METHOD FOR CHARGING A BATTERY BASED ON THE EXTERNAL ENVIRONMENTAL TEMPERATURE FOR A FAST CHARGING MODE

Abstract

The present invention relates to a method for recharging a traction battery (3) for a rechargeable electrified vehicle (1) by means of a charging terminal (7) in which a predetermined charging mode is configured determining a first charging current setpoint CR1 for controlling the terminal (7), comprising the control of a first charging phase controlled by the first current setpoint CR1 as long as the state of charge of the battery (3) is lower than a predetermined state of charge threshold, the control of a second charging phase when the state of charge is higher than said state of charge threshold comprising the control of the charging current as a function of the temperature of the external environment of the vehicle with respect to a predetermined temperature threshold. Figure 1

Description

Title of the invention: METHOD FOR RECHARGING A BATTERY BASED ON THE EXTERNAL ENVIRONMENTAL TEMPERATURE FOR A FAST RECHARGING MODE

[0001] The field of the invention relates to a method for recharging a traction battery of a rechargeable electrified vehicle.

[0002] Rechargeable electrified motor vehicles comprise a traction battery, generally of high power, which can be recharged on an electrical supply network external to the vehicle. Such vehicles are equipped with a charging device whose function is to control the current delivered by a terminal. The charging devices are generally adapted for different charging modes determining the charging power. For a charging mode called mode 2 operated from a conventional domestic AC voltage socket, the power is between 1 kW and 4 kW. For a higher power charging mode, called mode 3 and operated from a three-phase type socket, the power can reach 44 kW.Finally, fast charging, known as mode 4, the electrical voltage delivered by the terminal is of the direct voltage type and operates at powers greater than 50kW and up to 350 kW, involving charging currents which can reach values ​​between 100A and 350A.

[0003] Fast charging aims to fully recharge the battery in about thirty minutes to one hour. This involves significant electrical power flows through the battery which generate a rise in temperature. It is necessary to control and evacuate the calories in order to avoid damage to the electrical circuits and the battery. For this purpose, these vehicles are equipped with a thermal regulation system generally comprising a dedicated circuit for cooling the battery. In addition, thermal protection measures triggering current limitations are also provided. Most often, these are triggered when the temperature of the battery and the cooling circuit exceeds predetermined thresholds.

[0004] Furthermore, document FR2999812A3 is known describing a cooling system optimized for so-called fast charges comprising two heat transfer fluid circulation circuits. Document CN109378536A is also known describing the management of charging and discharging of an electrified vehicle battery.

[0005] During an electric recharge at a terminal, according to hydraulic architectures of the cooling systems, the battery cooling circuit is isolated. Then When driving, some architectures allow a transfer of calories from the battery cooling circuit to another circuit where the vehicle's radiator is located. This reduces energy consumption while driving for the battery's cooling needs. However, this particular configuration tends to cause an undesirable effect in the event of a significant transfer of calories between the two hydraulic circuits when driving resumes.In fact, in very hot climatic situations, that is to say for vehicle ambient temperatures above 40° Celsius, it happens that following a rapid electric recharge the calories accumulated by the battery thermal regulation system can be transferred to the passenger compartment thermal regulation circuit and ultimately into the passenger compartment, when the VHL resumes driving, thus causing an undesirable heat stroke effect at the time of this resumption of driving.

[0006] The invention aims to overcome the aforementioned problems. One objective of the invention is to avoid the effects of heat surge in the passenger compartment in situations of high external heat when returning to the road following a rapid recharge.

[0007] More specifically, the invention relates to a method for recharging a traction battery for a rechargeable electrified vehicle by means of a charging terminal in which a predetermined charging mode is configured determining a first charging current setpoint CRI for controlling the terminal. According to the invention, the method comprises the following successive steps during a charging session controlled according to said charging mode: - The control of a first recharge phase controlled by the first CRI current setpoint as long as the battery charge state is below a predetermined charge state threshold, - Controlling a second charging phase when the state of charge is higher than said state of charge threshold, comprising controlling the charging current as a function of the temperature of the vehicle's external environment relative to a predetermined temperature threshold.

[0008] According to a variant, the control of the recharge current is controlled by the first current setpoint CRI if the environmental temperature is lower than said temperature threshold, and when the environmental temperature is higher than or equal to said temperature threshold, the control of the recharge current is controlled by a second recharge current setpoint CR2 having a value which is a function of a predetermined reduction coefficient k according to the following relationship: CR2=k*CR1, with k between 0.2 and 0.8.

