FR3097172A1 - THERMAL MANAGEMENT PROCESS OF A BATTERY ALLOWING TO ADAPT THE THERMAL REGULATION TRIP THRESHOLD ACCORDING TO THE TRANSFERRED ELECTRICAL POWER - Google Patents

Abstract

The present invention relates to a method of thermal management of an electric battery (101) of a battery system (300) comprising an interface for transferring electrical energy (500) between the battery (101) and a terminal. recharging (600) external to the system (300) and thermal regulation means (100, 200) of the battery (101), the method comprising a step of controlling a thermal regulation operation when the temperature of the battery exceeds a predetermined trigger threshold. According to the invention, the method further comprises the following successive steps: the detection of an energy transfer operation between the battery (101) and the terminal (600), the determination of a value representative of the electric power transferred (PE) during said transfer operation, the configuration of the trigger threshold as a function of said value. The invention finds an advantageous application for rapid recharging of motor vehicles or for fixed stations. Figure 1

Description

METHOD FOR THERMAL MANAGEMENT OF A BATTERY FOR ADAPTING THE TRIP THRESHOLD OF THE THERMAL REGULATION AS A FUNCTION OF THE TRANSFERRED ELECTRICAL POWER

The field of the invention relates to a process for thermal management of a rechargeable electrochemical battery, in particular for electric traction vehicles equipped with a charging interface.

In the automotive industry, the latest technological advances have enabled manufacturers to offer vehicles fitted with high-capacity batteries (up to 120kW), thus offering a range of up to 500km. To make these vehicles usable on the motorway, it was necessary to deploy high-power HPC charging stations, for "High Power Charge" according to the English acronym. The regulations for the electrical infrastructure of charging stations currently provide for powers of up to 350kW in order to fully recharge a high-capacity battery in about twenty or thirty minutes.

As known to those skilled in the art, maintaining battery temperature within an optimal operating temperature range is necessary to reduce aging and increase electrical efficiency. By way of example, the applicant has already filed patent application FR3057998A1 describing an optimized temperature control process taking into account the gradient of the electrical power delivered by the battery to the electrical components of the vehicle to determine the commands of the system. thermal regulation.

When a vehicle is connected to a charging station, conventional battery thermal management strategies trigger cooling when the battery temperature exceeds a predetermined temperature threshold. This threshold is fixed regardless of the electrical charging power.

However, during a fast charge of 50kW or more, the thermal management of the batteries is confronted with much higher thermal powers than that of a conventional charge which must be dissipated in a reduced period of time. The difference in charging power can cause heating that can temporarily bring the battery into an operating zone accelerating aging, due to the thermal dynamics and the inertia of the thermal mass of the battery.

It is therefore necessary to propose a thermal management process for the battery when charging on an external terminal to maintain the electrical cells within operating ranges guaranteeing the safety of the vehicle and avoiding accelerated aging of the cells,

More specifically, the invention relates to a method for thermal management of an electric battery of a battery system comprising an interface for transferring electrical energy between the battery and a charging station external to the system and thermal regulation means of the battery, the method comprising a step of controlling a thermal regulation operation when the temperature of the battery crosses a predetermined trigger threshold. According to the invention, the method further comprises the following successive steps:

- The detection of an energy transfer operation between the battery and the terminal,

- The determination of a value representative of the electrical power transferred during said transfer operation,

- The configuration of the trigger threshold according to said value.

According to a variant, the configuration step consists in determining the trigger threshold from a predetermined map, recorded in the memory of a control unit of the thermal regulation means, the map being capable of delivering several threshold values in function at least of the value representative of said electrical power transferred.

According to a variant, the configuration of the triggering threshold is also a function of the instantaneous state of charge of the battery and of the temperature of the air outside the system.

According to a variant, the trigger threshold is configured at a first threshold value during the transfer operation, then in the event of detection of the end of the transfer operation, the trigger threshold is configured at a second value of threshold lower than the first value according to a predetermined temperature offset.

According to a variant, the value is the electrical power transferred between the charging station and the transfer interface of the system.

