Method for heating a traction battery of an electrified vehicle

Abstract

The present invention relates to a method for heating a traction battery (6) of an electrified vehicle, the method comprising the steps of determining a first distribution value (CTR1) for a wheel torque setpoint between a first set of wheels (3) driven by a first drive unit (2) and a second set of wheels (5) driven by a second electric drive machine (4) electrically supplied by the traction battery (6), determining a second distribution value (CTR2) for the wheel torque setpoint, determining a temperature of the traction battery (6), and determining a distribution setpoint (CSCTR) for the wheel torque setpoint by calculating a barycenter of the first distribution value (CTR1) and the second distribution value (CTR2), weighted by the determined temperature of the traction battery (6). The invention relates to hybrid and electric all-wheel-drive vehicles.

Description

[0001] DESCRIPTION

[0002] Title: METHOD FOR HEATING A TRACTION BATTERY BY MANAGING THE MOTOR TORQUE BETWEEN TWO WHEEL SETTINGS

[0003] The present invention claims priority from French application No. 2413558 filed on December 6, 2024, the content of which (text, drawings and claims) is incorporated herein by reference.

[0004]

[0001] The field of the invention relates to a method of heating a traction battery of an electrified vehicle and the management of the distribution of motor torque between two sets of wheels.

[0005]

[0002] Currently, electrified all-wheel-drive vehicles comprise a first set of wheels powered by a first drive unit and a second set of wheels powered by a second electric drive unit. The first drive unit may comprise an internal combustion engine and an electric drive unit. Such an electrified vehicle can therefore be a hybrid vehicle or a fully electric drive vehicle when it is not equipped with the internal combustion engine. In a mild hybrid configuration, the second electric drive unit is arranged to be decoupled from or coupled to the wheels based on criteria such as vehicle speed and outside temperature, in particular, in order to properly manage the dissipation of thermal power by the vehicle's thermal management system.

[0006]

[0003] French patent document FR-A1-3138639 describes a strategy for controlling the coupling of the rear wheel assembly's electric machine to protect the electrical systems against overheating. This strategy provides for ranges of ambient temperature and speed outside of which the rear electric machine is decoupled in order to limit the heat to be dissipated.

[0007]

[0004] In cold weather conditions and when starting the vehicle, the traction battery may be at a temperature below its optimal operating temperature. The discharge power is then limited, potentially to about half its nominal power. These discharge power limitation measures prevent degradation of the traction battery's electrochemical components, but also have the drawback of reducing the performance of the electric motor. This problem is generally solved by thermal preconditioning the traction battery using electric heating. However, these methods draw energy from the battery and further reduce the vehicle's range.

[0008]

[0005] There is therefore a need to address the aforementioned problems.

[0009]

[0006] One objective of the invention is to increase the performance of the electric motor of an electrified vehicle. Another objective is to provide a solution for heating the battery in cold climatic conditions.

[0010]

[0007] More specifically, the invention relates to a method for heating a traction battery of an electrified vehicle comprising the following steps implemented by a control unit of said electrified vehicle:

[0011]

[0008] - the determination, by a first distribution function for a first thermal operating point of the traction battery, of a first distribution value of a setpoint torque at the wheels between a first set of wheels powered by a first drive unit and a second set of wheels powered by a second electric drive machine electrically supplied by the traction battery,

[0012]

[0009] - the determination, by a second distribution function for a second thermal operating point of the traction battery, of a second distribution value of the setpoint torque at the wheels between a first set of wheels powered by a first drive unit and a second set of wheels powered by a second electric drive machine electrically supplied by the traction battery,

[0013]

[0010] - determining the temperature of the traction battery,

[0014]

[0011] - the determination of a setpoint for the distribution of said setpoint torque to the wheels by calculating a centroid of the first distribution value and the second distribution value weighted by the determined temperature of the traction battery.

[0015]

[0012] The method according to the invention may include the following additional features, alone or in combination:

[0016]

[0013] - The center of mass is configured such that the weighting of the second distribution value is greater than the weighting of the first distribution value when the determined temperature of the traction battery is below a temperature threshold.

[0014] - The center of mass is configured such that, as the determined temperature of the traction battery increases, the weighting of the first distribution value increases and the weighting of the second distribution value decreases inversely proportionally to the increase in the weighting of the first distribution value.

