WO2014206838A1

WO2014206838A1 - Method for connecting a plurality of battery units to a two-pole input of a bidirectional battery converter, and also bidirectional battery converter and photovoltaic inverter

Info

Publication number: WO2014206838A1
Application number: PCT/EP2014/062856
Authority: WO
Inventors: Aleksandra-Sasa BUKVIC-SCHÄFER; Florian Ellerkamp; Klaus Rigbers
Original assignee: Sma Solar Technology Ag
Priority date: 2013-06-28
Filing date: 2014-06-18
Publication date: 2014-12-31
Also published as: DE102014108601A1

Abstract

In order to connect a plurality of battery units (11 to 13) in parallel or in series to a two-pole input (8) of a bidirectional battery converter (9) which has measuring devices, the battery units are initially individually connected to the input. A relevant variable parameter of the individually connected battery units is detected by the measuring devices, and the relevant parameter of the individually connected battery units (11 to 13) is adjusted by the battery converter (9). Only the battery units (11 to 13) of which the relevant parameters have been adjusted are then jointly connected to the input (8) in order to operate said battery units with the battery converter (9) as a closed battery bank.

Description

METHOD FOR CONNECTING MULTIPLE BATTERY UNITS TO A BIPOLAR INPUT OF A BIDIRECTIONAL BATTERY TRANSFORMER AND BIDIRECTIONAL BATTERY TRANSFORMER AND PHOTOVOLT AIKWECHSELRICHTER

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for parallel or serial connection of multiple battery units to a two-pole input of a measuring devices having bidirectional battery converter comprising the steps of the preamble of independent claim 1. Furthermore, the present invention relates to a bidirectional battery converter for parallel or serial connection of multiple battery units with a two-pole input, with measuring means for at least one relevant parameter of the battery units connected to the input and with a controller having an operating mode for performing the method. In addition, the inventive method still refers to a photovoltaic inverter with such a battery converter.

STATE OF THE ART

From WO 02/39563 A1 a battery charging device and method for charging batteries by means of a power supply module are known. In this case, a battery comprises a plurality of series-connected battery blocks. The individual battery blocks of the battery are charged once per charge cycle in succession for a certain period of time, and the charging cycle is repeated until the individual battery blocks have reached a defined state of charge or the power supply is interrupted. The known battery charging device is provided in particular for charging batteries for electric vehicles. In one embodiment variant of the known method, switching over from one battery block to the next during a charging cycle takes place automatically by means of a changeover switch. The Switching can be done electronically and / or electronically controlled. In a further embodiment, the charging of a single battery block per charging cycle takes place during a period of 30 to 300 seconds. This has the advantage, inter alia, that in the event of premature termination of the charging, the battery blocks do not have too large charge differences.

From DE 10 2005 045 107 A1 a charging method for extending the life of batteries and a device for carrying it out are known. In the charging method, in addition to a main charging of a battery having at least two battery cells connected in series, auxiliary charging is performed. This includes the steps of selectively charging at least one selected battery cell beyond the normal state of charge of the battery and balancing the state of charge of the selected battery to the normal state of charge of the battery. It is therefore provided to extend the life of batteries to select a battery cell within a series connection of battery cells and then fully charged and then adjust the state of charge of these Selected lte battery cells again after charging the charge states of the other battery cells. Selective charging is done using an auxiliary load controller. The compensation of the state of charge is dissipative. In order to obtain an overview of the states of the battery cells and the total battery at all times, at least one battery parameter is constantly monitored. From DE 20 2006 003 587 U1 a battery charging compensation circuit with an electrical charging source is known. At least two batteries are connected in parallel with the electrical charging source. A PTC thermistor is provided as a defined current limiter, over which the connection of two positive poles of successive batteries is made. By means of the PTC thermistor an automatic battery charging with self-adjusting current limit is achieved in a simple manner. At the same time an overload of the electrical charging source is prevented.

