Electrical energy supply device with a nominal rated capacity and method for providing a nominal rated capacity in an electrical energy supply device

Abstract

Electrical energy supply device (10) with a respective nominal capacity of at least one predetermined electrical characteristic, wherein the respective nominal capacity is provided by means of a plurality of user units (12), each of which has a respective individual capacity relating to the respective characteristic, and wherein a control device (19) is designed to control an energy exchange (E) between the energy supply device (10) and at least one device-external device (100), wherein the sum of the respective individual capacitances of the user units (12) is greater than the respective nominal capacity of the at least one characteristic value, and the control device (19) is configured to limit the respective characteristic value to the respective nominal capacity during the energy exchange (E), and wherein some of the user units (12) in a respective branch (11) are connected to a series circuit (13), and each branch (11) is connected to a busbar arrangement (18) of the energy supply device (10) via at least one galvanically isolable switching unit (15), and within each branch (11) a bridging circuit (N11) is provided for each user unit (12), and the energy supply device (10) carries out the energy exchange (E) via the busbar arrangement (18), and the control device (19) is configured toto control the at least one switching unit (15) and the bridging circuits (N11) of each strand (11) to limit the at least one characteristic variable, characterized in that each strand (11) is connected to the busbar arrangement (18) via a DC-DC converter (14) and the control device (19) is designed to control the DC-DC converters (14) to limit the at least one characteristic variable, wherein the control device (19) is designed to determine a respective wear value for each user unit (12) and to deactivate one of the user units (12) whose wear value meets a predetermined wear criterion by electrically disconnecting it, and to put at least one use unit (12) that has been taken out of service back into operation by electrically coupling it if its wear value meets a predetermined similarity criterion in comparison with the respective wear value of the use units (12) that are already in operation, by waiting until all other use units have a similar degree of wear.

Description

[0001] The invention relates to an electrical energy supply device in which a plurality of utilization units are provided. The energy supply device can be, for example, a stationary electrical storage device or a vehicle battery for an electric vehicle, in which case battery modules can be provided as utilization units. The energy supply device has a nominal rated capacity, which is provided externally for at least one connected device. The invention also includes a method for providing the nominal rated capacity using the electrical energy supply device.

[0002] An energy supply device can, for example, be provided for a charging station for charging electrically powered motor vehicles. However, an energy supply device can also be designed, for example, as a traction battery for an electrically powered motor vehicle, i.e., as a mobile energy storage device.

[0003] An energy supply device with multiple power units for storing electrical energy is known, for example, from US 2006 / 0 092 583 A1. The energy supply device described therein can optionally connect the power units in parallel between two busbars or connect them in series between the busbars to add up the electrical voltages of the power units.

[0004] For an energy supply device, a nominal value or nominal capacity, e.g., 1 kWh, can be specified for a specific parameter, such as energy storage capacity. The goal of an energy supply device is to ensure that it can operate reliably and at its nominal capacity for as many operating hours as possible. However, using particularly robust load units for this purpose makes an energy supply device expensive to manufacture. Another alternative is to operate the load units as gently as possible, but this, in turn, limits the performance of an energy supply device.

[0005] DE 10 2015 216 097 A1 discloses a submarine that has several separate, self-sufficient DC voltage networks. Each DC voltage network can be provided with its own string of battery modules, each of which can be connected to its DC voltage network via a DC / DC converter.

[0006] DE 10 2011 054 145 A1 discloses a fault-tolerant battery architecture comprising multiple strings of battery modules, each of which can be electrically bridged within its string if it is defective. The strings are connected in parallel, with their electrical power flow being regulated by a connection element.

[0007] EP 3 038 229 A1 discloses a battery-based energy storage device in which battery modules are connected in series to form a plurality of battery strings, the battery strings being connected in parallel to one another and each battery string being connected to a common busbar via a DC / DC converter.

[0008] From WO 2013 / 021 364 A1, a system for generating, storing and providing electrical energy is known, which comprises battery strings connected in parallel, which have a DC-DC converter at one end of the string, via which the battery strings are coupled to a switching matrix.

[0009] DE 10 2014 220 062 A1 describes a circuit of several battery cells, which are electrically coupled to the battery or electrically decoupled from the battery depending on a quality factor that depends on the battery cell.

[0010] DE 10 2013 013 673 A1 relates to a circuit for controlling the state of charge of a battery by connecting each battery cell to a control circuit.

[0011] DE 10 2012 203 585 A1 describes a battery unit consisting of at least two batteries for which different operating modes are provided, whereby different battery replacement concepts are supported and a failure of an individual battery does not lead to a failure of the entire battery unit.

[0012] DE 100 10 985 A1 relates to a method in which the fuel cells of a fuel cell system can be connected in series or parallel and can be switched on or off by bridging.

[0013] DE 11 2015 003 701 T5 relates to a generator system in which a part of the electrical load of at least one generator unit is gradually transferred to at least one other generator unit if the operating loads are unbalanced.

[0014] DE 10 2013 106 265 A1 describes a method relating to an energy storage device consisting of multiple storage units. The method involves coupling these storage units to a current path or short-circuiting the current path in this section depending on determined characteristic and / or state variables.

[0015] US 2009 / 0 066 291 A1 relates to an energy storage device in which individual storage units are connected in series, the series then being connected in parallel, whereby it can be decided in each case whether an individual storage unit is to be bridged or connected.

[0016] DE 20 2014 004 749 U1 relates to an electrical circuit via which at least one electrical energy storage device can be electrically connected to at least one other electrical energy storage device of another module.

[0017] The invention is based on the object of providing a cost-effective yet reliable energy supply device.

[0018] The problem is solved by the subject matter of the independent patent claims. Advantageous developments of the invention are described by the dependent patent claims, the following description, and the figures.

[0019] The invention provides an electrical energy supply device that provides a respective nominal value or a respective nominal nominal capacity with respect to at least one predetermined characteristic, for example the storage capacity and / or the rated electrical power. Rated capacity here therefore refers to the value that can be provided during normal operation or without time restrictions or damage when a device external to the device is connected to the energy supply device and operated with it. The respective nominal capacity with respect to the at least one electrical characteristic (for example the storage capacity and / or the electrical power) is provided by means of a plurality of usable units.Such a utility unit can, for example, contain at least one battery cell or a battery cell module with multiple battery cells, or a capacitor or a capacitor arrangement with multiple capacitors, or solar cells or fuel cells. Each utility unit naturally has an individual capacity related to the respective characteristic, for example, an individual storage capacity and / or an individual rated power.

