WO2011000826A1

WO2011000826A1 - Method for cooling battery packs and battery pack divided into modules

Info

Publication number: WO2011000826A1
Application number: PCT/EP2010/059201
Authority: WO
Inventors: Norbert Huber; Kerstin HÄSE; Wolfgang Weydanz; Karl-Josef Kuhn
Original assignee: Siemens Aktiengesellschaft
Priority date: 2009-06-30
Filing date: 2010-06-29
Publication date: 2011-01-06
Also published as: DE102010025525A1

Abstract

The invention relates to a method for cooling battery packs (1), wherein at least one battery pack (10) is divided into a plurality of modules (11) and each module (11) is cooled separately. The invention further relates to a battery pack (10), which is divided into modules (11), and wherein each module comprises at least one cooling device (30, 31, 32, 33).

Description

description

Method of cooling battery packs and battery pack divided into modules

The invention relates to a method for cooling battery packs, wherein at least one battery pack is divided into a plurality of modules, and a battery pack, which is subdivided into modules.

Batteries are used in the art in many fields. The aim is a power-independent operation of electrical equipment, such. Bulbs, machinery or vehicles. Vehicles require high current densities to drive electric motors over long periods of time. This places high demands on the batteries used and can lead to rapid aging. The battery of an electric vehicle is the crucial one

Component for the range of the vehicle. The battery capacity is limited by the factors battery price, battery weight and available space. A single battery block, also referred to below as a module, ideally uses a contiguous space which is only available for vehicles specially designed for this purpose. A module is made up of a large number of individual battery cells, hereinafter referred to as cells. Another problem is that with a large, generally cooled module, which may comprise 50 or up to several thousand cells, the temperature variation of the cells with each other can be very large. However, the required deviation of modules in vehicles is max. 5 K. Equipping each cell with a temperature sensor in order to be able to control or regulate optimal cooling is very expensive. Modern modules are constructed, for example, from lithium-ion batteries. In the prior art, each larger lithium-ion battery must be equipped with a temperature monitor. On the one hand, it should ensure that no extreme temperatures are reached during operation. This primarily ensures safe, but also life-time optimized operation. On the other hand, it should be ensured by an approximation of the cell temperatures that the cells are all operated similarly in terms of temperature. This avoids a different aging, which leads to a deterioration of the performance of the battery. Ideally, the cell temperatures are kept essentially the same, with a temperature deviation between cells of 2 to 5 K. In order to avoid shutdown of the entire battery at too high a temperature, cooling must continue to be provided. This, if properly designed, also helps balance the temperature across the battery pack. The typical cooling arrangement in the prior art provides a single cooling circuit, which takes into account the temperature of a single cell in the case of a temperature control.

For example, e.g. in the small series Tesla Roadster a coherent battery pack consisting of 6831 pieces of 18650 lithium-ion "high energy" cells, which have a diameter of 18mm and a length of 65mm, housed in a steel container. The cells are actively cooled with a water-glycol mixture. The vehicle is a two-seater and was designed in such a way that the construction package is available for the battery pack. Battery pack and vehicle design must be consistently coordinated with each other in this solution. The Tesla costs about 10 000 € and thus offers no cheap solution for the mass market. The test vehicle Mini E Cooper from BMW was for the

Battery pack, the rear bench removed to install enough battery capacity. The cooling takes place via an air blower. There are 5088 medium power 18650 cells in one Total battery installed. Due to this installation solution, the space available in the vehicle interior is severely limited.

In the test vehicle, Ruf Greenster, the battery, consisting of 180 cells in 18 modules, is divided into several subunits of different sizes; these are currently not cooled.

In the GM Volt, a plug-in hybrid, the battery pack is designed to be very long, so that it fits in the cardan tunnel.

The trend in electric vehicles today clearly goes to cells with larger capacity. This requires a smaller number of cells in the battery. It is planned to operate the electric vehicles to be built in a larger series with lithium-ion cells of about 10-60Ah size. This reduces the number of cells per vehicle to an order of 100-500 cells.

