FR2933647A1 - Electrical energy storing system for supplying electrical motor of e.g. electric motor vehicle, has supercapacitor for recharging supplying device, where charge power load of supercapacitor is higher than charge power of supplying device - Google Patents

Abstract

The system (3) has a rechargeable supplying device i.e. motor supplying battery (31), for electrically supplying an electrical motor, and an energy recharging device i.e. supercapacitor (32), charged by an external power source (2) e.g. recharge station, and for recharging the rechargeable supplying device. The supercapacitor has charge power load higher than charge power of the rechargeable supplying device, and is connected to the electrical motor supplying battery by a direct current/direct current converter (33). Independent claims are also included for the following: (1) a battery supplying recharging system comprising an external electric supply source (2) a method for storing electrical energy to supply an electrical motor of a motor vehicle.

Description

BACKGROUND OF THE INVENTION The invention relates to a system for storing energy for a motor vehicle of the electric or hybrid type, allowing fast charging of the battery pack. The invention also relates to a method for storing electrical energy in such a storage system. It also relates to a charging system of a battery pack comprising such a storage system. The invention has applications in the field of the automobile and, in particular, in the field of electric power supply of electric vehicles or hybrid vehicles.

State of the art In the field of the automobile, conventional motor vehicles, or fuel vehicles, which only operate by means of a heat engine, have disadvantages relating, in particular, to their pollution both atmospheric and sound as well as 'at the cost of their fuel consumption. To solve these disadvantages, car manufacturers have manufactured electric vehicles. These electric vehicles include an electrically operated motor. These electric motor vehicles have the advantage of having a relatively quiet engine. They also have the advantage of not polluting the atmosphere and require, as energy, the electric current, substantially cheaper than the fuel. However, electric vehicles have the disadvantage of having a low mileage, compared to that of a fuel vehicle. Indeed, depending on the type of battery (lead-acid battery, nickel-cadmium battery, lithium-ion battery, ...), their autonomy varies between about 50 and 200 km, which is far from the 800 to 1000 km of autonomy of a fuel vehicle. The battery of an electric vehicle must therefore often be recharged.

The recharging of the battery packs of an electric vehicle is effected by means of a charger adapted to be connected, on the one hand, to the vehicle and, on the other hand, to the electrical network such as the 220-volt network. The charger can be connected to the 220 Volt network either at the vehicle owner's home or at charging stations installed in specialized car parks. However, a full charge of battery is relatively long. It is, for example, eight hours for a full recharge and two hours for a recharge to about 30%. During the charging time, the vehicle is immobilized, this immobilization can be embarrassing, or even disabling, for the driver of the vehicle. This problem of battery life is all the more troublesome as the distance to be traveled by the vehicle is large. For these reasons, the use of electric vehicles is currently mainly urban.

In order to overcome the drawbacks of vehicles with only electrical operation, car manufacturers have developed hybrid vehicles, that is to say vehicles comprising several different energy sources. Generally, a hybrid vehicle comprises a heat engine associated with an electric motor. The operating principle of such a hybrid vehicle is generally the following: - in stationary phases where the vehicle is stationary, the engine and the electric motor are both stopped; - At startup, the electric motor ensures the movement of the vehicle to low speeds, for example 25 to 30 km / h; - as soon as a higher speed is reached, the heat engine takes over. Indeed, it is known that a heat engine has poor performance at low power. Its fuel consumption at low speed, especially at idle, is important. Therefore, when the vehicle is idling or driving at low speed, the engine is stopped while the electric motor is running. The propulsion of the vehicle is then provided by the power supply system. As soon as the speed reaches a predetermined threshold, of the order of 30 km / h, it is the fuel supply system that propels the vehicle. Thus, in urban areas, the vehicle runs on electricity and, on the road, the vehicle runs on fuel, this combination making it possible to limit the fuel consumption of the vehicle while limiting the necessary autonomy in electrical energy. Such a vehicle is therefore able to perform longer journeys than an all-electric vehicle. However, with current hybrid vehicles, even if their need for electrical energy is reduced, it is still necessary to immobilize the vehicle to recharge the battery of the electric motor. Indeed, whatever the battery, and whatever its energy storage capacity, its recharge power is limited. In other words, if the current batteries are able to store a large amount of energy, they can be recharged relatively slowly because of their available power. The vehicle must be immobilized for a relatively long time, substantially identical to the downtime of an all-electric vehicle, to recharge the battery. EP-B1-1377477 discloses an energy storage system in which two batteries are associated to increase the available energy density for the motor. In this system, a battery pack and a battery pack are connected to a controller. The charging battery is selected to have a higher energy density than the battery pack to provide power to the battery pack. If such a system makes it possible to space the charging periods of the battery, it does not however allow to decrease the charging time and therefore the downtime of the vehicle. On the contrary, as there are two batteries to recharge, the recharge time is further increased compared to a single battery, which also increases the time of unavailability of the vehicle.

