A method for managing a thermal power rejected by one or more traction components in a thermal conditioning circuit of a vehicle with an electric powertrain

Abstract

Method for determining a spill flow rate value (ṁT2B, ṁB2T) in a thermal conditioning circuit (TCC) with heat transfer liquid of a vehicle with an electric powertrain, wherein the thermal conditioning circuit (TCC) includes a traction circuit (L_TRC), a cabin circuit (L_CAB), and a battery circuit (L_BAT), the cabin circuit (L_CAB) being connectable in fluid communication with the traction circuit (L_TRC) by means of a first delivery branch and a first return branch, which are configured for the transit of a first spill flow rate (ṁT2C, ṁC2T) coming from and returning to the traction circuit (L_TRC), the battery circuit (L_BAT) being connectable in fluid communication with the traction circuit (L_TRC) by means of a second delivery branch and a second return branch, which are configured for the transit of a second spill flow rate (ṁT2B, ṁB2T) coming from and returning to the traction circuit (L_TRC).

Description

[0001] A method for managing a thermal power rejected by one or more traction components in a thermal conditioning circuit of a vehicle with an electric powertrain

[0002] TEXT OF THE DESCRIPTION

[0003] Field of the Invention

[0004] The present invention refers to thermal conditioning systems of vehicles with an electric powertrain, specifically to circuits with heat transfer liquid. The invention was developed with particular reference to a thermal conditioning circuit with heat transfer liquid which operates in a heat exchange relationship with:

[0005] - one or more traction components, including e. g. an electric traction motor, a corresponding inverter operatively associated therewith, and a corresponding transmission which connects the electric traction motor to at least one corresponding drive wheel,

[0006] - a cabin of the vehicle, specifically for the heating thereof,

[0007] a battery of the powertrain of the vehicle, specifically configured to electrically supply each electric traction motor of the powertrain (also denoted in the following as "high-voltage battery")

[0008] and to the possibility of increasing the energy efficiency thereof.

[0009] Prior Art

[0010] Referring to a thermal conditioning circuit of the type identified in the foregoing, the thermal power which is rej ected by the one or more traction components and which is transferred to the heat transfer liquid circulating in the thermal conditioning circuit is generally reused for heating the high-voltage battery, since the heat transfer liquid being in a heat exchange relationship with the high-voltage battery is the same;however, when the rej ected thermal power exceeds the heating needs of the high-voltage battery, such an excess is simply rej ected to the external environment, particularly by dissipating it by means of a radiator. The consequence is a loss of energy efficiency, since the thermal power which has been rej ected to the external environment is no longer available for possible further uses at the instant when the need arises. As a further consequence, when such a need arises it is necessary to resort to one or more electric heaters (e. g. one upstream of a cabin heater, another one upstream the high-voltage battery) in order to raise the temperature of the heat transfer liquid, with a further consumption of energy -which is electric energy, drawn from the high-voltage battery, with a consequent reduction of the driving range of the vehicle.

[0011] Obj ect of the Invention

[0012] The invention aims at solving the technical problem outlined in the foregoing. Specifically, the object of the invention consists in maximizing the exploitation of the thermal power rejected by the one or more traction components, by preserving the availability thereof even when it is no longer needed, while complying with the thermal conditioning targets and limitations of the thermal conditioning, particularly of the heating, of the cabin and of the battery of the electric powertrain.

[0013] Summary of the Invention

[0014] The object of the invention is achieved by means of a method having the features set forth in the claims that follow, which form an integral part of the technical disclosure provided herein in relation to the invention.

[0015] Brief Description of the Figures

[0016] The invention will now be described with reference to the annexed Figures, which are provided by way of non-limiting example only and wherein:- Figure 1 shows a thermal conditioning circuit wherein it is possible to implement the method according to the invention,

[0017] - Figure 2 is a general block diagram of the method according to the invention,

[0018] - Figures 3 to 6 and 10 to 12 are block diagrams showing various steps and / or deductions of the method according to the invention in a preferred embodiment thereof, and

[0019] - Figures 7 to 9 show time diagrams of values of interest for the method according to the invention, as obtained in the course of simulations.

[0020] Detailed Description

[0021] As a general premise, the Figures annexed to the present description show a method according to the invention, with particular reference to a preferred embodiment, as well as a thermal conditioning circuit (Figure 1 ) wherein it is possible to implement the method according to the invention. However, this is to be construed as merely exemplary, since it is possible to envisage - as will be seen in the following - an implementation of the method in thermal conditioning systems of a different type.

[0022] According to the invention, and with reference to Figure 1, there is defined a method for determining a spill flow rate value in a thermal conditioning circuit TCC with heat transfer liquid of a vehicle with an electric powertrain, wherein the thermal conditioning circuit TCC includes a traction circuit L_TRC, a cabin circuit L_CAB, and a battery circuit L_BAT. The cabin circuit L_CAB is connectable in fluid communication with the traction circuit by means of a first delivery branch and a first return branch configured for the transit of a first spill flow rate ('rhT2Cfor the first delivery branch, 'rhC2Tfor the first return branch) coming fromand returning to the traction circuit. The battery circuit L_BAT is connectable in fluid communication with the traction circuit by means of a second delivery branch and a second return branch configured for the transit of a second spill flow rate ('rhT2Bfor the second delivery branch, mB2Tfor the second return branch) coming from and returning to the traction circuit L_TRC.

[0023] In more detail, referring to the diagram of the circuit TCC in the preferred implementation of the method according to the invention, the first delivery branch extends from a three-way valve VT2C (which is still part of the traction circuit L_TRC) which delivers the first spill flow rate mT2Cto a circuit node T2C (which is already part of the cabin circuit L_CAB), whereas the first return branch extends from a circuit node NC (which is still part of the cabin circuit L_CAB) to a circuit node C2T (which is again part of the traction circuit L_TRC). As regards the battery circuit L_BAT, the second delivery branch extends from a circuit node NT (which is still part of the traction circuit L_TRC) to a circuit node T2B (which is already part of the battery circuit L_BAT), whereas the second return branch extends from a second three-way valve VB2T (which is still part of the battery circuit L_BAT) which delivers the first spill

[0024]

[0025] flow rate to a circuit node B2T (which is again part of the traction circuit L_TRC). The valve VT2C can be controlled in such a way as to implement two circuit configurations, the first corresponding to what is shown in Figure 1, and wherein there is fluid communication among all three ports of the valve, whereas in the second configuration the cabin circuit L_CAB is isolated from the traction circuit and from the battery circuit, i. e. a condition wherein no flow rate transits towards the node T2C.

[0026] Moreover, it should be observed that:- the whole cabin circuit L_CAB is contained between the nodes T2C and NC; specifically, a delivery branch F_CAB and a return branch R_CAB extend therebetween; on the latter there is preferably arranged a one-way valve NR_CAB;

[0027] the whole battery circuit LBAT is contained between the node occupied by the valve VB2T and the node T2B; specifically, a delivery branch F_BAT and a return branch R_BAT extend therebetween;

[0028] - the traction circuit extends between the node occupied by the valve VT2C, the node C2T, the node NT and the node B2T, comprising in particular a delivery branch F_TRC between the node B2T and the valve VT2C, and a return branch which extends in the sections R1_TRC ( from VT2C to C2T), R2_TRC ( from C2T to NT), R3_TRC ( from NT to B2T).

[0029] Each of the valves VT2C and VB2T generally comprises an operating position, wherein two ports out of three are always in fluid communication, in such a way as to ensure the circulation of heat transfer liquid in the traction circuit L_TRC (thus, VT2C always enables a passage of liquid from F_TRC to R1_TRC) and in the battery circuit L_BAT (thus, VB2T always enables a passage of liquid from F_BAT to R_BAT). The respective third port is made traversable in an amount proportional to the amount of the flow rates mB2Tand mT2C.

