FR3141392A1 - Method for implementing a particular phase of operation of the thermal engine of a hybrid vehicle - Google Patents

Abstract

The present invention relates to a method of implementing a particular phase of operation of a thermal engine of a hybrid vehicle comprising an electric machine powered by a battery. It includes the following steps: the need to initiate a particular operating phase and the duration of said phase are assessed; the mechanical power capable of being produced by said thermal engine is evaluated; the future course of the motor vehicle is determined; the mechanical power necessary to ensure said stroke is evaluated and the difference in mechanical power with said mechanical power capable of being produced by said thermal engine is calculated; the electrical power necessary for the operation of said electrical machine is calculated as a function of said difference in mechanical power; and said particular operating phase of said heat engine is triggered as a function of said electrical power necessary for the operation of said electrical machine and of the electrical energy stored in said accumulator battery. Figure to be published with the abstract: Fig. 2

Description

Method for implementing a particular phase of operation of the thermal engine of a hybrid vehicle

The present invention relates to a method of controlling a hybrid automobile vehicle comprising a heat engine and an electric machine.

More particularly, the present invention relates to a method for conditionally implementing a particular phase of operation of the thermal engine of the hybrid vehicle.

Known hybrid vehicles include a thermal engine and at least one electric machine. The heat engine is powered by a combustible hydrocarbon, while the electric machine is powered by a storage battery.

We can refer to the publication FR-A1-3022495 which describes such a motor system and an associated control method. In one of the embodiments disclosed by this publication, the heat engine is associated with a first electric machine, which can be described as main, and which is capable of driving the vehicle alone or in combination with the heat engine, and in addition to a second electric machine, which can be described as secondary, which only allows a battery of accumulators to be recharged when it is driven by the thermal engine, but which cannot participate in driving the vehicle. Other hybrid engine systems are possible, in particular systems comprising several electric machines, for example two, which are capable of driving the vehicle.

The heat engine has, at the exhaust gas outlet, a catalyst allowing in particular the reduction of nitrogen oxides produced during the combustion reaction. However, this catalyst must be raised above a temperature threshold to be effective, that is to say, for the rate of reduction of nitrogen oxides to be sufficiently high.

Therefore, the coupling of the heat engine and the electrical machine(s) must be adjusted so that the heat engine operates according to particular operating phases allowing the catalyst to maintain its temperature.

On the other hand, there are particular phases of operation of the heat engine that are more restrictive, for example when it comes to regenerating a particle filter. This particular phase of operation is then carried out when the mass of fine particles stored inside the filter reaches a predefined threshold.

When the heat engine is a spark ignition engine, for example gasoline, it requires mechanically driving the heat engine through the electric machine, while the fuel injection is cut off, so as to be able to power the filter particles in the air and therefore in oxygen. The heat engine then plays the role of an air pump, which helps to promote the combustion of the fine particles stored in the filter.

Such a particular operating phase necessarily penalizes the driving conditions of the vehicle, because it requires the electric machine which must, by itself, both ensure the movement of the vehicle and, moreover, the drive of the thermal engine. Therefore, it is necessary to ensure, before ordering the regeneration of the particle filter, that the accumulator battery is sufficiently charged.

On the other hand, if the motor vehicle begins an upward stroke, such a particular operating phase may not be able to complete due to lack of a sufficient quantity of energy to be able to drive the vehicle.

Also, a problem which arises and which the present invention aims to resolve is to provide a method of controlling a hybrid motor vehicle making it possible to begin a particular phase of operation of the thermal engine without seeing it interrupted unintentionally.

With the aim of solving this problem, and according to a first object, a method is proposed for conditionally implementing a particular phase of operation of a thermal engine of a powertrain of a hybrid motor vehicle, said powertrain comprising in addition an electric machine powered by a battery of accumulators capable of storing electrical energy. The method according to the invention comprises the following steps: the need to initiate a particular operating phase of said heat engine and the duration of said phase are evaluated; the mechanical power capable of being produced by said thermal engine during said particular phase of operation is evaluated; the future travel of the motor vehicle is determined during a period corresponding to said duration of said particular operating phase; we evaluate the mechanical power necessary for the powertrain to ensure said future stroke during said period and we calculate the difference in mechanical power with said mechanical power capable of being produced by said thermal engine; the electrical power necessary for the operation of said electrical machine during said period is calculated as a function of said difference in mechanical power; and said particular operating phase of said heat engine is triggered as a function of said calculated electrical power necessary for the operation of said electrical machine and of the electrical energy stored in said accumulator battery.

