AU2010257718B2

AU2010257718B2 - Method for operating a high-performance battery and device suitable for carrying out said method

Info

Publication number: AU2010257718B2
Application number: AU2010257718A
Authority: AU
Inventors: Rainer Hartig
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2009-06-12
Filing date: 2010-05-14
Publication date: 2014-03-06
Anticipated expiration: 2030-05-14
Also published as: KR101309986B1; AU2010257718A1; DE102009024657A1; KR20120025514A; WO2010142511A3; EP2441149A2; WO2010142511A2

Abstract

The invention relates to a method for operating a high-performance battery (6) which comprises a plurality of rows (10), connected in parallel, of a plurality of battery units (11, 12) which are each connected in series. At least one reference value of the battery (6) is measured and an anticipated profile (45) of the battery (6) relative to a physical parameter of the battery units (11, 12) is deduced therefrom. Current values of the physical parameter of the battery units (11, 12) are measured using Bragg grating sensors (20) and a current profile (40) of the battery (6) relative to the physical parameter is deduced therefrom. The current profile (40) is then compared to the anticipated profile (45) and the operation of the battery (6) is controlled and/or regulated depending on a deviation from the anticipated profile (45).

Description

1 Description Method for operating a high-performance battery and device suitable for carrying out said method TECHNICAL FIELD The invention relates to a method for operating a high- performance battery and a device suitable for carrying out said method. BACKGROUND High-performance batteries currently being developed on the basis of, for example, Li-ion battery cells, Li-polymer cells, Li-iron-phosphate battery cells, Li-titanate battery cells and combinations thereof distinguish themselves, in comparison with conventional batteries, such as lead-acid batteries, by having significantly shorter charging and discharging times and a significantly increased short-term discharge current. What is regarded as problematic, however, for their use in a direct current internal power supply system configured as a large-scale installation, for example, in an internal power system for a power station or in a submarine DC supply network, is the extraordinarily large possible short-circuit currents which can reach, for example, 20kA for a battery bank and up to 500kA per battery. A high-performance battery in a DC internal power supply system usually consists of a plurality of battery modules connected in parallel, each having one bank or a plurality of parallel connected banks of high-performance battery cells connected in series wherein the bank, or each of the banks, has the supply voltage of the DC internal power supply system. For the switching of the operating currents and limiting the short-circuit currents, a battery system in a DC internal power supply system usually also has a switching device. An internal power supply with a high performance battery and a 7938069_1 2 switching device of this type is disclosed, for example, in EP 1 641 066 A2 and WO 2008/055493 Al. High-performance lithium-ion battery cells and modules for use in supply systems of this type are known, for example, from the article "Development of High-Energy Lithium-Ion Cells" by K. Brandt and S. Theuerkauf in "Naval Forces Special Issue 2007", page 109. In order to prevent overload, short-circuits and general damage to the battery and the battery modules, suitable monitoring and safety functions are required. At the same time, the battery and the individual modules or cells thereof should be optimally operated in the charging and discharging cycles thereof. For this purpose, also, suitable monitoring and control functions are needed. The monitoring, control and safety functions must be carried out in short-circuit proof embodiments, since otherwise these functions themselves pose dangers. For the use of the battery in a vehicle, particularly an aquatic vehicle, the equipment needed for this purpose must be characterized by robustness, low susceptibility to electromagnetic disturbance, a compact design and low weight. KR 812742 Bl discloses, in a battery having a plurality of battery cells connected in series, the monitoring of the temperature of the individual battery cells with Bragg grating sensors. The Bragg grating sensors are arranged in a waveguide which extends along the battery cells and is connected to the battery cells in the region of the current terminals thereof. SUMMARY A need exists for a high-performance battery with a plurality of battery banks and battery cells and consequently a relatively large spatial extent, to 7938069_1 3 provide an operating method which enables safe, optimum operation of the battery, particularly for use of the battery in an internal DC power supply system, for example, in an aquatic vehicle. A need also exists for a device that is particularly suitable for carrying out said method. The need relating to the method is addressed through a method described herein. Advantageous embodiments are also described. A device that is particularly suitable for carrying out the method is also described herein. Advantageous embodiments of the device are the subject matter of further description. A first aspect of the present invention provides a method for operating a high-performance battery comprising a plurality of parallel-connected banks of battery units connected in series, the method comprising: - measuring actual values of a physical parameter of the battery units with the aid of Bragg grating sensors and deriving an actual profile of the battery relative to the physical parameter from the measured actual values,- measuring at least one reference variable of the battery and deriving an anticipated profile of the battery relative to the physical parameter of the battery units