EP4133567A1

EP4133567A1 - System for supplying electrical energy to a motor vehicle

Info

Publication number: EP4133567A1
Application number: EP21717054.7A
Authority: EP
Inventors: Julien JOUSSET; Gerard Saint-Leger
Original assignee: Renault SAS
Current assignee: Renault SAS
Priority date: 2020-04-10
Filing date: 2021-04-06
Publication date: 2023-02-15
Also published as: WO2021204806A1; FR3109248A1; FR3109248B1; CN115516733A

Abstract

This system for supplying (2) electrical energy to a motor vehicle comprises a grid (4), a first battery (8) connected to the grid (4) and having a first maximum no-load voltage, a second battery (10) connected to the grid (4) and having a second maximum no-load voltage strictly greater than the first maximum no-load voltage, a controllable alternator (6) connected to the grid (4) and capable of delivering an electrical energy, an electronic management unit (12) controlling a voltage of the electrical energy delivered by the alternator (6) during travel of the vehicle. The electronic management unit (12) successively imposes a first setpoint voltage strictly between the maximum no-load voltages, a second setpoint voltage strictly between the first maximum no-load voltage and the first setpoint voltage and a third setpoint voltage strictly less than the first maximum no-load voltage.

Description

Electric power supply system of a motor vehicle

The present application relates to a system and a method for supplying electric power to a motor vehicle comprising a dual network, in particular for micro-hybrid motor vehicles.

In the automotive field, a dual network comprises at least two electrical storage batteries. Such a network can in particular be used by specializing the role of each of the batteries.

In a typical example, a dual network includes an on-board network battery providing power to the network when the engine and alternator are not operating. An energy recovery battery charges when the operating point of the engine and the vehicle is favorable and discharges, for example, when the vehicle is moving at a steady speed or accelerating.

Reference may for example be made to the patent granted FR 2 975 839 which describes such an example of a dual network.

Although such a network is generally satisfactory, it happens that, when the onboard network battery is not correctly charged, it imposes a recharging voltage on the alternator, which prevents the discharge of the recovery battery. of energy. This results, in particular for vehicles with hybrid or micro hybrid propulsion, in less fuel consumption for the vehicle.

The invention aims to remedy these drawbacks.

More particularly, the invention aims to allow the electric power supply of a vehicle by a dual network, by limiting the loss of gain in consumption of the vehicle.

To this end, there is proposed a system for supplying electrical energy to a motor vehicle, comprising a network of at least one electrical consumer unit, a first electrical storage battery connected to the network and having a first maximum voltage at empty, a second electric storage battery connected to the network and having a second maximum no-load voltage strictly greater than the first maximum voltage off-load, a controllable alternator connected to the network and able to deliver electrical energy, and an electronic management unit able to control a voltage supplied by the alternator when the vehicle is running.

According to a general characteristic of this system, the electronic management unit is configured to impose on the alternator successively, while the vehicle is being driven, a first setpoint voltage strictly between the first maximum no-load voltage and the second maximum voltage. no-load, a second setpoint voltage strictly between the first maximum no-load voltage and the first setpoint voltage and a third setpoint voltage strictly lower than the first maximum no-load voltage.

Such control of the voltage delivered by the alternator using the aforementioned setpoint voltages makes it possible to delay the recharging of the first battery, which avoids encountering difficulties in draining the second battery and therefore losing the gain in consumption of the vehicle. .

In one embodiment, the electronic management unit comprises a map delivering voltage values as a function of a state of charge of the first battery, the electronic management unit being configured to impose, while the vehicle is being driven. , the voltage value delivered by the mapping.

Provision can also be made for the mapping to deliver the first setpoint voltage if the state of charge of the first battery is less than or equal to a first threshold and the mapping to deliver the third setpoint voltage if the state of charge of the first battery. battery is greater than or equal to a second threshold, the second threshold being strictly greater than the first threshold.

According to one embodiment, the first threshold is between 83.5% and 84.5%. According to another embodiment, the second threshold is between 90% and 92%.

Provision can also be made for the mapping to deliver the second setpoint voltage if the state of charge of the first battery is between a third threshold and a fourth threshold, the third threshold. being greater than or equal to the first threshold, the fourth threshold being strictly greater than the third threshold and less than or equal to the second threshold.