[0009] According to a preferred embodiment, the first instruction is configured to control a continuous type recharge current having a value greater than 100 amperes until a level of approximately 80% of the total capacity of the battery.

[0010] According to one variant, the state of charge threshold is between 40% and 80% of the total capacity of the battery.

[0011] According to a preferred variant, the state of charge threshold is equal to approximately 60% of the total capacity of the battery.

[0012] According to a variant, said temperature threshold is equal to approximately 40° Celsius.

[0013] According to a variant, the second current setpoint is a limitation setpoint. of the maximum value of the charging current.

[0014] The invention also provides a device for controlling the charging current of a traction battery for a rechargeable electrified vehicle in which a predetermined charging mode is configured by means of a charging terminal determining a first charging current setpoint CRI for controlling the terminal, comprising a means for measuring the temperature of the environment outside the vehicle, a means for measuring the state of charge of the battery, which is configured to implement the charging method according to any one of the preceding embodiments.

[0015] The invention further provides a rechargeable electrified vehicle comprising a traction battery and a device for controlling the charging current in accordance with the invention.

[0016] The invention improves driving comfort and in particular the management of the passenger compartment temperature for rapid recharging in extremely hot climatic situations.

[0017] Other characteristics and advantages of the present invention will appear more clearly on reading the detailed description which follows, comprising embodiments of the invention given as non-limiting examples and illustrated by the appended drawings, in which:

[0018] [Fig.l] schematically represents an electrified motor vehicle comprising a control unit capable of implementing the recharging method according to the invention;

[0019] [Fig.2] schematically represents an embodiment of the recharging method according to the invention;

[0020] [Fig.3] is a graph illustrating the control of the charging current during the execution of the method according to the invention.

[0021] The invention applies to electrified vehicles, in particular rechargeable, hybrid and electric motor vehicles. In the present description, the term approximately means + / -10% of the indicated value and the limits of a range of values ​​are included in the range.

[0022] In [Fig.l], an example of an electrified vehicle 1 capable of implementing the invention is shown. The vehicle 1 comprises a powertrain provided with a unit of control 2, of an electric traction machine (not shown) powered by a traction battery system 3 and a battery recharging device 9.

[0023] In this example, the control unit 2 is a computer member whose function is to centralize the data collected from the vehicle and to retransmit them to one or more computers of the vehicle. The control unit 2 is connected to a temperature sensor T of the external environment of the vehicle and is capable of communicating this data permanently to the other computers of the vehicle. The control unit 2 can perform other functions of controlling and coordinating the actuators of the vehicle, for example the energy strategy functions, or even the control of the electric traction.

[0024] The battery system 3 comprises a high-voltage electric battery, generally of several hundred volts, for example 450V at full charge, ensuring the supply of electrical energy to the electric machine. The electric battery comprises electric cells, for example of the Lithium-ion type. The battery system 3 comprises a control device 4 for managing the battery system. This device 4 is capable of delivering to other computers of the vehicle information on the state of the battery, such as the state of charge, the temperature, the charging current, the no-load voltage in particular, as well as instructions to a charging terminal, for example a charging mode, a charging power, a charging current, or a current limitation command, in particular to the computer of the charging device 9.

[0025] Furthermore, the control device 4 is able to receive information from the computer of the control unit 2 for the purpose of controlling charging at a terminal. The computer 4 is able to receive the external environment temperature T of the vehicle 1 obtained from the temperature sensor of the vehicle or from a navigation system of the vehicle.

[0026] In the context of the invention, the data of the instantaneous state of charge of the battery and the environmental temperature T are used to determine the control of a recharging current setpoint CRI and CR2 when the environmental temperature T is high, and when the state of charge level reaches a predetermined level, and preferably during an operation of a so-called rapid recharging mode of high power, greater than 50kW. The recharging current setpoint may be a current value or a maximum current limitation value.

[0027] The charging device 9 comprises charging means cooperating with a power outlet 6 so as to be able to connect electrically to an external charging terminal 7 connected to an electrical supply network 8. Its function is to manage the communication between the different charging terminals and to monitor and control the electrical charging at the terminal. The charging device 9 comprises also an AC / DC and DC / DC alternating current converter. The charging device 9 controls a charging instruction defining a charging voltage and a charging current. The instruction is transmitted to the terminal when the vehicle is connected. In the context of the invention, the charging device 9 delivers the charging current instruction in accordance with the method according to the invention to avoid an undesirable rise in temperature in the passenger compartment of the vehicle following charging at the terminal.

