FR3111302A1 - ELECTRIC VEHICLE AUTONOMY MANAGEMENT SYSTEM AND METHOD - Google Patents

Abstract

The invention relates to an electric vehicle autonomy management system, depending on a state of charge of a battery (2) which can be a full state of charge for a normal mode, a critical alert state of charge for a critical alert mode, and preferably other modes for other states of charge. The autonomy management system comprises several modules including a critical alert module to alert a driver of the corresponding mode and a traction power management module configured to limit the power of the battery (2) allocated to the traction of the vehicle (3). Preferably, the power allocated to the accessories (4) is also limited in a different way, in particular cancelled, in the critical alert mode. The corresponding information (5, A, M1-M4) can be displayed on the dashboard. The invention further relates to a method and a program based on such a system. Fig. 2

Description

SYSTEM AND METHOD FOR MANAGING ELECTRIC VEHICLE AUTONOMY

The invention relates to the field of motor vehicles with electric traction motors, more particularly to systems for managing the autonomy of the battery of the electric traction motor.

With a view to reducing greenhouse gas emissions, the need to produce vehicles with electric traction motors (by simplification “electric vehicles”) has become significantly important. These vehicles include a gauge for monitoring a state of charge and an estimate of a range, that is to say a distance that can be traveled on the basis of an estimated state of charge.

In use, the dashboard of electric vehicles of the prior art generally displays an estimated range on the basis of the average energy consumption over more than ten kilometers traveled by the vehicle.

Unfortunately, such an estimate is not fully satisfactory because, being carried out over a long distance, it does not take into account a change in driver behavior or consumption of vehicle accessories. This is particularly the case for a new use of electrical accessories or the fact of taking a motorway when the vehicle was until then in built-up areas. Thus, estimation errors can lead to the risk of power failure, by simplification of "dry failure".

An objective of the present invention is to propose a vehicle autonomy management system making it possible to optimize the use of the electric battery of a vehicle over the last kilometers of autonomy in order to limit the problems of running out of fuel.

Another objective of the invention is to propose a range management system configured to perform a range estimation by limiting the estimation errors due to changes in the driver's behavior.

To achieve these objectives, the invention proposes an electric vehicle autonomy management system, on the basis of a battery charge state varying between a full charge state below which the autonomy management system enters into a normal mode, and a critical state of charge below which the autonomy management system enters a critical alert mode, the critical state of charge being less than the full state of charge, characterized in that the system includes a critical alert module to alert a driver when the battery state of charge drops below the critical state of charge, and a traction power management module configured to limit battery power allocated to vehicle traction.

The autonomy management system can be part of an on-board computer of an electric vehicle. In the context of the invention, the term "module" is understood as a set of hardware elements and program code instructions to perform a given action.

According to a first aspect, the autonomy management system further comprises an off-traction power management module configured to limit the power of the battery allocated to the off-traction electronics of the vehicle in a different way from the power of the battery allocated to vehicle traction.

The expression "battery power allocated to the traction of the vehicle" is understood as the power consumed at the input of the terminals of the electric traction machine, and that of the electronic equipment necessary to move the electric vehicle, such as the brake. The expression "non-traction power" means the power consumed by the other electronic equipment of the electric vehicle such as the charging equipment. Depending on the need for the vehicle, the power allocated to the power steering systems can be off traction or traction.

Advantageously, this configuration makes it possible to limit the power allocated to the traction motor in a different way from that allocated to the electrical accessories, for example to suppress the power allocated to the electrical accessories while limiting the power allocated to the traction motor.

In another aspect, in the critical alert mode, the traction power management module is configured to allocate sufficient battery power for predetermined performance with reference to a range cycle based on vehicle mass and the vehicle's penetration coefficient.

Advantageously, this configuration makes it possible to carry out a critical alert mode where the allocated power is sufficient for the vehicle to remain within these predetermined performances.

