the respective value of the starting state of charge SOC start, reset to the value of the actual state of charge of the battery SOCxct, up to the target state of charge SOCigt, ll..ee.. the state of charge SOC to be achieved at the end of the charging phase of the battery.

[0173] Said battery charging time estimation block 216 may be configured to update the estimate of the charging time of the battery after completing each simulation, e.g. by updating a screen visible to the user, for example the visualization device of the infotainment system of the corresponding vehicle.

[0174] Such estimates of the charging time of the battery for each of the simulations are represented in Figure 11 by the references Ti, Ta, Ta, T«, Ta, T«, and T?, which are generally denoted by the reference T±.

[0175] Therefore, solutions as described herein may be applied to vehicles having an electric traction motor and comprising at least one battery, at least one electronic control unit and at least one visualization device, wherein:

[0176] - the at least one electronic control unit Is configured to perform the steps of the method described herein, to generate a signal indicative of a charging time Ti of the at least one battery, and to send said signal indicative of the charging time Ti to the visualization device; and

[0177] - the visualization device, preferably a screen of an infotainment system, is configured to receive the signal indicative of the charging time T± of the at least one battery and to visualize the charging time T± of the at least one battery, for example, so as to inform a user about the time necessary for charging the at least one battery of the corresponding vehicle.

[0178] To sum up, solutions as described herein refer to a method for estimating a charging time T± of at least one battery comprised in a vehicle having an electric traction motor, wherein said method comprises the following operations :

[0179] - determining, e.g. by means of the battery current estimation block 206, a profile of a current absorbed by the at least one battery, l.e. an estimate of the input current of the at least one battery during a charging phase of said at least one battery;

[0180] - determining an actual state of charge SOC*ct (or SOCatart) of the at least one battery;

[0181] - simulating, e.g. by means of the battery state of charge estimation block 208, the charging phase of the at least one battery as a function of the profile of the current absorbed by the at least one battery of the actual state of charge SOC*ct, SOCatart of the at least one battery, of an electrical capacity of the at least one battery Cnectjattr and of a simulation time t, thereby obtaining an estimate of the state of charge SOCeat of the at least one battery; and

[0182] - identifying, for example by means of the block battery charging time estimation 216, as the charging time T± of the at least one battery, a difference between: a first simulation time value t, for example a simulation time amounting to ti, corresponding to an estimate of the state of charge SOCeat of the at least one battery equal to a final state of charge SOCigt of the at least one battery, l.e. wherein said first value of the simulation time ti indicates the moment when. In the simulation, said estimate of the state of charge SOCest reaches the state of final charge SOCigt, and a second simulation time value t, for example a simulation time amounting to ta, corresponding to an estimate of the state of charge SOCeat of the at least one battery equal to the actual state of charge SOCxctr SOCatart of the at least one battery, li..ee., wherein said second value of the simulation time ta indicates the moment when, Iinn tthhee ssiimmuullaattiioonn., said estimate of the charging time SOCert is set equal to the actual state of charge SOC*ct, SOCatart of the at least one battery.

[0183] Therefore, the solution which has been described in detail in the present document enables obtaining a method adapted to estimate the charging time of one or more batteries of a vehicle having an electric traction motor in a more accurate way with respect to the solutions known in the art .

[0184] Without prejudice to the underlying principles, the details and the embodiments may vary, even appreciably, with respect to what has been described herein by way of example only, without departing from the extent of protection .

[0185] The extent of protection is defined by the annexed claims .

Claims

cuing1. Method for estimating a charging time (T±) of at least one battery comprised in a vehicle having an electric traction motor, said method comprising:- determining (206) a profile of a current absorbed by the at least one battery during a charging phase of said at least one battery;- determining an actual state of charge (SOC*ct; SOCatart) of the at least one battery;- simulating (208) said charging phase of the at least one battery as a function of said profile of the current absorbed by the at least one battery (lB*tt_e«t) , of said actual state of charge (SOC*ct; SOCatart) of the at least one battery, of an electrical capacity of the at least one battery (Cnectjatt) r and of a simulation time (t) , obtaining an estimate of the state of charge (SOCaat) of the at least one battery; and- Identifying (216) as charging time (T±) of the at least one battery a difference between a first simulation time value (t; ti) corresponding to an estimate of the state of charge (SOCaat) of the at least one battery equal to a final state of charge (SOCigt) of said at least one battery and a second simulation time value (t; ta) corresponding to an estimate of the state of charge (SOCaat) of the at least one battery equal to said actual state of charge (SOC*ct; SOCatart) of the at least one battery.