Thus, a characteristic of the invention lies in taking into account the future travel of the motor vehicle during a time interval corresponding to the duration of the particular operating phase required by the thermal engine, in order to be able to trigger this operating phase . This future course is determined, for example, by a GPS device programmed by the driver of the vehicle. And it makes it possible to define a temporal projection of the powers required by the powertrain.

In other words, by taking this future race into account, it is established whether the particular phase of operation of the vehicle's thermal engine can be started taking into account the resources of the accumulator battery. It is in fact the electric motor which will have to supplement, at least partially, the thermal engine which is temporarily prevented during this particular phase of operation.

Thus, said particular operating phase of said heat engine is preferably triggered if, in addition, said electrical energy stored in said accumulator battery is greater than a minimum authorization threshold. Indeed, if the accumulator battery is completely discharged, the particular operating phase cannot be started in any case.

Also, according to a particularly advantageous implementation characteristic of the invention, the electrical energy stored in said accumulator battery is further evaluated at the end of said period in order to be able to trigger said particular operating phase of said thermal engine. More precisely, we evaluate the electrical energy which will in all likelihood be stored in the accumulator battery at the end of the particular operating phase of the thermal engine. This is obviously made possible thanks to the determination of the future race during the period corresponding to this phase.

Advantageously, said particular operating phase of said heat engine is triggered if, in addition, said electrical energy stored in said accumulator battery at the end of said period is greater than a deactivation threshold. In this way, we eliminate the need for a fully discharged accumulator battery as soon as the particular operating phase ends.

According to a particularly advantageous embodiment of the invention, the method further comprises the following steps: the limit mechanical power capable of being produced by said electrical machine is provided; we further calculate the total duration during which the mechanical power supplied by said electrical machine is less than said difference in mechanical power; and, said particular operating phase of said heat engine is triggered if in addition said total duration is less than a duration threshold.

Indeed, the charge of the accumulator battery at the moment when we decide to start the particular operating phase of the thermal engine is important to know. However, it is possible that, despite a significant load, the future driving conditions of the vehicle are so severe that the capacities of the electric machine, even with a charged accumulator battery, do not allow the particular operating phase to be carried out. Consequently, we evaluate the total duration during which this impossibility appears and we can tolerate the implementation of the particular phase of operation if this total duration is low and less than the predefined duration threshold.

Furthermore, the torque authorized by the heat engine and the speed authorized by said heat engine during said particular operating phase are provided in order to be able to evaluate said mechanical power capable of being produced by said heat engine. The calculations to evaluate the mechanical power of the heat engine capable of being produced will be detailed in the remainder of the description.

According to a particularly advantageous mode of implementation, the respectively minimum and maximum torques authorized by the heat engine and the respectively minimum and maximum speeds authorized by said heat engine during said particular operating phase are provided in order to be able to evaluate the minimum mechanical power and the maximum mechanical power capable of being produced by said thermal engine.

Therefore, we calculate the difference in mechanical power with said minimum mechanical power capable of being produced by said thermal engine, on the one hand, and the difference in mechanical power with said maximum mechanical power capable of being produced by said thermal engine, d 'somewhere else.

According to a variant of execution, said particular operating phase of said heat engine is triggered, as a function of said calculated electrical power necessary for the operation of said electrical machine and of the electrical energy stored in said accumulator battery, or, if the need to initiate a particular operating phase of said heat engine has been required for a duration greater than another duration threshold.

Indeed, there are situations where the particular operating phase of the heat engine is imperative at the risk of compromising the proper operation of the heat engine. Therefore, it is necessary to begin this phase whatever happens and even if we cannot bring it to its conclusion.

