METHOD FOR THE THERMOREGULATION OF AN ELECTRIC OR HYBRID VEHICLE BATTERY, COMPRISING AN ALTERNATING VOLTAGE CYCLE

Abstract

The invention relates to a method for thermoregulating a battery of an electric or hybrid vehicle. The battery includes a temperature sensor. The method comprises the following steps for an alternating voltage cycle: - a measurement step (E1) of the battery temperature by the temperature sensor; - a first step (E2) and a second step (E3) of applying voltage to the battery, respectively, to a first voltage value and a second voltage value, respectively, for a first predetermined duration and a second predetermined duration, respectively, during the alternating voltage cycle when the measured temperature value is lower than a predetermined temperature value. Thus, the battery can be heated. Figure 1

Description

Title of the invention: METHOD FOR THE THERMOREGULATION OF A BATTERY OF AN ELECTRIC OR HYBRID VEHICLE, INCLUDING AN ALTERNATING VOLTAGE CYCLE

[0001] The invention relates to electric vehicles, that is to say, those equipped with at least one battery for storing electrical energy intended for their propulsion. This includes vehicles with a single means of electric propulsion, as well as hybrid vehicles incorporating at least one mode of electric propulsion.

[0002] French patent application FR3011132 describes a battery heating device. The device is configured to be switched between a battery discharge phase and a battery charge phase. The device includes a temperature and battery state of charge control element that triggers the charge or discharge phase so as to heat the battery by Joule heating until the battery temperature reaches a predetermined target temperature.

[0003] However, when the battery is already fully charged, such a process cannot be used without causing damage to the battery or without limiting the stress on the battery during charging, thus hindering the heating of the battery.

[0004] The objection of the present invention is to remedy this drawback and to thermoregulate the battery more effectively.

[0005] To achieve this objective, the invention proposes a method for thermoregulating an electric or hybrid vehicle battery, the battery comprising a temperature probe, the method comprising the following steps for an alternating voltage cycle: - a step of measuring a battery temperature value using the temperature probe; - a step of putting the battery into voltage at a first predetermined electrical voltage value for a first predetermined duration included during the alternating voltage cycle when the measured temperature value is less than a predetermined temperature value; - a step of putting the battery into voltage at a second predetermined electrical voltage value for a second predetermined duration included during the alternating voltage cycle when the measured temperature value is lower than the predetermined temperature value.

[0006] Such a process maintains the battery at a temperature level so that the battery can be used, particularly in cold weather when the battery is under stress. This occurs during vehicle acceleration, regardless of the battery's charge level. Furthermore, it increases the power dissipated by Joule heating within the battery, eliminating the need for an external battery heating system.

[0007] Advantageously, the first predetermined electrical voltage value is greater in absolute value than the second predetermined electrical voltage value.

[0008] Advantageously, with respect to a predetermined reference voltage value, the first electrical voltage value is negative, the second predetermined electrical voltage value being positive.

[0009] This allows the battery to be used in such a way that the energy received by the battery during an alternating voltage cycle is globally zero.

[0010] Advantageously, the first predetermined duration is shorter than the second predetermined duration.

[0011] The ratio between the second predetermined voltage value and the first predetermined voltage value is chosen such that the first predetermined duration drawing on the battery is shorter than the second predetermined duration by a factor equal to that of the voltage values. Thus, the energy received by the battery is equal to the energy supplied by the battery, while ensuring that the power supplied by the battery is greater than the power received by the battery.

[0012] Advantageously, the alternating voltage cycle has a predetermined duration comprising the first predetermined duration and the second predetermined duration, the duration of the alternating voltage cycle being less than or equal to 10s.

[0013] Advantageously, the ratio between the second predetermined electrical voltage value and the first predetermined electrical voltage value is less than or equal to 0.9.

[0014] Advantageously, the ratio between the first predetermined duration and the second predetermined duration is less than or equal to 0.9.

[0015] Advantageously, the first predetermined voltage value and the second predetermined voltage value are between 2V and 5V.

[0016] The invention also relates to a computer program comprising program code instructions for executing the steps of the process defined as above, when the program is running on a computer.

[0017] The invention further relates to an electric or hybrid vehicle comprising: - a battery; - a control unit electronically connected to the battery, the control unit comprising means for acquisition, processing by software instructions stored in memory as well as control means required for the implementation of the computer program defined as above.

[0018] In practice, the electronic control unit is a battery management unit, also called a BMS for "Battery Management System". The battery management unit is already commonly used in hybrid or electric vehicles.

[0019] Thus, the process defined as above is easy to implement in the existing installation in the vehicle, further increasing the thermoregulation capabilities of the battery.

[0020] The invention will be further detailed by describing non-limiting embodiments, and based on the attached figure illustrating one embodiment of the invention, in which: - [Fig. 1] illustrates a flowchart representing the steps of a thermoregulation process for an electric or hybrid vehicle battery, according to an embodiment of the invention.

