Method for controlling a motor vehicle alternator

Abstract

The invention relates to a method for controlling an alternator electrically connected to a battery of a motor vehicle and to a first electrical network of the motor vehicle, comprising: - a first step (E1) of operating the alternator according to a first mode in which a first electrical current produced by the alternator supplies the first electrical network, and the battery in order to recharge same; - a second step (E2) of detecting a driving situation that requires limiting an intensity of a current flowing in a rotor of the alternator to a first maximum intensity value; and then - a third step (E3) of operating the alternator according to a second mode in which a second electrical current produced by the alternator supplies only the first electrical network, an intensity of a third electrical current flowing in the rotor of the alternator in order to produce the second electrical current being lower than the first maximum intensity value.

Description

[0001] DESCRIPTION

[0002] TITLE: Method for controlling a motor vehicle alternator.

[0003] The invention relates to a method for controlling a motor vehicle alternator. The invention also relates to a device for controlling a motor vehicle alternator. The invention further relates to a motor vehicle equipped with such a control device. The invention also relates to a computer program implementing the mentioned method. The invention finally relates to a recording medium on which such a program is recorded.

[0004] Internal combustion engine vehicles must meet a need to reduce their fuel consumption while supplying electricity to an increasing number of devices, including lighting functions, passenger compartment thermal comfort management systems, driver assistance systems and multimedia systems including connected services.

[0005] The torque generated by the combustion engine must therefore provide the energy necessary to move the vehicle, but also provide sufficient energy to an alternator to recharge the battery and supply power to the vehicle's equipment. However, it may happen that the torque generated by the combustion engine is not sufficient to simultaneously cover all the needs previously described.

[0006] There are solutions to improve electrical energy management. However, these solutions have drawbacks.

[0007] The aim of the invention is to provide a device and a method for controlling a motor vehicle alternator which overcomes the drawbacks mentioned above and improves the devices and methods for controlling a motor vehicle alternator known from the prior art. In particular, the invention makes it possible to produce a device and a method which are simple and reliable and which optimize the management of electrical energy.

[0008] To this end, the invention relates to a method for controlling an alternator electrically connected to a battery of a motor vehicle and to a first electrical network of the motor vehicle, comprising:

[0009] - a first stage of operation of the alternator according to a first mode in which a first electric current produced by the alternator supplies the first electrical network, and the battery for its recharging,

[0010] - a second step of detecting a driving situation requiring limiting the intensity of a current flowing in a rotor of the alternator to a first maximum intensity value, then

[0011] - a third stage of operation of the alternator according to a second mode in which a second electric current produced by the alternator supplies only the first electrical network.

[0012] In addition, an intensity of a third electric current flowing in the rotor of the alternator to produce the second electric current is less than the first maximum intensity value.

[0013] In one embodiment, the first maximum intensity value is determined as a function of a rotation speed of the heat engine.

[0014] In one embodiment, the first electrical network is a low-voltage network, in particular a network whose voltage varies between 12V and 14V, or even between 12V and 15.6V, supplying a set of equipment of a motor vehicle, the set of equipment comprising an anti-lock braking system for the wheels and / or a system for adjusting the seats of a passenger compartment and / or a lighting management system and / or a system for managing thermal comfort of the passenger compartment and / or a driving assistance system and / or multimedia systems. In one embodiment, the first step and the third step implement a regulation loop between a voltage setpoint transmitted to the alternator and a voltage measured at the terminals of the first electrical network.

[0015] In one embodiment, the first step comprises an application by the alternator of a first voltage to the terminals of the first electrical network, the first voltage being strictly greater than a reference voltage of the battery, the reference voltage of the battery corresponding to a voltage value causing neither charging nor discharging of the battery when it is applied to the terminals of the battery.

[0016] In addition, the third step includes an application by the alternator of a second voltage to the terminals of the first electrical network, the second voltage being less than or equal to the reference voltage of the battery.

[0017] Furthermore, if the second voltage is strictly lower than the reference voltage of the battery, then the third step includes a supply, by the battery, of a fourth electric current supplying the first electrical network.

