WO2021052572A1

WO2021052572A1 - A modular energy storage system

Info

Publication number: WO2021052572A1
Application number: PCT/EP2019/074905
Authority: WO
Inventors: Sondre LANDVIK; Sebastien Ragot; Jonatan SVENSSON
Original assignee: Volvo Truck Corporation
Priority date: 2019-09-17
Filing date: 2019-09-17
Publication date: 2021-03-25

Abstract

A battery module (200) for a modular battery pack, the battery module (200) comprising a frame and one or more battery cells enclosed by the frame, wherein the frame has a height (H) smaller that a depth (D), and a width (W) of the frame, the depth (D) and width (W) of the frame defining a surface portion of the battery module, the width (W) and height (H) of the frame defining a first edge portion (303) of the battery module, the depth (D) and height (H) of the frame defining a second edge portion of the battery module, wherein the battery module (200) is arranged to be electrically connected in parallel to another battery module arranged adjacent to the battery module with an edge portion and/or a surface portion facing a corresponding surface or edge portion of the other battery module.

Description

A modular energy storage system

TECHNICAL FIELD

The present disclosure relates to energy storage systems (ESS) for electric vehicles and for hybrid electric vehicles. The invention can be applied in heavy-duty vehicles, such as trucks, buses and construction equipment. Although the invention will be described mainly with respect to heavy-duty vehicles, the invention is not restricted to this particular vehicle class but may also be used in other vehicles such as cars and marine vessels. The invention is furthermore applicable in stationary energy storage systems, such as systems for household use. BACKGROUND

Electric and hybrid-electric vehicles often require significant electrical energy storage capacity for propulsion. However, requirements in terms of capacity, power outtake, and form factor varies significantly between different types of vehicles and between different applications. It is difficult to design a single battery pack with a capacity and geometry that fulfils the packaging requirements and energy storage specifications of all types of vehicles. With the development of a battery pack and battery cell being a cost-driving factor in overall vehicle design and production, it is desired to reduce battery customization and vehicle-specific design work. US 2016/0093854 A1 discloses a lithium ion battery system comprising prismatic battery cells which can be fitted into cell casings of varying geometry. The battery cells are stackable, and the cell casings can therefore be of different height.

There is a need for a battery pack design which can be efficiently adapted to meet a wide range of requirements on form factor and battery capacity for different types of electric and hybrid-electric vehicles.

There is furthermore a need for a battery pack design which can efficiently be recycled and re-purposed for other uses once the battery pack no longer is able to meet vehicular requirements.

SUMMARY It is an object of the present disclosure to provide a modular energy storage system which can be efficiently adapted to meet requirements of different types of vehicles, and which can be re-purposed at least in part for alternative use once the battery pack has outlived its useful lifetime as a vehicle battery pack and is no longer able to meet vehicular requirements.

This object is obtained by a battery module for a modular battery pack. The battery module comprises a frame and one or more battery cells enclosed by the frame. The frame has a height H smaller that a depth D, and a width W of the frame. The depth D and width W of the frame defines a surface portion of the battery module. The width W and height H of the frame defines a first edge portion of the battery module, while the depth D and height H of the frame defines a second edge portion of the battery module. The battery module is arranged to be electrically connected in parallel to another battery module arranged adjacent to the battery module with any of an edge portion and a surface portion facing a corresponding edge or surface portion of the other battery module.

This way a large variety of different battery pack form factors and energy capacity requirements can be fulfilled based on a common building block, which is an advantage. The modular battery pack can efficiently be adapted to meet requirements of different types of vehicles and different transportation applications.

According to aspects, one or more bushings are arranged on a surface portion and/or an edge portion. The bushings provide mechanical isolation and protects the battery modules and the comprised battery cells from outside vibration and mechanical impact. The bushings simplify mounting the modular battery pack to, e.g., a vehicle frame, since the modular battery pack then comprises internal mechanical isolation, voiding or at least alleviating the need for mechanical isolation between vehicle frame and battery pack.

According to aspects, the frame comprises an integrated cooling channel for circulating a cooling medium to cool the one or more battery cells. This integrated cooling channel simplifies cooling system design and provides for efficient cooling of the battery modules.