[0020] A control device of the energy supply device is configured to control an energy exchange between the energy supply and at least one device external to the device that can be connected to the energy supply device. Energy exchange refers, on the one hand, to the energy output to the device and, on the other hand, to the energy input from the device.

[0021] In order to make the energy supply device more reliable and longer-lasting, the invention provides that the sum of the said respective individual capacities in the user units is greater than the respective nominal capacity of the energy supply device. In other words, the user units, for example, have a greater storage capacity in total than is indicated externally by the nominal capacity of the energy supply device. Additionally or alternatively, the sum of the individual rated powers of the user units can be greater than the externally indicated nominal power of the energy supply device as a whole. The control device is accordingly configured to limit the at least one characteristic variable to the respective nominal nominal capacity during the said energy exchange. In other words, although the at least one characteristic variable (e.g.

[0022] Storage capacity and / or power) the sum of the individual capacities is greater than the respective nominal capacity, but the control device limits the operation of the energy supply device in such a way that it only provides the respective nominal capacity to the outside, i.e. to the at least one device.

[0023] The invention has the advantage that each utility unit can be operated below its individual nominal capacity, meaning that the load or wear on each utility unit can be lower than it would be if each utility unit were operated at its individual capacity. This reduces the probability of a utility unit failing due to wear. Overall, this results in the utility units being operated more gently than if they were operated at their individual capacity. This extends their service life. A further advantage is that if one utility unit fails, the energy supply device as a whole can still provide the nominal capacity, meaning that the failure of one utility unit does not result in the nominal capacity of the energy supply device being reduced.The energy supply device can therefore continue to operate without restrictions even if one or more user units fail.

[0024] The energy supply device has the following structure. Several of the service units are connected in a respective circuit branch or strand to form a series circuit. Each strand is connected to a busbar arrangement of the energy supply device via a DC / DC converter and at least one galvanically isolating switching unit. A galvanically isolating switching unit is a mechanical switching unit, for example a contactor or an arrangement comprising several contactors. In general, the DC / DC converter can be a boost converter, a buck converter, or an inverting converter. A buck converter is preferably used as the DC / DC converter. Within each strand, each service unit can also be individually switched. For this purpose, a bridging circuit is provided for each service unit within each strand.By means of the bridging circuit, a useful unit can be electrically bridged within the series connection of the string so that it no longer contributes to the string current of the series connection and also no longer contributes to the string voltage.

[0025] The control device can be configured to determine the respective wear value of each user unit and to decommission those user units whose wear value meets a predetermined wear criterion by electrically disconnecting them. In other words, these user units are excluded from the energy exchange. If the degree of wear meets the wear criterion, a user unit is switched off. In the context of managing digital memory cells, this is known as bad-block management. This approach is transferred to electrical user units by the invention. The advantage of such bad-block management is that when operating the energy supply device, the weakest, i.e., the most worn, user units do not have to be taken into account, for example in the form of load balancing, because these user units are decommissioned.

[0026] Preferably, however, the control device is configured to later recommission at least one of the decommissioned utility units by electrically connecting it, so that it is once again involved in the energy exchange. This occurs if the wear value of the utility unit meets a predetermined similarity criterion compared to the respective wear value of the utility units still in operation. In other words, the control device waits until all other utility units are also worn to such an extent that the utility units again exhibit a similar degree of wear. This means that the utility units once again exhibit similar electrical properties (within the meaning of the similarity criterion), so that joint operation is possible again, i.e., load balancing, for example, does not lead to an excessive restriction of operation of the utility unit with the lowest wear value.The similarity criterion can, for example, state that a maximum difference with respect to at least one parameter must lie within a range of 10 percent to 100 percent. An underlying parameter can, for example, be the impedance of the wear unit. In other words, the similarity criterion for the wear values ​​can specify that their difference must lie within a range of 10 percent to 100 percent. For example, an average of all wear values ​​can be calculated and the difference from this average can then be calculated. For example, the maximum and minimum wear values ​​can also be specified or determined, and the difference then relates to the maximum and minimum wear values.

[0027] The invention also includes further developments which result in additional advantages.

[0028] The at least one parameter that is limited to the respective nominal capacity can be the electrical storage capacity of the energy supply device and / or the maximum electrical power and / or the maximum electrical current. By limiting these parameters, gentle operation of the utility units can be achieved.

[0029] Each utility unit can comprise at least one battery cell or one battery cell module or a combination of several battery cell modules and / or at least one fuel cell and / or at least one solar panel and / or at least one capacitor. A utility unit can also comprise a generator.

[0030] For a specific energy exchange process, the question arises as to how the user units are connected to the at least one connected device. The control device can be configured to electrically connect more user units to the at least one control device for the energy exchange process than is necessary to provide the respective nominal capacity of the at least one characteristic. This allows each user unit to be operated in the manner described with a lower load than its individual capacity.

[0031] A further development provides that the control device is configured to operate the energy supply device for a predetermined period of time at its gross capacity, which represents the sum of the individual capacities. This allows a so-called boost mode or turbo mode to be implemented. The period of time can range from 1 s to 1 min.

[0032] The control device can be configured not to use all of the user units in a plurality of consecutively performed energy exchange processes, but rather to electrically couple only some of the user units to the at least one connected device. Rotation can then take place. In other words, in this case the control device is configured to select the user units to be connected for each of the energy exchange processes according to a predetermined exchange rule. One possible exchange rule can be achieved using the "Round Robin" algorithm. Additionally or alternatively, the exchange rule can, for example, select those user units that exhibit the least wear for a given energy exchange process. Wear or tear in a user unit can be quantified, for example, by its electrical impedance.The higher the impedance of a wear unit, the more advanced its wear or deterioration. In general, wear can be expressed as a so-called SoH (State of Health), as is known from the state of the art. Another wear value dependent on wear can also be defined and determined, for example, through simple tests. The replacement rule results in even wear across the wear units, thus reducing the likelihood of a single wear unit failing sporadically.

