CN115516733A

CN115516733A - System for supplying motor vehicle with electrical energy

Info

Publication number: CN115516733A
Application number: CN202180033805.4A
Authority: CN
Inventors: J·茹塞; G·圣-莱格尔
Original assignee: Renault SAS
Current assignee: Renault SAS
Priority date: 2020-04-10
Filing date: 2021-04-06
Publication date: 2022-12-23
Also published as: EP4133567A1; FR3109248B1; FR3109248A1; WO2021204806A1

Abstract

A system (2) for supplying electric energy to a motor vehicle comprises: a network (4); a first accumulator (8) connected to the network (4) and having a first maximum no-load voltage; a second accumulator (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 capable of delivering electrical energy; an electronic management unit (12) which controls the voltage of the electrical energy delivered by the alternator (6) during the travel of the vehicle. The electronic management unit (12) successively applies a first setpoint voltage strictly between the two 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

System for supplying motor vehicle with electrical energy

Technical Field

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

Background

In the motor vehicle sector, a dual network comprises at least two batteries. Such a network can be used, among other things, by specifying the role of each battery.

In a typical example, the dual network includes an onboard network battery that ensures the network power supply when the engine and alternator are not operating. The energy harvesting battery is charged when the operating point of the engine and vehicle is favorable and discharged, for example, when the vehicle is traveling at a steady or accelerated speed.

For example, reference may be made to the issued patent FR 2 975 839, which describes such an example of a dual network.

While such networks are generally satisfactory, it is possible that when an on-board network battery is not properly charged, the battery will apply a recharging voltage to the alternator, which prevents discharge of the energy harvesting battery. Especially for hybrid or micro-hybrid propelled vehicles, the result is that vehicle consumption savings will be less.

Disclosure of Invention

The aim of the invention is to remedy these drawbacks.

More specifically, the aim of the invention is to allow the vehicle to be powered by the dual network by limiting the vehicle consumption saving losses.

To this end, a system for supplying electric energy to a motor vehicle is proposed, comprising: a network having at least one power consuming component; a first battery connected to the network and having a first maximum no-load voltage; a second battery connected to the network and having a second maximum no-load voltage strictly greater than the first maximum no-load voltage; a controllable alternator connected to the network and capable of delivering electrical energy; and an electronic management unit capable of driving the voltage delivered by the alternator while the vehicle is running.

According to a general characteristic of this system, the electronic management unit is configured to apply to the alternator, while the vehicle is running, successively a first setpoint voltage strictly between the first maximum no-load voltage and the second maximum no-load voltage, 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.

This control of the voltage delivered by the alternator by using the above-mentioned setpoint voltage makes it possible to delay the recharging of the first battery, which avoids encountering difficulties in depleting the second battery and therefore avoids losing vehicle consumption savings.

In one embodiment, the electronic management unit comprises a map delivering voltage values according to the state of charge of the first battery, the electronic management unit being configured to apply the voltage values delivered by the map while the vehicle is driving.

It may also be provided that the map delivers the first set point voltage if the state of charge of the first battery is lower than or equal to a first threshold value, and delivers the third set point voltage if the state of charge of the first battery is higher than or equal to a second threshold value, which is strictly higher than the first threshold value.

According to an embodiment, the first threshold is between 83.5% and 84.5%.

According to a further embodiment, the second threshold is between 90% and 92%.

It may also be provided that the map delivers the second setpoint voltage if the state of charge of the first battery is between a third threshold value, which is higher than or equal to the first threshold value, and a fourth threshold value, which is strictly higher than the third threshold value and lower than or equal to the second threshold value.

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

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

Advantageously, the electronic management unit is configured to apply a fourth setpoint voltage strictly greater than the first setpoint voltage when the motor vehicle undergoes an energy harvesting phase.

Advantageously, the first setpoint voltage is calculated as the product of the second maximum open-load voltage multiplied by a first factor between 0.8 and 0.99.

It may also be provided that the third set point voltage is calculated as the product of the first maximum float voltage multiplied by a second factor between 0.8 and 0.99.

In another embodiment, the second set point voltage is calculated as the product of the first maximum open load voltage multiplied by a factor between 1.01 and 1.1.

According to another aspect, a method is proposed for supplying electric energy to a motor vehicle by means of a system as defined previously, in which the electronic management unit applies to the alternator, while the vehicle is running, the first setpoint voltage, the second setpoint voltage and the third setpoint voltage in succession.

