POWER SUPPLY SYSTEM FOR MOBILITY VEHICLES

Abstract

The invention relates to an electrical interconnection device connected to a first battery (BAT1) and a second battery (BAT2), each providing the same input voltage (Ve), and connected to a battery charger delivering a charging voltage (Vch). This device comprises a DC / DC voltage converter (DC / DC#1) converting the voltage of the first battery (V1) into an output voltage (Vs) between a first (Bs1) and a second (Bs2) output terminal, connected respectively to a negative polarity terminal of the first battery and a positive polarity terminal of the second battery via a first switch (K1), and a connection device (Db) configured to provide a series or parallel connection of said two batteries (BAT1, BAT2).The device is characterized in that the connection device allows the batteries to be charged in parallel when the charging voltage is equal to the input voltage and to be charged in series when the charging voltage is equal to twice the input voltage, the first switch also being open when the charging voltage is equal to the input voltage. Figure for the abbreviation: Fig. 1.

Description

Title of the invention: POWER SUPPLY SYSTEM FOR MOBILITY VEHICLES Technical field of the invention

[0001] The present invention relates to an electrical interconnection device, an electrical power supply system and a mobility device comprising such an electrical power supply system.

[0002] The present invention also relates to a method of charging a first battery and a second battery both electrically connected to an electrical interconnection device according to the invention.

[0003] A mobility device is, for example, a motorized land vehicle, a train, an aircraft, or a drone. A motorized land vehicle is, for example, a car, a motorcycle, a motorized bicycle, or a motorized wheelchair.

[0004] The present invention can be applied in particular in the field of hybrid or electric motor vehicles. Technological background

[0005] A mobility device, for example an electric or hybrid vehicle, comprising an on-board network and an electrical power supply system comprising a first battery, a second battery, a first DC / DC voltage converter, a second DC / DC voltage converter and an electrical interconnection device, is known from the prior art.

[0006] In this power supply system, the outputs of the two DC / DC voltage converters are connected in parallel to provide an output voltage to power the on-board network, each of the two DC / DC voltage converters converting the voltage across one of the two batteries into the output voltage.

[0007] Furthermore, the electrical interconnection device connects the first and second batteries as well as the inputs of the two DC / DC voltage converters either in a parallel arrangement or in a series arrangement, for example depending on the value of a charging voltage delivered by a battery charger.

[0008] Such an electrical interconnection device allows the use of different types of chargers, i.e. having different charging voltages, to simultaneously charge the first and second batteries, while also allowing the on-board network to be powered during battery charging.

[0009] However, connecting the outputs in parallel and connecting the inputs of the two DC / DC voltage converters in series or parallel poses distribution problems of load between these two DC / DC voltage converters. Furthermore, the combined efficiency of these two converters is low.

[0010] It may therefore be desirable to provide an electrical interconnection device which makes it possible to overcome at least some of the aforementioned problems. Summary of the invention

[0011] According to a first aspect of the invention, an electrical interconnection device is therefore proposed for a power supply system of a mobility device, said electrical interconnection device being intended to be connected to a first battery and a second battery, each of said batteries providing the same input voltage, said electrical interconnection device being able to be connected to a battery charger delivering a charging voltage to said batteries, said interconnection device comprising: - a first isolation switch, - a first and a second output terminal, - a first DC / DC voltage converter intended to convert the voltage across the terminals of the first battery into an output voltage equal to twice the input voltage between the first and second output terminals, the first output terminal being intended to be electrically connected to a negative polarity terminal of the first battery, the second output terminal being intended to be connected to a positive polarity terminal of the second battery at least via the first isolation switch, - a connection device configured to provide a series or parallel connection of the two batteries, and - a control device for the connection device and the first isolation switch.

[0012] Said interconnecting device is characterized in that, when the batteries and the battery charger are connected to said electrical interconnecting device, the control device commands the connection device so that the battery charger charges the batteries in parallel when the charging voltage is equal to the input voltage and charges the batteries in series when the charging voltage is equal to twice the input voltage, said control device further commanding the first isolation switch to open when the charging voltage is equal to the input voltage.