Preferably, the state of charge can also reach a shutdown state of charge below which the autonomy management system enters a shutdown mode, the shutdown state of charge being lower than the critical state of charge, and in the shutdown mode, the traction power management module is configured to cancel battery power allocated to vehicle traction.

According to one feature, the range management system further comprises a range estimation module configured to estimate a range of the vehicle as a function of the current state of charge and the electricity consumption of the moment.

In particular, the battery state of charge can also reach an alert state of charge below which the range management system enters an alert mode, the alert state of charge being greater than the critical state of charge and less than the full state of charge, and the range management system includes an alert module for alerting a driver when the battery state of charge drops below the alert load.

The invention further relates to a method for managing the range of an electric vehicle, on the basis of a battery charge state varying between a full charge state and a critical charge state less than the full charge state, the method comprising

• a critical alert step to alert a driver when the state of charge drops below the critical state of charge, and
• a critical power management step to limit battery power allocated to vehicle traction.

Preferably, the critical power management step is further performed to limit the battery power allocated to the non-traction electronics of the vehicle differently from the battery power allocated to the traction of the vehicle.

In one aspect, the critical power management step is further performed to allocate sufficient battery power for predetermined performance with reference to a range cycle based on vehicle mass and vehicle penetration coefficient.

Preferably, the autonomy management method further comprises a shutdown step in which, if the state of charge drops below a shutdown state of charge lower than the critical state of charge, the power of the battery allocated to the traction of the vehicle is cancelled.

According to one particular feature, the range management method further comprises a step for estimating a range of the vehicle as a function of the current state of charge and the electricity consumption of the moment.

The invention further relates to a computer program comprising program code instructions for the execution of the steps of the method according to the invention, when said program is running on a computer.

The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which:

schematically illustrates an autonomy management system in its environment in an electric vehicle; And

schematically illustrates the operation of the autonomy management system of Figure 1.

The invention relates to motor vehicles with electric traction motors. The invention relates more particularly to an autonomy management system 1 for managing the autonomy of a battery 2 of an electric motor 3.

The autonomy of the battery 2 of the electric motor 3 is estimated on the basis of a state of charge of the battery, generally designated by the acronym SOC (State of Charge). The battery 2 also supplies electronic accessories 4 other than the traction motor 3. These include the thermal equipment of the passenger compartment, the light in the passenger compartment, the sound equipment and any other comfort equipment.

The aim of the invention is to develop a function which limits the consumption of the vehicle over the last kilometers of autonomy to ensure that the driver and his passengers are not surprised by increased consumption over the last kilometres.

The aim is that the driver does not consume more energy, for example over the last 10 kilometers or so, compared to the kilometers traveled before these last 10 kilometers. Thus, the invention makes it possible to prevent the driver from being misled by the calculation of the remaining range displayed on the dashboard.

For better range management, it is preferable for the driver to be reliably informed of the range. In particular, the autonomy management system 1 comprises an autonomy estimation module S1, configured to inform of an estimated autonomy A according to the current state of charge and the electricity consumption of the moment. This is, for example, the instantaneous consumption associated with a specific calculation module for this purpose. Advantageously, the range estimation module S1 is significantly more reliable than the corresponding modules of the prior art because it is less subject to errors linked to changes in driving or in the use of vehicle electronics.

For a fully charged battery 2, a full charge state is defined, in particular a 100% charge state. Below the full state of charge, the autonomy management system 1 enters a normal mode. This mode can be illustrated by the line below SOC=100% in Figure 2.

The reference 5 in FIG. 2 designates the information given to the driver in particular via the dashboard of the vehicle.

In normal mode, the performance of the engine of the vehicle 3 is conventional performance without curbing the power of the current coming from the battery 2 to supply the motor 3. Similarly, the electrical accessories 4 of the vehicle also operate in a conventional manner without curbing the power of the current coming from the battery 2 to supply them. For example, the power of the electric vehicle battery 2 can be 75 kW or more, up to 300 kW for some utilities.

