OA18523A

OA18523A - Reconfigurable capacitive energy storage device, power supply system and electric vehicle incorporating said device.

Info

Publication number: OA18523A
Application number: OA1201800023
Authority: OA
Inventors: Jean-Michel Depond
Original assignee: Blue Solutions
Priority date: 2015-07-23
Filing date: 2016-07-20
Publication date: 2018-12-04

Abstract

The invention is situated within the field of electrical energy storage by capacitive effect, in particular in order to supply autonomous electric or hybrid vehicles. It relates to a reconfigurable electrical energy storage device, i.e. one in which the internal connections between the different energy storage modules can be modified. The device (100) according to the invention comprises: M × N storage modules (111-122), where M and N are strictly positive natural numbers, each storage module being capable of storing electrical energy by capacitive effect between a negative terminal and a positive terminal; contactors (131-140) arranged in order to make it possible to connect by their terminals Mi × Ni storage modules, in different combinations, each combination denoted by an index i comprising Mi branches (151-153) connected in parallel, each branch comprising Ni storage modules connected in series, where Mi × Ni ≤ M × N; and positive (102) and negative (101) electrical connection terminals to which are capable of being connected, in each combination, the ends of the branches connected in parallel.

Description

RECONFIGURABLE CAPACITIVE ENERGY STORAGE DEVICE, POWER

SUPPLY SYSTEM AND ELECTRIC VEHICLE INCORPORATING SAID

DEVICE

Technical field

The invention Is situated within the field of electrical energy storage, ln particular energy storage in capacitive form. It applies In particular to the power supply for autonomous electric vehicles. More specifically, the Invention relates to an energy storage device by capacitive effect, a supply system Incorporatlng this device, and an electric or hybrid vehicle Incorporatlng this device or this power supply system.

State of the prior art

A machine or an Installation utillzlng electrical energy for Its operation must often adapt the nature of the energy supplled thereto. This Is the case In particular when the energy is supplled In mechanical form (for example by a flywheel), or In an electrical form but with voltage properties and signal form (for example variable or direct voltage) that are unsuitable. Within the field of the power supply for autonomous electric vehicles, energy storage Is typically carried out in the form of an electrochemical charge transfer device. This essentially Involves electric cells (or accumulators) and fuel cells. These electrochemical energy storage devices deliver a direct voltage, while very often the electrical machines In the vehicles require altematlng voltage. For this reason, it Is common to combine an energy conversion device with these electrochemical energy storage devices. The energy conversion device can also adapt the voltage range dellvered by the electrochemical energy storage device to the voltage or the voltage range of the power supply of the electrical machine ln question. In order to optlmize the use of the energy stored by the electrochemical energy storage device, the energy conversion device Is highly optimized with respect thereto. In particular, the Input voltage range of the energy conversion device Is adapted to the output voltage range of the storage device, with the alm of minlmizlng the losses by Joule effect and increasing the energy efficiency. This adaptation Involves in practice palring the energy conversion device with the energy storage device, without the possibility of replacing the storage device by another having different characteristics, unless to the détriment of the energy efficiency.

In recent years, energy storage devices in capacitive form hâve developed rapidly. In particular, from now on, supercapadtors will hâve a sufficient welght-to-capaclty ratio to make it possible to envisage their use as a main energy source for the propulsion of electric vehicles. However, simply replacing an electrochemlcal energy storage device with a supercapacitor or a plurality of supercapadtors would lead to severe détérioration In performance values. In fact, an electrochemlcal energy storage device works over a relatively narrow voltage range, while a supercapacitor works over a relatively wide voltage range. An electrochemlcal energy storage device typically opérâtes over a voltage range of U_ref ± 15%, where defînes the nominal voltage value. Practlcally 100% ofthe useful energy of an electrochemlcal energy storage device is available over a voltage range [2/3 U,^; U_œr]. In contrast, over an équivalent voltage range [2/3 U_n; Un], with U_n the nominal value of the voltage in the charged state, a supercapacitor only gives access to approxlmately 50% of Its useful energy. Thus, over one and the same voltage range and for the same energy initially stored, a supercapacitor delivers two times less energy than an electric battery or a fuel cell.

Coupling a supercapacitor with an energy conversion device does not allow the stored energy to be effldently recovered for voltage values below 2/3 U_n. In fact, over a voltage range [2/3 Um_ax; U_max], an energy conversion device generally has an efficiency ofthe order of 98%. But this efficiency can fall significantly below 90% for voltages of less than 2/3 U_max.

Moreover, energy conversion devices generally operate at constant power. In the case of an electrochemlcal energy storage device, the voltage at the terminais of the device does not vary significantly, and therefore the losses by Joule effect, associated with power requlrement, remain limited. In the case of a supercapacitor, the voltage varies significantly during operation, and when the voltage drops, the current must compensate for this drop, causlng an Increase ln the losses by Joule effect.

Dîsclosure of the invention

A purpose of the Invention is in particular to overcome ail or part ofthe aforementioned drawbacks. In particular, a purpose ofthe invention is to propose an electrical energy storage device by capacitive effect that makes it possible to optimize the use of the stored energy.

A further purpose of the Invention Is to propose an energy storage device by capacitive effect that makes it possible to replace an electrochemlcal energy storage device effectively.

The energy storage device by capacitive effect must make It possible ln particular, when It replaces an electrochemlcal energy storage device coupled with an energy converter, to use this energy converter within a conversion range having relatively high efficiency, typically greater than 95%.

The energy storage device by capacitive effect according to the Invention Is based on using several basic energy storage modules, and reconfîguring the connection between these modules so that the energy storage device has over time, at its terminais, a voltage comprised within a desired voltage range.

More specifically, the purpose of the Invention Is a reconfîgurable electrical energy storage device comprising:

M x N storage modules, where M and N are strictly positive naturel numbers, each storage module being capable of storing electrical energy by capacitive effect between a négative terminal and a positive terminal, contactera arranged in order to make It possible to connect by their terminais M_f x N_t storage modules, in different combinations, each combination denoted by an index i comprising M_f branches connected in parallel, each branch comprising N₍ storage modules connected In sériés, where M_f x Ni < M x N, and • positive (102) and négative (101) electrical connection terminais to which In each combination, the ends of the branches connected In parallel are capable of being connected.

The energy storage modules by capacitive effect are typically supercapacitors or combinations of supercapacitors.

The contactons can be of any type and any technology, provided that they are capable of establishing or Interruptlng an electrical contact between at least two electrical points. For example, these may be switches, In particular controllable, controllable Inverters, or controllable commutators. These contactons can be described as neconfigunatlon contactons, Inasmuch as they make It possible to switch oven fnom one combination of stonage modules to anothen combination.

Despite the gneaten amplitude of voltage variation at the terminais of an enengy storage module by capacitive effect with respect to an electrochemlcal energy storage device by charge transfer, the reconfigurable energy storage device according to the invention can replace such a device without modifying Its electrical environment, and In particular the energy converter. In particular, the reconfigurable device can be arranged in order to hâve, between the two connection terminais, a voltage capable of varylng between a minimum voltage U_mm and a maximum voltage Umax·

Moreover, the reconfigurable device according to the Invention has the advantage of optimlzlng the design of the internai connections of the energy storage device. In fact, energy converters generally work at high power. The lower the voltage at which the energy storage device works, the higher the amperage of the current passlng through It, and therefore passlng through the energy converter. When the energy storage device by capacitive effect cannot be reconfigured, Its internai connections must be dimensîoned in order to pass high currents fiowlng at low voltage. This présupposés the use of relatively high-power connecter engineering, with large cross-sections for the passage of current, which ultimately causes additional constraints in terms of weight, volume and cost. In the case of the reconfigurable device according to the invention, a maximum permlsslble current can be defined, involving changes in the configuration in order to avoid an Increase ln the current beyond this threshold. The energy converter also benefits from the current limitation, which makes it possible te use smaller cross-sections for the passage of current. Working at a lower current, the energy converters also generally hâve the advantage of presentlng Improved energy efficiency.

When the reconfigurable energy storage device according to the Invention is associated with an energy converter, the losses by Joule effect can also be reduced. In fact, as these losses are a function of the square of the total current, they are limited when making the energy converter work ln a hlgh-voltage range, and thus ln a relatively low current range.