[0018] In one embodiment, the second step comprises a verification of conditions for applying a limitation of the intensity of the current flowing in the rotor of the alternator, comprising:

[0019] - a sub-step of comparing a rotation speed of the heat engine to a first rotation speed threshold of the heat engine, and

[0020] - a sub-step of comparing a temperature of the heat engine to a first temperature threshold of the heat engine, and

[0021] - a sub-step of comparing a battery charge level to a first battery charge threshold. In one embodiment, the method further comprises a fourth step of detecting an end of limitation of an intensity of a current produced by the alternator comprising

[0022] - a sub-step of comparing a current rotation speed of the heat engine to the first rotation speed threshold of the heat engine,

[0023] - a sub-step of comparing a temperature of the heat engine to a second temperature threshold of the heat engine,

[0024] - a sub-step of comparing a current charge level of the battery to a second charge threshold of the battery, the second temperature threshold of the heat engine being strictly lower than the first temperature threshold of the heat engine, and the second charge threshold of the battery being strictly lower than the first charge threshold of the battery.

[0025] In one embodiment, the second step comprises determining a second maximum value of a motor torque necessary to generate a circulation in the rotor of a current of an intensity equal to the first maximum intensity value, and transmitting the second maximum value to the heat engine.

[0026] The invention further relates to a device for controlling an alternator electrically connected to a battery of a motor vehicle and to a first electrical network of the motor vehicle, the device comprising hardware and / or software elements implementing the method according to the invention, in particular hardware and / or software elements designed to implement the method according to the invention, and / or the device comprising means for implementing the steps of the method according to the invention.

[0027] The invention further relates to a motor vehicle equipped with a device for controlling an alternator according to the invention. The attached drawing represents, by way of example, an embodiment of a control device according to the invention and an embodiment of a control method according to the invention.

[0028] Figure 1 is a first representation of a motor vehicle equipped with an embodiment of a control device according to the invention.

[0029] Figure 2 is a second representation of a motor vehicle equipped with an embodiment of a control device according to the invention.

[0030] Figure 3 is a third representation of a motor vehicle equipped with an embodiment of a control device according to the invention.

[0031] Figure 4 is a flowchart of a control method according to the invention.

[0032] Figure 5 is a graph for determining the maximum intensity of a current applied to an alternator rotor as a function of the rotation speed of a motor driving the alternator.

[0033] Figure 6 is a chart for determining the maximum intensity of a current applied to an alternator rotor as a function of the rotation speed of a motor driving the alternator and the current supplied by the alternator.

[0034] Figure 7 is a graph for determining the start and end of the limitation of a maximum intensity of a current applied to an alternator rotor as a function of the temperature of a coolant of an engine driving the alternator.

[0035] Figure 8 is a graph for determining the start and end of a limitation of a maximum intensity of a current applied to an alternator rotor as a function of a state of charge of a battery supplied by the alternator.

[0036] An example of a motor vehicle 100 equipped with an embodiment of a device 10 for controlling an alternator is described below with reference to FIGS. 1 to 8.

[0037] The motor vehicle 100 may be a vehicle of any type, for example a passenger vehicle or a utility vehicle or a public transport vehicle. The motor vehicle 100 is equipped with a heat engine 1 and an alternator 2 transforming part of the engine torque provided by the heat engine 1 to generate a current. In one embodiment, the motor vehicle 100 may be a heat vehicle equipped with micro-hybridization.

[0038] As shown diagrammatically in Figure 2, the heat engine 1 provides a first engine torque C1 to the drive train comprising a clutch 7, a gearbox 8 and drive wheels 9. In addition, the engine 1 provides a second engine torque C2 to the alternator of the device 10.

[0039] The device 10 further comprises a battery 3, the alternator 2 being electrically connected to the battery 3 for recharging. In the embodiment described, the battery 3 is a so-called low voltage battery, in particular a battery called a “12 Volt battery”.

[0040] Furthermore, the alternator 2 and the battery 3 are both electrically connected to a first network 4, called electrical network 4 or network 4 in the remainder of the document.

[0041] The electrical network 4 is a network supplying a set of equipment of the motor vehicle 100, the set of equipment comprising an anti-lock braking system 41 for the wheels and / or a system 42 for adjusting the seats of a passenger compartment and / or a system 43 for managing lighting and / or a system 44 for managing thermal comfort of the passenger compartment and / or a system 45 for driving assistance and / or multimedia systems 46.

[0042] In one embodiment of the invention, the electrical network 4 supplies all the electrical and electronic components of the motor vehicle 100 except the components used for traction of the vehicle.