from the measured at least one reference variable based on profiles previously determined by calculation and/or experiment and stored in a control device of the battery, said profiles each being allocated to different measurement values of the at least one reference variable, comparing the actual profile with the anticipated profile, and controlling and/or regulating the operation of the battery depending on any deviation of the actual profile from the anticipated profile. A further aspect of the present invention provides a device for carrying out the method of the first aspect, said device comprising at least one Bragg grating sensor for measuring a value of at least one reference variable of the battery, -for each of the battery units, at least one respective Bragg grating sensor for measuring an actual value of a physical parameter of the battery unit, a control and/or regulating device configured such that said device a) derives from the measurement value of the reference variable an anticipated profile of the battery relative to a physical parameter of the battery units, b) derives from the measured actual values of the physical parameter of the battery units an actual profile of the battery relative to the physical parameter, c) compares the 7938069_1 3a actual profile with the anticipated profile and d) controls and/or regulates the operation of the battery depending on a deviation of the actual profile from the anticipated profile. In the disclosed method for operating a high-performance battery, wherein the battery comprises a plurality of parallel-connected banks of battery units (e.g. battery modules or battery cells) connected in series, at least one reference variable of the battery is measured and an anticipated profile of the battery relative to a physical parameter of the battery units is derived therefrom. The physical parameter may be, for example, a temperature, expansion or vibration of a battery unit. In addition, actual values of the physical parameter of the battery units are measured with the aid of Bragg grating sensors and an actual profile of the battery relative to the physical parameter is derived therefrom. The actual profile is compared with the anticipated profile and the operation of the battery is controlled and/or regulated depending on any deviation from the anticipated profile that is determined. Since a plurality of Bragg grating sensors can be arranged in a common light waveguide, the recording of the measured values is possible with a relatively small cabling effort and 7938069_1 4 therefore a low weight and space requirement, even for a battery with a plurality of banks and cells. The recording of measurement values based on Bragg grating sensors and light waveguides is also characterized by protection against short circuits, insensitivity to electromagnetic disturbances and robustness. The concept of a profile of the battery relative to a physical parameter of the battery units should be understood to mean a quantity of values for said parameter for the individual battery units at a particular time point. Operation of the battery is therefore not carried out on the basis of an isolated single observation of each individual battery unit, but on the basis of an overall picture of the battery made up of a large number of measurement values from many different battery units and which is also put in relation to the operational framework conditions of the battery that are recorded with the aid of the reference variable. Operational framework conditions of the battery are, for example, the ambient temperature of the battery, mechanical influences, such as vibration or jolts, the orientation of the battery, high or low current load on the battery due to discharging or the charging state of the battery or individual battery cells. Apart from the operational framework conditions, interactions between the individual battery units (e.g. mutual heating) and the installation site within the battery (e.g. in the center or at the edge) can also be taken into account. By this means, the operation of a battery having a plurality of banks and cells and associated therewith a relatively large spatial extent can be optimized and, at the same time, the operational reliability and availability of the battery can be increased. The derivation of the anticipated profile from the measurement value of the reference variable can be undertaken either based 5 on profiles previously determined (for example, by calculation and/or experiment) and stored, said profiles each being allocated to different measurement values of the reference variable, or based on an actual calculation which can be made, for example, with the aid of a neural network. Preferably, the cooling of the battery and/or the charging of the battery units is controlled and/or regulated depending on the deviation from the anticipated profile that is determined and the actual profile is thus specifically steered toward the anticipated profile. In the event of an inadmissible deviation from the anticipated profile, the battery can be at least partially switched off. A particularly high degree of accuracy can be achieved in the method in that at least one separate Bragg grating sensor is allocated to each battery unit. Particularly accurate evaluation is possible, even given a small cabling effort, in that allocated to each bank is a separate light waveguide, in which the Bragg grating sensors of all the battery units of the bank are arranged. In the event that the banks each have an equal number of battery units connected in series, a common light waveguide in which the Bragg grating sensors of said battery units are arranged can also be allocated to the battery units respectively arranged in the same position in the series connections. The Bragg grating sensor can be arranged within the battery unit, on the surface thereof or in the immediate vicinity thereof.

