DE102009035480A1 - Battery i.e. lithium ion battery, for use in electrical powertrain of electric vehicle to store electricity, has valve units connected with battery modules such that cooling of modules is influenced depending on aging condition - Google Patents

Abstract

The battery has two battery modules (1, 2) electrically connected in parallel. A cooling device is provided for active cooling of the battery modules. Valve units (6, 7) are connected with the battery modules such that cooling of the battery modules is influenced depending on aging condition. The valve units are controlled depending on internal resistance of the respective battery module. The valve units include a controllable bypass line around one of the battery modules, where the bypass line is formed around a cooling heat exchanger (5). An independent claim is also included for a method for operating a battery for storing electricity.

Description

The The invention relates to a battery for storing electrical Energy according to which defined in more detail in the preamble of claim 1 Art. In addition, the invention relates to a method for Operating a battery for storing electrical energy with the features in the preamble of claim 9.

In electric drive trains, and in particular at pure electric vehicles, the range of the vehicle is essentially dependent on the stored electrical energy. Also at Hybrid vehicles this applies in so far as the range without Connection of the internal combustion engine and thus the range, without to generate emissions locally, from the amount of stored electrical Energy depends. With the goal, one as possible to realize high range, ie the amount of stored to increase electrical energy, one is in general endeavors to have all available installation spaces equipped with electrical energy storage in the form of batteries. In order to make the best possible use of existing installation space to achieve while keeping the cost of the battery as possible To keep it low, one strives to build the battery modular.

On the other side there are appropriate specifications, in particular from the power electronics, which increase the voltage limit. So typically 420V or 900V are considered limiting Voltages in power electronics usual. For this Reason must be the battery modules used in parallel or at least in blocks connected in parallel to this Voltage limit not to be exceeded.

Now it is with parallel connected batteries so that the current the Path of the lowest resistance, ie the lowest internal resistance, decreases. This can over the life of the battery to a strong divergence of the internal resistances and thus the capacities and the states of charge of the individual Lead batteries or battery modules. Unlike one serial connection of batteries or single battery cells, where the current flow through each cell is the same, so it comes in a parallel interconnection in practice to different Current flows in the different battery modules. This becomes a different burden and thus one lead to different aging of the battery modules. The different ones Aging of the individual battery modules, which are parallel to each other are interconnected, thus leading to an unequal distribution of internal resistances and capacity in the individual battery modules. This in turn leads to an uneven Distribution of the current flowing in the battery modules. This leads, at least in the case of the decrease in capacity, to a self-accelerating effect.

There the batteries or the battery modules in an electric vehicle or also in a hybrid vehicle a not inconsiderable part of Investing in the new vehicle is as well to strive for a long service life of the batteries. The effects described above act as intended long lifetime, however, massively contrary.

It Therefore, the object of the present invention is a battery to specify for the storage of electrical energy, which consists of several parallel connected battery modules, which are the above avoids problems mentioned and thus a long life of Battery allows. Furthermore, it is the task of here present invention to provide a corresponding method, which the operation of a battery consisting of several battery modules connected in parallel in the way that allows aging effects to a large extent balanced and a uniform load of individual battery modules can be achieved.

According to the invention this object by a battery with the features in the characterizing Part of claim 1 solved. Advantageous embodiments The battery will become apparent from the dependent claims 2 to 8. Furthermore, the object is achieved by a method with the features dissolved in the characterizing part of claim 9.

advantageous Embodiments of the method will become apparent from the dependent claims 10 to 20.

The Battery according to the invention has means by which the cooling of the battery modules depending on their aging state can be influenced. As explained above, run at the parallel connection of battery modules internal resistance, Capacity and aging of the individual battery modules very much slightly apart. The internal resistance as typical and easy measure of aging to be measured from the temperature of the battery. Because such high-performance batteries, such as lithium-ion batteries, anyway over an active cooling, for example with an aqueous Coolant based on water and antifreeze, or direct cooling with a climate medium of an air conditioning system, For example, R744 or R134a, can the individual battery modules easily according to their aging state be cooled. The invention Means then ensure that the cooling of the individual battery modules depending on their Aging condition can be influenced accordingly.

Therefor For example, it may be provided by the invention Mean coolant flows to the individual battery modules split accordingly, or the battery modules or their cooling devices on according to switchable lines so serially successively to flow through that the battery module which cooled the most is to be flowed through first while the Battery module, which should be cooled less, on End is flowed through. Besides that would be it is of course conceivable, also the flow temperature to influence the cooling accordingly, for example by a bypass guide around the cooling circuit, so that each of the battery modules with an individual flow temperature its cooling medium can be flown.

The inventive method looks accordingly Before that, the cooling of each battery module respectively depending on their state of aging. Therefor Essentially, what already applies above, in the description of the battery according to the invention, said accordingly has been.