According to a variant, the value is a datum of a flow of digital information communication between the charging terminal and the transfer interface representative of the electrical power available by the terminal.

According to a variant, the data identifies a type of electrical connector connecting the transfer interface to the terminal, or a predetermined charging mode representative of a predetermined electrical power.

According to a variant, the transfer operation is an operation of charging electrical energy from the battery or discharging electrical energy from the battery through the charging terminal.

Consideration is given according to the invention to a control unit of a system comprising an electric battery, an interface for transferring electric energy between the battery and a charging terminal external to the system and means for thermal regulation of the battery. According to the invention, the control unit is configured to implement the method according to any one of the preceding embodiments.

The invention further relates to a motor vehicle comprising such a control unit.

The invention has the advantage of adapting and anticipating the cooling to be provided to the battery according to the charging mode and the electrical power which is transferred during this operation. The thermal management process avoids degraded battery operation by anticipating significant thermal dynamics during HPC charging.

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

represents an assembly comprising a rechargeable battery system, a battery charging interface with an external charging terminal and a battery thermal regulation system allowing the implementation of the thermal management method.

represents an algorithm of an embodiment of the thermal management method according to the invention.

represents a curve representative of the evolution of the temperature of the battery and several values of temperature thresholds determined in accordance with the method according to the invention as a function of the electrical power transferred.

FIG. 1 represents a battery system 300 allowing the implementation of the thermal management method of a battery 101 in accordance with the invention. The invention finds an application advantageously for a rechargeable electric/electric hybrid vehicle equipped with the system 300 and more precisely during a so-called HPC recharge in order to adapt the control of the thermal regulation of the battery according to the thermal dynamics and the inertia of the thermal mass of the battery. The method will be described below for an electromobility application for a motor vehicle comprising the battery system. Nevertheless, the thermal management process also applies to stationary applications where the battery is thermally regulated. In addition, an application of the method is envisaged for energy transfers from the battery both in charge from the electrical network, and in discharge to the electrical network through the charging interface, in particular for so-called "Smart Grid" applications. for smart grid.

More specifically, the battery system 300 comprises a rechargeable electrochemical battery 101, a battery charging interface 500 intended to transfer electrical energy with a charging terminal 600 external to the vehicle, a thermal regulation system for the battery 100 , 200 and a control unit 400 of the system 300 capable of controlling the thermal regulation system 100, 200, also called supervisor, ECU or VCU for “Electric Control Unit” and “Vehicle Control Unit” in English.

Conventionally, the traction battery 101 is made up of several electrical cells for storing electrical energy and is controlled by a specific control module BMS 102 (“Battery Management System”) whose function is to control the recharging cycles. and discharge during the various life situations encountered by the vehicle, whether driving, stationary, or even when the vehicle is connected to an external charging station 600 through the charging interface 500.

The function of the BMS 102 control module is in particular to control the charge/discharge current. The current can be determined as a function of the instantaneous temperature of the battery, of the current deliverable by the charging terminal 600, of the state of charge SOC (“State of Charge” in English), of the aging criterion of the battery or many more planned charging strategies according to the planned route of the vehicle.

In the context of HPC charging, charging current control strategies most often aim to obtain a minimum charging time and to benefit from the maximum charging current accepted by the battery at each instant of the electrical charge. The determination of the value of the optimal current is not the object of the invention here and may be dependent on various charging strategies specific to each manufacturer.

The invention described in the present description relates more specifically to the thermal management of the battery which is an essential related functionality of the load to benefit from the optimal charging current, and addresses in particular the control of the thermal regulation system of the vehicle. The thermal management method of the invention applies in cooperation with any type of charging current control strategy, and in particular targets HPC charging strategies where the value of the charging current is equal to or greater than 1 C- rate, i.e. a constant charging current allowing the full capacity of the battery to be charged in one hour or less, 30 minutes for a constant current of a value of 2 C-rate.

In a manner known per se, the BMS control device 102 of the battery 101 can act as a current regulator so as to prevent the electric cells from exceeding critical operating limits defined according to the electro-chemistry constituting the battery, for example a minimum temperature limit equal to approximately 15°C and a maximum temperature limit equal to approximately 60°C. These limitations are likely to increase the charging time in the event of temperature saturation, hence the importance of thermal management and anticipation of the electrical power transferred between the battery 101 and the charging station 600.