[0030] Always referring to Figure 1, the traction circuit (L_TRC) includes:

[0031] - at least one traction component TRC (arranged along F_TRC) of said powertrain traversed by a first flow rate of heat transfer liquid mTrcin a first flow direction Fl, wherein the at least one traction component TRC comprises an electric traction motor, an inverter operatively associated with the electric traction motor and a heat exchanger for a transmission lubricant of atransmission connecting each traction motor to one or more corresponding drive wheels of the vehicle,

[0032] - a first circulation pump P_TRC1 (in turn arranged along F_TRC) having a delivery port arranged upstream of the at least one traction component TRC with respect to the first flow direction Fl of the heat transfer liquid, the first circulation pump TP supplying the first flow rate mTrcto the at least one traction component TRC. Preferably, the traction circuit L_TRC comprises a further circulation pump P_TRC2, which is arranged between the nodes C2T and NT, and the delivery whereof is oriented towards the node NT. Moreover, between the nodes C2T and NT there extends a hydraulic parallel arrangement, whereon a radiator RAD is arranged for cooling the one or more traction components. Preferably, moreover, the inlet of the radiator RAD is regulated by means of a valve VT2R, whereas the outlet of the radiator RAD is connected downstream of the valve VT2R, and upstream of or at the node NT.

[0033] Referring to Figure 4, and with the provision of a more detailed description provided in the following, with reference to a vehicle with an electric powertrain and comprising at least one electric traction motor (Figure 4 shows the most general configuration possible, with one electric traction motor for each wheel of the vehicle), the at least one traction component TRC in the traction circuit L_TRC comprises, for each electric traction motor, at least one hydraulic series between the inverter (references INV1, INV2, INV3, INV4 ) operatively associated with the electric traction motor (references Ml, M2, M3, M4 ), the electric traction motor Ml, M2, M3, M4 itself, and a heat exchanger for a transmission lubricant (references WTOC1, WTOC2, WTOC3, WTOC4 ) of a transmission connecting the electric traction motor Ml, M2, M3, M4 to one or morecorresponding drive wheels. With a plurality of electric traction motor, as is the case in Figure 4, the at least one traction component comprises a plurality of hydraulic series connected in parallel with each other.

[0034] Referring again to Figure 1, the cabin circuit L_CAB includes:

[0035] - a cabin heat exchange device CAB_HX, configured to operate in a heat exchange relationship with a cabin air flow rate and traversed by a second flow rate mCabof heat transfer liquid in a second flow direction F2, and, optionally but preferably:

[0036] - an electric cabin heater ECHcab arranged upstream of the cabin heat exchange device (CAB_HX) with respect to the second flow direction F2,

[0037] - a second circulation pump P_CAB having a delivery port arranged upstream of the electric cabin heater ECHcab with respect to the second flow direction F2 of the heat transfer liquid, wherein the second circulation pump P_CAB supplies the second flow rate mCabto the electric heater ECH and to the second heat exchange device CAB_HX.

[0038] Still referring to Figure 1, the battery circuit L_BAT includes:

[0039] - a battery heat exchange device BAT_HX configured to operate in a heat exchange relationship with a battery for the power supply of one or more electric traction motors of the powertrain (or high-voltage battery), wherein the battery heat exchange device BAT_HX is traversed by a third flow rate rii-Bat of heat transfer liquid in a third flow direction F3,

[0040] and preferably

[0041] - a chiller CHL for cooling the flow rate mBatof heat transfer liquid, arranged upstream of the heat exchange device BAT_HX with respect to the third flow direction F3,

[0042] and optionally, but preferablyan electric battery heater ECHBat arranged upstream of the battery heat exchange device BAT_HX with respect to the third flow direction F3, in parallel with respect to the chiller CHL,

[0043] - a third circulation pump P_BAT having a delivery port arranged upstream of the electric heater ECH with respect to the third flow direction F2, wherein the third circulation pump P_BAT supplies the third flow rate mBatto the electric heater ECH and to the battery heat exchange device BAT_HX.

[0044] If only one electric heater is present, it corresponds to the electric cabin heater ECHca.

[0045] Along the circuit TCC there are moreover arranged various temperature sensors, which are configured to detect the temperatures at the inlet and at the outlet of the components which are present in the circuit (these are data of interest for the method according to the invention), and specifically:

[0046] - a first temperature sensor TS1, configured to detect a temperature T1of the heat transfer liquid at the inlet of the device CAB_HX,

[0047] - a second temperature sensor TS2, configured to detect a temperature T2of the heat transfer liquid at the inlet of the device BAT_HX,

[0048] - a third temperature sensor TS3, configured to detect a temperature T3of the heat transfer liquid at the outlet of the device BAT_HX,

[0049] - a fourth temperature sensor TS4, configured to detect a temperature T4of the heat transfer liquid at the outlet of the one or more traction components TRC, - a fifth temperature sensor TS5, configured to detect a temperature T5of the heat transfer liquid at the node NT, i. e. at the second delivery branch,

[0050] - a sixth temperature sensor TS6, configured to detect a temperature T6of the heat transfer liquid atthe outlet of the device CAB_HX,

[0051] - a seventh temperature sensor TS7, configured to detect a temperature T7of the heat transfer liquid at the inlet of the one or more traction components TRC, - an eighth temperature sensor TS_ECHcab, configured to detect a temperature TInECH^ of the heat transfer liquid at the inlet of the electric heater ECHcab (if it is present; it is generally present),

[0052] - a ninth temperature sensor TS_ECHBat, configured to detect a temperature TInECHat the inlet of the electric heater ECHBat(if present).

[0053] This being said with reference to the circuit TCC, according to the invention the method includes determining a target value ṁB2Tof the second spill flow rate ṁT2B, ṁB2Tas a combination of a first value of the second spill flow rate ṁB2Tdetermined by means of a feedforward control, and a second value of the second spill flow rate ṁB2Tdetermined by means of a closed-loop control, wherein determining the first value of the second spill flow rate ṁB2Tcomprises:

[0054] - determining a sufficient value ṁB2Tof the second spill flow rate as a function of a target value ṁBatof the third flow rate of heat transfer liquid, as a function of a temperature T5of the second spill flow rate ṁT2Bin the second delivery branch to the battery circuit L_BAT, as a function of a target value T2of a temperature of the third flow rate ṁBatof heat transfer liquid to an inlet of the battery heat exchange device BAT_HX, and as a function of a temperature T3of the third flow rate ṁBatof heat transfer liquid to an outlet of the battery heat exchange device BAT_HX,

[0055] - determining a maximum value of the second spill flow rate ṁB2Tas a function of the target value ṁBatof the third flow rate of heat transfer liquid, as a function of the temperature T5of the second spill flowrate ṁT2Bin the second delivery branch towards the battery circuit L_BAT, as a function of a maximum permissible value T2of the temperature of the third flow rate ṁBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX, and as a function of the temperature T3of the third flow rate ṁBatof heat transfer liquid at the outlet of the battery heat exchange device BAT_HX,

[0056] - determining a reserve value of the second spill flow rate ṁB2Tas a function of a maximum permissible value ṁTrcof the first flow rate ṁTrcof heat transfer liquid (ṁTrcis to be construed as the maximum permissible value of the flow rate ṁTrc, as a function of the needs of the one or more traction components), as a function of the temperature T5of the second spill flow rate ṁT2Bin the delivery branch to the battery circuit L_BAT, as a function of a minimum permissible value T7of the temperature of the first flow rate ṁTrcof heat transfer liquid at an inlet of the at least one traction component TRC, and as a function of the temperature T3of the third flow rate ṁBatof heat transfer liquid at the outlet of the battery heat exchange device BAT_HX, wherein the minimum permissible value T7of the temperature of the first flow rate ṁTrcof heat transfer liquid at one inlet of the at least one traction component TRC is a function of a minimum permissible value T4of the temperature of the first flow rate ṁTrcof heat transfer liquid at one outlet of the at least one traction component TRC, and wherein the minimum permissible value T4of the temperature of the first flow rate ṁTrcof heat transfer liquid at the outlet of the at least one traction component TRC is a function of a target value

