System for storing power by connecting batteries in parallel

Abstract

The invention relates to a system (1) for storing power by battery, which comprises: • at least two battery power storage units or DC power sources (2); • a DC power supply connection (3); • a switching arrangement (4) configured to be able to individually couple and decouple battery power storage units (2) to and from the DC power supply connection (3), and • a control supervisor (CALC) configured to select at least one of the storage units and to control the switching arrangement (4) in order to couple only the selected battery power storage units to the power supply connection, or several converters with several DC connections, the switching arrangement (4) having one switching cell (7) for each storage unit that has means for blocking the current or allowing it to pass therethrough that are reversible in their direction for blocking the current or allowing it to pass therethrough, and the control supervisor (CALC) being configured to be able to control the means for blocking the current or allowing it to pass therethrough.

Description

[0001] DESCRIPTION

[0002] TITLE: ENERGY STORAGE SYSTEM BY IMPLEMENTATION

[0003] PARALLEL BATTERIES

[0004] Technical field

[0005] The present invention relates to a battery energy storage system.

[0006] The present invention aims to constitute a system whose electronics allow the parallel connection of batteries for energy storage.

[0007] Previous techniques

[0008] Systems such as that described in the document WO2020192861 A1 are known, which allow the parallel use of a battery with a reversible DC / AC charger.

[0009] Switches controlled by a control unit allow the use of these batteries sequentially depending on their state of charge.

[0010] The disadvantage of this type of use is that the energy transfer is momentarily interrupted when one battery is discharged to switch to another battery.

[0011] Statement of the invention

[0012] The invention aims to overcome at least some of the aforementioned drawbacks and to propose a system allowing the use of several batteries in parallel with the same reversible charger on the one hand and on the other hand the possibility of assigning these batteries to different chargers.

[0013] In view of the above, the subject of the invention is a battery energy storage system, comprising at least two battery energy storage units, a DC power supply connection, a switching arrangement provided between said at least two battery energy storage units or DC power sources and the DC power supply connection, wherein the switching arrangement is configured to be able to individually couple and decouple each of the battery energy storage units or DC power sources to and from the DC power supply connection,and a control supervisor configured to select at least one of the battery energy storage units or DC energy sources and to control the switching arrangement to couple only the at least one selected battery energy storage unit or DC energy source to the DC power connection, the switching arrangement comprising a switching cell for each battery energy storage unit or DC energy source, each switching cell comprising current blocking or passing means, reversible in their current blocking or passing direction, and in that the control supervisor is configured to be able to control the current blocking or passing means to block or allow the current to flow in one direction or the other in said current blocking or passing means.,

[0014] Preferably, the means for blocking or passing current comprise an active switch.

[0015] For example, the active switch is of the MOSFET type.

[0016] Advantageously, the means for blocking or passing the current comprise a first diode connected in parallel with a first switch and a second diode connected in parallel with a second switch, the first diode and the second diode being mounted in series and head to tail with respect to each other, the control supervisor being configured to be able to individually switch each of said switches to the open or closed position.

[0017] According to one embodiment, the switches are of the IGBT type. Advantageously, the direct current power supply connection is linked to a first DC / AC converter itself linked to a public electricity supply network.

[0018] The system may further provide a second direct current connection linked on the one hand to a second DC / AC converter and on the other hand to each battery energy storage unit or direct current energy source via a switching cell for each battery energy storage unit or direct current energy source.

[0019] In one embodiment, the second direct current connection is connected on the one hand to a second DC / AC converter and on the other hand to a single battery energy storage unit or direct current energy source via a switching cell.

[0020] In one embodiment, the second DC connection is coupled to a second DC / AC converter itself coupled on the one hand to the first DC / AC converter and to each battery energy storage unit or DC energy source via a switching cell for each battery energy storage unit.

[0021] The invention also relates to a system in which at least one battery energy storage unit or direct current energy source is a vehicle battery.

[0022] Brief description of the drawings

[0023] The invention will be better understood from a detailed study of some embodiments taken as non-limiting examples and illustrated by the appended drawings, in which:

[0024] [Fig 1] shows a prior art battery energy storage system.

[0025] [Fig 2] represents the battery energy storage system according to a first embodiment, in which all the switches of the switching cells are open.

[0026] [Fig 3] represents a switching cell passing in a first direction.

[0027] [Fig 4] represents the switching cell of Figure 3, passing in a second direction opposite to the first direction.

[0028] [Fig 5] shows the battery energy storage system according to the first embodiment of Figure 2, in which two of the switches of the switching cells are closed.

[0029] [Fig 6] represents the battery energy storage system according to a second embodiment.

