FR3106550A1 - ENERGY MANAGEMENT PROCESS ON A KNOWN ROUTE OF A THERMAL / ELECTRIC DRIVE CHAIN IN A HYBRID VEHICLE ESPECIALLY OF THE RECHARGEABLE TYPE - Google Patents

Abstract

The method comprises a planning of a taxiing of the hybrid vehicle on a known route from data provided by a navigation system (NAV) of the vehicle and an activation of a heat engine of the hybrid vehicle for a propulsion thereof when a requested wheel power (Pdem) becomes greater than a power threshold (Pztep). According to the invention, the method comprises a regulation of a ratio (Ke) between an available electrical energy (Ed) and an electrical energy requirement (Eb) for the propulsion, the power threshold being determined as a function of the ratio of way to achieve regulation. Fig.1

Description

METHOD FOR ENERGY MANAGEMENT ON A KNOWN COURSE OF A THERMAL/ELECTRIC PROPULSION TRACTION CHAIN IN A HYBRID VEHICLE IN PARTICULAR OF THE RECHARGEABLE TYPE

The invention generally relates to the field of energy management of a traction chain with thermal/electric propulsion in a hybrid land vehicle. More particularly, the invention relates to a method of energy management over a known route of a traction chain with thermal/electric propulsion in a hybrid vehicle, typically a plug-in hybrid vehicle, but not exclusively.

Rechargeable hybrid vehicles called "PEHV", for "Plug-in HybridElectric Vehicle" in English, comprise a traction battery pack which is rechargeable by connection to an external electrical source such as the AC power supply network. These vehicles benefit from several modes of propulsion, namely, thermal propulsion consuming gasoline or diesel fuel, electric propulsion consuming electrical energy drawn from the traction battery pack and mixed thermal/electric propulsion. The ability to recharge the traction battery pack from the AC power supply network allows greater use of electrical energy for vehicle propulsion. The result is a vehicle with increased performance in terms of reducing pollutant emissions, such as CO2, and which remains capable of driving beyond electric range alone thanks to thermal propulsion. When driving in electric propulsion mode, if the distance to be covered by the hybrid vehicle is greater than its electric range, the internal combustion engine must contribute to the propulsion of the vehicle. An energy management strategy must then decide on the sections of the route on which to activate the thermal propulsion mode.

Energy management strategies for the powertrain of the hybrid vehicle have been proposed, in particular on a route known in advance, to make the best use of the three available propulsion modes. At any time, the energy management strategy must be able to decide which propulsion mode to activate.

In general, a rotating electrical machine has better efficiency for low powers, unlike a heat engine whose efficiency is better for high powers. In order to minimize fuel consumption, the energy management strategy could decide to activate the internal combustion engine when the power requested from the traction chain exceeds a certain power threshold. However, the problem arises of the choice of a value for this power threshold.

The energy management strategy must make it possible to preserve the electrical energy of the traction battery pack so that it can be used throughout the journey, when its use is optimal in terms of energy efficiency, CO2 reduction or economic profitability. In addition, driving of the vehicle in electric propulsion mode can be imposed in controlled traffic areas.

The vehicle must be able to be propelled in electric mode in all areas of the route that require low traction power. For this, it is necessary to have usable electrical energy for the propulsion in the traction battery unit until the end of the course. On the other hand, once the journey has been completed, there must not be any electrical energy available in the traction battery unit, otherwise this means that fuel savings have not been made. The available electrical power remaining in the traction battery pack should have been used to save fuel.

Proper optimization of energy management requires that the usable electrical energy for propulsion in the traction battery pack be substantially equal to zero once the journey is completed. To be able to achieve such an optimization, the energy management strategy must know precisely the energy requirement along the route. Car navigation systems provide information such as trip distance, average speed and possibly a breakdown of a trip between city, road or motorway driving. However, these systems do not make it possible to know in advance the energy required to complete a course. In fact, the energy required for the route will depend on the traffic, on elements not indicated such as traffic lights and stops and, above all, on the driving style of the driver of the vehicle.

In the state of the art, there is a function known as "GEPC", for "Energy Management on Known Route", which is typically hosted in a hybrid power train supervisor computer. The “GEPC” function roughly estimates the energy requirement over a known route, generally using maps. However, the estimate provided by the “GEPC” function is not sufficiently precise. This results in suboptimal energy management, with a traction battery pack in which there is often a quantity of energy available that has not been used during the journey.

