FR2928049A1 - Additional cell for power supply system of motor vehicle, has electric energy storage unit and voltage converter that are connected in parallel, where cell is connected in series with electric energy storage device - Google Patents

Abstract

The cell (18) has an electric energy storage unit i.e. ultra-capacitor (19), and a step-up/step-down type voltage converter i.e. direct current/direct current (DC/DC) converter (20), that are connected in parallel, where the cell is connected in series with an electric energy storage device e.g. battery (12) such as 12 volt battery. The cell is connected in series with elementary cells. An independent claim is also included for a power supply system supplying power to an electrical network.

Description

1

CELL FOR ELECTRIC ENERGY STORAGE DEVICE AND POWER SUPPLY SYSTEM OF THE VEHICLE EDGE NETWORK. The present invention relates to an additional cell intended to be connected in series with an electrical energy storage device, such as a battery. The invention also relates to an electrical power supply system of the on-board network of a vehicle.

[0002] Conventionally, the electrical consumer components of a motor vehicle are connected by an on-board electrical network to an electrical energy storage device, such as a battery, and to a power supply harness associated with protection elements (fuse and relay). An electric generator, such as an alternator, provides electrical power to the battery and to the electrical consumer devices via the on-board power supply harness.

[0003] Figure 1 illustrates the architecture generally used in motor vehicles. This architecture is composed of a device 2 for storing electrical energy, such as a battery, a starter 3 and an electric power generator 4, for example an alternator or an alternator-starter. These elements are connected by a power supply line 5, which is connected to functional organs 6 and 7 of the on-board network, for example headlights or windscreen wipers. Fuses 8 and relays 9 protect the functional organs 6 and 7 against overcurrent. [0004] The enrichment of the functionalities of the vehicles and the conversion to electricity of numerous mechanical members have revealed new functional organs of high electrical power. The alternator 4 regulates the on-board voltage network, but generally does not allow to respond to the new peak powers. The battery 2 allows the network 2

electrical power to stabilize without however avoiding disturbances and network voltage drops.

In addition, among the very high power functional organs, starters require more and more power on the engines of high-capacity vehicles, especially in a cold climate environment.

These adverse effects are more common on vehicles equipped with a system for stopping and automatic restart of the engine (type STOP AND START). To try to solve these strong calls current and power, and associated electrical disturbances, different solutions have already been proposed.

[0008] For example, it has been envisaged to integrate a second battery or an equivalent system of the capacitive type on the network, for example ultra-capacitors.

It has also been proposed, to facilitate startup and to stabilize the network, to increase the power of the batteries. It has also been proposed an architecture with two batteries, one of 12 volts and the other of 42 volts.

Finally, it has been proposed also a local filtering of each functional organ against these strong current calls, the filtering being performed by large buffer capacities.

However, all these solutions have a number of drawbacks in particular in terms of the electrical architecture of the network: 25 difficulties of implementation of this architecture in the engine compartment, 3

increased mass of batteries due to their higher capacity and increased cost.

The object of the invention is to solve these problems while maintaining full compatibility with existing electrical systems. More specifically, the invention relates to an additional cell for an electrical energy storage device, the cell comprising an electrical energy storage unit and a voltage converter; the electrical energy storage unit and the converter are connected in parallel and the additional cell is intended to be connected in series with the electrical energy storage device, the cell forming, as it were, an additional element to the storage device energy.

When the latter is composed of elementary cells connected in series, the additional cell is then intended to be connected in series with the elementary cells. According to one embodiment, the energy storage device is a battery.

The electrical energy storage unit may comprise one or more ultra-capacitors that can be connected in series and / or in parallel. Said converter may be a DC / DC converter.

The electrical energy storage unit and the converter may each comprise two connection poles, the additional cell then advantageously comprising means for connecting or disconnecting a pole of the storage unit with a pole of the converter. 4

The invention also relates to an electrical power system of the on-board network of a vehicle, the system comprising an electricity generator, an electrical energy storage device and at least one cell connected in series between said electrical energy storage device and said edge network, said cell and said energy storage device being defined as indicated above.

The generator may be an alternator or an alternator-starter.

The operating mode of the voltage converter is preferably controllable and it comprises means for controlling the operating mode of the voltage converter, these means controlling the operation of the voltage converter as a function of the vehicle life phase.

Preferably, said control means position the converter: - in voltage booster just before starting the engine of the vehicle;

- in step down when the vehicle is in standby; and

- So as to regulate the voltage of the storage unit and the storage device when the vehicle is in rolling phase.

