Method for detecting malfunctions in a vehicle comprising an electric battery

Abstract

The invention relates to a method for detecting a malfunction in the cooling system (112) of a vehicle (1) comprising an electric battery (11) cooled by means of said cooling system (112), the cooling system comprising a refrigerant cooled by an evaporator (132) of an air conditioning circuit (13), the method comprising the steps of: (E1) Acquiring a battery temperature (T1) by means of a first temperature sensor (111); (E2) Acquiring a refrigerant temperature (T2) by means of a second temperature sensor (131); and (E4) Comparing the battery temperature with the refrigerant temperature, a malfunction in the vehicle's cooling system being detected based on the result of the comparison (D_Dis, D_Conf). Figure for the abstract: Fig. 1

Description

Title of the invention: Method for detecting malfunctions in a vehicle comprising an electric battery. Technical field

[0001] The invention is in the field of automobiles, more particularly it relates to the field of diagnostic methods for vehicles comprising an electric battery whose cooling is ensured by the air conditioning system of the passenger compartment. Previous technique

[0002] The presence of high-voltage batteries in current vehicles, particularly as traction batteries in electric, hybrid, and plug-in hybrid vehicles, necessitates the use of complex cooling systems whose proper functioning is crucial to the performance and operation of the vehicles they equip. Indeed, the optimal operating range of an electric battery is typically between 25°C and 40°C; below this temperature, the vehicle's range can be drastically reduced, while above it, the battery may be unable to deliver its full power or could even suffer irreversible damage. An unsuitable battery temperature can also affect the vehicle's charging time.It is therefore essential to have a cooling system capable of precisely maintaining the battery within a temperature range suitable for its proper functioning, avoiding both excessively high and excessively low temperatures.

[0003] It is particularly known for this purpose to use a battery cooling system comprising a cooling element of a battery module, this cooling element being mounted in parallel with an evaporator of an air conditioning circuit intended for cooling the passenger compartment (see for example publication FR 3 117 955 Al which describes such a system).

[0004] However, in the event of a malfunction in the passenger compartment cooling system, for example, due to a refrigerant leak, vehicle performance may be affected because of inadequate cooling of the traction battery. Such a malfunction can be very difficult to diagnose. Indeed, while automatic diagnostic methods for the cooling system exist, they can only detect major malfunctions. For example, a complete rupture of a refrigerant line resulting in a sudden and significant leak would be detectable by temperature sensors, but a loss of cooling system power due to a minor leak would have no effect. Over a long period, this malfunction could remain undetected by diagnostic systems. Indeed, the complexity of these systems, as well as the nature of the refrigerants used, makes it very difficult to measure, directly or indirectly, the quantity of refrigerant in the air conditioning system.

[0005] The consequence of this is that, in practice, air conditioning system malfunctions are most often only detected by vehicle occupants when the vehicle's interior is not adequately cooled despite the air conditioning being activated. For these reasons, this type of diagnostic method, depending on its settings, may either detect a fault where none exists (false positives) or fail to detect a fault where one actually exists (false negatives).

[0006] Beyond the obvious shortcomings of a diagnostic system left to the vehicle's occupants, another major problem is that occupants can only detect a malfunction when the air conditioning system is used to cool the passenger compartment, i.e., during periods of intense heat. However, when the air conditioning system is used for battery thermal management, the existence of a malfunction is unacceptable due to its effects on vehicle operation. These effects on vehicle operation (loss of power, reduced range, increased charging time, etc.) are also very difficult to attribute to a thermal comfort feature such as an air conditioning system.

[0007] One object of the invention is therefore to provide a method for detecting malfunctions suitable for a battery cooling system using the vehicle's air conditioning circuit as described above. Summary of the invention

[0008] To this end, the present invention proposes, according to a first aspect, a method for detecting a malfunction in the cooling system of a vehicle comprising an electric battery cooled by means of said cooling system, the cooling system comprising a refrigerant fluid cooled by an evaporator of an air conditioning circuit, the method comprising the steps of: - Acquisition of battery temperature using a first temperature sensor; - Acquisition of the refrigerant temperature using a second temperature sensor; and - Comparison of the battery temperature with the refrigerant temperature, a malfunction of the vehicle's cooling system being detected based on the result of the comparison. Such a process is particularly advantageous because it allows the diagnosis of the vehicle's battery cooling system without requiring the installation of additional components in the vehicle.