DISCLOSURE OF THE INVENTION The object of the invention is precisely to remedy the disadvantages of the techniques described above. To this end, the invention proposes an energy storage system, for an electric vehicle or a hybrid vehicle, in which a battery supplies energy to the electric motor of the vehicle, this battery being itself recharged by means of a battery. supercapacitor. This supercapacity, although having a limited storage energy, has the advantage of supporting very high charging powers. The invention thus proposes to quickly recharge a supercapacitance that can subsequently transfer its electrical energy to the vehicle, even while it is in operation. More specifically, the invention relates to an energy storage system for a motor vehicle comprising: - a rechargeable power supply device capable of electrically supplying at least one motor, - a device for charging energy suitable, on the one hand , to be charged by an external power source and, secondly, to recharge the power supply device, characterized in that the power supply device is a motor power supply battery and the charging device is a supercapacity, said supercapacity having a charging power greater than the charging power of the supply device. The energy storage system of the invention may comprise one or more of the following characteristics: the supercapacity is connected to the battery pack via a DC / DC converter. the supercapacity comprises a connection means able to be connected to an electric charger. - The connection means is adapted to receive an alternating magnetic field and to generate an electric current. The invention also relates to a charging system for a motor vehicle battery, characterized in that it comprises: an external power source, an external charger, and a storage system for a motor vehicle battery. energy as previously described. This charging system may include one or more of the following features: the external charger is adapted to receive an electric current from the external power source and to produce an alternating magnetic field. a plurality of external chargers is installed on the road network at mandatory vehicle stopping points. The invention also relates to a method for storing electrical energy intended to supply at least one motor vehicle engine, characterized in that it comprises the following operations: - recharging a supercapacity from an external source during stopping the vehicle, - recharging a battery pack, by transfer of electrical energy supercapacity to said battery, during a movement of the vehicle. This method may include the following feature: - the recharge of the supercapacitance is performed punctually at high power, the recharging of the battery pack being performed continuously, at limited power.

The invention further relates to a motor vehicle comprising a storage system as described above.

Brief description of the drawings Figure 1 shows schematically the charging system of a hybrid or electric vehicle battery according to the invention. FIG. 2 represents examples of recharge curves of a battery, in the case of a conventional power supply device and in the case of an energy storage system according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION The invention relates to an energy storage system and a charging system for a hybrid or electric vehicle, or for any other type of vehicle comprising at least one electric motor. In a motor vehicle with electric motor, said motor is powered by a rechargeable battery power supply. The battery pack is associated with means capable of recharging said battery from an external electrical source, such as the 220V electrical network. An example of a charging system according to the invention is shown in FIG. 1. This recharging system 1 comprises, on the one hand, an external source 2 associated with an external charger 4 and, on the other hand, a charging system. energy storage 3. The external source 2 may be a charging station located on the public domain, such as a charging station of a parking lot. It can also be an electrical outlet connected to the 220 Volts network, for example a plug in the home of the vehicle owner. The external charger 4 may be a conventional charger for electrically connecting the external source and the storage means 3 to electrically power said storage means. In one embodiment of the invention, which will be described in more detail later, the external charger 4 may be a non-contact induction charger. The energy storage system 3 of the invention comprises a power supply device able to power the motor electrically. This power device is a rechargeable battery pack 31, connected to the vehicle's electric motor. The storage system 3 also comprises a supercapacitance 32 connected, on the one hand, to the external charger 4 and, on the other hand, to the battery supply 31. It furthermore comprises a connection means 34, mounted between the charger external 4 and supercapacitance 32, and adapted to receive said external charger. In a variant of the invention, the connection means is integrated in the supercapacity. A supercapacity is an electric charge device which comprises an ionic solution (electrolyte) and an electronic conductor (electrode) at the interface of which a double electrochemical layer is created by the accumulation of electric charges. In a supercapacity, the interface between the charges plays the role of a dielectric. The electrode contains activated carbon with a very high specific surface area. The combination of a high conductive surface and a very low dielectric thickness makes it possible to achieve a much higher charging power than that of battery technologies. According to the invention, the energy storage system 3 comprises a supercapacitor 32 associated with a battery 31. The supercapacity has the intrinsic characteristic of supporting very high powers, so it can be charged very quickly. On the other hand, it has a relatively low storage capacity compared to a battery pack. Moreover, the battery power supply has an energy vocation, it has a limited charging power. The battery pack 31 is therefore reloaded relatively quickly compared to supercapacitance 32. However, it has a high storage capacity.