Preferably, when the vehicle is in standby, one of the poles of the storage unit is disconnected from one of the poles of the converter, which makes it possible to regulate the supply voltage of the on-board network. .

The system may comprise an assembly of several additional cells connected in series with the electrical energy storage device. According to a particular embodiment, a starter is connected in parallel with the energy storage device.

Other advantages and features of the invention will become apparent from the following description of several embodiments of the invention, given by way of non-limiting examples, with reference to the accompanying drawings and in which:

FIG. 1 illustrates the conventional architecture of the electrical power supply system of the on-board network of a vehicle, a network connecting electrical consumers of the vehicle; FIG. 2 illustrates an embodiment of an electrical power supply system of the on-board network of a vehicle including an additional cell according to the invention;

FIG. 3 shows the diagram of an embodiment of an additional cell; FIG. 4 shows the diagram of another embodiment of an additional cell;

FIG. 5 shows the electrical diagram of one embodiment of the invention; and

FIG. 6 illustrates a particular embodiment of a vehicle network power supply system including an additional cell according to the invention and a starter connected in parallel with the battery.

In FIG. 2, the electrical power supply system of the onboard network of a motor vehicle comprises, in a conventional manner, an electric energy generator 10 (for example an alternator or an alternator-starter, 6

but any type of mechanical energy converter into electrical energy may be suitable), a starter 11, a device 12 for storing electrical energy such as a battery, electrical consumers 13 and 14 connected to the generator 10, to the starter 11 and to the battery 12, via fuses 15 or relay 16 and using a power supply line 17. According to the invention, the system comprises an additional cell 18 connected in series with the energy storage device 12. The cell 18 is composed of an electrical energy storage unit 19 connected in parallel with a voltage converter. 20 of step-down / step-up type. The latter can take various known forms, a particular embodiment being shown in FIG. 4. When the additional cell is associated with a battery of a motor vehicle, the converter is a DC / DC type converter. The cell 18 can be considered as additional: in fact, taking for example the energy storage device 12 in the form of a 12-volt battery, which is generally composed of six elements in series, the cell can be considered as a 7th active element, that is to say an element whose voltage can be controlled. The alternator 10 allows, during the rolling of the vehicle, the charge of the battery 12 and the energy storage unit 19 of the cell 18.

The energy storage unit 19 is advantageously of low impedance. It preferably consists of one or more ultra-capacitors connected together in series and / or in parallel depending on the electrical characteristics desired for the storage unit. The components of the ultra-capacitors commonly used in the automotive industry provide a voltage of 2.5 volts. By connecting several elements in series, the ultra-capacity will be able to provide more electrical power, while by connecting them in parallel the ultra-capacity will be 7

able to provide more electrical energy. The ultra-capacitance configuration is therefore adapted according to the needs of the system.

In Figure 2, the cell 18 is connected in series with the pole + of the battery 12 and the connection 21 of the converter 20 is connected to ground. It is however possible to connect the cell 18 in series with the pole of the battery, the connection 21 of the converter then being connected to the + pole of the battery.

In the following figures, elements identical or equivalent to the elements of FIG. 2 are generally indicated with the same reference numbers.

[0033] Figure 3 shows an embodiment of an additional cell 18 according to the present invention. It comprises the energy storage unit 19, such as an ultra-capacitor, and the voltage converter 20. Several cells can be connected in series with the battery 12. Thus, several cells 18 can be used and connected. parallel to each other if more pulsed power is required or in series if there is a need to provide a lot of power for a longer time.

[0034] FIG. 4 shows a particular embodiment of the cell 18 comprising the energy storage unit 19, the converter 20 and means, in the form of a switch 22, for connecting or disconnecting the one 23 two poles 23 and 24 of the converter 20 with one of the two poles 25 and 26 of the energy storage unit 19. When the cell of FIG. 4 is integrated in the power supply system of FIG. a motor vehicle, the switch 22 is kept in the open position when the vehicle 25 is in standby, that is to say when the vehicle is stopped, engine off. The switch 22 is closed in the other phases of life of the vehicle. 8

The system of Figure 2 also comprises a control circuit 27 connected to the circuit 28 for control and diagnosis of the vehicle. The control circuit 27 manages the operation of the converter 20 as a function of the life phase of the vehicle (standby, pre-start, start-up or rolling phase).

