WO2013083491A1 - Energy storage system comprising an electrical energy store and a temperature monitoring device - Google Patents

Abstract

The invention relates to an energy storage system which comprises an electrical energy store and a temperature monitoring device. According to the invention, simple yet reliable temperature monitoring can be achieved in an energy storage system (10) that comprises at least one electrical energy store (12) with electrically-interconnected storage units (14), and a monitoring device (13) for monitoring the temperature of said storage units (14), when said monitoring device (13) comprises a temperature sensor (20) which is connected to a plurality of the storage units (14) in a thermally conductive manner via a "thermal connector arrangement" (30) and which is therefore used to simultaneously monitor the temperature of the storage units (14).

Description

description

Energy storage system comprising an electrical energy storage and a temperature monitoring device

The present invention relates to energy storage systems that can be used in particular in vehicles that are wholly or partially or situation-driven by electrical energy. These include, for example, hybrid and electric vehicles, in which the energy storage system represents the so-called traction battery.

In particular, the invention relates to an energy storage system, comprising at least one electrical energy store with a plurality of storage units connected in series and / or in parallel, and a monitoring device for monitoring the temperature of the storage units.

The storage units which are electrically interconnected in the energy store may in particular be electrochemical battery cells (eg nickel-metal hydride, nickel-zinc, lithium-air, zinc-air or lithium-ion cells). Alternatively or additionally, it may, for. B. also be capacitors (eg., So-called double-layer capacitors or the like) act.

The monitoring device can, for. B. be implemented as a part or a partial functionality of a complex monitoring device of the energy storage system, by means of which not only the temperature monitoring of the memory units but also other control and / or monitoring functions are accomplished. An example of this is the monitoring of electrical states of charge of individual storage units and a homogenization of these states of charge based thereon ("Balancing")

Both for the proper function and for the life of the individual storage units, it is in practice of great importance that they are operated in a certain allowable temperature range.

Since the storage units heat more or less strongly during charging and discharging, active and / or passive cooling measures are usually provided in order to avoid excessive heating or overheating of individual storage units.

For example, electrochemical storage cells can often form flammable gases (eg, hydrogen) if the cell temperature is too high, so that in addition to the risk of irreversible damage to the relevant cells, there is also the risk of fires or explosions consists.

Against this background, the mentioned temperature monitoring of the memory units is advantageous in that it enables early critical operating situations or defects to be detected by exceeding certain temperature limits.

To realize the temperature monitoring, it is known from the prior art of traction batteries to arrange temperature sensors on the memory cells of the energy store. Thus, the temperatures of those cells can be measured, on each of which a temperature sensor is arranged. The temperature measurement signals supplied by the temperature sensors can be routed via a suitable electrical line arrangement to an evaluation electronics and evaluated there.

A disadvantage of the above-described "individual In particular, the expense of providing a greater or lesser number of temperature sensors, including the line connection of these sensors to the evaluation electronics, is even greater if, for example, for reasons of safety, a certain temperature (eg a certain temperature) is reached If, for example, several temperature sensors are placed at different locations of a cell for this purpose, such a redundancy is achieved, on the other hand, however, further additional costs are caused.

For cost reasons, therefore, the measurement of the individual temperatures of all cells is usually dispensed with, in order instead to measure only a few individual temperatures at "pilot cells".

However, this cost-reducing approach results in "monitoring gaps" in the sense that overheating of a single cell, at which no temperature sensor is provided, may not be recognized or detected very late. However, as already mentioned, such overheating can endanger the relevant cell (s) or the entire energy store.

The more temperature sensors are saved in the previous monitoring concepts, the greater the risk that critical operating conditions or defects are not detected or only too late.

It is therefore an object of the invention to enable a simple yet reliable temperature monitoring in an energy storage system of the type mentioned. This object is achieved in the energy storage system according to the invention in that the monitoring device comprises a temperature sensor, which is thermally conductively connected via a thermocouple arrangement with a plurality of storage units and thus used for simultaneous temperature monitoring of these storage units.

The term "thermal conductor arrangement" is intended here to designate a heat-conducting arrangement, which is connected on the one hand thermally conductive to the relevant temperature sensor and the other heat-conducting to the respective storage units, and (as described below) may comprise one or more "thermal conductors".