[0017]

[0015] - The weighting of the first and second distribution value is obtained by a predetermined mapping taking as input the determined temperature of the traction battery.

[0018]

[0016] - The first and second distribution functions of said setpoint torque determine respectively the first and second distribution value as a function of the vehicle speed and the outside temperature of said vehicle.

[0019]

[0017] - The second distribution function is configured to allocate the entire setpoint torque to the wheels to the second electric drive machine when the outside temperature of said vehicle is below a temperature level between -5°C and 5°C.

[0020]

[0018] - The second distribution function is configured to allocate the entire setpoint torque to the wheels to the second electric drive machine when the vehicle speed is below a speed level between 5km / h and 15km / h.

[0021]

[0019] - The control of a thermal regulation fluidic loop of at least the traction battery and the second electric machine so as to transfer calories generated by the second electric machine to the traction battery.

[0022]

[0020] It is further provided an electrified vehicle comprising a traction battery, a first wheel set powered by a first drive unit, a second wheel set powered by a second electric drive machine electrically supplied by the traction battery, a thermal regulation fluid loop comprising at least the traction battery and the second electric machine, a control unit, in which the control unit is configured to implement the traction battery heating method according to any one of the preceding embodiments of the invention.

[0023]

[0021] The invention further provides for a computer program comprising instructions which, when the program is executed by a control unit of such an electrified vehicle, lead the latter to implement any one of the embodiments of the traction battery heating method according to any one of the preceding embodiments of the invention.

[0024]

[0022] The invention is a software control solution for improving the thermal preconditioning of a traction battery for an all-wheel-drive electrified vehicle. It does not require significant additional computing power and adds a heating function that complements the existing overheat protection function of the power electronics. The two functions are combined through the management of wheel torque distribution by calculating the center of gravity.

[0025]

[0023] Other features and advantages of the present invention will become more apparent upon reading the following detailed description, which includes embodiments of the invention given by way of non-limiting examples and illustrated by the accompanying drawings, in which:

[0026]

[0024] [Fig.1] schematically represents an architecture of an all-wheel drive hybrid electrified vehicle designed to implement the traction battery heating process by managing engine torque distribution.

[0027]

[0025] [Fig.2] represents a fluidic loop of a thermal regulation system of the electrified vehicle allowing the heating of the battery.

[0028]

[0026] [Fig.3] represents a block diagram of a wheel torque control function implementing the method according to the invention.

[0029]

[0027] [Fig.4] represents in more detail an embodiment of the center of gravity function of the torque distribution values ​​setpoint to the wheels according to the invention.

[0030]

[0028] [Fig.5] is a logic diagram schematically representing the traction battery heating process according to the invention.

[0031]

[0029] The invention applies to electrified vehicles comprising electric traction, that is to say, comprising an electric drive machine and power electronics powered by a traction battery. It relates in particular to all-wheel drive electrified motor vehicles or any vehicle comprising at least two sets of motorized wheels, with fully or partially electric motors.

[0030] Figure 1 shows a preferred embodiment of an electrified motor vehicle architecture 1 adapted for implementing the traction battery heating method.

[0032]

[0031] The vehicle 1 comprises a first drive unit 2 configured to drive a first set of wheels 3 and an electric drive machine 4 configured to drive a second set of wheels 5. In this example, the first set of wheels 3 is the front set of vehicle 1 and the second set of wheels 5 is the rear set.

[0033]

[0032] The first drive unit 2 comprises an internal combustion engine 12 including a drive shaft mechanically connected in rotation to a first coupling and uncoupling device 14, a first electric drive machine 13 whose rotor is mechanically connected in rotation to a torque transmission element at the output of the first coupling and uncoupling device 14, a second coupling and uncoupling device 15 mechanically connected in rotation to the transmission element and a gear reduction gearbox 16 connected at the output of the second coupling and uncoupling device 15. The output shaft of the gear reduction gearbox 16 is mechanically connected to the drive wheels by a transmission.

[0034]

[0033] The first electric drive unit 13, the first and second coupling and uncoupling devices 14 and 15, and the gear reduction unit 16 are mounted in a block forming an electrified dual-clutch gearbox. The first electric drive unit 13 is adapted to transmit engine torque to the wheels independently or in conjunction with the internal combustion engine 2 by coordinated control of the first and second coupling and uncoupling devices 14 and 15. The first drive unit 2 thus constitutes a parallel hybrid powertrain. The first electric drive unit 13 is a permanent magnet synchronous machine operating at 48 volts and with a rated power of approximately 20 kW.

