FR2978702A1 - Method for cooling electric battery of e.g. electric car, involves utilizing performance information and/or power consumption information to determine heat power information, and estimating duration of cooling step - Google Patents

Abstract

The method involves utilizing performance information of a cooling device (1) and/or power consumption information of the cooling device to determine heat power information of a cooling step application. Duration of a cooling step is estimated using the heat power information of the cooling step application, where the estimation step utilizes current temperature information of an electric battery (3), desired temperature information of the battery, thermal information of inertia of the battery and/or heat exchange information between the battery and an external environment. Independent claims are also included for the following: (1) a data recording medium including a set of instructions to perform a method for controlling an electric battery (2) a cooling device (3) a computer program including a set of instructions to perform a method for controlling an electric battery.

Description

The invention relates to a method for cooling an electric battery, in particular an electric or hybrid electric vehicle electric battery. The invention also relates to a cooling device implementing such a method. The invention also relates to a data storage medium readable by a computer on which is recorded a computer program comprising computer program code means for implementing the steps of such a method. The invention finally relates to a computer program comprising computer program code means adapted to the execution of steps of such a method, when the program is executed on a computer. The invention also relates to a motor vehicle comprising a cooling device according to the invention.

Managing the thermal of the electric battery is one of the major issues of electric and hybrid vehicles. Generally, an electric vehicle requires cooling phases of its battery, otherwise the latter limit (at high temperature) its power, via its computer, to prevent damage.

Moreover, the cooling of the battery requires energy consumption and as the energy is linked to the autonomy in the context of electric vehicles, it is appropriate to take advantage of battery charging phases to implement a phase cooling the battery. Thus, during the cooling phase, the network energy can be used to cool the battery and not to use the electrical energy contained in the battery.

Document US 20100013648 A1 discloses a system for identifying batteries that can be used after recharging, depending on the cooling time of the latter. A bright display is activated when charging is complete. Then, a timer switches on and the battery is left idle for cooling. During this phase, a light is on to prohibit the use of the battery. After a certain number of hours, a new LED is lit to indicate that the battery has cooled down enough and can be used. Thus, a user can simply choose a sufficiently cool battery in a storage location comprising several batteries.

Such a system provides a solution for the application mentioned in US 20100013648 A1, but a problem remains for the applications contemplated herein. At a given moment, we do not know when a given battery can be used.

The object of the invention is to provide a method of cooling a battery obviating the disadvantages mentioned above and improving the known methods of the prior art. In particular, the invention proposes a simple and effective method for improving the logistical management of cooling of the batteries in a charging station.

According to the invention, the method of cooling an electric battery of a motor vehicle comprises a cooling step and a step of estimating the duration of the cooling step in which a heating power information item is used. in the cooling step, a performance information of a cooling device and / or electrical consumption information of the cooling device being used to determine the heating power information implemented in the cooling step.

In the step of estimating the duration, it is possible to use: a current temperature information of the battery, and / or a desired temperature information of the battery, and / or a thermal inertia information of the battery. battery, and / or - A heat exchange information between the battery and an external environment.

The cooling step can be implemented only when the motor vehicle is connected to an external electrical power source, such as an electric charging terminal.

It is possible to implement a step of electrically recharging the battery during the cooling step.

In the step of estimating the duration of the cooling step, Joule effect power dissipation information may be used in the battery during the recharging step.

The duration of the cooling step can be determined according to the formula: MX Cp X d = Pfroid + Hot + Rth x ATbat, eYt with: M the mass of the battery, Cp a constant representing the specific heat of the battery , 25 Warm a power heating the battery, Pfroid a power cooling the battery, Rth a heat exchange coefficient, ATbat, ext the temperature difference between the battery and an external medium. The step of estimating the duration of the cooling step can be carried out during a step of charging the battery.

The invention also relates to a data storage medium readable by a computer on which is recorded a computer program comprising computer program code means implementing the steps of the method defined above.

According to the invention, a device for cooling an electric battery of a motor vehicle comprises material and / or software means capable of implementing the method defined above.

According to the invention, an electric or hybrid motor vehicle comprises a cooling device defined above.

According to the invention, a computer program comprises computer program code means adapted to execute steps of the method defined above, when the program is executed on a computer.

The appended drawing shows, by way of example, an embodiment of a cooling device according to the invention and an embodiment of a cooling method according to the invention. Figure 1 is a diagram of an embodiment of a cooling device according to the invention.

FIG. 2 is a diagram of a logic architecture for calculating a cooling time of a battery according to an embodiment of the cooling method. An embodiment of a cooling device 1 is described below. Fig. 1. The cooling device mainly comprises a cooling element 4 and a control unit 2 of the cooling element. The cooling device is intended to cool an electric battery of a motor vehicle, including the electric battery powering a drive motor of a hybrid or electric motor vehicle. The cooling device can be part of the motor vehicle.