In the preferred embodiment, in the normal mode, the autonomy management system informs the driver of the autonomy A and the state of charge, in particular via a message M1 on the dashboard.

In this embodiment, an alert state of charge lower than the full state of charge, for example at a state of charge of approximately 10 to 20%, is also defined. Below the alert state of charge, the range management system enters an alert mode. This mode can be illustrated by the line below SOC=20% in figure 2. The states of charge of the different modes are preferably configurable during the tuning of the vehicle in the development phase, and can depend on the of the vehicle.

In alert mode, the performance of the vehicle's engine 3 and the consumption of accessories 4 are unchanged. The alert mode has the particularity of sending an alert to the driver to inform him of the need to recharge the vehicle. To this end, the autonomy management system 1 comprises an alert module S2 configured to alert a driver when the autonomy management system is in alert mode. For example, a message M2 provided for this purpose can be displayed on the dashboard of the vehicle, such as: "please remember to recharge your vehicle, the charge level of your battery is low".

In the preferred embodiment, in the alert mode, the message M2 further includes the state of charge and the range A is also displayed on the dashboard.

In the context of the invention, a critical alert state of charge is further defined below the full state of charge, and in the preferred embodiment, below the alert state of charge. The critical alert state of charge is for example at a state of charge of approximately 2 to 5%. This mode can be illustrated by the line below SOC=5% in Figure 2. Below the critical alert state of charge, the autonomy management system 1 enters a critical alert mode.

The invention proposes to also inform the driver of the passage to the critical alert mode, which can also be called "turtle mode". To this end, the autonomy management system comprises a critical alert module S3 configured to alert a driver when the autonomy management system 1 is in critical alert mode. To do this, an M3 message can be displayed on the instrument panel, to indicate that the vehicle's performance is reduced because of the level of charge that is too low. A “t” turtle icon can additionally be displayed on the dashboard for this purpose. Preferably, the remaining range A display is deactivated. Thus, the driver is no longer informed of the number of remaining kilometers of autonomy. This allows the driver's efforts to be focused on finding a charging station.

This critical alert mode (or "tortoise mode") is defined to limit the performance of the vehicle, limit the electrical consumption of the electric traction machine, and to alert the driver to an immediate need to recharge his power battery. The driver is alerted by the messages, the icon, and by any discomfort in his driving. This mode increases the autonomy to find a charging station in an emergency.

In the critical alert mode, the consumption of the accessories 4, and preferably the performance of the engine 3 of the vehicle are modified. To this end, the autonomy management system comprises a traction power management module S4 configured to limit the power of battery 2 allocated to the traction of the vehicle (motor 3).

In addition, the autonomy management system 1 preferably comprises an off-traction power management module S5 configured to limit the power of the battery 2 allocated to the off-traction electronics of the vehicle (accessories 4) in a different way from the power of battery 2 allocated to the traction of the vehicle. In particular, in critical alert mode, the power of battery 2 allocated to the vehicle's non-traction electronics (accessories 4) is significantly limited compared to the power of battery 2 allocated to the vehicle's traction.

Advantageously, this configuration makes it possible to limit the power allocated to the traction motor 3 in a different way from that allocated to the electrical accessories 4, for example to suppress the power allocated to the electrical accessories 4 while limiting the power allocated to the traction motor 3, by critical alert mode (or turtle mode).

Thus, the S4 traction power management module and the S5 non-traction power management module make it possible to limit the power of the current consumed over the last kilometers of range, so as not to surprise the driver and ensure that the remaining range estimate A is as accurate as possible.

The power allocated to non-traction electronics can be modified globally, or by groups of devices or by devices. In these last two cases, the modification may still be different depending on the group or device. For example, you can define a thermal unit for the passenger compartment including an air conditioning compressor and a heat pump; and a cabin audio/lighting group. Air conditioning and heating are limited as a priority to increase range.

According to another aspect, the traction power management module S4 is configured to allocate sufficient power from battery 2 for predetermined performances with reference to a range cycle according to the mass of the vehicle and the coefficient of penetration of the vehicle. (or drag coefficient, usually abbreviated Cx).

