WO2022238632A1

WO2022238632A1 - Method for the thermal protection of a charging device carried on board an electrified vehicle

Info

Publication number: WO2022238632A1
Application number: PCT/FR2022/050591
Authority: WO
Inventors: Olivier BALENGHIEN; Ludovic PIRES; Minh Nguyen
Original assignee: Psa Automobiles Sa
Priority date: 2021-05-10
Filing date: 2022-03-30
Publication date: 2022-11-17
Also published as: FR3122776A1; CN117426038A; EP4338252A1

Abstract

The subject of the present invention is a method for the thermal protection of a device for electrically recharging a traction battery of an electrified vehicle, wherein said recharging device is suitable for electric recharging at a terminal from the electrical mains network and for on-board electric recharging using regenerative braking, the method involving, in the event of detection (21) that a first temperature threshold (T1) has been exceeded, triggering (22) a recharging mode during which the recharging power is reduced and, in the event of detection (23) that a second temperature threshold (T2) higher than the first threshold (T1) has been exceeded, triggering (24) a recharging mode during which electric recharging at a terminal and electric recharging using regenerative braking are inhibited for a predetermined duration following the instant at which the second threshold (T2) was exceeded.

Description

1

DESCRIPTION

TITLE: METHOD FOR THERMAL PROTECTION OF AN ELECTRIFIED VEHICLE ON-BOARD CHARGING DEVICE

The present invention claims the priority of French application No. 2104914 filed on May 10, 2021, the content of which (text, drawings and claims) is incorporated herein by reference.

The field of the invention relates to a process for thermal protection of a charging device of an electrified vehicle, in particular a rechargeable motor vehicle.

Electrified vehicles, in the case of electric and rechargeable hybrid motor vehicles, comprise a traction battery, generally of high power, cooperating with electric charging means on an electrical power supply network external to the vehicle. Such vehicles are equipped with a charging device whose function is to control the charging current delivered by a terminal connected to the supply network. In addition, it is also in charge of the on-board electrical voltage conversion function. In terminal charging situations, it performs the conversion of an alternating voltage to a direct voltage (AC/DC), in particular during charging in mode 2 or mode 3 in which it is necessary to convert an alternating voltage in 220V to a compatible DC voltage of the battery system, up to 450V for example. When driving, the charging device also operates the DC/DC conversion between the battery and the vehicle's on-board systems, for example the on-board network (14V) and the electric traction machine of the powertrain.

The electrical power flows which pass through the recharging device generate a rise in temperature which it is necessary to control and evacuate in order to avoid damage to the electrical circuits and to the battery. Conventionally, known protection measures provide for limitations of the recharging current and the increase in the level of cooling in the event of exceeding critical temperatures. The document FR2999812A3 is known in particular describing a cooling system optimized for so-called fast loads comprising two circuits of 2 circulation of heat transfer fluid. The document CN109378536A is also known describing the charging and discharging management of an electrified vehicle battery.

It is necessary to improve the existing thermal protection solutions. One objective of the invention is to guarantee the integrity of the charging device for all situations of use of the vehicle, charging at a terminal and while driving. Another objective is to improve the thermal monitoring of the charging device of an electrified vehicle and to manage protective measures for each situation likely to lead to a critical temperature rise.

More specifically, the invention relates to a process for thermal protection of an electric charging device for an electrified vehicle traction battery in which said charging device is suitable for electrical charging at a terminal from a network of electric power supply and on-board electric recharging by regenerative braking, the method comprising the following steps of triggering a first mode of recharging the battery, continuously measuring the temperature of said recharging device, and in the event of detection of the overflow of a first temperature threshold, the triggering of a second charging mode during which the charging power is reduced relative to the power of the first mode.

According to the invention, the method further comprises, in the event of detection of the exceeding of a second temperature threshold greater than the first threshold, the triggering of a third charging mode during which the electrical charging on terminal and the electrical charging by braking recuperative are inhibited for a predetermined duration following the instant of exceeding the second threshold.

According to a variant, the second charging mode consists in reducing the charging power gradually according to the increase in temperature up to a temperature limit.

According to a variant, in the event of detection of a temperature of the charging device which is greater than a third temperature threshold after the expiry of the predetermined duration, the inhibition of the electrical charging on the terminal permanently and the recording a diagnosis of thermal failure.

