FR3073189A1 - METHOD FOR MANAGING THE ELECTRICITY OF TRACTION FOR A MOTOR VEHICLE - Google Patents

Abstract

The invention relates to a method for controlling a vehicle powertrain (1) for the management of electric traction power, said vehicle comprising at least one electric traction machine (12) powered by a traction battery (14). the vehicle being operable in at least a first and a second traction mode, the method comprising configuring a first and second permitted maximum electrical power level consumable by the electric traction machine (12) when the vehicle operates in the first and second pull mode respectively. The method consists in delaying the instant of modification of the first level towards the second level after the instant of tripping of the passage from the first to the second mode of traction until the detection of at least one condition allowing said modification. The invention applies to electric motor vehicles, or electric hybrids.

Description

The field of the invention relates to a method of controlling a vehicle powertrain for managing the electric traction power.

Motor vehicles with hybrid electric motorization can comprise several traction machines allowing the operation of several vehicle driving modes, for example an all-electric traction mode, commonly designated by the acronym ZEV for “Zero Emissions Vehicle”. in English and a hybrid traction mode. Each traction mode requires a specific operating configuration in order to optimize the vehicle's energy consumption in particular. In the case of an electric hybrid vehicle comprising an electric traction machine cooperating with a thermal combustion engine, it is common to configure different levels of maximum electric power consumable by the electric traction machine according to the selected traction mode. For example, in ZEV traction mode, the vehicle supervisor or the traction battery management system authorizes a level of electric traction power which is generally higher than the power level configured for hybrid traction mode. This energy strategy makes it possible to reduce electricity consumption due to the availability of the heat engine.

However, during a transition from one traction mode to another, the modification of the authorized level of maximum electrical traction power can cause an unwanted feeling of loss of power. Known energy management strategies aim to solve the problems of torque breakdown during a transition from traction mode. Document FR3044993_Al, for example, is known which describes a solution proposing a reserve of power delivered during a transition from one traction mode to another. However, the reserve reduces the traction power performance of the vehicle during ZEV driving.

The invention provides an improved energy management solution to prevent torque breakdowns during a change of traction mode while maintaining acceptable performance of electric traction.

More specifically, the invention relates to a method of controlling a vehicle powertrain for managing the electric traction power, said vehicle comprising at least one electric traction machine powered by a traction battery, the vehicle capable of operating in at least a first and a second traction mode, the method comprising the configuration of a first and a second authorized level of maximum electric power consumable by the electric traction machine when the vehicle is operating in the first and the second mode of traction respectively. According to the invention, the method is remarkable in that it consists in delaying the instant of modification from the first level to the second level after the instant of initiation of the passage from the first to the second traction mode until detection at least one condition authorizing said modification.

According to a variant, the modification of the first level towards the second level is only authorized in the event of detection of the flow of a predetermined duration after the instant of initiation of the passage from the first to the second mode of traction.

According to another variant, the modification from the first level to the second level is only authorized in the event of detection of the end of the passage from the first to the second traction mode. More specifically, two variants of detection of the end of the passage from the first to the second traction mode can be provided. In a first variant, the end of the passage from the first to the second traction mode is detected when a procedure for starting a second traction machine is completed, and in a second variant, the end of the passage from the first to the second traction mode is detected when, in addition, a torque transmission operation of a coupling member connected to the output shaft of the second traction machine is completed.

According to a variant of the method, the first authorized level of maximum electrical power consumable by the first traction machine is greater than the second authorized level.

According to the invention there is provided a motor vehicle comprising a powertrain controlled by a control device, in which the control device is configured to implement the method according to any one of the preceding embodiments.

The time shift of the modification of the authorized level of electric traction power by the control method makes it possible to avoid a torque break during the transition from the change of traction mode. Driving pleasure is thus improved, because a drop in vehicle speed is thus avoided, in particular when switching from an all-electric traction mode to a hybrid traction mode.

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

Figure 1 is a schematic representation of a hybrid vehicle powertrain capable of implementing the method according to the invention;

FIG. 2 represents an energy management module of the powertrain configured to implement the method according to the invention;

FIG. 3 is a graph representing the authorized levels of electrical power configured by the method according to the invention during a transition from a ZEV traction mode to a hybrid traction mode for the powertrain of FIG. 1.