6 Preferably, the at least one reference variable is also measured with at least one Bragg grating sensor, said sensor preferably being arranged outside the battery. The reference variable can thus be measured without being influenced by the battery and therefore the anticipated profile can be determined with high accuracy. A simultaneous measurement of the temperature, the expansion and any vibrations of a battery unit is possible in that a recess is introduced into a surface of the battery units, said recess having a width and depth that are adapted to the diameter of the light waveguide, and that a light waveguide having at least one Bragg grating sensor is arranged in the recess. By this means, abnormal deformations of the battery unit that indicate an overload or a defect can be particularly advantageously identified. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an internal DC power supply system known from the prior art and comprising a high performance battery, FIG. 2 is the electrical arrangement of a battery module of FIG. 1, FIG. 3 is an example of a battery cell, FIG. 4 is a side view of a battery module, FIG. 5 is a front view of a battery module, FIG. 6 is a battery cell with a recess, FIG. 7 is the battery cell of FIG. 6 with a winding of a light waveguide, FIG. 8 is a first arrangement of Bragg grating sensors in light waveguide, FIG. 9 is a second arrangement of Bragg grating sensors in light waveguide, FIG. 10 is a first device for carrying out the method according to the invention, FIG. 11 is a second device for carrying out the method according to the invention, FIG. 12 is an actual battery profile, FIG. 13 is an anticipated battery profile. DETAILED DESCRIPTION A particularly suitable device for carrying out the method comprises - at least one Bragg grating sensor for measuring a value of at least one reference variable of the battery, - for each of the battery units, at least one respective Bragg grating sensor for measuring an actual value of the physical parameter of the battery units, 7938069_1 7 - a control and/or regulating device which is configured such that said device a) derives from the measurement value of the reference variable an anticipated profile of the battery relative to the physical parameter of the battery units, b) derives from the measured actual values of the physical parameter of the battery units an actual profile of the battery relative to the physical parameter, c)compares the actual profile with the anticipated profile and d)controls and/or regulates the operation of the battery depending on a determined deviation from the anticipated profile. The invention and further advantageous embodiments of the invention will now be described in greater detail according to features of the subclaims on the basis of exemplary embodiments shown in the drawings, in which: FIG. 1 shows a representation of the principle of an independent DC power supply system configured as a submarine 7938069_1 8 DC network 1 comprising a first partial network 2 and a second partial network 3 (not shown in detail), which is configured symmetrically to the first partial network 2. The partial networks 2, 3 are connectable or connected to one another via a network interconnection 4. Each of the partial networks 2, 3 has a generator 5 for generating electrical energy, a battery 6 for storing the electrical energy and, as an energy consumer, a motor 7 (e.g. a DC motor or a DC-fed motor) for driving a propeller 8 of the submarine and an on-board electrical system. The partial networks 2, 3 can naturally also comprise a plurality of generators 5 and batteries 6 connected in parallel. The batteries of the partial networks 2, 3 can also be partial batteries of a single battery. The individual components of the partial networks 2, 3 are connected to one another via protective and switching elements (not shown in detail). The following description relates to the partial network 2, but applies equally to the partial network 3. The battery 6 of the partial network 2 comprises a plurality of parallel-connected banks 10 (e.g. ten or more banks) of battery modules 11 connected in series. Each of the battery modules 11 in turn comprises - as shown in FIG 2 - a plurality of battery cells 12 connected in series (e.g. 20 battery cells connected in series). The battery cells 12 are high performance energy stores, for example, Li-ion battery cells, Li-polymer battery cells or combinations thereof. The individual banks 10 each have the same number of identical modules 11, each having the same number of battery cells 12. The size of the voltage of the network 1 is therefore determined by the number of battery cells 12 connected in series in the individual banks 10 and the size of the voltage 9 of the individual battery cells 12. The power available to the energy consumer in the network 1 is given by the number of banks connected in parallel. As FIG 3 shows, the battery cells 12 are configured, for example, cylindrical with a shell surface 13 and two end faces 14, 15. Situated at each of the end faces 14, 15 is a terminal contact 16 for the electrical connection to the battery cell 12. An exemplary design of a module 11 having six battery cells 12 is shown in FIGS. 4 and 5. FIG 4 shows a side view and FIG 5 a front view of a module 11. The battery module 11 comprises a mounting structure or housing 17 in which the battery cells 12 of the module 11 are held stacked on one another and connected in series with one another via electrical conductors 18. The electrical conductors 18 extend alternately on one side and the other side of the module 11. In addition, the module 