Modular battery storage system having rechargeable energy storage modules and method for operating a battery storage system

Abstract

To provide a modular battery storage system including an array of n rechargeable energy storage modules and a method of operating the same.SOLUTION: In a modular battery storage system 100 having an array of n rechargeable energy storage modules 110, the energy storage modules are assigned to each individual one a switch 120 by means of which the respective energy storage module can be activated and deactivated. The n energy storage modules can be interconnected via switches in such a way that the sum of the individual voltages Usingle of the active energy storage modules can result in a total voltage UTotal. The battery storage system 100 also includes a control device 130 that controls the switches. The housing 240 encloses the pulse width modulation switch 210 and the like, and shields electromagnetic interference radiation 280.EFFECT: To solve a problem related to electromagnetic interference.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a modular battery storage system including an arrangement of n rechargeable energy storage modules, and to a method of operating such a modular battery storage system. [Background technology]

[0002] A modular battery storage system includes an array of n energy storage modules, where n is at least 2. The energy storage modules are designed to be rechargeable. Within a battery storage system, the energy storage modules are typically connected by parallel and / or series interconnections. An energy storage module may include individual electrochemical cells or assemblies of two or more cells. Within such assemblies, the individual electrochemical cells may then be connected by parallel and / or series interconnections.

[0003] Such battery storage systems are mostly used as DC sources. However, they can also be connected to an AC grid using a multilevel converter. In such converters, the voltages of the individual energy storage modules are added with a time delay for different periods. If the voltages of the individual energy storage modules are sufficiently small compared to the total added voltage, for example, a sinusoidal voltage characteristic can be generated to a good approximation.

[0004] WO 2018 / 162122 A1 describes a modular battery storage system in which each individual energy storage module is assigned a switch that can activate and deactivate each energy storage module. The energy storage modules are interconnected in such a way that the individual voltages of the activated energy storage modules can sum to a total voltage. In this case, at least one performance value is determined for each of the energy storage modules, and a time-varying total voltage is generated by operating at least two energy storage modules that overlap in time for activation periods of different lengths. Each performance value assigns activation periods of different lengths to the individual energy storage modules, allowing various types of energy storage modules to be successfully integrated into the system.

[0005] In such a modular battery storage system, the total voltage can be gradually increased or decreased by connecting the energy storage modules in series, so that a so-called stepped voltage can be generated that approximates a half-wave of a sine wave. In principle, any curve shape can be generated by appropriately switching on and off the power of individual energy storage modules at the appropriate times.

[0006] However, by turning the energy storage modules on and off or activating and deactivating them, only a rough approximation of the desired output voltage is possible. Therefore, it is already known to perform pulse width modulation (PWM) on the individual generated voltages to further approximate the stepped voltage achievable by appropriate switching of the energy storage modules. For example, the above-mentioned WO 2018 / 162122 A1 already describes that each switch assigned to an individual energy storage module is designed to perform such pulse width modulation. As a result, the individual voltages thus modified can sum to a total voltage, thus further approximating the desired sine wave of the voltage.

[0007] Generally, high frequencies are required to perform pulse width modulation. However, this creates problems as high frequencies have a negative impact on electromagnetic compatibility (EMC) and require complex shielding measures. However, under certain circumstances, even sophisticated shielding measures cannot solve these problems, and as a result, the functionality and possible applications of the battery storage system as a whole are actually severely limited. Furthermore, the heating associated with high frequencies requires cooling of the individual energy storage modules.

[0008] WO 2018 / 162122 A1 already suggests that, if necessary, only one of the switches assigned to the energy storage module can be designed for PWM generation. Nevertheless, this does not provide a satisfactory solution to the problems that arise in this type of battery storage system, in particular those related to electromagnetic interference. Summary of the Invention [Problem to be solved by the invention]

[0009] In contrast to this, the present invention sets itself the task of providing an improved modular battery storage system that, on the one hand, offers a cost-effective solution and, on the other hand, is very robust and less susceptible to failures during operation. In particular, the battery storage system should be able to supply the voltage generated by the individual energy storage modules to the AC grid. [Means for solving the problem]

[0010] This object is achieved by a modular battery storage system having the features of claim 1 and by a method for operating such a modular battery storage system according to the further independent claims. Preferred embodiments of the modular battery storage system and of the method for operating this battery storage system are the subject of the dependent claims.

[0011] The modular battery storage system according to the invention comprises n rechargeable energy storage modules. In this context, the modular battery storage system according to the invention comprises: each of the energy storage modules includes at least one (preferably several) rechargeable energy storage element; and Each individual one of the bn energy storage modules is assigned a switch that can activate and deactivate each energy storage module; and cn energy storage modules are operated by the individual voltage U single The total voltage U Total and d. The battery storage system includes a control device that controls switches associated with the n energy storage modules. It always has the following characteristics.

[0012] The essence of the invention is that the modular battery storage system includes a modulation unit (feature e.) characterized by the following features i. to iii. i. The modulation unit is Total connected to n connectable energy storage modules in such a way that ii. the modulation unit includes a pulse width modulation switch; and iii. The modulation unit includes a housing adapted to enclose the pulse width modulation switch and to shield electronic components outside the housing from electromagnetic interference radiation emanating from the pulse width modulation switch.

[0013] Switches for pulse width modulation are prior art and commercially available. According to the present invention, the modular battery storage system according to the present invention is characterized by at least one of the following additional features a. to c. a. The pulse width modulation switch includes a plurality of semiconductor switches. b. The pulse width modulation switch includes an H-bridge circuit with four semiconductor switches. The cH bridge circuit includes two wire branches each having two semiconductor switches connected via a capacitor. It is particularly preferable that the immediately preceding features a. to c. be combined and realized in the present invention.

[0014] The semiconductor switches are preferably MOSFETs, but as an alternative to these MOSFETs, bipolar transistors, in particular bipolar transistors with insulated gate electrodes (IGBTs), can also be used as semiconductor switching elements.

[0015] In a further preferred embodiment, the modular battery storage system according to the invention has at least one of the additional features a. and b. immediately below. a. The modulation unit includes a filter choke connected downstream of the pulse width modulation switch in the discharge direction. b. The housing further seals the filter choke. Particularly preferably, the immediately preceding features a. and b. are realized in combination in the present invention.