FIG. 1 illustrates the powertrain 1 of a motor vehicle comprising an electric hybrid powertrain comprising a thermal traction motor 10, a coupling member 11 of clutch type connecting the thermal traction motor 10 and the primary shaft of a gearbox 13. In addition, an electric traction machine 12 is coupled to the primary shaft of the gearbox in order to provide electric traction power. A traction battery 14 is also provided, supplying electric power to the electric traction machine 12. The level of maximum electric power deliverable to the electric traction machine 12 by the traction battery 14 for the electric traction power is configurable as a function one or more information signals representative of the operation of the powertrain.

The powertrain 1 also includes a control device 15 configured to implement control functions of the powertrain, in particular the electrical energy management functions of the powertrain. The control device 15 can consist of a centralized control unit composed of a computer with integrated circuits, commonly called ECU for "Electric Control Unit" in English or supervisor, or of several control modules which can be distributed between several organs powertrain, such as the internal combustion engine, gearbox or battery management system.

[014] In particular, as illustrated in FIG. 2, the invention provides a module 20 for managing the electric traction power in charge of determining the authorized level of the maximum electric traction power of the vehicle consumed by the electric machine of traction. The authorized level of the maximum power is configurable according to at least two predetermined levels PMI, PM2, each of the predetermined levels being associated specifically with a mode of traction of the vehicle. The arbitration between the authorized levels is determined as a function of at least one information signal Smtr representative of the selected traction mode of the vehicle.

Preferably, the arbitration is also a function of an information signal Ssoc representative of the state of charge level of the traction battery in order to adapt the electrical consumption according to the available electrical energy reserve. Other parameters can be considered for arbitration, such as parameters inherent in the operation of the traction battery or Sgmp parameters inherent in the operation of the powertrain, such as the ignition state of the heat engine or a value of engine torque that can be generated by other powertrain traction machines if necessary.

In particular, the signal Smtr is transmitted by a control interface 21 for the selection of the vehicle driving modes. In this configuration, the motor vehicle can be configured in at least a first ZEV traction mode in which the traction power of the vehicle is supplied only by the electric traction machine and a second so-called hybrid traction mode in which the traction power of the vehicle can be supplied by the electric traction machine and the heat engine simultaneously. Other driving modes can be provided and informed by the Smtr signal, such as a so-called sporty traction mode maximizing driving performance by means of the available traction machines, or a so-called economical traction mode, favoring the reduction of energy consumption in relation to driving performance. The invention can be applied to vehicles having other driving modes. The control interface 21 can be manipulated by the driver by means, for example, of a selection button, a touch screen or a software context menu, allowing the driver to choose a desired traction mode.

It will be noted that the management module 20 is able to detect the triggering of the transition to the hybrid traction mode from the signal Smtr transmitted by the command interface and / or from the Sgmp parameters, in particular when a request for ignition of the engine is activated. Hybrid traction can be triggered manually by the driver or automatically by a drive program for the powertrain control device. In addition, the management module 20 is able to detect the end of the transition to the hybrid traction mode HY, that is to say the instant from which the heat engine is available to provide traction power to the wheels.

Furthermore, the signal Ssoc is transmitted by a management module 22 of the traction battery and is capable of transmitting any type of information relating to the operation of the traction battery by means of the information signal Ssoc, in particular the state of charge of the battery. It is also expected that the management module 20 can receive any type of information relating to the operation of the powertrain by means of the information signal Sgmp from a control module 24 or communication bus.

More specifically, the management module 20 of the electric traction power is capable of transmitting a setpoint (of the power limitation instruction type or information signal) CSmax_mel to a control module 23. The setpoint CSmax_mel is representative an authorized level of the maximum electric power consumable by the electric traction machine from the energy of the traction battery of the vehicle at a given time of travel. The authorized level is chosen from at least two predetermined levels PMI, PM2.

Furthermore, the control module 23 is responsible for controlling the electric traction machine from instructions, such as speed instructions, engine torque instructions, or braking torque instructions. The CSmax_mel setpoint transmitted to the module 23 therefore determines the operating ranges of the electric traction machine in order to respect the maximum authorized electric power.