Document FR3037025A1 discloses a method for controlling the discharge of a hybrid vehicle traction battery pack during a planned route comprising a controlled traffic zone in which electric driving is imposed. The method includes calculating the planned route and reserving, before the execution of the planned route, a depth of discharge of the traction battery pack for driving only in the electric propulsion mode in the controlled traffic zone. No decision strategy for activating the heat engine during the journey is described in this document FR3037025A1.

It is desirable to provide a method that does not have the aforementioned drawbacks of the prior art and capable of providing optimal energy management over a known route of the traction chain of a plug-in hybrid vehicle.

According to a first aspect, the invention relates to a method for energy management on a known route of a traction chain with thermal/electric propulsion in a hybrid vehicle, the method comprising a planning of a rolling of the hybrid vehicle on the known route from data supplied by a navigation system of the vehicle and an activation of a thermal engine of the hybrid vehicle for propulsion of the latter when a power at the requested wheel becomes greater than a power threshold. In accordance with the invention, the method comprises a regulation of a ratio between an available electric energy and a need for electric energy for the propulsion, the power threshold being determined as a function of the ratio so as to obtain the regulation.

According to a particular characteristic, the power threshold is determined using a mapping as a function of the ratio.

According to another particular characteristic, the cartography is two-dimensional and reproduces an increasing curve.

According to yet another particular characteristic, the power threshold varies between a maximum power corresponding to totally electric propulsion and a minimum power corresponding to totally thermal propulsion.

According to yet another particular characteristic, the power threshold is determined equal to the maximum power when the ratio has a value at least equal to one and the power threshold is determined equal to the minimum power when the ratio has a zero value.

According to yet another particular characteristic, the electrical energy available is estimated as a function of first input data which is updated at a predetermined frequency and comprises an effective level of charge of a traction battery pack of the vehicle, a level of minimum load of the traction battery pack and an electrical consumption of ancillary units which is provided by the traction battery pack.

According to yet another particular characteristic, the electrical energy requirement for propulsion is estimated as a function of second input data provided at least partially by the navigation system which are updated at the predetermined frequency and include a remaining duration of the journey, a distance remaining to be traveled and a breakdown of the distance remaining to be traveled into sections belonging to different speed classes.

The invention also relates to a computer comprising a memory storing program instructions for implementing the method as briefly described above. According to a particular embodiment, the computer is a hybrid supervisor computer intended for the control of a traction chain with thermal/electric propulsion of a hybrid vehicle. The invention also relates to a rechargeable hybrid vehicle comprising a traction chain with thermal/electric propulsion and a computer as indicated above.

Other advantages and characteristics of the present invention will appear more clearly on reading the detailed description below of several particular embodiments of the invention, with reference to the appended drawings, in which:

Fig.1 is a basic block diagram relating to the implementation of the method according to the invention in a plug-in hybrid vehicle.

Fig.2 shows a curve relating to the energy management of the method according to the invention.

With reference to Fig.1, in the particular embodiment described here, the method according to the invention is implemented in a hybrid supervisor computer SH, also called "hybrid supervisor", of the traction chain CTH of a plug-in hybrid vehicle. The hybrid supervisor computer SH manages the operation of the traction chain CTH according to a thermal propulsion mode, an electric propulsion mode or a mixed thermal/electric propulsion mode.

As shown schematically in Fig.1, the traction chain CTH essentially comprises two driving machines, in the form of a heat engine MT and a rotating electric traction machine MEL, a mechanical transmission system ST and power trains. RO wheels.

The activation and operation of the thermal engine MT for the supply of an engine torque are controlled by the hybrid supervisor computer SH typically via an engine control computer (not shown). The engine control computer sets the operating parameters of the internal combustion engine in order to deliver power to the wheel, or torque to the wheel, requested by the hybrid supervisor computer SH. The electric machine MEL is controlled by the hybrid supervisor computer SH via an electronic power converter (not shown). A rechargeable traction battery pack (not shown), typically of lithium-ion (Li-ion) or nickel-metal hydride (NiMH) technology, supplies the electrical energy necessary for the operation of the MEL electric machine. The ST mechanical transmission system includes conventional mechanical components, such as clutch, gearbox, speed reducer, transmission shaft and others, necessary for the transmission of engine torque from the MT and MEL prime movers to the RO wheel sets of the vehicle.