[0016] By activating and deactivating the individual energy storage modules, the modular battery storage system according to the invention can generate a stepped overall voltage that is converted by the modulation unit and the pulse-width modulation switches contained in the modulation unit into an overall pulse-width modulated voltage curve that closely matches the desired voltage curve. Pulse-width modulation (PWM) smooths the transitions between the individual voltage steps. The voltage waveform is further smoothed by downstream filter chokes, resulting in the desired waveform. This allows, for example, the DC voltage generated by the individual energy storage modules to be converted into a sinusoidal waveform in a particularly advantageous manner, which can then be fed into the AC grid.

[0017] A particular advantage of the battery storage system according to the invention is that the PWM is performed at a central point in the modulation unit that supplies the individual voltages that are summed. The modulation unit therefore combines a pulse width modulation switch with a downstream filter choke, allowing for smoothing of the curve and therefore the supply to the grid, and this modulation unit as a whole is shielded by a suitable housing, in particular a metal housing, in such a way that electromagnetic interference radiation generated during this process is reliably blocked and does not penetrate to the outside. Preferably, the housing of the modulation unit encloses both the pulse width modulation switch and the filter choke. In some preferred embodiments, a control device is further disposed within the housing.

[0018] PWM in a central location avoids the need to perform such pulse width modulation in individual energy storage modules, which involves various problems. In particular, it avoids the generation of distributed electromagnetic interference. Electromagnetic shielding requirements are therefore limited to the modulation unit, and as a result, all other components of the battery storage system can be designed to be much simpler and less expensive.

[0019] The central implementation of PWM in the modulation unit of the modular battery storage system according to the invention is associated with significant cost advantages. For example, if PWM is performed in the individual energy storage modules or associated switches, as in the prior art, significant costs must be incurred due to the high-speed switching elements and high-speed, powerful drivers required for this purpose. On the other hand, in the modular battery storage system according to the invention, the individual energy storage modules can be designed in a much simpler way, since the associated switches only need to be able to power the energy storage modules on and off or activate and deactivate them. Low-cost switches operated at a relatively low clock frequency can be used for this purpose.

[0020] The high frequencies required for PWM in the individual energy storage modules of conventional systems are also associated with a large amount of heat generation around the system in conventional modular battery storage systems, which needs to be regulated by an appropriate cooling system. This cooling system can be omitted in the modular battery storage system according to the invention, with only the cooling of the modulation unit being required at most. This is also associated with significant cost advantages.

[0021] In conventional modular battery storage systems using PWM on the switches of the individual energy storage modules, significant interference can be observed as a result of PWM clocking in the extensive wiring of such battery storage systems due to pulsating electromagnetic fields, which on the one hand can have a disruptive effect on the functioning of the system itself and, on the other hand, must be shielded from the outside in order to be able to comply with electromagnetic compatibility standards. Such shielding poses significant problems, especially due to the large spatial requirements of such systems. This problem is almost completely avoided in the modular battery storage system according to the invention, since, in principle, it is only necessary to electromagnetically shield the modulation units.

[0022] The precise PWM ratio control at exactly the right time for each energy storage module required in conventional modular battery storage systems with PWM circuits assigned to each individual energy storage module is complex and requires real-time communication and data transmission. This aspect is also omitted in the modular battery storage system according to the present invention, so that embodiments of the modular battery storage system can further be designed in a much simpler and more robust manner in this respect compared to conventional systems. In particular, errors in the PWM of individual energy storage modules are eliminated, which in conventional systems can cause network failures, operational failures during operation of the battery storage system itself, and even system hardware failures.

[0023] Another particular advantage of performing PWM at a central point in a remote modulation unit of a battery storage system is that optimal electromagnetic shielding is possible at the remote modulation unit, allowing PWM to be performed at very high frequencies. This allows downstream filter chokes, which are most effective at high frequencies, to be designed to be relatively small. This is particularly advantageous because filter chokes are typically the most cost-intensive component of a system as their size increases. The modulation unit can be constructed very compactly, further simplifying shielding against electromagnetic interference radiation.

[0024] By avoiding high frequency currents and voltages in the individual energy storage modules, electromagnetic compatibility is significantly improved compared to conventional systems, and the amount of shielding and filtering required is significantly less than in conventional systems. Cabling requirements for the energy storage modules are also reduced, and particularly advantageously, shielding for signal lines can be eliminated.

[0025] Overall, in a modular battery storage system according to the present invention, the individual energy storage modules can be designed much more simply than in conventional battery storage systems. The associated savings increase with the number of individual energy storage modules. For example, conventional technologies can be used to manufacture the energy storage modules because no intelligence is required for the energy storage modules, and simple, inexpensive hardware and little software effort is required for the individual energy storage modules. Furthermore, less cooling effort is required for the individual energy storage modules, and therefore for the entire system. Complex, time-critical communication between the control device and the individual energy storage modules is not required. For example, no data bus is required to control the individual energy storage modules. Overall, therefore, the battery storage system according to the present invention can be manufactured in a much more trouble-free and cost-effective manner.

[0026] Possible configurations of the energy storage modules of the battery storage system according to the invention will first be described. The described configurations are also preferred in the context of the modular battery storage system according to the invention. The energy storage elements can be, for example, aged energy storage elements with already reduced capacity that originate from other applications (e.g., automotive applications) and can continue to be used appropriately by being used in such a modular battery storage system. Particularly preferably, the energy storage modules usable according to the invention comprise electrochemical cells, in particular based on lithium-ion technology and / or nickel-metal hydride technology.

[0027] All energy storage modules included in the battery storage system have the same individual voltage U single However, this is not necessarily the case. Conversely, different individual voltages U single It may be preferable to install an energy storage module with a total voltage U Total This increases the number of possible variations of

[0028] Preferably, the switches are designed in such a way that each allocated energy storage module can also be operated with reverse polarity. In particular, different individual voltages U single If an energy storage module with a total voltage U is installed simultaneously in the same system, this also Total This increases the number of possible variations of the individual voltages U of the energy storage modules operated in reverse polarity. single is the total voltage U Total This is particularly advantageous as it makes a negative contribution to

[0029] If one of the n energy storage modules is deactivated, the energy storage module will TotalIn a particularly preferred embodiment, the switch is designed so that an energy storage module belonging to the switch can be bypassed if necessary: ​​the bridged, inactive energy storage module is no longer electrically connected to the other energy storage modules of the array.