The modules will thus consist of 8-12 cells in series, with corresponding voltages below 60V, and one or a few cells connected in parallel. The Mitsubishi "i MiEV", the first series electric vehicle with lithium-ion cells, uses eg LEV50 cells from GS Yuasa with 50 Ah capacity. Each 4 cells are connected in series to form a module. Out of 24 of these modules, all connected in series, the battery pack is built with 330V voltage. In the above-described trend toward cells with high power density, problems of heat development of the cells in operation, ie both charging and discharging, increase and active cooling becomes imperative. With increasing heat development, which can occur differently in cells of the modules, spatially and temporally, problems such as different aging of the cells are intensified by different thermal conditions. The object of the present invention is therefore to provide a method for improved cooling of battery packs, which counteracts a rapid aging of battery packs and thus leads to better durability and cost savings. The possibility of a better spatial distribution of modules of the battery pack is to be created and savings in cooling by reducing the cost of equipment are made possible. Furthermore, the invention comprises a battery pack, which is divided into modules, and an improved cooling, with the aforementioned advantages allowed.

The stated object is achieved with respect to the method for cooling battery packs with the features of claim 1 and with respect to the battery pack with the features of claim 8.

Advantageous embodiments of the method for cooling battery packs and with respect to the battery pack will be apparent from the respective associated dependent claims. The features of the main claims may be combined with each other and with features of the subclaims and features of the subclaims. The inventive method for cooling battery packs comprises the division of at least one battery pack into a plurality of modules, each module being cooled independently.

This allows a division of the battery pack and an arrangement in different places. Even with different stresses and / or temperatures of the individual modules, a cooling system corresponding to the module can be carried out by the independent cooling of each module. This prevents a different aging of the modules and the battery pack receives its overall performance over a prolonged period of time. The cooling of each module can be controlled or controlled depending on the temperature of the respective module. As a result, a module-specific temperature control or cooling is possible. A sensor may measure the temperature at each module and a controller or controller, in particular an electronic controller or controller, may adjust the temperature according to the measured temperature for the particular module by controlling or controlling a refrigerator. So all modules can be kept at the same temperature.

The cooling of a module can take place independently of the temperature and / or the cooling of other modules of the at least one battery pack. For each of a module, a cooling device, such. a cooling circuit or a fan may be provided. This is regulated or controlled as a function of the temperature of the respective module and independently of the temperature of other modules, in particular depending on the location of the respective module and its ambient temperature. The cooling of a module can also be done depending on the temperature of the module, which has the highest temperature value. This allows a simplified construction, with e.g. only one cooling circuit, the cooling fluid of which is set at a temperature necessary to cool the warmest module. Air or liquids such as oils, water or liquid carbon dioxide can serve as cooling fluids. As an alternative to the cooling circuit, it is also possible to control or regulate a central fan in accordance with the temperature of the warmest module.

The cooling of the at least one battery pack can be done in a vehicle. Then, the cooling of at least one module or all modules can be carried out depending on the respective position in the vehicle and / or the ambient temperature of the respective module in the vehicle.

A cooling of the modules of the at least one battery pack can be done so that over the entire battery pack uniform or nearly uniform temperature exists or arises. This allows the same or similar aging of all modules of the battery pack and improves the overall performance of the battery pack, in particular its long-term performance.

The battery pack according to the invention is divided into modules and each module has in each case at least one cooling device. The modular cooling concept allows the total battery to be divided into many individual sub-modules, with each module or a group of modules being equipped with autonomous cooling.

The battery pack or the battery pack is subdivided into many submodules, with preferably 8-12 cells, which are each equipped individually or in smaller subunits with autonomous cooling, which are regulated or controlled as a function of the locally present temperature or power load of the module can. Since the temperature deviation in a small module is significantly smaller than in a large one, there are overall smaller deviations between the modules in the temperature.

The subdivision of the battery pack into modules enables a distribution of the modules in the room. The assignment of at least one cooling device per module allows individually controlled or regulated cooling of each module. This can be done both depending on the location or a possible design of the environment and ambient temperature, as well as specific performance requirements of each module.