In general, the SH hybrid supervisor computer implements different energy management strategies for the CTH powertrain depending on the vehicle's life situations, so as to meet the torque demands at the driver's wheel, while optimizing the vehicle energy consumption.

As shown schematically in FIG. 1, the hybrid supervisor computer SH hosts in a memory MEM an on-board software module GEH, hereinafter referred to as energy management module, which implements the aforementioned energy management strategies of the traction chain CTH. As visible in Fig.1, functional blocks AT and CH are included in the energy management module GEH. The GEH energy management module also includes other functional blocks performing known functions for the implementation of energy management strategies for the CTH traction chain. These other functional blocks will not be described here because their description is outside the scope of the present invention and is not necessary for the understanding thereof by those skilled in the art.

The AT functional block is a software sub-module of the energy management module GEH which is dedicated to the implementation of the method according to the invention. The functional block AT authorizes the implementation of the method according to the invention by the execution of program code instructions by a processor (not shown) of the hybrid supervisor computer SH.

The function of the AT functional block is to control the activation of the heat engine MT during the execution of a planned route. The AT functional block receives input data Db and Dd, described below, and provides a power threshold Pztep beyond which the heat engine MT must be activated. The AT functional block determines the power threshold Pztep so as to obtain optimum energy management of the traction chain CTH. More specifically, the heat engine MT is activated when a power, or torque, at the wheel Pdem, requested by the driver by pressing the accelerator pedal PA of the vehicle, becomes greater than the power threshold Pztep.

The functional block CH of the energy management module GEH ensures effective control of the heat engine MT and of the rotating electric traction machine MEL via control functions FAT and FAE, respectively.

The FAT function activates the heat engine MT when the power at the wheel Pdem requested by the driver becomes greater than the power threshold Pztep determined by the functional block AT. When the heat engine MT must be activated, the FAT function transmits a start command DEM to the engine control computer (not shown) of the heat engine MT. A torque setpoint at the wheel CT, calculated in particular from the power at the wheel Pdem requested by the driver, is also transmitted by the FAT function to the engine control computer.

The FAE function controls the MEL electric machine. When the electric propulsion must be activated by the energy management strategy, the FAE function transmits an ATE activation order to the electronic power converter (not shown) of the electric machine MEL. A torque setpoint at the wheel CE, calculated in particular from the power at the wheel Pdem requested by the driver, is also transmitted by the function FAE to the electronic power converter.

In the present invention, the AT functional block makes it possible to optimize the discharge of the traction battery pack during hybrid driving on a known route. When the driver indicates his destination to the vehicle's NAV navigation system, the journey can be made as economical as possible by using electric driving as much as possible and thermal driving as low as possible, while maintaining electric driving at low speed.

The method of the invention introduces a regulation of a ratio Ke=Ed/Eb, between an available electrical energy Ed and a need for electrical energy Eb, in order to correct in real time a discrepancy between a planned electrical consumption on the route and actual power consumption. It is thus possible to respect an optimal planning of the discharge of the traction battery block seeking to have electrical energy available throughout the journey, but without any remaining in the traction battery block once the journey has been completed.

In accordance with the invention, the regulation of the Ke=Ed/Eb ratio is obtained by means of an action on the power threshold Pztep which acts on the available electrical energy Ed. An increase in the power threshold Pztep leads to a heat engine MT which is used less often and therefore has greater consumption of available electrical energy Ed and a reduction in the ratio Ke. A reduction in the power threshold Pztep leads to a heat engine MT which is more often used and therefore to a lower consumption of available electrical energy Ed and an increase in the ratio Ke.

It will be noted that the power threshold Pztep corresponds to the "TEP zone power" known to those skilled in the art, expressed in Watts. In the state of the art, distinct zone powers having fixed values are assigned for the activation of the heat engine to sections of route to which different rolling speeds correspond. In the present invention, the value of the power threshold Pztep will also depend on the route sections with different rolling speeds, but this value will be adjusted by the regulation loop to regulate the Ke ratio.