The reconfigurable energy storage device according to the Invention can be arranged in order te be within a safety configuration, I.e. a configuration ln which the positive electrical connection terminal and the négative electrical connection terminal are not llnked together by a storage module. In other words, each branch of storage modules Is Isolated from at least one ofthe positive and négative connection terminais. No current can then flow from the négative electrical connection terminal to the positive electrical connection terminal. The safety configuration can be useful ln particular so as to allow an operator to carry out maintenance tasks by limiting the risk of electric shock.

The safety configuration can for example be obtained by providing the reconfigurable electrical energy storage device according te the Invention with a safety contacter arranged in order to be able to adopt an Isolation position, ln which, for at least one combination of the storage modules, each branch Is Isolated from the positive electrical connection terminal and/or from the négative electrical connection terminal. The safety contacter îs for example placed between the positive ends of the branches connected in parallel and the positive electrical connection terminal or between the négative ends of the branches connected în parallel and the négative electrical connection terminal. Of course, the reconfigurable electrical energy storage device according to the invention can comprise several safety contactons, each being capable of connecting or isolating the positive electrical connection terminal, or the négative electrical connection terminal, from the end of one or more branches.

The safety contacter can be a manual or controlled contacter. If necessary, It can be controlled by the same control unit as the one driving the contactons arranged In order to produce the different combinations of storage modules.

The safety configuration can also be obtained without Introducing any spécifie safety contacter. The reconfiguration contactons, arranged In order to make It possible to connect the storage modules In different combinations, can In fact be drlven in such a way as to Isolate each branch of the positive electrical connection terminal, and/or the négative electrical connection terminal.

According to a particular embodiment, the M x N storage modules hâve one and the same maximum voltage Umod-max at their terminais and one and the same capacitance. The reconfiguration of the storage modules according to different combinations is then facilltated. In particular, If ail the storage modules were identically charged In previous combinations, then In any new combination where each branch comprises an Identical number of storage modules, the branches hâve one and the same voltage at their terminais and can therefore be connected In parallel without Involvlng energy transfer between the storage modules.

With the aim of charging the different storage modules Identically, the contactons can be arranged so that, for each combination, the product M₍ x Ni of the number of branches times the number of storage modules ln each branch Is equal to the number M x N of storage modules ln the reconfïgurable electrlcal energy storage device.

To the extent that approximately 90% of the energy of a capacitive storage module can be restored over a voltage range corresponding to two-thirds of the maximum voltage U_mtxJ._max at the terminais of this storage module, the contactors can be arranged so that, among the different combinations, the maximum number N_max of storage modules ln each branch is less than or equal to three times the minimum number N_mi_n of storage modules ln each branch.

In order to manage the reconfiguration of a combination of storage modules to another combination, the reconfigurable device can also comprise:

• a measurement unit, arranged in order to measure a control voltage between the négative terminal of a first storage module among the M x N storage modules, and the positive terminal of a second storage module among the M x N storage modules, identical to or different from the first storage module, and a control unit, arranged ln order to drive the controlled contactors as a function of the control voltage.

According to a first embodiment variant, the control unit is arranged so that, when the control voltage becomes less than a minimum voltage U_mm, or greater than a maximum voltage U_max, the controlled contactors are drlven in order to connect the storage modules in a new combination, in which the control voltage Is comprised between the minimum voltage U_m)n, and the maximum voltage U_max.

According to a second variant embodiment, the control unit is arranged so that:

• when the control voltage becomes less than a minimum discharge voltage Udech» the controlled contactors are driven in order to connect the storage modules ln a new combination, In which the control voltage Is comprised between a minimum operating voltage U_mm, and a maximum operating voltage U_max, where U_dech < U_mm < U_max, and/or • when the control voltage becomes greater than a maximum load voltage Uch, the controlled contactons are driven in order to connect the storage modules ln a new combination, in which the control voltage is comprised between a minimum operating voltage u_mln, and a maximum operating voltage U_max, where U_min < Umax < U^.

The measurement unit is for example arranged ln order to measure the control voltage between the positive and négative electrical terminais ofthe configurable device, I.e. between the ends ofthe branches connected in parallel.

The control unit and the storage modules can be arranged such that the voltage différence AU_max between the maximum operating voltage U_maxand the minimum operating voltage U_min Is greater than or equal to the maximum voltage Umod-max at the terminais of a storage module. When ail the storage modules hâve one and the same maximum voltage Umod-max at 20 their terminais and one and the same capacitance, this condition makes It possible to ensure that the addition or the removal of a storage module in each branch brings the voltage observed between the ends of the branches between the minimum operating voltage U_min and the maximum operating voltage U_max.

The control unit and the storage modules can also be arranged so that the number of storage modules capable of being added or removed in each branch during swltch-over from one combination to a next combination is less than or equal to a maximum number n_max, determined 30 so as to satisfy the relationship:

Ilmax Umod-max £ ûU max (nmax + 1) Umod-max where AU_max Is the voltage différence between the maximum operating voltage (J_max and the minimum operating voltage U_min between the positive and négative terminais of the reconfigurable device.

A subject of the Invention is also a power supply system capable of supplying power for a load, such as a power train of an electric or hybrid vehicle, and being recharged by a recharging station. The system comprises;

• a reconfigurable electrical energy storage device such as previously described, a third electrical connection terminal and a fourth electrical connection terminal, capable of being connected to the load or to the recharging station, and an energy converter capable of connecting the fîrst and second electrical connection terminais to the third and the fourth electrical connection terminais, and arranged In order to adapt the form of the voltage between the fîrst and second electrical connection terminais to the form of the voltage between the third and the fourth electrical connection terminais.

Advantageously, the power supply system comprises a reconfigurable energy storage device in which the control unit is arranged so that, within the voltage range comprised between the minimum operating voltage U_mi_n and the maximum operating voltage U_max, the energy converter has an efficiency greater than or equal to 90% or 95%.

According to a first variant, the supply system also comprises:

an electrochemical energy storage device by charge transfer, capable of storing electrical energy between a fifth electrical connection terminal and a sixth electrical connection terminal, and a controlled switch arranged In order to connect the third and fourth electrical connection terminais to the first and second electrical connection terminais of the reconfigurable electrical energy storage device or to the fifth and sixth electrical connection terminais of the electrochemical energy storage device by charge transfer.

According to a second variant, the power supply system also comprises:

• a generator unit, capable of deliverlng electrical energy between a seventh electrical connection terminal and an eighth electrical connection terminal, and • a controlled switch arranged in order to connect the third and fourth electrical connection terminais to the first and second electrical connection terminais of the reconfigurable electrical energy storage device or to the seventh and eighth electrical connection terminais of the generator unit.

The first and second variants can be combined in order to hâve available two additional energy sources as well as the reconfigurable device. Thus, according to a third variant embodiment, the controlled switch Is arranged in order to connect the third and fourth electrical connection terminais to the first and second electricai connection terminais of the reconfigurable electrical ènergy storage device, to the fifth and slxth electrical connection terminais of the electrochemlca! energy storage device by charge transfer or to the seventh and eighth electrical connection terminais of the generator unit.

Finally, a subject of the invention Is a vehicle comprising an electrlc power train and either a reconfigurable energy storage device as previously described, or a power supply system as previously described, the device or the power supply system being arranged in order to supply the power train with electrical energy.

Description of the figures

Other advantages and features of the invention will become apparent on reading the detailed description of Implémentations and embodiments which are in no way limitative, and the attached drawings, in which:

- Figure IA shows diagrammatlcally a first example of a reconfigurable energy storage device according to the invention comprising twelve storage modules;

- Figure IB shows diagrammaticaily a variant of the first example of a reconfigurable energy storage device according to the Invention;

- Figure 2 shows diagrammaticaily a second example of a reconfigurable energy storage device according to the Invention, Incorporating a measurement unit and a control unit;

- Figures 3A to 3E show different possible combinations of the storage modules of the reconfigurable device in Figure IA;

- Figure 4 shows an example of a power supply system 10 comprising the reconfigurable device ln Figure 2, as well as an energy converter.

- Figures 5A and 5B show an example of sequencing of the swltch-over of controlled inverters of the reconfigurable device in Figure IA during a reconfiguration between two combinations;

- Figure 6 shows the typical relatlonshlp between the useful energy accessible during a discharge of a capacitive element as a function of the voltage at its terminais;

- Figures 7A to 7E show different possible combinations for a reconfigurable energy storage device comprising slxteen storage modules;

- Figure 8 shows a power supply system comprising a reconfigurable energy storage device according to the invention and an electric battery.