When Measure of aging can be made according to one particular favorable embodiment of the invention Method used, for example, the size of the internal resistance become. However, it is also conceivable in an alternative embodiment of inventive method over the Life of the battery module to detect certain values and store, for example, the course of temperature and / or Load of the respective battery module. Out of these The life of the battery module stored data can then the state of aging is estimated accordingly, ie mathematically be determined. The cooling can then be dependent this aging condition take place.

Further advantageous embodiments of the invention Battery and the method according to the invention result from the embodiments illustrated below, which explained in more detail with reference to the accompanying figures are.

there demonstrate:

1 a diagram for the dependence of the internal resistance of a battery on the temperature;

2 a first embodiment of the battery according to the invention;

3 a second embodiment of the battery according to the invention;

4 a third embodiment of the battery according to the invention;

5 a fourth embodiment of the battery according to the invention; and

6 A fifth embodiment of the battery according to the invention.

In 1 measured values of the internal resistance R _{i are shown} above the temperature T of a battery or a battery module. The two curves show measured values of different battery modules, whereby it can be clearly seen that the dependence follows approximately the same course, even if the absolute values of the internal resistance R _i deviate slightly. This behavior of the internal resistance R _i , as an essential measure of the aging of a battery, is now exploited to parallel battery modules 1 . 2 a corresponding cooling of the individual battery modules 1 . 2 to realize depending on their state of aging. As a measure of the state of aging can be used in addition to the internal resistance R _i and another value, for example, a value which is a continuous storage and updating of, for example, temperature and / or load curves of the individual battery modules 1 . 2 can be calculated.

In 2 Now, a construction of the battery according to the invention is shown. This essentially shows the first battery module 1 and the second battery module 2 , These are electrically connected in parallel, which is not shown in detail in the figures. However, such a parallel connection of battery modules is assumed to be generally known and well-known.

The battery modules 1 . 2 should each be designed as lithium-ion batteries. These are actively coolable via a cooling device not explicitly shown here. Such a cooling device is known in principle from the prior art. It may for example be formed as a cooling plate, which on one side of the battery individual cells of such a battery module 1 . 2 is arranged. For example, the battery individual cells may be formed as Rahmenflachzellen, which are arranged on such a cooling plate. By means of heat-conducting elements, such as metallic cover plates of the frame flat cells, the heat can be dissipated from the battery individual cells into the region of this cooling device. The battery cells of the battery module 1 . 2 are connected in series, so that the same current flows through them. By way of example, for the construction of such a battery to the non-prepublished German application with the file number DE 10 2007 063 179.2 to get expelled.

In the figures is next to the battery modules 1 . 2 also a cooling circuit 3 to recognize which essentially consists of a corresponding piping, a coolant conveyor 4 and a cooling heat exchanger 5 for discharging the absorbed by a cooling medium energy, for example, to the environment exists. The cooling circuit 3 itself can be flowed through, for example, by an aqueous coolant, for example a mixture of water and an antifreeze, such as diethylene glycol. In addition, direct cooling via a climate medium, such as R744, R134a or CO ₂ , would be conceivable. In this case, the climate medium would then be in the range of the battery modules 1 . 2 evaporate accordingly. Here, too, a corresponding compression and recooling of the environmental medium is necessary, so that essentially a comparable structure of the cooling circuit 3 would arise. In the exemplary embodiments which are illustrated here, a cooling circuit with an aqueous coolant is to be used in each case for the sake of simplicity. It is clear to the person skilled in the art and understood that the abutments analogously also in the use of climate media, which in the field of battery modules 1 . 2 evaporate or at least partially evaporate, can be applied analogously.

In the presentation of the 2 are the two battery modules 1 . 2 now parallel to the cooling circuit 3 involved. Each of the cooling lines for the individual battery modules 1 . 2 has its own valve device 6 . 7 on. This valve device 6 . 7 For example, it can be designed as a controllable valve whose flow rate is continuously adjustable. Alternatively, it would also be conceivable to realize a structure in which the valve devices 6 . 7 are designed as clocked valves. In this case, the flow rate through the individual strands of the cooling circuit would be 3 for example, by a battery modulation of the pulse width ratio of the timing of individual valve devices 6 . 7 can be adjusted.

So it is now possible, via the valve devices 6 . 7 the volume flow of the coolant for the individual battery modules 1 . 2 over the valve devices 6 . 7 individually adapt. Therefore, by a corresponding control of the valve devices 6 . 7 a targeted cooling of the individual battery modules 1 . 2 independently of each other. In the construction according to the invention, the control of the valve devices 6 . 7 now depending on the aging of the battery modules 1 . 2 controlled or regulated. For example, the internal resistance R _{i of} the individual battery modules 1 . 2 measured and the battery module 1 . 2 with the lower internal resistance R _i , a larger amount of coolant is supplied, so that more cooling takes place. This ensures that the internal resistance R _{i of} the battery modules 1 . 2 align with each other and thus again a uniform flow of current and a uniform load on the two battery modules 1 . 2 can be achieved. Due to this more even current flow in the two battery modules 1 . 2 prevents further reduction of the internal resistance or capacity, so that the batteries are evenly loaded and thus age evenly. The structure of the battery as a whole can thus achieve a longer life.

