ENERGY STORAGE SYSTEM BY PARALLELING BATTERIES

Abstract

This battery energy storage system (1) comprises: - at least two battery energy storage units or direct current energy sources (2); - a direct current power supply connection (3);- a switching arrangement (4) configured to be able to individually couple and disconnect battery energy storage units (2) to and from the DC power connection (3), and - a control supervisor (CALC) configured to select at least one of the storage units and to control the switching arrangement (4) to couple only the selected battery energy storage units to the power connection, or several converters with several DC connections, the switching arrangement (4) comprising a switching cell (7) for each storage unit having current blocking or passing means (8A, 8B, 9A, 9B), reversible in their current blocking or passing direction, and the control supervisor (CALC) being configured to be able to control the current blocking or passing means (8A, 8B, 9A, 9B). Figure for the abstract: [Fig 6];

Description

Title of the invention: ENERGY STORAGE SYSTEM BY PARALLEL BATTERIES technical field

[0001] The present invention relates to a battery energy storage system.

[0002] The present invention aims to constitute a system whose electronics allow the implementation in parallel with batteries for energy storage. Previous techniques

[0003] Systems such as the one described in document WO2020192861A1 are known, which allow the parallel use of a battery with a reversible DC / AC charger.

[0004] Switches controlled by a control unit allow the use of these batteries sequentially according to their state of charge.

[0005] The disadvantage of this type of use is that the transfer of energy is momentarily interrupted when one battery is discharged in order to switch to another battery. Description of the invention

[0006] The invention aims to overcome at least some of the aforementioned drawbacks and to provide 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.

[0007] In view of the foregoing, the invention relates to 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 power sources and to control the switching arrangement to couple only the at least one selected battery energy storage unit or DC power source to the DC power connection,

[0008] the switching arrangement comprising a switching cell for each battery energy storage unit or direct current energy source, each switching cell comprising means for blocking or passing current, reversible in their direction of blocking or passing current, and in that the control supervisor is configured to be able to control the means for blocking or passing current to block or allow the passage of current in one direction or the other in said means for blocking or passing current.

[0009] Preferably, the means for blocking or passing the current include an active switch.

[0010] For example, the active switch is of the MOSFET type.

[0011] Advantageously, the means for blocking or passing 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 back-to-back 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.

[0012] According to one embodiment, the switches are of the IGBT type.

[0013] Advantageously, the DC power supply connection is linked to a first DC / AC converter itself linked to a public power supply network.

[0014] 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.

[0015] In one embodiment, the second DC connection is linked on the one hand to a second DC / AC converter and on the other hand to a single battery energy storage unit or DC energy source via a switching cell.

[0016] In one embodiment, the second DC connection is coupled to a second DC / AC converter which is 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.

[0017] 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. Brief description of the drawings

[0018] The invention will be better understood upon a detailed study of some embodiments taken by way of non-limiting examples and illustrated by the accompanying drawings, in which:

[0019] [Fig. 1] represents a prior art battery energy storage system.

[0020] [Fig.2] represents the battery energy storage system according to a first embodiment, in which all switches of the switching cells are open.

[0021] [Fig.3] represents a switching cell that passes in the first direction.

[0022] [Fig.4] represents the switching cell of [Fig.3], passing through a second opposite meaning to the first meaning.

[0023] [Fig.5] represents the battery energy storage system according to the first embodiment of [Fig.2], in which two of the switches of the switching cells are closed.

[0024] [Fig.6] represents the battery energy storage system according to a second method of implementation. Detailed description

[0025] Fig. 1 represents a prior art battery energy storage system comprising at least two, for example three battery energy storage units 10, a DC electrical connection 30 and a switching arrangement 40 provided between said at least two battery energy storage units or DC energy sources 10 and the DC electrical connection 30.

[0026] A control arrangement allows each of the battery energy storage units or DC power sources 10 to be monitored, coupled and decoupled individually from the DC electrical connection 30.

[0027] This prior art system aims to select one or more battery energy storage units or DC power sources from among the plurality of units or sources, such that a sum of short-circuit currents of the selected battery energy storage units or DC power 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 power sources, and in such a way as to connect only the selected battery energy storage units or DC power sources to the DC power supply connection 30.

[0028] For the invention, it is possible to replace each storage unit with a direct current energy source, for example a photovoltaic panel, or again by a supercapacitor so as to be able to respond to a possible large current demand.

[0029] This system does not allow several batteries to be assigned to different chargers, nor the easy use of these batteries in parallel with the same reversible charger, since the parallel connection of the batteries can only be done over a restricted operating range limited by the battery with the lowest capacity.