[0009] In addition to the characteristics mentioned in the preceding paragraph, the process according to the invention may have one or more additional characteristics from among the following, considered individually or according to all technically possible combinations.

[0010] According to one embodiment, the step of comparing the temperature of the battery with the temperature of the refrigerant includes determining a difference between the temperature of the battery and the temperature of the refrigerant.

[0011] This embodiment is particularly advantageous compared to simply monitoring only one of the two temperatures since it avoids cases of false negatives that can occur when the climatic conditions outside the vehicle allow passive cooling of the battery without the cooling system being fully functional.

[0012] According to an embodiment compatible with the previous embodiment, the method further includes a step of determining an activation state of the cooling system as a function of the battery temperature, and in which the step of comparing the battery temperature with the temperature of the refrigerant is implemented when the activation state of the cooling system indicates that the cooling system is active.

[0013] This makes it possible in particular to lighten the computational load on the processing unit and to reduce the energy consumption of the vehicle by only carrying out the complex temperature comparison operations when it is really relevant.

[0014] According to an alternative embodiment of the previous alternative embodiment, the activation state of the cooling system is determined based on the battery temperature, the cooling system being active when the battery temperature exceeds a predetermined threshold.

[0015] This embodiment of determining the activation state of the cooling system is particularly advantageous because it is both simple to implement and does not require any additional information beyond that already acquired by the malfunction detection system.

[0016] According to an alternative embodiment of the previous alternative embodiment, the predetermined threshold is dependent on the outside temperature of the vehicle.

[0017] This makes it possible to avoid false positives in determining the activation state of the cooling system, particularly when the outside temperature is low; in this case, passive air cooling of the battery External factors could lead the process to conclude that the cooling system is activated when this is not the case.

[0018] According to an embodiment compatible with previous embodiments, the step of comparing the temperature of the battery with the temperature of the refrigerant is carried out after a predetermined delay from the moment when the activation state of the cooling system indicates that the cooling system is active.

[0019] In this way, the cooling system has time to lower its temperature in order to avoid a false detection, indeed, when it is activated, the air conditioning circuit is at ambient temperature, this delay thus allows this phenomenon to be taken into account.

[0020] According to an embodiment compatible with the previous embodiments, the method further includes a step of issuing an alert when the presence of a malfunction is detected.

[0021] This allows the driver of the vehicle to become aware of a defect and therefore to take the necessary measures to correct it.

[0022] According to an embodiment compatible with the previous embodiments, the method further includes a step of acquiring an outside temperature of the vehicle by means of a third temperature sensor, as well as a step of comparing the temperature of the refrigerant acquired to temperatures of the refrigerant previously acquired under similar conditions of battery temperature and outside temperature.

[0023] According to a second aspect, the invention also proposes a system for detecting a malfunction in the cooling system of a vehicle comprising an electric battery cooled by means of said cooling system, said cooling system comprising a refrigerant, the refrigerant being cooled by an evaporator of an air conditioning circuit intended for cooling a passenger compartment of the vehicle, the malfunction detection system comprising: - A first temperature sensor configured to acquire a battery temperature; - A processing unit; - A second temperature sensor, configured to acquire the temperature of the refrigerant, The processing unit is configured to implement a method for detecting a malfunction of the vehicle's cooling system according to the first aspect.

[0024] According to a third aspect, the invention also proposes a motor vehicle comprising a system for detecting a malfunction of a vehicle according to the second aspect. Brief description of the drawings

[0025] The invention will be better understood and other features, details and advantages will become clearer from the following description, given by way of non-limiting reason, and from the accompanying figures, given by way of example.