To make this possible, each module may have a temperature control device and / or temperature control device. Alternatively, all cooling devices can also be controlled or controlled individually by a central regulating or control device. The at least one cooling device of a module can each be independent of a cooling device of another module and / or of the cooling devices of all other modules. Thus, on each module, a sensor can measure the temperature and a control or regulation of each cooling device can be done individually depending on the respective measured temperature.

Alternatively, a cooling circuit can include the cooling devices, in particular all the cooling devices of the modules. This means that all cooling devices are connected and result in a cooling circuit. It can be provided valves, in particular control valves, for controlling or regulating a respective cooling device. Thus, e.g. divided by the control valves a central cooling fluid flow individually matched to the temperature of each module and adjusted by a valve, a partial fluid flow, which cools the respective module. Each module can be made up of cells. Cells are e.g. single lithium-ion batteries.

At least one fan, in particular per module, may be provided as an alternative to a cooling circuit, which is designed to supply the cells of the module with cooling air.

The battery pack may be arranged in a vehicle. Then, the modular design of the battery pack can allow a division of the battery pack to different modules or spatial areas of the vehicle. In the places different temperatures can prevail. For example, a different temperature may be present in the passenger compartment than close to a drive unit such as an electric motor. The individual cooling by individual cooling devices then allows to cool according to the ambient temperature of a module, for example, the same for all modules of a battery pack Temperature to be able to adjust. This prevents rapid aging of the battery pack.

The advantages associated with the battery pack are analogous to the advantages previously described with respect to the method for cooling battery packs and vice versa.

Preferred embodiments of the invention with advantageous developments according to the features of the dependent claims are explained in more detail with reference to the figures, but without being limited thereto.

The figures show: FIG. 1 a schematic representation of a battery pack

10 according to the prior art, with cooling device 30, 31, 32, 33 without dividing into modules, and

2 shows a schematic representation of a battery pack 10 according to the invention, subdivided into modules 11, each having a temperature sensor 41 for regulating 40 a cooling device 30, 31, 32, 33, and

Fig. 3 shows a battery pack 10, as shown in Fig. 2, but with control valves 42 to other modules

11 independent cooling of each module 11, and

Fig. 4 shows a battery pack 10, as shown in Fig. 2, but with completely separate, independent cooling devices 31, 30, 32, 33 per module 11, and

5 shows a module 11, which is cooled by a fan 33 independently of other modules.

In Fig. 1, a battery pack 10 is shown with cooling device 30, 31, 32, 33 according to the prior art. The battery Pack 10 includes n battery cells 20, where n is a natural number. For example, a battery pack in a motor vehicle may consist of around 20,000 cells. These can then be accommodated in a kind of battery pack at a location in the vehicle, for example in the trunk.

In order to avoid a shutdown of the entire battery at too high a temperature, cooling must continue to be provided. This also, if properly designed, assists in balancing the temperature across the battery pack 10. The typical prior art cooling arrangement provides a single cooling circuit 30 which, in the case of temperature control, accounts for the temperature of a single cell. The cooling device or cooling arrangement comprises a coolant connection 31 to the battery pack 10, which may be e.g. can be realized by a heat exchanger or a cooling plate. A cooling circuit 30 connects the coolant connection 31 to an active or passive recooling unit 32. This may be e.g. comprise a heat exchanger or a cooling plate, which can give off heat to the ambient air. A coolant circulation 33 can be realized in the form of a pump or a blower in the cooling circuit 30, and ensures transport of the coolant in the cooling circuit 30 from the coolant connection 31 to the cooling unit 32 and back again. When

Coolant or cooling fluid may be air, oils, water or other fluid, as well as gases having a high thermal coefficient, e.g. liquid carbon dioxide or air.