[0013] This electrical interconnection device is remarkable in that, regardless of whether the two batteries are connected in series or parallel during charging, it is possible to obtain an output voltage between the first and second output terminals sufficient to power an on-board electrical system connected to these two batteries. output terminals without having to manage load balancing between two DC / DC voltage converters.

[0014] Indeed, when the two batteries are connected in series, the first isolation switch is closed so that the first output terminal is electrically connected to the negative terminal of the first battery and the second output terminal is electrically connected to the positive terminal of the second battery. Thus, the voltage across the two batteries in series is present at the terminals of the first and second output terminals, providing the output voltage. Furthermore, the output voltage is also provided by the conversion, by the first DC / DC voltage converter, of the input voltage across the terminals of the first battery.

[0015] Furthermore, when the two batteries are connected in parallel, the first isolation switch is opened so that the second battery is disconnected from the second output terminal and, in this parallel configuration, the output voltage is supplied only by the conversion, by the first DC / DC voltage converter, of the input voltage at the terminals of the first battery.

[0016] Thus, regardless of whether the two batteries are configured in series or parallel during charging, an output voltage is available to power an on-board network of the mobility vehicle.

[0017] Furthermore, the electrical interconnection device according to the invention does not use a set of two DC / DC converters whose outputs are put in parallel, which improves efficiency and eliminates the load balancing problem of electrical interconnection devices according to the prior art.

[0018] An electrical interconnection device according to the invention may further include one or more of the following optional features, taken individually or in any technically possible combination.

[0019] According to a first characteristic, the input voltage is a high voltage.

[0020] According to another characteristic, the output voltage is a high voltage.

[0021] According to another feature, the second input terminal is further connected electrically to the second output terminal via the series association of the fourth isolation switch and the first isolation switch.

[0022] According to another feature, the control device commands the first DC / DC voltage converter to convert the voltage across the terminals of the first battery into an output voltage equal to twice the input voltage between the first and second output terminals when the batteries and the battery charger are connected to the electrical interconnection device.

[0023] According to another feature, the electrical interconnection device further comprises: - a first and a second power supply terminal intended to be electrically connected respectively to a negative polarity terminal and a positive polarity terminal of the first battery, and - a third and a fourth power supply terminal intended to be electrically connected respectively to a negative polarity terminal and a positive polarity terminal of the second battery,

[0024] According to another feature, the connection device further comprises a first electrically connected connection switch between the second and third power supply terminals and a second electrically connected connection switch between the first and third power supply terminals.

[0025] According to another feature, the electrical interconnection device further comprises a second isolation transistor, a third isolation transistor, a fourth isolation transistor, a first input terminal and a second input terminal intended to be electrically connected to the battery charger to electrically connect the battery charger to the interconnection device, the first input terminal being further electrically connected to the first supply terminal via the second isolation switch, the second input terminal being further electrically connected to the fourth supply terminal via the series association of the third isolation switch and the fourth isolation switch.

[0026] According to another feature, the electrical interconnection device further includes a third electrically connected branch switch between the second and fourth power supply terminals.

[0027] According to another feature, the electrical interconnection device further includes a fifth isolation switch electrically connecting the first input terminal to the second supply terminal.

[0028] According to another feature, the electrical interconnection device further includes a second voltage converter in series with the first voltage converter so as to convert the output voltage into a low voltage.

[0029] According to another feature, at least one of the branch switches and / or at least one of the isolation switches is a relay.

[0030] According to another feature, at least one of the branch switches and / or at least one of the isolation switches is a transistor.

[0031] According to another feature, the first voltage converter is a boost converter.

[0032] According to a second aspect of the invention, a power supply system is also proposed comprising an electrical interconnection device according to the first aspect of the invention, a first battery and a second battery, said batteries being electrically connected to the electrical interconnection device such that the first output terminal is electrically connected to the negative polarity terminal of the first battery and the second output terminal is electrically connected to the positive polarity terminal of said second battery via the first switch.

[0033] According to a third aspect of the invention, a mobility device is also proposed comprising an electrical interconnection device according to the first aspect of the invention or a power supply system according to the second aspect of the invention.