[0030] The invention aims, conversely, at putting batteries at different charging voltages in parallel in order to transfer energy, for example to the network or to a storage battery, by using power electronics components.

[0031] In the first embodiment of the invention illustrated in [Fig.2], the battery energy storage system 1 comprises:

[0032] - at least two, for example three battery energy storage units or direct current energy sources 2;

[0033] - a DC power supply connection 3;

[0034] - a switching arrangement 4 provided between said at least two units battery energy storage or DC power sources 2 and the DC power supply connection 3,

[0035] wherein the switching arrangement 4 is configured to be able to individually couple and disconnect each of the battery energy storage units or DC power sources 2 to and from the converter 5 via the DC power supply connection 3, and

[0036] - a CALC command supervisor 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 two selected battery energy storage units or DC power sources to and from the converter 5 by the DC power connection 30.

[0037] The switching arrangement 4 includes a switching cell 7 for each battery energy storage unit or DC power source 2.

[0038] Each switching cell 7 includes means for blocking or passing current 8A,8B,9A,9B, shown [Fig.3]

[0039] The means for blocking or passing current 8A,8B,9A,9B are reversible in their direction of blocking or passing current.

[0040] The reversible switching cell 7 is made current-conducting in one direction or blocked by the switching elements 9A, 8A, 8B, 9B.

[0041] The CALC control supervisor is, for example, configured to select at least one battery energy storage unit or current energy sources continuous 2 such that a sum of short-circuit currents of at least one selected battery energy storage unit or DC energy source is less than a short-circuit current limit, in which the short-circuit current limit is less than a sum of short-circuit currents of said at least two selected battery energy storage units or DC energy sources 2, and such that a sum of discharge powers or a sum of charge powers of 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 at least one selected battery energy storage unit or DC energy source are within a specified range.

[0042] The CALC control supervisor 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 in said current blocking or passing means 8A,8B,9A,9B.

[0043] Figure 2 illustrates a configuration in which all the cell switches 7 are open, the said means of blocking or passing current 8A,8B,9A,9B being therefore blocking the passage of current from and to the battery energy storage units or DC power sources 2 and the converter 5 through the DC power connection 3.

[0044] The invention therefore consists of replacing each switch of the system described in document WO2020192861A1 with an analog switching cell as described in Figures 3 and 4.

[0045] Fig. 3 represents an example of an embodiment of a switching cell 7 that conducts in a first direction, and Fig. 4 represents the same switching cell, conducting in a second direction opposite to the first direction.

[0046] 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.

[0047] As long as the voltage of a battery or source 2 is not balanced with the others, the diode 8 of cell 8A, 9A is blocked.

[0048] The reverse process applies in the case of a direction of current flow from the converter 5 to the batteries 2.

[0049] The analog switching cell 7 includes means for blocking or passing current 8A,8B,9A,9B which include for example an active switch (not illustrated).

[0050] For example, the active switch is of the MOSFET type.

[0051] As an alternative to the active switch, the means for blocking or passing current 8A,8B,9A,9B comprise, as illustrated by 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 mounted in series and back-to-back with respect to each other, i.e. in antiparallel with respect to each other, and a CALC control supervisor configured to be able to individually switch each of said switches 9A,9B in the open or closed position.

[0052] Switches 9A, 9B allow respectively to short-circuit diodes DI and D2 in order to control the flow of current to go in one direction or the other.

[0053] The back-to-back diodes DI and D2 prevent the current from flowing in either direction when switches 9A and 9B are open.

[0054] 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.

[0055] According to one embodiment, at least one of the switches 9A,9B is of type IGBT.

[0056] Advantageously, the DC power supply connection 3 is linked to a first DC / AC converter 5 itself linked to a public power supply network 6.

[0057] As illustrated by [Fig.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 current to flow 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) have both of its switching cells 7 open, which blocks any current flow from and to these units.

[0058] The parallel connection of the battery units or DC power sources 2 is thus achieved for the selective discharge of the battery units or DC power sources 2 in question, thanks to the CALC control supervisor which allows the switches of each of the associated storage units or DC power sources 2 to be closed according to the need for use of these storage units or DC power sources 2, either to discharge them, or conversely for the transfer of current from the network 6 to these units or DC power sources 2 via the first DC / AC converter 5.

[0059] If units or sources 2 are of different charge levels and therefore 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 voltage transfer through the first DC / AC converter 5 to the electrical network 6.

[0060] Indeed, as long as the battery voltages are not balanced, the diodes of the switching cells 7 will prevent the higher voltage storage unit or DC power source 2 from transferring current to the lower voltage one.