[0028] To ensure thermal protection of the battery 3 and the charging device 9, the powertrain also comprises a thermal regulation system 5 for the on-board electrical systems, illustrated schematically in [Fig.l]. In this non-limiting example, the thermal regulation system 5 is a thermodynamic cycle loop type circuit consisting of a heat transfer fluid cooling circuit and heat exchange elements 51, 52, 53, such as condensers, evaporators and radiators. It may comprise mechanical ventilation means depending on the cooling architecture. In a non-limiting example of architecture, the thermal regulation system 5 comprises a thermal regulation circuit intended for cooling an electric traction machine and the charging device 9. Another circuit is intended for cooling the passenger compartment. Another circuit is dedicated to cooling the battery.The architecture is capable of transferring calories between circuits according to the regulation strategy, and of isolating a circuit from one or more other circuits by means of circulation valves.

[0029] The control device 4 comprises an integrated circuit computer and electronic memories and is configured to control the recharging method according to the invention. The computer could be external to the battery system, while being coupled to the latter. In the latter case, it can itself be arranged in the form of a dedicated computer comprising a possible dedicated program, for example. Consequently, the control device 4, according to the invention, can be produced in the form of software modules (or computer modules (or even "software")), or electronic circuits (or "hardware"), or even a combination of electronic circuits and software modules.

[0030] [Fig. 2] represents a flowchart of an embodiment of the charging method. In a first step of the method, the vehicle is in an electrical charging situation at terminal 20. The vehicle's charging socket is electrically connected to the electrical supply terminal. During a first phase of the charging session, the electrical charging is triggered in a fast charging mode, with a power greater than 50kW. The charging current setpoint CRI is controlled by the vehicle's charging device to a value between 100A and 500A. In the case of the fast charging mode, the setpoint is configured to control a continuous type recharge current until a level of approximately 80% of the total capacity of the battery is reached, subject to the control that the thermal conditions inherent to the battery for its proper functioning allow it.

[0031] In a preferred embodiment of the invention, the recharging method is triggered only for a so-called rapid recharging mode, i.e. for recharging powers greater than 50kW and recharging current of a value between 100 amps and 350 amps.

[0032] In this example of the charging session, the environmental temperature measured by the vehicle sensor is greater than 40° Celsius.

[0033] During electrical recharging 20, the battery control device continuously performs periodic monitoring 21 of the instantaneous state of charge of the battery with respect to a predetermined threshold SI, the value of which is between 40% and 80% of the total capacity of the battery. The threshold SI is the level from which the recharging speed is chosen to reduce to limit the temperature rise at the end of recharging. This has the effect of limiting overheating when resuming driving. The threshold is preferably between 60% and 80% of the full capacity of the battery. This is an optimal setting making it possible to avoid overheating in the passenger compartment when resuming while maintaining a satisfactory recharging time.

[0034] As long as the instantaneous state of charge is less than SI, the recharge current is controlled in accordance with the CRI setpoint, regardless of the environmental temperature value.

[0035] If the instantaneous recharge state is equal to or greater than SI, the method comprises a step of verifying the ambient temperature of the vehicle with respect to a predetermined threshold TL. Depending on the value of the ambient temperature, the recharge device controls either the current setpoint CRI or a current setpoint CR2, lowered with respect to CRI. This verification aims to detect situations of high heat to trigger a limitation of the charging current in order to avoid the heat stroke effect upon resumption. Alternatively, this verification step can be carried out when the recharge is triggered or at any time before the threshold SL is reached.

[0036] If the ambient temperature is lower than T1, during the second phase of the recharging session, after the threshold SI has been exceeded, the recharging device maintains, at a step 23, the control of the recharging current setpoint in accordance with the configuration of the CRI setpoint until the end of the recharging session.