[0030] Detailed Description Figure 1 shows a prior art battery energy storage system comprising at least two, for example three, battery energy storage units 10, a direct current electrical connection 30 and a switching arrangement 40 provided between said at least two battery energy storage units or direct current energy sources 10 and the direct current electrical connection 30.

[0031] A control arrangement allows each of the battery energy storage units or DC energy sources 10 to be individually monitored, coupled, and decoupled from the DC electrical connection 30.

[0032] This prior art system aims to select one or more battery energy storage units or DC energy sources from the plurality of units or sources, such that a sum of short-circuit currents of the selected battery energy storage units or DC energy sources is less than a short-circuit current limit, which short-circuit current limit is less than a sum of short-circuit currents of said plurality of battery energy storage units or DC energy sources, and so as to connect only the selected battery energy storage units or DC energy sources to the DC power connection 30.

[0033] It is possible, for the invention, to replace each storage unit with a direct current energy source, for example a photovoltaic panel, or even with a supercapacitor so as to be able to respond to a possible large current demand.

[0034] This system does not allow several batteries to be assigned to different chargers, nor does it allow easy use of these batteries in parallel with the same reversible charger, since the batteries can only be connected in parallel over a restricted operating range limited by the battery with the lowest capacity.

[0035] The invention conversely aims at paralleling batteries at different charging voltages with a view to transferring energy, for example to the network or to a storage battery, by using power electronic components.

[0036] In the first embodiment of the invention illustrated in Figure 2, the battery energy storage system 1 comprises:

[0037] - at least two, for example three battery energy storage units or direct current energy sources 2;

[0038] - a direct current power connection 3;

[0039] - a switching arrangement 4 provided between said at least two battery energy storage units or DC energy sources 2 and the DC power connection 3, wherein the switching arrangement 4 is configured to be able to individually couple and decouple each of the battery energy storage units or DC energy sources 2 to and from the converter 5 via the DC power connection 3, and

[0040] - a control supervisor CALC configured to select at least one of the battery energy storage units or DC energy sources 2 and to control the switching arrangement 4 to couple only the at least two selected battery energy storage units or DC energy sources to and from the converter 5 through the DC power connection 30.

[0041] The switching arrangement 4 comprises a switching cell 7 for each battery energy storage unit or direct current energy source 2.

[0042] Each switching cell 7 comprises means for blocking or passing current 8A, 8B, 9A, 9B, shown in Figure 3

[0043] The current blocking or passage means 8A, 8B, 9A, 9B are reversible in their current blocking or passage direction.

[0044] The reversible switching cell 7 is made current-conducting in one direction or another or blocked by the switching elements 9A, 8A, 8B, 9B.

[0045] The control supervisor CALC is for example configured to select the at least one battery energy storage unit or DC energy sources 2 such that a sum of short-circuit currents of the at least one selected battery energy storage unit or DC energy source is less than a short-circuit current limit, wherein the short-circuit current limit is less than a sum of short-circuit currents of said at least two battery energy storage units or DC energy sources 2, and such that a sum of discharge powers or a sum of charge powers of the at least one selected battery energy storage unit or DC energy source is equal to or exceeds a power limit,and such that states of charge of the at least one selected battery energy storage unit or direct current energy source are within a determined range.,

[0046] The control supervisor CALC is configured to be able to control the current blocking or passage means 8A, 8B, 9A, 9B to block or authorize the passage of current in one direction or the other direction in said current blocking or passage means 8A, 8B, 9A, 9B.

[0047] Figure 2 illustrates a configuration in which all the switches of the cells 7 are open, said blocking or current passage means 8A, 8B, 9A, 9B therefore being blocking for the passage of current from and to the battery energy storage units or direct current energy sources 2 and the converter 5 through the direct current power connection 3.

[0048] The invention therefore consists of replacing each switch of the system described in document WO2020192861 A1 with an analog switching cell as described in Figures 3 and 4.

[0049] Figure 3 represents an exemplary embodiment of a switching cell 7 passing in a first direction, and Figure 4 represents the same switching cell, passing in a second direction opposite to the first direction.

[0050] The set of batteries or sources 2 selected to transfer energy to the network 6 is selected by each of the switches 9 of the switching cells 8B, 9B, the balancing of the battery voltage levels being done by natural conduction of the diode 8 of the switching cells 8A, 9A.

[0051] As long as the voltage of a battery or source 2 is not balanced with the others, diode 8 of cell 8A, 9A is blocked.

[0052] The reverse process applies in the case of a direction of circulation of the current from the converter 5 to the batteries 2.

[0053] The analog switching cell 7 comprises means for blocking or passing current 8A, 8B, 9A, 9B which comprise, for example, an active switch (not shown).

[0054] For example, the active switch is of the MOSFET type.