[021] For example, an energy management strategy may provide that, when the ZEV traction mode is selected, the electric power consumable by the electric traction machine is configured at an authorized level of 50 kW, while when the hybrid traction is selected, the electric power consumable by the electric traction machine is configured at a lower authorized level, for example 40 kW, due to the availability of thermal traction and to reduce the electric consumption of the powertrain. These values are given by way of example and in no way limit the invention.

[022] We will now describe from FIG. 3 the application of the control method for the management of the electric traction power for the powertrain described in FIG. 1. Information signals of the powertrain are represented graphically along of a time abscissa axis. On the ordinate axis are shown the power values for the traction of the vehicle expressed in kW. A first signal CSmax_mel is represented in dotted line and indicates the authorized level of maximum electrical power for electric traction, a second signal CSmax_mth is represented in dotted line of greater length and indicates the authorized level of maximum power for thermal traction and a third signal Pmax_TRtot is shown in full gear and indicates the authorized level of maximum total power for the traction of the vehicle. Two maximum power values are shown on the ordinate axis.

[023] In this example, the powertrain control method configures a first PMI level of maximum power for electric traction (50 kW in this case) specifically assigned for the ZEV traction mode and configures a second PM2 level ( 40kW) of maximum power for electric traction specifically assigned for the HY hybrid traction mode. More specifically, the driving situation represented in FIG. 3 begins with an operation of the vehicle configured in ZEV traction mode and illustrates a transition from ZEV traction mode to hybrid HY traction mode. In this scenario, it is specified that when the traction mode ZEV is activated before time tl the electric traction machine operates at the maximum electrical power level PMI.

According to the invention, the powertrain control method for managing the electric traction power consists in delaying the instant t2 of modification of the first PMI level towards the second PM2 level after the triggering instant tl of change from ZEV traction mode to HY traction mode until at least one condition authorizing the modification is detected. This avoids the possibility of a torque break during the transition of the traction modes in the event of electric driving operated at the maximum power authorized for the electric machine.

To fulfill this objective, the method firstly comprises the detection of the triggering of the transition from the traction mode ZEV to the hybrid traction mode at time tl, from the information signals Smtr and / or Sgmp information signals. Triggering of the change of traction mode can be done manually by the driver from the driving mode control interface, or automatically by a powertrain control module, such as the combustion engine control module or a vehicle energy strategy supervision module. The method then comprises modifying the authorized level of electric power for the electric traction machine as a function of one or more detection conditions. These detection conditions are specifically attributed to the modification of the authorized level so as to allow a time difference and the availability of alternative traction power, in the case of powertrain 1 it is thermal traction power.

[026] According to a first variant of the method, the modification of the first level PMI to the second level PM2 is only authorized in the event of detection of the flow of a predetermined duration D after the instant tl. The predetermined duration D is configured in vehicle design and the control of the flow of the duration D is implemented by a timer for example. The modification of the signal CSmax_mel from the first level PMI to the second authorized level PM2 of maximum electrical power is applied at time t2 when the duration D has elapsed.

There is therefore no torque break during the transition from the traction mode ZEV to the traction mode HY between the instants tl and t2.

[027] For this hybrid powertrain architecture, the predetermined duration D is configured as a function of an estimate of the time necessary to execute the procedure for starting the heat engine and to complete the torque transmission operation of the clutch connecting the heat engine to the gearbox, for example between a few hundred milliseconds up to 2 seconds generally. However, to guarantee the availability of the traction power, the predetermined duration D may be equal to or greater than the time necessary to execute the starting procedure and the torque transmission operation of the heat engine.

In a variant of the method, in order to guarantee the availability of the thermal traction power, the modification of the authorized level of maximum electric power is only authorized in the event of detection of the end of the transition from the ZEV traction mode. towards hybrid traction mode. More specifically, the end of the transition from traction mode corresponds to a predetermined state of operation of the powertrain in which the heat engine is in a situation of torque transmission to the wheels. This state is detectable from information signals from the powertrain, such as the operating state of the heat engine in the on and running conditions and the clutch in the locked state.

[029] Indeed, it is conceivable that the predetermined duration D does not synchronize in all driving situations with the instant of supply of the thermal traction power to the wheels. This is the case, for example, if the start-up procedure of the heat engine is triggered at a time lag tl, or is delayed for an exceptional cause.