[0043] Network 4 is a so-called low-voltage network, whose voltage is regulated to vary around 13 Volts, in particular a network whose voltage varies between 12V and 14V, or even between 12V and 15.6V. Advantageously, the voltage regulation is implemented by a voltage regulator 21 integrated into the alternator 2.

[0044] Figure 3 schematically represents an embodiment of an electrical architecture of the device 10 electrically connected to the network 4.

[0045] The device 10 comprises a control unit 5 capable of controlling a voltage U_C to be applied to the terminals of the network 4 and a maximum intensity l_rotor_max of a current flowing in a rotor 22 of the alternator 2. The alternator 2 receives the voltage U_C and intensity l_rotor_max commands from which it generates a current of limited intensity and voltage U_A, the voltage U_A being advantageously close to the voltage U_C. Then, the control unit 5 receives, in a feedback loop, a measurement of the voltage U_A, applied to the terminals of the network 4. The feedback loop thus allows the control unit 5, by correcting the command U_C, to reduce a difference observed between a desired voltage at the terminals of the network 4 and a voltage applied to the terminals of the network 4.As a note, by convention, when the intensity l_rotor_max of the rotor current is zero this means that the intensity of the rotor current is not limited, and consequently that the intensity of the current generated by alternator 2 is not limited.

[0046] In the remainder of the document, the expressions “driving situation” or “operating point” are used to designate conditions of use of the motor vehicle 100 which are likely to be taken into account by the device 10 for controlling the alternator 2 to limit the intensity of the current generated by the alternator 2.

[0047] The conditions of use of the motor vehicle 100 at a given time include in particular:

[0048] - a state of charge of battery 3 at the given time, and / or

[0049] - a temperature of the heat engine 1 or a temperature of a coolant of the heat engine 1 at the given time, and / or

[0050] - a rotation speed of the heat engine 1 at the given instant, and / or

[0051] - a speed and / or acceleration command issued at a given moment by a driver or an automatic speed regulation system,

[0052] - commands for using passenger compartment equipment at a given moment, for example adjusting a seat, starting air conditioning,

[0053] - an outside temperature at a given time,

[0054] - a type or topology, in particular a slope, of a traffic lane on which the vehicle is traveling at the given time.

[0055] The alternator control device 10 advantageously comprises means 6 for determining the conditions of use of the motor vehicle 100, in particular

[0056] - a means for determining a temperature 61 of a coolant of the thermal engine,

[0057] - a means 62 for determining an outside air temperature, - a means 63 for determining a type or topology of a traffic lane which may be a geolocation system associated with a map.

[0058] In certain driving situations, it is necessary to limit the engine torque taken by the alternator 2 in order to give priority to the engine torque allocated to a powertrain of the motor vehicle 100. The vehicle is however designed so that the limitation of the engine torque taken by the alternator 2 does not impact the operation of the equipment supplied by the network 4. In other words, the power of the thermal engine 1 is calibrated so that the limitation of the engine torque taken by the alternator 2 does not limit the intensity of the current supplying the network 4 and only impacts the recharging of the battery 3.

[0059] In the described embodiment, the control device 10 comprises an engine control module 101.

[0060] The engine control module 101 makes it possible to determine a need to limit the engine torque C2 allocated to the alternator 2. In return, the control device 10 informs the engine control module 101 of an effective limitation of the engine torque C2 by communicating a maximum engine torque that the alternator will draw at most, without ever exceeding it.

[0061] The control device 10 may also comprise a module 102 for controlling the equipment of the network 4. The module 102 may in particular determine the energy consumption required by the equipment of the network 4.

[0062] The control device 10 comprises means for implementing a control method according to the invention, in particular a processing unit 5, comprising a microprocessor 51, a memory 52 and communication interfaces 53. The microprocessor 51 mainly comprises the following modules which cooperate with each other:

[0063] - a module 511 for operating the alternator 2 according to a first mode M1, this module being able to cooperate with the engine 1,

[0064] - a module 512 for detecting a driving situation requiring limiting an intensity of the current produced by the alternator, this module being able to cooperate with the engine control module 101, the equipment control module 102, and the determination means 6,

[0065] - a module 513 for operating the alternator 2 according to a second mode M2, this module being able to cooperate with the engine 1,

[0066] - a module 514 for detecting the end of limitation of an intensity of a current produced by the alternator 2, this module being able to cooperate with the engine 1.

