Thermal energy diagnostic method for detecting operating anomalies of an electric circuit of a motor vehicle

Abstract

The invention relates to a diagnostic method for diagnosing an operating anomaly of a cooling system of a vehicle, in particular of an electric machine and of some associated electrical power elements, such as an inverter, of an embedded charger. The method comprises an estimation step for estimating a weighted temperature (424) determined on the basis of a barycenter calculation of the first and second weighted temperatures (422, 423), a determination of a threshold value (426) intended to calculate the lowest value between, on the one hand, an outside temperature (425) in the environment of the vehicle, and, on the other hand, the second temperature (423), a comparison step (427) for comparing the weighted temperature (424) with the threshold value (426), and an activation of a diagnostic step (200) for diagnosing an operating anomaly of the cooling system in the event of detection of the weighted temperature (424) below the threshold value (426).

Description

TECHNICAL FIELD

[0001] The present invention claims priority from French application No. 1912976, filed on November 20, 2019, the contents of which (words, drawings and claims) are incorporated herein by reference.

[0002] The present invention relates to a diagnostic method for diagnosing operating anomalies of a cooling system of an electric propulsion circuit in a vehicle, said diagnostic being set up for diagnosing a monitoring of the overall performance of the cooling system of the electric circuit, called low temperature circuit. The invention applies in particular to the supervision-control level of a hybrid or electric motor vehicle. BACKGROUND

[0003] One or several electric machines are used to ensure the propulsion of a motor vehicle in electric mode and are powered by a high voltage battery via some inverters. These electric circuits and said battery are strongly solicited, the Joule effect leading to an increase in temperature, thus requiring the installation of an adapted heat transfer (cooling fluid) cooling system.

[0004] The assembly is regulated on the basis of one or several computers, in particular grouped in an electronic control unit for the electronic control of the assembly, this electronic unit being able to communicate with other electronic control units embedded in the motor vehicle.

[0005] The thermal energy management system makes it possible to ensure the cooling of said one or several electric machines and of one or several electric elements associated with said electric machines (for implementing power electronics). The thermal energy state of these elements has a direct effect on the performance and on the availability of said electric circuit for propulsion, on the electric recovery and electric charging of the vehicle.

[0006] The aim of the invention is to evacuate the heat flow (thermal energy flux) generated by the different elements present on said electric low temperature circuit.

[0007] The motor hybrid or electric vehicle comprises at least one electric machine or electric engine for propelling said vehicle, said at least one electric machine being integrated into one or several electric circuits, said one or several electric circuits, in particular for the front or rear axle, comprising some electric elements, such as one or several inverters, a battery and a battery recharging device.

[0008] Currently, for the development of hybrid motor vehicles, new regulations require the implementation of an overall efficiency diagnosis of the low temperature cooling system described above.

[0009] As a result, the fundamental problem of the invention is to provide a combination in a motor vehicle of an assembly combined with an electrical circuit comprising at least one electric machine and a heat transfer fluid type cooling system to provide an operational diagnosis in order to meet regulatory requirements relating to the overall efficiency of said cooling system.

[0010] In particular, thermal energy management and methods for measuring and processing thermal information are essential. It is known from the prior art that patent document FR3055584A1 filed by the applicant describes an estimation method for estimating the ambient temperature in the environment of a member arranged under the hood of a generator. According to this method, the ambient temperature is estimated at least as a function of the temperature directly downstream of the cooling facade. The estimation of the ambient temperature in the environment of the member is also implemented as a function of the temperature of the engine and the rotational speed of the engine when the air flux speed is substantially zero. It is also known that patent document KR20180114411A describes an information collection unit to collect the temperature of an electronic component located inside a motor vehicle and the temperature of a second sensor located outside said motor vehicle in order to regulate the cooling louvers.

[0011] These solutions are based on the measurement of electronic sensors. However, these sensors can malfunction and provide false information which can compromise the thermal energy management of the electrical system and bring the system into a critical (severe) thermal energy situation.

[0012] It is therefore also necessary to install a high-performance monitoring system capable of predictively detecting overheating, failure or any anomaly in the electronic control elements, in particular sensors, in order to avoid critical failures during driving. SUMMARY

[0013] More precisely, the invention relates to a diagnostic method in a motor vehicle for diagnosing operational anomalies of a heat transfer fluid type cooling system for cooling an electrical circuit comprising at least one electric machine for propelling the vehicle and a battery designed to power the electric machine, the cooling system comprising a first cooling circuit for cooling the electric machine and a second cooling circuit for cooling the battery, the method comprising a measurement step for measuring first and second heat transfer fluid temperatures respectively in the first and second cooling circuits and a determination step for determining a lower temperature threshold, the method being characterized in that it additionally comprises:

[0014] - an estimation step for estimating a weighted temperature determined on the basis of the barycenter of the first and second weighted temperatures,

[0015] - determining a threshold intended to calculate the lowest value between, on the one hand, the outside temperature in the environment of the vehicle and, on the other hand, the second temperature,

[0016] - a comparison step for comparing said weighted temperature with said threshold value,

[0017] - in the event of detection of said weighted temperature being lower than said threshold value, a diagnostic step for diagnosing an operating anomaly of said cooling system is activated.