[0033] The control device can be configured to determine the respective wear value of each user unit and to decommission those user units whose wear value meets a predetermined wear criterion by electrically disconnecting them. In other words, these user units are excluded from the energy exchange. If the degree of wear meets the wear criterion, a user unit is switched off. In the context of managing digital memory cells, this is known as bad-block management. This approach is transferred to electrical user units by the invention. The advantage of such bad-block management is that when operating the energy supply device, the weakest, i.e., the most worn, user units do not have to be taken into account, for example in the form of load balancing, because these user units are decommissioned.

[0034] A user unit can also fail completely, i.e., break. In such a case, the control device can be configured to detect a defective user unit and electrically disconnect it from the other user units. The detection of a defective user unit can be carried out using means from the prior art. For example, an electrical current generated by the user unit can be checked for a defect criterion. For example, a defect criterion can be specified that a charging current of the user unit is less than a predetermined threshold value. However, if a user unit is electrically isolated or disconnected, it can be replaced during operation of the energy supply device. Accordingly, in this development, the control device is configured to electrically couple this user unit to the other user units during operation of the energy supply device after the defective user unit has been replaced with a new one.This makes it possible to replace a defective unit while the energy supply device is in operation, so that the energy supply device cannot be taken out of operation for the replacement, but can carry out an energy exchange continuously.

[0035] The energy supply device carries out the energy exchange via said busbar arrangement. In other words, at least one branch is electrically connected to busbars of the busbar arrangement by means of its galvanically isolable switching units or by means of its individual switching unit, so that an electrical current can flow from the at least one branch via the busbar arrangement to the at least one device, thereby effecting the energy exchange. The control device is configured to control the DC-DC converters and the at least one switching unit and the bridging circuits of each branch to limit the at least one characteristic variable (e.g., the storage capacity and / or the electrical power).

[0036] The invention also includes a method for providing a respective nominal capacity of at least one predetermined electrical characteristic in an electrical energy supply device. The respective nominal capacity of the at least one electrical characteristic is provided by means of a plurality of user units, each of which has an individual nominal capacity relating to the respective characteristic. The control device controls the energy exchange between the energy supply device and the at least one device external to the device, limiting the at least one characteristic to the respective nominal capacity during the energy exchange. Overall, however, the user units, with the sum of their respective individual capacities, provide a gross capacity that is greater than the nominal capacity of the at least one characteristic.This results in the described advantageous effects regarding the improvement of the longevity of the energy supply device. Of course, the energy supply device can be operated at its gross capacity for a predetermined period of time. This period can range from 1 second to 1 minute. In other words, so-called boot operation can be provided.

[0037] The sum of the individual nominal capacities thus represents the gross capacity of the energy supply device. The nominal capacity represents the net capacity, as it can be used or tapped externally from the perspective of at least one device. This results in excess capacity in the energy supply device.

[0038] The invention also includes further developments of the method according to the invention that have features already described in connection with the further developments of the energy supply device according to the invention. For this reason, the corresponding further developments of the method according to the invention are not described again here.

[0039] An exemplary embodiment of the invention is described below. It shows: Fig. 1 is a schematic representation of an embodiment of the energy supply device according to the invention; Fig. 2 a schematic representation of a useful unit of the energy supply device of Fig. 1 with a bridging circuit.

[0040] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual, independently considered features of the invention, which also further develop the invention independently of one another and are thus also to be considered as components of the invention, either individually or in a combination other than that shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0041] In the figures, functionally identical elements are provided with the same reference numerals.

[0042] Fig. 1 shows an electrical energy supply device 10, which can be designed as an energy storage device or as a pure energy source, or as a combination thereof. The energy supply device 10 can, for example, be provided as a stationary storage device for electrical energy. It can, for example, be installed on a road network. At least one device 100, for example an electrically driven motor vehicle, can then be connected to the energy supply device 10 in order to charge, for example, a traction battery of the motor vehicle by means of an energy exchange E. The energy supply device 10 can also be intended for use as a mobile battery or traction battery or solar storage device. As a traction battery, for example, an electric machine of a traction drive can be connected to the energy supply device. In the charged state, the energy supply device 10 can output at least 1 kW of electrical power and / or supply at least 1 kWh of electrical energy.

[0043] In the energy supply device 10, several circuit branches or strings or branches 11 can be provided for the energy exchange E, wherein in each branch 11, several of the user units 12 can be connected to form a series circuit 13. The user units 12 are thus combined in the energy supply device 10, for example, in a vehicle traction battery or in a stationary electrical storage device. The energy supply device 10 can have a housing in which the branches 11 and the busbar arrangement 18 are arranged.

[0044] Each user unit 12 can contain an electrical energy storage device and / or a pure source of electrical energy. As an energy storage device, a user unit can contain, for example, an electrochemical battery cell or a battery cell module with multiple battery cells or a capacitor or a capacitor arrangement with multiple capacitors. Examples of battery cells are those using lithium-ion, lead, or solid-state technology. Examples of suitable capacitors are double-layer capacitors (so-called supercaps (R)) with a capacitance of preferably at least 1 mF, in particular at least 100 mF). Examples of a pure source are a fuel cell and a solar cell. As an energy source, a user unit 12 can contain, for example, a fuel cell or a fuel cell stack or a solar cell or a solar panel or a generator, e.g. of a power plant (e.g. a pumped storage power plant).A utility unit 12 can also have a parallel connection of, for example, several battery cells or battery cell modules to increase the current.

[0045] Within each string 11, the technology used by the useful units 12 is uniform, i.e., for example, only battery modules or only solar cells are provided. Each string 11 therefore has useful units 12 of the same technology, for example, as a battery cell module, each one has a lithium-ion accumulator. However, mixed technologies can be provided by different strings 11. This allows the energy supply device to be adapted to a specific application or to a required operating profile. For example, for the use of the energy supply device 10 in a motor vehicle as a traction battery, two strings of different technologies can be provided, e.g., with a distribution of the number of useful units 12: 80% energy cells (high storage capacity), 20% power cells (more expensive, but greater power flow).

