FR2941054A1 - Rechargeable battery utilization controlling method for engine of car, involves determining value equal to correction to be applied to setpoint voltage value to define next setpoint voltage value, based on average current measurement value - Google Patents

Abstract

The method involves comparing a first value (sigma u) representing a difference between a measured average voltage value (Vu) of a battery and a setpoint voltage value (Uc), and a second value (sigma i) representing an amplitude of variations of current measurement (Im) relative to a measured average current measurement value (Vi), respectively with two threshold values (S1, S2). A third value (DELTA U) equal to a correction to be applied to the setpoint voltage value to define a next setpoint voltage value is determined based on the average current measurement value. An independent claim is also included for a device for controlling utilization of a battery of a machine provided with an alternator, comprising calculation units.

Description

DEVICE AND METHOD FOR STATISTICALLY CONTROLLING THE USE OF A BATTERY OF A GEAR EQUIPPED WITH AN ALTERNATOR BY ACTION ON THE ALTERNATOR SET-UP VOLTAGE The invention relates to machines (generally powered) which are equipped with 'an alternator and a rechargeable battery, and more precisely the control of the use of their battery.

As known to those skilled in the art, it has been proposed to use in some machines, such as vehicles, possibly cars, alternators controlled by a set voltage (or steering). This makes it possible to implement strategies for the management of electrical energy, produced by the alternator, intended to limit as much as possible the energy consumption (generally a fuel) which is necessary for this production of electrical energy. . For example, during a speed acceleration or stabilization phase of a vehicle, each solicitation of its alternator to power an electrical equipment and / or the battery will generate a bias of the powertrain and therefore an overconsumption of fuel . The aforementioned strategies generally aim to limit to the minimum necessary energy that powers the battery (rechargeable). To do this, the battery is generally applied to a fixed regulation voltage (or floating) to maintain its state of charge while minimizing the energy transfer thereon. By way of example, in the case of a lead-acid battery, the regulation voltage is chosen to be substantially equal to 13.2 V. This fixed value of the regulation voltage is chosen as a function of an average type of new battery. Unfortunately, the batteries are aging, and therefore the fixed regulating voltage that is used quickly becomes unsuitable. It would certainly be possible to take into account the aging of the batteries, but, unfortunately, this aging can vary according to the type of the battery.

Moreover, when one applies the floating voltage (or regulation) one can only guarantee that the energy entering into the battery will be minimal. However, when the battery aged this fixed regulation voltage value may cause its automatic discharge.

The invention therefore aims to propose a new alternative solution based on statistical calculations, which does not have the aforementioned drawbacks of the solutions of the prior art. It proposes more specifically for this purpose a method, dedicated to controlling the use of a battery of a machine equipped with an alternator whose operation is controlled by a setpoint voltage (or control) (Uc), during a phase of use of this alternator. This method is characterized in that it comprises the steps of: - determining first (Vu) and second (Vi) values, representative of average values during a chosen duration respectively of voltage measurements (Um) and measurements of current (lm) of the battery, then a third value (au) representative of the difference between the first value (Vu) and the current setpoint voltage (Uc), and a fourth value (ai) representative of the amplitude of the variations during the chosen duration of current measurements (lm) with respect to the second value (Vi), - to compare the third (au) and fourth (ai) values respectively at first and second thresholds, and - when the third (a) au) and fourth (ai) values are respectively lower than the first (Si) and second (S2) thresholds, to determine a fifth value (AU) function of the second value (Vi) and equal to the correction to be applied to the voltage of deposit (Uc) in course to set the next setpoint voltage to be applied. The method according to the invention may comprise other characteristics that can be taken separately or in combination, and in particular: the first (Vu) and second (Vi) values can be quadratic averages; the third (au) and fourth (ai) values can be standard deviations; the target voltage (Up) can be determined as a function of at least one variable which is chosen from a group comprising at least the external temperature, the state of charge of the battery and the state of charge of the alternator .