In one embodiment, the third threshold is between 84.5% to 85.5%.

Preferably, the fourth threshold is between 88% and 90%.

Advantageously, the electronic management unit is configured to impose, if the motor vehicle is going through an energy recovery phase, a fourth setpoint voltage that is strictly greater than the first setpoint voltage.

Advantageously, the first setpoint voltage is calculated as the product of the second maximum no-load voltage by a first coefficient between 0.8 and 0.99.

Provision can also be made to calculate the third setpoint voltage as the product of the first maximum no-load voltage by a second coefficient between 0.8 and 0.99.

In another embodiment, the second setpoint voltage is calculated as the product of the first maximum no-load voltage by a factor between 1.01 and 1.1. According to another aspect, a supply method is provided. in electrical energy of a motor vehicle by means of a system as defined above, in which the electronic control unit successively imposes on the alternator, during the running of the vehicle, the first setpoint voltage, the second voltage setpoint and the third setpoint voltage.

Other objects, characteristics and advantages of the invention will become apparent on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which: [FIG. 1] diagrammatically represents a system according to a aspect of the invention,

[fig 2] is a graph illustrating a map of the system of figure 1, [fig 3] schematically illustrates the system of figure 1 operating according to a first operating mode,

[fig 4] schematically illustrates the system, the system of figure 1 operating according to a second operating mode, [fig 5] schematically illustrates the system of figure 1 operating according to a third operating mode,

[fig 6] schematically illustrates the system of figure 1 operating according to a fourth operating mode, and

[Fig 7] schematically illustrates a method according to another aspect of the invention.

Referring to Figure 1, there is schematically shown an electric power supply system 2. The system 2 is intended to be incorporated into a motor vehicle (not referenced), in this case a micro-hybrid vehicle. System 2 comprises an electrical network 4 and a fuse 5. System 2 comprises an alternator 6 connected to network 4 via fuse 5. Alternator 6 is used to convert the mechanical energy taken from a shaft connected to a motor. thermal (not shown) into electrical energy sent to network 4. System 2 comprises an on-board network battery 8 connected to network 4 via fuse 5. System 2 comprises an energy recovery battery 10 connected to network 4 via fuse 5.

The network 4 comprises a plurality of electrical consumer units, in this case an air conditioning device 14, lighting means 16 and heating means 18. It is not beyond the scope of the invention to envisage consuming units. different electrics.

In the example illustrated, the battery 8 is a lead acid battery. The battery 8 has a maximum no- _load voltage V batt s _max and a minimum no- _load voltage V batt s _min .

Battery 10 is a lithium-ion type battery. The battery 10 has a maximum no-load voltage Vbatt i omax and a minimum no-load voltage Vbatt i omin. The voltage Vbatt i omax is strictly greater than the voltage Vbatt8max [Math 1]

^ battlOmax ^ battSmax

In this case, the voltage Vbatt i omax is equal to 16 V and the voltage Vbattsmax is equal to 12.8 V. More specifically, the no-load voltage characteristic of battery 8 is shown in Table 1 below. [Table 1]

The no-load voltage characteristic of battery 10 is shown in Table 2 below. [Table 21

The alternator 6 can be controlled. More particularly, the voltage Tait of the electrical energy delivered by the alternator 6 can be imposed. The system 2 comprises an electronic management unit 12. The electronic management unit 12 is capable of controlling the voltage Tait when the vehicle is moving. To do this, the electronic management unit 12 is configured to take into account the state of charge SOCs of the battery 8. In this regard, the electronic management unit 12 comprises a map 20 illustrated by the graph in FIG. 2.

Referring to Figure 2, the mapping 20 includes a tension T values _is based on the SOCs charge state. T _is the voltage delivered by the mapping 20 corresponds to the voltage imposed by the electronic control unit 12 to the alternator 6.

The map 20 comprises a first zone 22 corresponding to a state of charge SOCs below a threshold S i. In this case, the threshold S i is between 83.5% and 84.5% and substantially equal to 84%. When state of charge SOCs is within the area 22, the tension T _is delivered by the mapping 20 is a strictly TCi reference voltage between the voltage V _batt s _max and the voltage

Vbatt l Omax

[Math 2] Vbatt8max ^ TC i <VbattlOmax

In the example illustrated, the voltage TCi is substantially equal to

14.5 V.

There is schematically shown in Figure 3 an operating diagram of the system 2 when the map 20 delivers the voltage TCi for the value of T _ait In this case, the vehicle is rolling and the alternator 6 delivers electrical energy at voltage TCi as represented by arrow 24.