[0034] According to a fourth aspect of the invention, a method for charging a first battery and a second battery electrically connected to an electrical interconnection device according to the first aspect of the invention is also proposed, this method comprising: - a step involving connecting a battery charger to the electrical interconnection device, - a step to detect the battery charger's charging voltage, - when the charging voltage is equal to twice the input voltage, a step of controlling the connection device so that the battery charger charges the batteries in series, and - when said charging voltage is equal to the input voltage, a control step to the opening of the first switch and a control step of the connection device so that the battery charger charges the batteries in parallel. Brief description of the figures

[0035] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which: - Figure [1] is an electrical diagram of a first embodiment of an electrical power supply system according to the invention, - [Fig.2] is a flowchart representing an example of a charging process for a first battery and a second battery using the power supply system of [Fig.1], - Figure 3 is an electrical diagram of a second embodiment of a power supply system according to the invention, and - [Fig.4] is a flowchart representing an example of a charging process for a first battery and a second battery using the power supply system of [Fig.3]. Detailed description of the invention

[0036] With reference to [Fig. 1], a first embodiment of an electrical power supply system SA intended to equip, for example, an electric vehicle will now be described.

[0037] The power supply system SA comprises, firstly, a first battery BATI generating a first input voltage VI and a second battery BAT2 generating a second input voltage V2, the second input voltage VI being equal to the first input voltage V2. In other words, the first and second batteries generate the same input voltage Ve. In the example described here, the input voltage Ve is equal to 400V, i.e., a high voltage. By "high voltage" is meant a voltage greater than 100V, preferably greater than or equal to 200V. Conversely, a "low voltage" is a voltage less than 100V, preferably less than 60V.

[0038] In the example described here, each of the Batl, Bat2 batteries comprises three cells or accumulators in series. For example, the cells are lithium-ion cells, or lithium-iron-phosphate cells (LFP cells), or lithium-nickel-manganese-cobalt cells (NMC cells).

[0039] The SA power supply system also includes an electrical interconnection device AE. This electrical interconnection device AE includes: - a first power supply terminal Bal and a second power supply terminal Ba2 electrically connected respectively to a negative polarity terminal and a positive polarity terminal of the first battery BATI, and - a third power supply terminal Ba3 and a fourth power supply terminal Ba4 electrically connected respectively to a negative polarity terminal and a positive polarity terminal of the second battery BAT2. - a Db connection device configured to provide a series or parallel connection of the two batteries BATI and BAT2, - a first isolation switch K1, a second isolation switch K2 and a third isolation switch K3, - a first Bsl and a second Bs2 output terminal, the first output terminal Bsl being electrically connected to a negative polarity terminal of the first battery BATI via the second isolation switch K2, the second output terminal Bs2 being connected to a positive polarity terminal of the second battery BAT2 via the series connection of the first isolation switch Kl and the third isolation switch K3, and - a first DC- input terminal and a second DC+ input terminal intended to be connected to a battery charger or charging station, the first DC- input terminal being electrically connected to the first Bal power supply terminal via the second isolation switch K2.

[0040] In this first embodiment, the electrical interconnection device AE further includes a fourth isolation switch K4 and a fifth isolation transistor K5.

[0041] The fourth isolation transistor K4 and the fifth isolation transistor K5 allow the second DC+ input terminal to be electrically connected respectively to the fourth supply terminal Ba4 via the third isolation switch K3 and to the second supply terminal Ba2.

[0042] In addition, the second DC+ input terminal is electrically connected to the second Bs2 output terminal via the series connection of the fourth isolation transistor K4 and the first isolation transistor Kl.

[0043] In this first embodiment, the branching device Db includes a first branching switch Kbl electrically connected between the second power supply terminal Ba2 and the third power supply terminal Ba3 and a second branching switch Kb2 electrically connected between the first power supply terminal Bal and the third power supply terminal Ba3.

[0044] In the example described here, the isolation switches and the branch switches of the branching device Db are made by mechanical relays.

[0045] Alternatively, the isolation switches and the branch switches of the branching device Db are for example made by transistor switches such as metal-oxide gate field-effect transistors, generally referred to by the acronym MOSFET (from the English "Metal Oxide Semiconductor Field Effect Transistor").