A variant of the method is therefore provided to resolve this particular situation. In accordance with the architecture of the powertrain described in FIG. 1, in a first detection function, the end of the transition from the traction mode ZEV to the hybrid traction mode HY is detected when the procedure for starting the engine of the powertrain is completed. The starting procedure is considered to have ended when the crankshaft of the heat engine has reached the speed and / or torque necessary to drive the vehicle to the driver's set speed. The control method thus ensures compliance with one of the conditions necessary for the thermal engine to be able to transmit thermal traction power and thus delays the triggering of the command to modify the authorized level of maximum electrical power after the instant. tl.

[031] In addition, in another variant of the method, according to a second detection function, the end of the transition from the traction mode ZEV to the hybrid traction mode HY is detected when, in addition, a torque transmission operation of the clutch is complete. This event is detectable from information signals representative of the operating state of the clutch and delays the triggering of the command to modify the authorized level of maximum electric power after time tl.

[032] Preferably, the first authorized level PMI of maximum electrical power consumable by the first traction machine in ZEV mode is greater than the second authorized level PM2 in hybrid mode. The difference in level makes it possible to reduce the electric consumption of the hybrid vehicle due to the availability of the internal combustion engine.

It will be specified that the modification of the authorized level can be conditioned only by the detection of the flow of the predetermined duration D after the moment of initiation of the transition from traction mode, or only by the detection of the end of the passage of the traction mode controlled, or by the realization of said two detection conditions at the same time.

We have described in Figure 3 the transition from a ZEV traction mode to a hybrid traction mode. However, the method can be applied for other changes of traction mode, for example from a ZEV traction mode to an economical traction mode or any other traction mode having an authorized level of electric traction power different from the initial traction mode, and always in the event that the authorized level of electric traction power differs from one traction mode to another.

In addition, the application of the method has been described for a hybrid powertrain in accordance with FIG. 1. However, the invention applies to other hybrid architectures providing for several traction modes having respectively specific authorized levels electric traction power. The method also applies to electric vehicles having one or more electric traction machines requiring a transition for the change of traction mode, and always in the event that the authorized level of electric traction power consumable by an electric machine differs from one mode of traction to another. In the case of an electric vehicle, a mode of traction can differ from another mode of traction when the number of electric traction machines participating in the movement of the vehicle differs between the two modes, for example if the powertrain of the vehicle has two independent traction trains in transmission.

Claims (7)

1. Method for controlling a vehicle powertrain (1) for managing the electric traction power, said vehicle comprising at least one electric traction machine (12) powered by a traction battery (14), the vehicle able to operate according to at least a first and a second traction mode (ZEV, HY), the method comprising the configuration of a first (PMI) and a second level (PM2) authorized of maximum electrical power consumable by the machine electric traction (12) when the vehicle is operating in the first (ZEV) and the second traction mode (HY) respectively, the method being characterized in that it consists in delaying the instant (t2) of the modification of the first level (PMI) towards the second level (PM2) after the instant (tl) of triggering the passage from the first (ZEV) to the second traction mode (HY) until the detection of at least one condition authorizing said modification. 2. Method according to claim 1, characterized in that the modification of the first level (PMI) to the second level (PM2) is only authorized in the event of detection of the flow of a predetermined duration (D) after the instant (tl) of triggering the passage from the first (ZEV) to the second traction mode (HY). 3. Method according to claim 1 or 2, characterized in that the modification of the first level (PMI) to the second level (PM2) is only authorized in the event of detection of the end of the passage from the first (ZEV) to the second mode of traction (HY). 4. Method according to claim 3, characterized in that the end of the passage from the first (ZEV) to the second traction mode (HY) is detected when a procedure for starting a second traction machine (10) is completed . 5. Method according to claim 4, characterized in that the end of the passage from the first (ZEV) to the second traction mode (HY) is detected when in addition an operation of transmitting torque from a coupling member (11) connected to the output shaft of the second traction machine (10) is completed. 6. Method according to any one of the preceding claims, characterized in that the first level (PMI) authorized of maximum electrical power consumable by the first traction machine (12) is greater than the second level (PM2) authorized. 7. Motor vehicle comprising a powertrain (1) controlled by a control device (15), characterized in that the control device (15) is configured to implement the method according to any one of the preceding claims.