Fig. 2 shows a battery pack 10 according to the invention, in which the battery cells 20 are located at different locations, e.g. in a vehicle, distributed in modules 11 are distributed. Each module 11 has its own coolant connection 31 and its own temperature sensor 41. The single ones

Coolant connections 31 of the modules 11 are connected to each other via a common cooling circuit 30, in particular thermally via a cooling fluid, which in the cooling circuit 30 flows. Via the coolant connection 31, the cooling fluid absorbs heat quantity of the modules 11 and thus leads to a cooling of the modules 11. The cooling fluid flows through the cooling circuit

30 to at least one recooling unit 32. At the recooling unit 32, the coolant again partially or completely releases the absorbed heat to the environment, e.g. to the ambient air. A coolant circulation 33, e.g. a pump or a fan, keeps the cooling fluid or coolant in the cooling circuit 30 in motion, so that the cooling fluid can flow from the re-cooling unit 32 again to the coolant connections 31 of the modules 11.

The temperature of the modules 11 or the flow rate of the cooling fluid and / or the amount of heat removed at the recooling unit 32 can be regulated by a temperature controller 40. The control may depend on the temperature sensor 41 having the highest measured temperature value. This ensures that the cooling fluid can absorb enough heat to cool or keep all modules 11 below a critical temperature value. Among other things, the temperature controller 40 can regulate the flow rate and thus the cooling capacity of the refrigeration cycle 30 by controlling the performance of the refrigerant circulation (e.g., pump, blower) in accordance with the temperatures measured by the temperature sensors 41. Alternatively or additionally, the amount of heat released at the recooling unit 32 can also be regulated by the temperature controller 40.

In Fig. 3, an alternative embodiment of the cooling circuit 30 is shown according to the invention. The coolant connections

31 of the modules 11 are not fluidly connected in series as in FIG. 2 in the cooling circuit 30, but are fluidly connected to one another in parallel in the cooling circuit 30. The modules 11 can again be distributed at different locations in a vehicle and supplied with cooling fluid by a branched cooling circuit 30. A regulation of the coolant flows in each case to a module 11 takes place, for example, via a control valve 42 respectively assigned to the module 11. Each module 11 has at least one a temperature sensor 41, which measures the individual temperature of the module 11, for example, about the temperature of a cell 20 or averaged by cells 20. A temperature controller 40 controls the control valve 42 for the coolant connection 31 of the respective associated module 11 depending on the measured temperature. The proportion of cooling liquid of the cooling circuit 30 is thereby regulated or determined, which is fed to the coolant connection 31 of the associated module 11 and thus to the dissipated Amount of heat on the module 11.

Alternatively, instead of temperature controllers 40, which are each associated with a module 11, a central controller may be provided, for example, with a computer which controls the respective control valves 42 depending on the temperatures measured on the modules 11 with the temperature sensors 41, respectively. By the construction described above, the mechanical complexity of the cooling can be reduced and the uniformity of the cell temperatures can be increased. FIG. 4 shows a battery pack 10 according to the invention, in which each module comprises a separate cooling device separate from the other cooling circuits 30. The battery pack 10 is divided into modules 11 as in the previously described embodiments of the invention and the modules 11 are each distributed at different locations, for example in a vehicle. Each module 11 has its own, separate from the other cooling circuit 30, and is supplied via this with cooling fluid. The cooling circuit in turn has in each case a recooling unit 32 and a coolant circulation 33, which are fluidically connected via the cooling circuit 30 to the coolant connection 31 of a module 11. This not only a spatial distribution of the modules 11, but also the associated coolant circuits 30 or complete cooling devices is possible. Each cooling circuit 30 is regulated by a temperature sensor 41 assigned to the respective module 11 and the associated temperature regulator 40. Alternatively, a central rule be provided for all modules 11 eg in the form of a computer.

As an alternative to a fluid circuit 30, a fan or fan 33 can also serve for cooling, which is fastened directly to the module 11 and cools the latter, depending on the temperature measured at the module by the respective temperature sensor 41 and regulated by the respective controller 40. This is exemplified in Fig. 5. Cooling with air is particularly favorable in this case, because each unit or each module 11 equipped with a fan allows a simple construction. In the exemplary embodiment shown in FIG. 5, a module 11, comprising 3 cells 20, is supplied with fresh air via a fan as coolant circulation 33. The fresh air serves as a coolant. The individual control reduces the mechanical complexity of the cooling to a minimum and increases the uniformity of the cell temperatures. The exemplary embodiments described above indicate, by way of example only, individual possibilities of constructing the battery pack 10 according to the invention and carrying out the method according to the invention. Combinations of the exemplary embodiments described above, in particular in the figures, are also possible.