[0018] According to a variant, the activation of said anomaly diagnostic step is performed in the event of additional detection of activation of a circulation pump of heat transfer fluid of said second cooling circuit.

[0019] Some prerequisites for implementing said diagnosis are established, said prerequisites being at least some stable temperatures over a duration higher than some predetermined minimum time threshold, said temperatures being said first temperature, said second temperature and said external temperature.

[0020] According to a variant, said diagnostic step is performed if said detection remains activated for a duration with a predetermined duration delay.

[0021] According to the invention, a protection method for protecting an electric circuit cooled by a heat transfer fluid type cooling system in a motor vehicle is envisaged, characterised in that said protection method integrates a diagnostic method in accordance with any one of the above embodiments, and when performing an anomaly diagnosis of said cooling system, if said weighted temperature is lower than said threshold value, an increase in the flow rate of fluid in said cooling system is performed, accompanied by the emission of an alert destined for the driver of said vehicle and the suspension of any electric recharging of said circuit, such as energy recovery braking.

[0022] According to a variant of said protection method, when the increase in the flow rate of fluid or the suspension of any electric recharging of said circuit is not sufficient to bring said weighted temperature to above said threshold value, for a hybrid vehicle, a partial stop of at least one electric machine and a restart of a thermal energy engine for propelling said hybrid vehicle are performed, or, for an electric vehicle, an emergency stop alert destined for the driver of said motor vehicle can be emitted, for stopping said motor vehicle and / or a partial stop of at least one electric machine of said circuit can be performed (when several electric machines are present in said circuit).

[0023] There is also provided an assembly in a motor vehicle, said assembly combining an electric circuit and a heat transfer fluid cooling system for cooling said electric circuit, said assembly comprising at least one measuring or estimating means for measuring or estimating a first and a second fluid temperature, said electric circuit comprising at least one electric machine for propelling said vehicle and at least one electric element associated to said at least one electric machine to be cooled, said assembly comprising an electronic control unit in charge of the operation of said assembly and protected by the protection method according to any one of the preceding embodiments, wherein said electronic control unit comprises some reception means for receiving said measured first and second fluid temperatures, some estimation means for estimating said weighted temperature, some storage means for storing said threshold, some comparison means for comparing said weighted temperature to said threshold, some establishment means for establishing a diagnosis of an anomaly in said cooling system, and in that case, some increase means for increasing the flow of fluid in said cooling system, some emission means for emitting a visual or acoustic alert destined for said driver and some suspension means for suspending any electric recharging of said circuit, such as regenerative braking.

[0024] According to a variant of said assembly, the electronic control unit for controlling said assembly comprises some emission means for emitting a request towards a main electronic control unit of a hybrid motor vehicle, said request requesting at least partial stopping of said at least one electric machine with some restart means for restarting a thermal engine of said vehicle or some emergency request means for requesting at least partial stopping of said at least one electric machine for an electric motor vehicle.

[0025] According to a variant of said assembly, said at least one electric element is chosen from the following elements, taken separately or in combination: at least one inverter, at least one electric recharging device embedded in said motor vehicle, at least one high-voltage direct current to low-voltage direct current converter and at least one battery, said cooling system comprising at least one first cooling circuit for cooling said at least one electric element, said at least one electric element comprising a first pump and at least one heat sink, said at least one heat sink constituting or not constituting part of a motor-fan unit, said motor-fan unit some with a regulated louver damper, said electronic control unit being used to control actuating means of said louver damper in a maximum opening position when an increase means for increasing said fluid flow is activated, and comprising a second cooling circuit for cooling said battery, said second cooling circuit comprising a primary thermodynamic circuit of the type of a closed loop and a secondary circuit, said secondary circuit comprising a second pump and a heat exchanger, said heat exchanger being able to implement a calorie exchange between said primary circuit and said secondary circuit.

[0026] There is also provided an electric or hybrid motor vehicle, characterized in that it comprises an assembly combining an electric circuit and a heat transfer fluid type cooling system for cooling said electric circuit, said assembly complying with any one of the above embodiments.

[0027] The invention ensures a better protection of the components for protecting, for example, front and rear inverters, rear motor, embedded chargers and voltage converters, from overheating and also meets regulatory requirements related to embedded charger diagnostics. The detection implemented on a lower threshold calculated simultaneously on the basis of the temperature of the cooling circuit for cooling said battery and on the basis of the temperature of the cooling circuit for cooling said electric elements makes it possible to integrate thermal energy data and to detect anomalies that can affect the temperature sensors. The method implements a detection strategy and a preventive protection strategy that make it possible to detect inconsistencies. BRIEF DESCRIPTION OF DRAWINGS

[0028] Other objects, characteristics and advantages of the invention will become apparent on reading the following non-limiting description and on referring to the appended drawings, in which:

[0029] - Figure 1 The schematic diagram shows an assembly combining a propulsion electric circuit comprising at least one motor and a high-voltage battery and a heat transfer fluid type cooling system for cooling this circuit, to which the diagnostic method according to the invention can be applied.