The invention also proposes a device dedicated to the control of the use of a battery of a machine equipped with an alternator whose operation is controlled by a setpoint voltage (or control) (Uc), during a phase of use of this alternator. This device is characterized in that it comprises: first calculation means responsible for determining a first value (Vu), representative of an average value during a chosen duration of voltage measurements (Um) of the battery, and a third value (au), representative of the difference between the first value (Vu) and the current setpoint voltage (Uc), and to compare this third value (au) with a first threshold, - second loaded calculation means determining a second value (Vi) representative of an average value during the selected duration of current measurements (lm) of the battery, and a fourth value (ai) representative of the amplitude of the variations during this selected duration of measurements of current (lm) with respect to the second value (Vi), and comparing the fourth value (ai) with a second threshold, and - the third loaded calculation means, when the third (au) and fourth (ai) values are lower r at the first and second thresholds, to determine a fifth value (AU) which is a function of the second value (Vi) and equal to the correction to be applied to the current setpoint voltage (Uc) to define the next setpoint voltage to be applied. The device according to the invention can comprise other characteristics that can be taken separately or in combination, and in particular: its first and second calculation means can be responsible for determining respectively first (Vu) and second (Vi) values of quadratic mean type; its first and second calculation means can be responsible for determining third (au) and fourth (ai) standard deviation type values, respectively; it may comprise fourth calculation means responsible for determining the target voltage (Uc) as a function of at least one variable selected from a group comprising at least the external temperature, the state of charge of the battery and the state load of the alternator. Other features and advantages of the invention will become apparent on examining the detailed description below, and the accompanying drawings, in which: FIG. 1 diagrammatically and functionally illustrates an example of a control device according to the integrated invention; in an onboard computer of a motor vehicle, and - Figure 2 schematically illustrates the main steps of an exemplary algorithm for implementing the method of the invention. The attached drawings may not only serve to complete the invention, but also contribute to its definition, if any. The purpose of the invention is to enable the control of the use of a battery (B) of a machine (V) which is equipped with an alternator (A) whose operation is controlled by a set voltage (or piloting), at least during a phase of use of this alternator (A). In the following, we consider, by way of non-limiting example, that the vehicle is a motor vehicle, such as a car. But, the invention is not limited to this type of machine. It concerns indeed any type of machine including a motor, an alternator and a rechargeable battery. Therefore, it may include a land vehicle (possibly automotive), maritime or space, or a machine. FIG. 1 shows schematically and functionally a car (vehicle) V comprising an on-board computer OB, an alternator A and a rechargeable battery B. The battery B can for example be recharged conventionally thanks to the current that is supplied by the alternator A, which operates thanks to the motor (not shown) of the car V. The invention proposes to implement in the car (vehicle) V a control device D responsible for controlling the use of the battery B, in particular when the alternator A is biased, for example during a phase of acceleration or speed stabilization of the car V. In the nonlimiting example illustrated in FIG. 1, the (control) device D is implanted in FIG. OB on-board computer. But, this is not mandatory. It can indeed be implanted in another organ of the car V, such as for example (and not limited to) in a computer, coupled to the on-board computer OB. A device D according to the invention comprises at least a first calculation module MC1, a second calculation module MC2 and a third calculation module MC3. It intervenes automatically or on order (for example from the OB on-board computer) whenever the alternator A is requested by the power train of the car V and at the same time at least one electrical component of the car V needs electrical power to operate. The first calculation module MC1 is first of all responsible for determining whether the voltage has undergone significant variations during a selected duration Dc (or observation time (or window)). To do this, it determines (or calculates) a first value Vu which is representative of an average value, during the chosen duration Dc, of voltage measurements Um of the battery B. It will be noted that it is not necessary to storing (for example in a buffer-type memory) all the voltage measurements Um received during the chosen duration Dc, if the first value Vu is calculated by a recursive method. This chosen duration Dc is for example equal to (at least) two seconds (2 s). It is chosen so as to obtain a number of significant measurement samples.

