FR2944768A1 - METHOD FOR SUPPLYING A HYBRID MOTOR PUSH GROUP - Google Patents

Abstract

The method has an internal source of irreversible energy and an internal source of reversible energy (1). The internal source of reversible energy is rechargeable by drawing directly or indirectly from the internal source of irreversible energy and by providing a finite amount of reversible energy from an external source. The method executes, at least until the finished quantity has been exhausted, a first function (a) which controls a power supply from the internal source of reversible energy (1) so as to ensure an intrinsic gain of positive value.

Description

Method for feeding a hybrid powertrain

The field of the invention is that of plug-in hybrid vehicles. A rechargeable hybrid vehicle has two separate energy reservoirs, one reversible constituted by an electrical storage unit, the other non-reversible constituted by a fuel tank. The energy of the fuel tank is converted into mechanical energy by a heat engine. The energy of the electrical storer is converted into mechanical energy by one or more electrical machines. The plug-in hybrid vehicle differs from a non-rechargeable hybrid vehicle by generally offering the possibility of recharging the electric storage in four ways. One way is to convert the kinetic energy of the vehicle which is a function of its speed into electrical energy through one or more electrical machines. A second way is to convert the potential energy of gravity of the vehicle which is a function of its altitude, into electrical energy through one or more electrical machines.

A third way is to convert the energy of the non-reversible tank that contains the fuel into electrical energy through the engine and one or more electrical machines. A fourth way is to transfer the energy of a terrestrial electric network of electricity type of the sector, to the electrical storer through for example a socket, a rectifier and a current transformer. The field of the invention is more particularly that of the energy management of the electrical storer.

The document FR2907745 discloses a method of energy management for a hybrid vehicle which consists in determining in real time, a gain in fuel consumption of the engine by the use of electric energy, so as to decide to turn on or off the thermal motor. In this method of the prior art, only the first three ways mentioned above, are used to recharge the electrical storage. The problem of optimizing the consumption gain by using the energy recharged in the storage device in the fourth way does not arise. EP1864849 discloses an energy control system for a fully electric vehicle. The problem of optimizing the consumption gain by selecting the energy to be used among a thermal energy of irreversible nature and the energy recharged in the storage of reversible nature does not arise. On the other hand the exploitation of the disclosed system is limited essentially to public transport vehicles with a determined and therefore predictable path. It seems difficult to achieve, see unrealizable to exploit the system disclosed in a vehicle with unpredictable course. The invention aims to establish an optimum use of a reversible energy, including an electrical from a distribution network in the case of use without time limit. The invention also aims to establish a consumption gain produced by a reversible energy input, including electrical energy in the case of use without time limit. The invention also aims to establish, in the case of a limited use in time that does not allow the integral use of the reversible energy supply, including electrical, recharged according to the optimal strategy, a new use of said electrical energy in order to achieve full and optimal use of this energy. The objectives are achieved by means of the invention, which relates to a method for feeding a hybrid powertrain from an internal source of irreversible energy and an internal source of reversible energy that is rechargeable by drawing on directly or indirectly in the internal source of irreversible energy and by providing a finite amount of reversible energy from an external source. The method is remarkable in that it performs, at least until exhausting of said finite quantity provided, a first function which controls a supply from the internal source of reversible energy so as to ensure an intrinsic gain of positive value . In particular, at a time of operation of the powertrain, the intrinsic gain is equal to the difference between a first quantity consumed by supplying the entire powertrain from the internal source of irreversible energy at said instant and a second quantity consumed at a given moment. subsequent instant by drawing directly or indirectly into the internal source of irreversible energy to recharge the internal source of reversible energy when it is used to power the entire powertrain at the instant. Advantageously, the method executes, at least until exhausting of said finite quantity provided, a second function which controls a supply from the internal source of reversible energy so as not to draw directly into the internal source of irreversible energy. to recharge the internal source of reversible energy. Advantageously also, the process executes, at least until the said finished quantity has been added, a third function which controls a supply from the internal source of reversible energy so as to rapidly exhaust the said finite quantity supplied. Advantageously, the method executes, at least until exhausting of said finite quantity provided, a fourth function which controls a power supply from the internal source of reversible energy so as to minimize the power supply from the source. internal irreversible energy. More particularly, the internal source of reversible energy is of an electrical nature. The invention also relates to a power supply system of a hybrid powertrain from an internal source of irreversible energy and an internal source of reversible energy that is rechargeable by drawing directly or indirectly in the source internal energy irreversible and by providing a finite amount of reversible energy from an external source. The system is remarkable in that it is arranged to implement the method according to the invention. The invention further relates to a vehicle, particularly a motor vehicle which comprises a system according to the invention. The invention will be better understood, and other objects, features, details and advantages thereof will appear more clearly in the following explanatory description referring to the drawings given solely by way of example to illustrate an embodiment of the invention. the invention and in which: - Figure 1 is a schematic view of energy flows in a hybrid vehicle without reloading; FIG. 2 gives torque versus velocity curves delineating positive gain and negative gain areas; FIG. 3 is a schematic view of comparison of energy flows in a hybrid vehicle without refueling and in a hybrid vehicle with refueling; FIG. 4 gives curves comparable to that of FIG. 2 when the electric machine is more involved in motor mode; - Figure 5 is a schematic view similar to that of Figure 3 when implementing a load shedding energy; Figure 6 is a schematic diagram of various possible strategies for saving fuel; FIG. 7 is a comparison diagram of the strategies of FIG. 6. Three phases are defined in the use of the rechargeable hybrid vehicle. The first phase is the charging phase of the vehicle on the network. The vehicle is supposed to stop. During the second phase, the energy thus recharged can be used according to strategies specific to the rechargeable hybrid vehicle. The third phase occurs when all the recharged energy has been consumed. The vehicle then uses strategies identical to those of a non-rechargeable hybrid vehicle. The invention is concerned with the management of the energy of the electrical storer during the second phase. The strategies used during the third phase are not specifically the subject of this invention. During the second phase, it is sought to determine when the heat engine must be switched off, the machine or machines participating alone in the traction of the vehicle. On the other hand, when the heat engine is turned on, it is established how to use the energy of the electric storage unit. These choices are guided by the search for a minimum fuel consumption on a given route.