[0046] Alternatively, these transistor switches can be IGBT (Insulated-Gate Bipolar Transistor) type transistors or FET (Field-effect transistor) type transistors made of gallium nitride (GaN-FET), or HEMT (high-electron-mobility transistor) type transistors, for example made of gallium nitride.

[0047] In yet another variant, some of the switches in the group comprising the isolation switches and the branch switches of the branching device Db are made by mechanical relays while the others are made by transistor switches.

[0048] The electrical interconnection device AE also includes a first DC / DC voltage converter#1 converting the input voltage Ve present between the first power supply terminal Bal and the second power supply terminal Ba2 into an output voltage Vs present between the first output terminal Bsl and the second output terminal Bs2, said output voltage Vs being equal to twice the input voltage Ve so that in the example described here, the output voltage Vs is equal to 800V.

[0049] In the example described here, the first DC / DC voltage converter#1 is a boost converter since the output voltage Vs is higher than the input voltage Ve. This boost converter includes a switching arm comprising a high-side switch Hs and a low-side switch Ls connected together at a midpoint. The high-side switch Hs is also connected to the second output terminal Bs2, while the low-side switch Ls is connected to the first output terminal Bsl.

[0050] The high side switch Hs and the low side switch Ls are for example made by transistor switches, such as MOSFETs, IGBTs or FET or HEMT type transistors.

[0051] The boost chopper also includes an inductance L connected between the midpoint and the second supply terminal Ba2.

[0052] In the example described, the first DC / DC voltage converter#1 has a power between 500W and 1.5kW, for example 1kW and an efficiency of 95%.

[0053] The electrical interconnection device AE may also include a second DC / DC#2 voltage converter in series with the DC / DC#1 voltage converter so as to convert the output voltage Vs into a low voltage Vbs, for example 12V.

[0054] In the example described, the second DC / DC voltage converter#2 has a power output between 2kW and 4kW, for example 3kW, and an efficiency of 98%. In this example, the efficiency of the series connection of the two DC / DC converters is 93%.

[0055] Finally, the electrical interconnection device AE also includes a control device Dco for the isolation switches, the branch switches of the branching device, the first DC / DC#1 voltage converter and, if present, the second DC / DC#2 voltage converter.

[0056] Thus, in the example described here, the control device Dco alternately controls the opening of the high side switch Hs and the low side switch Ls of the boost chopper so as to convert the input voltage Ve present between the two terminals of the battery BATI into the output voltage Vs according to a control method known to the person skilled in the art and which will not be described further here.

[0057] Preferably, the Dco control device includes a system for managing and / or balancing the cells of the BATI and BAT2 batteries.

[0058] With reference to [Fig.2], a method of charging E of the first battery BATI and the second battery BAT 2 using the power supply system SA will now be described.

[0059] Prior to the execution of this charging method, it is assumed that the first battery BATI and the second battery BAT2 are electrically connected in series via the connection device Db. In other words, it is assumed that the first connection switch Kbl is closed and that the second connection switch Kb2 is open.

[0060] It is also assumed that the first isolation switch K1, the second isolation switch K2 and the third isolation switch K3 are closed while the fourth isolation switch K4 and the fifth isolation switch K5 are open.

[0061] During a step E10, a battery charger Cb is connected to the electrical interconnection device AE. More specifically, a plug of the battery charger Cb is connected to the first DC- input terminal and the second DC+ input terminal to provide a charging voltage Vch between these two terminals.

[0062] During an E20 step, the Dco control device detects the charging voltage Vch of the battery charger Cb.

[0063] During an E30 step, the control device Dco compares the load voltage Vch to the input voltage Ve.

[0064] If the load voltage Vch is equal to the input voltage Ve, the control device Dco proceeds to step E90.

[0065] If the charging voltage Vch is not equal to the input voltage Ve, the control device Dco, during a step E60, compares the charging voltage Vch to twice the input voltage Ve.

[0066] If the charging voltage Vch is not equal to twice the input voltage Ve, the charging process terminates.

