FR3135834A1 - Accumulator module integrating an elastic electrical connection - Google Patents

Abstract

Accumulator module integrating an elastic electrical connection Accumulator module (50) comprising: at least one row of accumulator cells (80) each having at at least one end an electrical connection tab (83; 84), a plurality spacers (100) inserted between the legs to be electrically connected together, elastic clamps (150) to tighten the legs against the spacers and establish an electrical connection between them. Figure for abstract: Fig. 11

Description

Accumulator module integrating an elastic electrical connection

The present invention relates to electrical energy storage devices comprising accumulator racks, and more particularly but not exclusively to containerized stationary storage devices.

The invention also relates to the modules used in the manufacture of such racks and storage devices.

The development of intermittent renewable energies such as photovoltaic or wind energy is accompanied by the need to benefit from stationary storage devices allowing energy to be stored during production periods and released outside of these.

Furthermore, the price of electricity today follows variations imposed by changes in demand, which can make it financially interesting to store energy during hours when the price is low, to release it when the price is higher.

Finally, there is a need to benefit from solutions to support the network in the event of high demand, for example to supply fast charging stations for motor vehicles.

To meet these needs, storage devices were proposed comprising maritime standard containers, in which racks of accumulator modules, a cold production system and a power conversion system are arranged.

The racks are most often made from modules identical to those developed for the automobile industry, and have frames on which the modules are introduced while being spaced from each other vertically, these modules generally being of approximately parallelepiped shape, of long side oriented horizontally.

Modules developed for the automotive industry are generally complex, because the mechanical structure used to hold the cells must resist the vibrations and accelerations encountered on a vehicle. The reinforcement of the mechanical structure of these modules comes at the expense of storage capacity.

It was proposed to arrange the modules inside the container in two series of racks providing a circulation corridor between them. Such a corridor takes up space in the container to the detriment of storage capacity, and can encourage a person to enter the container between the series of racks, in the event of an incident such as a fire, thus exposing this is at an increased risk in the event of excessive combustion.

There is an interest in increasing the storage capacity on board the container, facilitating its manufacturing and maintenance, and improving safety and reliability.

According to a first of its aspects, the invention relates to an electrical energy storage device comprising:

• A speaker,
• inside the enclosure, a plurality of racks arranged side by side in the enclosure and each comprising a plurality of accumulator modules, each rack comprising at least two accumulator modules stacked vertically and having a generally cross section rectangular, long side oriented vertically.

Such a device has the advantage of making it possible to have a large number of accumulator modules inside the enclosure, and thus to increase the storage capacity.

This configuration also lends itself well to cooling by circulation of liquid, particularly water, of the modules.

According to this first aspect, the device may have all or part of the following characteristics, considered separately or in combination:

• the device comprises two series of successive racks; these two series are arranged without a traffic corridor between them;
• each series of rack provides spaces at the front and rear of the enclosure receiving a refrigeration unit and a power conversion system (called “Power Conversion System”);
• each rack comprises a chassis having two uprights between which the modules are arranged; this chassis can be limited to these two amounts, which makes it possible to limit the number of parts to be assembled;
• each rack has between three and five, preferably four, modules stacked vertically; such a number allows good filling of the container;
• the enclosure is defined by a maritime standard container, in particular the 20-foot standard;
• each module comprises accumulator cells of flattened elongated shape, oriented vertically;
• the cells are arranged within each module in two rows arranged side by side;
• the cells of a row are held together by clamping, with the interposition of an interlayer, in particular a sheet of electrically insulating foam, between two consecutive cells.

According to a second of its aspects, independently or in combination with the above, the invention relates to an electrical energy storage device comprising:

• An enclosure made up of a maritime standard container, and inside the enclosure,
  • two series of racks arranged side by side in the enclosure and each comprising a plurality of accumulator modules, these series of racks being arranged within the container along it without preserving a central circulation aisle between them,
  • at least one power conversion system accessible through one end of the container,
  • at least one cold production system, accessible from the opposite end,

a water cooling system, coupled with the cold production system, to cool the modules.