According to aspects, the battery module comprises a bracket for attaching the battery module to an exterior casing of a modular battery pack. The bracket enables a structure with mechanical integrity, which is an advantage. The bracket also allows for an efficient assembly process when fitting the battery module to the exterior casing.

According to aspects, the battery module is arranged to be re-purposed as a part of a stationary battery pack system. This allows for re-use of battery modules which no longer meets requirements of the vehicular application, thereby extending lifetime and use of each re-purposed battery module. Individual battery modules may be replaced in a modular battery pack, thereby extending the total lifetime of the battery pack. The stationary battery pack system may, e.g., be a battery pack system for household use, orfor supplying energy to a local facility of some sort.

There is also disclosed herein a modular battery pack comprising one or more battery modules electrically connected in parallel, and a control unit arranged to control the one or more battery modules. The battery modules and the control unit are enclosed by an exterior casing. This way a versatile modular battery pack with integrated control function is provided. The geometry of the battery pack can be adapted to a specific use and/or to a specific type of vehicle. The exterior casing can then be filled by battery modules which are easily assembled by parallel electrical connection. The battery modules are then connected to the control unit, whereby a fully functioning battery pack with control functionality is obtained.

According to aspects, the control unit comprised in the modular battery pack is configured with an outtake power capacity in dependence of the number of battery modules comprised in the modular battery pack. This allows for dimensioning the control unit in dependence of the application, which allows for cost reduction in that some control units may be less advanced and/or associated with reduced specification on, e.g., outtake power and the like. Exterior casings with many battery modules can be fitted with a more capable control unit (at higher cost) compared to exterior casings fitted with a smaller number of battery modules.

According to aspects, the exterior casing comprises one or more brackets for mounting the battery pack to a vehicle frame. This allows for efficient vehicle assembly, which is an advantage. The battery modules in the casing interior may optionally already be mechanically isolated from each other, which means that the one or more brackets for mounting the battery pack to the vehicle frame require less or no isolation, which is an advantage.

According to aspects, the exterior casing is a rigid metal or plastic casing configured with a form factor in dependence of the geometrical arrangement of battery modules comprised in the modular battery pack. This means that the geometrical variation due to the different requirements of different vehicles are captured mainly by the exterior casing, which can be efficiently and cost-effectively molded or formed in various shapes. The exterior casing is then filled with the pre-determined number of battery modules and a control unit to make a complete modular battery pack. There are also disclosed herein control units, vehicles, marine vessels, stationary battery pack systems, computer program products, and electrical energy storage systems associated with the above-mentioned advantages.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled person realizes that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples. In the drawings:

Figures 1A-B illustrate example vehicles;

Figure 2 schematically shows modular battery packs; Figure 3 illustrates a battery pack module;

Figures 4A-C schematically show modular battery packs;

Figure 5 show example battery packs mounted to a vehicle frame;

Figure 6 schematically illustrates a control unit; and

Figure 7 shows an example computer program product.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain aspects of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments and aspects set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.

It is to be understood that the present invention is not limited to the embodiments described herein and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

Figures 1A and 1 B illustrate two example vehicles 100, 120. Both vehicles comprise electrical energy storage systems (ESS) for storing electrical energy. The first vehicle 100 is a smaller truck which can be used, e.g., for shorter distance transportation missions, perhaps as a delivery truck or the like. The truck 100 pauses often at loading docks and the like where the ESS can be at least partially re-charged. However, the available space for mounting the ESS may be limited to a relatively small vehicle frame portion 110.

The truck 120 is a larger truck compared to the truck 100 comprising larger sized frame portions 130, 140, 150 where battery packs may be mounted. The larger truck 120 can be used for, e.g., long-haul transportation missions where battery charging opportunities are scarcer. The energy requirement of the truck 120 is likely different from the smaller truck 100 (higher), and the available space for mounting an ESS is also different compared to the truck 100.

Due to the different requirements of the two example vehicles 100, 120, it is not optimal to use the same type of battery pack for both vehicles. Rather, some customization is warranted. However, customization and component variation drives cost and development time, and should preferably be minimized. With the development of a battery pack and battery cell being very expensive, it would be highly beneficial to find common building blocks that could be shared between different vehicles having different requirements on the ESS.