[0067] If the charging voltage Vch is equal to twice the input voltage Ve, during a step E70, the control device Dco commands the fourth isolation switch K4 to close and the fifth isolation switch K5 to open, thus allowing the two batteries BATI, BAT2 to be charged in series by the battery charger Cb, then, after the charging of the two batteries, the control device Dco, during a step E80, commands the fourth isolation switch K4 to open and keeps the fifth isolation switch K5 closed and the charging process ends.

[0068] During step E90, the control device Dco commands the second isolation switch K2 and the third isolation switch K3 to open.

[0069] During step E100, the control device Dco commands the connection device Db so that the two batteries BATI and BAT2 are electrically connected in parallel, ensuring that the charging voltage Vch delivered by the battery charger Cb is applied simultaneously to the terminals of each of the two batteries. To electrically connect the two batteries BATI and BAT2 in parallel, the control device Dco opens the first connection switch Kbl and closes the second connection switch Kb2.

[0070] During a step El 10, the control device Dco commands the first isolation switch Kl to open.

[0071] During an E120 step, the control device Dco commands the second isolation switch K2 and the third isolation switch K3 to close.

[0072] During a step E130, the control device Dco commands the fourth isolation switch K4 and the fifth isolation switch K5 to close, thus allowing the two batteries BATI, BAT2 to be charged by the battery charger Cb.

[0073] . After the two batteries have been charged, the Dco control device, during a step E140, command to open the fourth isolation switch K4 and the fifth isolation switch K5.

[0074] During an E150 step, the Dco control device commands the second isolation switch K2 and the third isolation switch K3 to open.

[0075] During step E160, the control device Dco commands the connection device Db so that the two batteries BATI and BAT2 are electrically connected in series. To electrically connect the two batteries in series, the control device Dco closes the first connection switch Kbl and opens the second connection switch Kb2.

[0076] During an E170 step, the Dco control device commands the second isolation switch K2 and the third isolation switch K3 to close.

[0077] During an E180 step, the control device Dco commands the first isolation switch Kl to close, then the charging process stops.

[0078] We will now describe an electrical power supply system SA' intended to equip, for example, an electric vehicle in a second embodiment of the invention.

[0079] Common and identical elements of the previously described SA power supply system shall be designated by the same reference signs.

[0080] The SA' power supply system differs from the SA electrical system by its AE' electrical interconnection device, which we will now describe with reference to [Fig.3].

[0081] The electrical interconnection device AE' includes a branching device DB' which, like the branching device DB, includes the first branching switch Kbl electrically connected between the second power supply terminal Ba2 and the third power supply terminal Ba3 and the second branching switch Kb2 electrically connected between the first power supply terminal Bal and the third power supply terminal Ba3.

[0082] In this second embodiment, this DB' branching device further includes a third branching switch Kb3 electrically connected between the second power supply terminal Ba2 and the fourth power supply terminal Ba4.

[0083] Furthermore, in this second embodiment, the electrical interconnection device AE' does not include a fifth isolation switch K5 electrically connecting the second DC+ input terminal to the second supply terminal Ba2.

[0084] Finally, in this second embodiment, the control device Dco' controls the isolation switches, the branch switches of the branching device DB', the first DC / DC#1 voltage converter and, if present, the second DC / DC#2 voltage converter.

[0085] With reference to [Fig.4], a method of charging F of the first battery and the second battery using the power supply system SA' will now be described.

[0086] Prior to the execution of this charging method F, it is assumed that the first battery BATI and the second battery BAT2 are electrically connected in series via the connection device Db'. In other words, it is assumed that the first connection switch Kbl is closed and that the second connection switch Kb2 is open.

[0087] It is also assumed that the first isolation switch K1, the second isolation switch K2 and the third isolation switch K3 are closed while the fourth isolation switch K4 is open.

[0088] This charging method differs first of all from that of [Fig.2] in that the control of the various switches of the electrical supply system SA' is done by the control device Dco' and not by the control device Dco.

[0089] Next, when the charging voltage Vch is equal to twice the input voltage Ve, the charging process F differs from that of [Fig.2] by the steps F70 and F80 which respectively replace the steps E70 and E80.