Description of embodiments

As the embodiments described hereinafter are in no way limitative, variants of the Invention can ln particular be envisaged that comprise only a sélection of the characteristics described below in isolation from the other characteristics described, (even If this sélection Is Isolated within a sentence comprising these other characteristics) if this sélection of characteristics Is sufficient to confer a technical advantage or to differentiate the Invention from the prior art. This sélection comprises at least one preferably functional characteristic without structural details, or with only a part of the structurai details if this part alone Is sufficient to confer a technical advantage or to dlfferentlate the invention with respect to the prior art.

In the présent invention, by energy storage module by capacitive effect, or more slmply storage module is meant any assembly of one or more electrical capacitors connected together in such a way as to hâve two connection terminais, one described as négative terminal and the other as positive terminal. A capacitor is defined as any electrical or electronic component having two conductive plates separated by a dielectric and capable of storing opposite electrical charges on its plates. The plates are capable of being connected to éléments of an electrical circuit via the two connection terminais. In a storage module, the capacitors can be connected together In any type of combination. Preferably, all the capacitors of a storage module are of the same type (for example electrolytic or with insulatlon). Advantageously, they hâve the same properties In terms of capacitance, maximum voltage and Internai résistance. The storage module is Intended to store a relatively large quantity of electrical energy. By way of Illustration, each storage module can store a quantity of electrical energy of the order of a kilowatt-hour, for example comprised between 0.1 kWh and 10 kWh. For an energy storage application, a capacitor 1s commonly called a supercapacitor. Most of the existlng supercapadtors are based on the technology called electrochemlcal double layer*. According to this technology, the supercapacitor comprises two porous électrodes containing for example activated carbon and soaked ln an ionic solution.

It Is noted that a capacitor fs characterized malnly by its capacitance C and the energy E stored by the capacitor Is defined by the relationshlp:

E = ±CU² where U ls the voltage at the terminais of the capacitor that Is considered Idéal, I.e. it has in particular no Internai résistance. A capacitor can function over a voltage range defined between zéro voltage (U = 0) and a maximum voltage l/_max. It can thus potentially store and deliver a quantity of energy equal to:

E s= -CU²L· — 2^^Uma^

According to the present description, a contacter is defined as any electrical device capable of adopting at least two positions, namely a first position, called contact position, in which it establishes an electrical contact between two points such as connection terminais, and a second position, called isolation position, ln which it electrically isolâtes these two points from one another. The contacter can adopt a greater number of positions. It can also manage the connection between three points, one of the points being able altematively to connect to one of the two other points. Generally this Is referred to as an Inverter. The contacter can be actuated manually or can be controlled. In the latter case, it Is described as a control contacter*. A control contacter can be produced according to different technologies. In particular, It can be produced in the form of a transistor, or an electrical circuit comprising at least one transistor.

Figure IA shows diagrammatically an example of a reconfigurable energy storage device according to the Invention. In this embodiment, the device 100 comprises a négative connection terminal 101, a positive connection terminal 102, tweive storage modules 111-122, and ten controlled inverters 131-140. In the Interests of slmpliclty, the storage modules are denoted Individually or collectively by the reference 110, and the controlled Inverters are denoted Indivldually or collectively by the reference 130.

The storage modules 110 ail hâve the same electrical properties, plus or minus a few percentage points due to design variance and ageing of the electrical components. In particular, the storage modules 110 hâve one and the same nominal voltage U_mod-_max, and one and the same capacitance C. Thus they are each capable of storing one and the same quantity of electrical energy. The storage modules 111, 112 and 113 are connected in sériés in order to form a first branch 151. The storage modules 114, 115 and 116 are connected In sériés in order to form a second branch 152. The storage modules 117, 118 and 119 are connected in sériés in order to form a third branch 153. The connection of the storage modules 111-119 is permanent within each branch 151-153. In other words, the device 100 does not hâve means making it possibie to connect the storage modules 111-119 other than by combinations of three In sériés. The three remainîng modules 120-122 are on the other hand not connected together permanentiy. It should be noted that the storage modules 110 are shown in Figure IA in an arrangement of 4 columns by 3 rows. The number of storage modules can thus be defined by the product 4x3 or, more generally, M x N, with M = 4 and N = 3. However, it is Important to emphasize that only the total number of storage modules Is important in the context of the Invention, their arrangement being unimportant, provided that the desired connections (whether permanent or not) between the storage modules are possibie.

The device 100 also comprises five internai connection points 161, 162, 163, 164, 165. These connection points are described as Internai Inasmuch as they are not Intended to be connected outside the reconfigurable energy storage device 100 with a view to delivering the energy stored in the storage modules 110, or receiving energy to be stored in these modules. Nevertheless, the connection points 161-165 can be made accessible from outside the device 100, for example so as to serve as measurement points In order to monitor a voltage. The connection points 161-165 hâve the function in particular of simplifying the production of the reconfigurable energy storage device 100 by forming points capable of being connected to several eiements (storage modules and controlled contactera) of the device 100. The connection points 161-163 also hâve the function of making certain connection terminais (of the device 100 and/or of the storage modules 110) physically doser together. Thus they take the form of electric cables, for example. In the case in question, the connection point 161 brlngs the négative terminal of the storage module 113 doser to the positive terminai of the storage module 114, and to the positive terminai of the storage module 122; the connection point 162 brings the négative terminal of the storage module 116 doser to the positive terminal of the storage module 117, and to the positive terminal of the storage module 121; and the connection point 163 brings the négative terminal of the storage module 119 doser to the positive terminal of the storage module 120. Bringing certain connection terminais doser together makes it possible to use controlled Inverters, Instead of simple controlled switches. The number of controlled contactera can thus be reduced, which facilitâtes the production of the reconfigurable electrical energy storage device and increases its rellabllity.

The controlled înverter 131 îs arranged In order to connect the positive terminal of the storage module 114 either to the connection point 161, or to the positive connection terminal 102 of the device 100. The controlled înverter 132 Is arranged in order to connect the positive terminal of the storage module 117 either to the connection point 162, or to the positive connection terminal 102 of the device 100. The controlled Inverter 133 is arranged In order to connect the positive terminal of the storage module 120 either to the connection point 163, or to the positive connection terminal 102 of the device 100. The controlled inverter 134 Is arranged In order to connect the négative terminal of the storage module 113 either to the connection point 161, or to the positive connection terminal 101 of the device 100. The controlled Inverter 135 is arranged in order to connect the négative terminal of the storage module 116 either to the connection point 162, or to the négative connection terminal 101 of the device 100. The controlled inverter 136 is arranged in order to connect the négative terminal of the storage module 119 either to the connection point 163, or to the négative connection terminal 101 of the device 100. The controlled Inverter 137 Is arranged in order to connect the négative terminal of the storage module 120 either to the connection point 164, or to the négative connection terminal 101 of the device 100. The controlled inverter 138 is arranged In order to connect the positive terminal of the storage module 121 either to the connection point 162, or to the connection point 164. The controlled inverter 139 Is arranged In order to connect the négative terminal of the storage module 121 either to the connection point 165, or to the négative connection terminal 101 of the device 100. The controlled inverter 140 is arranged In order to connect the positive terminal of the storage module 122 either to the connection point 161, or to the connection point 165.

On reading the following description relating to the connections effectively established within the device 100, a person skilied In the art will know that other configurations than the one described with reference to Figure IA are possible. In particular, the connection points 164 and 165 may be dlspensed with. The controlled inverter 137 would then be arranged in order to connect the négative terminal of the storage module 120 either to the positive terminal of the storage module 121, or to the négative connection terminal 101 ofthe device 100. The controlled Inverter 138 may be replaced by a controlled switch arranged In order to connect, or not, the positive terminal of the storage module 121 to the connection point 162. Similarly, the controlled inverter 139 would then be arranged In order to connect the négative terminal of the storage module 121 either to the positive terminal of the storage module 122, or to the négative connection terminal 101 of the device 100. The controlled Inverter 140 may be replaced by a controlled switch arranged In order to connect, or not, the positive terminal ofthe storage module 122 to the connection point 161.