[0030] The modular battery storage system according to the invention can include a large number of energy storage modules. Typically, the variable n is a value in the range of 2 to 100,000, preferably in the range of 2 to 10,000, and particularly preferably in the range of 2 to 1,000. Within these ranges, it is further preferred that the variable n is a value in the range of 5 to 100, particularly preferably in the range of 5 to 20, and in particular in the range of 7 to 10.

[0031] In a preferred manner, the modular battery storage system according to the invention has at least one of the following additional features a. to c. a. The modulation unit includes a low-pass filter connected upstream of the pulse width modulation switch in the discharge direction. b. The modulation unit includes a low-pass filter connected downstream of the pulse width modulation switch in the discharge direction. c. The housing further encloses the low pass filter and / or the low pass filter.

[0032] In a preferred embodiment, the low-pass filters connected upstream and / or downstream of the pulse-width modulated switch can be conventional low-pass filters that attenuate the high-frequency components of the total voltage to a cutoff frequency in the range of 100 kHz to 1 GHz. Low-pass filtering before introducing the total voltage into the pulse-width modulated switch has the particular advantage that PWM in the pulse-width modulated switch is less complex as a result of the reduction in high-frequency components.

[0033] In a particularly preferred manner, as an alternative to or in addition to the upstream low-pass filter, a low-pass filter having the described characteristics is also provided downstream of the filter choke. In a particularly preferred manner, a low-pass filter is provided at the input of the modulation unit and another low-pass filter is provided at the output of the modulation unit.

[0034] Preferably, the filter choke differs from the low pass filter in that the filter choke is designed to smooth out relatively low frequency components in the frequency range from 1 kHz to 10 MHz, particularly for the converter clock frequency and small harmonics.

[0035] A particularly suitable filter choke preferably has a ferromagnetic core designed to be effective at the converter's clock frequency and its small harmonics. Preferably, the suitable material has a high magnetic permeability, so that the number of turns can be kept low and copper losses are kept within limits. Such cores, also known as "power ferrites," are largely ineffective in the EMC-relevant high-frequency range, e.g., the MHz range. Despite the fact that the copper windings are kept as small as possible due to the high magnetic permeability of the soft magnetic core, the windings suffer from a relatively high parasitic capacitance that, in effect, bridges the filter choke for high frequencies, thus rendering it ineffective. Overall, the filter choke preferably filters lower frequency components.

[0036] The preferred low-pass filter is sometimes called an EMC filter, since the low-pass filter preferably eliminates electromagnetic interference. Preferably, the low-pass filter or filters have a coil core suitable for high frequencies. On the one hand, these materials generally have significantly lower permeability and saturation magnetic flux density than the "power" materials described, resulting in a material with very low inductance at the fundamental frequency. However, on the other hand, the material is particularly effective at EMC-relevant high frequencies. In particular, the low-pass filter is characterized by low-capacitance windings. Due to the core material, the material has low inductance.

[0037] Preferably, the low-pass filter or filters further include a smoothing or bleed capacitor. Furthermore, the low-pass filter may also have an additional current-compensating choke and, if necessary, a Y capacitor effective for common-mode interference. In this case, the current-compensating choke provides a suppression impedance for any common-mode interference that occurs. The Y capacitor dissipates what is left to ground.

[0038] The design of a pulse-width-modulated switch as an H-bridge circuit with four semiconductor switches is, in principle, comparable to the basic electronic structure of a known multilevel converter stage. Advantageously, the voltage across the capacitor is regulated or controlled by driving the power semiconductor devices with pulse-width modulation. This has the particular advantage that the capacitor does not require a dedicated charging circuit.

[0039] In a particularly preferred embodiment of the modular battery storage system according to the invention, the battery storage system has, with respect to the modulation unit, at least one of the following additional features a. and b. a. The modulation unit includes a cooling device. b. The cooling device is assigned to a modulation unit.

[0040] In principle, high-frequency currents occurring exclusively in the area from the modulation unit in the modular battery storage system according to the invention can cause heat generation in the modulation unit, which is appropriately countered by a cooling device that cools the modulation unit. This cooling device can be arranged in the housing of the modulation unit or it can be an external cooling device assigned to the modulation unit. For example, cooling circuits or other cooling elements known per se can be used for this purpose.

[0041] In a particularly preferred manner, the modular battery storage system according to the invention is characterized by at least one (preferably both) of the following additional features a. and b. The switches assigned to the an energy storage modules are not set up for pulse width modulation. bn energy storage modules have no passive cooling devices or only one passive cooling device, or n energy storage modules have no passive cooling devices or only one passive cooling device.

[0042] The fact that the n energy storage modules of the battery storage system according to the present invention are not set up for pulse-width modulation means that the energy storage modules can be configured very simply and do not require any complex circuitry, allowing for significant savings in the modular battery storage system according to the present invention. According to the inventive concept, pulse-width modulation is performed centrally in the modulation unit, eliminating the need for complex pulse-width modulation switches in the individual energy storage modules. This has various advantages. In addition to the potential savings noted above, there is a further particular advantage with regard to heat generation in the modular battery storage system according to the present invention. By eliminating pulse-width modulation in the individual energy storage modules, no high-frequency currents are required in the area, and there is no excessive heat generation in the energy storage modules, eliminating the need for sophisticated cooling systems or equipment. In preferred embodiments, low-cost cooling means (e.g., extended copper areas on the printed circuit board and / or soldered SMD (surface-mounted device) heat sinks) are provided in the energy storage modules sufficient to compensate for the resulting conduction losses. Furthermore, cooling means may be necessary or useful to compensate for resistive losses during operation of the energy storage elements in the individual energy storage modules.

[0043] In a particularly preferred manner, the modular battery storage system according to the invention is characterized by the immediately following additional feature a. with regard to the control of the energy storage modules. a. A signal line is provided to control a switch assigned to the energy storage module.