[0090] Thus, if the charging voltage Vch is equal to twice the input voltage Ve, during a step F70, the control device Dco' commands the fourth isolation switch K4 to close, thus allowing the parallel charging of the two batteries BATI, BAT2 by the battery charger Cb, then, at the end of the charge of the two batteries, the Dco' control device, during a step F80, commands the fourth isolation switch K4 to open.

[0091] Similarly, if the charging voltage Vch is equal to the input voltage Ve, the charging process F differs from that of [Fig.2] by the steps F100, F130, F140 and F160 which respectively replace the steps E100, E130, E140 and E160.

[0092] During step F100, the control device Dco' commands the connection device Db' so that the two batteries BATI and BAT2 are electrically connected in parallel, ensuring that the charging voltage Vch delivered by the battery charger Cb is applied simultaneously to the terminals of each of the two batteries. To electrically connect the two batteries BATI and BAT2 in parallel, the control device Dco' opens the first connection switch Kbl and closes the second connection switch Kb2 and the third connection switch Kb3.

[0093] During step F130, the control device Dco commands the fourth isolation switch K4 to close, thus allowing the parallel charging of the two batteries BATI, BAT2 by the battery charger Cb.

[0094] . After the two batteries have been charged, the Dco control device, during Step F140, commands the opening of the fourth isolation switch K4.

[0095] During step F160, the control device Dco commands the connection device Db so that the two batteries BATI and BAT2 are electrically connected in series. To electrically connect the two batteries in series, the control device Dco closes the first connection switch Kbl and opens the second connection switch Kb2 and the third connection switch Kb3.

[0096] It should also be noted that the invention is not limited to the embodiments described above. It will indeed be apparent to those skilled in the art that various modifications can be made to the embodiments described above, in light of the information just disclosed to them.

[0097] For example, the electrical power supply systems and electrical interconnection devices described above can be fitted to mobility devices other than electric vehicles.

[0098] In the detailed presentation of the invention given above, the terms used shall not be interpreted as limiting the invention to the embodiments set forth in this description, but shall be interpreted as including all equivalents which can be foreseen by a person skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

1. Demands Electrical interconnection device (AE, AE') for an electrical power supply system (SA, SA') of a mobility device, said electrical interconnection device (AE, AE') being intended to be connected to a first battery (BATI) and a second battery (BAT2), each of said batteries (BATI, BAT2) providing the same input voltage (Ve), said electrical interconnection device (AE, AE') being able to be connected to a battery charger delivering a charging voltage (Vch) to said batteries, said interconnection device (AE, AE') comprising: - a first isolation switch (Kl), - a first (Bsl) and a second (Bs2) output terminal, - a first DC / DC voltage converter (DC / DC#1) intended to convert the voltage across the terminals of the first battery (Ve) into an output voltage (Vs) equal to twice the input voltage (Ve) between the first (Bsl) and the second (Bs2) output terminal, the first output terminal being intended to be electrically connected to a negative polarity terminal of the first battery (BATI), the second output terminal being intended to be connected to a positive polarity terminal of the second battery (BAT2) at least via the first isolation switch (Kl), - a connection device (Db, Db') configured to provide a series connection or a parallel connection of the two batteries (BATI, BAT2), and - a control device (Dco, Dco') for the connection device (Db, Db') and the first isolation switch (Kl), said interconnecting device (Db, Db') being characterized in that, when the batteries (BATI, BAT2) and the battery charger are connected to said electrical interconnecting device (AE, AE'), the control device (Dco, Dco') commands the connection device (Db, Db') so that the battery charger charges the batteries (BATI, BAT2) in parallel when the charging voltage (Vch) is equal to the input voltage (Ve) and charges the batteries (BATI, BAT2) in series when the load voltage (Vch) is equal to twice the input voltage (Ve), said control device further commanding the first isolation switch (Kl) to open when the load voltage (Vch) is equal to the input voltage (Ve).