11 comprises a module management device 19 for monitoring and controlling charging of the module 11. As FIG 6 shows, the cell 12 has a peripherally extending recess 21 at the surface thereof in the region of the shell surface 13, the width and depth of said recess being adapted to the diameter of a light waveguide. As shown in FIG 7, a light waveguide 22 in the form of a flexible glass fiber with a Bragg grating 20 is arranged in form-fitting manner in the recess 21. The light waveguide 22 extends in the recess exactly once round the shell surface 13 of the cell, i.e. said waveguide forms a single winding round the shell surface 13 of the cell. In principle, given a recess of appropriate size, the light waveguide 22 can also be wound multiple times round the cell 12. It is also possible for the Bragg grating sensor 20 to be arranged within the cell 12 or in the immediate 10 vicinity thereof. A plurality of Bragg grating sensors 20 can also be arranged within the winding round the cell 12. A Bragg grating sensor is formed by inscribing a grid structure in a light waveguide. A light waveguide 22 usually has a coating and a core. The Bragg grating 20 comprises a periodic sequence of disk-shaped regions arranged in the core of the light waveguide 22 and having a refractive index ni which is different from the normal refractive index n 2 of the core of the light waveguide. A mechanical deformation of the light waveguide 22 in the region of a Bragg grating 20, for example, due to a temperature change or a deformation of the cell, leads to a local longitudinal expansion or contraction and therefore to a change in the grating period, which results in a shift in the spectral intensity distribution of the backscattered light. The extent of this shift is a measure of the length change and thus of the temperature change or deformation of the cell 12. The measured physical parameter is therefore, for example, the temperature, expansion or vibration of the battery module or the battery cell. As FIG 8 shows, the Bragg grating sensors 20 of all the cells 12 of the battery modules 11 of a bank 10 can be arranged in a single common light waveguide 22 which extends along the cells 12 connected in series and forms one or more windings round each cell 12. If the banks 10 each have the same number of modules 11 connected in series, each with a similar number of cells 12 connected in series then, as FIG 9 shows, the Bragg grating sensors 20 of the battery cells 12 arranged at the same 11 respective position in the series connections can also be arranged in a single common light waveguide 22. The grating periods of the Bragg gratings 20 of the different cells 12 of a bank 10 can be selected to be the same or different. If the period of the Bragg gratings 20 of the different cells 12 of a bank 10 is selected to be different, then in order to measure the physical parameter, preferably light from a light source with a broadband distribution of the intensity over the wavelength range is shone into the light waveguide 22. Consequently a small portion of the light is backscattered at the Bragg gratings 20, specifically with a spectral intensity distribution that is characteristic of the respective grating, depending on the period of the grating. Different gratings and thus different battery units can therefore be identified based on different wavelengths of the backscattered light. The wavelength of the backscattered light is greater the larger the grating period is. If, however, Bragg gratings 20 having the same or essentially similar grating periods are utilized in a light waveguide 22, a pulsed monochromatic light source is preferably used for measuring the physical parameter. Different gratings and thus different battery units can therefore be identified by different transit times of the light pulses. FIG 10 shows in a schematic representation, for the case of the arrangement of the Bragg grating sensors 20 of FIG 8, a first embodiment of a device 30 for monitoring and controlling and/or regulating the operation of the battery 6 of FIG 1, wherein for simplification of the representation, only the first and last banks 10 and thereof only the respective first 12 and last battery modules 11 are shown. Apart from the battery modules 11, the battery 6 also has a battery housing 29. For each of the banks 10 of the battery 6, the device 30 comprises a light waveguide 22 with Bragg gratings 20. An additional light waveguide 22A with a plurality of Bragg gratings 20A is fed along the outside of the housing 29 of the battery and is fastened thereto. In addition to the light waveguides 22, 22A with the Bragg gratings 20, 20A, the device 30 also comprises a measuring arrangement 31 with, respectively, a broadband light source 32, a directional optical coupler 33 and a signal processing device 34 for each of the light waveguides 22, as well as a control unit 35 connected to the signal processing devices 34 of all the light waveguides 22. Each of the light waveguides 22 with the Bragg sensors 20 thereof is thus connected via a directional optical coupler 33 to a light source 32 and a signal processing device 34 allocated thereto. The directional coupler 33 couples light emitted by the light source 32 into the light waveguide 22 and out-couples this backscattered light from said light waveguide 22 to the signal processing device 34. The signal processing device 34 comprises a spectral analyzer for determining the spectral distribution of the light backscattered from the individual Bragg gratings 20, and a computer device which determines the extent of the respective shift relative to a reference position