As seen in Fig.1, the AT functional block essentially comprises a first FEB estimation function, a second FED estimation function, an FCR ratio calculation function and a FDS power threshold determination function.

The FEB estimation function is similar to the aforementioned prior art “GEPC” function. The study of the usual rolling cycles shows that the energy requirement per kilometer can be estimated approximately on the flat according to the average rolling speed of the vehicle over a course. The average driving speed is calculated from the distance traveled and the time elapsed. It is thus possible to determine an affine trend making it possible to calibrate the need for electrical energy as a function of the average driving speed of the section of route.

The FEB estimation function estimates the electrical energy requirement Eb from the aforementioned input data Db. The Db data are essentially provided by the vehicle's NAV navigation system which is based on a constellation of satellites such as “GPS®”, “GALILEO®”, “GLONAS®” or others. The data Db include in particular a remaining duration of the journey, a distance remaining to be traveled, as well as a distribution of this distance remaining to be traveled into sections belonging to different speed classes. The Db input data is updated at a determined frequency.

Thus, for example, the different speed classes may include a class A for a speed interval between 0 and 30 km/h, a class B for a speed interval between 30 and 50 km/h, a class C for an interval of speed between 50 and 70 km/h, a class D for a speed interval between 70 and 100 km/h and a class E for speeds above 100 km/h. The information provided to the FEB function will typically take the form of a percentage of the distance traveled in each class.

The FED estimation function estimates the electrical energy Ed available in the traction battery pack for the electric propulsion of the vehicle from the aforementioned Dd data. The charge level of the traction battery pack, charge level called "SOC" for "State of Charge", makes it possible to calculate the useful electrical energy which is contained in it. The electrical energy Ed available for the electrical propulsion of the vehicle is obtained by withdrawing from the useful electrical energy contained in the traction battery pack the electrical energy necessary for supplying auxiliary components of the vehicle over the duration of the journey . The SOC state of charge of the traction battery pack and electrical consumption data are typically provided directly by a battery management system called "BMS", for "Battery Management System" in English, or calculated from information provided by this system.

The input data Dd necessary for the FED function to calculate the available electrical energy Ed are generally already present in the hybrid supervisor calculator SH, because they are used by other strategies. The input data Dd are updated at the aforementioned determined frequency and include in particular the effective level of charge SOC of the traction battery pack expressed as a percentage of the total capacity of the latter, the maximum capacity of the traction battery pack allowing to obtain electrical energy from the effective charge level SOC, a minimum charge level SOCmin, called "target", which is regulated when the charge level of the traction battery pack becomes low and an electrical consumption of organs auxiliaries supplied by the traction battery pack. The minimum charge level SOCmin is the zero level of the useful electrical energy of the traction battery pack. The supply of electrical power to auxiliary components is a priority for the operation of the vehicle and the corresponding electrical energy is therefore not available for electric propulsion.

The FCR ratio calculation function calculates the Ke = Ed/Eb ratio between the available electrical energy Ed and the electrical energy requirement Eb.

The ratio Ke is supplied as input to the power threshold determination function FDS. The FDS power threshold determination function determines the power threshold Pztep = f(Ke) using a two-dimensional (2D) map. This mapping typically reproduces an increasing 2D curve.

The power threshold Pztep is calculated in real time and is typically provided at the same frequency as the determined frequency at which the input data Db and Dd are updated.

With reference also to FIG. 2, the power threshold Pztep is calibrated between two powers Pmax and Pmin.

The power Pmax is the maximum value of Pztep. The power Pmax results in maximum electrical expenditure for propulsion in the traction battery pack. In part A of the curve shown in Fig.1, Pztep = Pmax and the mode of propulsion is then totally electric. In this mode of operation, the Ke ratio is at least equal to one, with an available electrical energy Ed which covers the electrical energy requirement Eb.

Power Pmin is the minimum value of Pztep. Power Pmin does not cause any electrical expenditure for propulsion in the traction battery pack. The traction battery pack is then in its minimum state of charge SOCmin. In part B of the curve shown in Fig.1, Pztep = Pmin and the mode of propulsion is totally thermal. The SOC state of charge of the traction battery pack is then regulated to its minimum state of charge SOCmin. In this mode of operation, the ratio Ke is equal to zero, with an available electrical energy Ed which is zero.