2. Method according to claim 1, wherein the operations of determining the actual state of charge (SOC*ct; SOCatart) of the at least one battery, simulating (208) , and Identifying (216) are iteratively repeated until the actual state of charge (SOC*ct) of the at least one battery comprised in said vehicle having an electric traction motor reaches the final state of charge (SOCigt) .

3. Method according to claim 1 or claim 2, whereinsaid operation of simulating (208) comprises :- calculating an estimated increment ooff the state of charge (ASOCeat) , said estimated increment of the state of charge (ASOCeat) being obtained as a function of said simulation time (t) and of a division between said profile of the current absorbed by the at least one battery (Iaatt_e«t) and said electrical capacity of the at least one battery (Cnectjatt) t and- obtaining said estimate of the state of charge (SOCeat) of the at least one battery as a function of said estimated increment of the state of charge (A SOCeat) and of said actual state of charge (SOC*ct; SOCatart) of the at least one battery.

4. Method according to any of the previous claims, wherein said profile of the current absorbed by the at least one battery (lBatt_eat) during the charging phase of said at least one battery is determined (206) as difference between:- a current generated by aa charging element (Icharger) configured to charge said at least one battery comprised in said vehicle having an electric traction motor; and currents absorbed by high voltage loads .

5. Method according to claim 4, wherein current generated by a charging element (Icharger) is determined (206) as a function of :- a first limit current of the charging element (Ichargerjigt) obtained as a function of a current required by the at least one battery (leattjrgt) and of said currents absorbed by the high voltage loads;- a second limit current of the charging element (Icharger_yN_priver) determined using a first driver configured to limit a maximum power received by said charging element; and / or- a third limit current of the charging element(Icharger_yNjByrtee) corresponding to a maximum current that can be delivered by said charging element .

6. Method according to claim 5, wherein said current required by the at least one battery (leattjrgt) is determined (204) as a function of :- a first limit current of the at least one battery (leattjd*) obtained as a function of said estimate of the state of charge (SOCeat) of the at least one battery and of a temperature of said at least one battery (Teett) ;- a second limit current of the at least one battery (Ieett_iae_priver) determined using a second driver configured to preserve a health state of said at least one battery; and / or- a third limit current of the at least one battery (leettjduchrgstrg) configured to minimize a time for performing said charging phase and / or a conditioning phase of said at least one battery.

7. Method according to any of the claims 4 to 6, wherein said currents absorbed by high voltage loads comprises at least one of the following currents :- a current absorbed by an electrical compressor (Ie*c) comprised in said vehicle having an electric traction motor, said current absorbed by the electrical compressor (Ie*c) being obtained as a function ooff a temperature of the at least one battery (Teett) ;- a current absorbed by an electrical coolant heater (leca) comprised in said vehicle having an electric traction motor, said current absorbed by the electrical coolant heater (leca) being obtained as a function of said temperature of the at least one battery (Teett) ; and- a current absorbed by a DC-DC converter (IDCDC) comprised in said vehicle having an electric traction motor, preferably wherein said current absorbed by the DC-DC converter (IDCDC) is measured using said DC-DCconverter .

8. Method according to claim 6 or claim 7, wherein said temperature of the at least one battery (Teett) is estimated (214) :- determining (212) a thermal power of the at least one batterya function of a heat rejection of the at least one battery (HRaatt) ;- determining an actual temperature of the at least one battery (Teettutat; TeettuBtart) ;- simulating (214) said charging phase of the at least one battery as a function of said thermal power of the at least one bbaatttteerryy ((dOssootat)) r• of said actual of the aatt lleeaasstt oonnee battery (TaettUtotf TeettuBtart) t ooff aa tthheerrmmaall ccaappaacciittyy ooff tthhee aatt lleeaasstt one battery ((CCmmmmaatttt)) ,r aanndd ooff ssaaiidd ssiimmuullaattiioonn ttiimmee (t) , obtaining an estimate of a temperature of the at least one battery (Tsatt_e«t) ; and- identifying (214) said temperature of the at least one battery (Teatt) related to a given moment of the charging phase of said at least one battery as the estimate of a temperature of the at least one battery (Taattueat) related to a simulation time (t) corresponding to said given moment .