and converts said shift into a change in the physical parameter, for example, a temperature change, relative to a reference value for said 13 parameter at which the spectral distribution has the reference position. This is carried cut for each individual Bragg grating 20, 20A so that by this means the distribution of the physical parameter, for example, the temperature along the entire light waveguide 22, 22A at the sites provided with Bragg gratings 20, 20A is obtained. On use of Bragg gratings with the same or substantially the same grating period, the signal processing device 34 also has an evaluating electronic unit which detects and evaluates the transit time of the backscattered light having an altered spectral intensity distribution. In order to achieve a time resolved measurement, conventional OTDR (optical time domain reflectometry) technology can be used, as used in communications technology for assessing the quality of signal lines. It follows from the described functioning of the monitoring device according to the invention that the spatial distribution of the measured physical parameter, for example, the temperature along the light waveguide 22, 22A is detected. The measurement values are transferred by the signal processing devices 34 to the control device 35, in which an actual profile 40 of the battery 2 in relation to the physical parameters is created from the measurement values, as shown by way of example in FIG 12 for a battery having twelve banks 10 each having twelve battery cells 12. The columns 41 of the profile 40 correspond to the banks 10, wherein the individual boxes 42 in a column represent the individual cells 12 of the bank 10. In addition, with the aid of the light waveguide 22A fastened to the housing 29, a reference variable, for example, the ambient temperature or vibrations of the housing are measured 14 and therefrom, an anticipated profile 45 of the battery 6 is derived by the control device 35, as shown by way of example in FIG 13. The derivation of the anticipated profile 45 from the measurement value of the reference variable can be undertaken either on the basis of profiles previously determined (e.g. by calculation and/or experiment) and stored in the control device 35, said profiles each being allocated to different measurement values of the reference variable, or based on an actual calculation which can be made, for example, with the aid of a neural network. The actual profile 40 is compared in the control device 35 with the anticipated profile 45 and, by means of the control device 35, the operation of the battery is controlled and/or regulated depending on a deviation from the anticipated profile 45. In the event that the profiles 40, 45 shown in FIGS. 12 and 13 represent, for example, the temperature of the cells, it is clear from the profile 45 that the maximum of temperature is to be expected in the center of the battery. In fact, however, in the actual profile 40 there is an additional maximum in the lower right region 43 of the battery, which indicates insufficient cooling or the beginning of a fault in the cells 12 in this region 43. In a first step, the control device 35 can now activate, via a control line 39, an additional cooling device 37 for the battery 6. Alternatively and/or in addition, the control device 35 can signal the relatively abnormal operating status via communications connections 38 to the module management devices 19 of the affected battery modules 11, so that the module management devices 19 can instigate targeted countermeasures. If, however, the comparison of the actual profile 40 with the anticipated profile 45 reveals an inadmissible deviation from the anticipated profile 45, the battery is at least partially 15 switched off by the control device 35 (e.g. by opening a battery switch). A second embodiment of a device 30 shown in FIG 11 differs from the device 30 shown in FIG 10 in that the measuring arrangement 31 comprises a common light source 32 for all the light waveguides 22 and a common signal processing device 34 in place of a respective separate light source 32 and signal processing device 34 for each of the light waveguides 22. The directional couplers 33 are connected in series with one another via light waveguides 36A, 36B and couple light emitted by the light source 32 into the light waveguide 22 and out couple backscattered light from said waveguides 36A, 36B to the signal processing device 34. The directional couplers 33 are configured so as only to out-couple light of a particular wavelength range (referred to below as the "out-coupling region") and to allow through light outside said wavelength range. The directional couplers 33 have different out-coupling regions. Each of the light waveguides 22 or banks 10 is precisely allocated to one of said out-coupling regions. Therefore a directional coupler 33 only out-couples light from the wavelength range allocated to the light waveguide 22 attached thereto and light in out-coupling regions of the other light waveguides 22 is allowed to pass. Only one of the directional couplers 33 is directly connected to the common light source 32 and the common signal processing device 34. An arrangement of this type is achievable with a minimum of expenditure on components for light sources and signal processing devices. The number of battery banks 10 that can be monitored thereby is essentially only limited by the bandwidth that must be provided per Bragg grating for spectral separation of the signals backscattered by the individual 16 Bragg gratings, by the required width of the out-coupling regions and the bandwidth of the light source.