According to another object, a hybrid motor vehicle is proposed comprising, on the one hand a thermal engine and an electric machine powered by a battery of accumulators capable of storing electrical energy and on the other hand, an on-board computer suitable for implementing the method as described above.

Other particularities and advantages of the invention will emerge on reading the description given below of a particular embodiment of the invention, given for information but not limitation, with reference to the appended drawings in which:

is a flowchart showing the first steps of the method according to the invention; And,

is a flowchart showing other steps of the method according to the invention.

The method according to the invention applies to a hybrid automobile vehicle comprising a thermal engine and at least one electric machine. The thermal engine is powered by conventional fuel, while the electric machine is powered by one or more rechargeable storage batteries.

The heat engine requires specific operating conditions when it comes, for example, to activate the heating of a catalyst or the regeneration of its particle filter, or even to carry out self-diagnostics.

Also, to command and monitor these particular operating conditions, the vehicle is equipped with an on-board computer including a diagnostic interface allowing hardware diagnosis of the thermal engine and the main equipment of the vehicle to be carried out.

Consequently, the on-board computer includes a program making it possible to control the vehicle in accordance with the invention, whenever a particular phase of operation of the vehicle is required.

Thus, when the mass of fine particles stored in the filter reaches a predetermined threshold, for example, it is necessary to regenerate the particle filter. From then on, the fuel injection is stopped, and the electric machine takes over to drive both the motor vehicle and the thermal engine. The latter then functions as a pump to supply air and therefore oxygen to the combustion of fine particles.

Under these conditions, we understand that the accumulator battery must be sufficiently charged to be able to power the electrical machine, which must produce significant mechanical power.

When self-diagnostics of the heat engine must be carried out, for some of them, the heat engine remains in operation. Consequently, it can contribute to the propulsion of the motor vehicle, to a certain extent, in addition to the electric machine. This mode of operation is called “parallel hybrid”.

We then understand that the implementation of these particular operating conditions requires more or less stress on the electrical machine, and consequently, on the storage battery.

However, in certain driving conditions, the powertrain, including the combustion engine and the electric machine, is under heavy strain, for example when the vehicle begins climbing a pass. Also, for example, a regeneration of the particle filter, started before the rise of the pass, risks being interrupted before its completion, if the accumulator battery is not sufficiently charged to drive both the vehicle and the engine thermal during the ascent.

Thanks to the method according to the invention, the future driving conditions of the motor vehicle are anticipated in order to be able to decide whether or not to initiate one or the other of the particular operating conditions.

These future driving conditions, in other words, the temporal projection of the powers required by the powertrain, are developed from a pre-programmed GPS route or are determined by a driving assistance system according to the ADASIS protocol for example, which will make it possible to select a path from a plurality of possible paths, for example the path which will result in the highest required power.

The method then operates in three successive stages. First of all, in a first step we proceed to calculate the minimum and maximum mechanical powers capable of being produced by the heat engine during the particular operating phase.

Then, in a second step according to an iterative process, the energy level contained in the accumulator battery is estimated at the end of the particular operating phase, and also, the duration during which the constraints emitted by the thermal engine do not would not be respected at the end of the particular phase if it were activated at a given time t .

And finally, in a third step, depending on the current energy contained in the accumulator battery and the energy estimated at the end of the particular phase requested by the thermal engine or the duration during which the constraints emitted by the heat engine would not be respected, we decide whether or not to accept the request for the particular operating phase requested by the heat engine.

Thus, as soon as a particular phase of operation of the heat engine is required, the first step of the method, illustrated on the flowchart of the , consists of calculating the maximum and minimum mechanical powers that can be produced by the heat engine during the particular operating phase. To do this, in a first recording sub-step 10 of the first step, torque values and rotation speed values authorized by the heat engine are recorded during the particular operating phase called to be implemented.

We therefore record the maximum authorized torque value CPLmax and the minimum authorized torque value CPLmin on the one hand, and the maximum authorized rotation speed VRmax and the minimum authorized rotation speed VRmin on the other hand.