[0030] - Figure 2a schematic view showing the architecture of an assembly combining a propulsion electric circuit comprising at least one electric machine and a high-voltage battery, and a heat transfer fluid type cooling system for cooling this circuit in a motor vehicle, in which the steps of an embodiment of a protection method for protecting said electric circuit according to the application are described in detail,

[0031] - Figure 3 a logic block diagram showing an embodiment in accordance with the application of a protection method for protecting an electric circuit comprising at least one propulsion electric machine and a high-voltage battery in a motor vehicle, and cooled by a heat transfer fluid type cooling system,

[0032] - Figure 4 eight graphs are shown, namely the graphs of the outside air temperature, of the heat transfer fluid temperature, of said weighted temperature and of said lower threshold, in various figure cases for implementing the method according to the application. DETAILED DESCRIPTION

[0033] Figure 1 a non-limiting example of an assembly combining a propulsion electric circuit comprising a drive electric machine 54 and a high-voltage battery 103, and provided with a cooling system, said cooling system being adapted to implement a diagnostic method for diagnosing operating anomalies of said cooling system and a protection method for protecting an electric circuit according to the application is shown. In this non-limiting example, the drive electric machine 54 is fitted on a rear axle of said vehicle, this rear axle being positioned in a rear region ZAR of said vehicle. Said cooling system comprises a first circuit 1001 called low temperature circuit, and a second circuit 1002 called ultra-low temperature circuit. Each of these circuits is arranged between this rear region ZAR and a front region ZAV of said vehicle.

[0034] The first circuit 1001 comprises in turn a radiator 58 positioned in the front region ZAV of said vehicle and possibly part of a motor-fan unit 7 equipped with a louver system 1, the louvers of which are regulated to take in more or less outside air outside said vehicle towards the low temperature radiator 58.

[0035] A fluid circulation pump 64 is able to circulate said cooling liquid from the radiator 58 towards an inverter 100 at the front region ZAV of said vehicle, then towards a current converter 101, then towards an inverter 102 at the rear region ZAR of said vehicle, then towards a traction electric machine 54 possibly located at the rear region ZAR of said vehicle, then back in the radiator 58.

[0036] The converter 101, either an embedded recharging device for recharging a high-voltage battery, which is commonly named by those skilled in the art with the acronym OBC for "On Board charger", or a high-voltage DC to low-voltage DC converter, which is used for the conversion between a high-voltage battery (for example a traction battery) and a low-voltage battery (for example a service battery), or a recharging device and a converter grouped together. The converter can also comprise a battery.

[0037] The first circuit 1001 additionally comprises a measuring means 60, for example a sensor or a temperature estimation member, for measuring the temperature of the heat transfer fluid 61. The sensor 60 can be positioned at the front zone ZAV or at the rear zone ZAR of the circuit 1001.

[0038] The separation between the front zone ZAV and the rear zone ZAR of the vehicle is schematically shown by the dashed line, while the radiator 58 is in the front zone ZAV of the vehicle.

[0039] The electronic control unit can control the electrical propulsion means, which comprise the power equipment(s), namely in this example the inverter 100 at the front of the vehicle, the current converter 101, the inverter 102 at the rear of the vehicle and the traction motor 54.

[0040] The electronic control unit, associated or not with the electronic units mentioned above, can control the cooling system of the propulsion electrical circuit by controlling the cooling control equipment(s), which are in this example the circulation pump 64, the motor-fan unit 7 and the louvred damper system 1. The electronic control unit or the plurality of electronic control units can for example be embedded in one of the power equipment to be cooled, in particular in the current converter 101. In a variant, the motor-fan unit 7 and the louvred damper system 1 can be controlled by a different electronic control unit, for example an engine control unit, which is used, if necessary, to control a thermal engine (in the case of a hybrid vehicle) and to determine the engine torque distribution between the one or several electric machines and the thermal engine.

[0041] The second circuit 1002 comprises the main thermal regulation circuit 1004 of the vehicle, of the type of a thermodynamic circuit, which typically comprises at least one compressor 105, a condenser 108 and an evaporator 107, and in which a heat transfer fluid circulates and is arranged for at least extracting and for providing caloric energy to the passenger compartment of the vehicle. To this end, the main circuit can be equipped with control means for controlling the circulation of the refrigerant fluid through the equipment to be thermally regulated, in particular through the passenger compartment heat exchanger, to distribute the circulation of the refrigerant fluid.

[0042] In addition, in the case of a rechargeable electric and hybrid vehicle equipped with a high-voltage traction battery, the vehicle is generally additionally equipped with a secondary cooling circuit 1003 in which a secondary fluid circulates, which is able to transfer thermal energy power between the battery 103 and the main circuit 1004 by means of a heat exchanger 106 (also called "chiller"). The heat exchanger 106 is an exchanger of the heat transfer fluid - secondary fluid type. The secondary circuit 1003 comprises a hydraulic pump 104 which circulates the secondary fluid (optionally glycol water) 113, through plate bodies or some tubes in contact with the thermal mass of the battery, in order to extract calories and then to evacuate the calories by evaporation of the refrigerant fluid in the heat exchanger 106.