In addition, the BMS control device 102 is capable of controlling a thermal regulation mode by cooperating with the thermal regulation system of the vehicle so as to transfer thermal power to the battery for heating and cooling.

The BMS 102 control device comprises means for measuring the activity parameters of the battery and is capable of providing information concerning its parameters which can be used by the VCU 400 control unit to trigger a thermal regulation mode. Among the parameters that can be used, mention may be made of the electrical power transferred in charge and discharge to and from the battery 101 through the charging interface 500, the state of charge level SOC (“State of Charge”), the instantaneous temperature, the maximum acceptable temperature, a setpoint temperature, the voltage at the battery terminals, the charge/discharge current, an accepted charge current depending on the state of charge level and the instantaneous temperature, the internal resistance or else the state of health parameters, the digital data of the COM flow of information communication between the terminal 600 and the interface 500, the current and the voltage available by the charging terminal 600, the type of electrical connection of the charging station, the charging mode defined by the electrical charging power (between 3kW and 350kW) or the discharge mode through charging station 600 to the external electrical network (domestic for example).

The charging interface 500 (or electrical energy transfer interface) is able to allow unidirectional or bidirectional transfer of electrical energy between the external terminal 600 and the interface 500. The interface 500 comprises an electrical outlet, ( for example type 1, type 2, type 4, combo, CCS ("Combined Charging System" in English, CHAdeMO) and electronic power means allowing a transfer of electrical energy in direct or alternating single-phase or three-phase type voltage and charging/discharging means according to powers which can vary from a few kW to several hundred kW.

In addition, the charging interface 500 is capable of detecting from the flow of electrical power transferred whether the electrical connection with the external terminal is of alternating or direct voltage, as well as the level of electrical voltage used for the charge, or else the intended charging mode (mode 1, 2, 3 or 4 defining an electrical transfer power) from data of a digital information communication flow COM between the terminal and the charging interface in a manner to determine the trigger temperature threshold.

More specifically, the charging mode (1, 2, 3 or 4) is a predetermined mode defining the communication protocol between the interface and the terminal. This protocol includes data making it possible to determine the type of voltage used and the electrical power limitations or any charge control data ensuring the safety of the charging and making it possible to detect the electrical power transferred. According to a variant of the thermal management method, the control module 401 associates a predetermined temperature threshold with each predetermined charging mode. The thresholds vary in decrease when the transfer power increases.

Furthermore, a command of the thermal regulation operation consists in activating/deactivating the cooling/heating action of the battery 101 when the instantaneous temperature of the battery crosses the trigger threshold. For example, a thermal throttling strategy in cooling seeks to keep the battery temperature below the maximum limit. To this end, the control unit activates the cooling action when the instantaneous temperature of the battery exceeds a trigger threshold and deactivates the cooling action when the instantaneous temperature falls below the trigger threshold. The reverse control process is provided for heating, for a trigger threshold allowing the battery temperature to be maintained above a minimum limit. In heating, the control unit activates the heating action when the instantaneous temperature is lower than a trigger threshold in heating and deactivates the heating when the instantaneous temperature is higher than the trigger threshold.

In accordance with the invention, the trigger threshold is configured as a function of at least the electric power transferred between the battery 101 and the charging terminal 600 through the charging interface 500. To this end, the control unit 400 comprises a control module 401 whose function is to configure the temperature triggering threshold value of the thermal regulation operation of the battery. The control module 401 adapts the value of the triggering threshold according to the electrical power transferred so as to adapt the cooling/heating action according to the dynamics and thermal inertia of the battery. As a variant, the threshold is configured as a function, in addition, of the instantaneous state of charge of the battery and of the temperature outside the vehicle.