In 3 an alternative embodiment is shown. Instead of the valve devices 6 . 7 here becomes a proportional valve 8th , used as a three-way valve. Otherwise, the structure in the representation of 3 with the 2 identical. Via the proportional valve 8th can now also the volume flow of the coolant, for example, based on the ratio of the internal resistance R _{i of} the battery modules 1 . 2 to the respective battery modules 1 . 2 be split. This in turn results in a more uniform load or charge and discharge of the individual battery modules 1 . 2 reaches the battery, so that the battery has a longer life overall.

In the presentation of the 4 is now a slightly different structure of the cooling circuit 3 to recognize. The individual battery modules 1 . 2 are in accordance with the execution 4 are not parallel to each other through the coolant, but are connected in series one behind the other and are flowed through by the coolant in a predetermined order. For this purpose, appropriate piping with multiple valve devices 9 . 10 such as 11 . 12 intended. Through these valve devices 9 . 10 . 11 . 12 , which may be formed, for example, as solenoid valves, the order of flow through the battery modules 1 . 2 be adjusted accordingly. If, for example, the valve device 9 opened while the valve device 10 is closed, it comes with simultaneous open valve device 11 and closed valve means 12 to a flow through the battery modules 1 . 2 in the order that first the first battery module 1 is passed through, while then the second battery module 2 is flowed through. Will the condition of all four valves 9 . 10 . 11 . 12 now changed, the coolant flows first over the valve device 10 through the second battery module 2 and then through the first battery module 1 , in reverse order and flow direction as before. Only then does the coolant flow over the valve device 12 back to the coolant conveyor 4 , By switching the valve devices shown here 9 . 10 and 11 . 12 Thus, a reversal of the flow can be achieved. In this construction, which is purely exemplary in its structural design, it is thus achieved that the battery modules 1 . 2 flows through in a predetermined order. comes it now leads to a corresponding divergence of the internal resistances R _{i of} the battery modules 1 . 2 Thus, the order of the flow can be adjusted to the ratio of the internal resistance R _i . In particular, the battery module 1 . 2 With the lower internal resistance R _{i are} first flowed through, so cooled by the colder coolant than the battery module 2 . 1 with the higher internal resistance R _i . If the internal resistances R _i adjoin one another, or if the ratio of the internal resistances R _i reverses, the sequence of the flow through the individual battery modules also changes 1 . 2 also adapted or vice versa.

A further embodiment variant of the construction of the battery according to the invention is shown in FIG 5 to recognize. Again, the battery modules 1 . 2 flows through the coolant in series. This is the first battery module 1 however, a bypass line 13 with a valve device 14 realized. Through this bypass line 13 may vary depending on the opening of the valve 14 which in turn may be designed as a clocked valve or as a proportional valve, a corresponding flow around the battery module 1 be reached by the cold coolant. After flowing through the first battery module 1 This will be done by the battery module 1 flowing coolant with the through the bypass line 13 flowing coolant is mixed again before the second battery module 2 flows through. As a result, the temperature of the coolant when flowing into the second battery module 2 to some extent through the valve 14 in the bypass line 13 customizable. Likewise, by the bypass line 13 and the valve 14 in the area of the first battery module 1 adjusted cooling capacity adjusted. Alternatively or additionally, a further bypass line including valve could also be around the second battery module 2 be provided to adjust the realized cooling capacity here too. Also, the adjustments in this constructive embodiment, in turn, depending on the aging state, for example, based on the internal resistance of the individual battery modules 1 . 2 , respectively. For this purpose, a map may be stored in a control electronics, which implements the adaptation. Alternatively, a corresponding simulation calculation would be conceivable which provides suitable values for the adaptation.

In 6 Now another alternative embodiment is shown. Here is a bypass line 15 around the cooling heat exchanger 5 realized. This bypass line 15 then divides into two strands 16 . 17 on, which in each case via a valve device 18 . 19 feature. The one strand 16 runs with the coolant line to the first battery module 1 together, while the other strand 17 with the coolant line for the second battery module 2 converges. Because now heated, not in the cooling heat exchanger 5 cooled coolant can be mixed with cooled coolant, depending on the opening of the valve devices 18 . 19 , the flow temperature of the coolant for the individual battery modules 1 . 2 be set individually. This then takes place in turn depending on the aging state or the internal resistance R _{i of} the individual battery modules 1 . 2 , In this way, it is also possible to realize such a design which the individual battery modules 1 . 2 each cools depending on their aging state accordingly, so that despite different internal resistance R _i and capacitors uniform loading of the battery modules 1 . 2 with the current when charging or discharging the battery occurs. This in turn leads to a homogenization of the aging of the individual battery modules 1 . 2 among themselves. This can be prevented that individual battery modules 1 . 2 due to a corresponding aging and overloading fail prematurely. Overall, thus also a longer life of the battery can be achieved.