[0057]

[0058] (and, if appliable, ΔTPush) of the temperature of the second flow rate ṁCabof heat transfer liquid at the inlet of the cabin heat exchange deviceCAB_HX,

[0059] - determining the first value of the second spill flow rate in raw form (value 'rhB2Tcc. as the greater of '■''Raw

[0060] the sufficient value 'riiB2TSUff of the second spill flow rate and the lower of said reserve value of the second spill flow rate 'rhB2TCeXLI L and the maximum value of the second spill flow rate 'rhB2Tli / Iif there is an indication of the possibility of requesting the first spill flow rate mT2C,mC2Tby the cabin circuit L_CAB, or as the greater 22 between the sufficient value of the second spill flow rate fnB2TSUff and the maximum value of the second spill flow rate 'rhB2Tli / Iif there is no indication of the possibility of requesting the first spill flow rate mT2C,mC2Tby the cabin circuit L_CAB. As regards the indication of the possibility of requesting the first spill flow rate mT2C,mC2Tby the cabin circuit L_CAB, it essentially corresponds to the possibility of exploiting the heat rej ected by the one or more traction components to heat the heat transfer liquid in the cabin circuit L_CAB, based on a prediction of the possibility of using said heat during the mission, before the conclusion of the latter. If the spill flow rate mT2C, mC2Tis greater than zero, it is inferred that the heat is already being used, whereas, if the flow rate at the beginning of the mission is zero, the prediction of a future use may in any case activate the possibility of heat recovery, which will be confirmed as soon as the flow rate acquires positive values;

[0061] - calculating the value of the second spill flow rate IB2TFFdetermined by feedforward control as the greater of a zero value and the lower of the target value of the third flow rate 'rhBatTgtof heat transfer liquid, the maximum value

[0062]

[0063] of the first flow rate mTrcof heat transfer liquid, the maximum value of the second spill flow rate iB2TMax, and a value of the second spillflow rate comprising at least the value in raw form (raw value)

[0064]

[0065] mB2Tcc,

[0066] - calculating the second value of the second spill flow rate 'riiB2TCLdetermined by means of a closed-loop control as a function of an error depending at least on the temperature T4of the first flow rate mTrcof heat transfer liquid at the outlet of the at least one traction component TRC, on the minimum permissible value T4Minof the temperature of the first flow rate mTrcof heat transfer liquid at the outlet of the at least one traction component TRC, on the temperature T2of the third flow rate mBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX, on the maximum permissible value T2Maxof the temperature of the third flow rate mBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX, and on the target value T2rgtof the temperature of the third flow rate 'rhBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX.

[0067] All the method steps and the related deductions will be described in the following with reference to Figures 2 to 12.

[0068] Referring to Figure 2, diagram 1, it shows a general diagram of the method according to the invention, wherein it is possible to see that the target value of the second spill flow rate is determined as the greater (block 2, MAX) between a zero value (block 4 ) and the lower (block 6, MIN) of:

[0069] - a combination, specifically a sum (block 8 ) of the values mB2TpFand mB2TcL

[0070] - the target value ThBatTgtof the third flow rate mBat°f heat transfer liquid,

[0071] - a maximum value rii-TrcMax°t he first flow rate mTrcof heat transfer liquid, and

[0072] - the maximum value of the second spill flow rate™B2TMa%•

[0073]

[0074] As regards the values ihB2Tsuff, mB2TMax, mB2TExtHton which the calculation of the value riiB2TpFis based, they may be defined as follows:

[0075] i) riiB2Tsuffis a value of the second spill flow rate sufficient to meet a target temperature value T2Tgtat the inlet of the battery heat exchange device BAT_HX, ii)

[0076]

[0077] is a maximum permissible value of the second spill flow rate, and specifically a value of spill flow rate which leads to a maximum permissible temperature T2Maxat the inlet of the battery heat exchange device BAT_HX, specifically a temperature beyond which a thermal shock of the high-voltage battery would occur,

[0078]

[0079] iii) is a reserve value concerning the device BAT_HX, and specifically indicates a value of the second spill flow rate which can in any case be destined to the high-voltage battery (thus to the device BAT_HX) even in the presence of a request of first spill flow rate to the cabin circuit L_CAB. In other words, it is a value of the second spill flow rate which in any case ensures a minimum temperature value T7Minat the inlet of the one or more traction components TRC, thus a minimum temperature value of the heat transfer liquid returning from the battery circuit L_BAT to the traction circuit L_TRC which - consequently - always ensures a target temperature value at the inlet of the heat exchange device CAB_HX.

[0080] The value '^B2TSUff may be determined by writing equations of mixing at the nodes, and particularly the continuity equation at the node T2B:

[0081] ^B2TSuff■ T5+ (mBatTgt- mB2Tsuff^ ■ T3= mBatTgt■ T2rgt

[0082]

[0083] hence_T2TgtT3

[0084] mB2TSuff~ ‘mBatTgt

[0085]

[0086] The expression uses the value T2Tgtbased on the definition of ThB2Tsuff.

[0087] Similarly, and always referring to the equations of mixing at the nodes, and particularly to the continuity equation at the node T2B, for the flow rate 'rhB2Tiliv / lICiX it is possible to write:

[0088] • _ T£. Max _ ~ T-3 _ •

[0089] mB2TMax~ ~ T3mSatTgt

[0090]

[0091] by simply replacing T2rgtwith T2Max.

[0092] On the other hand, always referring to the equations of mixing at the nodes, and particularly to the continuity equation at the node B2T, for the flow rate mB2Tc. it is possible to write:

[0093] ■ T3+ (mTrc- mB2TT5- mTrCMax■ T7 Min

[0094] hence:

[0095] ~T? Min ■mB2TExtHt~ T5~ T3mTrcMax

[0096]

[0097] Again, it is possible to observe that the expression uses the value T7„. based on the definition of mB2Tc, As regards the temperature T7Min, it is connected to the temperatures T4of the heat transfer liquid at the outlet of the one or more traction components TRC, and 7 at the inlet of the cabin heat exchange device CAB_HX. In detail, since the temperature T7Minis a minimum value of return of the second spill flow rate mB2Tto the traction circuit L_TRC, the consequent temperature atthe outlet of the at least one traction component TRC is in turn a minimum value T4n,.; thus, it is a value sufficient to ensure a target temperature value T1Tgtat the inlet of the cabin heat exchange device CAB_HX, which corresponds to a target value sufficient to meet the request for heating thermal power of the device CAB_HX. The target value Tlrgtmay be taken into consideration in itself, without corrections, or else - more preferably, especially when the heater ECHcab is present - the target temperature value at the inlet of the device CAB_HX is defined as the sum Tlrgt+ TPushcab, wherein TPushcabis a temperature reserve, specifically a positive increase, which is used as a calibration amount, i. e. a temperature reserve which enables, during calibration, to minimize the consumption of electric power by the heater ECHcab.

[0098] Referring to Figure 3, diagram 10, whatever the form of the target temperature value Tl fi. e. either T1Tgtor ^Tgt+^TPUShCab(block 12 ), the determination of the temperature T7Minis preferably operated with reference to a stationary thermal calculation model 14 of the heat transfer liquid through the at least one traction component, thereby enabling to express T7Minas a function of T4„., and thus obtaining the value of mP2Tc. (block 16).