It is therefore understood that, in the invention, the supercapacity 32 recharges very quickly. It then transmits the energy it has stored in the battery pack 31. The battery pack can thus be recharged via supercapacity, even if the vehicle is no longer immobilized. In fact, the system of the invention makes it possible to limit the immobilization time of the vehicle by a quick recharge of the supercapacitance which, once recharged, can transfer the energy that it has stored to the battery pack. In the above description, the recharging device of the energy storage system is described as a single supercapacity. It is understood that the recharging device may comprise several supercapacitors, connected in parallel, or preferably in series because in parallel, the base cell fluctuating between 1 and 2.7V, there will then be a very low voltage. In a preferred embodiment of the invention, a DC / DC converter 33, called a DC / DC converter, is connected between the supercapacitance 32 and the battery 31. Its role is to ensure the dosing of the circulating power. between the supercapacity and the battery pack. This DC / DC converter 33 thus makes it possible to maintain the voltage at the terminals of the supply battery at a substantially constant value in order to recharge said battery within the limits of its charging power. The system of the invention thus makes it possible to recharge the supercapacity at high power, punctually and quickly, resulting in immobilization of the vehicle for a relatively short time compared to the downtime necessary for a conventional battery recharge. The battery pack is then, itself, recharged at limited power, drawing energy from the supercapacitor, while the vehicle is in operation. This system has the advantage of not polluting the availability of the vehicle.

In one embodiment of the invention, the external charger 4 is a non-contact induction charger. Such a charger operates on the principle of electromagnetic induction; the external charger 4 and the connection means 34 are provided with electromagnetic coils. The external charger 4, connected to the external source 2, receives electric current in its coil. This coil produces an alternating magnetic field. This field is received by the coil of the connection means 34 which generates an electric current supplying the supercapacity. Such an induction charger is therefore devoid of contact, which allows a supercapacity recharge in various locations. Charging points may, for example, be installed in places where vehicles must necessarily stop, such as near traffic lights. They can also be installed on parking spaces or any other temporary stopping place for vehicles.

In this way, the supercapacity can be recharged without requiring a particular immobilization of the vehicle: it recharges at locations where the vehicle is immobilized by the very fact of the signaling or the very fact of its course. The existence of recharging points in places where the vehicles are necessarily at a standstill, such as traffic lights, would allow a one-time recharging of the battery via supercapacity. In Figure 2, there is shown examples of recharge diagrams with a battery alone and with the storage system of the invention. In particular, on the channel A, there is shown, as a function of time, the recharging power of a single battery, for example in the case of a conventional vehicle. As seen on this channel A, the battery pack is charged to the maximum power P1 for a time interval t1. During this time t1, the vehicle is immobilized and therefore unavailable to its driver. During time t2, the charging of the battery being completed, the vehicle is available. It is therefore understandable that, in the case of a rechargeable battery only, periods of availability of the vehicle and periods of unavailability succeed one another more or less quickly depending on the use of the vehicle (urban routes, road, etc.). . There is no cumulation of a recharge period with a period of availability.