[0067] The motor vehicle 100, in particular the control device 10, preferably comprises all the hardware and / or software elements configured so as to implement the method defined in the subject of the invention or the method described below.

[0068] A first mode of execution of a control method is described below with reference to Figure 4. The method according to the invention comprises steps E1 to E4 which are executed successively.

[0069] In the first step E1, the alternator 2 operates according to a first mode M1 in which the electric current produced by the alternator supplies the first electrical network 4, and the battery 3 for its recharging.

[0070] The first step E1 comprises an application of a first voltage U_1 to the terminals of the first network 4, the first voltage U_1 being strictly greater than a reference voltage U_ref of the battery 3, the reference voltage of the battery U_ref corresponding to a voltage value causing neither charging nor discharging of the battery when it is applied to the terminals of the battery 3.

[0071] For this, in the first step E1, the controller 5 transmits to the alternator 2 a voltage command U_C_1 applicable to the network terminals.

[0072] The voltage command U_C_1 is defined so that a voltage U_1 of the current generated by the alternator 2 will be strictly higher than a reference voltage of the battery U_ref.

[0073] The voltage U_1 of the current supplied by the alternator 2 being higher than the reference voltage of the battery U_ref, the current from the alternator 2 is used to supply not only the network 4, but also the battery 3, for its recharging.

[0074] Advantageously, the first step E1 comprises an implementation of a regulation loop between the voltage setpoint U_C_1 - transmitted by the controller to the alternator 2 - and the voltage U_1 measured at the terminals of the battery 3.

[0075] When the alternator 2 operates according to the first mode M1, the intensity of a third current flowing in the rotor 22 of the alternator 2 is not limited. The third current is called "rotor current" in the remainder of the document. The rotor current is generated by the regulator 21 of the alternator according to the setpoint U_C_1.

[0076] In certain driving situations, it is necessary to limit the torque C2, which implies limiting the rotor current, as described in the following steps of the method. We continue with step E2 of detecting a driving situation requiring limiting an intensity of a current flowing in a rotor 22 of the alternator 2 to a first maximum intensity value l_rotor_max,

[0077] In other words, in the second step E2, the controller 5 evaluates a need and a feasibility of limiting the engine torque taken by the alternator 2 to produce the electricity consumed on the network 4 and optionally supply the battery 3.

[0078] In the embodiment described, the detection of a need to limit the engine torque taken by the alternator 2 is implemented by the engine control module 101. A request to limit the engine torque taken by the alternator is then sent by the control module 101 to the control unit 5.

[0079] Upon receipt of such a request, we move on to an assessment of the feasibility of limiting the engine torque taken by alternator 2.

[0080] The equipment control module 102 makes it possible to check that the electrical energy consumed by the network 4 is less than the maximum flow rate of the alternator 2.

[0081] Furthermore, in step E2, we check that battery 3 is sufficiently charged to withstand not being recharged by the alternator immediately.

[0082] These checks make it possible to determine, on the one hand, that a limitation of the flow rate of the alternator is possible, and on the other hand, that it is possible to defer a recharge of the battery. Advantageously, the battery 3 can contain a reserve of electrical energy which will make it possible to smooth out the effects of the limitation. In one embodiment, the second step E2 comprises a verification of conditions for applying a limitation of the intensity of the current produced by the alternator 2 comprising:

[0083] - a sub-step E21 of comparing a current rotation speed of the heat engine 1 with a first threshold S11 of rotation speed of the heat engine 1, and

[0084] - a sub-step E22 of comparing a temperature of the heat engine 1 to a first temperature threshold S21 of the heat engine 1, and

[0085] - a sub-step E23 for comparing a current charge level of the battery 3 with a first battery charge threshold S31.

[0086] An embodiment of sub-step E21 is illustrated by graph G1 of figure 5. Graph G1 determines a maximum intensity of the rotor current l_rotor_max (expressed in Amperes on the y1 axis) as a function of a current rotation speed of the heat engine 1 (expressed in revolutions per minute on the x1 axis).

[0087] The graph G1 represents a piecewise affine function comprising five pieces G11, G12, G13, G14, G15. The numerical values ​​represented in the graph G1 are given as an example and may vary depending on the embodiment of the invention.