[0099] Referring to Figure 4, considering the most general configuration of electric powertrain, thus a four-motor configuration including four electric traction motors Ml, M2, M3, M4, each being operatively associated with a respective inverter INV1 (motor Ml ), INV2 (motor M2 ), INV3 (motor M3), INV4 (motor M4 ), and each being operatively associated with a respective heat exchanger for a transmission lubricant WTOC1 (motor Ml ), WTOC2 (motor M2 ), WTOC3 (motor M3), WTOC4 (motor M4 ), wherein each heat exchanger receives and dissipates the thermal power rej ected by the transmission lubricant, by meansof which the respective electric traction motor transmits motion to the corresponding drive wheel. As can be schematically seen in Figure 4, for each electric traction motor the heat transfer liquid circulates in a hydraulic series of inverter - electric traction motor - heat exchanger for transmission lubricant, in this order. Each series INV1-M1-WT0C1, INV2-M2-WTOC2, INV3-M3-WTOC3, INV4-M4-WTOC4 is hydraulically connected in parallel to the other series, in such a way that the temperature of the heat transfer liquid at the inlet of the parallel arrangement of the hydraulic series is the temperature T7(thus, at its minimum value, T7Min), and the temperature of the heat transfer liquid at the outlet of the parallel arrangement of the hydraulic series is the temperature T4(thus, at its minimum value, T4Min).

[0100] Assuming the presence of stationary conditions, there is no increase of internal energy of each volume of heat transfer liquid, and therefore the temperature of the heat transfer liquid between two subsequent components of each hydraulic series remains constant.

[0101] Such temperatures, which are all shown in Figure 4, include:

[0102] ToutInV1‘ the temperature of the heat transfer liquid leaving the inverter INV1 ( from a cooling j acket thereof ), i. e. in a volume of heat transfer liquid located between the outlet of the inverter INV1 and the inlet of the motor Ml (of a a cooling j acket thereof ),ToutMotl:the temperature of the heat transfer liquid leaving the motor Ml ( leaving a cooling j acket thereof ), i. e. in a volume of heat transfer liquid located between the outlet of the motor Ml and the inlet of the heat exchanger WTOC1,

[0103] ToutoiiExl‘ the temperature of the heat transfer liquid leaving the heat exchanger WTOC1, i. e. in a volume of heat transfer liquid located between the outlet of theheat exchanger WT0C1 and the outlet of the parallel arrangement of the hydraulic series,

[0104] TOut / ni?2: the temperature of the heat trans fer liquid leaving the inverter INV2 ( leaving a cooling j acket thereof ), i. e. in a volume of heat trans fer liquid located between the outlet of the inverter INV2 and the inlet of the motor M2 ( of a cooling j acket thereof ), TOutMot2: the temperature of the heat trans fer liquid leaving the motor M2 ( leaving a cooling j acket thereof, i. e. in a volume of heat trans fer liquid located between the outlet of the motor M2 and the inlet of the heat exchanger WTOC2,

[0105] ^outoiiEX2:the temperature of the heat trans fer liquid leaving the heat exchanger WTOC2, i. e. in a volume of heat trans fer liquid located between the outlet of the heat exchanger WTOC2 and the outlet of the parallel arrangement of the hydraulic series,

[0106] TOut[nv3: the temperature of the heat trans fer liquid leaving the inverter INV3 ( leaving a cooling j acket thereof ), i. e. in a volume of heat trans fer liquid located between the outlet of the inverter INV3 and the inlet of the motor M3 ( of a cooling j acket thereof ), ToutMot3:the temperature of the heat trans fer liquid leaving the motor M3 ( leaving a cooling j acket thereof ), i. e. in a volume of heat trans fer liquid located between the outlet of the motor M3 and the inlet of the heat exchanger WTOC3,

[0107] ToutoiiEX3‘ the temperature of the heat trans fer liquid leaving the heat exchanger WTOC3, i. e. in a volume of heat trans fer liquid located between the outlet of the heat exchanger WTOC3 and the outlet of the parallel arrangement of the hydraulic series,

[0108] TOut[nv^: the temperature of the heat trans fer liquid leaving the inverter INV4 ( leaving a cooling j acket thereof ), i. e. in a volume of heat trans fer liquidlocated between the outlet of the inverter INV4 and the inlet of the motor M4 (of a cooling j acket thereof ), ToutMot4’ he temperature of the heat transfer liquid leaving the motor M4 ( leaving a cooling j acket thereof ), i. e. in a volume of heat transfer liquid located between the outlet of the motor M4 and the inlet of the heat exchanger WTOC4,

[0109] ToutoiiEX4‘ the temperature of the heat transfer liquid leaving the heat exchanger WTOC4, i. e. in a volume of heat transfer liquid located between the outlet of the heat exchanger WTOC4 and the outlet of the parallel arrangement of the hydraulic series.

[0110] As a consequence, the thermal evolution of the heat transfer liquid may be described as an increase, in stationary conditions, of the temperature of the heat transfer liquid from the inlet to the outlet of a traction component.

[0111] Generally speaking, it is possible to write, with respect to the at least one traction component TRC and for each traction component, the general formula of the Fourier equation

[0112] 1

[0113] p ' (Temp ~ 7 / n)—™Clnt ' ^Pcint ' (T Out Tin)

[0114] thcmp wherein:

[0115]

[0116] Rthcmp isthe thermal resistance between the component and the heat transfer liquid, which may be estimated by means of experimental tests,

[0117] Temp isthe current temperature of the traction component (motor, inverter, transmission lubricant in the heat exchanger), measured by a corresponding sensor (or by corresponding sensors),

[0118] TInis the temperature of the heat transfer liquid at the inlet of the traction component,TOutis the temperature of the heat transfer liquid at the outlet of the traction component,

[0119] cPcint is the specific heat at constant pressure of the heat transfer liquid, calculated at an average temperature between the inlet and the outlet (of the traction component),

[0120] Want is the mass flow rate of the heat transfer liquid through the traction component.

[0121] It is therefore possible to define a system of equations concerning the heat balance across each traction component in the circuit L_TRC, considering, as flow direction F2, the direction shown in Figure 4, and moreover adding an equation of mixing at the outlet of the parallel arrangement of hydraulic series (the thirteen unknown values are highlighted by being underlined the first time they appear in the system - and the first time only, thus the following occurrences of the same unknown value are not highlighted)

[0122] 1 (rr _ (1) p ' I TQUEX-. TOutMot^ 1 — hl7’rCir - I T — T Pclnt I OutoilEx-L thoilEx-L ' - '1 / \ > (2)—^Out / np I—TYlTrc-L Cpclnt \FoutMoti ToutinV1) ^th-Mot! ' - ' n—T7Min) = mTrCiCpclnt ^Toutinvi Min)

[0123] (4) ' \ ToilEx2ToutMot2)—™Trc2■ r - I T — T Pclnt I OutoilEX2 OutMot2tflOilEx2' - ' (5) — \ TMot2— TOut1 — mTrC2Cpclnt \^OutMot2 ^OutinV2) (6) „ (rInV2— T7Min} = mTrC2Cpclnt ^^0utinv2 Min) thlnvz (7) — \ ToilEx3~ ToutMot3) ~ W-Trcs ■ r - I T — T Pclnt I OutoilEx3OutMot^ thoilEx3V-71 / \. (8) p (TMot3~TOutinv) - ^Trcs Cpclnt yfoutMots Toutinvz

[0124]

[0125] KihMot3V-17(9) R ' ^lnv?- Min) ~ ^Trcs ^Pclnt \ 'outinV3J thlnvz 1 ( \ _ (10) \ ToilEx4~ ToutMot4] — ^Trc4• r ■ I T — T '"'Pclnt \1 0ut0ilEX41 Ou^Mot4tfl0ilEx4' ' (11) p I TMot4~ TOut1 — mTrCiCpclnt ^0utinV4KthM0t4' - ' (12) T (TInv4~R7Min)=W-Trc^ Cpcint (^0utinV4^^Min^) thrnv4(13) mTrc■ l\Min— mTrCi■ T0utoilEx^ + mTrC2■ T0utoilEx^ + mTrCs■ ToutoilEXs+ ™-Trc4

[0126] ■ T

[0127]

[0128] 0utOilEx4

[0129] wherein:

[0130] ritTrC1, ^Trcz ' Trc3>1^lTrc4are fixed fractions of the flow rate mTrcMax ' and they correspond to the mass flow rate of heat transfer liquid flowing in each hydraulic series (the index 1, 2, 3, 4 is associated with the hydraulic series, and therefore - by way of example - mTrCiis the flow rate flowing in the series INV1-M1-WTOC1 ).cPcint is thespecific heat at constant pressure of the heat transfer liquid, calculated at an average temperature between T4„. and T7„., wherein 71. is

[0131]

[0132] the temperature T7Mincalculated at the previous step time, and initialized to the value T4Min. In other words,cPcint is preferably calculated by means of a map which uses, as input data item, a temperature T calculated as: T = (T4... + T7„. } / 2, wherein T7^. is initialized to the

[0133]

[0134]

[0135] value T4M.n.