Predetermined performance is determined in range certification tests specific to the geographic areas where the electric vehicle is used. These certification tests consist, for example, of putting a 100% charged electric vehicle on a chassis dynamometer, and having the vehicle follow a succession of speeds until the vehicle can no longer follow the speeds imposed on the cycle. . The test is then stopped and the number of kilometers traveled is recorded. In particular, the performance must also allow the vehicle to reach a speed plateau of 100 km/h maximum. Over a range cycle, for a vehicle with a given mass and penetration coefficient, it is possible to determine the power to be allocated to the traction motor so that the said vehicle remains compliant with the certification tests. It is this power thus determined which is the minimum power allocated to traction motor 3 in this variant. This determination can be made via calibration maps based on the certification cycle.

Advantageously, this configuration makes it possible to carry out a critical alert mode where the allocated power is sufficient for the vehicle to remain within these predetermined performances. Thus, the critical alert mode does not disrupt the autonomy certification cycle.

In particular, the power of the battery 2 allocated to the traction of the vehicle is limited to a power limited to approximately 5 to 15% of the remaining power, for example a power comprised between 15 kW and 35 kW. This power level is preferably configurable during the development of the vehicle in the development phase and can depend on the characteristics of the vehicle. This variant of the invention allows a compromise between power limitation and compliance with the certification cycle.

Termination of the critical alert mode preferably occurs at least when the state of charge passes significantly above the critical alert state of charge. In particular, this happens when the state of charge goes above about 10 to 15%. This can happen either when the vehicle is recharged for this purpose at a charging station, or when an engine brake enables battery 2 to be recharged to the required level.

In a variant, a shutdown state of charge lower than the full state of charge and the critical alert state of charge is also defined. In the preferred embodiment, the shutdown state of charge is further lower than the alert state of charge. The shutdown state of charge is for example at a state of charge of approximately 0 to 0.5%. This mode can be illustrated by the line below SOC = 0.5% in Figure 2. Below the shutdown state of charge, the range management system enters a shutdown mode.

In this variant, the range management system also informs the driver of the switch to stop mode. To this end, the autonomy management system comprises a stop signaling module configured to signal to a driver that the autonomy management system is in stop mode. In particular, an M4 message is displayed on the instrument panel to this effect.

In the stop mode, the performance of the engine 3 of the vehicle and the consumption of the accessories 4 are canceled. To this end, the traction power management module S4 configured to cancel the power of the battery 2 allocated to the traction of the vehicle (motor 3). Additionally, the S5 off-traction power management module is configured to override battery 2 power allocated to the vehicle's off-traction electronics (4 accessories). Thus, the vehicle is immobilized until the power battery 2 is recharged.

The shutdown state of charge is preferably non-zero so as not to alter the battery 2.

The invention further relates to a method for managing the autonomy of an electric vehicle substantially comprising steps for implementing the modules and actions of an autonomy management system 1 as described previously.

In particular, the method comprises an autonomy estimation step, to inform of an estimated autonomy A according to the current state of charge and the electrical consumption of the moment.

The autonomy estimation step is preferably carried out continuously in the normal and alert modes of the autonomy management system 1 in order to display the autonomy A in these modes.

Preferably, said method further comprises an alert step when the state of charge drops below the alert state of charge. This alert step is carried out to alert a driver of the passage from the state of charge to below the alert state of charge. In particular, an alert message M2 as described previously is given to the driver, for example via a display on the dashboard. The alert step essentially corresponds to the alert mode described above.

According to the invention, said method further comprises a critical alert step to alert a driver when the state of charge drops below the critical state of charge. The message M3, the display of the turtle icon and the non-display of the range A described previously are preferably carried out.

Furthermore, according to the invention, said method further comprises a critical power management step to limit the power of the battery 2 allocated to the traction of the vehicle. This critical power management step is concomitant with the critical alert step.