[0044] Since pulse width modulation is not performed on the individual energy storage modules but only at a central point in the modulation unit, the control of the individual energy storage modules can also be designed very simply. This is particularly advantageous if only 0 / 1 signal lines are provided to control the switches assigned to the energy storage modules. For example, a relatively slow common bus system can be used to control the switches of the individual energy storage modules, since only one connection and disconnection of the individual energy storage modules is required. On the one hand, this embodiment of the control of the energy storage modules is in principle sufficient for the operation of the modular battery storage system according to the invention, and on the other hand, it allows for significant cost savings.

[0045] In a preferred embodiment, optical fiber can be used for the 0 / 1 signal lines instead of conventional copper wires to improve immunity to interference. Although optical fiber is slightly more expensive than copper wire, it already has inherent galvanic isolation and is, in principle, immune to electromagnetic interference. Since high clock speeds are generally not required for a system according to the invention, the required transceivers can be designed very simply and therefore at low cost.

[0046] As an alternative to 0 / 1 signal lines, so-called tristate elements can also be used: these are digital switching elements whose output can assume not only 0 and 1, but also a third, high-impedance state.

[0047] In a particularly preferred embodiment of the modular battery storage system according to the invention, the system always has the additional feature a immediately following. a. The control device measures the time-varying total voltage U Total(t) is configured to operate at least two of the energy storage modules for different lengths of activation periods via respective allocation switches that overlap in time.

[0048] Time-varying total voltage U Total (t) can be generated with essentially any voltage waveform, so a sawtooth voltage can be generated to as good an approximation as a triangular voltage. Particularly preferably, U Total (t) is in particular a voltage having a sinusoidal voltage characteristic, as already mentioned at the beginning. In a preferred embodiment, the modular battery storage system according to the invention can therefore be operated in a discharge mode, feeding current from a DC power source into an AC network with conversion of DC voltage to AC voltage.

[0049] In addition to the control of the energy storage modules, in a particularly preferred manner the modular battery storage system according to the invention is further characterized by the following additional features with regard to the function of the control device. a. The control device is configured to control a pulse width modulation switch in the modulation unit.

[0050] Thus, in this preferred embodiment, the control device takes over both the control and switching of the n energy storage modules and the control of the pulse width modulation switches in the modulation unit. In the case of direct control of the pulse width modulation switches, a signal bus designed for high speed is preferably provided. In the case of control of the n energy storage modules, the transmission of a simple 0 / 1 signal using a low frequency is sufficient.

[0051] In preferred embodiments, the control device of the modular battery storage system always has one of the following additional features: The control device is a signal processor. b. The control device is a microcontroller.

[0052] The present invention further includes a method of operating a modular battery storage system according to the above description. In a particularly preferred method, the method includes the immediately following steps a. and b. generating a stepped voltage by sequentially activating and deactivating an energy storage module; and b. The stepped voltage is fed to a modulation unit and converted into a smoothed sinusoidal voltage by pulse width modulation and at least one filtering.

[0053] In a particularly preferred manner, the smoothed sinusoidal voltage can be fed as a phase into an AC power grid. Thus, the DC voltage generated by the individual energy storage modules can be converted into an AC voltage by appropriate sequential control of the individual energy storage modules and used in the corresponding power grid. Similarly, the system is also suitable for operating polyphase systems, for example for generating three-phase currents.

[0054] Additionally, the system can be used to provide DC applications (e.g., charging electric vehicles or otherwise). However, the system can also be used, for example, to supply and draw DC voltage from a photovoltaic system without the need for any structural modifications. Electricity stored in this way can be supplied to the grid as AC or used as DC, for example, to charge electric vehicles.

[0055] Thus, a system according to the invention can be designed, for example, as a charging device for electric vehicles, with its multilevel inverter designed to supply DC or AC voltage in a configurable manner via software, which means that a single charging device with a single power electronics system can serve different charging systems.

[0056] In principle, any other waveform can also be generated when operating the modular battery storage system according to the invention, for example the modular battery storage system according to the invention is also suitable for generating DC voltages that can be used, for example, for photovoltaic system applications or for charging electric vehicles or for other purposes.

[0057] In a particularly preferred manner, the method according to the invention always has the additional feature a immediately following. a. The energy storage modules of the modular battery storage system are driven at a frequency between 50Hz and 500Hz (particularly, 100Hz).

[0058] A circuit with a frequency of 100 Hz is particularly advantageous, since this frequency corresponds to a half-wave frequency in the domestic grid, so that the AC voltage generated by such a circuit of an energy storage module can be fed into the domestic grid as single phase without further effort.

[0059] In a particularly preferred manner, the method according to the invention further comprises the additional feature immediately below. a. The pulse width modulation switch of the modulation unit is driven at a high frequency.

[0060] Preferably, the high frequency driving the pulse width modulated switch is in the range of 1 kHz to 1 MHz. The actual frequency range selected will be appropriately adapted to the circuit and / or semiconductor technology used. In a particularly preferred embodiment, the frequency is in the range of 10 kHz to 200 kHz.

[0061] Due to the high frequencies used to control the pulse-width modulation switches, the effectiveness of downstream filter chokes is particularly high, so that the size of the filter chokes can be further reduced at high clock frequencies for the pulse-width modulation. The reduction in the size of the filter chokes therefore offers particular savings potential in embodiments of the modular battery storage system or in embodiments of the modulation unit according to the invention, so that high clock frequencies are particularly preferred when driving the pulse-width modulation switches. For embodiments of the battery storage system according to the invention, and in particular for the housing of the modulation unit, electromagnetic interference radiation associated with high frequencies is not an issue, since corresponding embodiments with shielding elements, for example by a metal housing, are possible without much effort due to the compact design of the modulation unit.

[0062] In a preferred embodiment, the housing is a metal housing, but it is also possible to provide for the housing, or at least for the shielding elements of the housing, to use metallized plastic, i.e. the housing consists of plastic parts with a metal coating.

[0063] In a preferred embodiment, the housing is designed to shield the power electronics in such a way as to essentially completely enclose and form a Faraday cage without any slits or other openings that could form resonances or antennas at the frequencies generated. Furthermore, a metal grid covering the ventilation openings can be provided, for example, as a shielding means.

[0064] In a particularly preferred embodiment of the system, data communication is performed with the individual energy storage modules. However, compared to conventional systems, the corresponding communication bus can be designed to be much simpler. In particular, real-time capable data transmission is not required, and as a result, the preferred data communication line is not real-time capable. For example, low-cost interfaces (e.g., CAN or RS485) can be used in this situation.