DE 1 0 201 0 01 1 279 A1 discloses a method for compensating charge in a battery system and a battery system with a charge balancing circuit. The charge equalization takes place between two cells of a cell network of the battery system, which have a rest voltage. The charge balancing circuit charges a power latch in a first state. In a second state of the charge balance Circuit, the energy buffer stores one of the two cells with a charging voltage. This charging voltage is higher than either of the two resting voltages of the cells. In particular, the charge balance can be carried out between two cells of a cell network. That is, a first cell provides the energy that is transferred to the second cell. In particular, the charge balance can occur in connection with a voltage compensation.

From DE 10 2009 027 685 A1 a solar-supported battery charging device, in particular for a hybrid and / or electric vehicle, is known. The battery charging device has a drive device with a connection device for receiving a charging voltage supplied by a solar module. The driver selectively switches the charging voltage provided by the solar module to one or more of a high-voltage memory cell blocks divided into a plurality of cell blocks having a lower rated voltage than the entire high-voltage storage. A measuring device measures one or more parameters of the plurality of high-voltage memory cell blocks. A controller selectively switches the charging voltage supplied by the solar module to the one or more of the cell blocks based on the one or more measured parameters in accordance with a control logic implemented by the controller, to thereby connect the one or more cell blocks to the one or more cell blocks Charging voltage is switched through, selectively charging. Thus, the voltage of the solar module is at least the order of magnitude adapted to the charging voltage of the high-voltage storage to be charged.

From DE 197 36 414 A1 an electric motor vehicle is known in which a bidirectional up-divider is part of a battery circuit. One main contactor is turned off to disconnect one battery pack from another, switching contactors for connecting a first battery pack to a pair of bi-directional up-converter terminal pair and connecting a second battery pack to another pair of bi-directional up-converter terminal pairs. A recharge discharge of the first battery pack or an equalization charge of the second battery pack is performed by raising the output of the first battery pack and using that power to charge the second battery pack. The boost direction of the bidirectional step-up converter is changed to perform equalization charging of the first battery pack or refreshing discharge of the second battery pack. The lift direction is changed again to equalize the battery block charge states. This will be the Eliminates need for charging charger or recharging discharge charger.

From DE 10 201 1 089 312 A1 a system and a method for charging the energy storage cells of an energy storage device are known. The energy storage device comprises a plurality of parallel-connected power supply branches, each having a plurality of series-connected energy storage modules. In addition to at least one energy storage cell, each energy storage module comprises a coupling device which is designed to selectively switch or bypass the energy storage cell in the respective energy supply branch. A control device controls the coupling device in such a way that only so many energy storage modules in the respective power supply two-time battery charge current for the energy storage device are not exceeded in order to charge the energy storage cells. In this case, different states of charge of energy storage cells, which can occur, for example due to operation or aging, can already be compensated during the charging process, without the need for a cell-balancing process.

US 201 1/0140649 A1 discloses an energy storage system for charging and discharging a plurality of battery units. The battery units are connected via an equal Za h l bidirectional battery converter to a DC voltage link to which a variable-power source, such as a photovoltaic generator, via a DC / DC converter is connected. The DC link feeds an inverter connected to an AC grid. The battery units are connected via a switching device with the bidirectional battery converters. The switching device makes it possible to switch the battery units in whole or in part in parallel and to connect this parallel circuit with all or only part of the battery inverter. Likewise, a battery unit, for example in the event of a defect, can be switched off and replaced without impairing the function of the system using the other battery units.

OBJECT OF THE INVENTION

The invention has for its object to provide a method for parallel or serial connection of multiple battery units to a two-pole input of a measuring device. conditions exhibiting bidirectional battery converter, with the battery units, which initially have unknown states, can be connected in parallel or serially together to the input of the battery converter without great expenditure on equipment to operate them in a meaningful way as a closed battery bank. In addition, a corresponding battery converter and a photovoltaic inverter equipped with it are to be shown.

SOLUTION

The object of the invention is achieved by the method having the features of the independent patent claim 1 and by a battery converter with the features of the independent claim 13. The further independent claim 15 is directed to a photovoltaic inverter with such a battery converter. The dependent claims relate to preferred embodiments of the present invention.