[0043] The second circuit 1002 additionally comprises some measuring means 110, 111 for measuring the temperature of the heat transfer fluid 112, 113, for example some sensors or temperature estimation means. The sensors can be positioned at the front region ZAV, for example the sensor 110, or at the rear region ZAR of the circuit 1002, close to the battery 103, for example the sensor 111. The pump 104 and the compressor 105 can be controlled by the electronic control unit BMS ("Battery Management System") of the battery or by a different electronic control unit, for example the control unit for controlling the drive motor 54 (or, if necessary, for controlling the thermal engine).

[0044] With reference to Figures 1 to 3 The description of the diagnostic method and protection method according to the present application, with the propulsion electric circuit and its cooling system 1001, 1002 with at least the drive motor 54 and the high-voltage battery 103, forms a combination controlled by the electronic control unit 5. Such a cooling system is so-called low-temperature type compared to the cooling system of the thermal engine, whose heat transfer fluid temperature is higher and so-called high-temperature type.

[0045] The diagnostic method for diagnosing operating anomalies is intended to detect overheat situations of the electric circuit 100 to 103, as well as anomalous situations that can be caused by a malfunction of the temperature measuring means. The purpose of the diagnostic method is to be dedicated to detecting this latter case.

[0046] More precisely, the diagnostic method is designed so as to determine a lower threshold 426, and preferably an upper threshold 412. This upper threshold is implemented by the control unit for detecting an overheat of the cooling system.

[0047] The diagnostic case of diagnosing an overheating will not be described in detail in the present description, but a brief introduction of the concept is still provided to globally understand the diagnostic method that can be implemented by the assembly. The diagnostic method for diagnosing an overheating is intended to compare, at step 413, the measured temperature 410 of the heat transfer fluid 61 of the first cooling circuit 1001 with an upper threshold 412 when the measured temperature 410 is higher than said upper threshold, the block 413 activates a high state of the Boolean signal (VRAI) and thus performs the diagnostic step 200 for diagnosing whether the cooling system is in an overheating. Preferably, the threshold 412 depends on the configurable threshold 411 and on the weighted temperatures 406 to 409 of the electrical elements, such as the driving motor 54 and the electrical elements 100 to 102. However, other determining variants for determining the threshold 412 can be envisaged without departing from the scope of the application. The diagnostic step 200 is performed if the detection remains active (valid) during a duration with a delay 429 of a predetermined duration, such as 120 seconds.

[0048] More precisely, the application is intended to detect a case of operating anomaly of the cooling system likely to be caused by a failure of the measuring means 60 for measuring the temperature of the heat transfer fluid 61 of the circuit 1001.

[0049] To this end, the diagnostic method comprises a measuring step 421 for measuring a first temperature 422 and a second temperature 423 of the heat transfer fluid in the first 1001 and second 1002 cooling circuits respectively, an estimating step for estimating a weighted temperature 424 determined on the basis of a barycenter calculation of the first and second weighted temperatures 422, 423. First and second coefficients are respectively assigned to the temperatures 422, 423. The coefficients are configured so as to calculate, for example, a weighted temperature 424 of 20°C for a temperature 422 of 10°C and for a temperature 423 of 60°C. However, other coefficient values can be envisaged.

[0050] The temperature 422 is exactly the same as the temperature 410 and is read by the same sensor.

[0051] The second temperature 423 can be the temperature of the heat transfer fluid 113 of the cooling circuit 1003, the temperature of the heat transfer fluid 112 of the circuit 1004, also or further a composite temperature of the heat transfer fluid 113 and of the fluid 112. The weighted temperature 424 is intended to take into account the temperature 423 of the circuit 1002 (as this temperature is more stable with respect to the temperature 422) so as to integrate and to make reliable the temperature data used for implementing the diagnostic of the cooling system for operating the diagnostic. In particular, the reliability is improved for cold weather with negative temperatures (such as -15°C) and for the condition of leaving the garage when the ambient temperature of the vehicle is about 20°C.

[0052] The method then comprises a determination step for determining a threshold 426, which aims to calculate the minimum between, on the one hand, the outside temperature 425 in the outside environment of the vehicle, and, on the other hand, the second temperature 423 of the second circuit 1002, then a comparison step 427 for comparing the weighted temperature 424 with the threshold 426.

[0053] In the case where the weighted temperature 424 is detected below the threshold 426, the plate 427 activates the high state of the Boolean signal (VRAI). The method thus activates a diagnostic step 200 for diagnosing an operating anomaly of the cooling system. The diagnostic 200 is activated if the output signal of the plate 427 or (reference 430) and, if necessary, the output signal of the plate 413, are both activated, that is to say in the Boolean state VRAI and while the activation conditions for activating the monitoring of the diagnostic remain present (plate 209).