[0026] [Fig-1] Fig. 1 is an illustration of a cooling architecture for the implementation of the invention according to a first embodiment;

[0027] [Fig.2] The [Fig.2] is an illustration of a cooling architecture for the implementation of the invention according to a second embodiment;

[0028] [Fig.3] The [Fig.3] is a flowchart of the steps of a process according to the invention;

[0029] [Fig.4] Fig.4 is a curve representing a first set of data acquired by a malfunction detection system according to the invention

[0030] [Fig.5] Fig.5 is a curve representing a second set of data acquired by a malfunction detection system according to the invention

[0031] Identical references may be used in different figures when they refer to identical or comparable elements. Description of the implementation methods

[0032] An example of a motor vehicle 1 enabling the implementation of a method according to the invention is described in [Fig. 1]. The motor vehicle 1 comprises an electric battery 11 (or alternatively any other means of energy storage requiring a precisely controlled temperature) cooled by means of a cooling system 112 comprising a refrigerant. In particular, the cooling system 112 may be a cold plate inside which the refrigerant circulates, the cold plate being in contact with the battery 11. Alternatively, the refrigerant may circulate directly inside the battery 11. Similarly, if the battery is divided into a plurality of modules, each having its own cooling system, these modules may be networked.In this case, and to simplify the rest of the description, the cooling system network will be described as a single cooling system. The battery 11 also includes a temperature sensor 111 for measuring its temperature, denoted TL. This sensor can, for example, be placed on the surface of the cooling element to measure its temperature.

[0033] The motor vehicle 1 also includes an air conditioning circuit 13 for cooling the passenger compartment 14 of the vehicle. This air conditioning circuit 13 may include, in particular, a compressor, a condenser (not shown) and at less an evaporator 132 (responsible for cooling the passenger compartment 14), and a temperature sensor 131 for measuring the temperature, denoted T2, of the refrigerant circulating in the air conditioning circuit at the level of the cooling system 112. The temperature sensor 131 measuring the temperature T2 of the refrigerant can, for example, be a surface temperature probe positioned on the surface of the cooling system 112. This air conditioning circuit 13 is also connected to the cooling system 112 of the battery 11, for example by means of a fluid connection, the refrigerant of the air conditioning circuit 13 also circulating in the cooling system 112. In this way, when the battery 11 needs to be cooled, the compressor of the air conditioning circuit 13 can be controlled to circulate the refrigerant in the cooling system 112.

[0034] With further reference to [Fig. 1], the vehicle 1 may also include a processing unit 21 configured to implement the method for detecting a malfunction in the cooling system. For this purpose, the processing unit 21 comprises at least one processor, at least one memory, and various input / output interfaces, the interfaces enabling, in particular, the reception of the temperatures T1 and T2 acquired by the temperature sensors (111 and 131, respectively). Alternatively, as illustrated in [Fig. 2], the processing unit 21 may be an element external to the motor vehicle 1, such as a remote server connected to the vehicle via a data transfer network.

[0035] To perform the detection, a first step El of acquiring the temperature of the battery Tl is carried out using the first temperature sensor 111, this temperature being received by the processing unit 21. When the battery 11 is divided into a plurality of modules, each of these modules can be equipped with a dedicated temperature sensor; the plurality of measured temperature values ​​can then be aggregated to obtain a single temperature for the entire battery. To perform the aggregation, an average of the temperatures of all the modules can be calculated; alternatively, it is also possible to take the maximum temperature value or the minimum temperature value.This operation then amounts to having a "virtual" sensor measuring the aggregate temperature, so subsequently even when the type of battery used is a battery composed of several modules (or cells) the invention will be described as if the battery had only one temperature sensor (corresponding to the "virtual" sensor).

[0036] The transmission of the measured temperature between the temperature sensor 111 and the processing unit 21 can be carried out using a wired local area network embedded in the vehicle, such as a CAN network, or an Ethernet network. Alternatively, the first temperature sensor 111 can use means Wireless communication, for example with a suitable transmitter / receiver pair to exchange information using a known protocol such as Bluetooth, Wi-Fi, Zigbee, etc., is possible. Obviously, when the processing unit 21 is external to the vehicle, as is the case with a remote server, the first temperature sensor can be adapted to communicate directly with the remote server via a telecommunications network (such as 2G, 3G, 5G, etc.). Similarly, the sensor can be connected to a gateway shared by various vehicle devices via one of the aforementioned methods (wired or wireless), with the gateway itself communicating with the processing unit via a wireless telecommunications protocol.