Then, according to a second comparison sub-step 12 of the first step, if the maximum torque CPLmax and the minimum torque CPLmin are both positive or zero, we calculate in a third power calculation sub-step 14 of the first step, the minimum mechanical power PMCmin as being the product of the minimum torque CPLmin and the minimum rotation speed VRmin multiplied by π/30 and the maximum mechanical power PMCmax as being the product of the maximum torque CPLmax and the maximum rotation speed VRmax multiplied by π/30.

If, on the other hand, the maximum torque CPLmax and the minimum torque CPLmin are both negative, in accordance with a fourth comparison sub-step 16 of the first step, we then calculate in a fifth power calculation sub-step 18 of the first step , the minimum mechanical power PMCmin as being the product of the minimum torque CPLmin and the maximum rotation speed VRmax multiplied by π/30 and the maximum mechanical power PMCmax as being the product of the maximum torque CPLmax and the minimum rotation speed VRmin multiplied by π/30.

But, if the maximum torque CPLmax and the minimum torque CPLmin have opposite signs, we then calculate in a sixth power calculation sub-step 20 of the first step, the minimum mechanical power PMCmin as being the product of the minimum torque CPLmin and the maximum rotational speed VRmax multiplied by π/30 and the maximum mechanical power PMCmax as being the product of the maximum torque CPLmax and the maximum rotational speed VRmax multiplied by π/30.

When the first step shown on the is completed, we then know the maximum mechanical powers PMCmax and minimum PMCmin authorized by the heat engine during the particular phase of operation and these values will then be used in the second step consisting of both estimating the energy contained in the battery accumulators at the end of the duration of the particular operating phase as well as to establish the potential duration during which the minimum and maximum powers authorized by the thermal engine cannot be respected.

First of all, this second step, called iterative step, works in a loop. It is illustrated schematically on the flowchart shown on the , delimited by a broken line 21.

The implementation of this second step requires feeding the loop, not only with the maximum mechanical powers PMCmax and minimum PMCmin, calculated during the first step, but also, with the temporal projection of the PTPW powers required for the powertrain, developed for example from a GPS route pre-programmed by the driver, and moreover with the duration necessary to carry out the particular DPPF operating phase, which DPPF duration is estimated and transmitted by the thermal engine according to its own needs .

The number of iterations of the NbBCL loop is then the quotient of the duration necessary to carry out the particular DPPF operating phase and a temporal recurrence X of the entry authorization strategy in the particular operating phase.

Thus, for each iteration until reaching the number NbBCL, in addition to the maximum mechanical powers PMCmax and minimum PMCmin authorized by the heat engine during the particular phase of operation and provided in the first step, we also provide the corresponding value PTPW of the projection time of the powers PTPW(t).

Then, according to a first calculation sub-step 26 of the second step, we calculate on the one hand the minimum power PElecMin that the electric machine, or where appropriate, the plurality of electric machines, must provide, as being the difference between the power maximum mechanical power authorized by the thermal engine PMCmax and the power required from the powertrain, in other words the PTPW value of the temporal projection of the powers, and we calculate on the other hand the maximum power that the electric machines PElecMax will have to provide as being the difference between the minimum mechanical power authorized by the thermal engine PMCmin and the power required for the PTPW powertrain.

According to a second calculation sub-step 28 of the second step, thanks to the maximum powers PElecMax and minimum PElecMin, we calculate the total duration TLPMinMax where the heat engine does not see its minimum and maximum power limits respected.

If the minimum power that the PElecMin electric machine must provide is greater than a maximum mechanical power achievable by the PMElecMax electric machine and supplied in the second stage, or if the maximum power that the PElecMax electric machine must provide is less than one minimum mechanical power achievable by the electric machine PMElecMax, then this implies that the electric machine cannot produce the power allowing it to respect the minimum and maximum powers authorized by the thermal engine PMCmin, PMCmax and the will of the driver, i.e. the corresponding value PTPW of the temporal projection of powers. The driver's desire corresponds to the desire to accelerate, which is translated into a power or torque setpoint at the wheel for driving the vehicle.

Also, under these conditions, the time counter previously initiated at "0", is then incremented by the temporal recurrence of strategy X compared to its previous value in the loop.