[0054] In a preferred variant, the method additionally governs the activation state of the hydraulic pump 104 of the second cooling circuit 1002 to ensure a regular circulation state of the heat transfer fluid, that is to say regulated by the ratio of the non-zero control signal. As a result, the method aims to perform the activation of the activation anomaly diagnostic step 200 in the case where the activation 428 of the circulation pump of the heat transfer fluid of the second cooling circuit 1002 is additionally detected (plate in the high state or VRAI). This supplementary governing step aims to guarantee that a uniform temperature is measured in the circuit 1002.

[0055] The plate 431 added in this preferred variant thus activates the high state of the Boolean signal (VRAI) if, simultaneously, the two plates 427 and 428 are in the high state. In the opposite case(s), the plate 431 regulates the low state (FAUX) for disabling the diagnostic.

[0056] The operating anomaly is the observation that the temperature of the heat transfer fluid 61 on the cooling circuit 1001 is implemented below the compounded minimum of the outside air temperature 425 and the temperature of the cooling fluid of the battery. This case is impossible and can only be the result of a (malfunctioning) water temperature sensor 60.

[0057] In the case where the diagnostic 200 is detected, some precautionary measures are applied and aim to regulate some degraded modes in order to attempt to cool the circuit in the case of possible overheating, since in this case the control unit is not able to know the actual temperature of the heat transfer fluid.

[0058] As Figure 3As shown, preferably, the diagnostic step 200 is performed exactly as the overheating diagnosis, if the detection remains active during the delay 429 with a predetermined duration.

[0059] Moreover, some prerequisites 400 to 402 for implementing the diagnosis 200 are preferably established.

[0060] The first condition 400 concerns the activation of the pump of the cryogenic circuit, the second condition 401 concerns the operability of the temperature sensor, and the third condition 402 concerns the stability of the external ambient temperature 425, and of the temperatures 422, 423 of the heat transfer fluid of the cooling system.

[0061] The first condition 400 serves to control the regular circulation of the fluid 61 in the circuit 1001, or aims to confirm the presence of an electrical fault at the location of the pump 64, for example the detection of an open circuit, a short circuit to the positive terminal, or a short circuit to the ground terminal.

[0062] The second condition 401 is the reading of the temperature of the fluid 422 performed by the temperature sensor 60 controlled to be operational, or aims to confirm the presence of an electrical fault at the location of the sensor 60, for example the detection of an open circuit, a short circuit to the positive terminal, or a short circuit to the ground terminal.

[0063] The third condition 402 serves to control the stability of the weighted temperature over a duration (delay 403) higher than some predetermined minimum time threshold, the temperature being the first temperature 422 of the fluid 61 in the circuit 1001, the second temperature 423 of the fluid in the circuit 1002 and the external temperature 425.

[0064] After the delay 429 with a predetermined duration, and preferably when the activation conditions (400 to 402) for activating the monitoring 209 of the diagnosis are still present after the delay 403, the comparison step 427, and / or 413 if necessary, or the comparison steps 427 and 431 of the diagnostic method can be performed.

[0065] It is indeed necessary to have the external air temperature and the temperatures of the heat transfer fluid on the cryogenic circuit 1001 and the ultra-cryogenic circuit 1002 sufficiently stable during the activation 402 of the diagnosis in order to avoid any false detections. False detections can for example occur when passing in a tunnel or leaving a garage, but this is not limiting.

[0066] For example, in cold weather with an outside air temperature of -5°C, a motor vehicle parked outside is started and has an outside air temperature equal to the heat transfer fluid temperature 422, 423 and also equal to the hottest temperature of the elements of the electrical propulsion circuit, all equal to -5°C.

[0067] When the motor vehicle is running and enters a tunnel or an underground parking lot, the outside air temperature can instantaneously pass from -5°C to 10°C / 15°C, while the temperature of the heat transfer fluid and of the hottest element of the circuit, considering the material inertia of the elements, increases only slowly.

[0068] In particular, if the distance travelled is small, there is a risk that the outside air temperature is currently temporarily higher than the fluid temperature, which in turn is higher than the temperature of the hottest element of the propulsion electrical circuit. This would give a false diagnosis and should be avoided.

[0069] Therefore, the diagnosis is only necessary to be implemented when the outside air temperature is stable 402 to achieve a reliable anomaly detection at the location of the cooling system for cooling the propulsion electrical circuit.

[0070] When the prerequisites 400 to 402 are detected and when the anomaly 200 is diagnosed to be crossed by the lower threshold or by the upper threshold, with the pump 104 activated in rotational rotation, the activation of the protection measure or of the degraded operating mode is implemented, in Figure 3 the figure is 404.

[0071] The present invention also relates to a protection method for protecting an electrical circuit cooled by a heat transfer fluid type cooling system in a motor vehicle. The protection method integrates the diagnostic method according to any one of the above embodiments, that is to say, the implementation of the activation 209 of the monitoring 202 of the temperature of the cooling system to detect an operating anomaly of the temperature sensor of the cooling circuit 1001.