The illustrated embodiments of the invention Battery are to be understood as an example. Especially can also have more than two battery modules in parallel be interconnected to the total battery. Again, essentially apply the same designs. It is also conceivable, a parallel connection and a serial connection of the cooling devices of to combine individual battery modules accordingly, so for example in several parallel strands in each case several serially flowed through battery modules are arranged. these can then in a fixed or possibly also a changeable one Flow through sequence. Here are individual or all elements are provided with bypass lines, which either around the cooling heat exchanger and / or the battery modules lead yourself.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102007063179 [0023]

Claims (20)

Battery for storing electrical energy, having at least two battery modules, which are electrically connected in parallel, with at least one cooling device for active cooling of the battery modules, characterized in that means are provided, by which the cooling of the battery modules ( 1 . 2 ), in each case depending on their state of aging can be influenced. Battery according to claim 1, characterized in that the means in dependence of the internal resistance (R _i ) of the respective battery module ( 1 . 2 ) are driven. Battery according to claim 1 or 2, characterized in that the battery modules ( 1 . 2 ) each have at least one cooling device, which can be flowed through by a cooling medium flow. Battery according to claim 3, characterized in that the means as at least one valve device ( 6 . 7 . 8th ) are formed, through which the cooling medium flow can be divided in different flow rates on the cooling devices. Battery according to claim 3 or 4, characterized in that the means at least one controllable bypass line ( 13 . 15 ) around at least one of the battery modules ( 1 . 2 ) and / or a cooling heat exchanger ( 5 ) for cooling the cooling medium stream. Battery according to claim 5, characterized in that the bypass line ( 15 ) around the cooling heat exchanger ( 5 ) is formed, and that the bypass line ( 15 ) via at least one further valve device ( 17 . 19 ) is connected to at least some of the cooling devices. A battery according to claim 3, characterized in that the cooling means are flowed through by the cooling medium flow successively, wherein the means conduit member and valve means ( 9 . 10 . 11 . 12 ), which allow a change in the order of flow. Battery according to one of claims 1 to 7, characterized by the formation as a lithium-ion battery. Method for operating a battery for storing electrical energy, which is divided into at least two battery modules, which are electrically connected in parallel, wherein an active cooling of the battery takes place, characterized in that the cooling of the individual battery modules ( 1 . 2 ) takes place depending on their state of aging. A method according to claim 9, characterized in that the aging state of the respective battery module ( 1 . 2 ) is estimated on the basis of the internal resistance (R _i ). Method according to claim 10, characterized in that the battery module ( 1 . 2 ) are cooled more strongly with lower internal resistance (R _i ) than the battery module ( 1 . 2 ) with greater internal resistance (R _i ). Method according to claim 9, aging state of the respective battery module ( 1 . 2 ) is estimated by calculation over the life of the battery module recorded and stored data. A method according to claim 12, characterized in that the data at least one of the courses of temperature (T) and / or load of the respective battery module ( 1 . 2 ). Method according to one of claims 9 to 13, characterized in that the targeted cooling for each battery module ( 1 . 2 ) is done by a division of cooling medium streams on cooling devices of each battery module ( 1 . 2 ). Method according to claim 14, characterized in that the battery modules ( 1 . 2 ) are cooled by cooling medium streams with different volume flows. Method according to claim 14, characterized in that the battery modules ( 1 . 2 ) of cooling medium streams at different temperatures (T) are cooled. Method according to one of claims 9 to 13, characterized in that the targeted cooling for each battery module ( 1 . 2 ) by adjusting the order of cooling of each battery module ( 1 . 2 ) takes place with the cooling medium flow. Method according to one of claims 9 to 17, characterized in that the targeted cooling for each battery module ( 1 . 2 ) by adjusting the volume flow and / or the temperature (T) of the cooling medium flow by at least partially guiding the cooling medium flow in controllable bypass lines ( 13 . 15 ) to one or more of the battery modules ( 1 . 2 ) and / or a cooling heat exchanger ( 5 ) to cool the coolant takes place. A method according to claim 18, characterized in that the cooling medium flow at least partially in a bypass line ( 15 ) is guided around the cooling heat exchanger, and that in the bypass line ( 15 ) guided portion of the cooling medium flow with one or more of the cooling medium streams to the respective battery modules ( 1 . 2 ) is mixed. Method according to one of claims 9 to 19, characterized in that the battery is a lithium-ion battery is used.

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