There is disclosed herein a battery module which comprises a frame unit with integrated cooling channels, and optionally also a number of bushings on the sides (for example 4 bushings). The frame unit is filled with battery cells and can be made compatible with both cylindrical and prismatic cell formats as well as battery pouch cell formats. The cells are connected in such a way that the module reaches a desired voltage level of the system of the final product. It shall therefore not be needed to serial connect battery modules together, but rather only parallel connect battery modules to keep the same voltage while increasing total stored energy. After combining a number of battery modules together to the desired energy level, these will then be joined by an electronic box or control unit before being encapsulated into an exterior casing which forms the exterior of the battery pack and protects the battery modules from mechanical impacts, vibration, and the like. The battery pack is then a fully functional battery pack with control functions and electronic interfaces.

A key concept behind the proposed ESS is that the battery modules can be arranged in many different ways and numbers, and when combined with the electronic box, the only non-shared component is the exterior casing. Thus, variation is mainly captured by different sizes of exterior casings, which are then fitted with variable numbers of battery modules in different geometries.

To cover a very wide range of energy levels, it is possible to construct different electronic boxes to so that the electronics are dimensioned to cope with the different currents involved.

The disclosed battery module is intended to be the common building block, which by itself does not act as a full battery pack. This allows a battery designer to combine as many of the modules needed to fulfil a given vehicle specification, which is an advantage in that it provides a large degree of design freedom without adding cost to the overall ESS design.

Depending on the configuration, the battery packs can be installed on the vehicle frame or chassis, under the vehicle cab, on the roof of, e.g., a bus, in the hull of a marine vessel, or in stationary systems, just to give a few examples.

Figure 2 illustrates a number of example modular battery pack geometries 210, 220, 230, 240, 250. Each geometry comprises one or more instances of the same battery modules 200. The battery modules are arranged adjacent to each other such that various stacks and other shapes are formed. The battery modules are prepared with interfaces to interface edge against edge as in the examples 240 and 250 or surface against surface as in the examples 220, 230.

With reference also to Figure 3, each battery module 200 comprises a frame 301 and one or more battery cells enclosed by the frame 301. The frame has a height H smaller that a depth D, and a width W of the frame 301. The depth D and width W of the frame 301 defines a surface portion 302 of the battery module. The width W and height H of the frame 301 defines a first edge portion 303 of the battery module, while the depth D and height H of the frame 301 defines a second edge portion 304 of the battery module. As discussed above, the battery module 200 is arranged to be electrically connected in parallel to another battery module arranged adjacent to the battery module with any of an edge portion 303, 304 and a surface portion 302 facing a corresponding edge or surface portion of the other battery module.

Thus, the battery modules can be arranged with edge-portion against edge-portion, and/or with surface portion against surface portion, as exemplified in Figure 2. This means that a large variety of different geometries are possible. The battery designer does not need to account for reaching a desired voltage level since the battery modules are configured to be connected in parallel, thereby maintaining a pre-determined voltage level regardless of battery pack geometry.

There is no limitation on a specific battery cell type or shape which can be used in the battery module 200, i.e., any of cylindrical battery cells, pouch battery cells, or prismatic battery cells, or some other type of battery cell may be used. Different types of battery cells can be combined in a single module.

The dimensions of the battery module may vary, and the present disclosure is not limited to any particular size of battery module. However, for heavy-duty vehicles, a height H between 50-200 mm, a depth D between 100-1000 mm, and a width W between 100-1000 mm may be suitable. According to a specific example, the battery module 200 has the dimensions 600x600x150 mm.

According to one example, again with reference to Figure 3, the frame 301 has a cuboid shape, and the surface portion 302 of the cuboid shape is a planar rectangular or square surface portion. This particular battery module shape is particularly suitable for stacking in different ways to obtain different battery pack geometries with mechanical integrity and robustness. The planar battery module shape allows for sandwiching modules inside the exterior casing, which increases structural integrity.