The cooling element 4 may be of the type ensuring cooling by air (Peltier system, air conditioning system) or by water (water circuit equipped with a pump and a fan unit, with radiator for example).

The connection between the battery and the control unit is for example provided via a communication network (CAN network for example). A computer linked to the battery sends a certain amount of information to the control unit, particularly preferably the temperature of the battery. According to information received by the control unit, the latter controls the activation and operation of the cooling element. In particular, the cooling element is activated when the temperature of the battery is too high and deactivated when the temperature of the battery is sufficiently low.

Preferably, in a step of cooling the battery, the control unit estimates or determines, particularly by calculation, the cooling time required for the battery temperature to reach a target temperature or a predetermined temperature.

In particular, the determination or estimation is made according to the electrical power consumed on the network, the efficiency of the cooling means and the temperatures (outside the battery and the battery). This time information can be displayed or transmitted for information to the user. In particular, the time information can be transmitted (via the CAN network for example) to a dashboard of the vehicle or to an electric charging station.

The cooling device, in particular the control unit, comprises all the hardware and / or software means making it possible to implement the cooling method that is the subject of the invention. In particular, the cooling device comprises hardware and / or software means making it possible to implement each of the steps of the cooling method that is the subject of the invention. These means may include computer programs. The cooling device can in particular comprise: a means for determining the temperature of the battery, and / or a means for determining the temperature of the external medium, in particular for determining the temperature of the ambient air surrounding the battery and the motor vehicle, and / or a means for determining the electric power supplied by a charger recharging the battery, and / or a means for measuring the electrical supply voltage of the cooling element, and / or a means for measuring the electric power supplied to the cooling element.

The cooling device may also advantageously comprise a display means. Alternatively or additionally, the cooling device comprises a data transmission means for transmitting, in particular to another system of the motor vehicle, a cooling time information.

An exemplary architecture of the control unit is described below with reference to FIG.

The control unit comprises a first module 11 for estimating the energy losses during the electric charge of the battery. This module may for example contain a numerical model for determining energy losses, including Joule losses in the battery, from the charging electric power of the battery P_charge and the current temperature of the battery Tbat. The charging power may depend on the charge level of the battery.

The control unit comprises a second module 12 for estimating the efficiency of the cooling element. This module may for example contain a numerical model for determining the efficiency from the temperature of the external environment Text, the supply voltage of the cooling element V supply and the current temperature of the battery Tbat.

At a multiplication operator 14, the efficiency is multiplied by the electrical power supplied to the cooling element. At the output of this operator, a heating power of cooling of the battery is obtained.

At an addition operator 15, the energy losses during the electric charge of the battery and the cooling heat capacity of the battery are added. At the output of this operator, we obtain the net heating power to change the temperature of the battery. Complementarily, it is still possible to calculate this net heating power, take into account the change in the temperature of the battery by heat transfer with the external environment, because of the temperature difference between the battery and the external environment.

In parallel with these calculations, the difference in temperature between the current temperature of the battery Tbat and the predetermined temperature that is to be obtained at the end of the cooling step is calculated at the level of a subtraction operator 13. these differences at the level of a multiplication operator 16. At the output of this multiplication operator 16, the product of the difference in temperature, the mass of the battery and the mass heat of the battery is obtained.

The product determined above and the net heating power attack a division operator 17 for outputting a signal representative of the cooling time.

The embodiment of the architecture described above makes it possible to describe the thermal dynamics of the battery which can also be described by the following expression: M x C, X d ~ - Pfroid + Chaud + Rth X ATbat / ext With: M the mass of the battery, Cp the mass specific heat of the battery, the hot power heating the battery, Pfroid the power cooling the battery, Rth a heat exchange coefficient between the battery and the external environment, ATbat, ext the difference of temperature between the battery and the outside. It should be noted that, in the architecture of Figure 2, the term: xth xATbat, ext is neglected, because little influence.

In general, the term Rth x L \ Tbat, ezt is weak in front of the Pchaud and Pfroid powers, especially if the battery is well insulated (for other reasons). We can further simplify the expression, assuming the constant terms. We then obtain MxCpxAT At = Pfroid + P hot with: 10 dT = Tbat - Tbat target OT At the cooling time. In summary, in order for the battery temperature to drop, starting from the temperature Tbat and reaching the target temperature Tbat, a duration calculated by the preceding formula is required. One of the problems of time estimates is the fluctuation of these with certain terms, which makes them unconvincing in the eyes of users. However, the advantage of the cooling time estimation according to the invention is that the parameters that are used are fairly stable in a step of charging or recharging the battery. Indeed, the powers used to recharge the battery are almost constant during this step (unlike a training phase of the motor vehicle where one can go from a zero drive power to a maximum drive power in a few seconds, and thus where one can go from a very low level of losses to a level of losses of the order of several kilowatts). In the case of a charging step, the information used to define the cooling time is very stable (power load, cooling power and cooling device efficiency). The duration estimate is therefore accurate and reliable.