It will be observed that the maximum mechanical power achievable by the PMElecMax electric machine includes the mechanical limit of the latter and the discharge power limits of the storage batteries. Also, the minimum mechanical power achievable by the PElecMin electric machine includes the mechanical limit of the latter and the charging power limits of the storage battery.

According to a third sub-step 30 of the second step, the electrical power to be consumed or produced PElecReq by the electrical machine is calculated as a function of the energy difference between a nominal target energy of the vehicle ENC and the energy estimated at each step of time of the EEst loop which will be calculated below. The difference between these two ENC energies, EEst, is entered into a configurable table which then makes it possible to define the estimated optimal electrical power level for charge/discharge.

According to a fourth sub-step 32 of the second step, the electrical power consumed or produced by the electrical machine PElec is calculated as a function of the mechanical power limits, PElecMax, PElecMin, which the electrical machine must provide, and the electrical power to be consumed or to produce PElecReq by the electric machine.

Initially, the mechanical power limits PElecMax, PElecMin achievable by the electric machine, are limited respectively to the maximum mechanical powers PMElecMax and minimum PMElecMin achievable by the electric machine, i.e. to the maximum and minimum mechanical powers of the electric machine making it possible to comply with the corresponding value PTPW of the temporal projection of the powers and the maximum and minimum powers authorized by the thermal engine PMCmax, PMCmin, consolidated with the physical limits of the electric machine.

• MIN [ PMElecMax ; MAX (PElecMax ; PMElecMin)] ;
• MIN [ PMElecMax ; MAX ( PElecMin ; PMElecMin)].

These consolidated mechanical powers are denoted respectively PMElecCsMax and PMElecCsMin and they are worth respectively:

• MIN [SMElecMax; MAX (PElecMax; PMElecMin)];
• MIN [SMElecMax; MAX (PElecMin; PMElecMin)].

• PElecWMax = PMElecCsMax + FPP(PMElecCsMax)² ;
• PElecWMin = PMElecCsMin + FPP(PMElecCsMin)² ;

dans lesquelles le coefficient FPP de second ordre et paramétrable est un facteur de perte de puissance de la machine électrique et de la batterie. La valeur de ce coefficient est fonction du signe de la puissance mécanique considérée.Secondly, these mechanical powers of the electrical machine PMElecCsMax and PMElecCsMin are respectively converted into maximum and minimum electrical powers PElecWMax and PElecWMin via the equations below:

• PElecWMax = PMElecCsMax + FPP(PMElecCsMax)²;
• PElecWMin = PMElecCsMin + FPP(PMElecCsMin)²;

in which the second-order and configurable FPP coefficient is a power loss factor of the electric machine and the battery. The value of this coefficient depends on the sign of the mechanical power considered.

Thirdly, we consolidate the electrical power to be consumed or produced PElecReq by the electrical machine by means of the power field authorized and calculated above: PElecWMax and PElecWMin.

This then results in the estimated final electrical power PElec, produced by the electrical machine on the current iteration in the loop.

Finally, with this estimated final electrical power PElec, we integrate, according to a fifth integration sub-step 34 of the second step, the estimated energy value EEst at each iteration of the loop from the estimated energy of the previous iteration and also from the estimated final electrical power PElec factor of the aforementioned temporal recurrence

To initialize this second iterative step, the estimated energy value for the first iteration is the value of the current energy in the accumulator battery: ENCrt.

When the maximum number of iterations of the NbBCL loop is reached, then EEst represents the estimated energy at the end of the particular phase of operation requested by the heat engine, while TLPMinMax represents the total duration during which the particular phase of operation of the engine thermal engine does not make it possible to respect the minimum and maximum torques and speeds required by the thermal engine, CPLmax, CPLmin and VRmax, VRmin.

Thus, in a third determination step 36 and last step, it is determined whether the particular phase of operation of the heat engine required can be authorized, and this, not only based on the energy estimated at the end of the particular phase of operation requested by the heat engine EEst and the total duration during which the particular phase of operation of the heat engine does not make it possible to respect the minimum and maximum torques and speeds TLPMinMax, thanks to the second stage, but also in accordance with predefined values of minimum threshold of authorization SMinAuto, deactivation threshold SDesact and adjustable duration threshold STempR.