Such a device has the advantage of allowing a large number of accumulator modules to be placed inside the enclosure, taking up the available space in an optimized manner, and thus increasing the storage capacity. In addition, in the absence of a central circulation corridor the risk of having a person present in the container in the event of an incident is eliminated. Finally, water cooling makes it possible to gain in compactness and efficiency.

According to a third of its aspects, independently or in combination with the above, the invention relates to an accumulator module comprising:

• At least two rows of accumulator cells, these cells each having a generally flattened parallelepiped shape with opposite main faces,
• at least one heat exchanger plate arranged between the two rows and in thermal contact with them, this plate being oriented substantially perpendicular to the main faces of the cells.

Such a plate and arrangement of cells makes it possible to obtain efficient cooling, particularly at the heart of the module, while having a compact and easy to assemble module.

According to this third aspect, the module may have all or part of the following characteristics, considered separately or in combination:

• two end cheeks between which the rows are arranged;
• each cheek rests against the plate, or even against a cell opposite the row; we can then use the plate to precisely adjust the gap between the cheeks and thus control the tightening exerted by the cheeks on the modules;
• the cheeks are held tight together by at least one tightening strap;
• metal ribbons are placed between the cheeks, on either side of the rows of cells, under the tightening straps, to serve as spacers and squaring and prevent the cheeks from pivoting against the plates; these ribbons are preferably the same length as the central plate and make it possible to guarantee the length in the compressed state of the stack of cells in the row;
• each cheek has at least one groove for receiving the strap;
• each cheek has fixing means on an upright of a support frame of the module, in particular pads for receiving fixing screws;
• the cheeks are crossed by holes in fluid communication with internal conduits of the exchanger plate;
• spacers are placed between the cells, preferably foam spacers; this allows you to benefit from the elasticity of the foam to compensate for expansion of the modules, while ensuring good mechanical support of the modules;
• the cells have connection tabs electrically connected together by elastic connections;
• each elastic connection comprises at least one spacer placed between two consecutive legs and an elastic clamp for tightening the legs on the spacer(s) placed between them;
• a thermal paste is placed between the exchanger plate and the rows of cells.

The invention also relates to an electrical energy storage device comprising:

• An enclosure made up of a maritime standard container, and inside the enclosure,
  • two series of racks arranged side by side in the enclosure and each comprising a plurality of accumulator modules according to this third aspect, these series of racks being arranged within the container along it without preserving a traffic aisle central between them,
  • at least one power conversion system accessible through one end of the container,
  • at least one cold production system, accessible from the opposite end,
  • a water cooling system, coupled with the cold production system, to cool the modules.

According to a fourth of its aspects, independently or in combination with the above, the invention relates to an accumulator module comprising:

• At least two rows of accumulator cells, these cells each having a generally flattened parallelepiped shape with opposite main faces,
• two end cheeks extending parallel to the main faces of the cells,
• at least one holding member configured to mechanically bias the end cheeks towards each other.

Such a module has the advantage of being easier to construct, since the cells can be held mechanically one after the other by the tightening induced by the end cheeks. Such a solution notably limits the use of screw fixings.

The cheeks can also be arranged to contribute to the cooling of the cells, being preferably traversed by the cooling liquid circulating in the aforementioned exchanger plate. The cheeks can still serve as a mechanical interface for mounting modules on racks, simplifying construction and maintenance.

According to a fifth of its aspects, independently or in combination with the above, the invention relates to an accumulator module:

• at least one row of accumulator cells each having an electrical connection tab at at least one end,
• a plurality of spacers inserted between the legs to be electrically connected together,
• elastic clamps to tighten the legs against the spacers and make an electrical connection between them.