[0088] The first piece G11 defines a first range P11 of rotation speed values ​​of the heat engine 1 over which a maximum intensity l_rotor_max is substantially constant and equal to 0.1 Ampere for rotation speed values ​​of the heat engine 1 between 0 and 700 revolutions per minute.

[0089] The second piece G12 defines a second range P12 of rotation speed values ​​of the thermal engine 1 on which a maximum intensity l_rotor_max increases very quickly towards a value of 3.4 Amperes for an engine rotation speed between 700 and 750 revolutions per minute.

[0090] The third piece G13 represents a plateau on a third range P13 of rotation speed values ​​of the thermal engine 1, on which the maximum intensity l_rotor_max is constant and equal to 3.4 Amperes when the rotation speed of the engine is between 750 and 1000 revolutions per minute.

[0091] The fourth piece G14 defines a fourth range P14 of rotation speed values ​​of the thermal engine 1 on which a maximum intensity l_rotor_max increases slightly up to 4 Amps when the rotation speed of the engine varies between 1000 revolutions per minute and 1450 revolutions per minute.

[0092] The fifth piece G15 defines a fifth range P15 of rotation speed values ​​of the thermal engine 1 on which a maximum intensity l_rotor_max is zero when the rotation speed of the engine is greater than 1455 revolutions per minute. In other words, the limitation of the intensity of the current generated by the alternator is not applicable when the rotation speed of the thermal engine 1 is greater than the first threshold S11, i.e. 1455 revolutions per minute.

[0093] Figure 6 represents a chart allowing to associate a maximum intensity of the rotor current (expressed in Amperes) with a rotation speed of the rotor of the alternator (in revolutions per minute) and with an intensity of a current delivered by the alternator (in Amperes). The chart represented in the example of Figure 6 is applicable to a so-called "120 Ampere" alternator (i.e. guaranteeing a supply of an intensity of at least 120 Amperes) operating at 20 degrees. In addition, the line LO of the table provides a correspondence between the rotation speed of the rotor 22 in revolutions per minute and the rotation speed of the thermal engine 1 in revolutions per minute. The ranges P11, P13, P14 and P15 of rotor rotation speed values ​​defined in Figure 5 are also represented in Figure 6.

[0094] In particular, the abacus represents

[0095] - the P13 range of rotation speed values ​​of the thermal engine 1, over which the maximum current l_rotor_max is constant and equal to 3.4 Amperes when the rotation speed of the engine is between 750 and 1000 revolutions per minute, and

[0096] - the P14 range of rotation speed values ​​of the thermal engine 1 on which a maximum intensity l_rotor_max increases slightly up to 4 Amps when the rotation speed of the engine varies between 1000 revolutions per minute and 1666 revolutions per minute.

[0097] Thus, graph G1 makes it possible to determine whether the heat engine 1 is operating at an engine speed within the ranges of values ​​over which a limitation of the rotor current may be necessary, i.e. whether the engine speed is within the ranges of values ​​P11 to P14. In addition, the chart shown in Figure 6 makes it possible to associate a maximum intensity of the rotor current with the current rotation speed of the heat engine 1.

[0098] Advantageously, in sub-step E21 a second maximum value max_C2 of a motor torque necessary to generate a circulation in the rotor 22 of a current of an intensity equal to the first maximum intensity value l_rotor_max is determined, and the second maximum value max_C2 is transmitted to the heat engine 1.

[0099] An embodiment of sub-step E22 is illustrated by graph G2 shown in Figure 7. The x2 abscissa axis represents the temperature of the coolant in degrees Celsius. The y2 ordinate axis represents the operating mode of the alternator, which can be:

[0100] - according to mode M1 in which the rotor current limitation function is deactivated, or

[0101] - according to mode M2 ​​in which the rotor current limitation function is activated.

[0102] In substep E22, a temperature of the heat engine 1 is compared to a first temperature threshold S21 of the heat engine 1. Indeed, for the rotor current intensity limitation function to go from a deactivated state to an activated state, it is necessary for the temperature of the engine to be sufficiently high, in particular higher than the first temperature threshold S21 of the heat engine. In the embodiment illustrated by graph G2, the activation criterion of the limitation function relates to the temperature of a coolant of the heat engine and not to the temperature of the heat engine. For example, if the first temperature threshold S21 is set at 62 degrees Celsius, for the rotor current intensity limitation function to be able to be activated, it is necessary for the temperature of the coolant of the heat engine to be greater than or equal to 62 degrees Celsius.