According to a variant, it also comprises the inhibition of electric recharging by regenerative braking as long as the temperature is above the third threshold. 3

Preferably, the third threshold is lower than the first threshold.

According to the method, in the event of detection of a temperature of the charging device which is lower than a fourth temperature threshold before the expiry of the predetermined duration, the method comprises the reactivation of the electrical charging on the terminal and the electrical charging by regenerative braking.

According to a variant, the third charging mode further comprises the control of a set point of an on-board thermal regulation system so as to increase the level of cooling of said system.

According to a variant, the setpoint controls the speed of a ventilation device and/or the speed of a hydraulic pump and/or the valve opening of a hydraulic circuit.

The invention provides an electrified vehicle powertrain comprising a traction battery, a device for electrically recharging said traction battery in which said recharging device is suitable for electrical recharging at a terminal from an electrical power supply network and to on-board electrical charging by regenerative braking, in which a control unit is configured to implement the thermal protection method according to any one of the preceding embodiments.

The invention provides an electrified vehicle comprising such a powertrain.

The method guarantees the integrity of the charging device and aims to avoid thermal operating conditions where electrical charging takes place in degraded mode. In particular, in charging stations and regenerative braking, it allows you to return to normal operating conditions.

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:

[Fig.1] schematically represents an electrified vehicle comprising a control unit capable of implementing the method according to the invention;

[Fig.2] represents a flowchart illustrating an algorithm of the thermal protection method according to the invention. 4

The invention applies to electrified vehicles, in particular rechargeable, hybrid and electric motor vehicles.

In Figure 1, there is shown an example of an electrified vehicle 1 capable of implementing the invention. The vehicle 1 comprises a powertrain fitted with a control unit 2, an electric traction machine (not shown) powered by a traction battery system 3 and a battery charging device 4.

The battery system 3 comprises a high voltage electric battery, generally of several hundred volts, for example 450V, ensuring the supply of electric power to the electric machine. The electric battery comprises electric cells, for example of the Lithium-ion type. The battery system 3 includes a battery system management computer.

The charging device 4 comprises charging means cooperating with a power socket 6 so as to be able to be electrically connected to an external charging terminal 7 connected to an electrical power supply network 8. It is in charge of managing the communication between the different charging stations and to monitor and control electric charging at the station. The recharging device 4 also comprises an electrical converter of the alternating/direct AC/DC and direct/direct DC/DC type. A first function is to convert an alternating voltage delivered by the charging terminal 7 into a compatible direct voltage of the battery. According to the charging mode, the charging device drives a charging setpoint defining a charging voltage and a compatible charging current of the battery. The charging power can be controlled by the charging device 4 according to various parameters and instructions. In the context of the method according to the invention, the temperature of the recharging device 4 is a recharging power control parameter. According to a second function, the charging device 4 is also provided for converting electrical voltages between the on-board systems of the vehicle, in particular between the high voltage battery 3 and the on-board network, of around 14V, and between the high voltage battery 3 and the electric traction machine, when driving and in regenerative braking.

To ensure the thermal protection of the battery 3 and of the recharging device 4, the powertrain also comprises a thermal regulation system 5 of the on-board electrical systems, the level of cooling of which is adjustable by the thermal protection method according to the invention. In this non-limiting example, the 5 thermal regulation system 5 is a circuit of the loop type with thermodynamic cycle consisting of a main cooling circuit with heat transfer fluid and heat exchange elements. It may include secondary water cooling circuits and mechanical ventilation means depending on the cooling architecture. In this example, the thermal regulation system 5 comprises means for controlling the flow rate of the heat transfer fluid, in particular a pump and hydraulic valves, and means for controlling the operating speed of the fans. These control means, which can be controlled by a computer, make it possible to adjust the level of cooling desired at the level of the battery 3, of the recharging device 4 and of the other electronic components to be thermally controlled in accordance with the method according to the invention.

The control unit 2 is equipped with an integrated circuit computer and electronic memories and is configured to control the thermal protection method of the charging device according to the invention, but also other functions of the powertrain, such as electric traction, charging by regenerative braking, the thermal regulation system and the charging device. The computer could be external to the control unit 2, while being coupled to the latter. In the latter case, it can itself be arranged in the form of a dedicated computer comprising a possible dedicated program, for example. Consequently, the control unit, according to the invention, can be produced in the form of software (or computer (or even “software”)) modules, or else of electronic circuits (or “hardware”), or even of a combination of electronic circuits and software modules.