Preferably, the critical power management step is also carried out to limit the power of the battery 2 allocated to the off-traction electronics, as described previously.

Additionally, the critical power management step is preferably performed to allocate enough battery 2 power for predetermined performance as previously described.

The critical alert stage and the critical power management stage essentially correspond to the critical alert mode.

According to a variant, said method further comprises a stopping step when the state of charge drops below the stopping state of charge defined previously. This stopping step is carried out to inform the driver of the stopping of the vehicle.

This step is also carried out to cancel the power of battery 2 allocated to the traction of the vehicle (motor 3) and that allocated to the electronics outside the traction of the vehicle (accessories 4).

The stop step is essentially the stop mode.

The invention further relates to a computer program comprising program code instructions for the execution of the steps of the method as described above, or for the implementation of the actions of the autonomy management system as described above. , when said program is running on a computer. The program can for example be loaded into an on-board computer of an electric vehicle.

The program comprises in particular control instructions for modifying the power allocated to the elements of the vehicle, and instructions for transmitting information to the driver, such as display instructions on the dashboard as described above.

The invention further relates to an electric vehicle comprising a range management system or a program as described herein.

Claims (10)

Autonomy management system (1) of an electric vehicle, on the basis of a state of charge of a battery (2) varying between a full state of charge below which the autonomy management system (1) enters in a normal mode, and a critical state of charge below which the autonomy management system (1) enters a critical alert mode, the critical state of charge being less than the full state of charge, characterized in that the autonomy management system (1) comprises a critical alert module (S3) for alerting a driver when the battery charge state falls below the critical charge state, and a traction power management (S4) configured to limit the power of the battery (2) allocated to the traction of the vehicle (3). Autonomy management system (1) according to claim 1, characterized in that it further comprises an off-traction power management module (S5) configured to limit the power of the battery (2) allocated to the off-traction electronics (4) of the vehicle in a different way from the power of the battery (2) allocated to the traction of the vehicle (3). Range management system (1) according to claim 1 or 2, characterized in that in the critical alert mode, the traction power management module (S4) is configured to allocate sufficient battery power for predetermined performances with reference to a range cycle as a function of the mass of the vehicle and the coefficient of penetration of the vehicle. Autonomy management system according to any one of Claims 1 to 3, in which the state of charge can moreover reach a state of charge of stop below which the autonomy management system (1) enters a mode shutdown, wherein the shutdown state of charge is less than the critical state of charge, and in the shutdown mode, the traction power management module (S4) is configured to override battery power (2) allocated to vehicle traction. Range management system (1) according to any one of Claims 1 to 4, characterized in that it further comprises a range estimation module (1) configured to estimate a range of the vehicle as a function of the current state of charge and current power consumption. Autonomy management system (1) according to any one of Claims 1 to 5, for a battery charge state which can also reach an alert state of charge below which the autonomy management system enters an alert mode, the alert state of charge being greater than the critical state of charge and less than the full state of charge, the autonomy management system (1) comprising an alert module ( S2) to alert a driver when the battery state of charge drops below the alert state of charge. Method for managing the range of an electric vehicle, on the basis of a battery charge state varying between a full charge state and a critical charge state less than the full charge state, the method comprising

• a critical alert step for alerting a driver when the state of charge drops below the critical state of charge, and
• a critical power management step to limit the power of the battery (2) allocated to the traction of the vehicle (3).

Range management method according to claim 7, characterized in that the critical power management step is also carried out to limit the power of the battery (2) allocated to the off-traction electronics of the vehicle (4) of different way of the power of the battery (2) allocated to the traction of the vehicle (3). Autonomy management method according to claim 7 or 8, characterized in that the step of critical power management is further carried out to allocate sufficient battery power for predetermined performances with reference to an autonomy cycle according to vehicle mass and vehicle penetration coefficient. A computer program comprising program code instructions for carrying out the steps of the method according to any one of claims 7 to 9, when said program is running on a computer.