[0035]

[0034] Other variants of the first drive unit 2 are conceivable for powering the first wheel assembly 3. For example, the drive unit may be a purely internal combustion engine drive unit, or a purely electric drive unit. Furthermore, other variants of motor torque transmission are conceivable where the gear ratio is modified by a continuously variable transmission, for example. The electric machine of the first drive unit 2 may be a machine operating on single-phase, three-phase, or direct current and at higher voltage levels, up to several hundred volts, for example. It will therefore be understood that the first drive unit 2 may be of the internal combustion, hybrid, or fully electric type and may consist of an alternating current torque transmission configuration.

[0036]

[0035] The second wheel set 5 is driven by the second electric machine 4, whose rotor is mechanically connected in rotation by a transmission member 18 to the input of a coupling and decoupling device 17, which is mechanically connected in rotation at its output to a speed reduction member 19. In this example, the speed reduction member 19 is a single-speed gearbox and the coupling and decoupling device 17 is a dog clutch. The dog clutch 17 is capable of being configured in a locked state in which the second electric drive machine 4 is coupled to the wheels of the second wheel set 5 and in an unlocked state in which the second electric drive machine 4 is decoupled from the wheels.

[0037]

[0036] The transmission of the second wheel set 5 is mechanically separated from the drive unit 2; in other words, there is no drive shaft between the first wheel set 3 and the second wheel set 5. The second electric machine 4 is a permanent magnet synchronous machine operating at 48 volts and with a rated power of up to 20 kW. Alternatively, the second electric machine 4 can be a machine operating at single-phase, three-phase, or direct current voltage and at higher voltage levels, for example, up to several hundred volts.

[0038]

[0037] The vehicle 1 includes a traction battery 6 configured to electrically power the first electric machine 13 and the second electric machine 4 when they provide motor torque to the wheels. The traction battery 6 is rechargeable and consists of electrochemical energy storage elements. An electrochemical energy storage element, also called an electrochemical cell, can be of the Lithium-ion type (lithiumized Nickel Manganese Cobalt Oxide (NMC) or lithium iron phosphate (LFP) can be cited as examples of active materials for the positive electrode), Nickel Cadmium (Ni-Cd), Nickel Metal Hydride (Ni-MH), or Sodium-ion type. The traction battery 6 has a capacity of up to several kWh.

[0039]

[0038] In addition, the vehicle 1 may include a battery charging interface 6 from an external power source. But this is not mandatory.

[0040]

[0039] The vehicle 1 further includes a power converter 7 electrically connected to the battery 6 to supply a service battery 9 and an on-board network 8 operating at 12 volts.

[0041]

[0040] The vehicle 1 further comprises a starter 10 mechanically connected in rotation by a transmission element to the drive shaft of the internal combustion engine 12. The starter is of the "Stop and Start" type. The vehicle 1 further comprises an air conditioning compressor driven in rotation by the internal combustion engine 12.

[0042]

[0041] The vehicle 1 further comprises a control unit 20 configured to supervise the functions of the vehicle 1, and in particular to determine a motor torque at the wheels representative of the driver's intent. The control unit 20 comprises a computer and memory adapted for the execution of vehicle management functions.

[0043]

[0042] More specifically, the engine torque at the wheels is determined from the depressment of an accelerator or brake pedal, the value of which depends on predetermined calibrations in the memory of the control unit 20 and which is a function of the vehicle speed and a pedal depressment parameter.

[0044]

[0043] The control unit 20 further implements a function for managing the distribution of motor torque to the wheels between the first drive unit 2 of the first wheel set 3 and the second electric motor 4 of the second wheel set 5. The motor torque to the wheels is distributed according to distribution values ​​CTR1 and CTR2 between the first drive unit 2 and the second electric motor 4 to provide the torque requested by the driver. A distribution value is a dimensionless value between 0 and 1, or 0% and 100%.