Figure 1 shows the energy balance of a full non-rechargeable hybrid vehicle (FHnR for non-rechargeable Full Hybrid). It is noted that the electrical storer 1 is the point of a power distribution network through which all the energies related to the hybridization transit. A decomposition of the energy flows at the level of the electric storage unit for a vehicle FHnR takes into account a water energy consumed by the auxiliaries including for example the on-board network 2, an Erecup energy recovered in deceleration from the wheels 3 of the vehicle, an energy Er mth recharged by the heat engine, Etep energy consumed for electric driving, in particular by an electric machine 5 15 when operating in engine mode, Edel energy consumed for the unloading of the heat engine and an energy Epert which represents the losses of electrical storage. The equation of the balance sheet is as follows: 20 Waters - Erecup ù Er_mth + Etep + Edel + Epert = 0 The energy Etep consumed for electric taxiing is directly dependent on a stop / start strategy comparable to that which will be retained for a third phase of operation of a rechargeable hybrid vehicle as will be discussed below. Here the chosen strategy defines for each operating point of the vehicle, a quantity called intrinsic gain, which takes as value the difference in gram of fuel per second (g / s) between a quantity representative of a thermal cost and a representative quantity. an electrical cost. The thermal cost is measured in terms of the fuel flow required to drive the vehicle at the present time using the heat engine alone as the pulling means. The electrical cost is measured in terms of the fuel flow required to later recharge the amount of electrical energy that is taken on the electric storage unit 1 to move the vehicle forward at the moment using the single electrical machine (s) as traction means.