[0072] With reference to Figure 3 To implement the diagnosis, a comparison step 427 for comparing the estimated weighted temperature 424 with a lower threshold 426 is implemented, and in the event of detection of a weighted temperature 424 lower than the lower threshold 426 and with the pump 104 activated in rotational rotation, a diagnostic activation step 200 for activating the diagnosis of an operating anomaly of the cooling system is implemented.

[0073] When the abnormality diagnosis of the cooling system is activated, certain protective measures are performed to regulate some degraded modes in order to protect the electrical assemblies of the vehicle and terminate the abnormal operation, which in the case of the invention is the temperature inconsistency of the heat transfer fluid 61.

[0074] Among these measures, the electronic control unit 5 at least regulates and implements an increase 201 in the flow rate of fluid 61 in the cooling system, accompanied by the activation of an alarm 208 directed at the driver of the vehicle. This increase 201 can be adjusted and has different levels, and is preferably regulated to the maximum speed.

[0075] Simultaneously, it is possible to initiate the sending of an alarm 203 to the electronic engine control unit 6, which includes a computer 204 and several transmitting components for sending requests for auxiliary protection measures to the propulsion electrical circuit and to components 205 that cooperate with the electrical circuit.

[0076] The auxiliary protection measure is to suspend any electrical recharging of the circuit, such as heat-releasing recharging, or energy recovery braking 207, such as by sending a message to the track electronic corrector indicating that the regenerative braking has been suspended.

[0077] These measures 201 and 207 are emergency measures taken immediately upon detection of operational anomalies or overheating, but may prove insufficient. In such cases, when increasing the fluid flow rate 201 or pausing any electrical recharging of the circuit 207 is insufficient to bring the read temperature of the fluid between the lower threshold 426 and the upper threshold 413, at least a partial stop 206 of the at least one motor 54 and the restart of the thermal engine used to propel the hybrid vehicle may be performed for the hybrid vehicle.

[0078] For electric vehicles, an emergency alarm 208 can be emitted with the driver of the vehicle as the destination, which is used to stop the vehicle and / or can perform at least partial to full (when multiple motors 54 are present in the circuit) stop 206 on at least one motor 54 of the circuit.

[0079] In the case of an electric motor-driven vehicle, the motor 54 used for the propulsion electrical circuit may only include motor 54, or in the case where the circuit includes multiple motors 54, all motors in the propulsion electrical circuit may not be able to be stopped.

[0080] It is possible to continue propulsion of the hybrid or electric vehicle by adjusting one or more motors 54, thereby causing these motors to release less heat.

[0081] According to the method of protection Figure 2 described above, when the conditions 400 to 402 relating to the prerequisites for implementing the diagnosis are detected, i.e. the absence of electrical faults on the pump of the circuit 1001, the operability of the temperature sensor 60, and the stability of the outside ambient temperature 425, and of the heat transfer fluid temperature 422, 423 of the cooling system, the monitoring 209 is activated. Figure 3

[0082] With reference to all the figures, the present application also relates to an assembly in a motor vehicle, said assembly combining an electrical circuit and a cooling fluid cooling system of this electrical circuit, said assembly comprising at least one measuring member 60, 110, 111 for measuring or estimating the temperature of said fluid, and advantageously a temperature sensor.

[0083] Said electrical circuit comprises at least one propulsion electric machine 54 for propelling said vehicle and at least one electrical element 100 to 102 associated with said at least one electric machine 54 to be cooled, the list of potential electrical elements having been given above.

[0084] Said assembly comprises an electronic control unit 5 responsible for the operation of the assembly and protected by the protection method described above.

[0085] To this end, the electronic control unit 5 comprises some reception means for receiving the temperature of the measured fluid, advantageously from the fluid temperature sensor 60, 110, 111, and some storage means for storing the lower 427 and upper 413 threshold values.

[0086] The electronic control unit 5 also comprises some storage means for storing the weighting coefficients assigned to each temperature 422, 423, some estimation means for estimating the weighted temperature 424 based on the (some) weighting coefficients of the barycentric calculation, some comparison means for comparing the weighted temperature 424 with the lower threshold 427, and some establishing means for establishing that the cooling system is diagnosed as being abnormal. In this case, in the presence of an uncertainty relating to the temperature values of the heat transfer fluid in said low temperature circuit, the electronic control unit 5 activates some increase means 201 for increasing the flow of fluid in said cooling system, some emission means for emitting a visual or acoustic alert 208 destined for the driver, and some suspension means for suspending any electrical recharging of the circuit, such as energy recovery braking 207, as (some) basic protection measures.

[0087] ​The electronic control unit 5 of the assembly comprises some transmitting means for transmitting a request towards a main electronic control unit 6, also called engine control unit, requesting the implementation of at least partial stopping 206 of the at least one electric machine 54 of the hybrid motor vehicle with some restarting means or some emergency request means for restarting the thermal engine of the vehicle or for urgently requesting at least partial stopping 206 of the at least one electric machine 54 (for electric motor vehicles) towards the main electronic control unit 6 (also called engine control unit).

[0088] The electronic control unit 5 for controlling the assembly can control some actuating means for actuating the ventilation flap 1 in the maximum open position when the increasing means 201 for increasing the fluid flow are activated.