[0046] Per strand 11 can, as in Fig. 1, in addition to the series circuit 13 of utility units 12, the following may also be provided: a DC-DC converter 14, a mechanical switching unit 15 at each of the string ends 11', a measuring device 16 for a string current I and / or a voltage measuring device for detecting a total voltage or string voltage U of the string 11.

[0047] Each DC-DC converter 14 can be designed in a manner known per se. In general, the DC-DC converter can be a boost converter, a buck converter, or an inverse converter. Each DC-DC converter 14 can, in particular, be a buck converter. Each switching unit 15 can be designed to be mechanically switched and, in particular, is galvanically isolable. Each switching unit 15 can have several ON / OFF contactors or (as in Fig. 1) have a contactor designed as a changeover switch (1-to-N multiplexer). By means of each switching unit 15, the respective strand end 11' can be alternately galvanically connected and disconnected from strand connections 17. Each strand connection 17 represents an electrical connection to a busbar 18'. The busbars 18' as a whole form a busbar arrangement 18 consisting of independent busbars 18'. Each strand connection 17 of a strand 11 can be connected to a different busbar 18' of the busbar arrangement 18. Thus, several strand connections 17 can be provided per strand end 11' (positive pole and negative pole) in order to alternately connect the strand 11 to several different busbars 18' of the busbar arrangement 18 or to galvanically disconnect it from each busbar 18'.By opening the two switching units 15 of a string 11, the latter can be galvanically decoupled and also replaced during ongoing operation of the energy supply device 10.

[0048] Each strand 11 can provide a total voltage or direct voltage U at the strand connections 17 by means of the series connection 13. The direct voltage U can be a direct voltage (HV) that can be more than 60V, in particular more than 100V. However, it can also be provided that the direct voltage U is in the range from 8V to 60V. A direct voltage is therefore present between two busbars 18' when a strand 11 is galvanically connected to them. For this purpose, each strand 11 can be alternately galvanically connected to a pair of busbars 18 by means of its switching units 15. The strand 11 can be alternately galvanically connected to a pair of busbars by means of the switching units 15 by connecting one rod end 11' to a busbar 18' of the busbar pair, so that the direct voltage U drops across the busbar pair.

[0049] The measuring unit 16 can also provide the said total voltage measurement across the string 11 in order to detect the DC voltage U. For this purpose, the measuring unit 16 is preferably connected downstream of the DC-DC converter 14, as shown in Fig. 1 to enable voltage regulation by means of the DC-DC converter 14. As described in connection with Fig. 2 will be explained later, an individual voltage measurement is also provided in each utility unit 12.

[0050] The at least one device 100 can be connected to the strands 11 via the busbar arrangement 18. The busbars 18' of the busbar arrangement 18 thus form a busbar matrix, via which at least one selected strand 11 can be electrically connected to a selected device 100, while simultaneously another device can be electrically connected to at least one other strand 11. The devices remain galvanically isolated from one another.

[0051] Which line 11 is electrically connected to which busbar 18' can be determined by a control device 19. For this purpose, the control device 19 can determine a respective energy requirement and / or a respective power requirement of the at least one connected device 100 and then select at least one line 11 by means of which the requirement can be met. The device 100 itself can communicate the requirement, e.g., via a communication interface, or it can be stored, e.g., as a fixed, predetermined value in the control device 19. The control device 19 can then connect the switching units 15 of each selected line 11 to the busbars 18' leading to the connected device 100.

[0052] An additional switching unit 15' can be provided between each two strands 11 to connect two strands 11 in series and thus add their strand voltages. This allows a higher voltage to be provided between two busbars 18' than can be generated by a single strand 11.

[0053] The busbars 18' can each be connected in pairs to an output terminal 20, to which a device 100 can be connected. The connections of the busbars 18' to the individual electrical contacts of the output terminals 20 are shown in Fig. 1 by corresponding labels 1+, 2+, 3+, 1-, 2-, 3-, where "+" can stand for positive potential and "-" for negative potential or ground potential. The designations symbolize three possible busbar pairs 1+, 1- and 2+, 2- and 3+, 3-, whereby the electrical contacts of the output terminals 20 can also be designed to be alternately connectable to different busbars 18' using a further switching device (not shown). The output terminals 20 can always remain galvanically isolated from one another, as long as each busbar 18' of a terminal 20 is galvanically connected to another branch 11.

[0054] Simultaneous charging and discharging of different strings 11 can also be provided in order, for example, to supply a device 100 one after the other with electrical energy from different strings 11, which are recharged in between. For example, a charging process of an electric vehicle (or a device in general) can take place via a pair of busbars with an output voltage of, for example, 400 V, while at the same time the charging of other strings 11 can take place, for example, via a transformer 21 at a charging voltage of, for example, 800 V from a supply network 22 or from another energy source external to the device. The transformer 21 can be connected to an input terminal 23 of the energy supply device 10. If the strings 11 are not designed for this charging voltage, they can be connected in series to form a series circuit using the switching unit 15'.The galvanic isolation is achieved by using different busbars 18' for the respective strings 11 and / or each voltage level (output voltage and charging voltage, e.g. 400V and 800V).

[0055] Power concentration can also be achieved by means of the strings 11 in that an energy source, e.g. a solar system, feeds energy into at least one string 11 at the input terminal 23 with a first power and the string 11 then outputs this energy to a device 100 connected to an output terminal 20 with a second power which is greater than the first power.

[0056] As a stationary storage device, the energy supply device 10 can optionally have a modular AC / DC converter arrangement 24 for the input connection 23 with a plurality of AC / DC converters 24', which can be individually switched between the busbars 18' by means of a switching unit 25 in order to be able to provide a predetermined current intensity and / or charging voltage for a charging current on a busbar 18' or to be able to galvanically isolate the respective AC / DC converters 24' from the busbar arrangement 18. Galvanic isolation from the input connection 23 is also possible by means of additional switching units 26. The switching units 25, 26 can each be formed by a contactor. The switching units 25, 26 can be controlled by the switching device 19. By opening the two switching units 25, 26 of an AC / DC converter 24', the converter can thus be galvanically decoupled and can also be replaced during ongoing operation of the energy supply device 10.The switching units 25, 26 thus represent decoupling switches. The AC / DC converters 24' can be designed with galvanic isolation. However, the AC / DC converter arrangement 24 does not necessarily have to have galvanic isolation. Other converters are more advantageous. Galvanic isolation can be ensured at any time using the mechanical switches of the lines.