Furthermore, the vehicle's thermal regulation system comprises a main loop 200 which consists of a main circuit 210 in which a refrigerant fluid circulates comprising at least one compressor 201, one condenser 205, one expansion valve and one evaporator. In the case of an electric vehicle and rechargeable hybrid vehicle, very often the thermal regulation system also comprises one or more secondary loops (as represented in FIG. 1), each comprising a heat exchanger, dedicated to the specific thermal needs of the battery. , the passenger compartment or even a traction module of the vehicle. Nevertheless, the thermal management method according to the invention would also apply to other variants of regulation systems. The scope of the method according to the invention is in no way limited by the physical architecture of the thermal regulation system. In a simplified architecture, the battery could be thermally regulated by a radiator system associated with a fan without departing from the scope of the application of the thermal management method.

According to the architecture of FIG. 1, as is generally the case with electric and rechargeable hybrid vehicles equipped with a high-power traction battery, the vehicle is also equipped with the secondary loop 100 comprising a secondary cooling circuit 110 in which circulates a secondary fluid making it possible to transfer thermal power between the battery and the main loop by means of a heat exchanger 202 (also called a “chiller”). Heat exchanger 202 is a refrigerant-secondary fluid type exchanger. The secondary loop 100 further comprises a hydraulic pump circulating the secondary fluid, here glycol water, through a plate or tubes in contact with the thermal mass of the battery 101 in order to draw calories which are then evacuated by evaporation of the refrigerant in the heat exchanger 202. Furthermore, it is common for a secondary loop to be mounted in parallel with the heat exchanger 203 and makes it possible to circulate the refrigerant through a secondary circuit from an outlet of the heat exchanger 203 to another cabin heat exchanger and then back to the inlet of the heat exchanger.

The circulation of the secondary fluid in the loop 100 is ensured by the pump 103 whose power is controlled by means of a control signal controlled by the control unit 400 VCU. The control signal is an analog or digital signal capable of controlling the speed of rotation of the pump, defined in revolutions/minute unit for example. Identically, compressor 201 is driven by means of a command signal controlled by the 400 VCU control unit. The control signal is an analog or digital signal capable of controlling the speed of rotation of the compressor, defined in revolutions/minute unit for example. Furthermore, the thermal regulation system may include a fan 204 driven by means of a control signal controlled by the 400 VCU control unit. The control signal is an analog or digital signal capable of controlling the rotation speed of the fan, defined in revolutions/minute unit for example.

In the context of the invention, the control signals of the thermal regulation system are controlled by the control module 401 according to the instantaneous temperature of the battery and the threshold for triggering the thermal regulation operation for heating and cooling. battery. The control module comprises, recorded in memory, a map (list or table) capable of delivering several threshold values as a function of at least the value representative of said electrical power transferred.

In a first variant, for each electrical power value transferred, or for an electrical power range, a predetermined threshold value is associated. For example, from 0 to 2kW corresponds a first temperature value, from 2kW to 5kW corresponds a second temperature value lower than the first value, then so on for each electrical power range so as to cover a total range that can be between 0kW and 350kW.

As a variant, for each predetermined recharge mode, mentioned previously, there corresponds a predetermined threshold value, the temperature threshold values going in decreasing order for modes 1 to 4 respectively. It is of course envisaged that the method applies for a number of charging modes greater than four.

The different threshold values make it possible to anticipate the cooling according to the planned load. Indeed, if a load of 50kW is planned when the vehicle is connected to the terminal, then the control unit will, for example, trigger cooling as soon as a temperature of 30°C is reached to take into account the dynamics of heating of the battery in order to keep it within an acceptable range. This avoids a situation of accelerated aging and the appearance of current limitations that could delay charging.

Finally, it will be added that a module 402 is capable of providing the temperature outside the vehicle, for example a temperature sensor or any means capable of providing this data, for example a connected meteorology service. The outside temperature can affect the thermal behavior. The control unit can thus, as a variant, modify the value of the tripping threshold according to the outside temperature.

In FIG. 2, an algorithm of an embodiment of the thermal management method according to the invention is now described in the form of a synoptic graph. As indicated above, the invention proposes in particular to implement, within a vehicle, a process for thermal management of the battery intended to configure the value of the threshold for triggering the cooling/heating action of the battery. depending on the electrical power transferred between the external terminal and the battery.