The converter 20 has the function of regulating the voltage across the ultra-capacitor 19. It is step-down or voltage booster depending on the life phase of the vehicle. Thus, when the vehicle is in standby, the converter is positioned in step down (with the switch 22 open) so as to draw less current on the battery 12. Before starting the thermal engine of the vehicle, the converter is positioned by the control circuit 27 in voltage booster to load the ultra-capacity (storage of electrical energy in the ultra-capacity) and thus be able to have more instantaneous power at the start of the engine of the vehicle. After starting the engine while driving, the converter operates as a voltage regulator across the ultra-capacitor and regulates the charge of the battery.

The charging voltage of the battery is usually regulated at the output of the alternator (regulation as a function of temperature) with the aid of a regulation module. However, with a power system according to the invention, the alternator may not include such a regulation module, and therefore be less expensive, since the regulation of the charge voltage of the battery can be made by the converter ( by regulating the electric current flowing in the branch of the cell 18 comprising the converter 20).

The availability of additional power provided by the ultra-capacity makes it possible to manage the charging and discharging phases of the alternator without affecting the voltage of the on-board electrical system. The regulation can be done around a single voltage (for example 16 V) chosen according to the best performance of the alternator. This results in a reduction of electrical losses and possibly a reduction in fuel consumption. 9

When the vehicle is in standby, the converter 20 may be considered as a closed switch to supply the organs 13 or 15 requiring a permanent power supply. Advantageously, the converter 20 monitors the value of the standby current to detect possible electrical malfunctions, thereby protecting against electrical short circuits.

Upon awakening of the vehicle (by unlocking the doors for example), the converter 20 pre-charge the energy storage unit 19. The voltage to the edge network can reach 24 volts, which is usually the limit maintenance of current vehicle electrical networks. This voltage threshold is adjustable (for example by the number of elements of 2.5 V placed in series, making up the ultra-capacitance 19) and results from a compromise between gain / cost / desired performance of the additional cell 18 and characteristics of the electrical / electronic architectures of the vehicles incorporating the invention.

In the rolling phase, the system stabilizes the onboard network. The cell 18 is an additional energy buffer which allows energy management strategies allowing a decrease in fuel consumption of the vehicle. The system also allows the battery 12 to be recharged according to an optimized control law.

FIG. 5 represents an embodiment of the cell 18 of FIG. 2, with the energy storage unit 14 taking the form of an ultra-capacitor 50 connected in parallel with the DC / DC converter 20 The operation of the latter is controlled by the control circuit 27 connected to the circuit 28 for checking and diagnosing the vehicle. The converter 20 is a switching converter of a conventional type. It comprises a pulse generator of variable width 51 comprising a comparator 52 and an input 53 to which is applied an adjustable reference signal according to the vehicle information coming from the controller 28 of the 10

vehicle. The converter also comprises two switches 54 and 55 connected to the pulse generator 51 and each consisting of a MOS type transistor, respectively 56 and 57, and a diode 58 and 59. The pulse generator 51 delivers a signal variable width control according to the voltage across the ultra-capacitance 50, to regulate this voltage.

The two terminals 60 and 61 of the storage unit 19 are respectively connected to the + pole of the battery 12 and the power supply line 17 of the vehicle edge network.

The charge of an inductor 62 can store energy 10 in the form of magnetic energy.

The two switches 54 and 55 operate in opposition: when one is open, the other is closed. For example, just before starting the heat engine, the ultra-capacity is charged, the MOS transistor 56 is in an on or off state while the MOS transistor 55 is in a closed state. The converter 20 then operates as a voltage booster, called boost mode. The voltage VDEM available for starting the engine of the vehicle is equal to the sum of the voltage VREG between the terminals 60 and 61 (voltage across the ultra-capacitor) and the voltage VBAT at the + terminal of the battery 12. If VBAT = 12V and VREG = 2.5V, the available VDEM voltage for starting is 14.5V.

At startup, the battery 12 and ultra-capacity 50 are discharged. The cell 18 is sized to provide all the necessary current before the discharge. Just before starting (pre-start phase) switch 54 is open and switch 55 modulates or cuts off the supply voltage. At startup, the control circuit 27 permanently blocks the switches 54 and 55 in the open position. 11

During the driving phase, the control circuit 27 generates a signal for regulating the voltage across the ultra-capacity for its progressive charging and charging the battery 12. The switch 55 is permanently open . The voltage of the onboard network is set by the voltage of the alternator. During this phase, the ultra-capacitor 50 allows the stabilization of the network (all the impulse current passes through the capacitance). In the event of a thermal engine shutdown, the converter can allow the storage of energy in the ultra-capacity to facilitate the restart of the engine, which is particularly interesting for vehicles equipped with a system of stop and restart automatic engine (Stop & Start).