The cooling power itself is fairly constant also, whether with air or water cooling.

In the case where the cooling of a battery of an electric or hybrid vehicle is ensured only in an electric charging step, an estimate of the cooling time, that is to say the cooling time remaining, constitutes, with an estimate of the remaining cooldown, important information for the user. From the point of view of the user, this information facilitates, for example, a better use of the waiting time remaining for the end of recharging or cooling the battery. In a charging station, this remaining time information optimizes the charging station occupancy time.

For conventional loads (on home networks), the powers (or losses) that cause the battery to overheat are low and can be neglected to simplify the calculation algorithm. This simplification can be done even more if the precision requested is not very fine (10 min for example). Such precision remains quite acceptable for durations of several hours. For the same reasons, one can also consider a constant return.

The cooling device described above makes it possible to implement an embodiment of a cooling method in which a cooling step and a step of estimating or determining the duration of the cooling step are implemented. . The estimation step is therefore performed during the cooling step or before the cooling step. In the case where the estimation step is performed during the cooling step, the result of this estimation step constitutes a cooling time information remaining until the battery reaches a target value. Preferably, the estimation step is repeated at regular intervals throughout the cooling step. The duration information is intended to be displayed to inform the user, possibly after being transmitted to another system of the motor vehicle.

In the step of estimating the duration, it is possible to use: a current temperature information of the battery, and / or a desired temperature information of the battery, and / or a calorific power information implemented. in the cooling step, and / or - thermal inertia information of the battery, and / or - heat exchange information between the battery and an external medium.

It is also possible to use: - a yield information of a cooling device (1), and / or - an electrical consumption information of the cooling device, for determining the heating power information implemented in the step of cooling.

Preferably, the cooling step is implemented only when the motor vehicle is connected to a source of external electrical energy, such as an electric charging terminal. Advantageously, an electric charging stage of the battery is implemented. during the cooling step. In this case, it is also possible to estimate or determine a time remaining until the battery is electrically recharged to a given level and transmit it to the user, in particular by means of a display device. It is also possible to transmit to the user only the longest duration of remaining charge and cooling remaining.

This data of remaining cooling times or remaining recharge can also be used by battery charging station systems to improve their logistical management, including improving the physical flow of batteries and system availability. 15

Claims (2)

1. A method of cooling an electric battery (3) of a motor vehicle comprising a cooling step and a step of estimating the duration of the cooling step in which a heat power information setting is used in the cooling step, a cooling device performance information and / or cooling device power consumption information being used to determine the heating capacity information implemented in the cooling step . 2. Cooling method according to the preceding claim, characterized in that, in the step of estimating the duration, is used: - a current temperature information of the battery, and / or - a desired temperature information of the battery, and / or - thermal inertia information of the battery, and / or - heat exchange information between the battery and an external medium. 7. Cooling method according to one of the preceding claims, characterized in that it implements the cooling step only when the motor vehicle is connected to a source of external electrical energy, such as an electric charging terminal. 8. Cooling method according to the preceding claim, characterized in that it implements a step of charging the battery electrically during the cooling step. Cooling method according to the preceding claim, characterized in that, in the step of estimating the duration of the cooling step, use is made of power dissipated by Joule effect in the battery during the recharging step . 6. A method of cooling according to one of the preceding claims, characterized in that determines the duration of the cooling step according to the formula: MX Cp X d ~ = Pfroid + Chaud + Rth x ATbat, eYt 10 with: M the mass of the battery, Cp a constant representing the specific heat of the battery, Heating a power heating the battery, Pfroid a power cooling the battery, 15 Rth a heat exchange coefficient, ATbat, ext the temperature difference between the battery and an external environment. 7. Cooling method according to one of the preceding claims, characterized in that the step of estimating the duration of the cooling step is implemented during a step of charging the battery. 8. Computer-readable data recording medium on which is recorded a computer program comprising computer program code means for implementing the steps of the method according to one of the preceding claims. 9. Device (1) for cooling an electric battery (3) of a motor vehicle, characterized in that it comprises material means (2, 11, 12, 13, 14, 15, 16, 17) and / or software capable of implementing the method according to one of claims 1 to 7. 10. Electric or hybrid motor vehicle comprising a device (1) for cooling according to claim 9. 11. Computer program comprising a code means of computer program adapted to the execution of steps of the method according to one of claims 1 to 7, when the program is executed on a computer.