[0065] In a further preferred embodiment of the modular battery storage system according to the invention or in a preferred embodiment of the method for operating such a battery storage system, it may also be provided that at least one performance parameter or at least one performance value is determined for each of the n energy storage modules. Depending on the determined performance parameter, different lengths of operating periods can be assigned to the individual energy storage modules. In other words, depending on the at least one performance parameter, an assignment is made as to which energy storage modules are operated for short periods (short operating periods) and which energy storage modules are operated for longer periods (longer operating periods).

[0066] Generally, the actual remaining capacity (state of charge, or SOC for short) and maximum available capacity (state of health, or SOH for short) of the energy storage modules included by a battery storage system are useful for the operation of the battery storage system. A potential problem here is that the SOC and SOH of individual energy storage modules in a battery storage system may diverge significantly, for example, as a result of different aging rates. Generally, the energy storage module with the worst performance value determines the overall performance of the battery storage system.

[0067] It is known to use balancing systems to equalize the charge and / or voltage between energy storage modules having unequal charge and / or voltage states, but such balancing systems are not inexpensive to implement due to the significant associated hardware and software costs.

[0068] In preferred embodiments of the modular battery storage system according to the invention or in preferred embodiments of the method according to the invention, when controlling the individual energy storage modules, performance parameters can be taken into account to compensate for unequal charge and / or voltage conditions.

[0069] The performance values ​​or parameters are state values ​​that are characteristic of the performance of the energy storage modules. In particular, the performance value or parameter can be the current SOC or current SOH of each energy storage module at the time of the determination. However, the at least one performance value can also be a value that correlates with the current SOC and / or current SOH of each energy storage module.

[0070] There are several known procedures for determining SOC. For example, if the discharge voltage is measured, a known discharge curve can be used to infer the current SOC value. However, in the context of the present invention, the method selected for SOC determination is auxiliary. It is merely important that the determined performance values ​​are comparable to each other, i.e., obtained in a comparable manner, so that the performance of energy storage modules can be compared based on the values.

[0071] Furthermore, there are several known procedures for determining the SOH. One characteristic of the SOH of an energy storage module is the internal resistance of the energy storage module. For example, when the energy storage module is operated under predetermined conditions (temperature, state of charge, discharge current, discharge duration, etc.), a reference value for the internal resistance can be determined. Based on the change in the internal resistance (measured under the same predetermined conditions), the SOH can be inferred. However, in the context of the present invention, the method, if any, selected for SOC determination is also auxiliary. Again, it is merely important that the determined performance values ​​for the energy storage modules of a battery storage system are comparable to each other, i.e., obtained in a comparable manner, so that the performance of the energy storage modules can be compared to each other based on the obtained values.

[0072] Generally, apart from a formation cycle during initial operation of the energy storage module, the SOH of an energy storage module does not change significantly between directly successive charge and discharge cycles. Thus, if at least one performance value is the current SOH or a value correlated to the current SOH, it is generally sufficient to simply determine the performance value at intervals (e.g., at intervals of 10 charge and discharge cycles). As a result, if at least two energy storage modules are assigned operating periods of different lengths, the determined value can be stored and used until it is updated.

[0073] In contrast, SOC can change to a considerable extent over very short periods of time, so it is generally appropriate to determine the current SOC, or alternatively, a value that correlates with the current SOH immediately prior to assignment.

[0074] In a preferred embodiment, the method according to the invention comprises at least one of the following additional steps, particularly preferably all three of the following additional steps: The determined performance value for each of the n energy storage modules is stored in a data memory, so that the n energy storage modules can be sorted according to their performance. · Allocating energy storage modules to operating periods of different lengths based on performance values ​​sorted in a data memory. Allocating energy storage modules with relatively high performance for longer operating periods than energy storage modules with relatively low performance.

[0075] Generally, the operating period correlates with the determined performance capability of each module. For example, if at least one performance value is the current SOH, the energy storage modules can be sorted by increasing SOH. As a result, the maximum SOH value indicates the highest performance capability, and the minimum SOH value indicates the lowest performance capability. In accordance with the present invention, it is preferred to assign the energy storage module with the maximum SOH the longest operating period, while the energy storage module with the minimum SOH the shortest operating period.

[0076] As a result, more powerful energy storage modules are subjected to a higher load during operation than less powerful energy storage modules. As a result of the different loads, the more highly loaded modules age faster on average than the less heavily loaded modules, so that the performance capabilities of the energy storage modules are again matched to each other in the long term. The method according to the invention therefore indirectly ensures the symmetry of the energy storage modules and therefore has an effect similar to that of the balancing system described above.

[0077] Aging energy storage modules from electromobility have the greatest capacity variations. Such aging energy storage modules can also be operated together in a battery storage system without the need for pre-selection, without any problems, according to the method described herein. When an energy storage module reaches the end of its life, it can be easily replaced with a replacement module without the need for expensive backup measures (such as matching). New energy storage modules can also be connected and operated without backup measures, regardless of the initial capacity and production dispersion of the energy storage module.

[0078] Overall, these measures extend the useful life of the energy storage modules used in battery storage systems operated in accordance with the present invention, providing both ecological and economic benefits.

[0079] In a particularly preferred embodiment, the method according to the invention comprises at least one of the following additional steps, particularly preferably all five of the following additional steps: Peak voltage U Ges Determine the number m of energy storage modules required to generate (t). · Select m energy storage modules from the n available energy storage modules. Voltage U Ges Specify the time intervals and activation periods during which the m energy storage modules should be activated to generate the desired voltage curve of (t). Considering the sorting criteria "performance" and "length of the operating period assigned to the energy storage module", sort the selected m energy storage modules in an order in which both of the two sorting criteria increase or decrease in the same direction. The m energy storage modules can be sorted according to the capacity of the energy storage module, and the operating period depending on the length of the energy storage module. The operating periods are assigned to the m energy storage modules. After the assignment, the assignment is done in such a way that sorting the energy storage modules according to the capacity of the energy storage module and the length of the operating period assigned to the energy storage module will yield the same result. Thus, sorting by increasing capacity will result in the longest operating period being assigned to the most powerful module, the second longest operating period being assigned to the second most powerful module, the third longest operating period being assigned to the third most powerful module, etc. · Activate m energy storage modules in this order and at specified time intervals.