[0089] The application is also more intended for an electric motor vehicle than for a hybrid motor vehicle.

[0090] The electronic control units 5 and 6 are equipped with integrated circuit type computers and (some) electronic memories configured for jointly performing the diagnostic and protection methods according to the application. But this is not mandatory. Indeed, these computers can be configured in the form of a single centralized control unit. Thus, the control units according to the application can be implemented in the form of software (or information also or "software (software)") modules, or electronic circuits (or "Hardware (hardware)"), or a combination of electronic circuits and software modules.

[0091] Figure 4 With reference to Figure 1 , different curves obtained when implementing the method according to the application are shown.

[0092] In the first graph GR1, the evolution of the validity domain involving the outside air temperature 425, the cooling circuit fluid temperature 422 of the so-called low temperature circuit of the electric machine, and the fluid temperature 423 of the cooling circuit of the battery is shown, these curves temporarily coinciding. The validity domain is calculated based on the evolution of the outside air temperature 425 on the graph GR3 and based on the evolution of the fluid temperature 422 of the low temperature circuit and the fluid of the cooling circuit 423 of the battery on the graph GR4. The validity domain is able to identify the zones in which some sudden temperature variations occur, in order to avoid any false detections at the diagnostic location. The validity domain is indicated by some Boolean signals which have a 1 (VRAI) value when the temperatures are stable and a 0 (FAUX) value in the case of instability, i.e. rapid variations of the temperature values.

[0093] On the graph GR2, no electrical fault is read on the water pump 64 of the low temperature cooling circuit and on the temperature sensor of the low temperature fluid. The double arrow shows the activation of the monitoring when the prerequisites (stability of the fluid temperature and outside temperature, activation of the pump, regular functioning of the sensor) are detected. All the conditions are satisfied to (be able to) ensure correct detection of operating anomalies.

[0094] On the graph GR4, the fluid temperature 422 (short dashed line) and the fluid temperature 423 (solid line) are shown. The weighted temperature 424 is shown in long dashed line and is calculated according to the weighting coefficients assigned to each fluid temperature 422, 423. For example, at t = 700 s, the temperature 422 is equal to 10°C, the temperature 423 is equal to 60°C and the weighted temperature 424 is equal to 20°C.

[0095] On the graph GR5, the calculation of the lower threshold 426 is defined, which is equal to the minimum between the outside air temperature 425 and the fluid temperature 423 of the cooling circuit. As can be seen on the graph, at t = 700 s, the water temperature 423 is equal to 60°C and the outside air temperature is 40°C. The lower threshold 426 is therefore equal to 40°C.

[0096] On the graph GR6, the method detects (an) anomaly at the moment when the fluid temperature 424 becomes lower than the lower threshold 426 and the pump of the cooling circuit of the battery is activated (the signal 428 is in the VRAI state), as can be seen on the graph GR7. The detection moments DT1, DT2 are represented on GR6 by some double arrows and some arrows show the relationship of these moments with the activation of the graph GR8.

[0097] On the graph GR8, for example a delay of 120 seconds, the fault is then diagnosed at the end of the delay duration, triggered from the detection instants DT1, DT2 and if the fault is still active after this delay. The signal DG switches to the state VRAI(1) (in this example only for DT2 (diagnosis (signal) activated) and indicates that a weighted temperature 424 below the threshold 426 is detected with a confirmed condition 428 (GR7) and the prerequisites 400 to 402 (GR2) correctly fulfilled. The one or some protection measures or or degraded mode mentioned above are triggered when the diagnosis signal DG is activated.

[0098] The diagnosis signal DG is disabled from the instant at which it is observed that the weighted temperature 424 becomes higher than the lower threshold while remaining lower than the upper threshold, or in the case where it is detected that the water pump of the cooling circuit of the battery is not activated, or in the case where the activation prerequisites are no longer fully satisfied, that is to say the temperature of the heat transfer fluid or of the outside air becomes unstable, or in the case where it is detected that a fault occurs on the water pump or on the water temperature sensor of the low temperature circuit.

Claims

1. A diagnostic method in a motor vehicle for diagnosing operational abnormalities of a heat transfer fluid cooling system for cooling an electrical circuit, the electrical circuit including at least one propulsion motor (54) for propelling the vehicle and a battery (103) designed to power the motor (54), the cooling system including a first cooling circuit (1001) for cooling the motor (54) and a second cooling circuit (1002) for cooling the battery (103), the method including a measurement step (421) for measuring first and second temperatures (422, 423) respectively in the first and second cooling circuits (1001, 1002) and a determination step for determining a lower temperature threshold (426), the method being characterized by further including: - An estimation step for estimating the weighted temperature (424), which is determined based on the centroids of the measured first and second temperatures (422, 423). - Determine a threshold (426) that is designed to calculate the minimum value between, on the one hand, the external temperature (425) in the environment of the vehicle, and on the other hand, the second temperature (423). - A comparison step (427) for comparing the weighted temperature (424) with the threshold (426), - If the weighted temperature (424) is detected to be lower than the threshold (426), a diagnostic step (200) for diagnosing an operational abnormality of the cooling system is activated.