[0055] As an alternative to the active switch, the current blocking or passing means 8A, 8B, 9A, 9B comprise, as illustrated in Figures 3 and 4, a first diode 8A connected in parallel with a first switch 9A and a second diode 8B connected in parallel with a second switch 9A, the first diode 8A and the second diode 8B being connected in series and head to tail with respect to each other, that is to say in antiparallel with respect to each other, and a control supervisor CALC configured to be able to individually switch each of said switches 9A, 9B to the open or closed position.

[0056] Switches 9A, 9B respectively allow diodes DI and D2 to be short-circuited in order to control the flow of current in one direction or the other.

[0057] Diodes DI and D2, head to tail, prevent current from flowing in one direction or the other when switches 9A and 9B are open.

[0058] The switches 9A and 9B can be IGBT type switches, or the pairs 8A,9A and 8B,9B can be made up of a Mosfet type switch or any other active switch allowing the blocking or passage of current in one direction or the other.

[0059] According to one embodiment, at least one of the switches 9A, 9B is of the IGBT type. Advantageously, the direct current power supply connection 3 is linked to a first DC / AC converter 5 itself linked to a public electricity supply network 6.

[0060] As illustrated in Figure 5, at least one, for example two battery energy storage units or DC power sources 2 have one of their switching cells 7 closed, which allows the passage of current from said batteries or sources 2 to the electrical network 6, while the other battery energy storage units or DC power sources 2 (in this case the second of the at least two units 2 illustrated) has its two switching cells 7 open, which blocks any passage of current from and to these units.

[0061] The paralleling of the battery units or direct current energy sources 2 is thus achieved for the selective discharge of the battery units or direct current energy sources 2 in question, thanks to the control supervisor CALC which makes it possible to close the switches of each of the associated storage units or direct current energy sources 2 according to the need for use of these storage units or direct current energy sources 2, either to discharge them, or conversely for the transfer of current from the network 6 to these units or direct current energy sources 2 via the first DC / AC converter 5.

[0062] If units or sources 2 are of different load levels and therefore of different voltages, the one with the higher voltage will transfer its energy first through the first DC / AC converter 5, until the voltages of these units or sources 2 are balanced, which allows the two selected units or sources 2 in question to be used for the transfer of voltage by the first DC / AC converter 5 to the electrical network 6.

[0063] In fact, as long as the battery voltages are not balanced, the diodes of the switching cells 7 will prevent the higher voltage storage unit or direct current energy source 2 from transferring current to the lower voltage one. Thus, the CALC control supervisor can control the total discharge capacity of the system 1 by activating the cells 7 assigned to each of the units or sources 2.

[0064] Conversely, the charging of the storage units or direct current energy sources 2 by the network 6 is done by controlling the cells 7 allowing the current to pass in the opposite direction.

[0065] The advantages of this solution are the absence of risk of overcurrent from one storage unit or direct current energy source 2 to another, and the absence of current interruption to the network 6 when using several storage units or direct current energy sources 2.

[0066] The first DC / AC converter 5 can be connected to another converter, or to another electrical power source than a public electrical power supply network 6.

[0067] In fact, the energy storage system 1 allows the use of storage units or direct current energy sources with additional DC / AC reversible chargers 5B.

[0068] For example, in an embodiment illustrated by Figure 6, the system 1 comprises a second direct current connection linked on the one hand to a second DC / AC converter 5B and on the other hand to each battery energy storage unit or direct current energy source 2 via a switching cell 7 for each battery energy storage unit or direct current energy source 2.

[0069] Several additional 5B DC / AC reversible converters can be added in the same way.

[0070] Each unit or source 2 is then connected with as many switching cells 7 as there are converters.

[0071] The illustration gives the example of two converters 5, 5B located in the same storage system 1 or in two separate storage systems 1.

[0072] Thus the units or sources 2 can be used indifferently in parallel or not, and on each of the converters 5, 5B indifferently depending on the control supervisor CALC. For a given unit or source 2 and its switching cell 7, the converters 5, 5B are electrical chargers and the unit or source 2 is in recharge mode if its first switch 9A is passing and therefore closed and its second switch 9B open (Figure 3), while the converters 5, 5B and the unit or source 2 are in inverter mode (discharging the batteries into the network) if its first switch 9A is open and its second switch 9B is closed (Figure 4).

[0073] The system may further provide a second direct current connection linked on the one hand to a second DC / AC converter 5B and on the other hand to a single battery energy storage unit or direct current energy source 2 via a switching cell 7.

[0074] A battery unit or direct current energy source 2 is thus associated with several converters 5, 5B, which allows them to share the power to be transferred and therefore to minimize the heating of their electronics, or to increase this power to be transferred.