2. Electrical interconnection device (AE, AE') according to the preceding claim wherein the control device (Dco, Dco') commands the first DC / DC voltage converter (DC / DC#1) to convert the voltage across the terminals of the first battery (Ve) into an output voltage (Vs) equal to twice the input voltage (Ve) between the first (Bs1) and second (Bs2) output terminals when the batteries (BATI, BAT2) and the battery charger are connected to said electrical interconnection device (AE, AE').

3. Electrical interconnection device (AE, AE') according to any one of the preceding claims further comprising: - a first (Bal) and a second power supply terminal (Ba2) intended to be electrically connected respectively to a negative polarity terminal and a positive polarity terminal of the first battery (BATI), and - a third (Ba3) and a fourth power supply terminal (Ba4) intended to be electrically connected respectively to a negative polarity terminal and a positive polarity terminal of the second battery (BAT2), and wherein said connection device (Db, Db') comprises a first connection switch (Kbl) electrically connected between the second (Ba2) and the third power supply terminal (Ba3) and a second connection switch (Kb2) electrically connected between the first (Bal) and the third power supply terminal (Ba3).

4. An electrical interconnection device (AE, AE') according to the preceding claim, further comprising a second isolation transistor (K2), a third isolation transistor (K3), a fourth isolation transistor (K4), a first input terminal (DC-) and a second input terminal (DC+) for electrically connecting said battery charger to electrically connect said battery charger to said device interconnection (AE, AE'), the first input terminal (DC-) being further electrically connected to the first supply terminal (Bal) via the second isolation switch (K2), the second input terminal (DC+) being further electrically connected to the fourth supply terminal (Ba4) via the series association of the third isolation switch (K3) and the fourth isolation switch (K4).

5. Electrical interconnection device (AE, AE') according to any one of claims 3 to 4 comprising a third branch switch (Kb3) electrically connected between the second (Ba2) and fourth supply terminal (Ba4).

6. Electrical interconnection device (AE) according to claim 4 further comprising a fifth isolation switch (K5) electrically connecting the first input terminal (DC-) to the second supply terminal (Ba2).

7. Electrical interconnection device (AE') according to any one of the preceding claims further comprising a second voltage converter (DC / DC#2) in series with the first DC / DC voltage converter (DC / DC#1) so as to convert the output voltage (Vs) into a low voltage (Vbs).

8. Electrical interconnection device (AE') according to any one of claims 3 to 7 wherein at least one of the branch switches and / or at least one of the isolation switches is a relay.

9. Electrical interconnection device (AE') according to any one of claims 3 to 8 wherein at least one of the branch switches and / or at least one of the isolation switches is a transistor.

10. Electrical interconnection device (AE') according to any one of the preceding claims wherein the first voltage converter (DC / DC# 1) is a boost chopper.

11. Power supply system (SA, SA') comprising an electrical interconnection device (AE, AE') according to any one of claims 1 to 10, a first battery (BATI) and a second battery (BAT2), said batteries (BATI, BAT2) being electrically connected to said electrical interconnection device such that the first output terminal (Bsl) is electrically connected to the negative polarity terminal of the first battery (BATI) and that the second output terminal (Bs2) is electrically connected to the positive polarity terminal of said second battery (BAT2) via the first switch (Kl).

12. Mobility device, for example a vehicle, comprising an electrical power supply system (SA, SA') according to claim 11 or an electrical interconnection device (AE, AE') according to any one of claims 1 to 10.

13. A method for charging (E, F) a first battery (BATI) and a second battery (BAT2) electrically connected to an electrical interconnection device (AE, AE') according to any one of claims 1 to 10, said method comprising: - a connection step (E10) of a battery charger to said electrical interconnection device (AE, AE'), - a detection step (E20) of the charging voltage of said battery charger, - when said charging voltage (Vch) is equal to twice the input voltage (Ve), a control step (E70, F70) of the connection device (Db, Db') so that said battery charger charges said batteries (BATI, BAT2) in series, and - when said charging voltage (Vch) is equal to the input voltage (Ve), a control step to the opening (El 10) of the first switch (Kl) and a control step (E100, F100) of the connection device (Db, Db') so that said battery charger charges said batteries (BATI, BAT2) in parallel.

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