[0057] A grid-independent energy source, such as an emergency power generator or a wind turbine, can be connected to the input connection 23 instead of the supply grid 22. Conversely, the energy supply device 10 itself can also act as a grid-forming device, i.e., it can specify a grid frequency for other devices connected to the input connection. This is particularly advantageous for the use of the energy supply device 10 in a region without its own supply grid 22. AC devices can be operated as if on a public supply grid without adaptation. The opposite of grid-forming operation is grid-following operation, i.e., synchronization to a predetermined grid frequency takes place.

[0058] To switch the switching units 15, 15', 25, 26 and the user units 12, as well as to receive data from the user units 12, the control device 19 can be coupled to these components via a communication device 27. The communication device 27 can comprise, for example, a communication bus, e.g., a CAN bus (CAN - Controller Area Network), or an Ethernet.

[0059] The control device 19 thus accumulates general knowledge about what can be switched and how, for example, which busbar 18' can be switched to which string 11. The control device 19 can be configured at least partially as a central control device for all strings 11 and / or at least partially as a distributed control device per string 11. It can have a processor device with at least one microcontroller and / or at least one microprocessor. An operating program of the processor device can be configured, when executed by the processor device, to carry out the described method steps for operating the energy supply device 10.

[0060] Optionally, capacitors 30, 31 (particularly double-layer capacitors) can be provided at the output terminals 20 and / or the input terminal 23 to buffer load peaks. The load units 12 can thus be operated more gently during load peaks (e.g., in the range of up to a duration of 3 or 5 seconds), since the load peak is dampened. A load peak can have an electrical power greater than the sum of the individual rated powers of the connected load units 12, in particular a power greater than 1.2 times the sum.

[0061] For a switching operation on the busbars 18', a charge transfer circuit or limiting circuit 32 (switch and resistance element) can be connected in series with the respective capacitor 30, 31 to conduct a capacitor current through the resistance element, thereby limiting the current intensity of the capacitor current to a predetermined maximum value. The limiting circuit 32 can be used for charging and discharging the respective capacitor 30, 31. A capacitor 30, 31 with its limiting circuit 32 represents a capacitor device. The limiting circuit 32 thus represents a precharging circuit.

[0062] Cooling of the strands 11 (in particular of the useful units 12 in the strands 11) can be provided, for example, in a shelf by arranging a cooling level below the strand level.

[0063] Each busbar 18' can be made of aluminum or copper. Aluminum is the less expensive material and lighter than copper. Due to its specific resistance, aluminum generates power loss (more so than copper), which can be used to generate heating power for temperature control of the service units 12 (especially battery cells). This heating power can be transferred from the busbars 18' to the service units 12 via a thermal coupling, e.g., a cooling circuit.

[0064] When current is distributed among multiple strings 11 on a busbar 18', the current I can be adjusted, e.g., equalized or dynamically shifted, by setting / regulating the individual string currents I via the DC-DC converter 14 of the string 11. For example, the required total current for the device 100 can be distributed among N strings 11, e.g., N=3, and each string 11 can generate a current I specifically set for it, e.g., with N=3: 50%, 25%, 25%.

[0065] This allows the technology available in the respective string 11 of the user units 12 to be taken into account so that the user units 12 are operated within their specifications. Since the electrical voltages U can be determined, the current I can then be set using the DC-DC converter 14 so that, for example, compensating currents flow between the strings 11 that are smaller than a threshold value. This can ensure, for example, that in the case of batteries, a current I of up to 300-400 A flows per battery cell only for 15 s, but a continuous current of only up to 150 A. Each string 11 can therefore be operated with its own operating strategy, adapted to its technology. A suitable current strength I can be set using the DC-DC converter 14.

[0066] Additionally or alternatively, depending on the cable length 28 of the busbar sections leading from a branch 11 to an output connection 20 (i.e. to a consumer), the current intensity I of the respective branch 11 can be adjusted by the control device 19 using its DC-DC converter 14 in order to adjust the distribution of the current intensities I in the case of several branches 11 connected in parallel as a function of the cable length 28 and as a function of the resulting losses, so that the losses can be optimized (e.g. minimized or maximized for heating) and / or distributed locally. A branch 11 with a shorter cable length 28 of the supply line via the busbars 18' can be assigned a larger current intensity I for the purpose of minimization than a branch 11 with a longer cable length 28. In this way, the effect of different cable lengths is compensated.The current I can also be adjusted depending on the current temperature of the cable sections. This type of power management can compensate for the disadvantage of aluminum's higher resistivity by specifying and adjusting the current on individual cable sections.

[0067] If necessary, the control device 19 can thus connect the strings 11 with the currently required property to the busbars 18 used, which lead to the output connection 20 from which the power is tapped by a connected device 100. Each string 11 can be coupled as needed using its switching units 15. Each string 11 can be discharged / charged individually. Additionally or alternatively, the efficiency of the DC-DC converter 14 within the string 11 can be optimized by adjusting its input voltage by selecting and connecting utility units 12. The DC-DC converter 14 of each string 11 can thus fulfill two tasks. It limits the string current I to a predeterminable setpoint so that utility units 12 can be operated according to their predefined specifications (operating limits).The voltage U of string 11 can be adjusted to the busbar voltage. This allows the compensating currents between multiple strings 11 to be reduced. In addition, the DC-DC converter 14 ensures that a specified target voltage is applied to the string terminals 17, regardless of the number of units 12 actively operating in string 11.

[0068] A current measurement 16 for the phase current I can be carried out centrally in the measuring unit 16 in the phase 11 in the manner described and is necessary anyway for the control of the DC-DC converter 14.