[0045]

[0044] Furthermore, the motor torque distribution management function is configured to calculate a CSCTR distribution setpoint for said setpoint torque at the wheels resulting from the first distribution value CTR1 and the second distribution value CTR2 as a function of the traction battery temperature 6. The calculation method will be described in more detail later in the description. The CSCTR setpoint is intended to control the motor torque generated by the drive unit 2 and the second electric machine 4, as well as the motor torque transmission devices for each wheel set, including the locked and unlocked state of device 17.

[0046]

[0045] When the distribution value is equal to 100%, the entire motor torque at the wheels is requested from the first drive unit 2 of the first wheel set 3. In this situation, the motor torque at the wheels is supplied by the internal combustion engine 12 and / or the first electric drive machine 13. The second electric drive machine 4 is decoupled from the second wheel set 5. The coupling and decoupling device 17 is configured in the unlocked state.

[0047]

[0046] When the distribution value is equal to 50%, half of the motor torque at the wheels is requested from the first drive unit 2 of the first wheel set 3, supplied by the internal combustion engine 12 and / or the first electric drive machine 13 and the other half of the motor torque at the wheels is requested from the second electric drive machine 4, which is then coupled to the second wheel set 5. The coupling and decoupling device 17 is configured in the locked state.

[0048]

[0047] When the distribution value is equal to 0%, the entire motor torque to the wheels is then requested from the second electric drive machine 4. The coupling and decoupling device 17 is configured in the locked state.

[0049]

[0048] These distribution values ​​are not limiting; other examples of distribution values ​​between 0% and 100% are conceivable. Furthermore, due to the limited power of the second electric machine 4, a function is provided to activate the supply of additional torque by the first drive unit 2 when the second electric machine 4 reaches its maximum torque limit.

[0050]

[0049] To put into operation the heating of the traction battery 6 in accordance with the method according to the invention, the vehicle 1 includes a thermal regulation system comprising a fluidic loop including at least the traction battery 6 and the electric machine 4.

[0051]

[0050] Figure 2 schematically illustrates an embodiment of the fluid loop BF1. In this figure, elements identical to those described previously are designated by the same reference numerals.

[0051] The fluid loop BF1 comprises a heat transfer fluid circuit 21, for example water, and heat exchangers 22 to 25 arranged to extract heat generated by the power electronics of the traction battery 6, the first electric machine 13, the second electric machine 4, and the power converter 7. A pump 27 is arranged to circulate the heat transfer fluid in the fluid loop BF1. The fluid loop BF1 includes a heat exchanger 28 arranged in heat exchange with another fluid loop BF2 of the thermal control system, enabling heat exchange between the two loops BF1 and BF2.The other loop BF2 can be the vehicle's air conditioning circuit, and the heat exchanger 28 acts as a heat exchanger between the heat transfer fluid of the fluid loop BF1 and a heat transfer fluid, for example, Freon, from the air conditioning loop BF2. The fluid loop BF1 also includes a bypass circuit for the heat transfer fluid to a radiator 26, positioned at the front of the vehicle, in order to dissipate heat by means of ventilation. Means for controlling the circulation of the heat transfer fluid are provided, such as a fluid temperature sensor 29, an outside temperature sensor 30, a heat transfer fluid distribution valve 31, and a pump control element 27. Other arrangements of the thermal regulation system are conceivable without departing from the scope of the invention.It will be understood, however, that at least the traction battery 6 and the electric machine 4 are arranged together in the same fluid loop, which is adapted to allow the battery to be heated when the second electric machine 4 and its power electronics generate heat. Optionally, the heat exchangers of the first electric machine 13 and the power converter 7 can be arranged in a separate fluid loop.

[0052]

[0052] The BF1 fluidic loop is controllable to control the heat transfer fluid at the output of the power electronics to the radiator 26, then the heat exchanger 28 and then to the traction battery 6, or directly to the heat exchanger 28 and the traction battery 6.

[0053]

[0053] In addition, the cooling of the internal combustion engine is implemented by a dedicated fluidic loop, fluidically independent of the BF1 loop.

[0054]

[0054] In Figure 3, the FGC management function of the engine torque distribution to the wheels, implemented by the vehicle control unit 20, is schematically represented in the form of a functional block diagram.

[0055] According to the invention, the control unit 20 implements a first distribution function F1 for a first thermal operating point of the traction battery 6, configured to determine a first distribution value CTR1 of a setpoint torque at the wheels between the first wheel set 3 and the second wheel set 5. This first function F1 corresponds to a battery operating point under optimal thermal conditions, or hot conditions. The first function F1 is configured primarily to prevent overheating of the electrical systems.