Thus, this phase is authorized to the extent that the heat engine requires a particular operating phase and if the current energy in the ENCrt accumulator battery is greater than a predefined minimum authorization threshold SMinAuto, on the one hand; and in addition, if the estimated energy value EEst is greater than a deactivation threshold SDisact also predefined, and that the total duration TLPMinMax during which the particular phase of operation of the thermal engine does not make it possible to respect the minimum torques and speeds and maximum required is less than an adjustable duration threshold STempR; or if the particular operating phase of the heat engine is required for a duration greater than a configurable threshold.

On the other hand, the particular operating phase of the thermal engine is not authorized, if obviously it is not required or if the current energy in the accumulator battery ENCrt is lower than the deactivation threshold SDesact.

Claims (10)

Method for conditionally implementing a particular phase of operation of a thermal engine of a powertrain of a hybrid motor vehicle, said powertrain further comprising an electric machine powered by a battery of accumulators capable of storing energy electrical energy, characterized in that it comprises the following stages:
- the need to initiate a particular operating phase of said heat engine and the duration of said phase are evaluated;
- the mechanical power capable of being produced by said thermal engine during said particular operating phase is evaluated;
- the future travel of the motor vehicle is determined during a period corresponding to said duration of said particular operating phase;
- we evaluate the mechanical power necessary for the powertrain to ensure said future stroke during said period and we calculate the difference in mechanical power with said mechanical power capable of being produced by said thermal engine;
- the electrical power necessary for the operation of said electrical machine during said period is calculated as a function of said difference in mechanical power;
and said particular operating phase of said heat engine is triggered as a function of said calculated electrical power necessary for the operation of said electrical machine and of the electrical energy stored in said accumulator battery. Method according to claim 1, characterized in that said particular operating phase of said thermal engine is triggered if in addition said electrical energy stored in said accumulator battery is greater than a minimum authorization threshold (SMinAuto). Method according to claim 1 or 2, characterized in that the electrical energy stored in said accumulator battery is further evaluated at the end of said period (EEst) in order to be able to trigger said particular operating phase of said thermal engine. Method according to claim 3, characterized in that said particular operating phase of said heat engine is triggered if, in addition, said electrical energy stored in said accumulator battery at the end of said period (EEst) is greater than a threshold of deactivation (SOff). Method according to any one of claims 1 to 4, characterized in that it further comprises the following steps:
- the limit mechanical power capable of being produced by said electrical machine is provided;
- we further calculate the total duration during which the mechanical power supplied by said electrical machine is less than said difference in mechanical power; And,
- said particular operating phase of said heat engine is triggered if in addition said total duration is less than a duration threshold (STempR). Method according to any one of claims 1 to 5, characterized in that the torque authorized by the heat engine and the speed authorized by said heat engine during said particular phase of operation are provided in order to be able to evaluate said mechanical power capable of being produced by said thermal engine. Method according to claim 6, characterized in that the respectively minimum and maximum torques authorized by the heat engine and the respectively minimum and maximum speeds authorized by said heat engine during said particular operating phase are provided in order to be able to evaluate the minimum mechanical power and the maximum mechanical power capable of being produced by said thermal engine. Method according to claim 7, characterized in that the difference in mechanical power with said minimum mechanical power capable of being produced by said heat engine, on the one hand, and the difference in mechanical power with said maximum mechanical power capable of being produced are calculated. to be produced by said thermal engine, on the other hand. Method according to any one of claims 1 to 6, characterized in that said particular operating phase of said heat engine is triggered, as a function of said calculated electrical power necessary for the operation of said electrical machine and of the electrical energy stored in said accumulator battery, or, if the need to initiate a particular operating phase of said thermal engine has been required for a duration greater than another duration threshold. Hybrid motor vehicle comprising, on the one hand a thermal engine and an electric machine powered by a battery of accumulators capable of storing electrical energy and on the other hand, an on-board computer adapted to implement the method according to any of claims 1 to 9.