Even if, for example, only one of the storage units connected to the thermal conductor arrangement has an excessively high temperature, this can advantageously be detected reliably by means of the temperature sensor due to the capability of the thermal conductor arrangement for the transmission of temperature or the transfer of heat. This is advantageous regardless of which of the plurality of thermally bonded storage units has the excessive temperature.

The use according to the invention of a temperature sensor for the simultaneous temperature monitoring of several storage units advantageously leads to a more or less drastic reduction in the number of required temperature sensors (depending on how many storage units are connected to a temperature sensor via the thermal conductor arrangement).

Compared to a conventional arrangement of one temperature sensor per storage unit to be monitored, the solution according to the invention, while providing a "resolution Information "is lost when it is not readily apparent when detecting an over-temperature, by which of the temperature sensor connected storage unit (s) this detection was triggered.The point is, however, that a knowledge of this resolution information in practice of rather subordinate The decisive advantage of the invention is that, given a given number of temperature sensors, the occurrence of an excess temperature for a comparatively large number of storage units can be detected reliably or requires comparatively few temperature sensors for a given number of storage units to be reliably monitored for overtemperature become.

In particular, the invention thus makes it possible to reduce or even completely avoid the "monitoring gaps" mentioned above.

In one embodiment, it is provided that the temperature sensor is connected to at least three, in particular at least five, of the storage units in a heat-conducting manner.

Depending on the "topology" or design of the thermal conductor arrangement, it may be that the reliability of the temperature monitoring suffers somewhat when a large number of memory units are thermally connected to one and the same thermal conductor arrangement. In this case, this number should not be too large. On the other hand, the greater the number of memory units connected to a temperature sensor, the greater the saving of temperature sensors. For this reason, with sufficiently good thermal conductivity of the thermal conductor arrangement, the connection of an even larger number of memory units than stated above can certainly be provided. In particular, z. B. all the energy storage storage units (eg., More than 20) to one and the same Thermoleiteranordnung be connected, said thermal conductor arrangement in turn with a single temperature sensor (or alternatively with a plurality of temperature sensors) may be thermally connected.

Each storage unit, so z. B. electrochemical battery cell or capacitor, has a memory unit body, in which the actual energy-storing components are housed, and at least two leading out of the interior of the body electrical conductor, so-called "Abieiter" (representing the positive pole or negative pole of the memory unit).

In one embodiment, it is provided that at least one of the storage units in the region of a storage unit body is heat-conductively connected to a section of the thermal conductor arrangement. In the case of an arealwide storage unit (for example, so-called "flat cell"), this connection takes place, for B. preferably in a central region of the storage unit body. When forming the energy storage device from a plurality of storage units of extended area, they can be stacked to form a block with the interposition of cooling plates. In this case, the heat-conducting connection of a storage unit body can be realized in particular via an immediately adjacent (flat-fitting) such heat sink.

Alternatively or additionally, at least one of the storage units in the region of a storage unit removal unit may be connected in a heat-conducting manner to a section of the thermal conductor arrangement. To use such a Abieiter as a thermal connection point is interesting in that Abieiter in addition to the required good electrical conductivity usually also have a good thermal conductivity, and also extend into the interior of the storage unit, so that a first in the interior of the storage unit itself developing Overheating also very quickly leads to a temperature increase of the Abieiter (also outside of the actual memory unit body).

If the thermally connected to a Abieiter "thermal conductor" of the thermal conductor assembly as such has a significant electrical conductivity, which z. B. in the formation of the thermal conductor of a metallic material is the case, it can be provided to avoid unwanted electrical effects (short circuits between different Abieitern etc.) that the corresponding connection point of the thermocouple is not directly and thus electrically connected to the Abieiter, but with the interposition of a thermally but not electrically conductive intermediate layer (eg., Suitable thermally conductive plastic).