Figure IB shows a variant of the example of a reconfigurable energy storage device described with reference to Figure IA. In this variant, the device 1000 differs from the device 100 only in that it also Includes a switch 1001, called safety switch, arranged In order to adopt either a contact position (closed position) or an isolation position (open position). In the contact position, the safety switch 1001 connects the négative electrical connection terminal 101 to the négative terminal of the storage modules 120, 121 and 122. In the isolation position, it Isolâtes the négative electrical connection terminal 101 from the négative terminal of the storage modules 120, 121 and 122. The safety switch 1001 can typically be a manual switch. Such a switch can thus be opened by an operator prior to a maintenance operation on the device 1000, and closed at the end of the maintenance task. The switch 1001 can also be a controlled switch. In this case, it can be driven by one and the same control unit as the storage modules 111-122, or by a separate control unit. The device 1000 can adopt a safety configuration by driving the controlled inverters 131-140 and by manoeuvrlng (manually or automatically) the safety switch 1001 so as to isolate each storage module 111-122 of the négative electrical connection terminal 101 and/or of the positive electrical connection terminal 102. According to a first solution, the controlled Inverters 131-140 are driven ln order to form a first branch formed from the storage modules 111, 112, 113 and 122, a second branch formed from the storage modules 114, 115, 116 and 121, and a third branch formed from the storage modules 117, 118, 119 and 120, according to the configuration described below with reference to Figure 3B. According to a second solution, the controlled Inverters 131-140 are driven in order to form a single branch comprising the assembly of storage modules 111-122 connected ln sériés, according to the configuration described below with reference to Figure 3D. In each solution, the safety switch 1001 Is manoeuvred into the isolation position, so as to break the electrical connection between the négative electrical connection terminal 101 and the positive electrical connection terminal 102.

The reconfigurabie energy storage device 100 or 1000 can typically be arranged in order to hâve at each moment, between its connection terminais 101 and 102, a voltage capable of varying between a minimum voltage U_m(n and a maximum voltage this functional range having an amplitude less than the amplitude of the voltage variation at the terminais of a single storage module 110 between Its fully discharged state (Umod - 0) and its fully charged state (Umod = Umod.max). The device 100 or 1000 can then also comprise means for controlling the controlled inverters so that the voltage between the connection terminais 101 and 102 remains within this functional range [U_max; U_m,n]·

Figure 2 shows an example reconfigurable energy storage device comprising such means. In particular, the device 200 comprises, in addition to the éléments of the device 100, a measurement unit 201 arranged in order to measure a control voltage between two terminais and a control unit 202, arranged in order to drive the controlled ïnverters 130. The measurement unit 201 measures for example the voltage between the connection terminais 101 and 102 of the device 100. However, the control voltage may be measured between other points of the device 200, ln particular between the terminais of one of the storage modules 110, Inasmuch as this voltage Is représentative ofthe voltage at the terminais of the device 200. Such Is the case ln particular when ail the storage modules are identical, charged and recharged Identically at each moment, and when the combination of the storage modules Is known. The control unit can hâve purely a hardware architecture, or a software architecture capable of executlng a software program. It may be for example a programmable logic controller, a fïeld-programmable gâte array (FPGA), a processor, a microprocessor or a mlcro-controller. The reconfigurable energy storage device 200 may of course contain a safety switch, manual or controlled, slmllariy to Figure IB.

It should be noted that any change of combination Involves adding or removing at least one storage module connected ln sériés in the different branches of the reconfigurable device. At each reconfiguration, the voltage at the terminais of the device is thus increased or reduced by at least one times the voltage présent at the terminais of one of the storage modules at the moment of the reconfiguration change. So as to ensure that the reconfigurable device has, both before and after reconfiguration, a voltage comprised within the desired functional range [U_maxî U_mmL arrangements must be made so that the amplitude AU_max of the voltage range [U_max; U_mi_n] is at least equal to the maximum voltage U_mod._max at the terminais of one and the same storage module. Similarly, there is a maximum number of storage modules that can be added or removed from a branch during a reconfiguration. This maximum number corresponds to the number of times that the maximum voltage Umod-nwr at the terminais of one and the same storage module can be contained within the amplitude AUmax of the desired functional range [U_max; U_m,_n]. Thus, for a given combination, the number n of storage modules capable of being added or removed must satisfy the following relatlonship:

ⁿ Umod-max S EU_max < (îl + 1) U_mod -max

Figures 3A to 3E show different possible combinations of the storage modules 110 ln the device 100. In Figure 3A, the controlled Inverters 130 are arranged in order to form four branches ln parallel (M = 4) of three storage modules 110 connected ln sériés (N = 3). The controlled Inverters 131, 132, 133 thus connect the positive terminal of the storage modules 114,117 and 120, respectively, to the positive connection terminal 102 of the device 100. The controlled Inverters 134, 135, 136 connect the négative terminal of the storage modules 113, 116 and 119, respectively, to the négative connection terminal 101 of the device 100. The controlled Inverters 137 and 138 respectively connect the négative terminal of the storage module 120 and the positive terminal ofthe storage module 121 to the connection point 164. The controlled Inverters 139 and 140 respectively connect the négative terminal of the storage module 121 and the positive terminal of the storage module 122 to the connection point 165. In Figure 3B, ail the controlled Inverters 130 hâve modified their connection with respect to Figure 3A, apart from the controlled Inverters 131 and 132. Consequently, the device 100 forms three branches ln parallel (M = 3) of four storage modules 110 ln sériés (N = 4). The first branch comprises the storage modules 111, 112, 113 and 122, the second branch comprises the storage modules 114, 115, 116 and 121, and the third branch comprises the storage modules 117, 118, 119 and 120. In Figure 3C, the controlled Inverters 131, 135, 137, 138, 139 and 140 hâve modified their connection with respect to Figure 3B. The device 100 forms two branches In parallel (M = 2) of six storage modules 110 ln sériés (N = 6). The first branch comprises the storage modules 111-116, and the second branch comprises the storage modules 117-122. In Figure 3D, only the controlled Inverters 132 and 135 hâve modified their connection with respect to the combination ln Figure 3C. The device 100 thus forms a single branch (Μ = 1) of twelve storage modules in sériés (N = 12). In each of the combinations in Figures 3A to 3D, ail the storage modules 110 are incorporated into one of the branches. They are thus ail charged or discharged simultaneously. To the extent that they are Incorporated into branches each comprising one and the same number of storage modules, the storage modules 110 are identically loaded at each moment. Figure 3E shows a combination in which not ail the storage modules are used, namely the storage modules 120-122. The device 100 forms a single branch (M = 1) of nlne storage modules (N = 9). In this combination, the controlled Inverters 131, 132, 133 connect the positive terminal of the storage modules 114, 117 and 120, respectively, to the connection points 161, 162 and 163, respectively. The controlled Inverters 134 and 135 connect the négative terminal of the storage modules 113 and 116, respectively, to the connection points 161 and 162, respectively. The controlled Inverter 136 connects the négative terminal of the storage module 119 to the négative connection point 101 of the device 100. The position of the controlled inverters 137, 138, 139 and 140 Is not Important, as the storage modules 120-122 are not connected to the rest of the device 100.

It should be noted that when one or more storage modules 110 are not used in a given combination, this or these storage modules can be used In a subséquent combination, subject to each branch of the combination comprising one and the same number of storage modules that are not used. More generally, when the device 100 comprises several branches in parallel ln a combination (M £ 2), it is Important that each branch has one and the same voltage at Its terminais. In practice, this Implies that each branch comprises an assembly of storage modules that collective!y are charged Identically.

Combination with ar)energy_converter

The reconfigurable energy storage device according to the invention can typically be incorporated Into a power supply system also comprising an energy converter. The energy converter can be a direct current converter. This can also be a power Inverter, when the reconfigurable energy storage device supplies electrlcal energy under a load, or a rectifier when the reconfigurable device receives electrlcal energy from an extemal source.

Figure 4 shows an example of a power supply system 400 comprising the reconfigurable energy storage device 200 ln Figure 2 (the measurement unit is not shown) and an energy converter 410. The energy converter 410 opérâtes altemately as power Inverter and as rectifier, according to whether the reconfîgurable device 200 is supplylng energy or receiving It, respectively. It Includes two connection terminais 411 and 412, on the altematlng current side, and two connection terminais 413 and 414 on the direct current side. The connection terminais 411 and 412 are Intended to be connected to a load that must be supplied by the reconfigurable device 200; and the connection terminais 413 and 414 are connected to the négative connection terminal 101 and to the positive connection terminal 102, respectively, ofthe device 200.