[0103] An embodiment of sub-step E23 is illustrated by the graph G3 shown in Figure 8. The abscissa axis x3 represents the charge rate of the battery 3, expressed as a percentage. The ordinate axis y3 represents the operating mode of the alternator, which can be:

[0104] - according to mode M1 in which the rotor current limitation function is deactivated, or

[0105] - according to the mode M2 ​​in which the rotor current limitation function is activated. In the substep E23, a charge rate of the battery 3 is compared to a first charge threshold S31. In other words, for the rotor current intensity limitation function to go from a deactivated state to an activated state, it is necessary for a charge rate of the battery 3 to be sufficiently high, in particular greater than or equal to the first charge threshold S31. For example, if the first charge threshold S31 is set at 82%, for the rotor current intensity limitation function to be able to be activated, it is necessary for the charge rate of the battery 3 to be greater than 82%.

[0106] A mode of execution of step E2 can be described as follows.

[0107] In sub-step E21 we check that the motor torque is within a range of values ​​compatible with a limitation of the rotor current:

[0108] - if this is the case we continue with step E22,

[0109] - otherwise we do not limit the rotor current and we loop back to step E2.

[0110] In sub-step E22 we check that the motor temperature is within a range of values ​​compatible with a limitation of the rotor current:

[0111] - if this is the case we continue with step E23,

[0112] - otherwise we do not limit the rotor current and we loop back to step E2.

[0113] In sub-step E23 we check that the battery charge rate is within a range of values ​​compatible with a limitation of the rotor current:

[0114] - if this is the case, the control unit 5 transmits a message to the control module 101 to communicate to it a maximum engine torque value that the alternator is likely to take at most, without ever exceeding it, then we continue with step E3 to limit the rotor current to the first maximum intensity value l_rotor_max determined in step E21,

[0115] - otherwise we do not limit the rotor current and we loop back to step E2.

[0116] In the third step E3, the alternator 2 operates according to the second mode M2 ​​in which a second electric current produced by the alternator 2 supplies only the first electrical network 4, an intensity l_rotor of a third electric current circulating in the rotor 22 of the alternator 2 to produce the second electric current being less than the first maximum intensity value l_rotor_max.

[0117] In other words, in step E3, alternator 2 limits the intensity of the rotor current l_rotor to a maximum value l_rotor_max determined in step E21.

[0118] In addition, the third step E3 comprises an application by the alternator 2 of a second voltage U_2 to the terminals of the first network 4, the second voltage being less than or equal to the reference voltage U_ref of the battery, and, if the second voltage U_2 is strictly less than the reference voltage U_ref of the battery 3, then the third step comprises a supply, by the battery 3, of a fourth electric current supplying the first electrical network 4.

[0119] For this, in the third step E3, the controller 5 transmits to the alternator 2 a voltage command U_C_2 applicable to the network terminals.

[0120] The voltage command U_C_2 is defined so that a voltage U_2 of the current generated by the alternator 2 will be less than or equal to the battery reference voltage U_ref. The voltage U_2 of the current supplied by the alternator 2 being less than or equal to the battery reference voltage U_ref, the current from the alternator 2 is only used to supply the network 4. The battery 3 is then not recharged by the current from the alternator 2.

[0121] Furthermore, when the voltage U_2 is strictly lower than the voltage U_ref, then the battery 3 discharges to supply the network 4, in addition to the current supplied by the alternator 2.

[0122] Advantageously, the third step E3 comprises an implementation of a regulation loop between the voltage setpoint U_C_2 transmitted by the controller 5 to the alternator 2 and the voltage U_2 measured at the terminals of the network 4.

[0123] Following step E3, we then move on to a fourth step E4 of detecting the end of limitation of an intensity of a current produced by the alternator 2 comprising

[0124] - a sub-step E41 of comparing a current rotation speed of the heat engine with the first threshold S11 of rotation speed of the heat engine 1,

[0125] - a sub-step E42 of comparing a temperature of the heat engine 1 to a second threshold S22 of temperature of the heat engine 1,

[0126] - a sub-step E43 of comparing a current charge level of the battery 3 with a second battery charge threshold S32, and the second temperature threshold S22 of the heat engine 1 being strictly lower than the first temperature threshold S21 of the heat engine 1, and the second battery charge threshold S32 being strictly lower than the first battery charge threshold S31. In the sub-step E41, for the rotor current intensity limitation function to change from an activated state to a deactivated state, it is sufficient for the rotation speed of the engine to have increased so as to become greater than the first rotation speed threshold S11 of the heat engine 1.