The battery module 200 optionally also comprises dampening and isolation devices that will allow for extra flexibility in how the different complete battery packs are mounted in the finished products. Some applications do not allow the battery pack to be too stiffly installed to the, e.g. vehicle, which means isolation devices are needed. Instead of isolating the whole battery pack, which adds complexity on a vehicle level and in production, it is proposed herein to add the isolating devices inside the battery pack allowing for a simpler attachment to the vehicle. The bushings may be rubber bushings or similar resilient isolation devices to allow each battery module 200 to be isolated from vehicle motion and vibration, instead of adding that complexity on a vehicle level. Thus, optionally, one or more bushings 310, 320, 330, 340 are arranged on a surface portion 302 and/or an edge portion 303, 304. The bushings are shown in Figure 3. It is, however, appreciated that various types of bushings or resilient members can be used. For instance, separate bushings 310, 320, 330 and/or vibration isolating tapes or strips 340 may be used. The dampening and isolation devices may also comprise spring-loaded suspension members or other types of mechanical dampeners.

According to some aspects, the frame 301 comprises an integrated cooling channel for circulating a cooling medium to cool the one or more battery cells. The battery module then comprises an interface for connecting with the cooling channel or channels of an adjacent battery module in the modular battery pack. The modular battery pack then preferably comprises a common interface for connecting the cooling channels to a cooling medium source on the vehicle. Some example cooling channels 430 are schematically illustrated in Figure 4.

With reference to Figure 4, each battery module 200 is configured to be enclosed by an exterior casing 401 which protects the battery module 200 from, e.g., mechanical impacts and the like. The exterior casing 401 also holds the battery modules in place relative to each other. Optionally, the battery module 200 comprises one or more brackets for attaching the battery module 200 to the exterior casing 401 of a modular battery pack 400. The battery modules 200 may also comprise mechanisms for attaching a battery module 200 to another battery module 200. Such mechanisms may, e.g., comprise snap-lock mechanisms, interference fit mechanisms, brackets, holes for attachment bolts and the like.

If one or more battery modules were to fail over time, it is possible to exchange only the failed battery module and balance it with the rest of the functioning battery modules in the battery pack. This way battery packs can be serviced by replacing individual battery modules instead of replacing the entire battery pack, which is an advantage.

With reference to Figure 4, there is disclosed herein a modular battery pack 400 comprising one or more battery modules 200 as discussed above, electrically connected in parallel, and a control unit 410, 420 arranged to control the one or more battery modules 200. The battery modules 200 and the control unit 410, 420 are enclosed by an exterior casing 401.

Preferably but optionally, the exterior casing 401 is a rigid metal casing configured with a form factor in dependence of the geometrical arrangement of battery modules 200 comprised in the modular battery pack 400. The control unit 410, 420 is optionally configured with an outtake power capacity in dependence of the number of battery modules 200 comprised in the modular battery pack 400. Thus, the control unit 410 may be configured to provide a larger outtake capacity compared to the control unit 420. The control unit is configurable to support a varying number of battery modules 200. The control unit may also comprise external interfaces or connecting to the integrated cooling channels of the battery modules 200. Some details of the control unit will be given below in connection to Figures 6 and 7.

With reference to Figure 5, the exterior casing 401 optionally comprises one or more brackets for mounting the battery pack to a vehicle frame 510. It is noted that the modular battery pack can be mounted in several different places, where the freedom of assembly is at least in part due to the different exterior casing geometries obtainable.

When a modular battery pack has served out its life in a vehicular application, it is possible to re-purpose the battery modules as a part of a stationary battery pack system. Thus, battery modules from one or more battery packs can be assembled into a larger stationary system. Consequently, there are disclosed herein both vehicles 100, 120 comprising the modular battery pack 400 and stationary battery pack system comprising the modular battery pack 400. The stationary battery pack may be a battery pack for household use or the like with less severe requirements on ESS performance compared to a vehicular system.

Figure 6 schematically illustrates, in terms of a number of functional units, the components of a control unit 410, 420 according to embodiments of the discussions herein. This control unit is arranged to be enclosed by the exterior casing 401 as shown in, e.g., Figures 4 A-C. Processing circuitry 610 is provided using any combination of one or more of a suitable central processing unit CPU, multiprocessor, microcontroller, digital signal processor DSP, etc., capable of executing software instructions stored in a computer program product, e.g. in the form of a storage medium 630. The processing circuitry 610 may further be provided as at least one application specific integrated circuit ASIC, orfield programmable gate array FPGA.