[0021] According to the invention, an electric or hybrid vehicle includes a battery. In practice, the battery is of the lithium-ion type, comprising at least one battery cell, in particular of the NMC (Nickel-Manganese-Cobalt) type.

[0022] The battery has an internal resistance, the value of the internal resistance being for example equal to 0.5mOhms.

[0023] The battery includes a temperature probe configured to measure a temperature value of the battery. For example, the temperature probe is located on the battery cell.

[0024] A flowchart of a propulsion method for an electric or hybrid vehicle is illustrated in [Fig.1], according to an embodiment of the invention, steps of the method being described below.

[0025] In a measurement step El, a temperature value of the battery is measured by the temperature probe.

[0026] In a power-up step E2, the battery is powered at a first predetermined electrical voltage value for a first predetermined duration included during the alternating voltage cycle when the measured temperature value is less than a predetermined temperature value.

[0027] The predetermined temperature value is preferably equal to 15°C.

[0028] For example, the first predetermined electrical voltage value, considered in relation to a predetermined reference voltage value, for example equal to 4.3V, is equal to -0.1V.

[0029] In a power-up step E3, the battery is powered at a second predetermined electrical voltage value for a second predetermined duration included during the alternating voltage cycle when the measured temperature value is lower than the predetermined temperature value.

[0030] For example, the second predetermined electrical voltage value, considered in relation to the reference voltage value, is equal to 0.05V.

[0031] In practice, the first predetermined electrical voltage value is greater in absolute value than the second predetermined electrical voltage value. Furthermore, the first predetermined electrical voltage value is negative while the second predetermined electrical voltage value is positive.

[0032] Preferably, the first predetermined duration is shorter than the second predetermined duration. To illustrate the examples above, the first predetermined duration extends over 0.5 s and the second predetermined duration extends over 1 s.

[0033] Generally, a first ratio between the second predetermined electrical voltage value and the first predetermined electrical voltage value is less than or equal to 0.9. Furthermore, a second ratio between the first predetermined duration and the second predetermined duration is less than or equal to 0.9. The first ratio and the second ratio are advantageously equal.

[0034] Thus, in the case where the maximum current value acceptable by the battery is less than or equal to 200A, the average power value dissipated by the battery is equal to 20W while the average power value dissipated by the battery is limited to 10W in the usual case where the first electrical voltage value and the second electrical voltage value are equal, for example, to 0.05V.

[0035] The alternating voltage cycle has a predetermined duration comprising the first predetermined duration and the second predetermined duration, the duration of the alternating voltage cycle being less than or equal to 10s, or even less than or equal to 1ms.

[0036] The alternating voltage cycle typically includes energizing the battery to the first predetermined electrical voltage value followed by energizing the battery to the second electrically predetermined voltage value.

[0037] Preferably, the first predetermined voltage value and the second predetermined voltage value are between 2V and 5V.

Claims

Demands

1. Method for thermoregulating an electric or hybrid vehicle battery, the battery comprising a temperature probe, the method comprising the following steps for an alternating voltage cycle: - a step of measuring (E1) a temperature value of the battery by the temperature probe; - a step of energizing (E2) the battery to a first predetermined electrical voltage value for a first predetermined duration included during the alternating voltage cycle when the measured temperature value is less than a predetermined temperature value; - a step of energizing (E3) the battery to a second predetermined electrical voltage value for a second predetermined duration included during the alternating voltage cycle when the measured temperature value is less than the predetermined temperature value.

2. A method according to claim 1, characterized in that the first predetermined electrical voltage value is greater in absolute value than the second predetermined electrical voltage value.

3. A method according to claim 1 or 2, characterized in that, with respect to a predetermined reference voltage value, the first predetermined electrical voltage value is negative, the second predetermined electrical voltage value is positive.

4. A method according to any one of claims 1 to 3, characterized in that the first predetermined duration is shorter than the second predetermined duration.

5. A method according to any one of claims 1 to 4, characterized in that the alternating voltage cycle has a predetermined duration comprising the first predetermined duration and the second predetermined duration, the duration of the alternating voltage cycle being less than or equal to 10s.

6. A method according to any one of claims 1 to 5, characterized in that the ratio between the second predetermined electrical voltage value and the first predetermined electrical voltage value is less than or equal to 0.

9.

7. A method according to any one of claims 1 to 6, characterized in that the ratio between the first predetermined duration and the second predetermined duration is less than or equal to 0.

9.

8. A method according to any one of claims 1 to 7, characterized in that the first predetermined voltage value and the second predetermined voltage value are between 2V and 5V.

9. Computer program comprising program code instructions for carrying out the steps of the process according to any one of claims 1 to 8, when the program is running on a computer.

10. Electric or hybrid vehicle comprising: - a battery; - a control unit electronically connected to the battery, the control unit comprising means for acquisition, processing by software instructions stored in memory and control means required for the implementation of the computer program according to claim 9.

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