In Figure 2, there is shown an embodiment of the thermal protection method according to the invention. The thermal protection process aims to protect the electrical components during the generation of electrical flows between the charging device and other on-board components of the vehicle. The method provides for the continuous measurement of the temperature T of the recharging device at each instant to control the various recharging modes and the thermal protection measures.

At a step 20, we are in a situation of life of the vehicle where an electric recharge is triggered. This is either charging at a charging station or regenerative braking type driving charging. An electrical flow is generated at the recharging device. Recharging is carried out according to a first mode at an electrical power 6 recharge depending on the type of recharge. For example, in terminal charging, the charging power can be 7 kW, 11 kW or more in so-called ultra-fast charging. In regenerative braking, the recharging power depends on the braking torque and the power of the electric traction machine. The thermal regulation system is controlled at a default cooling level, depending on the cooling strategy of the charging modes. For example, the speed of the hydraulic pump is controlled at a value of 20% to 30% of the maximum setpoint level, the speed of the fans is controlled at a value of 20% to 30% of the maximum level and the opening of the dampers of the hydraulic circuit at an opening of 70% of the maximum opening. These values are cited by way of non-limiting example and depend on the architecture of the vehicle's on-board thermal regulation system.

At a step 21, the method includes monitoring the instantaneous temperature T of the recharging device with respect to a first threshold T1, for example configured at 120 degrees Celsius. In the event of detection that the temperature threshold T1 has been exceeded, the method comprises, in a step 22, the triggering of a second charging mode at degraded power, during which the charging power is reduced compared to the power of the first controlled mode at step 20. This protective measure is known and generally aims to prevent damage to the battery. This degraded charging mode is controlled by the charging device by sending a charging instruction to the charging station consisting in limiting the charging current.

According to a variant of the method, the recharging power is gradually reduced as a function of the increase in temperature up to a limit Tmax, for example a value of 130 degrees Celsius. For example, the power reduction is linear and is controlled according to the following relationship: Pd = Pn x (Tmax-Tx) / (Tmax-T1 ), where Pd is the charging power in degraded mode after the time of overrun of the threshold T1 , Pn is the charging power in nominal mode prior to the time of overrun of T1 , Tmax is the temperature limit in control at reduced power, T1 is the value of the temperature of the triggering threshold of the charging mode degraded.

In another variant, the recharging power is limited to a fixed power, lower than the recharging power controlled before the instant of exceeding the threshold T1. 7

A thermal evaluation is carried out continuously during a step 23 after the instant of exceeding the first threshold T1. In the situation where the temperature rise continues, and in the event of detection of the exceeding of a second temperature threshold T2, of a value greater than the first threshold T1, the recharging device pilots at a step 24 the triggering of a third mode recharging configured to ensure the execution of several protective measures. In a terminal charging situation, electrical charging is inhibited for a predetermined inhibition period Din following the instant of exceeding the second threshold T2. In a driving situation, electrical charging by regenerative braking is inhibited for the predetermined inhibition period Din following the instant of exceeding the second threshold T2. The predetermined inhibition duration is equal for example to 10 seconds. T2 is for example between T1 and Tmax, or can be equal to or greater than Tmax.

Furthermore, preferably at step 24, the third charging mode is configured to increase the level of cooling applied by the thermal regulation system to the charging device simultaneously with the charging inhibition. Preferably, the cooling level is increased to the maximum level. To this end, the recharging device controls a setpoint for increasing the speed of the hydraulic pump of the heat transfer fluid circuit, preferably at maximum speed, a setpoint for increasing the opening of the cooling valves of the hydraulic circuit, preferably at the maximum opening section, and a fan speed increase setpoint, preferably at maximum speed. These measures are cited by way of non-limiting example and depend on the architecture of the vehicle's on-board thermal regulation system. Other instructions can be envisaged by the method according to the invention.

When the inhibition period Din has elapsed, a new thermal evaluation 25 is carried out by the protection method.