[0136] RthMot.,RthInv.,RtnoilEx. are, respectively, the thermal resistances of the i-th electric traction motor (RthMot. r i = 1, 2, 3, 4 ), of the i-th inverter ( Rthlnv, i = 1, 2, 3, 4 ), and of the i-th heat exchanger for transmission lubricant (RthoilEx. > i = 1, 2, 3, 4 ).

[0137] By solving the system of thirteen equations ( 1 ) - ( 13) provided in the foregoing, it is possible to express the temperature value T7„. as a function of T4„.. It is therefore possible to calculate the value sothat the three values of the second spill flow rate mDR‘2-n‘ Suff ‘ biDp‘2-T‘ Max and mDR‘2-T‘ Ec.xtHt used for the feedforward

[0138]

[0139] control are known.

[0140] With reference to Figure 5, diagram 20, it schematically shows the calculation of the raw valuer^lB2Tccf which depends on the presence or absence of an ‘‘‘‘Raw

[0141] indication of the possibility of requesting the first spill flow rate mT2C,mC2Tby the cabin circuit L_CAB. Said indication of possibility is represented by a state variable CabRecoverypred, which acquires the logic state "0" (FALSE) if there is no indication of the possibility of requesting the first spill flow rate mT2C,mC2Tby the cabin circuit L_CAB, and the logic state "1" (TRUE) when there is an indication of the possibility of requesting the first spill flow rate mT2C,mC2Tby the cabin circuit L_CAB. The logic state of the variable CabRecoverypredis determined by control logics external to the method according to the invention, typically control logic pertaining to the management of the thermal conditioning of the cabin of the vehicle (they are generally predictive logics, which detect the thermal state of all thermal components of the vehicle throughout the duration of the mission, and which define whether it is convenient to use the heat rej ected by the one or more traction components to reduce the energy consumption of the cabin heater ECHca or to make the battery more efficient), but the general meaning of the variable CabRecoverypredconcerns the priority of the thermal conditioning (heating) targets of the cabin over the thermal conditioning (heating) targets of the battery. In the diagram of Figure 5, this is exemplified by a switch SW20 (the variable CabRecoveryPredwhereof defines a control variable C20) which outputs – i.e. inputs into the block 22 – the value associated with the route "T" when CabRecoveryPred= 1, whereas it outputs the valueassociated with the route " F" when CabRecoverypred= 0.

[0142] In this regard, the value ṁB2Tis determined as the greater (block 22, MAX) of the sufficient value ṁB2Tof the second spill flow rate and the lower (block 24, MIN) of the reserve value of the second spill flow rate ṁB2T, and the maximum value of the second spill flow rate

[0143]

[0144] if there is an indication of the possibility of requesting the first spill flow rate mT2c> TTT-C2T by the cabin circuit L_CAB (CabRecoverypred= 1), or as the greater between the sufficient value of the second spill flow rate ṁB2Tand the maximum value of the second spill flow rate ṁB2Tif there is no indication of the possibility of requesting the first spill flow rate mT2C,mC2Tby the cabin circuit L_CAB ( CabRecoverypred= 0).

[0145] In other words, if there is an indication of the possibility of requesting the first spill flow rate mT2C,mC2Tby the cabin circuit L_CAB to meet thermal conditioning (heating) needs of the cabin, then said request is prioritized, and the flow rate biB2Tccis ‘‘‘‘Raw superiorly limited by the reserve value biB2TCl, (which is generally lower than ṁB2T), whereas the lower limit is ṁB2T, i. e. a value which is at most sufficient to meet the temperature target of the heat transfer liquid at the inlet of the device BAT_HX, but not more than that. On the contrary, if there is no indication of the possibility of requesting the first spill flow rate mT2c> TTT-C2T by the cabin circuit L_CAB (CabRecoverypred= 0), all the spill flow rate may be directed towards the battery, with the upper limited being raised to the value ṁB2T, which on a logical level exceeds the minimum block 24.

[0146] If the battery circuit L_BAT comprises the electric battery heater ECHe t, advantageously, an additional term ṁB2Tof the first value of the second spill flow rateṁB2Tis defined as a function of an electric power to be supplied to the electric battery heater ECHBat, and as a function of the temperatures T5, T3.

[0147] In detail, the additional term ṁB2Thas the

[0148]

[0149] purpose of increasing the second spill flow rate in favour of the battery when an active heating of the same battery is requested, and when the electric heater ECHBat is turned on. The additional term ṁB2Thas the

[0150]

[0151] function of compensating an instantaneous electric power PwrECHabsorbed by the heater ECHBat, in such a way as to allow for turning off the electric heater also during the active heating of the battery. In terms of enthalpy, and assuming that the electric power PwrECHBatis wholly converted into thermal power, it is possible to write:

[0152] ^

[0153]

[0154] B2TFFAdd■ Cpclnt■ (T5- T3~) = PwrECHBat

[0155] hence:

[0156] ṁB2T= PwrECH / (cp· (T5− T3))

[0157] wherein cpis the specific heat at constant pressure of the heat transfer liquid, calculated at an average temperature between T5and T3, and wherein T5— T3represents the total thermal gradient of the second spill flow rate from the inlet of the battery circuit L_BAT to the outlet of the heat exchange device BAT_HX.

[0158] Referring to Figure 6, diagram 30, it is therefore possible to calculate the value of the second spill flow rate ṁB2Tdetermined by feedforward control as the greater (block 32, MAX) of a zero value (block 34 ) and the lower (block 36, MIN) of the target value ṁBatof the third flow rate of heat transfer liquid ṁBat, a maximum value ṁTrcof the first flow rate ṁTrcof heattransfer liquid, the maximum value riiB2TMaxof the second spill flow rate, and a sum (block 38 ) of the values ^B27’cc- and

[0159]

[0160] 7iiR27’E-E- (if the latter is calculated). In other words, the value ṁB2Tis superiorly limited by the strictest of the values ṁBat, ṁB2Tand ṁTrc, and inferiorly limited by the zero value, in such a way as to exclude the possibility of negative flow rate values.

[0161] The following Figures 7 to 9 show time diagrams relating to the simulation of the evolution of some values of interest concerning the feedforward control. Figure 7 comprises four diagrams 7A, 7B, 7C, 7D, which are synchronized in time and wherein:

[0162] the diagram 7A shows the evolution of the temperatures T2, T2Max, T2rgt,

[0163] the diagram 7B shows the evolution of the temperatures T3, T5,

[0164] - the diagram 7C shows the evolution of the flow rates of the type mB2T, including mB2TMax, mB2Tpp, mB2Tsuff, - the diagram 7D shows the evolution of the electric power PwrECHBat.