[0069] The central control unit can also individually reconfigure each line 11, i.e., connect and disconnect utility units 12 in the series circuit 13 of line 11. If, for example, the line voltage U is lower than the required rail voltage of the connected busbars 18', more utility units 12 can be connected in the series circuit 13 of line 11. This can be done so quickly using semiconductor switches (e.g., transistors) that it can be completed during a switching pause of the DC-DC converter 14.

[0070] In Fig.2 shows how each user unit 12 can be electrically bridged, electrically isolated and / or discharged by an individual switching device N10. Semiconductor switches T (transistors) are provided for this purpose. Each user unit 12 can provide the following functions: a bridging / bridging circuit N11, a diagnostic unit N12, a (particularly passive) load balancing / discharge circuit N13, and a decoupling / isolating circuit N14. A semiconductor switch T only needs to be able to block a low voltage, e.g., 2x individual voltage V of the user unit 12. The load balancing can also be carried out actively in a known manner (so-called active load balancing). In addition to the switch for the isolating circuit N14, a further switch can also be provided for the second, opposite pole (all-pole switching). The diagnostic unit N12 can be used in a known manner for cell analysis, e.g., an impedance measurement using, for example,Impedance spectroscopy. For this purpose, the diagnostic unit N12 can determine a measuring current I' and an individual voltage V at several frequencies f for each user unit 12 for an impedance spectral analysis (0 Hz to e.g. 3 kHz), which results in the impedance curve over the frequency f. This represents an impedance spectrum. The diagnostic unit N12 can signal a current state value 29 of a measuring current I' and / or the individual voltage V and / or the measured impedance to the control device 19 via the communication device 27. The term "impedance" in the context of the invention means an impedance value at a predetermined frequency, e.g. 0 Hz, or an impedance curve over the frequency f. Several frequencies can be checked in a frequency sweep with a step-by-step increase or decrease. Alternatively, a multi-frequency excitation can be provided at several frequencies simultaneously. The multi-frequency excitation can, for example,be designed as a multi-sine excitation or as a square wave signal or as a step signal.

[0071] Each utility unit 12 can thus be individually monitored, for example, with respect to its SoH (State of Health - wear and tear) and / or SoC (State of Charge - energy supply capacity) and / or SoF (State of Function - performance, power output capability). The SoH, SoC, and SoF parameters are known per se from the prior art.

[0072] Independently of the impedance measurement, the individual voltage V of the user unit 12 can also be measured without the AC voltage of the impedance measurement. A user unit 12 that is bridged (by means of the bridging circuit N11) can also be monitored with regard to its individual voltage V. Before switching on (closing N14 or switching it electrically conductive), the individual voltage V of the user unit 12 can be individually adjusted using the load balancing N13. Optionally, an electrical charging unit can also be provided for each user unit 12, which can individually charge the user unit 12 even when the semiconductor switch of the isolating circuit N14 is open (each user unit 12 can thus be charged individually). The charging unit can be supplied with energy, for example, via the communication device 27 (e.g., using Power over Ethernet technology) or by means of a galvanically isolated power supply unit.

[0073] Mutual locking of N11 and N14 can be provided (e.g. by software or by means of a logic circuit) to prevent a short circuit.

[0074] In addition, a temperature measurement can be provided by the diagnostic unit N12 or, for example, by the control device 19, a conclusion about the temperature from the impedance.

[0075] The control device 19 thus has access to each individual user unit 12 via the communication device 27. The status of each user unit 12 can be read, and the switching device N10 of each user unit 12 can be controlled, in particular the bridging circuit N11 in combination with the isolating circuit N14. By switching the bridging circuit N11 and the isolating circuit N14 together, a user unit 12 in the series circuit can be alternately connected and disconnected.

[0076] On this basis, the wear / condition of each user unit 12 can be determined centrally in the control device 19 (e.g., in the form of impedance as a wear value), and the switching state of each user unit 12 can be adjusted depending on the determined condition. Individual user units 12 can be electrically removed from the string 11 (bridge N11), inserted (connected in series), individually discharged (discharge resistor R, balancing circuit N13), or temporarily electrically disconnected (open N14 / switch electrically blocked), e.g., for the diagnostic unit N12.

[0077] This makes it possible to react to varying levels of wear / individual parameter variation of the user units 12 in line 11: Preferably, only user units 12 with similar parameter values ​​are actively operated. The similarity can be defined by a similarity criterion that, for example, specifies a maximum difference in at least one parameter, whereby the difference can be in a range from 10% to 100% (double / half). An old / weak user unit 12 is initially bridged / switched out. This can be detected by a performance criterion that, for example, relates to the impedance or is defined by the fact that the similarity criterion is violated. The performance criterion therefore excludes user units 12 that are too weak.The connection of old user units 12 / weak user unit 12 will be possible again later as soon as the line conditions are met, i.e. the remaining user units 12 are also worn out to such an extent that the similarity criterion is met again.

[0078] The similarity criterion can reduce the need for load balancing. The power per load unit (current I in the string is the same, but with different voltages the power output varies, which leads to local heating and thus aging / wear) can be adjusted in advance. This is because load balancing requires adjustment to the "weakest" load unit, which therefore generates the lowest voltage, i.e. it must be reduced to the lowest voltage. By creating identical or similar operating conditions in advance using the similarity criterion, less balancing is required. For example, if the individual voltages V=4.1 volts and V=3.9 volts are present in a string, balancing would have to be adjusted to the weakest load unit, i.e. 3.9 volts.By measuring internal resistance (impedance spectroscopy), the weakest load unit (highest internal resistance) can be identified (performance criterion) and removed from line 11 (bridging N11). However, impedance is only one example of detecting a weak load unit. In general, the weakest load unit can be identified depending on the state of the load unit.

[0079] By electrically decoupling / separating N14 of all service units 12 of a line 11, line 11 can also be switched off from the HV voltage. All service units 12 are decoupled from each other. In this safety mode, line 11 can be secured, for example, for assembly, accident prevention, an emergency, or transport. The switching sequence is important: First, the mechanical switching units 15 (contactors) are opened, then N14 of the service units 12 are decoupled one after the other.