[0055]

[0056] The control unit 20 implements a second distribution function F2 for a second thermal operating point of the traction battery 6, configured to determine a second distribution value CTR2 of a setpoint torque at the wheels between the first wheel set 3 and the second wheel set 5. This second function F2 corresponds to a cold operating point of the battery, i.e., when the temperature of the traction battery 6 causes a limitation in the discharge power. This second distribution function F2 is configured to favor the use of the second electric machine 4 in wider speed and ambient temperature ranges than the first distribution function F1 in order to demand more power from the second electric machine 4 and increase the thermal power transferred to the traction battery 6.The CTR2 distribution values ​​are therefore configured to favor the heating of the traction battery 6 for predetermined operating points of the vehicle depending in particular on the temperature of the traction battery 6.

[0056]

[0057] The first and second distribution functions F1 and F2 of said setpoint torque determine respectively the first and second distribution values ​​CTR1 and CTR2 as a function of the vehicle speed Vit and the outside temperature Text of said vehicle.

[0057]

[0058] More specifically, the CTR1 and CTR2 distribution values ​​are determined from maps stored in the memory of the control unit 20, which take as input the vehicle speed (Vit) and outside temperature (Text) parameters. These parameters are measured by sensors designed for this purpose.

[0058]

[0059] For example, these torque distribution functions F1 and F2 are configured so that the second electric motor 4 is decoupled from the wheels when the vehicle speed reaches or exceeds a maximum speed limit between 80 km / h and 100 km / h. This configuration is designed to mechanically protect the second electric motor 4 and the dog clutch 17.

[0059]

[0060] As an indicative example, the first distribution function F1 is configured so that the engine torque distribution value to the first wheel set 3 is 50% for the following conditions: when the outside temperature is in a range between -30°C and 0°C; when the outside temperature is between 0°C and 30°C and the vehicle speed is less than 60km / h; when the outside temperature is between 30°C and 55°C and the vehicle speed is less than 15km / h.

[0060]

[0061] The second distribution function F2 differs from the first function F1 in that the torque distribution value to the first set of wheels is 0%. In other words, the entire torque set to the wheels is allocated to the second electric motor, under the following conditions: when the outside temperature of the vehicle is below a temperature range between -5°C and 5°C; and when the vehicle speed is below a speed range between 5 km / h and 15 km / h. This difference in calibration prioritizes the use of the second electric motor 4 to heat the traction battery 6.

[0061]

[0062] These calibration values ​​for functions F1 and F2 are provided as a non-limiting example. Other values ​​may be considered depending on the cooling capacity of the thermal management system and the power of the electrical systems. Outside these ranges, the engine torque distribution value to the first axle is set to 100%.

[0062]

[0063] Furthermore, the FGC engine torque management function includes a function F3 for calculating a center of gravity which provides a torque distribution setpoint CSCTR to the wheels by calculating a center of gravity of the first distribution value CTR1 and the second distribution value CTR2 weighted by the temperature Tbat of the traction battery. This function ensures that the action is distributed between the two functions F1 and F2 at all times according to the instantaneous temperature of the traction battery 6.

[0063]

[0064] Figure 4 shows an embodiment of function F3 as a functional block diagram. Function F3 includes a mapping 41 that takes the traction battery temperature Tbat as an input parameter and outputs a weighting U based on the battery temperature. U is a dimensionless value between 0 and 1 and determines the weighting of the first distribution value CTR1, with a value of U, and the weighting of the second distribution value CTR2, with a value of 1 - U.

[0064]

[0065] More specifically, the center of gravity is configured so that as the traction battery temperature (Tbat) increases, the weighting factor (U) of the first distribution value (CTR1) increases, and the weighting factor (1 - U) of the second distribution value (CTR2) decreases inversely. In other words, at a low traction battery temperature (Tbat), for a minimum temperature limit, the weighting factor (U) is equal to 0. As the traction battery temperature (Tbat) increases, the weighting factor (U) gradually increases until it reaches the value 1. This value is set when the battery temperature reaches nominal operating thermal conditions.