This implementation can be done by means of a vehicle control unit VCU as illustrated without limitation in FIG. 1. But this is not compulsory. Indeed, the process could be implemented in a module external to the VCU control unit, while being coupled to the latter. In the latter case, the external module can itself be arranged in the form of a dedicated computer comprising a possible dedicated program, for example. Consequently, the module for implementing the thermal management method, according to the invention, can be produced in the form of software (or computer (or even “software”)) modules, or else electronic circuits (or “hardware”). ”), or a combination of electronic circuits and software modules.

At a first step 31, in accordance with the thermal management method, the control unit detects an energy transfer operation between an external charging station and the battery. The detection consists in identifying a state of the interface, a type of electrical connector used (type 1, 2, 3 or 4) to connect the charging interface to the external terminal, or even the predetermined charging mode among the modes 1, 2, 3 or 4. The data from the COM information flow between the terminal and the interface also make it possible to operate the detection. The transfer operation can be a battery charging or discharging operation.

Then, at a step 32, the control unit estimates a value representative of the electrical power transferred PE, from the flow of electrical power PE, the voltage, the type of alternating or direct voltage and the value of the reference current transiting via the interface, or from the COM data communication flow between the terminal and the interface. The value is in the first case the electrical power transferred PE, or in the second case a datum of the digital information communication flow COM between the charging station and the transfer interface representative of the electrical power available by the terminal, for example the type of electrical connector connecting the transfer interface to the terminal or a predetermined mode selected to operate the energy transfer defined by the type of voltage and the transfer security protocol (current limitation for example).

Then, prior to the triggering of the energy transfer or during the triggering of the energy transfer, in a step 33 the control unit configures the threshold for triggering the thermal regulation as a function of at least said value representative of the electrical power transferred. More specifically, the configuration step consists of determining the trigger threshold from the predetermined map. In the event of detection of a first electrical power between 1 and 2kW, or of charging mode 1, the temperature threshold is configured at a first value S1, in the event of detection of a second electrical power between 2kW and 5kW , the temperature threshold is configured at a second value S2 lower than the first value S1, and so on for each power range or recharge mode detected.

The number of thresholds defined by the mapping can be two or more. The configuration of the threshold can be updated during charging due in particular to the fact that the electrical power transferred may vary, in particular in the event of activation of a safety device imposing a current limitation or in the event of activation of a change of charging mode , or direction of energy transfer. Indeed, when discharging, the heating of a battery can be less than when charging.

As a variant, the configuration of the threshold is a function of the instantaneous state of charge of the battery and of the outside temperature. For example, for the same power, the tripping threshold can be lowered when the outside temperature is high (30°C or 40°C) or the threshold can be higher in cold weather at a temperature below 5°C.

Furthermore, the higher the state of charge value of the battery, the lower the transferable electrical power. The value of the threshold changes according to the variation in electrical power transferred.

Then, in a step 34, the transfer of electrical energy begins, charging or discharging. It is possible that the detection 31 of the energy transfer operation is operated when the charge or discharge is effective, from a flow of electrical power. In this case, steps 32 and 33 are later than the start time of the energy transfer operation.

In the event of detection in step 35 that the instantaneous temperature of the battery exceeds the triggering threshold, in a step 36, the control unit sends the control instructions triggering a cooling operation of the battery (valve control, flow pump, compressor or fan). Cooling is activated as long as the instantaneous battery temperature is above the trigger threshold.

As a variant of the method, there is optionally provided a step 37 for monitoring the end of charge, or end of discharge. Monitoring is carried out from the flow of electrical power PE or data from the communication flow COM, or the detection of the connection of an electrical connector linked to the terminal. Then, in a step 38 which is also optional, when the stopping of the load is detected, the trigger threshold, then configured at the value associated with the electrical power, is lowered by a predetermined offset value with respect to the first value of the threshold, for example by a few degrees. This offset has the effect of taking into account the inertia of the thermal power which can be induced by the electrical power, in particular when the latter is close to 50 kW or higher.