The voltage measurements Um are for example carried out periodically (for example every 100 ms), by a CT sensor which is coupled to the battery B. It will be noted that the CT sensor can provide the voltage measurements Um either directly to the first module of FIG. calculation MC1, that is to the on-board computer OB, which is then responsible for communicating them to the first calculation module MC1 (as illustrated without limitation in FIG. 1). By way of non-limiting example, the first value Vu can be a root mean square. But other types of average value can be determined, such as for example a mean value per square least or by filtering. The first calculation module MC1 is also responsible for determining (or calculating) a third value at which is representative of the difference between the first value Vu and the current setpoint voltage Uc. By way of non-limiting example, the third value may be a standard deviation. But other types of statistical value representative of an amplitude of variation can be determined. Finally, the first calculation module MC1 is also responsible for comparing the third value with a first threshold S1 chosen, and outputting data (for example numeric) representative of the result of its comparison (for example at <S1 corresponds to a binary value equal to 0 and S1 corresponds to a binary value equal to 1). The second calculation module MC2 preferably works substantially at the same time as the first calculation module MC1. This second calculation module MC2 is first of all responsible for determining (or calculating) a second value Vi which is representative of a mean value, during the selected duration Dc, of current measurements lm of the battery B. To do this it can for example store in a buffer memory all current measurements lm it receives for the selected duration Dc. The current measurements lm are for example carried out periodically (for example every 100 ms (as the voltage measurements Um)), by a sensor which is coupled to the battery B. In the nonlimiting exemplary embodiment illustrated in FIG. 1, it is the same CT sensor that performs the current measurements lm and the voltage measurements Um. But this is not obligatory. One could indeed use two different sensors to respectively perform the current measurements lm and the voltage measurements Um. It will be noted that the CT sensor can provide the current measurements lm either directly to the second calculation module MC2, or to the on-board computer OB, which is then responsible for communicating them to the second calculation module MC2 (as shown in non-limiting manner on FIG. figure 1). By way of non-limiting example, the second value Vi can be a root mean square. But other types of average value can be determined, such as for example a mean value per square least or by filtering.

The second calculation module MC2 is also responsible for determining (or calculating) a fourth value ai which is representative of the amplitude of the variations of the current measurements lm, received during the selected duration Dc, with respect to the second value Vi. By way of non-limiting example, the fourth value ai may be a standard deviation. But other types of statistical value representative of an amplitude of variation can be determined. Finally, the second calculation module MC2 is also responsible for comparing the fourth value ai with a second threshold S2 chosen, and outputting data (for example numeric) representative of the result of its comparison (for example 61 <S2 corresponds to a binary value equal to 0 and 61 S2 corresponds to a binary value equal to 1). It is important to note that the first MC1 and second MC2 calculation modules can possibly constitute two sub-parts of the same calculation module.

The third calculation module MC3 intervenes when the third value at computed by the first calculation module MC1 is lower than the first threshold S1. Indeed, in this case the difference between the first value Vu and the setpoint voltage Uc is low, which means that there has been no significant variation in voltage following a switching on or off of a device 3o consumption of electricity (which invalidates the measurement of current performed substantially simultaneously by the second calculation module MC2). The second value Vi can then be used to calculate the correction to be made to the setpoint voltage Uc if this is necessary.

It is recalled that the invention is intended to serve during voltage stability phases during which the voltage and current measurements can be taken into account without risk. If the third value α is less than the first threshold S1, and at the same time the fourth value ai (calculated by the second calculation module MC2) is smaller than the second threshold S2, then the third calculation module MC3 determines a fifth value AU which is equal to the correction (or offset (or offset)) that will have to be applied (added or subtracted according to its sign) to the current setpoint voltage Uc to define the next setpoint voltage to be applied. This fifth value AU is a function of the second value Vi. Indeed, if one wants to maintain the state of charge of the battery B, it is necessary that it does not accept current (load) or does not deliver current (discharge). To do this, it is necessary that the average current (or second value) Vi is close to zero. If this average current Vi is negative, it means that the battery B delivers current and therefore discharges. The voltage at the terminals of the battery B is too low and therefore it is necessary to add a positive voltage offset (or offset) (fifth value) AU, proportional to the average current Vi discharged by the battery B, to the value of the nominal voltage Uc to define the new set voltage (or control) Uc of the alternator A, to allow the battery B to return to a state of equilibrium. On the other hand, if the average current Vi is positive, it means that the battery B is recharging. The voltage at the terminals of the battery B is too high and therefore it is necessary to subtract a voltage offset (or offset) (fifth value) AU positive, proportional to the average current Vi which supplies the battery B, to the value of the nominal voltage Uc to define the new set voltage (or control) Uc of the alternator A, to allow the battery B to return to a state of equilibrium.