DESCRIPTION OF THE INVENTION

In a method according to the invention for parallel or serial connection of a plurality of battery units to a bidirectional battery converter having a two-pole connection of a measuring device, the battery units are first connected individually to the input of the battery converter. This serves to detect at least one relevant variable parameter of each individual battery unit with the measuring devices of the battery converter and to match this relevant parameter of the individual battery units with the battery converter. Only after the relevant parameter of the individual battery units has been aligned with the battery converter in this way, the battery units are connected together to the input in order to operate it with the battery wall ler al as a closed battery bank.

In order to implement the method according to the invention, the battery converter does not need separate inputs for the individual battery units, but instead manages with a two-pole input. Accordingly, measuring devices for detecting the relevant parameter of the battery units must also be provided only at this two-pole input. As long as the battery units are individually connected to the two-pole input of the battery converter in the inventive method, measure the Measuring equipment in each case the relevant P ara m eter d he straight eand the connected battery unit. These measurements are used to determine the extent to which a change in the relevant parameter is required to match it to all battery units. This matching is done while only one battery unit is connected to the two-pole input of the battery converter. Only when the adjustment is completed, the battery units are connected in parallel or in series to connect them together with the two-pole input of the battery converter. Subsequently, they are operated via the battery converter as a single closed battery bank.

The method according to the invention is suitable for eliminating differences in the relevant parameters of the individual battery units with little expenditure on equipment, before the battery units are interconnected and connected to the battery converter for operation as a closed battery bank. When the battery units are to be connected in parallel, to avoid equalizing currents between the batteries, it is necessary to equalize their output voltages before interconnecting. On the other hand, if the battery units are to be serially connected to form a battery bank, it is important to keep equal charge levels so that the total energy stored in the battery bank is actually available. The matching of the values of the relevant parameter with the individual battery units according to the invention does not require that these values be exactly identical after matching. Rather, it is sufficient if they match a predefined tolerance of, for example, a few percent.

In the context of the method according to the invention, it is also possible to determine on the basis of the detected relevant parameter of the individual battery units whether they are at all suitable for parallel or serial connection to a closed battery bank, ie are compatible. If this is not the case, a corresponding signal must be output to prevent the batteries from being connected together. Furthermore, it is possible for the battery converter to refuse to operate the battery units, which are nevertheless connected together, as a closed battery bank until battery units which match one another are first connected individually to their input and successfully tested for compatibility. In the method according to the invention, the parameters of the individual battery units can be adjusted by means of power supply or removal from or into an AC network which is connected directly or indirectly to the battery wall on the output side. At least it would be the case here that at least one of the battery units, whose at least one relevant parameter is changed, is supplied with electric power via the battery converter from the AC mains and / or is discharged into the AC mains. Alternatively or additionally, a power supply can take place from or into a photovoltaic generator with which the battery converter is connected in common to a DC / AC converter, since it can be connected to the AC mains as soon as possible. However, the method according to the invention makes use in particular of the alternating current network as a combined power source and sink of virtually infinite capacity. A local energy storage - in addition to the battery unit currently connected to the battery unit - does not require the inventive method. But this includes z. B. not that the battery converter is designed as a DC / DC converter, the output side is connected directly to an input side DC voltage intermediate circuit of a DC / AC converter, which is then connected on the output side connected to the AC mains. In this case too, the matching of the relevant parameters of the battery units is not restricted by the storage capacity of the DC voltage intermediate circuit.

In one embodiment of the method according to the invention, the battery units are connected to the battery converter only once, in order to both capture their relevant parameters and to adjust the detected relevant parameters such that the relevant parameters of all battery units for the subsequent battery already exist Combining the battery units is suitable for the battery bank. However, this assumes that the value to which the relevant parameter is adjusted for all battery units is fixed from the outset. However, it often turns out to be advantageous to set the value to which the relevant parameter of all battery units is adjusted only after this parameter has been recorded for all battery units. In particular, the subsequent matching of the relevant parameter to the predetermined value can be done much faster if this predetermined value is at least at most most battery units already close to the detected value of the parameter. This is achieved by first connecting all battery units once to the two-pole input of the battery converter to detect their relevant parameters. Then, taking into account the detected values of the relevant parameter of the battery units, a value is set to which the relevant parameter of all battery units is to be adjusted. Subsequently, at least all the battery units whose relevant parameters must actually be changed due to differences still present, are connected once more to the two-pole input of the inverter. It goes without saying that in this procedure, the battery unit connected last to the input for capturing the relevant parameter does not have to be temporarily suspended before its relevant parameter is adjusted if necessary.