[0065]

[0066] More specifically, the center of gravity is configured so that the weighting of the second distribution value CTR2 is greater than the weighting of the first distribution value CTR1 when the traction battery temperature Tbat is below a temperature threshold ST. The evolution of the weighting U can be linear or non-linear.

[0066]

[0067] Other implementation methods allowing allocation between the two maps are conceivable by a person skilled in the art.

[0067]

[0068] Figure 5 illustrates the traction battery heating process with a block diagram. This heating process is implemented by the vehicle's control unit 20. The control unit 20 is equipped with an integrated circuit computer and electronic memory, the computer and memory being configured to execute the heating process according to the invention. However, this configuration is not mandatory. The computer could be external to the control unit 20, while still being coupled to it. In this latter case, it could itself be configured as a dedicated computer, possibly including a dedicated program. Consequently, the control unit, according to the invention, can be implemented as software modules, electronic circuits, or hardware, or a combination of electronic circuits and software modules.

[0069] The vehicle is in motion at a non-zero speed. The control unit is performing the function of managing engine torque distribution to the wheels.

[0068]

[0070] To this end, the method comprises, in a first step E1, the determination of the vehicle speed parameters Vit and the ambient temperature Text. This step consists of determining the parameters that subsequently allow the distribution values ​​CTR1 and CTR2 of the setpoint torque at the wheels between the first and second sets of wheels to be determined by the functions F1 and F2, respectively.

[0069]

[0071] The process further includes a determination step E2, using the first distribution function F1 for a first thermal operating point of the traction battery, of the first distribution value CTR1 of a setpoint torque at the wheels between the first wheel set 3 driven by the first drive unit 2 and the second wheel set 5 driven by the second electric drive machine 4, which is electrically powered by the traction battery 6. CTR1 is a value between 50% and 100%, i.e., at 50%, half the torque is distributed to the first wheel set and half to the second wheel set, and at 100%, all the torque is distributed to the first wheel set. In this latter case, the second electric drive machine is decoupled from the wheels to prevent overheating of the systems.

[0070]

[0072] The method further includes determining E3 the second CTR2 torque distribution value at the wheels using the second distribution function F2 for a second thermal operating point of the traction battery. For example, CTR2 is configured to 0% or 100% depending on predetermined ranges of vehicle speed and outside temperature. At 0%, all the torque is distributed to the second set of wheels to promote battery heating. At 100%, all the torque is distributed to the first set of wheels.

[0071]

[0073] The process further includes in a fourth step E4 the determination of the temperature of the traction battery Tbat in order to determine the weighting value of each distribution value CTR1 and CTR2.

[0072]

[0074] The process further includes in a fifth step E5 the determination of the distribution setpoint CSCTR of said setpoint torque at the wheels by calculation of the centroid of the first distribution value CTR1 and the second distribution value CTR2 weighted by the temperature determined Tbat of the traction battery.

[0075] During this step E5, the weightings U and 1-U of the first and second distribution values ​​CTR1 and CTR2, respectively, are obtained by predetermined mapping that takes the traction battery temperature Tbat as input. The center of gravity is configured so that the weighting 1-U of the second distribution value CTR2 is greater than the weighting U of the first distribution value CTR1 when the traction battery temperature Tbat is below the temperature threshold ST. In other words, when the traction battery is cold.

[0073]

[0076] Furthermore, the center of gravity is configured so that as the traction battery temperature (Tbat) increases, the U weighting of the first distribution value (CTR1) increases, and the 1-U weighting of the second distribution value decreases inversely. Thus, when the battery is hot, the U weighting of the first distribution value (CTR1) is greater than the 1-U weighting of the second distribution value. The motor torque management system, which prevents overheating of the electrical systems, is then fully active.

[0074]

[0077] During driving, when the traction battery is cold, the heating process includes in a sixth step E6 the control of the fluidic loop BF1 so as to transfer thermal power generated by the electric traction machine 4 to the traction battery 6, preferably directly to the traction battery 6. The control of the fluidic loop includes the activation command of the heat transfer fluid pump and, optionally, the control of the distribution valve to activate or not the bypass through the radiator.

[0075]

[0078] Thermal power transfer can occur after the heat transfer fluid passes through the radiator 26. A portion of the heat is then dissipated to the external environment by the radiator, and the excess heat is absorbed by the traction battery 6, thus heating it. Due to the balance between the two functions F1 and F2, the thermal power transferred is proportionally greater when the traction battery is cold, that is, when the determined temperature of the traction battery is below the temperature threshold ST defined by the map 41.