The set of operating points of the vehicle where the intrinsic gain takes a positive value, is named ZTEPint (Intrinsic Pure Electric Traction Zone). Ideally, the energy Etep is the energy that makes it possible to realize each point of the set ZTEPint in pure electrical rolling. This strategy also introduces a quantity called Willans specific consumption (CsW) which, for a heat engine, gives in grams the overconsumption associated with an increase or a decrease in the power supplied with a value of 1 kWh. This size has the distinction of being independent of the engine speed. For a full hybrid rechargeable vehicle (FHR for Full Hybrid Rechargeable), the Water and Erecup energy considered in the energy balance are substantially identical to those considered for the FHnR vehicle. On the other hand, a modified energy E'r mth is considered which is recharged differently by the heat engine, a modified energy E'tep which is consumed differently for electric rolling, a modified energy E'del which is consumed differently for the load shedding. engine and a modified energy E'pert which represents other losses of electrical storage. 30 The contribution of a finite energy Er coming from the sector gives a new equation of the energy balance: Waters to Erecup ù Er, mth + E 'tep + E'del + E'pert = Er The question of the strategies of the vehicle FHR is to know if the finite energy Er which is brought by the network at the time of recharging the batteries, is used to: 1) Reduce the energy Ermth of a quantity of energy Er 'which constitutes all or part of the energy energy Er recharged from the sector so as to reduce the recharging by the engine: E'r mth = Er mth - Er1 2) Increase energy Etep of a quantity of energy Erg which constitutes all or part of the energy energy Er recharged from the sector so as to increase the electrical rolling, heat engine off: E'tep = Etep + Er2 3) Increase Edel energy by an amount of energy Er3 which constitutes all or part of the energy Er energy recharged from the mains in order to increase the load shedding by the electric machine eu: Edel + Edel + Er3 The distribution of the finite energy Er which is brought by the network, verifies the law of conservation: Er = Er1 + Er2 + Er3 To evaluate the fuel that the use of Er 20 allows to save, we consider different functions. A function is the function that ensures compliance with the ZTEPint set of operating points of the vehicle where the intrinsic gain takes a positive value until all of the energy Er 25 is consumed. To the three possible uses of the Er energy that we have mentioned above, we need to add a fourth. Indeed, in practice, the vehicle FHnR may not achieve the entire set ZTEPint 30 pure electric driving for lack of availability of electrical energy in the storage. The presence of more energy available therefore also makes it possible to run where the intrinsic gain is positive. This fourth use of Er does not consume power charged to the mains since the fuel gain exists even by recharging this amount of energy by the heat engine, by definition of the positive intrinsic gain that results from a joint increase of energies Ermth and Etep.

Note that this fourth use is to increase the size of the storer of a vehicle FHnR. By imposing on the modified energy E'tep to be consumed for electric running in the form of EZTEPint energy that responds to the ZTEPint set of operating points of the vehicle where the intrinsic gain takes a positive value: E'tep ù EZTEPint The energy recharged by the heat engine is modified as follows: E 'rmthù Ermth + E'tep ù Etep In FIG. 2, the speed of the vehicle is

15 represented on the abscissa and the torque supplied to the wheel is represented on the ordinate. Curve 6 represents the maximum torque that the electric machine can provide. On the curve 6, a horizontal part independent of the speed corresponding to the current is recognized

20 maximum electrical permissible in the engine and a hyperbolic part that corresponds to the maximum power of the electric machine. Curve 7 delimits the upper part of the set ZTEPint of the operating points of the vehicle where the intrinsic gain takes

25 a positive value. The zone contained between the curves 7 and 6 defines operating points of the vehicle where the intrinsic gain takes a negative value.

By expressing in grams each gain obtained on a point during a time interval in which the