As the efïiciency of an energy converter dépends on the voltage It receives at the Input, on two of its terminais, and the voltage that it must dellver at the output, on its other two terminais, It Is préférable to make it operate over predetermined voltage ranges. In the présent description, it Is considered that the average voltage between the connection terminais 411 and 412 Is constant. Only the voltage between the connection terminais 413 and 414 Is considered. The voltage range over which the efficlency Is optimum varies between a minimum voltage Umm and a maximum voltage U_max, and Is called optimum operating range [U_max; Umm]· This range Is for example determined so that the energy converter has an efficlency η greater than 90%, or greater than 95%. Typically, an energy converter has an efficlency η greater than 95% over an operating range the lower boundary of which U_mm Is approximately equal to two-thirds of the maximum voltage Umax, I.e. an amplitude equal to one third of the maximum voltage U_max.

Switch-over of the controlled inverters or, more generally, of the controlled contactors, should preferentially be carried out under low current flow conditions so as to avoid détérioration of these controlled contactors. A switch-over of the controlled contactors is therefore advantageously carried out with a low current, or even none. As a resuit, during a relatively short period of time (of the order of a few tenths of a second), corresponding to the period necessary for changing the combination of the storage modules 110, only a limited quantity of energy, or no energy, can be transferred between the device 200 and the energy converter 410. The energy converter 410 Is thus advantageously informed of the change In the combination of the storage modules 110, so as to limit the energy conversion demand. This temporary limitation on the supply of electrical energy can Introduce a diffîculty In applications of the uninterruptible power supply type, which by définition need a constant energy supply. An uninterruptible power supply system Is used for example as a back-up power source, making It possible to ensure continuity of the energy supply service when the mains electriclty grid is down. A solution is to couple the reconfigurable energy storage device 200 with another electrical power source, such as a charge transfer electrochemical energy storage device. For other applications, temporary limitation of the electrical energy supply does not présent any difficulty. By way of example, the reconfigurable device 200 and the supply system 400 are particularly well adapted to applications of the electric or hybrid vehlcles* and network filtering types. The expression electric or hybrid vehicle dénotés the group of vehlcles Intended for transporting people and/or goods, and based on at least partial, and/or Intermittent use of an electric motor for moving the vehicle. The vehicle is for example an underground train, a tram, a bus, a boat, a car, a two-wheeler, a lorry, a travelling platform, a lift or a crâne. The electric or hybrid vehicle benefits from a mechanical Inertla that can overcome the energy supply limitation. The term network filtering dénotés the set of electrical devices making it possible to Improve the quality of the energy supplied by an electridty grid. Currently, some devices are based malnly on capadtors arranged In order to optimize the power factor (cos phi) of an altemating current electrical grid. Other devices comprise charge transfer electrochemical energy storage devices, making it possible to smooth an intermittent energy flow, for example produced by wind turbines or photovoltaic panels. Electrochemical energy storage devices accumulate energy during a sudden power Increase, as a resuit for example of a gust of wind or when the sun retums from behind a cloud, and release additional energy during sudden power decreases, for example as a resuit of the wind droppîng, or a cloud passing over the sun. The capacitors and the electrochemical energy storage devices of these devices can thus be replaced by the reconfigurable energy storage device according to the invention.

Other précautions must be taken during the swltch-over of the controlled contactons. In particular, ît Is préférable to avoîd momentarily piacing ln parallel, branches containing different numbers of storage modules ln sériés. Otherwise, some storage modules will discharge Into other storage modules, which will lead to Imbalance ln their state of charge. It Is thus préférable to manoeuvre the controlled contactons ln a certain order, or even to manoeuvre controlled contactons that a priori, in view of the initiai combination and the final combination, need not hâve been moved, in order to momentarily isoiate branches from one another.

A further précaution to be taken during swltch-over of the controlled contactons relates to the voltage présent at each moment at the terminais of the reconfigurabie energy storage device. This voltage must typically be comprised within a predetermined voltage range, for example the optimum operating range U_mi_n] of the energy converter. To this end, the control unit can be arranged so that, during any change of combination, any branch connected to the négative 101 and positive 102 connection terminais of the device 100 has the same number of storage modules ln sériés as either that of a branch of the combination before reconfiguration, or that of a branch of the combination after reconfiguration.

Figures 5A and 5B show an example of sequencing of the switchover of the controlled inverters 130 while swltch-over from the combination (Figure 5A) comprising four branches In parallel of three storage modules 110 connected In sériés (M x N = 4 x 3) to the combination (Figure 5B) comprising three branches in parallel of four storage modules 110 in sériés (M x N = 3 x 4). In a first step, marked Q, the controlled Inverters 133, 134 and 135 are activated, which has the effect of disconnecting the storage modules, respectively 120, 113 and 116, from the négative 101 and positive 102 connection terminais. In a second step, marked (2), the controlled inverters 137 and 139 are activated. In a third step, marked (3), the controlled Inverter 136 Is activated. In a fourth step, marked φ, the controlled inverters 138 and 140 are activated. In each step, the controlled Inverters can be activated successively or simultaneously.

With the alm of ensuring that the swltch-over of the controlled contactors Is carried out In the desired order, provision may be made for a mechanism for verifying the position of the different controlled contactors. This vérification mechanism for example sends data feedback to the control unit, allowing It to actlvate the successive swltch-overs of the controlled contactors.

Generallzatlon

It is noted that the reconfigurable energy storage device according to the Invention can include any number M x N of storage modules, with M and N two natural numbers greater than or equal to one. Different optimlzatlons of the combinations are possible, in particular ln terms of available energy, efficiency of the energy converter and/or number of configurations.

Optlmlzatlon In terms of available energy

The optlmlzatlon In terms of available energy assumes that at any time, the assembly M x N of storage modules Is used. In other words, regardless ofthe combination i, the following relatfonship is complied with: M| x N_t = M x N

The following combinations, defined by a pair M₍ x N₍, are possible ln particular:

Initial M	Mi x Ni	M₂ x N₂	M₃ x n₃	M₄ x N₄	M_s x N₅	M₆ x Ne
3	3 x 2k	2 x 3k	1 x 6k
4	4 x 3k	3 x 4k	2 x 6k	1 x 12k
5	5 x 4k	4 X 5k	2 x 10k	1 x 20k
5	5 x 12k	4 x 15k	3 x 20k	2 x 30k	1 x 60k
6	6 x 2k	4 x 3k	3 x 4k	2 x 6k	1 x 12k
6	6 x 10k	5 x 12k	4 x 15k	3 x 20k	2 x 30k	1 x 60k
7	7 x 6k	6 x 7k	3 x 14k	2 x 21k	1 x 42k
8	8 x 3k	6 x 4k	4 x 6k	3 x 8k	2 x 12k	1 x 24k
9	9 x 4k	6 x 6k	4 x 9k	3 x 12k	2 x 18k	1 x 36k

In these combinations, k is a strictiy positive naturai integer and makes It possible to indicate that the Integer Nj is a multiple of the specified integer. Furthermore, M can be a multiple of the integer In question, providing that it is not desired to use the combinations In their entirety. For example, the sériés of combinations starting with 6 x 2k is merely a continuation of the first terms of the sériés starting with 3 x 2k, grouping the branches two by two. The same goes for the sériés starting with 8 x 3k and 4 x 3k.

Optimization ln terms of efficiency ofthe energy converter

When the reconfigurable device according to the invention is combined with an energy converter, it is bénéficiai to use combinations such that the voltage at the connection terminais of the device can be situated at each moment within the optimum operating range [Uma_X; U_mi_n] of this energy converter. This condition is expressed by the following relationship:

w_J+1 ^> where Is defined by:

The sériés of combinations starting with 9 x 4k for example offers good optimization Inasmuch as between each consecutive combination, the ratio of N_t to Ni+i is always greater than two-thirds.

The following table présents different possible combinations making It possible to optimlze the efficiency of the energy converter in the case where k_n = 2/3. U_devlce._max and Udence-min respectively dénoté the maximum and minimum voltages at the terminais of the reconfigurable device.