[0165] The results of the simulations as per the diagrams 7A-7D show that, as soon as the temperature T5exceeds the temperature T3by a given threshold (instant t1, diagram 7B), the flow rate ṁB2Tacquires the highest value possible (ṁB2T) consented by the physical limitations (upper saturation, diagram 7C). When the current temperature of the heat transfer liquid at the inlet of the device BAT_HX (temperature T2, instant t2) reaches the target value T2Tgtand the power PwrECHabsorbed by the heater ECHBatdecreases (instant t3, diagram 7D), in the same way as ṁB2T, the flow rate ṁB2Tdetermined by feedforward control keeps on following ṁB2T. As a consequence, in the case of battery heating only, the evolution of T2distinctlyseparates from T2rgtand converges towards T2Max.

[0166] If only a cabin heating is requested and CabRecoveryPred= 1 holds true,

[0167]

[0168] is limited by the value of T7Min, which depends on the target temperature at the inlet of the heat exchanger CAB_HX. In this scenario, the possible heat in excess rej ected by the one or more traction components TRC, which is not necessary for the cabin heating, is absorbed by the battery, thereby improving the efficiency thereof.

[0169] Figure 8 comprises three diagrams 8A, 8B, 8C which are synchronized in time and wherein:

[0170] the diagram 8A shows the evolution of the temperatures T2, T2Max, T2rgt,

[0171] the diagram 8B shows the evolution of the temperatures T4, T4,

[0172] - the diagram 8C shows the evolution of the flow rates of the type ṁB2T, including ṁB2T, ṁB2T, ṁB2T.

[0173] From the simulations it is possible to observe that, as long as there is no heat in excess rej ected by the one or more traction components TRC, T2follows the target value T2Tgtand the flow rate ṁB2Tdetermined by feedforward control stays at zero. Once that the current temperature T4at the outlet of the one or more traction components TRC exceeds T4by a certain threshold (instant t4), the flow rate ṁB2Tdetermined by feedforward control follows the evolution of ṁB2T, which starts increasing. T2stops following the target value T2rgt, but it always stays below the maximum valueT2Max-when T2 reaches T2Max(instant t5), mB2TMaxbecomes lower than mB2Tc, and the flow rate ṁB2Tdetermined by feedforward control starts following

[0174]

[0175] • This is the case of a passive heating of the battery and an active heating of the cabin, with CabRecoveryPred = 1. In the absence of an active heating of the battery (i. e. in the case of a passive heating), the temperature T2Tgtremains equal to the current temperature of the battery. In the case of a combined heating, and with CabRecoverypred= 1, it is assumed that the flow rate riiB2TpFdetermined by feedforward control follows biB2Tsuff. However, when the current temperature of the heat transfer liquid at the inlet of the device BAT_HX approaches the target value T2Tgtr the flow rate ThB2Tsuffsignificantly decreases. Moreover, if the one or more traction components rej ect more thermal power than the power being currently used by the heat exchanger CAB_HX or the power potentially stored to be destined thereto, the flow rate ṁB2Tdetermined by feedforward control may instead follow ṁB2T.

[0176] Figure 9 comprises five diagrams 9A, 9B, 9C, 9D, 9E, which are synchronized in time and wherein:

[0177] the diagram 9A shows the evolution of the temperatures T2, T2Max, T2rgt,

[0178] the diagram 9B shows the evolution of the temperatures T3, T5,

[0179] the diagram 9C shows the evolution of the temperatures T4, T4,

[0180] - the diagram 9D shows the evolution of the flow rates of the type mB2T, including mB2TMax, mB2Tpp, mB2Tsuff,

[0181]

[0182] - the diagram 9E shows the evolution of the electric power PwrECHBat.

[0183] The results of the simulation which can be observed in the diagrams 9A-9E (combined heating of the cabin and the battery, with CabRecoveryPred = 1) are similar to the behaviour observed in the scenario of battery heating only, with a remarkable exception:

[0184]

[0185] keeps on following the evolution of ṁB2T, whereas ṁB2Tremains at zero, since T4never exceeds T4. As a consequence, without the availability of additional energy, the second spill flow rate is regulated in sucha way as to supply only the amount which is strictly necessary for heating the battery.

[0186] If CabRecoverypred= 0 holds true, the evolution of ṁB2Tfollows

[0187]

[0188] since there is no advantage in storing energy in expectation of a later reuse of the heat rej ected by the one or more traction components for heating the passenger compartment before the end of the mission (the logical state of CabRecoveryPredis by definition evidence of such a circumstance).

[0189] When the current temperature of the heat transfer liquid at the inlet of the device BAT_HX (temperature T2, instant t6) reaches the target value T2Tgtand the power PwrECHabsorbed by the heater ECHBatdecreases to zero – in the same way as ṁB2T– the flow rate ṁB2Tdetermined by feedforward control follows ṁB2T. As a consequence, the evolution of T2distinctly separates from T2and remains at T2.

[0190] Referring to Figures 10 to 12, there will now be described the preferred modes for determining the value ṁB2T. The closed-loop control is based, in the same way as the feedforward control, on the temperatures of the heat transfer liquid. Specifically, referring to Figure 10, diagram 40, the error ERR as a function whereof a proportional-integral controller 41 operates is determined as the greater (block 42, MAX) of the following:

[0191] - a difference (block 43) between a sum (block 44 ) of the target value T2Tgtof the temperature of the third flow rate mBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX with a temperature reserve TPushBatof the third flow rate mBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX and a current temperature value TInof the third flow rate ṁBatof heat transfer liquid at the inlet of the electric battery heater ECHBat(in the absence of ECHBat, the block 43 would correspond to the difference

[0192]

[0193] T2+ ΔTPush− T2);

[0194] and one of:

[0195] - the lesser (block 45, MIN) of a second difference (46) T4— T4Minbetween the temperature T4of the first flow rate mTrcof heat transfer liquid at the outlet of the at least one traction component TRC and the minimum permissible value T4Minof the temperature of the first flow rate mTrcof heat transfer liquid at the outlet of the at least one traction component TRC, and a third difference T2− T2between the maximum permissible value T2°f the temperature T2of the third flow rate mBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX and of the value T2of the temperature of the third flow rate mBatof heat transfer liquid at the inlet of the battery heat exchange device BAT_HX if there is (CabRecoverypred= 1, control variable C40 for a switch SW40, route " T") an indication of the possibility of requesting the first spill flow rate mT2C,mC2Tby the cabin circuit L_CAB;

[0196] - the third difference (block 47 ) T2Max— T2if there is no (CabRecoverypred= 0, control variable C40 for the switch SW40, route " F") an indication of the possibility of requesting the first spill flow rate mT2C,mC2Tby the cabin circuit L_CAB.

[0197] In other words it is defined, as a function of three temperature errors of the heat transfer liquid, specifically:

[0198] i) a first error El corresponding to the difference T4— T4Min(block 46), which is the error regarding the flow rate mB2Tc,

[0199] ii) a second error E2 corresponding to the difference T2− T2(block 47), which is the error regarding the flow rate ṁB2T;

[0200] iii) a third error E3 corresponding to thedifference (T2+ ΔTPush) − TInresulting from the set of blocks 43, 44, and which corresponds to the error regarding the flow rate ṁB2T. ΔTPushis – in the same way as ΔTPush– a calibration amount which is required for using, as much as possible, the thermal heating power coming from the second spill flow rate, in order to minimize the electric power consumption for the heater ECHBat.

[0201] Always referring to the determination of the error ERR, if the temperature T2is lower than the value T2Maxor if the temperature T2is lower than the target value T2Tincreased by the amount TPushBat, the second spill flow rate to the battery circuit L_BAT may increase. As a consequence, the coefficients Kpand Kiof the controller PI must always be positive or equal to zero for each value of the error signal.