It will be understood that this strategy advantageously makes it possible to keep the battery B in a state of equilibrium independently of its aging and of its type. It is important to note that the third calculation module MC3 may possibly constitute a sub-part of a calculation module also comprising the first MC1 and second MC2 calculation modules. As illustrated nonlimitingly in FIG. 1, the device D may optionally comprise a fourth calculation module MC4 responsible for determining the setpoint voltage Uc of the alternator A as a function of at least one chosen variable. Each variable may for example be chosen from at least the external temperature, the state of charge of the battery B and the state of charge of the alternator A, which are for example provided by the on-board computer OB.

Note that in an alternative embodiment not shown, the set voltage Uc of the alternator A could be determined by a module which is not part of the device D, but which uses the fifth AU values that it determines. Moreover, and as shown in non-limiting manner in FIG. 1, when the device D comprises a fourth calculation module MC4, it can optionally and also include a combination module MCN responsible for adding to the setpoint voltage (or control) Uc in progress the fifth value AU to constitute the new setpoint voltage (or control) Uc of the alternator A. It will be understood that here is meant by adding the fact of adding a fifth value AU which is either positive (which leads to an increase in Uc), which is negative (which leads to a decrease in Uc). It is important to note that the fourth calculation module MC4 and the combination module MCN may possibly be grouped together in one and the same module which may possibly constitute a sub-part of a global module also comprising the first MC1, second MC2 and third MC3 calculation modules. It is important to note that the invention can also be considered from the angle of a method of controlling the use of a battery B, which can be implemented in particular by means of a control device D of the type from the one presented above. Since the functionalities offered by the implementation of the method according to the invention are identical to those offered by the control device D presented above, only the combination of main functionalities offered by the method is presented hereinafter. As illustrated without limitation in the algorithm of FIG. 2, the method starts with a step 10 in which the first Vm and the second Vi are calculated, representative of average values, during a selected duration Dc, respectively of measurements of Um voltage and current measurements lm of the battery BA, then a third value at which is representative of the difference between the first value Vu and the current setpoint voltage (or control) Uc, and a fourth value ai which is representative of an amplitude of variations during the selected duration Dc of current measurements lm with respect to the second value Vi. It will be noted that the various calculations are preferably done in parallel (substantially simultaneously). The method continues with a step 20 in which the third to fourth values are compared with first thresholds S1 and second S2, respectively. If the third value at is greater than the first threshold S1, then nothing is done and the eventual return to step 10 if a new check is to be made. On the other hand, if the third value is smaller than the first threshold S1, then we look at the result of the comparison of the fourth value ai with the second threshold S2. If the fourth value ai is greater than the second threshold S2 then nothing is done and we eventually return to step 10 if a new check must be made. On the other hand, if the fourth value ai is smaller than the second threshold S2, then a fifth value AU is determined in a step 30 which is a function of the second value Vi and equal to the correction to be applied to the current setpoint voltage Uc for define the next set voltage to be applied to the alternator A. The method according to the invention may optionally comprise, as illustrated a step 40 in which the target voltage Uc is determined as a function of at least one variable (as indicated in FIG. -before). This step 40 may be carried out substantially in parallel with the other steps 10 to 30. When the method comprises a step 40, it is advantageous that it also comprises, as illustrated, a step 50 in which, it is added to the setpoint voltage Uc in progress (determined in step 40) the fifth value AU (determined in step 30) to constitute the new set voltage (or control) Uc of the alternator A.