[0080] The peak voltage is the maximum instantaneous value of a periodically varying voltage. For a sinusoidal voltage curve, the peak voltage corresponds to the amplitude of the sinusoidal oscillation.

[0081] The same individual voltage U single ), m, the individual voltages U supplied by the individual energy storage modules singleThis is determined by dividing the peak voltage value by the value of

[0082] In a particularly preferred embodiment, the modular battery storage system includes more energy storage modules than are needed to generate the peak voltage. Simply stated, it is preferred that n>m. For example, m energy storage modules may be selected based on available module performance data. For example, m powerful modules may be selected at any one time.

[0083] Of particular advantage, it may also be provided that defective energy storage modules are not taken into consideration in the selection, for example, for this purpose a performance threshold can be defined for each of the n energy storage modules that will cause the energy storage module to be taken out of operation.

[0084] If necessary, provision can be made for a shutdown that triggers a signal or message as a result of the undercut indicating the need for shutdown and / or replacement. In principle, a defective energy storage module can be replaced during operation. For this purpose, it is not necessary to stop the method according to the invention. For this purpose, the switch assigned to the energy storage module has the above-mentioned option for bridging, and the energy storage module is no longer electrically connected to further energy storage modules.

[0085] In further particularly preferred embodiments, the method according to the invention comprises at least one of the following additional features and / or one of the following additional steps: The desired voltage curve is a sine wave. The energy storage module with the highest capacity is activated first, and the energy storage module with the lowest capacity is activated last. The energy storage module with the highest capacity is operated for the longest operating period, and the energy storage module with the lowest capacity is operated for the shortest operating period.

[0086] To generate a sinusoidal half wavelength, it is appropriate that the energy storage module assigned the longest operating period be activated first and deactivated last. Meanwhile, the energy storage module assigned the shortest operating period should be activated last and deactivated first. Therefore, the energy storage module assigned the longest operating period has a relatively high performance. Meanwhile, the energy storage module assigned the shortest operating period may exhibit a relatively low performance.

[0087] In further particularly preferred embodiments, the battery storage system according to the invention has at least one of the following additional features: The array consisting of n energy storage modules only includes lithium-ion type energy storage modules. The array of n energy storage modules includes only nickel-metal hydride type energy storage modules. The array of n energy storage modules includes energy storage modules of various types. The array of n energy storage modules comprises at least one energy storage module having a cathode based on LFP (lithium iron phosphate). The array of n energy storage modules comprises at least one energy storage module having a cathode based on NMC (lithium nickel manganese cobalt oxide). The array of n energy storage modules comprises at least one energy storage module having a cathode based on LTO (lithium titanate). The array of n energy storage modules comprises at least one energy storage module having a cathode based on NCA (lithium nickel cobalt aluminum oxide). The array of n energy storage modules includes at least one Pb / PbO2 type energy storage module.

[0088] In the battery storage system according to the invention, various types of energy storage modules can be easily interconnected. The strength of each type can be used in a targeted manner. Different energy storage modules can be driven according to requirements. For example, energy storage modules with cathodes based on LTO are suitable for absorbing high load peaks. In principle, it is also possible to interconnect nickel-metal hydride type energy storage modules and lithium-ion type energy storage modules in a battery storage system.

[0089] Pb / PbO2 type energy storage modules are conventionally used as individual cells in lead-acid batteries with sulfuric acid electrolyte. Within the scope of the present invention, it is particularly preferred to interconnect at least one Pb / PbO2 type energy storage module with a lithium-ion type energy storage module in a battery storage system. Pb / PbO2 type energy storage modules are particularly suitable for use in apex batteries.

[0090] According to the above, the battery storage system or method according to the present invention has at least one of the following characteristics: Preferably, the various types of energy storage modules are connected to different individual voltages U single It has. Thus, for example, an array of n energy storage modules may include energy storage modules having a nominal voltage of 1.2V (e.g., nickel-metal hydride type energy storage modules) combined with energy storage modules having a nominal voltage of 2V (e.g., Pb / PbO2 type energy storage modules). Preferably, the various types of energy storage modules include energy storage modules selected from the group consisting of lithium-ion type energy storage modules, nickel-metal hydride type energy storage modules, and Pb / PbO2 type energy storage modules. Preferably, the various types of energy storage modules include at least two energy storage modules selected from the group consisting of a lithium-ion type energy storage module, a nickel-metal hydride type energy storage module, and a Pb / PbO2 type energy storage module. Thus, an arrangement of n energy storage modules may, for example, comprise at least one energy storage module of a nickel-metal hydride type having a nominal voltage of 1.2 V combined with at least one energy storage module of a Pb / PbO2 type having a nominal voltage of 2 V, or combined with at least one energy storage module of a lithium-ion type. Alternatively, the arrangement of n energy storage modules may further comprise at least one energy storage module of each of the three types mentioned, or at least one energy storage module of a Pb / PbO2 type combined with at least one energy storage module of a lithium-ion type. The various types of energy storage modules include at least one energy storage module selected from the group consisting of an energy storage module having a cathode based on LFP, an energy storage module having a cathode based on NMC, an energy storage module having a cathode based on LTO, and an energy storage module having a cathode based on NCA.

[0091] In a particularly preferred embodiment, the battery storage system according to the present invention is operated with a battery management system, whereby individual modules are specifically controlled based on measurable parameters of the energy storage cells or energy storage modules.

[0092] Further features and advantages of the invention will become apparent from the following description of an embodiment in conjunction with the drawings, in which the individual features may be realized respectively, separately or in combination with one another. [Brief explanation of the drawings]

[0093] [Figure 1]1 is a full voltage curve of a modular battery storage system. [Figure 2] 1 is a prior art modular battery storage system. [Figure 3] 1 is a modular battery storage system according to a preferred embodiment of the present invention. [Figure 4] 1 is a diagram illustrating the structure of a modulation unit as part of a modular battery storage system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0094] The basic operation of a modular battery storage system is described in detail, for example, in WO 2018 / 162122 A1, which is incorporated herein by reference.