FIG. 6 represents an example of application of the invention to the power supply system of the on-board network of a vehicle. We find the same elements as in the embodiment of Figure 2, namely the device 12 for storing electrical energy (a battery for example), the additional cell 18 connected to the power supply line 17 of the network , in series with the battery 12. The cell comprises the electrical energy storage unit 19 (for example an ultra-capacitor) and the voltage converter 20, the electrical consumer units 13 and 14 connected to the line 17 through fuses 15 or relays 16. According to this embodiment, a starter 65 is connected in parallel with the battery 12. One 66 of the two poles 66 and 67 of the starter is connected to the ground 68, while the other pole 67 is connected to the junction 69 between the battery 12 and the cell 18. This embodiment allows the stabilization of the onboard network and the maintenance of a minimum voltage in the starting phase of the engine, which allows to guarantee the t power supply of the on-board computers, without the reset (reset) with a small value for the storage capacity 19 of the cell 18. In the case of Figure 2 where the starter is placed after the cell 18, it is necessary that the value 12

of the capacity of the cell 18 is sufficiently large (of the order of 300 to 600 Farad) to ensure all the starting current, whereas with the assembly of Figure 6, a small value of the capacity 19 is sufficient, the order of 1 to 10 Farad (since this capacity is dimensioned only to avoid the reset of the computers of the vehicle). Advantageously, the converter 20 may also be smaller in size.

Other embodiments than those described and shown may be designed by those skilled in the art without departing from the scope of the present invention.

Claims (19)

An additional cell (18) for an electrical energy storage device (12), characterized in that it comprises an electrical energy storage unit (19) and a voltage converter (20), the electrical energy storage (19) and the converter (20) being connected in parallel and said additional cell (18) being intended to be connected in series with the device (12) for storing electrical energy. 2. Additional cell according to claim 1 characterized in that the electrical energy storage device (12) is composed of elementary cells connected in series, the additional cell (18) being intended to be connected in series with the elementary cells. 3. Additional cell according to one of the preceding claims characterized in that the energy storage device (12) is a battery. 4. Additional cell according to one of the preceding claims characterized in that the electrical energy storage unit (19) comprises at least one ultra-capacity. 5. Additional cell according to claim 4 characterized in that the electrical energy storage unit (19) comprises several ultra-capacitors connected in series and / or in parallel. 6. Additional cell according to one of the preceding claims characterized in that said converter (20) is a DC / DC converter 7. Additional cell according to one of the preceding claims characterized in that the electric energy storage unit (19) and the converter (20) each comprise two connection poles (25, 26, 23, 24), the additional cell being characterized in that it comprises means (22) for connecting or disconnecting a pole (25) of the storage unit with a pole (23) of the converter. 14 8. Additional cell according to claim 7 characterized in that said means (22) comprise a switch. 9. On-board electrical power system (17, 15, 16, 13, 14) of a vehicle, the system comprising an electricity generator (10), an electrical energy storage device (12) and at least one cell (18) connected in series between said electrical energy storage device (12) and said edge network, said cell (18) and said energy storage device (12) being defined at one of the preceding claims. 10. System according to claim 9 characterized in that the generator (10) is an alternator or an alternator-starter. 11. System according to one of claims 9 and 10 characterized in that the operation of the voltage converter (20) is controllable and that it comprises means (27) for controlling the operation of the voltage converter (20). said control means being connected to an on-board controller (28) of the vehicle. 12. System according to claim 11 characterized in that said control means (27) determines the operation of the voltage converter (20) according to the life phase of the vehicle. 13. System according to claim 12 characterized in that said control means (27) position the converter (20) as a voltage booster before starting the engine of the vehicle. 14. System according to claim 12 characterized in that said control means (27) position the converter (20) in step down when the vehicle is in standby. 15. System according to claim 12 characterized in that said control means (27) position the converter (20) so as to regulate the voltage of the storage unit (19) and the storage device (12) when the vehicle is in the driving phase. 15 16. System according to claims 7 and 14 characterized in that, when the vehicle is in standby, one (25) of the poles of the storage unit (19) is disconnected from one (23) of the poles of the converter (20), which regulates the supply voltage of the on-board network. 17. System according to one of claims 9 to 16 characterized in that it comprises an assembly of several additional cells (18) connected in series with the electrical energy storage device (1 2). 18. System according to one of claims 9 to 16 characterized in that it comprises a set of several additional cells (18) connected in parallel with the electrical energy storage device (12). 19. System according to one of claims 9 to 18 characterized in that it comprises a starter (65) connected in parallel with the energy storage device (12).