[0061] Thus the CALC control supervisor can control the total discharge capacity of system 1 by activating the cells 7 assigned to each of the units or sources 2.

[0062] 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 reverse direction.

[0063] 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.

[0064] The first DC / AC converter 5 can be connected to another converter, or to another power supply source than a public power supply network 6.

[0065] Indeed, the energy storage system 1 allows the use of the storage units or direct current energy sources with additional DC / AC reversible chargers 5B.

[0066] For example, in an embodiment illustrated by [Fig.6], the system 1 includes a second DC 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 DC power source 2 via a switching cell 7 for each battery energy storage unit or DC power source 2.

[0067] Several additional 5B DC / AC reversible converters can be added in the same way.

[0068] Each unit or source 2 is then connected with as many switching cells 7 as there are converters.

[0069] The illustration gives the example of two converters 5, 5B located in the same storage system 1 or in two separate storage systems 1.

[0070] 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 CALC control supervisor.

[0071] For a given unit or source 2 and its switching cell 7, the converters 5.5B are electric chargers and the unit or source 2 is in charging mode if its first switch 9A is conducting, therefore closed, and its second switch 9B is open ([Fig.3]), whereas the converters 5.5B and the unit or source 2 are in inverter mode (discharging batteries into the network) if its first switch 9A is open and its second switch 9B is closed ([Fig.4]).

[0072] 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.

[0073] A battery unit or direct current power source 2 is thus associated with several converters 5.5B, which allows them to share the power to be transferred and thus minimize the heating of their electronics, or increase this power to be transferred.

[0074] Thus, in such an embodiment, the DC storage unit or energy 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 charge 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 into the network 6) if the second switch 9B of the switching cell 7 is closed.

[0075] 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.

[0076] This allows battery electric vehicles to be put in place of battery storage units or direct current energy sources 2 or to make a mix between units or sources 2 serving as stationary battery storage with battery electric vehicles in parallel.

[0077] Thus, a charging station can be made capable of having a variable energy capacity depending on the presence or absence of vehicle batteries.

[0078] In another embodiment, the second DC 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 DC power source 2 via a switching cell 7 for each battery energy storage unit or DC power source 2.

[0079] The switching electronics thus produced also allows the battery storage units or direct current energy sources 2 to be charged or discharged 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 thus makes it possible to implement an energy storage system 1 comprising interface electronics between battery storage units or direct current energy sources 2 and one or more shared converters 5, 5B serving as reversible chargers or inverters in order to connect the storage units or direct current energy sources 2 in parallel, which facilitates increasing the energy storage capacity by allowing the addition of battery storage units or direct current energy sources without the need for an additional converter. Furthermore, the batteries can be of different types (chemical composition, manufacturer, generation) or of the supercapacitor type, and can also be replaced by a photovoltaic panel-type energy production unit, or combined with this source.

Claims

Demands

1. Battery energy storage system (1), comprising: - at least two battery energy storage units or DC power sources (2); - a DC 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 supply 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 passage means (8A, 8B, 9A, 9B), reversible in their current blocking or passage direction, and in that the control supervisor (CALC) is configured to be able to control the current blocking or passage means (8A, 8B, 9A,9B) to block or allow the passage of current in one direction or the other in said current blocking or passage means (8A, 8B, 9A, 9B) and in which the DC power supply connection (3) is linked to a first DC / AC converter (5) itself linked to a public electricity supply network (6), said system further comprising a second DC power connection linked to a second DC / AC converter (5B).

2. System (1) according to claim 1, wherein the second DC connection is connected on one hand to the second DC / AC converter (5B) and on the other hand to each battery energy storage unit or DC power source (2) via a second switching cell (7) for each battery energy storage unit (2).

3. System (1) according to claim 1, wherein the second DC connection is linked on the one hand to the second DC / AC converter (5B) and on the other hand to a single battery energy storage unit (2) via a switching cell (7).

4. System (1) according to any one of claims 1 to 3, wherein the second DC connection is coupled to the 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).

5. System (1) according to any one of claims 1 to 4, wherein at least one battery energy storage unit (2) is a vehicle battery.

6. System (1) according to any one of claims 1 to 5, wherein the means for blocking or passing current (8A,8B,9A,9B) comprise an active switch.

7. System (1) according to claim 6, wherein the active switch is of the MOSFET type.

8. System (1) according to any one of claims 1 to 5, wherein 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 mounted in series and back-to-back 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.

9. System (1) according to claim 8, wherein the switches (9A,9B) are of the IGBT type.

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