[0075] Thus, in such an embodiment, the direct current energy storage unit or source 2 is used by the two converters 5, 5B, while the other units or sources 2 are not used, the converters 5, 5B and the unit or source 2 are in recharge mode of the units or sources 2 if the first switch 9A of the switching cell 7 is closed, and are in inverter mode (electrical discharge of the units or sources in the network 6) if the second switch 9B of the switching cell 7 is closed.

[0076] The invention also relates to a system in which at least one battery energy storage unit or direct current energy source 2 is a vehicle battery.

[0077] This allows battery-electric vehicles to be used instead of battery storage units or DC energy sources 2 or to mix units or sources 2 serving as stationary battery stocks with battery-electric vehicles in parallel. This allows a charging station to be created capable of having a variable energy capacity depending on the presence or absence of vehicle batteries.

[0078] In another embodiment, the second direct current connection is coupled to the second DC / AC converter 5B which is itself coupled on the one hand to the first DC / AC converter 5 and to each battery energy storage unit or direct current energy source 2 via a switching cell 7 for each battery energy storage unit or direct current energy source 2.

[0079] The switching electronics thus produced also make it possible to charge or discharge the battery storage units or direct current energy sources 2 into each other without going through the electricity distribution network 7.

[0080] For a given fleet of electric vehicles, this variant of system 1 thus makes it possible to recharge a vehicle newly connected to this fleet independently of the connection to the electricity distribution network 7.

[0081] The invention therefore makes it possible to produce an energy storage system 1 comprising interface electronics between the battery storage units or direct current energy sources 2 and one or more communal converters 5, 5B serving as reversible chargers or inverters in order to parallel the storage units or direct current energy sources 2, which facilitates the increase in the energy storage capacity by the possibility of adding battery storage units or direct current energy sources without the need to add a converter. In addition, the batteries may be of a different nature (chemical composition, manufacturer, generation) or of the supercapacitor type, and may also be replaced by an energy production unit of the photovoltaic panel type, or combined with this source.

Claims

CLAIMS 1. Battery energy storage system (1), comprising: - at least two battery energy storage units or direct current energy sources (2); - a direct current power supply connection (3); - a switching arrangement (4) provided between said at least two battery energy storage units (2) and the DC power supply connection (3), wherein the switching arrangement (4) is configured to be able to individually couple and decouple each of the battery energy storage units or DC power sources (2) to and from the DC power supply connection (3), and - a control supervisor (CALC) configured to select at least one of the battery energy storage units or DC power sources (2) and to control the switching arrangement (4) to couple only the at least one selected battery energy storage unit to the DC power connection (30), characterized in that the switching arrangement (4) comprises a switching cell (7) for each battery energy storage unit or DC power source (2), each switching cell (7) comprising current blocking or passing means (8A, 8B, 9A, 9B), reversible in their current blocking or passing direction, and in that the control supervisor (CALC) is configured to be able to control the current blocking or passing means (8A, 8B, 9A,9B) to block or allow the passage of current in one direction or the other direction in said current blocking or passage means (8A, 8B, 9A, 9B)., 2. System (1) according to claim 1, wherein the direct current power supply connection (3) is linked to a first DC / AC converter (5) itself linked to a public electricity supply network (6).

3. System (1) according to any one of claims 1 and 2, further comprising a second direct current connection linked on the one hand to a second DC / AC converter (5B) and on the other hand to each battery energy storage unit or direct current energy source (2) via a switching cell (7) for each battery energy storage unit (2).

4. System (1) according to any one of claims 1 to 5. 3, further comprising a second direct current connection linked on the one hand to a second DC / AC converter (5B) and on the other hand to a single battery energy storage unit (2) via a switching cell (7).

5. System (1) according to any one of claims 1 to 5. 4, further comprising a second direct current connection coupled to a second DC / AC converter (5B) itself coupled on the one hand to the first DC / AC converter (5) and to each battery energy storage unit (2) via a switching cell (7) for each battery energy storage unit (2).

6. System (1) according to any one of claims 1 to 6. 5, wherein at least one battery energy storage unit (2) is a vehicle battery.

7. System (1) according to any one of claims 1 to 6, in which the means for blocking or passing the current (8A, 8B, 9A, 9B) comprise an active switch.

8. System (1) according to claim 7, in which the active switch is of the MOSFET type.

9. System (1) according to any one of claims 1 to 8, in which the current blocking or passing means (8A, 8B, 9A, 9B) comprise a first diode (8A) connected in parallel with a first switch (9A) and a second diode (8B) connected in parallel with a second switch (9A), the first diode (8A) and the second diode (8B) being connected in series and head to tail with respect to each other, the control supervisor (CALC) being configured to be able to individually switch each of said switches (9A, 9B) to the open or closed position.

10. System (1) according to claim 9, in which the switches (9A, 9B) are of the IGBT type.

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