[0095] FIG. 1 illustrates the principle of smoothing or "ramp-down" a stepped voltage 1 that can be generated in a modular battery storage system, specifically to a sinusoidal voltage 2 that can be used to supply an AC grid. A stepped voltage is generated by sequentially powering on and off individual energy storage modules in the modular battery storage system, resulting in a gradual, step-like change in the overall voltage. This stepped voltage 1 is then approximated as a sinusoidal voltage on the power grid. However, switching the energy storage modules only allows a rough approximation to the desired output voltage. Therefore, it is already known to perform pulse-width modulation (PWM) to approximate the stepped voltage 1 to the desired sinusoidal voltage 2, which buffers or compensates for the voltage step. The stepped voltage 1 is just one example of the possibilities of a modular battery storage system. In fact, any curve shape can in principle be generated with the individual energy storage modules of a modular battery storage system.

[0096] 2 illustrates a conventional modular battery storage system having multiple individual energy storage modules 11 each associated with a switch 12. The energy storage modules 11 are rechargeable energy storage modules. Each switch 12 is assigned to exactly one energy storage module 11, and vice versa. Each energy storage module 11 can be activated and deactivated by the switch 12. Each switch 12 can have several switching positions. In a first switching position, the energy storage module 11 assigned to the switch 12 is activated and the individual voltage U of the energy storage module is single In the second switching position, the energy storage module 11 associated with the switch 12 is deactivated and the individual voltage U of the energy storage module single If necessary, a third switching position can be provided which operates the energy storage module 11 assigned to the switch 12 in reverse polarity.

[0097] Advantageously, all switches 12 are configured in such a way that in the event of a malfunction, the energy storage module 11 associated with the switch 12 can be bridged. This means, for example, that a malfunctioning energy storage module 11 can be replaced during operation. The switches 12 are connected in series. Thus, the individual voltages U of the operating energy storage modules 11 single The total voltage U Total The energy storage modules 11 can be connected via the switches 12 in such a way that, when one of the switches 12 is in a second switching position, the switch 12 bypasses the inactive energy storage module 11 assigned to the switch 12. When one of the switches 12 is in a third switching position, the individual voltage U of the energy storage module 11 assigned to the switch 12 is single is the total voltage U TotalBy appropriately operating the individual switches 12 via the control device 13, a stepped voltage can be generated by summing the individual voltages to approximate a sinusoidal voltage curve. When the energy storage module 11 is powered on continuously, the total voltage U increases until it reaches the desired peak value. Total is gradually increased. The total voltage is then gradually decreased by successively deactivating individual energy storage modules.

[0098] To achieve a sufficient approximation to an AC sinusoidal curve, the individual voltages generated are conventionally PWM'd in the individual energy storage modules 11 via their associated switches 12 before combining the modulated individual voltages. The modular battery storage system 10 has a neutral conductor 16 and an output 17, and in particular is able to supply a total voltage approximating a sinusoidal voltage to the source voltage via the output conductor 17.

[0099] The high clock frequencies required for PWM result in the corresponding high-frequency actuation 14 of the individual switches 12 generating electromagnetic interference radiation 15 in the area from the individual energy storage modules 11 and also in the area from the wires for actuation 14 of the switches 12. The high-speed switching action of the switches 12 generates strong alternating magnetic fields with large currents, making the modular battery storage system practically unusable. In this case, the structure of the modular battery storage system 10 not only interferes with its own operation due to electromagnetic interference radiation, but also radiates significant interference externally and may magnetically couple to adjacent conductors. This requires extensive shielding against electromagnetic interference radiation throughout the entire area of ​​the modular battery storage system 10. Furthermore, the output conductors 17 generate electromagnetic interference radiation 18, which must also be shielded.

[0100] FIG. 3 illustrates a modular battery storage system 100 according to the present invention. Furthermore, multiple energy storage modules 110 are provided, each with its own switch 120. The neutral conductor 160 shown in FIG. 3 is not required. Therefore, the system can also be designed as a three-phase system. In contrast to the conventional battery storage system described with reference to FIG. 2, a relatively simple circuit 120 is provided in both cases, which primarily switches the power supply of the individual energy storage modules 110 on and off and is controlled at a low frequency. Accordingly, the corresponding operation 140 by the control device 130 can be slow, for example, with a frequency of 100 Hz, corresponding to a half-wave clock of the power supply. For example, a simple 0 / 1 signal line is sufficient here. A data bus is not required, or a very simply designed communication bus can be provided. In particular, real-time-capable lines are not required. Due to the simple switches 120 and simple signal lines 140, there is no associated radiation of electromagnetic interference from the individual energy storage modules 110, and as a result, complex shielding measures can be omitted in this area.

[0101] The individual voltages U generated by the individual connection or operating energy storage modules 110 single , the total voltage U Total and feeds the central modulation unit 200 via output conductor 170. The core of the modulation unit 200 receives the total voltage U Total 1. The pulse width modulation switch 210 performs the pulse width modulation of the voltage curve required for fine tuning of the voltage curve. Downstream of the pulse width modulation switch 210 is a filter choke 220, which provides further smoothing of the total voltage that is cut off to some extent by the pulse width modulation.

[0102] The clock frequency for the pulse width modulation performed by direct control via drive line 230 of control device 130 is selected to be relatively high because filter choke 220 is then particularly effective and can therefore be designed to be relatively small. As filter choke 220 is typically the most expensive component of the entire battery storage system 100, this measure offers the potential for significant savings.

[0103] Electromagnetic interference radiation 280 generated in connection with high frequency pulse width modulation is effectively shielded by the housing 240 of the modulation unit 200, which housing 240 or modulation unit 200 is of particularly compact and robust design. In a particularly preferred embodiment, low pass filters 250, 260 are provided at the input and output of the modulation unit 200, respectively, to reduce the total voltage U Total may be further smoothed.

[0104] The total voltage U obtained after passing through the modulation unit 200 Total 171 is particularly suitable for being fed into an AC network, for example as one phase of three phases. The control device 130 is preferably an integral part of the modulation unit 200, since this also provides protection and shielding from the outside in a way that is particularly suitable for the control device 130. The pulse width modulation switch 210 may be controlled directly by the control device 130 via connection 230 , and a high speed data bus is not necessarily required for connection 230 .