Drawings

Other objects, features and advantages of the present invention will become apparent from a reading of the following description, given purely by way of non-limiting example and with reference to the accompanying drawings, in which:

figure 1 schematically shows a system according to an aspect of the invention,

figure 2 is a diagram illustrating a mapping of the system of figure 1,

figure 3 schematically illustrates the operation of the system of figure 1 according to a first mode of operation,

figure 4 schematically illustrates the operation of the system of figure 1 according to a second mode of operation,

figure 5 schematically illustrates the operation of the system of figure 1 according to a third mode of operation,

FIG. 6 schematically illustrates the operation of the system of FIG. 1 according to a fourth mode of operation, an

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

Detailed Description

Referring to fig. 1, a power supply system 2 is schematically shown. The system 2 is intended to be incorporated in a motor vehicle (not referenced), in this particular case a micro-hybrid vehicle.

The system 2 includes an electrical network 4 and a fuse 5. The system 2 comprises an alternator 6 connected to the network 4 via a fuse 5. The alternator 6 is intended to convert the mechanical energy obtained from a shaft linked to a heat engine (not represented) into electrical energy sent to the network 4. The system 2 includes an onboard network battery 8 that is connected to the network 4 via a fuse 5. The system 2 comprises an energy harvesting battery 10 connected to the network 4 via a fuse 5.

The network 4 comprises a plurality of power consuming components, in this case air conditioning equipment 14, lighting devices 16 and heating devices 18. When different power consuming components are envisaged, without departing from the scope of the invention.

In the illustrated example, the battery 8 is a lead-acid battery. The battery 8 having a maximum no-load voltage V _batt8max And minimum no-load voltage V _batt8min 。

The battery 10 may be a lithium ion type battery. The battery 10 has a maximum no-load voltage V _batt10max And minimum no-load voltage V _batt10min . Voltage V _batt10max Strictly greater than voltage V _batt8max ：

[ mathematical formula 1]

V _batt10max ＞V _batt8max

In this case, the voltage V _batt10max Equal to 16V and voltage V _batt8max Equal to 12.8V.

More specifically, the no-load voltage characteristics of the battery 8 are shown in table 1 below.

[ Table 1]

OCV(V)	SOC
		12.5	70％
12.6	80％
		12.62	82％
12.67	87％
		12.7	90％
12.73	93％
		12.8	100％

The no-load voltage characteristics of the battery 10 are shown in table 2 below.

[ Table 2]

OCV(V)	SOC
		13.0	50％
13.5	59％
		14.0	68％
14.5	77％
		15.0	86％
15.5	95％
		16.0	100％

The alternator 6 is controllable. More specifically, it is possible to apply a voltage T of electrical energy delivered by the alternator 6 _alt 。

The system 2 comprises an electronic management unit 12. The electronic management unit 12 is able to control the voltage T while the vehicle is running _alt . For this purpose, an electronic management sheetThe cell 12 is configured to determine the state of charge SOC of the battery 8 ₈ Taking this into account. In this regard, the electronic management unit 12 includes a map 20 illustrated by the diagram in fig. 2.

Referring to FIG. 2, the map 20 includes as the state of charge SOC ₈ Voltage T of function of _alt The value of (c). The voltage T delivered by the map 20 _alt Corresponding to the voltage applied by the electronic management unit 12 to the alternator 6.

The map 20 includes a first region 22 corresponding to being below a threshold S ₁ State of charge SOC of ₈ . In this case, the threshold S ₁ Between 83.5% and 84.5% and substantially equal to 84%. When state of charge SOC ₈ The voltage T delivered by the map 20 when located within the region 22 _alt Is a setpoint voltage TC ₁ The setpoint voltage being strictly between the voltages V _batt8max And a voltage V _batt10max The method comprises the following steps:

[ mathematical formula 2]

V _batt8max ＜TC ₁ ＜V _batt10max

In the illustrated example, the voltage TC ₁ Substantially equal to 14.5V.

Fig. 3 schematically shows when the map 20 delivers a voltage TC ₁ As T _alt The value of (c) is an operation diagram of the system 2. In this case, the vehicle is running, and the alternator 6 is at the voltage TC ₁ Electrical energy is delivered as represented by arrow 24.

This power powers the network 4 as shown by arrow 26. Relatively high setpoint voltage TC ₁ So that the battery 8 can be recharged as illustrated by arrow 28. Furthermore, this voltage almost completely reduces the possibility of recovering energy from the battery 10, which will operate in a charging mode most of the time, as illustrated by arrow 30.