Such an assembly has the advantage of limiting, or even avoiding, the use of screws to make electrical connections, which simplifies manufacturing. In addition, such an elastic connection avoids the creation of a connection by welding or brazing, which is particularly stiff and subject to fatigue cracking in the event of cycled stress, for example linked to thermal expansion. Finally, the connection can be easily dismantled, if necessary, and the installation of the clamps can be carried out by a robot.

According to this fifth aspect, the module may have all or part of the following characteristics, considered separately or in combination:

• the spacers are electrically conductive; the spacers can, depending on their location, connect two consecutive cell legs of the same polarity or of opposite polarities;
• the spacers are carried by the same support; we can thus have two identical supports per module, one at the top and one at the bottom, which simplifies connections between modules within the rack and between the rows of the same module; this support can be made of a plastic material, possibly reinforced;
• two rows of cells are arranged side by side, each of the spacers of one row occupying the same axial position as a corresponding spacer of the other row;
• the spacers are for a row of cells grouped for example by three, with the exception of the first and last spacers;
• each clamp has a general U shape, to clamp the legs and spacer(s) between the uprights of the clamp;
• the module comprises two rows of cells provided with connection tabs at their lower and upper ends, spacers for electrically connecting upper cell tabs, spacers for electrically connecting lower cell tabs, clamps for tightening the tabs on the spacers .

The invention also relates to a rack comprising a plurality of modules.

The invention also relates to an energy storage device, comprising a plurality of racks according to this fifth aspect, arranged in a container, in particular a maritime standard container.

According to the invention, the cells can use any type of technology, for example Lithium ion, Lithium polymer, Lithium iron phosphate, Lithium metal polymer or Lithium air, among other Lithium-based technologies; the cells can still use other battery technologies, other than Lithium-based.

The invention can be better understood on reading the detailed description which follows, of a non-limiting example of implementation of the invention, and on examining the appended drawing, in which:

• there represents schematically and partially, in perspective, a storage device according to the invention, the roof of the container having been removed,
• there is a side view of the device of the ,
• there represents in isolation, in perspective, an example of a rack according to the invention,
• there represents a detail of the ,
• there represents in isolation an amount of the rack chassis,
• there represents in isolation, in a partial and schematic manner, an example of a module according to the invention,
• there represents in isolation the end cheeks of the module of the ,
• there represents in isolation the two rows of cells of the module of the without the end cheeks,
• there represents in isolation the exchanger plate arranged between the rows of cells,
• there represents a detail of realization of an example of electrical connection between the cells of a row,
• there represents, in a partial and schematic manner, an example of an interconnection system, only one of the clamps being represented in isolation,
• there illustrates an example of physical connection between the modules of a rack,
• there is an electrical diagram of the connection between the modules of a rack,
• there represents in isolation, in a partial and schematic manner, an example of a cell, and
• there represents in isolation, in a partial and schematic manner, an example of interlayer insulation.

detailed description

Figures 1 and 2 show an example of a storage device 1 in accordance with the invention, comprising a maritime standard container 10, preferably a 20-foot standard, inside which two series 2a and 2b of racks are arranged. 20.

In the illustrated example, the container 10 has doors 11 on all its vertical sides, equipped with seals to guarantee the desired seal.

The container may be of standards other than the 20-foot standard, or even be of non-standard dimensions.

The container 10 may include a structural metal frame, with so-called “ISO” corners allowing the attachment of lifting or anchoring devices.

The series 2a and 2b of racks 20 each extend along the container, from a certain distance from its longitudinal ends 10a and 10b, making it possible to provide inside the container two spaces 12 and 13 which can respectively receive a cold production system 30 and a power conversion system 40 (also called “Power Conversion System”).

This power conversion system may include one or more inverters making it possible to transform the direct voltage at the terminals of the accumulators into an alternating voltage, intended for example to be injected into the network, via a step-up transformer if necessary.