This electrical energy supplies the network 4 as illustrated by the arrow 26. The relatively high setpoint voltage TCi makes it possible to recharge the battery 8 as illustrated by the arrow 28. Moreover, this voltage almost completely reduces the possibility of restoring energy from battery 10, which operates most of the time on charge, as illustrated by arrow 30.

Thus, zone 22 corresponds to a mode of recharging the on-board network battery 8 aimed at increasing the state of charge SOCs even if it means reducing the possibility of restoring energy by the battery 10.

Again with reference to FIG. 2, the graph illustrating the map 20 comprises a second zone 32 corresponding to a state of charge SOCs greater than or equal to a threshold S2 strictly greater than threshold S i. In this case, the threshold S2 is between 90% and 92%. In zone 32, the map 20 delivers a voltage TC2 strictly lower than the voltage Vbattsmax:

[Math 3] TC 2 <Vbatt8max

In this case, the voltage TC2 is substantially equal to 12.6 V.

The operating case corresponding to zone 32 has been schematically represented in FIG. 4. In this case, the vehicle is traveling and the state of charge SOCs is relatively high. The alternator 6 delivers electrical energy as shown diagrammatically by the arrow 34, at the voltage TC2 lower than in the case of operation corresponding to FIG. 3.

Due to the relatively low voltage TC2, the battery 8 is forced to give back energy as illustrated by arrow 36. Likewise, the battery 10 is forced, most of the time, to give back energy as. illustrated by the arrow 38. The energy delivered by the alternator 6, the battery 8 and the battery 10 is transmitted to the network 4 as illustrated by the arrow 40.

Thus, zone 32 corresponds to an energy return mode in which the electrical energy supplied to the network 4 is notably delivered by the battery 10 and by the alternator 6, and possibly by the battery 8.

Again with reference to FIG. 2, the graph illustrating the map 20 comprises a third zone 42 extending between thresholds S3 and S4. The thresholds S i, S3, S4 and S2 follow each other in this order on the x-axis of the graph of figure 2. In other words, we have:

[Math 4]

If <S ₃ <S ₄ <S 2

In this case, the threshold S ₃ is between 84.5% and 85.5% and the threshold S ₄ is between 88% and 90%.

In zone 42, the map 20 delivers a voltage Tait equal to a reference voltage TC ₃ .

The voltage TC3 is strictly between the voltage Vbattsmax and the voltage TCi: [Math 5]

Vbatt8max TC ₃ <TC ₁

In this case, the voltage TC3 is substantially equal to 13 V.

With reference to FIG. 5, the operating case corresponding to zone 42 has been schematically represented. In this case, the vehicle is traveling without an energy recovery phase and the state of charge SOCs is slightly less than 90%. The alternator 6 delivers electrical energy to the voltage TC3 as illustrated by the arrow 44.

Due to the voltage TC3 slightly higher than the voltage V _{batt 8max} , the battery 8 is neither charged nor discharged. In fact, when TC3 is given a typical value of 13 volts, this is what is called in the technical literature the “floating” voltage, that is to say charge maintenance.

The difference between 13 volts and 12.8 volts, minus losses of all kinds (electrochemical, resistive, etc.) does not allow a charge current greater than a few hundred mA to be reached. This means that when we tend the voltage TC3 to 13 volts for a SOC calculated at 90%, we will in practice stop at this value of 90%. In theory, it would take several hours to keep raising the SOCs. For example, if we reached 1 ampere, it would take 7 hours to go from 90 to 100%. In practice, a current is often observed very close to 0A, when driving on a motorway for a good hour, when the battery has reached 90%, and the calculated SOCs no longer move.

On the other hand, taking into account the setpoint voltage TC3 markedly lower than the voltage Vbatt i omax, the restitution of energy by the battery 10 is authorized as illustrated by the arrow 46, however to a lesser extent than in the case of operation. of FIG. 4. The electrical energy delivered by the alternator 6 and the battery 10 is transmitted to the network 4 as illustrated by the arrow 48.