As shown schematically by the arrow FA in Fig.2, when the Ke ratio decreases, this causes a decrease in the power threshold Pztep which reduces the electrical expenditure for propulsion in the traction battery pack by increased stress on the heat engine MT. An increase in the Ke ratio will therefore follow. As shown schematically by the arrow FB in Fig.2, when the Ke ratio increases, this causes an increase in the power threshold Pztep which increases the electrical expenditure for propulsion in the traction battery pack by less stress on the heat engine MT. A decrease in the Ke ratio will therefore follow.

The regulation loop introduced in the present invention makes it possible to stabilize the value of the Ke ratio. This allows the energies Ed and Eb to vary together without diverging and guarantees, at the end of the journey, convergence of the SOC charge level of the traction battery pack towards its minimum charge level SOCmin, and this in a robust manner with respect to the errors in estimating the electrical expenditure and, to a certain extent, the slope.

The method according to the invention provides the guarantee that the energy available in the traction battery pack will be spent over the exact distance of the route, which is a necessary condition for optimizing fuel consumption on the route. All of the cheapest energy, i.e. the electrical energy available in the traction battery pack, will have been consumed while retaining the possibility, if necessary, of finishing the journey by electric driving, for example, in the case of an arrival in an urban area with controlled traffic in which electric driving is imposed.

The invention thus provides an economic advantage for the vehicle owner, with lower fuel consumption, and is of certain interest for the objectives of sustainable development. Furthermore, the method of the invention being implemented by software, without any added hardware device, the cost of its integration into a vehicle is very low.

The invention is not limited to the particular embodiments which have been described here by way of example. The person skilled in the art, depending on the applications of the invention, may make various modifications and variants falling within the scope of protection of the invention.

Claims (10)

Method for energy management on a known route of a traction chain with thermal/electric propulsion (CTH) in a hybrid vehicle, said method comprising planning a run of said hybrid vehicle on said known route from data provided by a navigation system (NAV) of said vehicle and an activation of a heat engine of said hybrid vehicle for propulsion thereof when a power at the wheel requested (Pdem) becomes greater than a power threshold (Pztep), characterized in that it comprises a regulation of a ratio (Ke) between an available electrical energy (Ed) and an electrical energy requirement (Eb) for said propulsion, said power threshold (Pztep) being determined as a function of said ratio (Ke ) so as to obtain said regulation. Method according to Claim 1, characterized in that the said power threshold is determined using a map (FDS) as a function of the said ratio (Ke, E_K). Method according to Claim 2, characterized in that the said cartography (FDS) is two-dimensional and reproduces an increasing curve. Method according to any one of Claims 1 to 3, characterized in that the said power threshold (Pztep) varies between a maximum power (Pmax) corresponding to totally electric propulsion and a minimum power (Pmin) corresponding to totally thermal propulsion. . Method according to Claim 4, characterized in that the said power threshold (Pztep) is determined equal to the said maximum power (Pmax) when the said ratio (Ke) has a value at least equal to one and the said power threshold (Pztep) is determined equal to said minimum power (Pmin) when said ratio (Ke) has a zero value. Method according to any one of Claims 1 to 5, characterized in that the said available electrical energy (Ed) is estimated according to first input data (Dd) which are updated at a predetermined frequency and include an effective charge level of a traction battery pack of said vehicle, a minimum charge level of said traction battery pack and an electrical consumption of auxiliary devices which is supplied by said traction battery pack. Method according to Claim 6, characterized in that the said electrical energy requirement (Eb) for the said propulsion is estimated as a function of second input data (Db) supplied at least partially by the said navigation system (NAV) which are updated at said predetermined frequency and include a remaining duration of the journey, a distance remaining to be covered and a distribution of said distance remaining to be covered into sections belonging to different speed classes. Computer (SH) comprising a memory (MEM) storing program instructions for implementing the method according to any one of Claims 1 to 7. Computer according to Claim 8, characterized in that the said computer is a hybrid supervising computer (SH) intended for controlling a traction chain with thermal/electric propulsion (CTH) of a hybrid vehicle. Plug-in type hybrid vehicle comprising a traction chain with thermal/electric propulsion (CTH), characterized in that it comprises a computer (SH) according to claim 9.