[0037] Similarly, a step E2 of acquiring, by means of the second temperature sensor 131, the temperature T2 of the refrigerant circulating in the air conditioning circuit is implemented by the processing unit 21, which then receives the temperature T2 from the second temperature sensor 131. As is the case for the temperature T1 and the first temperature sensor 111, the transmission of the temperature T2 by the second sensor 131 can be carried out by means of a wired local area network embedded in the vehicle, such as a CAN network, or even an Ethernet network. Alternatively, the second temperature sensor 131 can use wireless communication means similar to those used by the first temperature sensor 111.Here too, when the processing unit 21 is external to the vehicle, as is the case when it is a remote server, the second temperature sensor can be adapted to communicate directly with the remote server via a telecommunications network (such as 2G, 3G, 5G etc.), as well as via the use of a gateway common to various on-board equipment of the vehicle, the second temperature sensor 131 being in this case connected to the gateway by a wired or wireless data link and the gateway itself being in communication with the processing unit 21 via a wireless telecommunications protocol.

[0038] In addition to acquiring the two temperatures T1 and T2 and directly processing the data, the temperature data can also be sent to a database in order to store a plurality of acquisitions, for example carried out at regular time intervals, in order to allow subsequent use of the acquired temperatures.

[0039] Then, when the temperature of the battery Tl and of the refrigerant Once T2 is acquired, the processing unit 21 implements a step E4 comparing the temperature of the battery T1 with the temperature of the refrigerant T2. In one embodiment, this comparison can be a calculation of the difference between the temperature of the battery T1 and the temperature of the refrigerant T2, but More advanced comparison methods can also be implemented. Depending on the comparison result, for example, when the difference between the two temperatures is less than a predefined threshold, the processing unit 21 determines that a malfunction has been detected. Since the difference between the two temperatures is defined as positive, the temperature of the refrigerant T2 is lower than the temperature of the battery T1. Such a threshold could, for example, be 15°C. This means that as long as the temperature of the refrigerant T2 is at least 15°C lower than the temperature of the battery T1, and preferably 20°C lower than the temperature of the battery T1, then the diagnosis is that the battery cooling is functioning correctly (D_Conf); otherwise, a malfunction has been detected (D_Dis).The predefined threshold against which the difference between the two temperatures is compared can be modified depending on the type of batteries used and their performance, particularly in terms of available power and the capacity of the cooling system.

[0040] In another embodiment, several acquisitions can be compared, again using a difference between the temperature T1 of the battery and the temperature T2 of the refrigerant, but based on an indicator and not just a single measurement of the difference between the temperatures. By indicator, we mean the result of applying a statistical method to a set of temperatures; the indicator can, for example, be the average of a number of the last acquired temperature measurements, the median, the mode, etc. In this case, as in that of observing the difference between the temperature of the refrigerant T2 and the temperature of the battery T1, the difference between the indicator calculated based on the temperatures of the refrigerant T2 and the indicator calculated based on the temperatures of the battery T1 can be observed to determine the state of the cooling system.The detection of a malfunction in the vehicle's battery cooling system is then carried out in the same way, by comparing this deviation to the predefined threshold.

[0041] In yet another alternative embodiment, a machine learning method can be implemented to compare one or more acquisitions of the battery temperature T1 and the refrigerant temperature T2, and on this basis, detect whether or not a malfunction is present. For example, the machine learning method used could be a support vector machine (SVM), a random forest of decision trees, a multi-layer perceptron, a fully connected neural network, a convolutional neural network, or a recurrent neural network. To achieve this, a database consisting of series of battery temperature values ​​and refrigerant temperature values, to which labels are associated, is used. previously determined indicators indicating the presence or absence of a malfunction may be used.

[0042] The process implemented by the processing unit may also, prior to the temperature comparison step E4, perform a step E3 to determine an activation state Cl of the cooling system 112. The result of determining the activation state Cl of the cooling system 112 conditions the implementation of step E4, which compares the temperature of the coil T1 with the temperature of the refrigerant T2. Step E4, comparing the temperature of the coil T1 with the temperature of the refrigerant T2, is implemented when the activation state Cl is met (Cl = T).