[0080] The control device 19 can also provide wear leveling of the individual user units 12. Wear leveling provides for the homogeneous use of the array / array of user units 12. This achieves wear leveling during operation of the user units 12. Wear leveling from FLASH memory technology (https: / / en.wikipedia.org / wiki / Wear_leveling) can serve as a model.

[0081] The advantage of equalizing wear is the extension of the overall service life of the energy supply device 10, since the probability of failure of individual user units 12, which can be caused by above-average wear of an individual user unit 12, is reduced.

[0082] The supply / removal of energy, i.e., the energy exchange E with a connected device 100, occurs via the next user units 12, which are next in line according to wear leveling. For this purpose, a current wear level is specified for each user unit 12 as a wear value. The goal of these measures is therefore uniform wear. The wear value can be represented, for example, by the impedance of user unit 12. The wear value indicates the wear of user unit 12.

[0083] For each user unit 12, a respective target value for at least one operating variable, e.g. the current I during discharging and / or the individual voltage V during charging, can be determined on the basis of an adjustment criterion depending on the wear value. The adjustment criterion provides that by setting each target value, one or some or all of the user units 12 as a whole complete the energy exchange E, but a difference in wear of the user units 12 calculated from all wear values ​​is kept to a minimum. The wear of the user units 12 is therefore adjusted during the energy exchange E in that more heavily worn user units 12 are subjected to less load than less worn user units 12. The latter wear further in the process, whereby their state of wear approximates that of the less heavily loaded user units 12.

[0084] The wear rate changes during operation, and this changes even more rapidly if the operating point of the wear unit 12 deviates from an ideal state (the wear unit continues to wear). Therefore, protective measures are also advisable.

[0085] For this purpose, the user units 12 are preferably operated only within a tolerance interval around an ideal charge state, which may, for example, be at a charge state of 50%, and / or may specify a current profile of an electrical current flowing in the user unit 12 during the energy exchange.

[0086] In general, the ideal state depends on the technology used in the unit and is known in the state of the art. For battery modules, the ideal state can be defined by the following parameters: SoC - State of Charge (energy content) - ideal is 50%; DoD - Depth of Discharge - degree of discharge (current profile) e.g. ideal charge level 50% minus maximum 20% (tolerance interval). The ideal values ​​given depend on the electrochemistry and / or the intended application and must be determined by a specialist for the specific energy supply device.

[0087] In general, the DoD should remain "low," meaning it should not drop too far. The further the current operating point is from the ideal state, the faster the wear value increases. The current operating point can be adjusted by adjusting the charging current / discharging current I for the load units 12 accordingly. The AC / DC converter arrangement 24 can be used to adjust the charging current, and the DC / DC converter 14 can be used to adjust the discharging current. The wear states / wear values ​​of all load units should be equalized.

[0088] A further protective measure is the following: An excess capacity of user units 12 can be maintained. Without an additional switch, the load can be distributed by means of an excess capacity of user units 12. This results in a lower load per user unit 12 because all user units are always used to ensure even wear. However, the service life is also extended simply because of the lower load; for example, if only 100% (nominal value) is used per string at 110% capacity (sum of the individual capacities of the user units 12 in the string) with throttling by the control device 19, this results in a lower peak load per user unit 12. String 11, for example, supplies a higher voltage than required, so less current I must flow for the same power than when only 100% of the nominal value (nominal capacity) is used.An example: 12 usable units are provided, but a nominal value of only 10 usable units is made nominally available.

[0089] Without a switch, 12 units must be connected, but the capacity for only 10 units is accessed electronically (no switching required!). This also allows for lower-power units, as their peak currents are lower, due to the resulting higher phase voltage U, since more units are connected in series than nominally available. The use of cheaper units is possible.

[0090] If switches are available, e.g. semiconductor switches T, switching between the power units 12 of a string 11 can be provided, e.g. 10 power units are always provided (gives the nominal capacity) and 2 power units are bridged.

[0091] Providing excess capacity of utilization units 12 means that the sum of the individual capacities of the utilization units 12 (i.e., their combined gross capacity) is greater than the nominal capacity made available externally. This can also compensate for a failure of a utilization unit. For example, the energy supply device 10 can be provided as an energy storage device (e.g., battery storage) with a stated or nominal nominal capacity (e.g., 100 kWh). In fact, a gross capacity is provided internally that is greater than the nominal capacity made available externally (actual gross capacity of, e.g., 110 kWh, greater than the net capacity of, e.g., 100 kWh). In other words, more utilization units (e.g., battery cell modules) are available than are necessary to provide the nominal capacity.

[0092] For example, only as many usable units as correspond to the nominal capacity are made available for external discharge. These usable units are then called "active units." The remaining (not actively used) storage units are called "reserve units."

[0093] According to Bad Block Management (BBM), defective or worn-out active units are detected and decommissioned. This means that if an active unit (defective wear unit) fails or becomes defective, this failed active unit can be decommissioned and a reserve unit (previously inactive wear unit) can be put into operation as the new active unit. This way, the nominal capacity is maintained despite the failure of one or more wear units. The term Bad Block Management (BBM) comes from flash memory technology (https: / / en.wikipedia.org / wiki / Flash_memory#Memory_wear).

[0094] During normal operation, however, rotation or swapping (e.g., according to a round-robin algorithm or a generally predetermined replacement rule) can also occur between the user units to ensure even wear on all user units. If a reserve unit is then activated to replace a failed active unit, the reserve unit already has similar electrical properties to the other active units because it already has a similar degree of wear (in accordance with the similarity criterion mentioned above). This can reduce the degree of load balancing required in the manner described.

[0095] Due to the division of usable units into active units and reserve units, usable units can be replaced during maintenance even while the energy storage system is in operation without affecting the nominal capacity. Units to be replaced can be separated / taken out of operation as reserve units and then removed / replaced (dynamic unit replacement).

[0096] Bad block management and / or replacement can also be performed group-wise or string-wise, i.e., a group of utility units 12 or the entire series connection 13 of a string is then switched and / or replaced. Bad block management can also be performed within a utility unit 12. For example, in a utility unit 12 configured as a battery module, several battery cells can be provided, e.g., 12 battery cells as a triple series connection of 4 battery cells each in a parallel connection. One parallel connection can then be switched out at a time, e.g., by bridging.