For a space-saving design of the thermal conductor arrangement, it is advantageous if this comprises at least one elongated thermocouple section, so z. B. a thermal conductor, which is formed as a profile or a wire. With regard to the lowest possible heat losses in the heat transfer is provided according to an advantageous embodiment, that the elongated thermal conductor section has a round, in particular circular cross-section. Alternatively or additionally, it may be advantageous under certain circumstances if at least one elongated thermo-conductor section has a cross-sectional area varying along its length. Alternatively or additionally, it can also be provided that individual thermal conductor sections or the entire thermal conductor arrangement is provided with a thermal insulation (sheathed).

As already mentioned, a thermal conductor section or the entire thermal conductor arrangement z. B. be formed of a metallic material, optionally with a thermal insulation z. As plastic, to prevent or reduce heat exchange between the heat-conducting material and the environment.

In one embodiment, it is provided that a plurality of spaced-apart connection points for heat-conducting connection of various of the storage units are provided along the elongated thermal conductor section. It is thus by no means necessary for each storage unit to be monitored to lay its own thermal conductor over a greater distance in the direction of the temperature sensor. Rather, one and the same elongated thermal conductor can be laid and thermally connected to a plurality of storage units, that this thermal conductor in a sense "heats up the heat of the individual storage units" and "bundled" forwards the temperature sensor.

In one embodiment, it is provided that the thermal conductor arrangement has at least one node and / or at least one mesh. The terms "knot" and "mesh" are to be understood in a topological sense. A node is therefore present when at least three thermal conductors meet at one point of the thermal conductor arrangement. Such a node could therefore also be referred to as a branching point or merging point of the thermal conductor arrangement. A mesh exists if there is a ring-shaped closed thermo-conductor section.

In a more specific embodiment, the thermal conductor assembly has at least one node but no mesh. In this case, z. B. starting from several storage units respective thermal conductors first lead to a "collecting node", from which in turn a single thermal conductor continues to the temperature sensor. Such heat fusion can also take place in several stages, for example, starting from two or more of the mentioned collecting node respective thermal conductors do not run as such to the temperature sensor, but to a "parent collecting node" (which in turn is connected by a thermal conductor to the temperature sensor).

A thermal conductor assembly having a plurality of nodes and a plurality of meshes may e.g. B. may be provided as a net-like structure which covers the storage units of the energy storage in a sense, so that a material-saving, yet efficiently thermally conductive thermal conductor arrangement is provided.

A particularly preferred use of an energy storage system of the type described above is the use as a traction battery for a vehicle equipped with an electric drive, in particular a road vehicle.

The invention will be further described by means of embodiments with reference to the accompanying drawings. They show:

1 is a schematic plan view of an energy storage system according to an embodiment,

Fig. 2 is a representation corresponding to FIG. 1 a

 Energy storage system according to another embodiment, and

Fig. 3 is a perspective view of a detail of a

Energy storage system according to another exemplary embodiment. 1 illustrates an energy storage system 10, here for example a traction battery of a hybrid vehicle, comprising an electrical energy store 12 and a monitoring device 13 assigned to it.

In the exemplary embodiment illustrated, the energy store 12 comprises a multiplicity of memory cells 14 which are connected electrically in series in the form of so-called electrochemical flat cells, which are to be understood here as substantially flat-shaped memory cells. The memory cells 14 (eg, lithium-ion cells) have an approximately rectangular format and are stacked with mutually facing flat sides combined to form a "cell block". The series electrical connection is accomplished by conductor 16, each memory cell 14 having two, a "negative pole" and a "positive pole". The conductors 16, which are already contacted in pairs (eg, soldered or welded to one another) or connecting lugs of the individual memory cells 14, are shown in FIG.

The negative pole and the positive pole of the illustrated overall arrangement (energy store 12) is marked in FIG. 1 with the symbol "-" or "+". During operation of the energy storage system 10, charging and discharging of the energy store 12 can take place via these two poles.

The number, design and arrangement or electrical connection of the memory cells 14 can be modified differently from the illustrated example in many ways. Also, an energy storage system can do more than just a cell block

(Energy storage 12), wherein a plurality of such cell blocks, for example, in turn, can be electrically connected in series and / or in parallel. In the context of the invention is particularly essential that the energy storage system 10 the has mentioned monitoring device 14, which (at least) is designed for temperature monitoring of the memory units 14, and that this temperature monitoring is implemented in a particular manner described in more detail below.