[0043] In a first embodiment, the activation state can be directly deduced from the cooling system controller, for example based on a control signal that the controller sends to actuators of the air conditioning circuit.

[0044] In an alternative embodiment, the activation state can also be determined indirectly by comparing the battery temperature Tl with a predetermined cooling trigger threshold SI. Such a threshold may be a predetermined fixed value, for example, 50°C, but it may also depend on the characteristics of the battery and / or the vehicle in question.

[0045] In a complementary embodiment, the SI threshold for triggering the cooling can also depend on the temperature outside the vehicle T_ext (acquired by means of a temperature sensor 101 mounted on the vehicle). This can, for example, be achieved by means of a predefined function associating a trigger threshold value SL with an outside temperature value. This also includes the use of an array of values ​​that associates each outside temperature value with a SI threshold for triggering the cooling.

[0046] When the activation state Cl of the cooling system 112 indicates that the cooling system is active, a time delay can be implemented to perform the step of determining the difference between the temperature of the coil T1 and the temperature of the refrigerant T2. This time delay begins after a predetermined period from the moment the activation state of the cooling system indicates that it is active. This predetermined period can be determined, in particular, based on the characteristics of the air conditioning circuit, in order to allow the latter time to begin producing cold. The period can, for example, be on the order of 10 seconds, preferably at least 30 seconds.

[0047] In one embodiment of the invention, when a malfunction is detected, an alert emitting step can be implemented by the processing unit. Such an alert can be carried out by means of an indicator light displayed on the dashboard of the The alert can be sent to the vehicle itself, but it's also possible to schedule a notification via an app on a device such as a smartphone. The driver can then receive the alert and have their vehicle checked at a garage. Alternatively, the alert can be sent directly to the vehicle manufacturer's after-sales service, which can then schedule an appointment for the owner to have their vehicle inspected.

[0048] Furthermore, similarly to the way temperatures T1 and T2 are stored in a database, the outside temperature T_ext acquired by means of the temperature sensor 101 can also be stored in the database and associated with the temperatures T1 and T2 acquired at the same time, for later use. In this case, an additional step of comparing the acquired refrigerant temperature with refrigerant temperatures previously acquired under similar coil and outside temperature conditions can be implemented. For this, it is possible, for example, to compare the current refrigerant temperature T2 and the coil temperature T1 with refrigerant temperature values ​​stored in the database and associated with an identical or substantially identical outside temperature (for example, within 1°C).Thus, if the current temperature of the refrigerant is significantly higher than the stored values, a malfunction can be identified.

[0049] To illustrate the implementation of the malfunction detection method, an example of acquired temperature data is shown in [Fig. 4] by two temperature-time curves. Curve T1 represents the evolution of the battery temperature values ​​T1 acquired during vehicle use, and curve T2 represents the evolution of the refrigerant temperature values ​​T2. According to the steps of the method described above, when the battery temperature T1 exceeds the trigger threshold SI (represented by the constant horizontal line), as is the case at the point with abscissa 22:40, the battery cooling system is activated.It is then observed that after a brief delay (approximately thirty seconds), the temperature T2 of the refrigerant drops sharply and shows a significant difference from the temperature of the battery T1 (approximately 15°C). This indicates, according to the comparison performed in step E4 of the process, that the cooling system is functioning correctly. A second occurrence of this same sequence of steps is also observed at the point with abscissa 23:00, for which the process also concludes that the cooling system is functioning correctly.

[0050] Figure 5 illustrates another case of the process, again showing the evolution of the battery temperature T1 and the evolution of the regenerating fluid temperature T2. The battery temperature here exceeds the SI threshold at point At an x-coordinate of 13:30, however, the temperature of the refrigerant T2 remains very close to the battery temperature T1 after this threshold is crossed, even if a difference is eventually observed between these two temperatures. The temperature curve T_Ext represents the ambient temperature in which the vehicle is operating and is approximately 15°C. This is a relatively cold temperature at which the battery could experience slight cooling simply from the vehicle's movement. In this case, the predefined threshold for the difference between the two temperatures T1 of the battery and T2 of the refrigerant, set for example at 15°C, is not reached. The system then concludes that there is a malfunction in the cooling system: the battery cooling is not operational and / or there is a lack of refrigerant in the circuit.