	Combinations	M	N	tldevtce-mix		Udfvtce-mln	Umod-mln	Usabie energy
A	1	4	3k	3k U_n	u_n		l·-	55%
2	3	4k	6 g3kl/„	²3^u*			75%
3	2	6k	3k U„		5 ^υ-		89%
B	1	6	2k	2k IA.	Un	fa».	l·-	55%
2	4	3k	2k U_n	2 ï^Un	I·	4 g IA,	80%
3	3	4k	8 ç2kl/_n	4 g Un	J²*	3 ^Un	89%
	1	9	4k	4k U_n	Un		l··	55%
C	2	6	6k	4k U_n	2 3	\|«K.		80%
3	4	9k	4kl/_n	5” j			91%

The following table présents different possible combinations making it possible to optimize the efficiency of the energy converter in the case where Jt, = 3/4.

Combinations	M	N	l^devlte-mix	Umod-mj»	Udevlce-mln	t^mod-mln	Usabie energy
1	6	10k	10k U„	Un	\|10kt/_B	\|ia,	44%
2	5	12k	^10*1/.		j 10k U„	8 ^Un	61%
3	4	15k	15 , Ï6^10fey	8 ^U”	~10kU„	2 Un	75%
4	3	20k	10k U_n	1 2^Ü	110k u_n		86%

It should be noted that this sériés of combinations Is the only one to respect the condition:

Nt ^3 n_M 4

Any other Initiai combination requires leaving unused storage modules in 10 one of the following combinations, unless the Integer k makes It possible to pass through an Intermediate combination respectlng the above condition. For example, in the case of a reconfigurabie device with the Initiai combination M x N = 8 x 15, the following sériés of combinations Is possible.

Combinations	M	N	Udevfce-max	Umod-max	Udevtce-mln	Umod-mln	Usable energy
1	8	15	151/.	U_n	\|15t/_n	h-	44%
2	6	20	15t/„			H·	68%
3	5	24	il·⁵·		;1SU.	M.	78%
4	4	30		15 32 ^Un	\|15t/_B		86%
5	3	40	ist/i,		U_n	è·	92%

The following example, still In the case where Ιι_η = 3/4, shows how it is possible to manage a sériés of reconfigurations while leaving out storage modules In certain combinations, In order to relncorporate them In 5 a following combination.

Combinations	M	N	Udevice-max	Umod-max	UdevWe-min	Umod-nMri	Usable energy
1	4	8	8 Un	l'a			44%
2	3	10	—8U_B 16	h-	\|βσ,,		60%
-	2	Isolated moc	ules. Voltage stabilized at jl/_B
3	2	12 + 1	160	l·· h-		à·	64%
-	6	Isolated moc	ules. Voltage stabilized at \|u_B
4	2	12 + 4	39 ïô^8t/	I».		27 80^ 80	86%

In this iatter example, combination 2 leaves out two storage modules. As no current passes through these modules, they remain in the same state of charge throughout the period of the combination. 10 Combination 3 relntroduces the two modules isolated in combination 2, at the rate of one per branch, and Isolâtes six others therefrom. Combination 4 reintroduces the six isolated modules, at the rate of three storage modules per branch, .

Qptlmlzation in terms of number of reconfigurations

Figure 6 shows a characteristic of a energy storage module by capacitive effect. It represents the useful energy accessible during a discharge of the storage module as a function of the voltage at its terminais at the end of discharge. The x-axis corresponds to the voltage at the end of discharge, as a percentage with respect to the maximum voltage U_mod._max, and the y-axis corresponds to the accessible useful energy, as a percentage with respect to the total energy available In the storage module. This figure shows that 90% of the nominal energy of the storage module Is accessible over a voltage range [U_mOd._mex; U_mod-_minL where Is approximately equal to one third of Umod-max. Thus, the use of 90% of the energy of the reconfigurable energy storage device according to the invention requires a maximum number of storage modules per branch strlctly less than three times the minimum number of storage modules per branch. The strict Inferlorlty relationship Is due to the voltage variation at the terminais of the storage modules. The combinations can thus be the following:

Initial M	Mi x Ni	M₂ x N₂	M₃ x N₃	M₄ x N₄
3	3 x 2k	2 x 3k
4	4 x 3k	3 x 4k	2 x 6k
5	5 x 4k	4 X 5k	2 x 10k
5	5 x 12k	4 x 15k	3 x 20k	2 x 30k
6	6 x 2k	4 x 3k	3 x 4k
6	6 x 10k	5 x 12k	4 x 15k	3 x 20k
7	7 x 6k	6 x 7k	3 x 14k
8	8 x 3k	6 x 4k	4 x 6k	3 x 8k
9	9 x 4k	6 x 6k	4 x 9k

As previously indicated, the control unit can drive the controlled contactons so that the voltage U_device at the terminais of the reconfigurable device according to the invention Is situated within the voltage range [U_max; UminL corresponding for example to the optimum operating range of the energy converter. The control unit can thus be arranged so that, when the voltage U_device becomes less than the minimum voltage U_min, or greater than the voltage U_max, the controlled contactera are driven in order to connect the storage modules in a new combination, in which the voltage Udevice retums within the voltage range [U_max; U_mm].

As the energy converter can Introduce voltage oscillations, of the order of a few volts, a phenomenon of erratlc oscillation between two combinations can be noted If the change of combination Is carried out at one and the same voltage, both on charging and on dîscharging of the reconfigurable device. In order to avoid such a phenomenon, It Is possible to Introduce hystérésis of several volts (for example 1 to 5 volts) a round each voltage of the change In combination. By way of Illustration, a first combination of Mi branches in parallel is consldered, each having Ni storage modules, and a second combination of M₂ branches In parallel each having N₂ storage modules, with N₂ > Ni and Mi x Ni = M₂ x N₂. Under discharge, the switch-over from the first combination te the second can be carried out when the voltage Udevice reaches a voltage Ud«h that Is a few volts less than the voltage U_mi_n. On the other hand, under charge, the switch-over from the second combination te the first can be carried out when the voltage U_devlce reaches the voltage U_mi_n.

Another solution for Introducing a hystérésis is to work with a ratio NJN₂ that Is slightly above the quotient of the minimum voltage U_min over the maximum voltage U_max, while retalning the reconfiguration thresholds at the terminais of the optimum operating range [U_max·, U_mi_n]. Under discharge, the voltage U_devke changes from ü_min = k_n U_max to N_t/N₂ .Uminr which is very slightly less than U_max. Under charge, the voltage Udevice changes from the voltage U_max te Ni/N₂.U_maxt which is very slightly less than k_n U_max. With respect to the previous one, this second solution has the advantage of retalning a voltage Udevice In the optimum operating range of the energy converter.

The reconfigurable energy storage device according to the Invention Is particularly suitable for supplying electric public transport vehldes, ln particular when they carry out journeys Including predetermined halts at bus stops. Such Is the case ln particular for buses and trams. The reconfigurable energy storage device of the vehicle can In fact be recharged regularly during the halts at stops, making It possible for It to accumulate sufficient energy In order to travel autonomously between the stops. The stops are then described as charging stations*. The technology of energy storage by capacitive effect, covering in particular supercapacltors, aiiows relatively short durations for recharglng, compatible with the period that the vehicle is halted at a stop, typically of the order of around ten seconds, or even a maximum of around thirty seconds.

According to a first example of use of the reconfigurable energy storage device according to the invention, this device supplies a vehicle including a drive train (Infinltely variable speed transmission + motor) operating over an Input voltage range comprised between 300 V and 450 V, with an optimum energy efficiency comprised between 330 V and 430 V. In order to better understand the advantages of the use of a reconfigurable device according to the Invention, flrstly, by way of comparison, a nonreconflgurable energy storage device by capacitive effect Is considered, I.e. one in which the combination of storage modules Is fixed. This nonreconflgurable device comprises for example four branches in parallel of eight storage modules connected ln sériés, each storage module having a maximum voltage between its terminais Umod-max of 50 V. Thus, the maximum voltage at the terminais of the device Is 400 V, which is dose to the upper boundary of the optimum operating range of the drive train (430 V). On the other hand, discharglng the non-reconfigurable device until Its voltage reaches the lower boundary of the optimum operating range (330 V) only aiiows a small part of the energy stored in the device to be used, i.e. approximately 33%. This part can reach approximately 50% If discharge Is allowed to a voltage of 300 V, but remalns relatively small. For a given autonomy of the electric vehicle, this rate of use of the stored energy requlres over-dimenslonlng of the non-reconfigurable storage device.