[0202] Referring to the Figures 11 and 12, in order to keep the value ṁB2Twithin predefined limits, there are defined a lower saturation limit PILowerSaturationLimitand an upper saturation limit PIUpperSaturationLimitfor the controller PI. The lower saturation limit is schematically shown in Figure 11, diagram 50, and it is equal to the opposite (block 52, sign reversal) of the value ṁB2Tdetermined by feedforward control. In other words, the closed-loop correction must not be greater than the value calculated by feedforward, in such a way as to avoid negative values of the second spill flow rate.

[0203] The upper saturation limit PIUpperSaturationLimit, Figure 12, diagram 60, is equal to a difference (block 62) between the lower (block 64) of the target value of the third flow rate of heat transfer liquid ṁBat, the maximum value of the second spill flow rate ṁB2Tand the maximum value of the first flow rate of heat transfer liquid ṁTrc, and the value of the second spill flowrate ṁB2Tdetermined by feedforward control. In other words, the upper saturation limit corresponds to the margin available for the closed-loop control with respect to the feedforward control (ṁB2T), superiorly limited by the lowest of the flow rates ṁBat, ṁB2Tand ṁTrc

[0204] Thanks to the method according to the invention, it is therefore possible to achieve an improved battery performance (also as regards the useful life thereof ): this leads to an improved driving range in the long term and to a higher battery reliability. Moreover, the method according to the invention leads to achieving an improved general efficiency, since the consumption of electric energy by the electric heaters (whichever may be present) is minimized, thus obtaining the greatest benefit possible from the thermal power which is available (i. e. free) in the system. Substantially, this enables maximizing the use of the thermal power rej ected by the one or more traction components, by keeping the availability thereof even when it is no longer needed, while respecting the targets and the limitations of the thermal conditioning, particularly the heating, of the cabin and of the battery of the electric powertrain.

[0205] Of course, the implementation details and the embodiments may amply vary with respect to what has been described and illustrated without departing from the extent of the present invention, as defined by the annexed claims.

Claims

CLAIMS1. A method for determining a spill flow rate value (mT2B,mB2T) in a thermal conditioning circuit (TCC) with heat transfer liquid of a vehicle with an electric powertrain, wherein the thermal conditioning circuit (TCC) includes a traction circuit (L_TRC), a cabin circuit (L_CAB), and a battery circuit (L_BAT), the cabin circuit being connected in fluid communication with the traction circuit by means of a first delivery branch and a first return branch configured for the transit of a first spill flow rate (mT2C,mC2T) coming from and returning to the traction circuit, the battery circuit being connectable in fluid communication with the traction circuit by means of a second delivery branch and a second return branch configured for the transit of a second spill flow rate (mT2B,mB2T) coming from and returning to the traction circuit,wherein the traction circuit (L_TRC) includes:- at least one traction component (TRC) of said powertrain traversed by a first flow rate of heat transfer liquid ('rhTrc') in a first flow direction (Fl ), said at least one traction component (TRC) comprising an electric traction motor (Ml, M2, M3, M4 ), an inverter ( INV1, INV2, INV3, INV4 ) operatively associated with the electric traction motor and a heat exchanger for a transmission lubricant (WTOC1_WTOC2, WTOC3. WTOC4 ) of a transmission connecting each electric traction motor to one or more corresponding drive wheels of the vehicle, a first circulation pump (P_TRC1 ) having a delivery port upstream of said at least one traction component (TRC) with respect to the first flow direction (Fl ) of said heat transfer liquid, the first circulation pump (TP) supplying said first flow rate mTrc) to the at least one traction component (TRC),where the cabin circuit (L_CAB) includes:- a cabin heat exchange device (CAB_HX) configured to operate in a heat exchange relationship with a cabin air flow and traversed by a second flow rate ('rhcab ') of heat transfer liquid in a second flow direction (F2 ), where the battery circuit (L_BAT) includes:a battery heat exchange device (BAT_HX) configured to operate in a heat exchange relationship with a battery for the power supply of one or more electric traction motors of the powertrain, the battery heat exchange device (BAT_HX) being traversed by a third flow rate mBat) of heat transfer liquid in a third flow direction ( F3 ),the method including determining a target value mB2T1 QZ ) of the second spill flow rate (mT2B, mB2T) as a combination of a first value of the second spill flow rate (mB27>F) determined by feedforward control, and a second value of the second spill flow rate (mB2TCL) determined by closed-loop control, wherein determining the first value of the second spill flow rate ('iTi-B2Tpp') by feedforward control includes:- determining a sufficient value of the second spill flow rate (T B2TSUff ')a s afunction of a target value of the third flow rate ( mBat) of heat transfer liquid, as a function of a temperature (T5) of the second spill flow rate mT2B) in the return branch to the battery circuit (L_BAT), as a function of a target value T2Tgt) of a temperature of the third flow rate ( i-Bat ') of heat transfer liquid to an inlet of the battery heat exchange device (BAT_HX), and as a function of a temperature (T3) of the third flow rate ( 'ri'tBat ') of heat transfer liquid to an outlet of the battery heat exchange device (BAT_HX), - determining a maximum value of the second spill flow rate (TTLB2TM) as a function of the target value of the third flow rate ( mBat1 QZ ) of heat transfer liquid, as a function of the temperature (T5) of the second spillflow rate (mT2B) inthe return branch towards the battery circuit (L_BAT), as a function of a maximum permissible value ( T2Max) of the temperature of the third flow rate (meat) of heat transfer liquid at the inlet of the battery heat exchange device (BAT_HX), and as a function of the temperature (T3) of the third flow rate (ThBat) of heat transfer liquid at the outlet of the battery heat exchange device (BAT_HX),- determining a reserve value of the second flow rate (mR2T„ ) as a function of a maximum value of said first flow rate 'l''lTrcMax') of heat transfer liquid, as a function of the temperature (T5) of the second spill flow rate (mT2B) in the delivery branch to the battery circuit (L_BAT), as a function of a minimum permissible value(T7Min) he temperature of the first flow rate (mTrc) of heat transfer liquid at an inlet of at least one traction component (TRC), and as a function of the temperature (T3) of the third flow rate (ThBat) of heat transfer liquid at the outlet of the battery heat exchange device (BAT_HX), wherein the minimum permissible value (T7Min) of the temperature of the first flow rate mTrc) of heat transfer liquid at one inlet of at least one traction component (TRC) is a function of a minimum permissible value (74Min) of the temperature of the first flow rate mTrc) of heat transfer liquid at one outlet of at least one traction component (TRC), and wherein the minimum permissible value (T4n,. ) of the temperature of the first flow rate (^rrc) of heat transfer liquid at the outlet of at least one traction component (TRC) is a function of a target value ( ^Tgt.’ Pushcab } of the temperature of the second flow rate (mcafc) °f heat transfer liquid at an inlet of the cabin heat exchange device (CAB_HX),- determining the first value of the second spill flow rate (mB2T) in raw form ( ThB2TpFR) as the greater(22 ) of the sufficient value of the second spill flow rate (T B2TSUff ') and the lower (24 ) of said reserve value of the second spill flow rate (riiB2Tc, and the maximum value of the second spill flow rate'i if there is (SW20, CabRecoverypred= 1) an indication of the possibility of requesting the first spill flow rate (mT2C, mC2T) by the cabin circuit (L_CAB), or as the greater (22 ) between the sufficient value of the second spill flow rate (mB27’Suyy) and the maximum value of the second spill flowrate (biB2Tn) if there is no indication (SW20, CabRecoverypred= 0) of the possibility of requesting the first spill flow rate (mT2C, mC2T) by the cabin circuit (L_CAB),- calculating the value of the second spill flow rate biB2Tpp') determined by feedforward control as the greater (32 ) of a zero value (38 ) and the lower (34 ) of the target value of the third flow rate mBat) of heat transfer liquid, the maximum value of the first flow rate ^TrcMax^ of heat transfer liquid, the maximum value of the second spill flow rate iB2TMI} and a value (36) of the second spill flow rate including at least said first value of the second flow rate in raw form (mR7Trr),^'FFRaw - calculating the second value of the second spill flow rate (ThB2TcL) determined by means of a closed-loop control as a function of an error (ERR) depending at least on the temperature (T4) of the first flow rate (mTrc) of heat transfer liquid at the outlet of at least one traction component (TRC), of the minimum admissible value (T4Mof the temperature of the first flow rate (mTrc) of heat transfer liquid at the outlet of the at least one traction component (TRC), the temperature (T2) of the third flow rate (biBat) of heat transfer liquid at the inlet of the battery heat exchange device (BAT_HX), the maximum permissible value (T2Max) of the temperature of the third flow rate (biBat) of heat transfer liquid atthe inlet of the battery heat exchange device (BAT_HX), and the target value T2Tgt) of the temperature of the third flow rate ( 'ri'tBat ') of heat transfer liquid at the inlet of the battery heat transfer device (BAT_HX).