Thus, in this case of operation, the electronic management unit 12 forces the system 2 into a limited energy return mode in which the energy return by the battery 10 is allowed within a certain limit, in order to avoid charging and discharging the battery 8.

Again with reference to FIG. 2, the graph illustrating the cartography 20 comprises a transient zone 50 situated between zones 22 and 42 and a transient zone 52 situated between zones 42 and 32.

In other words, zone 50 corresponds to a state of charge SOCs between S i and S3. Zone 52 corresponds to a state of charge between S ₄ and S ₂ .

In zone 50, the curve Tait = f (SOCs) forms a linear interpolation between zones 22 and 42. In zone 52, the curve T _a it = f (SOCs) forms a linear interpolation between zones 42 and 32. We do not depart from the scope of the invention by considering an interpolation of a different order, or even by considering another transition between the zones 22, 42 and 32. Whatever the value of the state of charge SOCs, the mapping 20 delivers a setpoint voltage TC ₄ if the motor vehicle is going through an energy recovery phase. The voltage TC ₄ is strictly greater than the voltage TCi and strictly less than a maximum voltage V _max of network 4: [Math 6]

TC _t <TC ₄ <V _max

To determine whether the motor vehicle is going through an energy recovery phase, the electronic management unit 12 may for example include a means of receiving the instruction at the vehicle pedal. The electronic management unit 12 can therefore detect an engine deceleration phase and deduce that the vehicle is going through an energy recovery phase.

With reference to FIG. 6, the operating case corresponding to an energy recovery phase has been schematically illustrated. In this case, the vehicle is moving and is going through an energy recovery phase. Alternator 6 delivers electrical energy to voltage TC ₄ as illustrated by arrow 50.

Given the high value of voltage TC ₄ , batteries 8 and 10 are forced into recharging mode as illustrated by arrows 52 and 54. Electrical energy supplied by the alternator 6 is also sent to the network 4 as illustrated by the arrow 56.

In this case, the electronic management unit 12 forces the system 2 into energy recovery mode in which the energy supplied by the alternator 6 is sent to the network 4, the rest being stored in the batteries 8 and 10.

With reference to FIG. 7, there is schematically illustrated an electrical supply method according to another aspect of the invention.

The method comprises a first initialization step E01 which can be implemented periodically, for example every tenth of a second while the vehicle is being driven.

The method comprises a second step E02 in which it is determined whether the vehicle is going through a recovery phase.

If the response of step E02 is “YES”, a step E03 is applied during which the voltage Tait is set equal to TC4.

If the response of step E02 is “NO”, a step E04 of calculating the state of charge SOCs is implemented.

Then implements a step E05 of calculating the tension T _is determined corresponding to the load condition during the step E04. To do this, one can use the map 20 schematically shown in Figure 2.

At the end of step E03 or of step E05, a step E06 of controlling the alternator 6 is implemented by imposing the voltage of the electrical energy delivered by the alternator 6 equal to the voltage T _is determined during step E03 or E05. This results in forcing of the system 2 in one of the operating cases exposed with reference to FIGS. 3 to 6. At the end of step E06, the process is terminated.

By virtue of this method, the state of charge SOCs of the on-board network battery 8 must naturally converge towards 90%. Indeed, the recovery phases detailed with reference to FIG. 6 will recharge the battery 8 without letting it discharge as long as the state of charge SOCs is less than 90%. If the state of charge SOCs exceeds 90%, the battery 8 contributes to the discharge phases, due to the reduction of the tension T _is delivered by the alternator 6. Such an operation makes it possible, starting from an average state of charge at 90%, to keep all the performance of the energy recovery battery 10, even if the on-board network battery 8 is called upon between two missions of the vehicle. In fact, in certain phases, such as parking, the energy recovery battery 10 is not available because its capacity does not allow it to supply power to all the electronic systems of the vehicle. This power supply function may drop the state of charge of the onboard power supply battery 8 below 90%. If the SOCs state of charge remains satisfactory, in this case greater than 85%, the power supply system 2 will be practically completely operational and the on-board network battery 8 will be charged in the recovery phases without preventing the essential phases of discharge of the energy recovery battery 10. If, on the contrary, the state of charge SOCs drops too low, we will go to a forced charging phase as long as the state of charge SOCs has not gone below. above the 85% threshold.