The reconfigurable energy storage device according to the Invention makes It possible to Increase the autonomy available based on one and the same number of storage modules, to optimize the number of branches ln parallel, or to reach a compromise between these two options.

In the case of an Increase in autonomy, it can be observed that, according to the table presented below with one Initial combination of four branches In parallel, each having elght storage modules, up to 86% of the stored energy can be used. In the case where optimization of the number of branches is sought, it Is noted that the reconfigurable device can comprise 10 only two branches ln parallel, each having eight storage modules (M x N = x 8). The following combinations can be used.

Combinations	M	N	Udevice-nwt	Llmod-mix	Udev<ce-<nln	Urnod-mln	Usable energy
1	2	8	400	50	330	41.25	32%
2	1	10	412,5	41.25	330	33	35%
-	6	Isolated modules. Voltage stabilized at 41.25 V
3	1	6 + 5	412.5	41.25 33	330	33.75 25.5	44%
-	5	Isolated modules. Voltage stabilized at 33 V
4	1	6 +5 +2	418.5	33.75 33 25.5	330	27 26.2 18.5	60%
-	3	Isolated modules. Voltage stabilized at 25.5 V
5	1	6 +5 +2 +3	406.5	27 26.2 18.5 25.5	330	22.2 21.4 13.7 20.8	83%

Figures 7A-7E diagrammatically show the different corresponding combinations. In Figure 7A, showing the first combination, the device 700 IS comprises two branches ln parallel, each of elght storage modules ln sériés.

The first branch 710 comprises storage modules numbered consecutively from 1 to 8 and the second branch 720 comprises storage modules numbered consecutively from 9 to 16. In Figure 7B, showlng the second combination, the device 700 comprises a single branch formed from the 20 storage modules 1 to 10, the storage modules 11 to 16 being isolated. In

Figure 7C, showlng the third combination, the device 700 still comprises a single branch, but this time formed from the storage modules 1 to 3 and 9 to 16, the storage modules 4 to 8 being isolated. In Figure 7D, showing the fourth combination, the device 700 comprises a single branch formed from the storage modules 4 to 16, the storage modules 1 to 3 being isolated. In the last combination, shown in Figure 7E, the device comprises a single branch formed from the assembly of sixteen storage modules connected ln sériés. In order to allow these different combinations, the device 700 comprises a controlled contacter between the storage modules 3 and 4, between the storage modules 10 and 11, between the storage module 8 and the négative connection terminal of the device 700 and between the storage module 9 and the positive connection terminal ofthe device 700.

According te a second example of use of the reconfigurable device according to the Invention, this device supplies an electric vehicle the drive train of which opérâtes over an input voltage range comprised between 300 V and 750 V, with an optimum energy efficiency comprised between 350 V and 730 V. As the operating range is relatively broad (with U_ma>t > 2 Umin), it may be envisaged to use a non-reconftgurable energy storage device by capacitive effect. However, the reconfigurable device according to the invention is particularly bénéficiai for recharging the electric vehicle at a stop. In fact, on arrivai at a stop, the reconfigurable device can hâve a voltage at its terminais of 350 V and require recharging via an energy converter delivering a voltage of 700 V at its terminais. The energy converters are malnly of two types, namely step-up and step-down. With a step-up converter, the Input voltage range is less than the output voltage range. Now, as the recharging period needs to be short, high currents must pass between the station and the electric vehicle, which requires spécifie connectera and involves signîficant design and maintenance costs. Moreover, losses through Joule effect are signîficant. With a step-down converter, the input voltage range is greater than the output voltage range. A drawback of this energy converter is the safety risk. The recharging station Is typically situated in an urban environment, with a risk of electrical contact with passengera or passera-by. The presence of this high voltage and the signîficant power transferred thus requires very strict safety measures ln terms of mechanlcal intégration, materials and thus costs.

The reconfigurable energy storage device according to the Invention llmits these drawbacks by aiiowing recharglng in two stages. The reconfigurable device includes for example two branches (or a multiple of two branches) of fourteen modules in sériés, each storage module having a maximum voltage at Its terminais of 50 V. In the case of a step-up energy conversion device, operating for example over a voltage range comprised between 225 V and 450 V and an output voltage range comprised between 500 V et 1000 V, in a first stage, the two branches are placed ln sériés (or the branches are placed in sériés two by two) in order to form a branch of 28 modules. The voltage at the terminais of this branch will change from 700 V to 1000 V. In a second stage, the reconfigurable device retums to Its Initial configuration (Μ x N = 2k x 14) ln order to complété the recharglng of the storage modules, the voltage at their terminal changing from 500 V à 700 V. In the case of a step-down energy conversion device, operating over an Input voltage range comprised between 500 V à 1000 V and an output voltage range comprised between 225 V et 450 V, in a first stage, the reconfigurable device Is left ln its initial configuration (M x N = 2k x 14), the voltage at the terminais of each branch changing from 350 V to 450 V. In a second stage, each branch of fourteen storage modules Is divided Into two parallel branches of seven storage modules each. On recharglng, the voltage at the terminais of the branches changes from 225 V to 350 V. The device Is then reconfigured Into its initial configuration, each branch having a voltage at Its terminais of 700 V. In terms of Personal safety, the use of a step-down energy converter is préférable to the use of a step-up converter, inasmuch as the highest voltages are located upstream of the energy converter, a priori installed within the recharglng station and thus less accessible to people. The use of a step-up converter, on the other hand, places the highest voltages downstream of the energy converter, and in particular on the power connection device between the recharglng station and the vehicle, generally more accessible to people.

The reconfigurable device according to the invention has advantages as a power supply source of an electric vehicle. It can also be useful in a recharging station, in order to facilitate the transfer of energy during recharging of the reconfigura b le device on board the vehicle at a stop. The reconfigurable device arranged in the recharging station, called ground reconfigurable device*, has a relatively long time for recharging, of the order of several minutes, corresponding to the time interval between two halts of vehicles in the recharging station. The power transfer values are therefore markedly lower, which allows recharging directly from the electrlcity grid. A power supply system for an electric or hybrid vehicle can thus Include a first reconfigurable energy storage device according to the Invention, on board the vehicle, In order to supply It autonomously between two stops, a second reconfigurable device according to the Invention, placed in each recharging station, and an energy converter arranged In order to connect the two reconfigurable devices. The electrical properties of the drive train of the vehicle impose the voltage range of the on-board reconfigurable device and, consequently, the number of storage modules In sériés in each branch. The autonomy required between two recharging stations for its part sets the number of branches In parallel in the on-board reconfigurable device.

By way of example, an on-board reconfigurable device Is considered comprising, in an initial combination, four branches in parallel, each of elght storage modules in sériés, i.e. a total of thlrty-two storage modules. The energy to be transferred from the reconfigurable device on the ground to the on-board reconfigurable device corresponds to the useful energy for the vehicle to move between two recharging stations, disregarding the losses due to the energy transfer, in particular In the energy converter. The reconfigurable device on the ground thus comprises one and the same number of storage modules. The voltage range within which the reconfigurable device on the ground must operate Is imposed by the conversion ratio of the energy converter. In the case of a step-down energy converter with a ratio of 1/2, the reconfigurable device on the ground works at a voltage that is double that of the on-board reconfigurable device. Its thirty-two storage modules are thus connected In a combination of two branches In parallel of sixteen storage modules (M x N » 2 x 16). The on-board reconfigurable device and the reconfigurable device on the ground can be produced from one and the same basic reconfigurable device, comprising four branches of eight storage modules In sériés, and a connection system making It possible to choose either a parallel combination of the four branches, or a combination of two branches In parallel of sixteen storage modules. In the case of a step-up energy converter with a ratio of 2, the reconfigurable device on the ground Works at a voltage that Is half that of the on-board reconfigurable device. The thirty-two storage modules of this reconfigurable device are thus connected In a combination of eight branches In parallel of four storage modules In sériés. The on-board reconfigurable devîce and the reconfigurable device on the ground can also be produced from one and the same basic reconfigurable device, comprising eight branches of four storage modules In sériés, and a connection system making It possible to choose either a parallel combination of the eight branches, or a combination of four branches In parallel of eight storage modules. The connection system can include bus-bars, bolted at the end of production Into the required position according to the destination of the reconfigurable device, namely the vehicle or the recharglng station. The connection system can also Include manually-controlled switches, such as manual power breakers, the position of which Is determined as a function of the destination of the reconfigurable device. It must be noted that the destination of the reconfigurable device Is a priori definitive. It Is therefore not necessary for the connection system used to be capable of being controlled. However, controlled contactors such as those used during charglng or dlscharglng of the reconfigurable devices can be used.