[0037] If the ambient temperature is equal to or greater than T1, during the second phase of the recharging session, after exceeding the threshold SI, the recharging device, at a step 24, controls a recharging instruction CR2. The invention detects the possibility of a heat stroke effect upon resuming in this high heat situation. The method therefore reduces the value of the current setpoint compared to the CRI setpoint to avoid this unpleasant situation. According to a variant, preferably the CR2 setpoint is configured at a value which is a function of a predetermined reduction coefficient k according to the following relationship: CR2=k*CRl, with k between 0.2 and 0.8. Preferably, k is equal to 0.6. This is an optimal parameter for avoiding overheating upon resumption and maintaining a satisfactory recharge time. The CR2 setpoint is a current limitation setpoint having the effect of reducing the setpoint compared to situations with an ambient temperature lower than TL. The CR2 recharge setpoint is maintained until the end of the recharge session. The value of the reduction coefficient k has the effect of reducing the temperature in the battery cooling circuit, in return for a longer recharge time.

[0038] Finally, if the end of recharging is detected, the method ends at step 25. Then, when the road is resumed, the thermal regulation system of the vehicle changes configuration and allows an exchange of calories between the cooling circuit of the battery and the cooling circuit in which the radiator of the vehicle is located. Thanks to the invention, the effect of heat stroke is avoided due to a reduction in the recharging current triggered during an environmental temperature above 40° Celsius and during the operation of a fast recharging mode.

[0039] [Fig. 3] is a graph illustrating the control of the charging current according to the invention during a fast charging session. Three charging situations are shown taking place under distinct external environmental temperature conditions. The curve identified by the square-shaped symbols corresponds to a temperature of 35°C. This curve complies with the CRI setpoint. The curves identified by the triangular and round symbols correspond respectively to temperatures of 40°C and 45°C and comply with the CR2 setpoint. These two curves overlap because the charging current control is identical in these situations. The charging session includes the first phase during which the charging current is between 300A and 350A as can be seen on the y-axis. This charging current value is identical for the three situations.When the temperature is above 40°C, for the triangle and circle curves, a limitation of the charging current is observed in the second phase, from a state of charge of 60%, in accordance with a decrease in the value of the charging current according to the coefficient k, here to a value of 0.6. For the square curve, this limitation is not controlled because the temperature is below 40°C.

Claims

Claims

1. Method for recharging a traction battery (3) for a rechargeable electrified vehicle (1) by means of a charging terminal (7) in which a predetermined charging mode is configured determining a first charging current setpoint CRI for controlling the terminal (7), characterized in that it comprises the following successive steps during a charging session controlled according to said charging mode: - Controlling a first charging phase (20) controlled by the first current setpoint CRI as long as the state of charge of the battery is lower than a predetermined state of charge threshold (SI), - Controlling a second charging phase when the state of charge is higher than said state of charge threshold (SI) comprising controlling the charging current (23; 24) as a function of the temperature of the external environment (T) of the vehicle relative to a predetermined temperature threshold (Tl).

2. Method according to claim 1, characterized in that the control of the recharging current (23), during the second recharging phase, is controlled by the first current setpoint CRI if the environmental temperature (T) is lower than said temperature threshold (Tl), and when the environmental temperature (T) is higher than or equal to said temperature threshold (Tl), the control of the recharging current (24) is controlled by a second recharging current setpoint CR2 having a value which is a function of a predetermined reduction coefficient k according to the following relationship: CR2=k*CRl, with k between 0.2 and 0.

8.

3. Method according to claim 2, characterized in that the second current setpoint CR2 is a setpoint for limiting the maximum value of the recharging current.

4. Method according to any one of claims 1 to 3, characterized in that the first CRI setpoint is configured to control a continuous type recharge current having a value greater than 100 amperes until a level between 75% and 85% of the total capacity of the battery is reached.

5. Method according to any one of claims 1 to 4, characterized in that the state of charge (SOC) threshold is between 40% and 80% of the total battery capacity (3).

6. Method according to claim 5, characterized in that the state of charge threshold (SI) is equal to approximately 60% of the total capacity of the battery (3).

7. Method according to any one of claims 1 to 6, characterized in that said temperature threshold (Tl) is equal to approximately 40° Celsius.

8. Device for controlling the charging current (4) of a traction battery (3) for a rechargeable electrified vehicle (1) in which a predetermined charging mode is configured by means of a charging terminal (7) determining a first charging current setpoint CRI for controlling the terminal (7), comprising a means for measuring the temperature (T) of the environment outside the vehicle, a means for measuring the state of charge of the battery (3), characterized in that it is configured to implement the charging method according to any one of claims 1 to 7.

9. Rechargeable electrified vehicle (1) comprising a traction battery (3) and a device for controlling the recharging current (4) of said battery (3) according to claim 8.

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