[0076]

[0079] Then, when the battery is hot, function F1 is fully active, and the heating process includes a sixth stage, E6, which controls the BF1 fluid loop to dissipate heat to the radiator. If the dissipation potential is reached, the second electric machine is decoupled. This action occurs within ranges predetermined by function F1, at high vehicle speeds and high ambient temperatures.

[0077]

[0080] The invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different embodiments of the invention by combining, for example, the different features mentioned above, taken alone or in combination, without departing from the scope of the invention.

Claims

DEMANDS 1. Method for heating a traction battery (6) of an electrified vehicle comprising the following steps implemented by a control unit (20) of said electrified vehicle: - the determination (E2), by a first distribution function (F1) for a first thermal operating point of the traction battery (6), of a first distribution value (CTR1) of a setpoint torque at the wheels between a first set of wheels (3) powered by a first drive unit (2) and a second set of wheels (5) powered by a second electric drive machine (4) electrically supplied by the traction battery (6), - the process being characterized in that it further comprises: - the determination (E3), by a second distribution function (F2) for a second thermal operating point of the traction battery (6), of a second distribution value (CTR2) of a setpoint torque at the wheels between a first set of wheels (3) powered by a first drive unit (2) and a second set of wheels (5) powered by a second electric drive machine (4) electrically supplied by the traction battery (6), - the determination (E4) of a temperature (Tbat) of the traction battery (6), - the determination (E5) of a distribution setpoint (CSCTR) of said setpoint torque to the wheels by calculating a centroid of the first distribution value (CTR1) and the second distribution value (CTR2) weighted by the determined temperature (Tbat) of the traction battery (6).

2. Method according to claim 1 wherein the center of gravity is configured such that the weighting of the second distribution value (CTR2) is greater than the weighting of the first distribution value (CTR1) when the determined temperature (Tbat) of the traction battery (6) is less than a temperature threshold (ST).

3. A method according to claim 1 or 2 wherein the center of gravity is configured such that, when the determined temperature (Tbat) of the traction battery (6) increases, the weighting of the first distribution value (CTR1) increases and the weighting of the second distribution value (CTR2) decreases accordingly. inversely proportional to the increase in the weighting of the first distribution value (CTR1).

4. Method according to any one of claims 1 to 3 wherein the weighting of the first and second distribution value (CTR1, CTR2) is obtained by a predetermined mapping (41) taking as input the determined temperature (Tbat) of the traction battery (6).

5. A method according to any one of claims 1 to 4 wherein the first and second distribution functions (F1, F2) of said setpoint torque respectively determine the first and second distribution values ​​(CTR1, CTR2) as a function of the vehicle speed (Vit) and the outside temperature (Text) of said vehicle.

6. Method according to claim 5 wherein the second distribution function (F2) is configured to allocate the entire setpoint torque to the wheels to the second electric drive machine (4) when the outside temperature (Text) of said vehicle is below a temperature level between -5°C and 5°C.

7. Method according to claim 5 or 6 wherein the second distribution function (F2) is configured to allocate the entire set torque to the wheels to the second electric drive machine (4) when the vehicle speed is below a speed level between 5km / h and 15km / h.

8. A method according to any one of claims 1 to 7 further comprising the control of a fluidic loop (BF1) for thermal regulation of at least the traction battery (6) and the second electric machine (4) so ​​as to transfer calories generated by the second electric machine (4) to the traction battery (6).

9. Electrified vehicle comprising: - a traction battery (6), - a first set of wheels (3) powered by a first drive unit (2), - a second set of wheels (5) powered by a second electric drive machine (4) electrically supplied by the traction battery (6), - a fluidic loop (BF1) for thermal regulation comprising at least the traction battery (6) and the second electric machine (4), - a control unit (20), - the electrified vehicle being characterized in that the control unit (20) is configured to implement the traction battery heating method (6) according to any one of claims 1 to 8.

10. Computer program comprising instructions which, when the program is executed by a control unit (20) of an electrified vehicle according to claim 9, cause the latter to implement any one of the embodiments of the traction battery heating method according to any one of claims 1 to 8.

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