Even if the vehicle is not available for traction (since it is in the process of exchanging power with a fixed charging infrastructure) the battery is still available, even during recharging, to supply the network. for example.

On the track B of Figure 2, there is shown, as a function of time, the charging power of the battery, in the case of a vehicle equipped with the energy storage system of the invention. During time t3, the battery and the supercapacity are recharged. The supercapacity recharges at a power P3 much higher than the charging power P1, shown on channel A, of a single battery. The battery itself is recharged at a power P2, significantly lower than the recharge power P3 supercapacitance. During the time t4, the supercapacity stopped recharging. The charging power P4 of the supercapacitance, during the time t4, is then negative because this power P4 corresponds to the transfer of energy from the supercapacitance to the battery. In other words, the energy stored in the supercapacitor during the time t3 is transmitted to the battery during the time t4. The time t5 corresponds to a new recharge period of the supercapacity. It can be seen in this FIG. 2 that the power P2 of the battery of the storage system of the invention is less than the charging power P1 of a single battery. However, the battery recharge is continuous: the battery recharges at constant power P2, both during time t3 than time t4. During times t3 and t5, the vehicle is stopped. Supercapacity recharges during this stop. At time t4, the supercapacity being recharged, the vehicle is potentially rolling, that is to say it is available, while the battery continues to recharge at power P2. The system of the invention thus allows a continuous recharging, with constant continuous power, of the battery, with short-term immobilizations of the vehicle, compared to the fixed assets of channel A. In one example, a supercapacity of 1 MJ is used. rechargeable at a power of 60 kW with a recharge time of 17 seconds, this super capacity being discharged in traction at an average speed of 40 km / h is 2 kW electric in 8 minutes.

It is therefore clear that, in the system of the invention, one (or more) supercapacity is used to quickly store a large amount of energy, thanks to its ability to large powers. It is then possible to make transparent a recharge of the system, by performing the recharge of the supercapacity masked time during a normal stop of the vehicle on a road course and by continuously recharging the battery, when the vehicle is rolling . Such a system allows at least to maintain the battery charge in urban areas, facilitating the management of the battery for the driver. It also reduces the total charging time of the battery plug, with a fully immobilized vehicle.

Claims (1)

CLAIMS1 - Energy storage system for a motor vehicle comprising: - a rechargeable power supply device (31) capable of electrically supplying at least one motor, - an energy charging device (32) able, on the one hand, to to be charged by an external power source (2) and, on the other hand, to recharge the power supply device (31), characterized in that the power supply device is a motor supply battery (31) and the charging device is a supercapacity (32), said supercapacity having a charging power greater than the charging power of the power supply device. 2 û energy storage system according to claim 1, characterized in that the supercapacitance (32) is connected to the battery supply (31) via a DC / DC converter (33). 3 - energy storage system according to claim 1 or 2, characterized in that the supercapacitor comprises a connection means (34) adapted to receive an electric charger. 4 - energy storage system according to claim 3, characterized in that the connecting means is adapted to receive an alternating magnetic field and to generate an electric current. 5 - system for recharging a battery for a motor vehicle, characterized in that it comprises: an external power supply (2), an external charger (4), and a power supply system. Energy storage device (3) according to one of Claims 1 to 4. 6 - Power battery charging system according to Claim 5, characterized in that the external charger (4) is capable of receiving an electric current. from the external power source and produced an alternating magnetic field. 7 ù battery recharge system according to claim 6, characterized in that it comprises a plurality of external chargers (4) installed on the road network at mandatory stopping locations of vehicles. 8 - A method for storing electrical energy for supplying at least one motor vehicle engine, characterized in that it comprises the following operations: - recharging a supercapacity from an external source during a stop of the vehicle recharging a battery pack by transferring electric power from the supercapacitor to said battery during a movement of the vehicle. 9 - Process according to claim 8, characterized in that the recharging of the supercapacity is performed punctually at high power, the charging of the battery pack being performed continuously, at limited power. 10 ù Hybrid or electric vehicle, characterized in that it comprises an energy storage system according to any one of claims 1 to 4.