The racks 20 do not extend over the entire height of the container, providing a space 14 above it allowing the passage of power cables, cooling ducts, cables of the management system (also called "Battery Management System") and various cables, for example connected to door opening detectors.

Each rack 20 occupies a little less than half of the available width inside the container, the two series 2a and 2b being slightly spaced apart from each other, so that they do not offer any circulation corridor for anyone. inside the container.

The container 10 may have openings 16 for cable passages and/or conduits, opening into spaces 12 and 13.

An example of a rack 20 is shown in Figures 3 to 5.

Each rack 20 has several modules 50, stacked vertically, and fixed to a chassis 60 comprising two opposite uprights 61, one of which is shown in isolation at the .

In the example considered, each rack 20 comprises four modules 50 superimposed vertically, giving the rack a generally flattened parallelepiped shape, with a long side oriented vertically.

The main faces 20a and 20b of the rack extend vertically, perpendicular to the long sides of the container 10.

Within each series 2a or 2b of racks 20, two successive racks are closely spaced.

The number of racks 20 per series 2a or 2b is for example between 15 and 25 for a 20-foot maritime standard container, for example equal to 20 as illustrated.

A module 50 has been shown in isolation on the .

This module 50 comprises two rows 50a and 50b of individual cells 80, visible more particularly on the , between which is arranged an exchanger plate 140, which has internal channels 141 which can be passed through by a cooling liquid.

Each cell 80 presents, as illustrated in the , a general flattened shape, elongated along a longitudinal axis which is oriented vertically.

The opposite main faces 81a and 81b are planar and parallel and electrically insulating spacers such as that shown in can be arranged between two consecutive cells 80. This interlayer is for example constituted by a sheet of cellular material 90.

The module 50 has two opposite end cheeks 120, between which the two rows 50a and 50b of cells 80 are clamped.

Each cheek 120 can present on its exterior face, as can be seen on the , two grooves 121, each receiving a tightening strap 130 (also called strapping).

These grooves 121 can be made, as illustrated, between parallel ribs 122.

Each cheek 120 can also include, for example in the four corners, studs 123 serving as housings for fixing screws of the module on the upright 61 of the chassis.

Drillings 124 pass through the cheek 120 for the fluid connection, through the cheek, to the internal channels 141 of the exchanger plate 140, as visible on the .

A thermal paste can be placed between the plate 140 and the cells 80, to improve the heat exchange.

Ribbons 132 are arranged are the strap 130 between the cheeks 120. These ribbons 132 are the same length as the exchanger plate 140, come to bear with their ends against the internal faces of the cheeks 120 and serve as a spacer and square to ensure the parallelism of the cheeks and guarantee the length of the rows of cells 80.

In the example considered, each cell 80 has electrical connection tabs 83 and 84 of respective positive and negative polarities, which are oriented parallel to the main faces 81a and 81b, and define the longitudinal ends of the cell.

The cells 80 are stacked within each row, alternating cells and spacers 90, along the row. The cells 80 can be oriented, within each row, with their positive connection tab at the top or at the bottom, depending on the way in which the cells are electrically connected to each other.

For example, as shown in , within a row, the cells 80 are arranged by alternating a pair of two cells oriented similarly, for example both with their positive electrical connection tab 83 at the top, and a pair of two cells oriented similarly but in a inverted configuration relative to the adjacent pair, for example with both their negative connection tab 84 at the bottom.

To electrically connect two legs 83 or 84 of two consecutive cells located on the same side of the module, an electrically conductive spacer 100 is placed between these legs, as illustrated in .

All of the spacers 100 present on the upper side of the module are carried by a support 110 which is arranged to attach to the module, for example by bearing on the exterior faces of the cheeks 120.

The electrical connection of modules 50 within a rack 20 is for example as illustrated in .

For example, we have a parallel assembly of cells in groups of four, and serialization of the groups thus constituted.