[0051] The described method makes it possible to characterize the proper functioning of the vehicle's cooling system, and in particular to detect power losses related to potential coolant leaks, which can lead to various faults such as loss of traction, hesitation, increased charging time, and ineffective air conditioning. It achieves this by relying not on direct observations of the battery or cooling system temperatures, but on observations of the temperature difference between these two components after the cooling system is activated. Furthermore, it makes it possible to monitor the evolution of this difference under similar conditions, in order to detect power losses in the air conditioning system before these power losses affect the cooling of the passenger compartment or the performance of the electric vehicle.

[0052] The invention relates to a method for detecting a malfunction in a vehicle as described above, and also to the system comprising an electric battery cooled by means of a cooling system, and a control unit (i.e., computing means such as an on-board computer, a microprocessor, or any equivalent computing means) configured to implement the described method. The invention also relates to a vehicle comprising such a system.

Claims

Demands

1. Method for detecting a malfunction of the cooling system (112) of a vehicle (1) comprising an electric battery (11) cooled by means of said cooling system (112), the cooling system comprising a refrigerant cooled by an evaporator (132) of an air conditioning circuit (13), the method comprising steps of: - (E1) Acquisition of a temperature of the battery (T1) by means of a first temperature sensor (111); - (E2) Acquisition of a temperature of the refrigerant (T2) by means of a second temperature sensor (131); and - (E4) Comparison of the temperature of the battery with the temperature of the refrigerant, a malfunction of the vehicle's cooling system being detected according to the result of the comparison (D_Dis, D_Conf).

2. A method for detecting a malfunction in the cooling system of a vehicle according to claim 1, wherein the step (E4) of comparing the battery temperature with the temperature of the refrigerant includes determining a difference between the battery temperature and the temperature of the refrigerant.

3. A method for detecting a malfunction of the cooling system of a vehicle according to any one of claim 1 or 2, further comprising a step (E3) of determining an activation state (Cl) of the cooling system (112) as a function of the battery temperature, and wherein the step of comparing the battery temperature with the temperature of the refrigerant is implemented when the activation state of the cooling system indicates that the cooling system is active (Cl = T).

4. A method for detecting a malfunction of the cooling system of a vehicle according to claim 3, wherein the activation state of the cooling system is determined as a function of the battery temperature, the cooling system being active when the battery temperature exceeds a predetermined threshold (SI).

5. A method for detecting a malfunction in the cooling system of a vehicle according to claim 4, wherein the predetermined threshold is dependent on the outside temperature of the vehicle.

6. A method for detecting a malfunction of the cooling system of a vehicle according to any one of claims 3 to 5, wherein the step (E4) of comparing the temperature of the battery with the temperature of the refrigerant is carried out after a predetermined delay from the moment when the activation state of the cooling system indicates that the cooling system is active.

7. A method for detecting a malfunction in the cooling system of a vehicle according to any one of claims 1 to 6, further comprising a step of issuing an alert when the presence of a malfunction is detected.

8. A method for detecting a malfunction of the cooling system of a vehicle according to any one of claims 1 to 7, further comprising a step of acquiring an outside temperature (T_Ext) of the vehicle by means of a third temperature sensor (101), as well as a step of comparing the temperature of the refrigerant acquired to temperatures of the refrigerant previously acquired under similar conditions of battery temperature and outside temperature.

9. A system for detecting a malfunction in the cooling system of a vehicle (1) comprising an electric battery (11) cooled by means of said cooling system (112), said cooling system comprising a refrigerant, the refrigerant being cooled by an evaporator (132) of an air conditioning circuit (13) intended for cooling a passenger compartment (14) of the vehicle, the malfunction detection system comprising: - A first temperature sensor (111) configured to acquire a temperature of the battery (T1); - A processing unit (21); - A second temperature sensor (131), configured to acquire a temperature of the refrigerant (T2),

10. The processing unit being configured to implement a method for detecting a malfunction of the vehicle's cooling system according to any one of claims 1 to 8. Motor vehicle comprising a system for detecting a malfunction of a vehicle according to claim 9.

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