Particularly, the processing circuitry 610 is configured to cause the control unit 410, 420 to perform a set of operations, or steps, for controlling a modular battery pack 400. For example, the storage medium 630 may store the set of operations, and the processing circuitry 610 may be configured to retrieve the set of operations from the storage medium 630 to cause the control unit 410, 420 to perform the set of operations. The set of operations may be provided as a set of executable instructions. For instance, the processing circuitry 610 may be configured in dependence of the number of attached battery modules 200 and perform operations accordingly.

The storage medium 630 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

The control unit 410, 420 may further comprise an interface 620 for communications with at least one external device. As such the interface 620 may comprise one or more transmitters and receivers, comprising analogue and digital components and a suitable number of ports for wireline or wireless communication.

The processing circuitry 610 controls the general operation of the control unit 410, 420, e.g., by sending data and control signals to the interface 620 and the storage medium 630, by receiving data and reports from the interface 620, and by retrieving data and instructions from the storage medium 630. Other components, as well as the related functionality, of the control node are omitted in order not to obscure the concepts presented herein.

Figure 7 illustrates a computer readable medium 710 carrying a computer program comprising program code means 720 for performing operation in the control unit 410, 420, when said program product is run on a computer. The computer readable medium and the code means may together form a computer program product 700.

Claims

1. A battery module (200) for a modular battery pack (400), the battery module (200) comprising a frame (301) and one or more battery cells enclosed by the frame (301), wherein the frame has a height (H) smaller than a depth (D), and a width (W) of the frame (301 ), the depth (D) and width (W) of the frame (301 ) defining a surface portion (302) of the battery module, the width (W) and height (H) of the frame (301 ) defining a first edge portion (303) of the battery module, the depth (D) and height (H) of the frame (301) defining a second edge portion (304) of the battery module, wherein the battery module (200) is arranged to be electrically connected in parallel to another battery module arranged adjacent to the battery module with any of an edge portion (303, 304) and a surface portion (302) facing a corresponding edge (303, 304) or surface (302) portion of the other battery module.

2. The battery module (200) according to claim 1 , wherein the frame (301 ) has a cuboid shape, and where the surface portion (302) of the cuboid shape is a planar rectangular or square surface portion.

3. The battery module (200) according to claim 1 or 2, where the height (H) is between 50-200 mm, the depth (D) is between 100-1000 mm, and the width (W) is between 100- 1000 mm.

4. The battery module (200) according to any previous claim, where one or more bushings (310, 320, 330, 340) are arranged on a surface portion (302) and/or an edge portion (303, 304).

5. The battery module (200) according to any previous claim, where the frame (301) comprises an integrated cooling channel (430) for circulating a cooling medium to cool the one or more battery cells.

6. The battery module (200) according to any previous claim, where the one or more battery cells comprise any of; cylindrical battery cells, prismatic battery cells and/or pouch cells.

7. The battery module (200) according to any previous claim, comprising a bracket for attaching the battery module to an exterior casing (401) of a modular battery pack (400).

8. The battery module (200) according to any previous claim, arranged to be re purposed as a part of a stationary battery pack system.

9. A modular battery pack (400) comprising one or more battery modules (200) according to any of claims 1-9 electrically connected in parallel, and a control unit (410, 420) arranged to control the one or more battery modules (200), wherein the battery modules (200) and the control unit (410, 420) are enclosed by an exterior casing (401).

10. The modular battery pack (400) according to claim 9, wherein the control unit (410, 420) is configured with an outtake power capacity in dependence of the number of battery modules (200) comprised in the modular battery pack (400).

11. The modular battery pack (400) according to claim 9 or 10, wherein the exterior casing (401) comprises one or more brackets for mounting the battery pack to a vehicle frame (510).

12. The modular battery pack (400) according to any of claims 9-11 , wherein the exterior casing (401) is a rigid metal or plastic casing configured with a form factor in dependence of the geometrical arrangement of battery modules (200) comprised in the modular battery pack (400).

13. A vehicle (100, 120) comprising a modular battery pack (400) according to any of claims 9-12.

14. A marine vessel comprising a modular battery pack (400) according to any of claims 9-12.

15. A stationary battery pack system comprising a modular battery pack (400) according to any of claims 9-12.