The invention offers several advantages over solutions of the prior art, and in particular: it makes it possible to overcome the problems induced by the aging of the batteries. Indeed, the proposed statistical treatment makes it possible to overcome the dependence of the voltage of the battery according to its state of charge which is itself a function of the state of aging. It is indeed recalled that the no-load voltage of the battery for a given state of charge evolves as a function of aging and the type of the latter, - it allows to preserve the battery because it avoids it to make the object of overloads, - it allows to limit the consumption of energy (fuel) because it works closer to the actual control voltage (floating). The invention is not limited to device embodiments and method of controlling the use of a battery described above, only by way of example, but it encompasses all variants that may be considered by the man of art within the scope of the claims below.

Claims (8)

REVENDICATIONS1. Method for controlling the use of a battery (B) of a machine (V) equipped with an alternator (A) controlled by a set voltage (Uc), during a phase of use of said alternator ( A), characterized in that it comprises the steps of: i) determining first (Vu) and second (Vi) values, representative of average values during a selected duration respectively of voltage measurements (Um) and measurements of current (lm) of the battery (BA), then a third value (au) representative of the difference between said first value (Vu) and the current setpoint voltage (Uc), and a fourth value (ai) representative of an amplitude of variations during said selected duration of current measurements (lm) with respect to said second value (Vi), ii) comparing said third (au) and fourth (ai) values respectively with first (Si) and second ( S2) thresholds, and iii) when said third (to) and fourth me (ai) values are respectively lower than the first (Si) and second (S2) thresholds, to determine a fifth value (AU) according to said second value (Vi) and equal to the correction to be applied to said setpoint voltage (Uc) ) in progress to set the next setpoint voltage to be applied. 2. Method according to claim 1, characterized in that said first (Vu) and second (Vi) values are quadratic averages. 3. Method according to one of claims 1 and 2, characterized in that said third (au) and fourth (ai) values are standard deviations. 4. Method according to one of claims 1 to 3, characterized in that said determined voltage (Uc) is determined as a function of at least one variable selected from a group comprising at least the external temperature, the state battery charge (B) and alternator charge status (A). 5. Device (D) for monitoring the use of a battery (B) of a machine (V) equipped with an alternator (A) controlled by a set voltage (Uc), during a phase d use of said alternator (A), characterized in that it comprises: i) first calculation means (MC1) arranged for determining a first value (Vu) representative of an average value during a chosen duration of voltage measurements ( Um) of the battery (BA), and a third value (au), representative of the difference between said first value (Vu) and the current setpoint voltage (Uc), and to compare said third value (au) with a first threshold (Si), ii) second computing means (MC2) arranged to determine a second value (Vi) representative of a mean value during said selected duration of current measurements (lm) of the battery (BA), and a fourth value (ai) representative of the amplitude of the variations during said chosen duration of said current measurements (lm) with respect to said second value (Vi), and for comparing said fourth value (ai) with a second threshold (S2), and iii) third computing means (MC3) arranged, when said third (au) and fourth (ai) values are respectively lower than said first (Si) and second (S2) thresholds, to determine a fifth value (AU) according to the second value (Vi) and equal to a correction to be applied to said voltage current setpoint (Uc) to set the next setpoint voltage to be applied. 6. Device according to claim 5, characterized in that said first (MC1) and second (MC2) calculating means are arranged to respectively determine first (Vu) and second (Vi) values of root mean square type. 7. Device according to one of claims 5 and 6, characterized in that said first (MC1) and second (MC2) calculating means are arranged to determine respectively third (au) and fourth (ai) standard deviation type values. . 8. Device according to one of claims 5 to 7, characterized in that it comprises fourth calculation means (MC4) arranged to determine said setpoint voltage (Uc) according to at least one variable selected from a group comprising at least the external temperature, the state of charge of the battery (B) and the state of charge of the alternator (A).