A special feature of the monitoring device 14 is that it comprises a temperature sensor 20, which in the example shown z. B. is designed as a semiconductor sensor and a sensor signal line 22 with an electronic

Evaluation device 24 is connected, and that the temperature sensor 20 via a "thermocouple assembly" 30, which is formed in the illustrated example of a single "thermal conductor" 32, with a plurality of (in the example all) of the memory cells 14 thermally conductive and thus for simultaneous temperature monitoring of these memory cells 14 is used.

The temperature sensor 20 is arranged, for example, together with the evaluation electronics 24 on a circuit board, which is integrated in a housing of the electrical energy storage 12 or energy storage system 10.

In contrast to known temperature monitoring concepts, the temperature sensor 20 is thus not arranged so that the temperature in the region of one of the memory cells 14 could be measured directly. Rather, a measurement is carried out by means of the temperature sensor 20 in an indirect manner, namely on the thermal conductor assembly 30, with which a "temperature transmission path" between the memory cells to be monitored 14 on the one hand and the temperature sensor 20 on the other hand is realized.

The thermal conductor 32 is for this purpose made of a good heat conducting material such. B. copper or alloy formed and on the one hand via thermal connection points 34 with the memory cells 14, in fact with a number of their Abieitern 16 (left in Fig. 1) thermally conductively connected and on the other hand via a thermal connection point 36 thermally conductively connected to the temperature sensor 20.

If an excessively high temperature occurs at one or more of the memory cells 14 during operation of the energy storage system 10, this leads to a corresponding heating of one or more of the absorber 16, which in turn leads to heating of the thermal conductor 32 via the thermal connection points 34. This heating finally transfers via the connection point 36 as far as the temperature sensor 20. Using the sensor signal supplied by the temperature sensor 20, a common temperature monitoring of all the memory cells 14 can thus advantageously be carried out in a simple manner. If an excessively high temperature is detected with the temperature sensor 20, suitable measures can be triggered by means of the evaluation electronics 24 (eg, memory shutdown, active cooling, power reduction, etc.) so that a predetermined permissible temperature range is reached again by such countermeasures.

For a pure safety monitoring of the memory cells 14, an exact knowledge of the individual cell temperatures is irrelevant, as long as it is only important that all cell temperatures are within a predetermined permitted range. In this case, the monitoring function can be reduced substantially to a threshold value monitoring, which responds to the exceeding of a predetermined temperature limit. This "simplified monitoring function" is achieved in an elegant manner by the use according to the invention of the thermocouple arrangement 30 in conjunction with a simple "comparator function" of the evaluation device 24. lisiert. The temperature monitoring according to the invention has advantageous redundancy insofar as a critical operating situation, which is manifested by an excessive rise in the temperature in a specific region of the energy store 12, is detected reliably.

In the simplest case takes place in the transmitter 24, a comparison of the temperature measured by the sensor 20 with a predetermined temperature limit (threshold). If this threshold is exceeded, the mentioned countermeasures can be initiated, for. B. activated a cooling circuit or the energy storage system 10 are turned off.

In the exemplary embodiment shown, the temperature sensor 20 is advantageously connected to a larger number of memory cells 14 (eg more than 20), so that advantageously many temperature sensors are saved (in comparison to an arrangement of one temperature sensor per cell to be monitored). The thermal connection points 34 are provided in the example shown on the (electrically conductive) Abieitern 16 of the respective memory cells 14. To thereby avoid short circuits between these Abieitern 16, an electrical insulation of the thermal conductor 32 is provided at least in the region of each attachment point 34. This isolation can z. Example, as an interposition of a good heat-conducting, but electrically insulating plate or material layer (eg., Adhesive layer) between Abieiter 16 and thermal conductor 32 are accomplished (eg., Thermally conductive plastic).