Thus, the region 22 corresponds to the on-board network battery 8 recharging mode, the goal of which is to increase the state of charge SOC ₈ Even if this means that the possibility of energy recovery by the battery 10 is reduced.

Referring again to FIG. 2, there is shownThe map of the map 20 comprises a second region 32 corresponding to being higher than or equal to the threshold S ₂ State of charge SOC of ₈ The threshold value is strictly higher than the threshold value S ₁ . In this case, the threshold S ₂ Between 90% and 92%. In region 32, map 20 delivers a voltage TC ₂ The voltage is strictly less than the voltage V _batt8max ：

[ mathematical formula 3]

TC ₂ ＜V _batt8max

In this case, the voltage TC ₂ Substantially equal to 12.6V.

Fig. 4 schematically shows the operation corresponding to the region 32. In this case, the vehicle is running, and the state of charge SOC ₈ Is relatively high. The alternator 6 is represented schematically by the arrow 34 with a voltage TC ₂ Electrical energy is delivered, the voltage being lower than in the operating situation corresponding to fig. 3.

Due to voltage TC ₂ Relatively low and the battery 8 is therefore forced to perform energy recovery, as illustrated by arrow 36. Likewise, the battery 10 is forced to perform energy recovery most of the time, as illustrated by arrow 38. The energy delivered by alternator 6, battery 8 and battery 10 is transmitted to network 4 as illustrated by arrow 40.

Thus, the area 32 corresponds to an energy recovery mode in which the electrical energy supplied to the network 4 is delivered by, among other things, the battery 10 and the alternator 6, and possibly by the battery 8.

Referring again to FIG. 2, a graph showing the mapping 20 included at the threshold S ₃ And S ₄ A third region 42 extending therebetween. Threshold value S ₁ 、S ₃ 、S ₄ And S ₂ Arranged one after the other in this order along the x-axis of the diagram in fig. 2. In other words:

[ mathematical formula 4]

S ₁ ＜S ₃ ＜S ₄ ＜S ₂

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

In region 42, map 20 delivers a voltage equal to the set point voltage TC ₃ Voltage T of _alt 。

Voltage TC ₃ Strictly between voltages V _batt8max And voltage TC ₁ The method comprises the following steps:

[ mathematical formula 5]

V _batt8max ＜TC ₃ ＜TC ₁

In this case, the voltage TC ₃ Substantially equal to 13V.

Referring to fig. 5, the operation corresponding to region 42 is schematically illustrated. In this case, the vehicle is running and not in the energy harvesting phase, and the state of charge SOC ₈ Slightly below 90%. Alternator 6 at voltage TC ₃ Electrical energy is delivered as illustrated by arrow 44.

Due to voltage TC ₃ Slightly greater than voltage V _batt8max And therefore the battery 8 is neither charged nor discharged. In fact, when TC occurs ₃ Given a typical value of 13 volts, this is known in the art as the "floating" voltage, that is to say the charge sustaining voltage.

The difference between 13 volts and 12.8 volts is reduced by various losses (electrochemical loss, resistance loss, etc.), which cannot achieve a charging current greater than several hundred mA, which means when the voltage TC is made ₃ Trending toward 13 volts to calculate 90% SOC ₈ In practice it will stop at this 90% value.

Theoretically, the SOC continues to increase ₈ It will take several hours. For example, if 1 ampere is reached, it will take 7 hours from 90% to 100%. In practice, when the battery has reached 90% and the calculated SOC ₈ When no longer moving, the current observed in the morning when driving on an expressway is typically very close to 0A.

On the other hand, taking into account the setpoint voltage TC ₃ Significantly lower than voltage V _batt10max Battery 10 is permitted to recover energy, as illustrated by arrow 46, but to a lesser extent than in the operating case of fig. 4. The electric energy delivered by the alternator 6 and the battery 10 is transmitted to the network 4, such as an arrowAs shown in head 48.

In this operating situation, therefore, the electronic management unit 12 forces the system 2 to enter a limited energy recovery mode in which the battery 10 is permitted to perform energy recovery within certain limits, so as to avoid charging and discharging of the battery 8.

Referring again to fig. 2, the map showing the map 20 includes a transition region 50 between the

regions

22 and 42 and a transition region 52 between the

regions

42 and 32. In other words, region 50 corresponds to a value between S ₁ And S ₃ State of charge SOC in between ₈ . Region 52 corresponds to the interval S ₄ And S ₂ To a state of charge in between.