The reconfigurable energy storage device according to the invention can be combined with other electrical power supply sources, In particular with a charge transfer electrochemlcal energy storage device (electric battery or fuel cell), or a generator unit. These additional power supply sources can back up the reconfigurable device In the case of short power cuts, for example during the changes of combination, as well as in the case of sudden power demand, or when the reconfigurable device is discharged.

Figure 8 shows an example of a power supply system comprising an electrical power supply source in addition to the reconfigurable device according to the Invention. The electrical power supply system 800 comprises a reconfigurable device 810, an energy converter 820, an electric battery 830 and a controlled switch 840. The reconfigurable device 810 comprises a négative connection terminal 811, a positive connection terminal 812, an assembly of storage modules 813, and an assembly of controlled Inverters 814. The electric battery 830 comprises a négative connection terminai 831 and a positive connection terminai 832. The energy converter 820 comprises two Input terminais 821, 822 and two output terminais 823, 824. Of course, the energy converter 820 can operate in both directions, despite the connection terminais being described as input* or output* for the purposes of description only. The controlled switch 840 is for example driven by the control unit of the reconfigurable device 810, or by any control means of the power supply system. It makes it possible to connect the input terminais 821, 822 of the energy converter either to the connection terminais 811, 812 of the reconfigurable device 810, or to the connection terminais 831, 832 ofthe electric battery.

Of course, the invention is not limited to the examples which hâve just been described and nu mérous adjustments can be made to these examples without exceeding the scope of the invention. In addition, the different characteristics, forms, variants and embodiments described can be combined together ln various combinations inasmuch as they are not Incompatible or mutually exclusive.

Claims

1. A reconfigurable electrical energy storage device comprising:

• M x N storage modules (111-122), where M and N are strictly positive natural numbers, each storage module being capable of storing electrical energy by capacitive effect between a négative terminal and a positive terminal, contactors (131-140) arranged ln order to make It possible to connect by their terminais M, x N, storage modules, in different combinations, each combination denoted by an index I comprising Mj branches connected ln parallel, each branch comprising N, storage modules connected in sériés, where Mi x Ni < M x N, and • positive (102) and négative (101) electrical connection terminais to which are capable of being connected, ln each combination, the ends of the branches connected ln parallel.

2. The device according to claim 1, ln which the contactors (131-140) are controlled contactors.

3. The device according to one of claims 1 and 2, also comprising a safety contacter (1001) arranged in order to be able to adopt an isolation position, in which, for at least one combination of the storage modules (111-122), each branch (151-153) is Isolated from the positive electrical connection terminal (102) and/or from the négative electrical connection terminal (101).

4. The device according to claim 3, ln which the safety contacter (1001) Is a controlled contacter.

5. The device according to one of the preceding claims, in which the M x N storage modules (111-122) hâve one and the same maximum voltage Umod-max at their terminais and one and the same capacitance.

6. The device according to one of the preceding daims, in which the contactons (131-140) are arranged so that, for each combination, the product Mj x N_f of the number of branches times the number of storage modules in each branch Is equai to the number M x N of storage modules ln the reconfîgurable electrlcal energy storage device (100, 200, 810).

7. The device according to one of the preceding daims, in which the contactors (131-140) are arranged so that, among the different combinations, the maximum number N_max of storage modules ln each branch Is iess than or equai to three times the minimum number N_mi_n of storage modules ln each branch.

8. The device according to one of the preceding claims, together with daim 2, also comprising:

a measurement unit (201), arranged in order to measure a control voltage between the négative terminal of a first storage module among the M x N storage modules, and the positive terminal of a second storage module among the M x N storage modules, Identical to or different from the first storage module, and • a control unit (202), arranged ln order to drive the controlled contactors as a function of the control voltage.

9. The device according to claim 8, in which the control unit (202) Is arranged so that, when the control voltage becomes less than a minimum voltage U_min, or greater than a maximum voltage U_max, the controlled contactors (131-140) are drlven ln order to connect the storage modules (111-122) In a new combination, ln which the control voltage Is comprised between the minimum voltage U_mm, and the maximum voltage Umax.

10. The device according to claim 8, in which the control unit (202) is arranged so that:

when the control voltage becomes less than a minimum discharge voltage U_deCh, the controlled contactors (131-140) are driven ln order to connect the storage modules (111-122) in a new combination, in which the control voltage Is comprised between a minimum operating voltage U_mi_n, and a maximum operating voltage U_max, where U_dech < U_mm < U_max, and/or when the control voltage becomes greater than a maximum load voltage Uo,, the controlled contactera (131-140) are drlven in order to connect the storage modules (111-122) In a new combination, in which the control voltage is comprised between a minimum operating voltage U_mln, and a maximum operating voltage U_max, where U_m!n < U_max < U_ch.

11. The device according to one of claims 8 to 10, in which the measurement unit (201) Is arranged in order te measure the control voltage between the positive (102) and négative (101) electrlcal connection terminais of the configurable device (100, 200, 801).

12. The device according to daims 5 and 11, In which the control unit (202) and the storage modules (111-122) are arranged such that the voltage différence AU_max between the maximum operating voltage U_max and the minimum operating voltage U_m[f) is greater than or equal to the maximum voltage Umodm« at the terminais of a storage module.

13. The device according to claim 5 and one of claims 11 and 12, ln which the control unit (202) and the storage modules (111-122) are arranged so that the number of storage modules capable of being added or removed in each branch during swltch-over from one combination to a next combination is less than or equal to a maximum number η™βχ, determined so as to satisfy the relatlonshlp:

Ππιβχ Umod-max — AU_max — (nmax + 1) U_mdd._max where AU_max is the voltage différence between the maximum operating voltage U_max and the minimum operating voltage U_min between the positive (102) and négative (101) electrlcal connection terminais of the reconfigurable device.

14. A power supply system capable of supplying power for a load and being recharged by a recharging station, the system (800) comprising:

• a reconfigurable electrical energy storage device (100, 200, 810) according to one ofthe preceding claims, a third electrical connection terminal (411, 823) and a fourth electrical connection terminal (412, 824), capable of being connected to the load or to the recharglng station, and an energy converter (410, 820) capable of connecting the first and second electrical connection terminais to the third and the fourth electrical connection terminais, and arranged ln order to adapt the form of the voltage between the first and second electrical connection terminais to the form of the voltage between the third and the fourth electrical connection terminais.

15. The power supply system according to claim 14, comprising a device (200, 810) according to one of claims 9 to 13, in which the control unit (202) Is arranged so that, within the voltage range comprised between the minimum operating voltage U_mln and the maximum operating voltage U_maX(the energy converter (410, 820) has an efficiency greater than or equal to 95%.

16. The power supply system according to one of claims 14 and 15, also comprising:

• an electrochemical energy storage device by charge transfer (830), capable of storing electrical energy between a fifth electrical connection terminal (831) and a sixth electrical connection terminal (832), and a controlled switch (840) arranged ln order to connect the third and fourth electrical connection terminais to the first and second electrical connection terminais of the reconfigurable electrical energy storage device or to the fifth and sixth electrical connection terminais of the electrochemical energy storage device by charge transfer.

17. The power supply system according to one of claims 14 to 16, also comprising:

a generator unit, capable of delivering electrical energy between a seventh electrical connection terminal and an eighth electrical connection terminal, and a controlled switch arranged in order to connect the third and fourth electrical connection terminais to the first and second electrical connection terminais of the reconfigurable electrical energy storage device or to the seventh and eighth electrical connection terminais ofthe generator unit.

18. The power supply system according to claims 16 and 17, ln which the controlled switch (840) is arranged ln order to connect the third and fourth electrical connection terminais to the first and second electrical connection terminais of the reconfigurable electrical energy storage device (100, 200, 810), to the fifth and sixth electrical connection terminais of the electrochemical energy storage device by charge transfer (830) or to the seventh and eighth electrical connection terminais of the generator unit.

19. A vehicle comprising an electric power train and either a device according to one of claims 1 to 13, or a power supply system according to one of claims 14 to 18, the device or the power supply System being arranged ln order to supply the power train with electrical energy.