Deviating from the illustrated example, alternatively or in addition to the illustrated thermal conductor 32 such a thermal conductor could also be thermally connected to suitable other locations of the respective memory cells 14, which under Circumstances do not require the mentioned electrical insulation (eg in the region of an electrically insulating enclosure of the respective memory cells 14). If the memory cells 14 are stacked with the interposition of (not shown in Fig. 1) cooling plates, which are each in surface heat conduction contact with the two immediately adjacent memory cells 14, so thermal connection points can be provided in particular on these cooling plates. In the example shown in FIG. 1, the thermocouple assembly 30 includes only a single elongate thermoconductor section in the form of the thermocouple 32. In the embodiments described below, a plurality of "thermal conductors" are used.

In the following description of further embodiments, the same reference numerals are used for equivalent components, each supplemented by a small letter to distinguish the embodiment. In this case, essentially only the differences from the embodiment (s) already described are discussed and, moreover, reference is hereby explicitly made to the description of previous exemplary embodiments. FIG. 2 illustrates a modified embodiment of an energy storage system 10a.

The system 10a initially includes all of the components already described for the system 10 of FIG. In addition, however, a thermal conductor arrangement 30a of the system 10a comprises, in addition to a first thermal conductor 32a, a second thermal conductor 32a ', likewise designed as an elongated thermoelectric conductor portion, by means of which in the illustrated example an additional temperature monitoring is implemented to increase the redundancy.

As in the case of the first thermal conductor 32a, a plurality of mutually spaced connection points 34a 'are provided along the second thermal conductor 32a' for thermally conductive connection of various (in this case all) of the memory cells 14a. However, these connection points 34a 'are arranged on the other side (on the right in FIG. 2) of the memory cells 14a, with a second temperature sensor 20a' (on the same circuit board as the first temperature sensor 20a) being provided for the second temperature measurement increasing redundancy in the illustrated example and via a second temperature sensor 20a ' another sensor signal line 22a 'is connected to the evaluation device 24a.

By means of a comparison of the two temperature measured values carried out by means of the evaluation electronics 24a, it is also possible, for example, to advantageously diagnose a malfunction of the temperature monitoring (if the two measurement results deviate excessively from one another).

Deviating from the illustrated example with its own temperature sensor 20a ', the second thermal conductor 32a' could also be connected to the first temperature sensor 20a, for example directly by arranging both thermal connection points 36a and 36a 'on the sensor 20a. Alternatively, the thermocouple assembly 30a could be formed with a node (branch), which is thermally conductively connected on the one hand to the sensor 20a and on the other hand with the two extending over the memory cells 14a thermocouple sections of the thermal conductors 32a and 32a '.

In all energy storage systems according to the invention, conventional concepts for the temperature Monitoring be used. In particular, it is by no means impossible, and often even advantageous, if at least some of the memory units ("pilot memory units") are provided with at least one temperature sensor measuring the temperature there directly. This optional further development is shown dashed in the figure for the embodiment of FIG. An additional temperature sensor 20a "is connected to the evaluation electronics 24a via an electrical sensor signal line 22a". In an analogous manner, even more of the existing memory cells 14a may be equipped with such a separate, direct temperature detection.

If along an elongated thermal conductor section a plurality of spaced-apart connection points for thermally conductive connection of various storage units are provided on the same thermal conductor section, as z. Example, in the embodiments described above, it is an additional advantage that with the relevant thermal conductor section (see, the thermal conductors 32 and 32 a and 32 a ') an additional temperature exchange path between the respective storage units (see. 14a). This advantageously promotes a homogenization of the spatial temperature distribution of the relevant energy storage.

With regard to such a temperature exchange as well as a particularly reliable detection of an excess temperature at any point of the relevant energy storage can also be provided that the thermal conductor arrangement several, in particular all storage units "net-like" covers. The thermal conductor arrangement can therefore z. B. have multiple nodes and multiple meshes (in the topological sense). A corresponding embodiment will be explained below with reference to FIG. In the embodiments of FIGS. 1 and 2, each thermocouple assembly is thermally connected to only one temperature sensor. Deviating from this, according to a development, a thermal conductor arrangement is provided, which is thermally connected to at least two temperature sensors, wherein these temperature sensors are preferably located at different locations of the thermal conductor arrangement. So z. 1, that the thermal conductor 32 is extended downward in FIG. 1 and leads to a second temperature sensor, which has a second sensor signal line with its own evaluation device or preferably the evaluation device 24, which is present anyway connected is. Alternatively or additionally, further temperature sensors arranged distributed over the length of the thermal conductor 32 can also be used in the example of FIG. 1. Such embodiments advantageously allow to obtain an at least approximate "resolution information" concerning the location of the storage units having excessive temperature.