The vehicle operates on this point, the amount of fuel Cea saved in grams without consuming the energy Er brought by the network, is given by the formula: TEP r C- = f gain PET Figure 3 can explain a function b The purpose of the invention is to reduce the charging by the heat engine. In order to maintain the level of charge of the storage unit 1 in the case of the vehicle FHnr, the energy supplied by the heat engine 4 is distributed between an energy supplied to the engine. wheel 3 and energy supplied to the electrical machine 5 which then communicates to the storer 1, Er mth energy recharged by the engine. In the case of the vehicle FHR operating the function b, the energy supplied by the heat engine 4 is entirely transmitted to the wheel and the energy returned by the storer 1 to the electric machine 5 to drive the wheel 3, is equal to the difference between the energy Er mth recharged by the engine and the finished energy Er brought from the sector. Er '= Er Constant Etep The amount of fuel Ceb saved with the function b, expressed in grams, is given by the formula. Er CsW Ceb n recharges 3.6 * 106 when the energy is expressed in joules and the specific consumption of Willans CsW is expressed in g / kWh. The coefficient 1lrecharge integrates the efficiency of the electric machine 5 in current generator mode as well as the charging efficiency of the electric storage unit 1. For moderate load powers, this efficiency changes little. We thus establish a saving of fuel per unit of recharged energy. For example with a coefficient (recharge of 30 efficiency equal to 0.8 and a specific Willans CsW consumption of the engine equal to 200g / kWh, or 55.5g / MJ, 1MJ recharged allows a saving of 70g of fuel. formula above, it will be noted that when the efficiency of recharging by the heat engine is unitary, that is to say at its maximum, the saving made by the function b is simply equal to the quantity of equivalent fuel However, the lower the efficiency of charging by the heat engine, the more profitable it is to recharge the battery from a source outside the vehicle, Figure 4 explains a function c which Its purpose is to increase the electric driving priority Erg = Er E 'r mth constant The amount of fuel Cec saved with the function c, is given by the formula: ZTEPint Cee = Er CsW + gain 6 recharge 3, 6 * 10 ZTEPAdditional 1 As in FIG. 2, the vehicle speed is plotted on the abscissa and the wheel torque is plotted on the ordinate. FHRgMJ is called a rechargeable hybrid gain equal to the Cec / Er ratio. The curves 6 and 7 already explained above correspond for example to rechargeable hybrid gains equal to 33g / MJ and 70g / MJ, respectively, for a specific consumption of Willans constantly equal to 200g / kWh. Curve 7 corresponds to a strict application at the boundary of the ZTEPint zone without increasing electric rolling so that Cec = Ceb = 25 70 * Er expressed in grams of fuel when Er is expressed in MJ. The curve 6 corresponds to the maximum of electric rolling achievable and on these points of higher power. The intrinsic gain is such in the example that 1 MJ, spent on a time interval during which it is multiplied by this negative gain, gives a value of -47g to result in 33g after 70g retrenchment. Any electric driving outside the ZTEPint intrinsic pure electric traction zone provides a lower fuel economy than the 35 b function, the gain being by definition less than 0.10 Increasing the electric taxiing therefore achieves fuel savings of less than 70g / MJ. Curve 8 delimits in Figure 4, a pure electric traction zone allowing savings of 44 5 g / MJ. FIG. 5 makes it possible to explain a function d which aims to increase the load shedding of the heat engine. Er-3 = Er E'tep constant 10 The quantity of fuel Ced saved with the function d, is given by the formula: L CsW Ced = Er * ri discharge * 3,6 * 106 In contrast to figure 3, the coefficient hdischarge integrates the efficiency of the electric machine 5 in motor mode as well as the discharge efficiency of the electric storage unit 1 in Figure 5. Depending on the load shedding power considered, this output can degrade sharply. For example with a coefficient q discharge efficiency of 0, 8, in case of low load shedding, and Willans CsW specific consumption of the engine equal to 200g / kWh, 1MJ recharged allows a saving of 44g of fuel. For example with a coefficient q discharge efficiency equal to 0.6, in case of high load shedding, and a Willans CsW specific consumption of the engine equal to 200g / kWh, 1MJ recharged allows a saving of 33g of fuel. The four functions a, b, c, d of use of the energy Er brought by the sector which differentiates the vehicle FHR from the vehicle FHnR, allow different uses of the energy Er to save fuel. As described above, each function quantifies the fuel economy it can generate. The function a allows a fuel economy without consuming Er, it is therefore preferable to always implement it and to ensure the respect of the ZTEPint zone. Among the other functions, the function b allows the greatest fuel economy whatever the vehicle, and the organ yields. Indeed, if we compare the amount of fuel Ceb saved with the function b to the amount of fuel Cec saved with the function c, the formulas explained above give: ZTEPint 10 Cec ù Ceb = Spin which is negative by definition ZTEP supplémen silence of ZTEPint. On the other hand, if we compare the amount of fuel Ceb saved with function b to the amount of fuel Ced saved with function d, the formulas explained above give: Ced / Ceb = llrecharge * ldischarge <1 L ' Er energy must therefore be consumed in priority to perform the function b so as to reduce the recharge by the engine. In the case of a time-limited use, it may happen that the integral utilization of the energy Er as defined by the function b is not possible between two recharges on the sector. Such a situation is detrimental to the fuel consumption of the plug-in hybrid vehicle. Various methods can be implemented to predict this situation and the amount of energy that may not be used. This surplus of energy must first be used as defined by the function c to increase electric driving, until the economy thus achieved is comparable to that of the function obtained by increasing the load shedding. (44 g / MJ in the proposed numerical example). Then, we will begin to perform motor shedding by the function d.