[0105] Electromagnetic interference 280 caused by the high-frequency pulse width modulation switch 210 is reliably shielded by the housing 240. On the other hand, the compact and centralized design of the modulation unit 200, which also integrates the filter choke 220, allows for high switching frequencies and thus reduces the size and cost of the individual components. On the other hand, in the battery storage system 100 according to the invention, the space-occupying structure of the individual energy storage modules 110 can be formed without additional shielding measures, further reducing costs and simplifying the housing structure in the surrounding area of ​​the battery storage system. In a preferred embodiment, the modulation unit 200 includes a cooling device not further illustrated here.

[0106] 4 illustrates the basic power electronics architecture of the modulation unit 200. The pulse width modulation switch 210 includes an H-bridge circuit with two wire branches, each with two semiconductor switches (T1, T2 and T3, T4) connected (C_L) via a capacitor (212). The total voltage U from the energy storage module is Total (not shown here) is supplied to the input of the switch structure via output conductor 170. In this example, the total voltage U Total has the form of a step voltage 1.

[0107] The voltage applied to the capacitor 212 is regulated or controlled by driving the power semiconductors 211, in particular by pulse width modulation. After passing through the circuit 210 and the downstream filter reactor 220 (L_f), a smoothed sinusoidal voltage waveform 2 results, which can be supplied to the mains voltage, for example as one phase of three. However, this sinusoidal shape of the resulting voltage is only one possible example of a voltage that can be generated with the modular battery storage system according to the invention. Similarly, other waveforms or even direct current can be generated.

Claims

1. A modular battery storage system (100) having an array of n rechargeable energy storage modules (110), a. each of the n energy storage modules (110) includes at least one (preferably several) rechargeable energy storage element; and b. each individual one of the n energy storage modules (110) is assigned a switch (120) capable of activating and deactivating the respective energy storage module (110); and c. The n energy storage modules (110) operate at individual voltages U ｓｉｎｇｌｅ The total voltage U Ｔｏｔａｌ and d. The battery storage system (100) includes a control device (130) that controls the switches (120) associated with the n energy storage modules (110). It has the following characteristics: e. The battery storage system (100) comprises: i. The modulation unit (200) modulates the total voltage U Ｔｏｔａｌ connected to the n interconnectable energy storage modules (110) in such a way that the n energy storage modules (110) can modulate ii. The modulation unit (200) includes a pulse width modulation switch (210); and iii. The modulation unit (200) includes a housing (240) adapted to enclose the pulse width modulation switch (210) and shield electronic components outside the housing from electromagnetic interference radiation (280) emanating from the pulse width modulation switch (210). The modulation unit (200) includes: A modular battery storage system (100).

2. a. the pulse width modulation switch (210) includes a plurality of semiconductor switches (211); b. The pulse width modulation switch (210) includes an H-bridge circuit having four semiconductor switches (211); c. The pulse width modulation switch (210) includes an H-bridge circuit having four semiconductor switches (211), and the H-bridge circuit includes two wire branches each having two semiconductor switches (T1, T2 and T3, T4) connected via a capacitor (212).

10. The modular battery storage system of claim 1, having at least one of the following additional features:

3. a. The modulation unit (200) includes a filter choke (220) connected downstream of the pulse width modulation switch (210) in the discharge direction; b. The housing (240) further encloses the filter choke (220).

3. A modular battery storage system according to claim 1 or 2, having at least one of the following additional features:

4. a. the modulation unit (200) includes a low-pass filter (250) connected upstream of the pulse width modulation switch (210) in the discharge direction; b) the modulation unit (200) includes a low-pass filter (260) connected downstream of the pulse width modulation switch (210) in the discharge direction; c. The modulation unit (200) includes a low-pass filter (250) upstream or downstream of the pulse width modulation switch (210) in the discharge direction, and the housing (240) further encloses the low-pass filter (250) and / or the low-pass filter (260).

4. A modular battery storage system according to any one of claims 1 to 3, having at least one of the following additional features:

5. a. The housing is made of metal and / or metallized plastic A modular battery storage system according to any one of claims 1 to 4, with the additional feature that:

6. a. the modulation unit (200) includes a cooling device; b. A cooling device is assigned to said modulation unit (200) 6. A modular battery storage system according to any one of claims 1 to 5, having any one of the following additional features:

7. a. the switches (120) associated with the n energy storage modules (110) are not set up for pulse width modulation; b. The n energy storage modules (110) have no passive cooling devices or only one passive cooling device, or the n energy storage modules (110) have no passive cooling devices associated with the n energy storage modules (110) or only one passive cooling device associated with the n energy storage modules (110).

7. A modular battery storage system according to any one of claims 1 to 6, having at least one of the following additional features:

8. a. Signal lines (140) are provided to control the switches (120) associated with the n energy storage modules (110). A modular battery storage system according to any one of claims 1 to 7, with the additional feature that:

9. a. The control device (130) controls the time-varying total voltage U Ｔｏｔａｌ and configured to operate at least two of the energy storage modules (110) for different lengths of operation via their associated switches (120) that overlap in time to generate (t). A modular battery storage system according to any one of claims 1 to 8, with the additional feature that:

10. a. The control device (130) is configured to control the pulse width modulation switch (210) in the modulation unit (200). A modular battery storage system according to any one of claims 1 to 9, with the additional feature that:

11. a. the control device (130) is a signal processor; b. The control device (130) is a microcontroller 11. A modular battery storage system according to any one of claims 1 to 10, having any one of the following additional features:

12. A method of operating a modular battery storage system (100) according to any one of claims 1 to 11, comprising: a. generating a stepped voltage (1) by successively activating and deactivating n energy storage modules (110); b. feeding said stepped voltage (1) to a modulation unit (200) of said modular battery storage system (100) and converting it into a smoothed sinusoidal voltage (2) by pulse width modulation and at least one filtering; A method comprising:

13. a. Feed the smoothed sinusoidal voltage (2) into an AC power grid as a phase The method of claim 12 having the additional feature:

14. a. Driving the energy storage modules (110) of the modular battery storage system (100) at a frequency between 50 Hz and 500 Hz, particularly 100 Hz.

14. The method according to claim 12 or 13, having the additional feature:

15. a. Driving the pulse width modulation switch (210) of the modulation unit (200) at a high frequency in the range of 1 kHz to 1 Mhz. The method according to any one of claims 12 to 14, having the additional feature that:

Images