2. The method of claim 1, wherein determining the target value (TTT-B2TT1 Q rZ ') of the second spill flow rate ( mT2B, mB2T)as acombination of a first value of the second spill flow rate '< TT-B2TFF') determined by means of a feedforward control, and the second value of the second spill flow rate ('1TT-B2TCL') determined by means of a closed- loop control includes determining the greater (2 ) of a zero value (4 ) and the lower ( 6) of:- a sum ( 8 ) of the first value of the second spill flow rate '> TT-B2TFF') determined by means of a feedforward control, and of the second value of the second spill flow rate (TTLB2TCL) determined by means of a closed-loop control,- the target value ( ThBat1 QZ ) of the third flow rate of heat transfer liquid,- a maximum value IVL CZX ) of the first flow rate of heat transfer liquid,the maximum value of the second spill flow rate( TZIDQ'T ) •3. The method of claim 1 or claim 2, where the battery circuit (L_BAT) comprises:an electric battery heater (ECHBat) located upstream of the said battery heat exchange device (BAT_HX) with respect to the third flow direction (F2 ) of that heat transfer liquid,- a third circulation pump (P_BAT) having a delivery port upstream of said electric battery heater (ECHBat) with respect to the third flow direction (F3) of said heat transfer liquid, the third circulation pump (P_BAT) supplying said third flow 'rhBat} to the electric battery heater (ECH) and to the battery heat exchange device(BAT_HX),and wherein the method further includes calculating an additional term (TTLB2TCC) of the first value of the second spill flow rate (mB27’FF)as afunction of an electrical power to be supplied to the electric battery heater and of said temperature (T5) of the second spill flow rate (mT2B) in the delivery branch to the battery circuit (L_BAT) and temperature (T3) of the third flow rate ihBat} of heat transfer liquid at the outlet of the battery heat exchange device (BAT_HX).

4. The method of claim 3, wherein the calculation of the first value of the second flow rateincludes calculating the greater (32 ) of a zero value (34 ) and the lower (36) of the target value of the third flow rate (riiBatT °f heat transfer liquid, the maximum value ^TrcMax} of the first flow rate (mTrc) °f heat transfer liquid, the maximum value of the second spill flow rate (mB2TMa%) and a sum (38 ) of said first value of the second spill flow rate in raw form (mB2Tl,I, ) and‘‘‘‘Raw this additional term (mB2T) of the first value of the Addsecond spill flow ratedetermined by feedforward control.

5. The method any of the foregoing claims, wherein said error (ERR) is determined to be the greater of:- a first difference (43) between a sum (44 ) of the target value (T2Tgt) of the temperature of the third flow rate ('rhBat ') of heat transfer liquid at one inlet of the battery heat exchange device (BAT_HX) with a temperature reserve ( Tpush) of the third flow rate (ThBat) of heat transfer liquid at an inlet of the battery heat exchange device (BAT_HX) and a current value ^inECHBtemperature of the third flow rate (^Bat) of heat transfer liquid at the inlet of the electric battery heater (ECHBat),and one of:the lesser (45) of a second difference (46) between the temperature (T4) of the first flow rate (mTrc) of heat transfer liquid at the outlet of the at least one traction component (TRC) and the minimum permissible value (T4Mof the temperature of the first flow rate (mTrc) of heat transfer liquid at the outlet of the at least one traction component (TRC), and a third difference (47 ) between the maximum permissible value of the temperature (T2) °f the third flow rate (meat) of heat transfer liquid at the inlet of the battery heat exchange device (BAT_HX) and the value (T2) of the temperature of the third flow rate (biBat) of heat transfer liquid at the inlet of the battery heat exchange device (BAT_HX) if there is (SW40, CabRecoverypred= 1) an indication of the possibility of requesting the first spill flow rate {mT2c,'rnC2T) by the cabin circuit (L_CAB).- the third difference (47 ) between the maximum permissible value (?2Ma%) of the temperature (T2) of the third flow rate 'rnBat) of heat transfer liquid at the inlet of the battery heat exchange device (BAT_HX) and the value (T2) of the temperature of the third flow rate (?iiBat) of heat transfer liquid at the inlet of the battery heat exchange device (BAT_HX) if there is no (SW40, CabRecoverypred= 0) an indication of the possibility of requesting the first flow rate {mT2c,'rnC2T) by the cabin circuit (L_CAB).

6. The method of any of the foregoing claims, wherein the second value of the second spill flow rate (mB2TcL) determined by a closed-loop control is calculated by means of a proportional-integral controller (41 ) operating on the basis of that error (ERR) and having a lower saturation limit equal to the opposite of said value of the second spill flow rate TnB2TFF) determined by means of a feedforward control, and an upper saturation limit equal to a difference ( 62 )between the lower of said target value of the third flow rate of heat transfer liquid ('rhBat), said maximum value of the first flow rate of heat transfer liquid ^TrcMax^ / the maximum value of the second spill flow rate (mB2T.. ) and the value of the second spill flow rate(mB27>F) determined by feedforward control.

7. The method of any of the foregoing claims, in which the cabin circuit (L_CAB) also includes:- an electric cabin heater (ECHca ) located upstream of the said cabin heat exchange device (CAB_HX) with respect to the second flow direction (F2 ) of that heat transfer liquid,a second circulation pump (P_CAB) having a delivery port upstream of the said electric cabin heater (ECH) with respect to the second flow direction (F2 ) of the said heat transfer liquid, the second circulation pump (CP) supplying said second flow rate (riiCab) to the electric heater (ECH) and to the second heat exchange device (CAB_HX).

8. The method of any of the foregoing claims, wherein the at least one traction component (TRC) in the traction circuit (L_TRC) includes, for each electric traction motor, at least one hydraulic series between the inverter ( INV1, INV2, INV3, INV4 ) operatively associated with the electric traction motor (Ml, M2, M3, M4 ), the electric traction motor itself (Ml, M2, M3, M4 ), and the heat exchanger for a transmission lubricant (WTOC1, WTOC2, WTOC3, WTOC4 ) of a transmission that connects the electric traction motor (Ml, M2, M3, M4 ) to one or more corresponding drive wheels.

9. The method of claim 8, including a plurality of hydraulic series connected in parallel with each other.

10. The method according to any of the foregoing claims, wherein the minimum permissible value (T4n,. ) of the temperature of the first flow rate (rc) of heattransfer liquid at the outlet of the at least one traction component (TRC) is determined as the sum of the target value T1Tgt,} of the temperature of the second flow rate (Jiicafe) of heat transfer liquid at the inlet of the cabin heat exchange device (CAB_HX) and a temperature reserve (^TPushcab) of the second flow rate (ThCab) of heat transfer liquid at the inlet of the cabin heat exchange device (CAB_HX).

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