In FIG. 3, a graph has been described representing the temperature of the battery Tbat on the ordinate axis and the value of five thresholds S1, S2, S3, S4, S5 dependent on the electrical power transferred at a given instant or on the mode pre-determined charging station selected for charging. On the abscissa is represented the evolution of time during the operation of recharging the battery. For each of the electrical powers or predetermined charging modes, a signal A1, A2, A3, A4, A5 has been shown indicating the battery cooling activation time for each threshold.

Four of the five thresholds stored in the control module executing the thermal management process can each be configured by a first activation value S1a, S2a, S3a and S4a and a second deactivation value S1b, S2b, S3b and S4b of the operation cooling.

For a first charging mode corresponding to a charging power of less than 3 kW for example, the cooling trigger threshold is equal to the value S1a, here the highest temperature value. The control unit configures the value S1a as a function of thermal power, of the state of charge value of the battery and of the state of a datum indicating the detection of a charging operation (for example electrical connector connected to the outer terminal). Then once the charging operation is complete, detecting a disconnection of the electrical connector for example, the control unit configures the cooling deactivation value S1b. During the activation of the cooling associated with the first threshold (S1a, S1b) the signal A1 is active.

When the control unit detects a charging mode associated with a higher transfer electrical power, the triggering threshold is configured at lower temperature values represented here respectively in decreasing order of temperature by the values S2a, S2b, S3a, S3b and S4a, S4b.

Threshold S5 represents a configuration variant of the trigger threshold where for a predetermined electrical transfer power, the threshold value is fixed in activation and deactivation.

Claims (10)

Method for thermal management of an electric battery (101) of a battery system (300) comprising an electrical energy transfer interface (500) between the battery (101) and a charging station (600) external to the system (300) and thermal regulation means (100, 200) of the battery (101), the method comprising a step of controlling a thermal regulation operation (36) when the temperature of the battery crosses a predetermined trigger threshold (S1, S2, S3, S4, S5), the method being characterized in that it further comprises the following successive steps:

• The detection (31) of an energy transfer operation (34) between the battery (101) and the terminal (600),
• The determination (32) of a value representative of the electrical power transferred (PE) during said transfer operation,
• The configuration (33) of the trigger threshold (S1, S2, S3, S4, S5) according to said value.

Method according to Claim 1, characterized in that the configuration step (33) consists in determining the triggering threshold (S1, S2, S3, S4, S5) from a predetermined map, recorded in the memory of a control unit (400) of the thermal regulation means (100, 200), the mapping being capable of delivering several threshold values as a function of at least the value representative of said electrical power transferred. Method according to Claim 1 or 2, characterized in that the configuration (33) of the triggering threshold is also a function of the instantaneous state of charge of the battery and of the temperature of the air outside the system (300). Method according to any one of Claims 1 to 3, characterized in that the triggering threshold (S1, S2, S3, S4) is configured at a first threshold value (S1a, S2a, S3a, S4a) when transfer operation (34), then in the event of detection (37) of the end of the transfer operation, the triggering threshold (S1, S2, S3, S4) is configured at a second threshold value (S1b, S2b , S3b, S4b) lower than the first value (S1b, S2b, S3b, S4b) by a predetermined temperature offset. Method according to any one of Claims 1 to 4, characterized in that the value is the electrical power transferred (PE) between the charging station (600) and the transfer interface (500) of the system (300). Method according to any one of Claims 1 to 4, characterized in that the value is a datum of a digital information communication flow (COM) between the charging station (600) and the transfer interface (500 ) representative of the electrical power available by the terminal. Method according to claim 6, characterized in that the datum identifies a type of electrical connector connecting the transfer interface (500) to the terminal (600), or a predetermined charging mode representative of a predetermined electrical power. Method according to any one of Claims 1 to 7, characterized in that the transfer operation (34) is an operation of charging electrical energy from the battery (101) or discharging electrical energy from the battery ( 101) through the charging station (600). Control unit of a system comprising an electric battery (101), an electrical energy transfer interface (500) between the battery (101) and a charging station external to the system and means for thermal regulation of the battery ( 100, 200), characterized in that it is configured to implement the method according to any one of claims 1 to 8. Motor vehicle comprising a control unit according to Claim 9.