By arranging, as illustrated in , three spacers 100 between the four consecutive cell connection tabs, for example between the two tabs 84 of a first and a second cell consecutive to the first, between the tab 84 of the second and the tab 83 of the third consecutive cell, then between the tab 83 of the third and the tab 83 of the fourth consecutive cell, the desired electrical connection is made.

The tabs 83 and/or 84 are held tight against the spacers 100 by elastic clamps 150, U-shaped, the amounts 151 of which press on the tabs located outside the groups of tabs and spacers to be connected together.

These clamps 150 are made of a material with a high elastic limit and ensure, through their own deformation, the contact pressure necessary at the interface between the tabs and the spacers to obtain a reliable electrical connection resistant to fatigue cycles. .

The installation of the clamps 150 can be carried out robotically.

The use of pliers 150 allows easy dismantling of the electrical connection, to replace a faulty cell for example.

If necessary, additional electrical elements not shown, such as plates, can be added to facilitate the electrical connection.

In the example illustrated, each row of cells 80 has twelve clamps 150 which ensure the tightening of the spacers 100 on the cell tabs from the third to the antepenultimate.

We thus obtain at one end of the two rows two cells which are connected to each other using a spacer 100, and can be connected together or to another pair of cells by a bridging or a cable.

There schematically represents an example of possible wiring.

The + and – terminals of rack 20 are for example located at the front, on the lower legs of the front cells of the two rows of the lower module.

The racks 20 can be connected together in series and in parallel to obtain, for example, a direct voltage at the inverter input of approximately 1500 V, and the desired storage capacity.

Cell voltage and temperature monitoring can be carried out using a suitable monitoring system.

It may be advantageous to take advantage of the presence of the support 110 to attach to it various temperature and/or current sensors, as well as voltage measurement and/or cell balancing lines.

During operation of the device, the cells can be cooled by liquid by circulating the cooling liquid in the exchanger plates 140, through the end cheeks 120.

This coolant can be cooled by the refrigeration unit present at one end of the container. This refrigeration unit can communicate, if necessary, with one or more cooling towers external to the container.

In the event of a malfunction of one or more cells in a rack, it can be shut down by the monitoring system.

The device 1 which has just been described is easy to industrialize and highly reliable, thanks to the low number of screwed connections. In addition, the connection by spacers and clamps makes it possible to avoid and/or limit welding or brazing likely to cause fatigue cracking in the event of cycled stress, linked to thermal expansion for example.

Of course, the invention is not limited to the example which has just been described. In particular, we can have a different number of cells per module, and modules per rack.

The number of cells connected in parallel or series may be different.

Claims (9)

Accumulator module (50) comprising:

• at least one row of accumulator cells (80) each having at at least one end an electrical connection tab (83; 84),
• a plurality of spacers (100) inserted between the legs to be electrically connected together,
• elastic clamps (150) to tighten the tabs against the spacers and establish an electrical connection between them.

Module according to claim 1, the spacers (100) being electrically conductive. Module according to one of claims 1 and 2, the spacers (100) being carried by the same support (110). Module according to one of the preceding claims, comprising two rows (50a, 50b) of cells (80) arranged side by side, each of the spacers of one row occupying the same axial position as a corresponding spacer of the other row. Module according to any one of the preceding claims, the spacers being, for a row of cells, grouped by three, with the exception of the first and last spacers. Module according to any one of the preceding claims, each clamp (150) having a general U shape, to clamp the legs and spacer(s) between the uprights (151) of the clamp. Module according to any one of the preceding claims, comprising two rows (50a, 50b) of cells (80) provided with connection tabs at their lower and upper ends, spacers (100) for electrically connecting upper tabs of cells, spacers for electrically connecting lower legs of cells, clamps (150) for tightening the legs on the spacers. Rack (20) comprising a plurality of modules according to any one of the preceding claims. Energy storage device (1), comprising a plurality of racks according to claim 8, arranged in a container (10), in particular a maritime standard container.