[0097] The following can be provided with regard to charging management for the strings.

[0098] The DC / DC converters 14 can be interconnected via the busbars 18 to transfer energy. A string 11 can thus be charged from multiple sources, e.g., 40 kW from another string 11 and 10 kW from a grid AC / DC converter 24' to provide 50 kW of charging power.

[0099] During power output, a load profile can be smoothed / equalized, for example, by having some strings 11 supply the load while others are already charging and then ready for the next charging process. For example, charging can occur simultaneously with 10A and discharging with 20A (at least one string 11 is charging the device 100, and at least one other string 11 is being charged from the supply network 22). A boost current (short-term peak, e.g., more than a factor of 1.5) can also be generated by connecting a string 11.

[0100] The (thermal / electrical) load on the individual strings 11 can be limited by alternately supplying different strings 11 to a connected device 100 (e.g., charging an electric vehicle). This also allows the DoD (Depth of Discharge) to be limited, e.g., to 20%.

[0101] By means of the mechanical switching units 15 on each string 11, complete galvanic isolation can also be achieved between the strings if they are connected to different busbars. This is a prerequisite for charging multiple devices 100 (e.g., electric vehicles) simultaneously. Each electric vehicle is connected to a different busbar 18', which is galvanically isolated from the other busbars.

[0102] Overall, the example shows how the invention can provide bad block management in an electrical energy supply device.

Claims

[1] Electrical energy supply device (10) with a respective nominal capacity of at least one predetermined electrical characteristic, wherein the respective nominal capacity is provided by means of a plurality of user units (12), each of which has a respective individual capacity relating to the respective characteristic, and wherein a control device (19) is designed to control an energy exchange (E) between the energy supply device (10) and at least one device-external device (100), wherein the sum of the respective individual capacitances of the user units (12) is greater than the respective nominal capacity of the at least one characteristic value, and the control device (19) is configured to limit the respective characteristic value to the respective nominal capacity during the energy exchange (E), and wherein some of the user units (12) in a respective branch (11) are connected to a series circuit (13), and each branch (11) is connected to a busbar arrangement (18) of the energy supply device (10) via at least one galvanically isolable switching unit (15), and within each branch (11) a bridging circuit (N11) is provided for each user unit (12), and the energy supply device (10) carries out the energy exchange (E) via the busbar arrangement (18), and the control device (19) is configured toto control the at least one switching unit (15) and the bridging circuits (N11) of each strand (11) to limit the at least one characteristic variable, characterized by , that each strand (11) is connected to the busbar arrangement (18) via a DC-DC converter (14) and the control device (19) is designed to control the DC-DC converters (14) to limit the at least one characteristic variable, wherein the control device (19) is designed to determine a respective wear value for each user unit (12) and to deactivate one of the user units (12) whose wear value meets a predetermined wear criterion by electrically disconnecting it, and to put at least one use unit (12) that has been taken out of service back into operation by electrically coupling it if its wear value meets a predetermined similarity criterion in comparison with the respective wear value of the use units (12) that are already in operation, by waiting until all other use units have a similar degree of wear. [2] Energy supply device (10) according to claim 1, wherein the at least one characteristic comprises the electrical storage capacity and / or the maximum electrical power and / or the maximum electrical current. [3] Energy supply device (10) according to one of the preceding claims, wherein each useful unit (12) comprises at least one battery cell, in particular a battery cell module or a combination of several battery cell modules, and / or at least one fuel cell and / or at least one solar panel and / or at least one capacitor and / or a generator. [4] Energy supply device (10) according to one of the preceding claims, wherein the control device (19) is configured to electrically connect more user units (12) to the at least one device (100) for the energy exchange (E) than is necessary to provide the respective nominal capacity of the at least one characteristic variable and / or the control device (19) is configured to operate the energy supply device (10) for a predetermined period of time with its gross capacity representing the sum of the individual nominal capacities. [5] Energy supply device (10) according to one of the preceding claims, wherein the control device (19) is configured to electrically connect only some of the user units (12) to the at least one device (100) connected to the energy exchange device (10) in the case of a plurality of energy exchange processes carried out one after the other, and to select the user units (12) to be connected in each case for each of the energy exchange processes in accordance with a predetermined exchange rule. [6] Energy supply device (10) according to one of the preceding claims, wherein the control device (19) is configured to detect a defective user unit (12) and to electrically separate it from the remaining user units and, during operation of the energy supply device (10), to electrically couple the new user unit to the remaining user units after replacing the defective user unit (12) with a new user unit. [7] Method for providing a respective nominal capacity of at least one predetermined electrical characteristic in an electrical energy supply device (10), wherein the respective nominal capacity is provided by means of a plurality of user units, each of which has a respective individual capacity relating to the respective characteristic, and wherein a control device (19) controls an energy exchange (E) between the energy supply device (10) and at least one device external to the device (100), wherein the sum of the respective individual capacities of the user units (12) is greater than the respective nominal capacity of the at least one characteristic and the control device (19) limits the respective characteristic to the respective nominal capacity during the energy exchange (E), and wherein in each case, some of the user units (12) in a respective strand (11) are connected to form a series circuit (13), and each strand (11) is connected to a busbar arrangement (18) of the energy supply device (10) via at least one galvanically isolable switching unit (15), and within each strand (11) a bridging circuit (N11) is provided for each user unit (12), and the energy supply device (10) carries out the energy exchange (E) via the busbar arrangement (18), and the control device (19) is designed to control the at least one switching unit (15) and the bridging circuits (N11) of each strand (11) in order to limit the at least one characteristic variable, characterized by , that each strand (11) is connected to the busbar arrangement (18) via a DC-DC converter (14) and the control device (19) controls the DC-DC converters (14) to limit the at least one characteristic variable, wherein the control device (19) is designed to determine a respective wear value for each user unit (12) and to decommission one of the user units (12) whose wear value meets a predetermined wear criterion by electrically disconnecting it and to recommission at least one decommissioned user unit (12) by electrically coupling it if its wear value meets a predetermined similarity criterion in comparison with the respective wear value of the user units (12) already in operation, by waiting until all other user units have a similar degree of wear.

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