[0127] An embodiment of sub-step E42 is illustrated by graph G2 shown in Figure 7.

[0128] In substep E42, a temperature of the heat engine 1 is compared to a second temperature threshold S22 of the heat engine 1. Indeed, for the rotor current intensity limitation function to change from an activated state to a deactivated state, it is sufficient for the temperature of the engine to have decreased so as to become lower than the second temperature threshold S22 of the heat engine. In the embodiment illustrated by graph G2, the criterion for deactivating the limitation function relates to the temperature of a coolant of the heat engine and not to the temperature of the heat engine. For example, if the second temperature threshold S22 is set at 60 degrees Celsius, the rotor current intensity limitation function can be deactivated because the temperature of the coolant of the heat engine has fallen below 60 degrees Celsius.

[0129] An embodiment of sub-step E42 is illustrated by graph G3 shown in Figure 8.

[0130] In substep E42, a charge rate of the battery 3 is compared to a second charge threshold S32. In other words, for the rotor current intensity limitation function to change from an activated state to a deactivated state, it is sufficient for a charge rate of the battery 3 to have decreased so as to become lower than the second charge threshold S32. For example, if the second charge threshold S32 is set at 80%, the rotor current intensity limitation function can be deactivated because the charge rate of the battery 3 has become lower than 80%.

[0131] Thus, thanks to the invention, the alternator is controlled to prevent it from producing more electricity than the car consumes at the current operating point of the motor vehicle. For example, if the car is idling, in a traffic jam, in summer and at altitude, the engine's capacities are reduced and it is preferable to limit the quantity of electric current produced by the alternator to simply cover the needs of the vehicle, i.e. the cooling of the engine and the thermal comfort of the vehicle's occupants. Thanks to the control method according to the invention, the remainder of the available engine torque can then be distributed to meet the vehicle's traction needs or the needs of a vehicle's air conditioning compressor.

[0132] In the invention, the limitation of the engine torque taken by the alternator is controlled by the limitation of the intensity of a current passing through the rotor, which is a parameter that is simpler to control than the engine torque taken by the alternator. In addition, the solution implemented in the invention includes a regulation of the voltage at the terminals of the network, which avoids fluctuations in the voltage supplying the vehicle's equipment.

[0133] The implementation of the limitation of the engine torque drawn by the alternator advantageously takes into account the state of charge of the battery, which provides more flexibility in the implementation of the limitation. For example, it is possible to tolerate an additional limitation of the torque drawn by the alternator if the battery is very well charged or for a limited duration, the battery then being able to be discharged to provide part of the current necessary for the operation of the network supplying the equipment. Such flexibility makes it possible, for example, to implement an anti-stall function for the engine when the engine speed falls much lower than the idle speed, or to allocate all the available torque to the vehicle's traction in the event of very strong acceleration.In these cases, it is possible to limit the intensity of the current passing through the rotor so as to produce only half of the electricity consumed by the network and to draw from the battery the additional electricity dedicated to supplying the network.

[0134] The invention also makes it possible to automatically detect when it is preferable to end the limitation of the engine torque dedicated to the alternator. For example, the end of a traffic jam is a typical situation for detecting deactivation of the limitation function. The engine no longer operates at idle and the engine speed increases. Since the alternator is no longer limited in its current production, it can then produce electrical energy greater than the car's consumption. The additional electrical energy makes it possible to recharge the battery if it has supplied current to the network during a previous limitation phase or if the battery is not yet fully charged.

[0135] Such an electrical energy management strategy, implemented thanks to the invention, increases the calibration possibilities during the development of the motor vehicle.

Claims

CLAIMS 1. Method for controlling an alternator (2) electrically connected to a battery (3) of a motor vehicle (100) and to a first electrical network (4) of the motor vehicle (100), characterized in that it comprises - a first step (E1) of operation of the alternator (2) according to a first mode (M1) in which a first electric current produced by the alternator (2) supplies the first electrical network (4), and the battery (3) for its recharging, - a second step (E2) of detecting a driving situation requiring limiting an intensity of a current flowing in a rotor (22) of the alternator (2) to a first maximum intensity value (l_rotor_max), then - a third step (E3) of operating the alternator (2) according to a second mode (M2) in which a second electric current produced by the alternator (2) supplies only the first electrical network (4), and in that an intensity (l_rotor) of a third electric current circulating in the rotor (22) of the alternator (2) to produce the second electric current is less than the first maximum intensity value (l_rotor_max).