It should be noted that as the load shedding predominates, the discharge efficiency decreases, reducing the fuel economy obtained by Joule used. It is then necessary and jointly continue to increase the electric rolling by means of the function c at the height of the level of economy obtained. In the numerical example, the limiting case at 33g / MJ corresponds to a maximum electric drive of the organic capacities accompanied by a maximum engine load shedding. Different implementation variants are possible. Without prior knowledge of the path to be achieved, Figure 6 shows a panel of strategies that evolves continuously from one strategy to another depending on the amount of energy allocated to the functions c and d. On a real journey, the gain in actual fuel consumption depends on the fuel economy provided by the strategy and the amount of electrical energy consumed at the end of use. The vertical arrow on the left pointing upwards describes a consumption level that makes it possible to use all the extra energy Er during a journey. Consumption is high for a shorter and shorter journey on a longer trip. The downward right vertical arrow describes a time required to utilize all the extra energy Er during a trip. The time is longer as the consumption is low and even shorter as the consumption is high. For low or long-term consumption, strategy 1 is to use only the functions a and b. For average consumption or average duration, strategy 2 consists in using the function c in addition to the functions a and b. For high consumption or short duration, strategy 3 consists in using the function d in addition to the functions a, b and c. FIG. 7 shows the consumption gain obtained with the vehicle FHR with respect to the vehicle FHnR, represented on the ordinate as a function of the running time represented on the abscissa and this for each of the strategies 1, 2, 3 above detailed with reference to FIG. figure 6. Each strategy starts by bringing a gain of consumption increasing according to the running time which saturates then to a constant value. It can be seen that the lower slope strategies culminate in a higher constant value. Thus, at the beginning of the driving time, the strategy 3 which brings about the fastest growing consumption gain is more interesting than the strategy 2, which is itself more interesting than the strategy 1, as shown by the first vertical line most frequently encountered. left. Then strategy 2 passes over strategy 3 when the running time increases as shown by the second vertical line to the right of the first. For high-value rolling times, Strategy 1 dominates Strategies 2 and 3 as shown by the rightmost vertical line in Figure 7.

The choice of the strategy (s) to be used may also result from a statistical study of the rollings in order to determine the relevance of their use. It will be noted that the embodiment explained above refers to the use of additional energy Er from an electricity distribution network. The strategies described are also valid for a hybrid vehicle in which the additional energy comes from another source of internal energy such as a fuel cell for example.

The invention which has just been described, of an essentially strategic nature which does not require any organic modifications, makes it possible to optimize the use of energy from a source other than that which supplies the heat engine, in particular a electrical energy recharged from the network by a rechargeable hybrid vehicle, depending on the path to be achieved. The invention makes it possible to estimate in advance the fuel economy obtained by adding additional electrical energy.

Claims (8)

REVENDICATIONS1. A method of supplying a hybrid powertrain (3, 4, 5) from an internal source of irreversible energy and an internal source of reversible energy (1) which is rechargeable by drawing directly or indirectly from the internal source of irreversible energy and by providing a finite amount of reversible energy from an external source, characterized in that it performs, at least until the said finite quantity is brought, a first function ( a) which controls a power supply from the internal source of reversible energy (1) so as to ensure an intrinsic gain of positive value. 2. Method according to claim 1, characterized in that, at a moment of operation of the powertrain, the intrinsic gain is equal to the difference between a first quantity consumed by supplying the entire powertrain from the internal source of power. irreversible energy at said instant and a second quantity consumed at a later time by drawing directly or indirectly from the irreversible internal source of energy to recharge the internal source of reversible energy (1) when it is used to power the powertrain (3 , 4, 5) in total at the instant. 3. Method according to claim 1 or 2, characterized in that it performs, at least until exhausted of said finite amount provided, a second function (b) which controls a supply from the internal source of reversible energy (1) so as not to draw directly into the internal source of irreversible energy to recharge the internal source of reversible energy (1). 4. Method according to claim 3, characterized in that it performs, at least until exhausting of said finite quantity provided, a third function (c) which controls a supply from the internal source of reversible energy (1). ) so as to quickly exhaust said finished quantity brought. 5. Method according to claim 4, characterized in that it performs, at least until exhausted of said finite quantity provided, a fourth function (d) which controls a supply from the internal source of reversible energy (1). ) so as to minimize the supply from the internal source of irreversible energy. 6. Method according to one of the preceding claims, characterized in that the internal source of reversible energy (1) is of an electrical nature. A system for powering a hybrid power train (3, 4, 5) from an internal source of irreversible energy and an internal source of reversible energy (1) which is rechargeable by drawing directly or indirectly in the internal source of irreversible energy and by providing a finite amount of reversible energy from an external source, characterized in that it is arranged to implement the method according to one of the preceding claims. 8. Vehicle characterized in that it comprises a system according to claim 7.