It is possible, without departing from the scope of the invention, to envisage setpoint voltages different from the aforementioned values. Preferably, the setpoint voltage TCi is calculated as the product of the voltage Vbatt i omax by a coefficient between 0.8 and 0.99. Likewise, the voltage TC ₂ is calculated as the product of the voltage Vbattsmax by a coefficient between 0.8 and 0.99. The voltage TC ₃ is calculated as the product of the voltage Vbattsmax by a factor between 1.01 and 1.1.

Such ranges of values make it possible to make the state of charge of the battery 8 converge towards a relatively high state of charge, while making it possible to easily force the power supply system 2 into energy return and limited energy return mode. . This results in the possibility of optimally timing the recharging of the on-board network battery 8 and therefore of maximizing the gain in consumption of the vehicle.

Claims

1. System (2) for supplying electrical energy to a motor vehicle, comprising a network (4) of at least one member (14, 16, 18) which consumes an electrical power, a first battery (8) for electrical storage. connected to the network (4) and having a first maximum no-load voltage, a second electric storage battery (10) connected to the network (4) and having a second maximum no-load voltage strictly greater than the first maximum no-load voltage, a controllable alternator (6) connected to the network (4) and able to deliver electrical energy, and an electronic management unit (12) able to control a voltage (Tait) supplied by the alternator (6) when the vehicle is moving, characterized in that, when the vehicle is not in the energy recovery phase, the electronic management unit (12) is configured to impose on the alternator (6) successively, during the travel of the vehicle, in depending on the state of charge of the first battery (8) of a electrical accumulation, a first setpoint voltage (TCi) strictly between the first maximum no-load voltage and the second maximum no-load voltage, a second set-point voltage (TC ₃ ) strictly between the first maximum no-load voltage and the first voltage setpoint (TCi) and a third setpoint voltage (TC ₂ ) strictly lower than the first maximum no-load voltage.

2. System (2) according to claim 1, wherein the electronic management unit (12) comprises a map (20) delivering voltage values (Tait) as a function of a state of charge (SOCs) of the first. battery (8), the electronic management unit (12) being configured to impose, during the travel of the vehicle, the voltage value (T _a it) delivered by the map (20).

3. System (2) according to claim 2, wherein the mapping (20) delivers the first setpoint voltage (TCi) if the state of charge (SOCs) of the first battery is less than or equal to a first threshold (S i) and the mapping (20) delivers the third setpoint voltage (TC2) if the state of charge (SOCs) of the first battery (8) is greater than or equal to a second threshold (S2), the second threshold (S2) being strictly greater than the first threshold (S i).

4. System (2) according to claim 3, wherein the first threshold (S i) is between 83.5% and 84.5% and / or the second threshold (S2) is between 90% and 92%.

5. System (2) according to claim 3 or 4, wherein the mapping (20) delivers the second setpoint voltage (TC3) if the state of charge (SOCs) of the first battery (8) is between a third threshold (S3) and a fourth threshold (S4), the third threshold (S3) being greater than or equal to the first threshold (S i), the fourth threshold (S4) being strictly greater than the third threshold (S3) and less than or equal to second threshold (S2).

6. System (2) according to claim 5, wherein the third threshold (S3) is between 84.5% and 85.5% and / or the fourth threshold (S4) is between 88% and 90%.

7. System (2) according to any one of claims 1 to 6, wherein the electronic management unit (12) is configured to impose, if the motor vehicle passes through an energy recovery phase, a fourth voltage of. setpoint (TC4) strictly greater than the first setpoint voltage (TCi).

8. System (2) according to any one of claims 1 to 7, wherein the first setpoint voltage (TCi) is calculated as the product of the second maximum no-load voltage by a first coefficient and / or the third voltage of. setpoint (TC2) is calculated as the product of the first maximum no-load voltage by a second coefficient, the first and second coefficients being between 0.8 and 0.99.

9. System (2) according to any one of claims 1 to 8, wherein the second setpoint voltage (TC3) is calculated as the product of the first maximum no-load voltage by a factor between 1.01 and 1, 1.

10. A method of supplying electrical energy to a motor vehicle by means of a system (2) according to any one of claims 1 to 9, wherein the electronic management unit (12) imposes on the alternator (6) successively, during travel of the vehicle, the first setpoint voltage (TCi), the second setpoint voltage (TC2) and the third setpoint voltage (TC3).