2. The diagnostic method according to claim 1, characterized in that, The activation of the anomaly diagnosis step is performed if the activation of the circulation pump (428) of the heat transfer fluid in the second cooling circuit (1002) is detected in addition.

3. The diagnostic method according to claim 1 or claim 2, characterized in that, A prerequisite (209) for performing the diagnosis is established, the prerequisite being a stable temperature (402) for at least a duration greater than a predetermined minimum time threshold, the stable temperature being the first temperature (422), the second temperature (423), and the external temperature (425).

4. The diagnostic method according to claim 1 or 2, characterized in that, If the detection remains active during a duration of a delay (429) with a predetermined duration, the diagnostic step (200) is performed.

5. A protection method for protecting an electrical circuit cooled by a heat transfer fluid cooling system in a motor vehicle, characterized in that, The protection method includes a diagnostic method conforming to any one of claims 1 to 4, and when performing an abnormality diagnosis of the cooling system, if the weighted temperature (424) is below the threshold (426), an increase (201) in the flow rate of fluid in the cooling system is performed, accompanied by the emission of an alarm (208) directed to the driver of the vehicle and suspension of any electrical recharging of the circuit.

6. The protection method according to claim 5, characterized in that, When increasing the fluid flow rate (201) and suspending any electrical recharging of the circuit (207) is insufficient to bring the weighted temperature (424) above the threshold (426), for hybrid vehicles, at least a partial stop (206) of the at least one motor (54) and restart of the thermal engine for propelling the hybrid vehicle are executed, or for electric vehicles, an emergency stop alarm (208) is launched for the motor vehicle and directed to the driver of the motor vehicle is executed and / or at least a partial stop (206) of at least one motor (54) of the circuit is executed when multiple motors (54) are present in the circuit.

7. The protection method according to claim 5, characterized in that, The electrical recharging of the circuit is an energy recovery stop (207).

8. An assembly in a motor vehicle, the assembly comprising an electrical circuit and a heat transfer fluid cooling system for cooling the electrical circuit, the assembly including at least one measuring or estimating member for measuring or estimating first and second fluid temperatures (422, 423), the electrical circuit including at least one propulsion motor (54) for propelling the vehicle and at least one electrical element (100 to 103) associated with the at least one motor (54) to be cooled, the assembly including an electronic control unit (5) responsible for the operation of the assembly and protected by a protection method conforming to claim 5 or claim 6, characterized in that, The electronic control unit (5) includes a receiving unit for receiving measured first and second fluid temperatures (422, 423), an estimation unit for estimating the weighted temperature (424), a storage unit for storing the threshold (426), a comparison unit for comparing the weighted temperature with the threshold (426), an establishment unit for establishing a diagnosis that the cooling system is malfunctioning, and in this case, an increase unit (201) for increasing the fluid flow rate in the cooling system, a transmitter unit for emitting a visual or audible alarm (208) directed at the driver, and a pause unit for suspending any electrical recharging of the circuit.

9. The assembly according to claim 8, characterized in that, The electronic control unit (5) for controlling the assembly includes a transmitting component for transmitting a request toward the main electronic control unit (6) of the hybrid electric vehicle, the request being used to request at least a partial stop (206) of the at least one motor (54) by means of a restart component or an emergency request component, the restart component being used to restart the thermal engine of the vehicle, and the emergency request component being used to request at least a partial stop (206) of the at least one motor (54) for electric motor vehicles.

10. The assembly according to claim 8 or claim 9, characterized in that, The at least one electrical component (100 to 103) is selected from the following components, which may be used individually or in combination: at least one inverter (100, 102), at least one electric recharging device embedded in the motor vehicle, at least one high-voltage DC to low-voltage DC converter (101), and at least one battery (103). The cooling system includes at least one first cooling circuit (1001) for cooling the at least one electrical component (100 to 102), the at least one electrical component including a first pump (64) and at least one radiator (58), the at least one radiator forming part of a motor-fan unit (7), the motor-fan unit having a... The electronic control unit (5) controls the actuation component of the louver damper (1) to be in the maximum opening position when the increasing component for increasing (201) the fluid flow is activated, and includes a second cooling circuit (1002) for cooling the battery (103), the second cooling circuit including a main thermal energy regulation circuit (1004) and a secondary circuit (1003) of the thermodynamic circulation loop type, the secondary circuit including a second pump (104) and a heat exchanger (106) capable of performing calorie energy exchange between the main thermal energy regulation circuit (1004) and the secondary circuit (1003).

11. The assembly according to claim 8, characterized in that, The electrical recharging of the circuit is energy recovery braking (207).

12. The assembly according to claim 10, characterized in that, The at least one radiator is not part of the motor-fan unit (7), which has an adjustable louvered damper (1).

13. An electric or hybrid electric vehicle, characterized in that, The motor vehicle includes an assembly comprising an electrical circuit and a heat transfer fluid cooling system for cooling the electrical circuit, the assembly conforming to any one of claims 8 to 12.

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