In the region 50, the curve T _alt ＝f(SOC ₈ ) A linear interpolation is formed between

regions

22 and 42. In the region 52, the curve T _alt ＝f(SOC ₈ ) A linear interpolation is formed between

regions

42 and 32. It would not depart from the scope of the present invention by envisaging a different sequence of interpolations or even by envisaging another transition between the

regions

22, 42 and 32.

Regardless of the state of charge SOC ₈ Is, map 20 delivers a setpoint voltage TC as the motor vehicle undergoes an energy harvesting phase ₄ . Voltage TC ₄ Strictly greater than voltage TC ₁ And strictly less than the maximum voltage V of the network 4 _max ：

[ mathematical formula 6]

TC ₁ ＜TC ₄ ＜V _max

In order to determine whether the motor vehicle is undergoing an energy harvesting phase, electronic management unit 12 may, for example, comprise means for receiving a setpoint at a pedal of the vehicle. Thus, electronic management unit 12 may detect the engine deceleration phase and infer therefrom that the vehicle is undergoing the energy harvesting phase.

Referring to fig. 6, the operating conditions corresponding to the energy harvesting phase are schematically illustrated. In this case, the vehicle is traveling and undergoing an energy harvesting phase. Alternator 6 at voltage TC ₄ Electrical energy is delivered as illustrated by arrow 50.

Taking into account the voltage TC ₄ Value of (A)Higher, the

batteries

8 and 10 are forced into a recharge mode, as illustrated by

arrows

52 and 54. Furthermore, the electrical energy supplied by the alternator 6 is sent to the network 4, as illustrated by arrow 56.

In this case, the electronic management unit 12 forces the system 2 into an energy harvesting mode, in which the energy supplied by the alternator 6 is sent to the network 4, the remaining energy being stored in the

batteries

8 and 10.

Referring to fig. 7, a power supply method according to another aspect of the present invention is schematically illustrated.

The method comprises a first initialization step E01, which may be carried out periodically (for example, every tenth of a second) while the vehicle is running.

The method comprises a second step E02, in which it is determined whether the vehicle is undergoing a collection phase.

If the response of step E02 is "YES", a step E03 is applied, in which the voltage T is applied _alt Is set equal to TC ₄ 。

If the response of step E02 is "NO", then a calculation of the state of charge SOC is carried out ₈ Step E04 of (a).

Then, step E05 is carried out, i.e. the voltage T corresponding to the state of charge determined during step E04 is calculated _alt . For this purpose a mapping 20 as schematically represented in fig. 2 may be used.

At the end of step E03 or step E05, step E06 is carried out to control alternator 6 by applying a voltage of electrical energy supplied by alternator 6 equal to voltage T determined during step E03 or E05 _alt . As a result of which the system 2 is forced into one of the operating situations explained with reference to fig. 3 to 6. At the end of step E06, the method is terminated.

By means of the method, the SOC of the on-board network battery 8 ₈ It should naturally converge towards 90%. In practice, as long as the state of charge SOC is present ₈ Below 90%, the harvesting phase, described in detail with reference to fig. 6, will recharge the battery 8 without allowing it to discharge. If state of charge SOC ₈ Over 90%, the reason is thatThe voltage T delivered by the alternator 6 _alt Lowering, the battery 8 contributes to the discharge phase.

This operation makes it possible to maintain the full performance level of the energy harvesting battery 10 by starting from an average state of charge of 90%, even if the on-board network battery 8 is used between two tasks of the vehicle.

In fact, in some phases (such as parking), the energy harvesting battery 10 is not available, because the capacity of this battery does not allow it to ensure the supply of power to all the electronic systems of the vehicle. This powering function risks dropping the state of charge of the on-board network battery 8 below 90%. If state of charge SOC ₈ Still satisfactory (in this case higher than 85%), the power supply system 2 will operate almost completely and the on-board network battery 8 will be charged during the harvesting phase and not prevent most of the discharging phase of the energy harvesting battery 10. On the other hand, if the state of charge SOC ₈ Falling too low, there will be a forced charge phase until the state of charge SOC ₈ The threshold value of 85% has been exceeded.

Setpoint voltages other than the above values are contemplated without departing from the scope of the present invention.