9. Method according to claim 8, wherein the operations of determining the actual temperature of the at least one battery (Taatt_Act; Taatt_st*rt) r simulating (214) , and identifying (214) are iteratively repeated until the actual state of charge (SOC*ct) of the at least one battery comprised in said vehicle having an electric traction motor reaches the final state of charge (SOCigt) .

10. Method according to claim 8 or claim 9, wherein said operation of simulating (214) comprises :- calculating an estimated increment of the temperature of the at least one battery (ATsatt) r said estimated increment of the temperature of the at leastone battery (ATeett) being obtained as a function of said simulation time (t) and of a division between said thermal power of the at least one battery (dsoa)Md said thermal capacity of the at least one battery (Cmujatt) , and- obtaining said estimate of the temperature of the at least one battery (Tsatt_ert) as a function of said estimated increment of the temperature of the at least one battery (ATaatt) and of said actual temperature of the at least one battery (Tsatt_Act; Taatt_st*rt) .

11. Method according to any of the claims 8 to 10, wherein said thermal power of the at least one battery (Osott) determined as a function of said heat rejection of the at least one battery (HRaatt) is obtained using a thermal model (212) of the at least one battery comprising:- a heating unit of the at least one battery configured to determine a heating thermal power of the at least one battery (darw _— ») ; and- a cooling unit of the at least one battery configured to determine a cooling thermal power of the at least one battery (dcACBott) $ wherein said thermal power of the at least one battery (dihift> is obtained:- summing said heating thermal power of the at least one battery (der* to said heat rejection of the at least one battery (HReatt) , and- subtracting from said sum the cooling thermal power of the at least one battery (dcACBott) •12. Method according to claim 11, wherein said heating thermal power of the at least oonnee battery is determined as a function of :- a first heating thermal power obtained as a function of said temperature of the at least one battery (Teett) ;said heat rejection of the at least one battery(HReatt) $- a second heating thermal power t said second heating thermal power (dar* LM. ) being a maximum thermal power generable by said heating unit of the at least one battery; and- a third heating thermal power (dscHjcae) * said third heating thermal power (dscs_cu) being a thermal power usable for heating a cabin of said vehicle having an electric traction motor.

13. Method according to claim 11 or claim 12, wherein said cooling thermal power of the at least one battery (dcACBott) is determined as a function of :- a first cooling thermal power obtained as a function of said temperature of the at least one battery (Teatt) ;- said heat rejection of the at least one battery(HRaett) $- a second cooling thermal power (d.xr »-.) . said second cooling thermal power (d.ar t#-.) being a maximum thermal power generable by said cooling unit of the at least one battery; and- a third cooling thermal power (da4c_cu) » said third cooling thermal power (d«AC_cu) being a thermal power usable for cooling a cabin of said vehicle having an electric traction motor.

14. Method according to any of the claims 8 to 13, wherein said heat rejection of the at least one battery (HReatt) is obtained as product of said profile of the current absorbed by the at least one battery (lBatt_e«t) and a difference between an open circuit voltage of the at least one battery (Veattuoc) and a voltage of the at least one battery (Veatt) r preferably wherein said open circuit voltage of the at least one battery (Veattuoc) and said voltage of the atleast one battery (VBatt) are obtained using an electrical model of the at least one battery (210) , preferably wherein said electrical model of the at least one battery (210) comprises a parallel RC model of the second order.

15. Vehicle having an electric traction motor and comprising at least one battery, at least one electronic control unit, and at least one visualization device, wherein :- said at least one electronic control unit is configured to perform the steps of the method according to any of the previous claims, to generate a signal Indicative of a charging time (T1) of the at least one battery, and to send said signal Indicative of the charging time (T1) of the at least one battery to said at least one visualization device; and- said at least one visualization device, preferably a screen of an infotainment system, is configured to receive said signal indicative of the charging time (T1) of the at least one battery and to visualize said the charging time (T1) of the at least one battery.

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