The division of the battery pack 10 in modules 11 with its own cooling allows flexible adaptation of the battery pack 10 to the respective space situation and a distribution in suitable spaces. In this case, the autonomous cooling together with the local temperature control per module 11 is important in order to guarantee a uniform lifetime of all cells 20 and modules 11 within eg a vehicle, in particular a motor vehicle such as automobile. A uniform service life can only be achieved via an almost constant temperature of all modules 11. At the same time, the cooling capacity for various battery modules 11 within, for example, a vehicle can depend on the installation location and the respective environment. Setting temperature can be set differently. Thus, despite different ambient temperatures (eg location in the vehicle or heating by ambient conditions), a more uniform lifetime of all cells can be achieved and possibly save energy.

In addition, the representation of the battery or the battery pack 10 in individual blocks or modules 11 an optimized weight distribution on the axles / wheels, for example. Easier to reach in a vehicle.

Further advantages of the invention for e.g. a vehicle are:

- The once designed battery modules 11 can be used for various vehicles

- The packaging in the vehicle can be cheaper

- In case of an impact or a "thermal runaway" only small units would be affected, the safety increases

- The drive power of the cooling decreases, since spatially and temporally limited the cooling can be activated

- Lower development costs of the battery

- It is a "plug and play" solution with the single modules conceivable, since these are all self-sufficient units. Ideally, it is only necessary to connect the main current path through all modules and a control line to the master BMS.

Claims

claims

1. A method for cooling battery packs (10), wherein at least one battery pack (10) is divided into a plurality of modules (11), characterized in that each module (11) is cooled independently.

2. The method according to claim 1, characterized in that the cooling of each module (11) is controlled or controlled depending on the temperature of the respective module (11).

3. The method according to any one of the preceding claims, characterized in that the cooling of a module (11) regardless of the temperature and / or cooling of other modules (11) of the at least one battery pack (10).

4. The method according to claim 1 or 2, characterized in that the cooling of a module (11) depends on the temperature of the module (11), which has the highest temperature value.

5. The method according to any one of the preceding claims, characterized in that the cooling of the at least one battery pack (10) takes place in a vehicle.

6. The method according to claim 5, characterized in that the cooling of at least one module (11) or all modules

(11) depending on the respective situation in the vehicle

and / or the ambient temperature of the respective module (11).

7. The method according to any one of the preceding claims, characterized in that cooling of the modules (11) of the at least one battery pack (10) takes place so that over the entire battery pack (10) is a uniform or nearly uniform temperature or arises.

8. battery pack (10) which is divided into modules (11), characterized in that each module (11) each having at least one cooling device (30, 31, 32, 33).

9. battery pack (10) according to claim 8, characterized in that each module (11) has a temperature control device (40) and / or temperature control means (40).

10. battery pack (10) according to claim 8 or 9, characterized in that the at least one cooling device of a module (11) each independently of a cooling device of another module (11) and / or of the cooling devices of all other modules (11) is.

11. Battery pack (10) according to claim 8 or 9, characterized in that a cooling circuit (30) comprises the cooling means, in particular all the cooling means of the modules (11), and valves (42) are provided, in particular control valves (42), for control or regulation of a respective cooling device.

12. battery pack (10) according to any one of claims 8 to 10, characterized in that a module (11) each of cells

(20) is constructed.

13. Battery pack (10) according to claim 12, characterized in that at least one fan (33) in particular per module

(11) is provided, which is designed to supply the cells (20) of the module (11) with cooling air.

14. Battery pack (10) according to any one of claims 8 to 13, characterized in that the battery pack (10) is arranged in a vehicle.