2. Control method according to the preceding claim, characterized in that the first maximum intensity value (l_rotor_max) is determined as a function of a rotation speed of the heat engine (1).

3. Control method according to one of the preceding claims, characterized in that the first electrical network is a low voltage network, in particular a network whose voltage varies between 12V and 14V, or even between 12V and 15.6V, supplying a set of equipment of a motor vehicle, the set of equipment including an anti-lock braking system and / or a passenger compartment seat adjustment system and / or a lighting management system and / or a passenger compartment thermal comfort management system and / or a driving assistance system and / or multimedia systems.

4. Control method according to one of the preceding claims, characterized in that the first step (E1) and the third step (E3) implement a regulation loop between a voltage setpoint (U_C) transmitted to the alternator (2) and a voltage (U_A) measured at the terminals of the first electrical network (4).

5. Control method according to one of the preceding claims, characterized in that - the first step (E1) comprises an application by the alternator (2) of a first voltage (U_1) to the terminals of the first electrical network (4), the first voltage (U_1) being strictly greater than a reference voltage (U_ref) of the battery (3), the reference voltage of the battery (U_ref) corresponding to a voltage value causing neither charging nor discharging of the battery when it is applied to the terminals of the battery (3), and - the third step (E3) comprises an application by the alternator (2) of a second voltage (U_2) to the terminals of the first electrical network (4), the second voltage being less than or equal to the reference voltage (U_ref) of the battery, and - if the second voltage (U_2) is strictly lower than the reference voltage (U_ref) of the battery (3), then the third step (E3) comprises a supply, by the battery (3), of a fourth electric current supplying the first electrical network (4).

6. Control method according to one of the preceding claims, characterized in that the second step (E2) comprises a verification of conditions for applying a limitation of the intensity of the current flowing in the rotor of the alternator (2) comprising: - a sub-step (E21) of comparing a rotation speed of the heat engine (1) with a first threshold (S11) of rotation speed of the heat engine (1), and - a sub-step (E22) of comparing a temperature of the heat engine (1) with a first temperature threshold (S21) of the heat engine (1), and - a sub-step (E23) of comparing a charge level of the battery (3) with a first battery charge threshold (S31).

7. Control method according to the preceding claim, characterized in that the method further comprises a fourth step (E4) of detecting an end of limitation of an intensity of a current produced by the alternator (2) comprising - a sub-step (E41) of comparing a current rotation speed of the heat engine with the first threshold (S11) of rotation speed of the heat engine (1), - a sub-step (E42) of comparing a temperature of the heat engine (1) with a second temperature threshold (S22) of the heat engine (1), - a sub-step (E43) of comparing a current charge level of the battery (3) with a second charge threshold (S32) of the battery (3), and in that the second temperature threshold (S22) of the heat engine (1) is strictly lower than the first temperature threshold (S21) of the heat engine (1), and in that the second battery charge threshold (S32) is strictly lower than the first battery charge threshold (S31).

8. Control method according to one of the preceding claims, characterized in that the second step (E2) comprises a determination of a second maximum value of a motor torque necessary to generate a circulation in the rotor (22) of a current of an intensity equal to the first maximum intensity value (l_rotor_max), and a transmission of the second maximum value to the heat engine (1).

9. Device (10) for controlling an alternator (2) electrically connected to a battery (3) of a motor vehicle (100) and to a first electrical network (4) of the motor vehicle (100), the device comprising hardware and / or software elements (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 21, 22, 41, 42, 43, 44, 45, 46, 51, 52, 53, 61, 62, 63, 101, 102, 511, 512, 513, 514) implementing the method according to one of claims 1 to 8, in particular hardware elements (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 21, 22, 41, 42, 43, , 44, 45, 46, 51, 52, 53, 61, 62, 63, 101, 102) and / or software designed to implement the method according to one of the preceding claims.

10. Motor vehicle (100) equipped with a device (10) for controlling an alternator (2) according to the preceding claim.

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