In the situation where the temperature of the charging device is lower than T1 but still higher than a third threshold T3 at the time of end of the inhibition duration Din, for example 115 degrees Celsius, the method further comprises in a step 26, the permanent inhibition of electric charging at the terminal and the recording of a diagnosis of thermal failure in a failure log. This inhibition is maintained for the charging phase on charging station in progress. In a situation of 8 rolling, in step 26, the regenerative braking function is inhibited until the temperature of the charging device has not dropped below the third threshold T3. Preferably, in order to restore acceptable thermal conditions, whether for the situation of recharging on terminal or for a driving situation, the instructions for increasing the level of cooling controlled during step 24 remain active. Preferably at the maximum cooling level. Furthermore, it is envisaged in a variant of step 26 that an alert signal be generated to warn the driver. This signal indicates that a thermal fault has been detected and that a garage check is required. The alert may appear as a warning light on the dashboard. The alert is generated simultaneously with the recording of the diagnosis in the fault log.

Alternatively, in the situation where the temperature of the recharging device has decreased more sharply, the temperature becoming equal to or lower than a fourth threshold T4 at the time of end of the inhibition duration Din, the method, at a step 27, authorizes a reactivation of the recharge. Preferably, the threshold T4 is equal to the threshold T3, or may be lower than T3. Under these thermal conditions, during step 27, in the event of charging at the terminal, the charging device again authorizes electrical charging at the terminal at normal charging power, identically to step 20. In a driving situation, electrical charging by regenerative braking is permitted. Furthermore, the thermal regulation system returns to normal operating parameters. The hydraulic pump speed, damper opening and fan speed setpoints are controlled at default cooling level values, identical to the values controlled during step 20.

Claims

9

CLAIMS Process for thermal protection of an electric charging device for an electrified vehicle traction battery, in which said charging device is suitable for electrical charging at a terminal from an electrical power supply network and for electrical charging on board by regenerative braking, the method comprising the following steps:

- triggering (20) of a first battery charging mode,

- permanently measuring the temperature of said recharging device,

- in the event of detection (21) of the exceeding of a first temperature threshold (T1), the triggering (22) of a second charging mode during which the charging power is reduced compared to the power of the first mode,

- characterized in that it further comprises, in the event of detection (23) of the exceeding of a second temperature threshold (T2) greater than the first threshold (T1), the triggering (24) of a third charging mode during which the electrical charging at the terminal and the electrical charging by regenerative braking are inhibited for a predetermined duration (Din) following the instant of exceeding the second threshold (T2). Thermal protection method according to Claim 1, characterized in that the second mode of recharging consists in reducing the recharging power gradually as a function of the increase in temperature up to a temperature limit (Tmax). Thermal protection method according to Claim 1 or 2, characterized in that it further comprises, in the event of detection of a temperature (T) of the recharging device (4) which is greater than a third temperature threshold (T3 ) after the expiry of the predetermined duration (Din), the inhibition (26) of the electrical charging on the terminal permanently and the recording of a diagnosis of thermal failure. Thermal protection method according to Claim 3, characterized in that it further comprises the inhibition (26) of electrical charging by regenerative braking as long as the temperature (T) is above the third threshold (T3). 10 Thermal protection method according to claim 3 or 4, characterized in that the third threshold (T3) is lower than the first threshold (T1). Thermal protection method according to any one of claims 1 to

5, characterized in that in the event of detection of a temperature of the recharging device which is lower than a fourth temperature threshold (T4) before the expiry of the predetermined duration (Din), the method comprises the reactivation (27 ) electric charging at terminals and electric charging by regenerative braking. Thermal protection method according to any one of claims 1 to

6, characterized in that the third charging mode further comprises the control of a setpoint of an on-board thermal regulation system (5) so as to increase the level of cooling of said system (5). Thermal protection method according to Claim 7, characterized in that the setpoint controls the speed of a ventilation device and/or the speed of a hydraulic pump and/or the opening of the valve of a hydraulic circuit. Electrified vehicle powertrain comprising a traction battery, an electric recharging device for said traction battery in which said recharging device is suitable for electric recharging at a terminal from an electric power supply network and for electric recharging on-board by regenerative braking, characterized in that it comprises a control unit configured to implement the thermal protection method according to any one of Claims 1 to 8. Rechargeable electrified vehicle comprising a powertrain according to Claim 9.