FIG. 3 shows a memory cell 14b of an energy storage system, which is not shown in its entirety, which is similar to the exemplary embodiment according to FIG. 2 in that two thermal conductors 32b and 32b 'extending in the stacking direction over a cell block are provided therein.

In addition, however, further thermal conductor sections 33b are laid as "cross connections" between the thermal conductors 32b and 32b 'and are thermally connected via connection nodes 35b.

Apart from the function of the further thermal conductor sections 33b for connecting the "longitudinal" thermal conductors 32b and 32b ', these can also be used to further heat To provide transition parts for transferring heat from a memory cell in the thermal conductor assembly 30 b.

For example, the middle in Fig. 3 thermal conductor 33b also z. B. be thermally conductively connected over a majority of its length with the body of the illustrated memory cell 14b, to effect a heat transfer from this body to the two longitudinal thermal conductors 32b and 32b '.

Alternatively or additionally, a Abieiter a memory cell may be thermally connected to a transverse thermal conductor 33 b, as z. B. for the upper in Fig. 3 thermal conductor 33 b is shown. In this example, a middle portion of the transverse thermal conductor 33b is effectively formed by the depicted conductor 16b itself, to which two thermal bonding sites 34b are provided. As an alternative to these two separate connection points 34b, the relevant thermal conductor 33b could also be provided running continuously and be thermally connected to the surface of the conductor 16b in the region of its length running across the conductor 16b (possibly via an electrically insulating intermediate layer).

According to the connection principle illustrated with FIG. 3, an arbitrarily dense network of thermal conductors can thus be realized, whereby the possibility arises of detecting the maximum temperature of all the memory cells. The redundancy of the temperature monitoring is thus advantageously increased and there is an additional heat exchange at the memory cells.

Even with a "net-like" configuration of the thermal conductor arrangement, as illustrated in FIG. 3, it is possible to provide this thermal conductor arrangement with more than one temperature sensor. In the example of FIG. For example special four temperature sensors are arranged on the four "temperature conductor network".

Claims

Energy storage system (10), comprising - At least one electrical energy store (12) having a plurality of memory units (14) connected in series and / or in parallel, and - A monitoring device (13) for monitoring the temperature of the memory units (14), characterized in that the monitoring device (13) comprises a temperature sensor (20), the thermally connected via a thermal conductor arrangement (30) with a plurality of memory units (14) and thus to simultaneous temperature monitoring of these memory units (14) is used. Energy storage system (10) according to claim 1, wherein the temperature sensor (20) with at least three, in particular at least five of the storage units (14) is thermally conductively connected. Energy storage system (10) according to one of the preceding claims, wherein at least one of the storage units (14) in the region of a storage unit body is thermally conductively connected to a portion of the thermal conductor arrangement (30). Energy storage system (10) according to one of the preceding claims, wherein at least one of the storage units (14) in the region of a Speicherseinheitabieiters (16) is thermally conductively connected to a portion of the thermal conductor assembly (30). Energy storage system (10) according to one of the preceding claims, wherein the thermal conductor arrangement (30) at least one elongated thermal conductor section (32, 33) comprises. An energy storage system (10) according to claim 5, wherein said elongate thermocouple portion (32, 33) has a round cross-section. An energy storage system (10) according to claim 5 or 6, wherein the elongate thermoconductor section (32, 33) is formed of a metallic material. Energy storage system (10) according to any one of claims 5 to 7, wherein along the elongated Thermoleiterabschnittes (32, 33) a plurality of spaced-apart connection points (34) are provided for thermally conductive connection of various of the storage units (14). Energy storage system (10) according to one of the preceding claims, wherein the thermal conductor arrangement (30) has at least one node and / or at least one mesh. Use of an energy storage system (10) according to one of the preceding claims as a traction battery of a vehicle equipped with an electric drive.