Preferably, the setpoint voltage TC ₁ Is calculated as a voltage V _batt10max Multiplied by a factor between 0.8 and 0.99. Similarly, the voltage TC ₂ Is calculated as a voltage V _batt8max Multiplied by a factor between 0.8 and 0.99. Voltage TC ₃ Is calculated as a voltage V _batt8max Multiplied by a factor between 1.01 and 1.1.

Such a range of values allows the state of charge of the battery 8 to converge towards a relatively high state of charge, while allowing the power supply system 2 to be easily forced into an energy recovery mode and a limited energy recovery mode. As a result, it is possible to optimally delay the recharging of the on-board network battery 8 and thus maximize vehicle consumption savings.

Claims

1. A system (2) for supplying electric energy to a motor vehicle, the system comprising: network (4), the networkHaving at least one current-consuming component (14, 16, 18); a first accumulator (8) connected to the network (4) and having a first maximum no-load voltage; a second accumulator (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 capable of delivering electrical energy; and an electronic management unit (12) capable of driving the voltage (T) delivered by the alternator (6) while the vehicle is running _alt ) Characterised in that, when the vehicle is not in the energy harvesting phase, the electronic management unit (12) is configured to successively apply to the alternator (6), while the vehicle is running, a first setpoint voltage (TC) strictly between the first and second maximum no-load voltages, according to the state of charge of the first accumulator (8) ₁ ) Strictly between the first maximum no-load voltage and the first set point voltage (TC) ₁ ) Second set point voltage (TC) in between ₃ ) And a third setpoint voltage (TC) strictly lower than the first maximum no-load voltage ₂ )。

2. The system (2) of claim 1, wherein the electronic management unit (12) comprises a mapping (20) according to the state of charge (SOC) of the first battery (8) ₈ ) Value of the delivery voltage (T) _alt ) The electronic management unit (12) being configured to apply the voltage value (T) delivered by the map (20) while the vehicle is running _alt )。

3. The system (2) of claim 2, wherein if the state of charge (SOC) of the first battery ₈ ) Is lower than or equal to a first threshold value (S) ₁ ) The map (20) delivers the first setpoint voltage (TC) ₁ ) And if the state of charge (SOC) of the first battery (8) ₈ ) Higher than or equal to a second threshold value (S) ₂ ) The map (20) delivers the third setpoint voltage (TC) ₂ ) The second threshold value (S) ₂ ) Strictly above the first threshold (S) ₁ )。

4. The system (2) of claim 3, wherein the first threshold (S) ₁ ) Between 83.5% and 84.5%, and/or the second threshold (S) ₂ ) Between 90% and 92%.

5. The system (2) according to claim 3 or 4, wherein if the state of charge (SOC) of the first battery (8) ₈ ) Between a third threshold value (S) ₃ ) And a fourth threshold value (S) ₄ ) In between, the map (20) delivers the second setpoint voltage (TC) ₃ ) The third threshold value (S) ₃ ) Is higher than or equal to the first threshold value (S) ₁ ) The fourth threshold value (S) ₄ ) Strictly above the third threshold (S) ₃ ) And is lower than or equal to the second threshold value (S) ₂ )。

6. The system (2) of claim 5, wherein the third threshold (S) ₃ ) Between 84.5% and 85.5% and/or the fourth threshold (S) ₄ ) Between 88% and 90%.

7. The system (2) as claimed in any one of claims 1 to 6, wherein the electronic management unit (12) is configured to apply a voltage strictly greater than the first setpoint voltage (TC) when the motor vehicle undergoes an energy harvesting phase ₁ ) Of the fourth set point voltage (TC) ₄ )。

8. The system (2) of any of claims 1 to 7, wherein the first setpoint voltage (TC) ₁ ) Is calculated as the product of the second maximum no-load voltage times a first coefficient, and/or the third set point voltage (TC) ₂ ) Is calculated as the product of the first maximum float voltage times a second factor, the first and second factors being between 0.8 and 0.99.

9. The system (2) of any of claims 1 to 8, wherein the second setpoint voltage (TC) ₃ ) Is calculated as the first maximum no-load voltage multiplied by a factor between 1.01 and 1.1And (4) accumulating.

10. A method for supplying motor vehicles with electric energy by means of a system (2) according to any one of claims 1 to 9, wherein the electronic management unit (12) successively applies the first setpoint voltage (TC) to the alternator (6) while the vehicle is running ₁ ) The second setpoint voltage (TC) ₂ ) And the third set point voltage (TC) ₃ )。