Claims

1. A method for operating a high-performance battery comprising a plurality of parallel connected banks of battery units connected in series, the method comprising: measuring actual values of a physical parameter of the battery units with the aid of Bragg grating sensors and deriving an actual profile of the battery relative to the physical parameter from the measured actual values, measuring at least one reference variable of the battery and deriving an anticipated profile of the battery relative to the physical parameter of the battery units from the measured at least one reference variable based on profiles previously determined by calculation and/or experiment and stored in a control device of the battery, said profiles each being allocated to different measurement values of the at least one reference variable, comparing the actual profile with the anticipated profile, and controlling and/or regulating the operation of the battery depending on any deviation of the actual profile from the anticipated profile.

2. The method as claimed in claim 1, wherein cooling of the battery and/or charging of the battery units is controlled and/or regulated depending on the deviation from the anticipated profile.

3. The method as claimed in claim 1 or 2, wherein in the event of an inadmissible deviation from the anticipated profile, the battery is at least partially switched off.

4. The method as claimed in any one of the preceding claims, wherein an ambient temperature or vibration of a housing of the battery is measured as a reference variable.

5. The method as claimed in any one of the preceding claims, wherein the at least one reference variable is measured with at least one Bragg grating sensor, said sensor preferably being arranged outside the battery.

6. The method as claimed in any one of the preceding claims, wherein the physical parameter is a temperature, expansion or vibration of the battery unit.

7. A device for carrying out the method as claimed in any one of the preceding claims, said device comprising: 7938032_1 18 at least one Bragg grating sensor for measuring a value of at least one reference variable of the battery, for each of the battery units, at least one respective Bragg grating sensor for measuring an actual value of a physical parameter of the battery unit, a control and/or regulating device configured such that said device a) derives from the measurement value of the reference variable an anticipated profile of the battery relative to a physical parameter of the battery units, b) derives from the measured actual values of the physical parameter of the battery units an actual profile of the battery relative to the physical parameter, c) compares the actual profile with the anticipated profile and d) controls and/or regulates the operation of the battery depending on a deviation of the actual profile from the anticipated profile.

8. The method as claimed in claim 7, wherein each bank is allocated a separate light waveguide, the Bragg grating sensors of all the battery units of the bank arranged in the separate light waveguide.

9. The method as claimed in claim 7 or 8, wherein the banks each have an equal number of battery units connected in series, wherein a common light waveguide in which the Bragg grating sensors of the battery units are arranged is allocated to said battery units respectively arranged in the same position in the series connections.

10. The method as claimed in one of claims 7 to 9, wherein a recess is introduced into a surface of the battery units, said recess having a width and depth adapted to a diameter of a light waveguide, and a light waveguide having at least one Bragg grating sensor is arranged in the recess.

11. The device as claimed in any one of claims 7 to 10, wherein the battery units are battery cells or battery modules composed of a plurality of battery cells connected in series. Siemens Aktiengesellschaft Patent Attorneys for the Applicant SPRUSON & FERGUSON 7938032_1