When setting the value of the relevant parameter to which the relevant parameter of all battery units is adjusted, various criteria can be taken into account. One of these criteria is to minimize the duration of the procedure. That is, the value of the relevant parameter is set so that adjusting the parameter of the individual battery units to this value as a whole is as fast as possible. This criterion is certainly not relevant. Since, in addition to or instead of the food, it is possible to operate a minimization of the individual connection processes at the input of the battery converter during the method according to the invention. If, for example, two or more battery units have values of the relevant parameter that are close to each other or within a tolerance to be complied with, it may be useful to adapt all other battery units with their relevant parameter to these values by the number of connection processes at the two-pole input of the battery converter to minimize. Another criterion that can be taken into account when determining the values for the relevant parameter is minimizing energy losses through the process. On the one hand, this can be about absolute energy losses, which can be described by power losses. On the other hand, it can also be a matter of avoiding the accumulation of amounts of energy which are fed into an AC network connected on the output side to the battery converter and which are not or only badly tempered and in so far represent a loss.

Another criterion may be a minimization of the supply of energy from the AC network to which the battery wall is connected on the output side and / or of electrical energy provided by a generator which together with the battery converter An AC mains is connected. Then, the values of the relevant parameter at least substantially by discharging individual battery units adapted to each other. Yet another criterion may be to maximize self-consumption of electrical energy provided by a generator, such as a photovoltaic generator, which may be connected to an AC grid together with the battery converter. In this case, the self-consumption of such decentrally generated electrical energy is to be understood as meaning that it is consumed locally at the place of its generation and thus, in particular, without loading of a superordinate alternating current network. This is done by local consumers connected to the generator and the battery converter before a grid connection point.

It is also possible to take into account the different criteria with different or different weightings when determining the values of the relevant parameter to which the relevant parameters of all battery units are adjusted ,

As already indicated, the output voltages can be detected as a relevant parameter for parallel connection of the battery units to a battery bank. Optionally, the aging status of the battery units can additionally be detected. Then the output voltage has to be adjusted to each other. In some types of batteries, such as, for example, certain lead-acid batteries, the aging state of the individual battery units can also be changed by means of special charging and / or discharging processes known per se, and thus matched to one another.

For serial connection of the battery units to a battery bank, the state of charge and additionally the aging state of the battery units can be detected. Then then at least the state of charge and possibly also the aging state of the individual battery units to be matched to each other.

In the method according to the invention, the individual connection of the battery units to the two-pole input of the battery converter can be carried out manually. This can be connected individually by a control of the battery converter z. B. be instructed via a display.

In principle, the individual connection of the battery units to the input can also take place via a separate multiplexer device, ie via a multiplexer device, which is provided especially for carrying out the method according to the invention, but no part of the Battery converter, which is still present when the battery units are connected together as a battery bank and connected to the input of the inverter.

If one of the battery units which have been connected to the battery converter according to the method according to the invention fails and has to be replaced by a new battery unit, it may be sufficient to connect the new battery unit individually to the input of the battery converter, the at least one relevant parameter of the new one To detect battery unit and to adjust the value of the at least one relevant parameter of the other old battery units. Thereafter, the new battery unit can then be connected directly to the housing with the old battery units in order to operate it with the battery converter as a closed battery bank. This procedure assumes that the value of the at least one relevant parameter of the other old battery units is known from their previous operation. Otherwise it must at least be detected using one of the other old battery units.

A bidirectional battery converter according to the invention, to which a plurality of battery units can be connected in parallel or serially, comprises a two-pole input, measuring means for at least one relevant parameter of the battery units connected to the input and a controller which has a selectable operating mode for carrying out the invention Has method. From a known bidirectional battery converter, the battery converter according to the invention thus differs essentially by the selectable operating mode of its control.

The battery converter can be a DC / DC converter, which is connected to a photovoltaic generator in a DC / AC converter, wherein the DC / AC converter can be connected on the output side to an AC network. The photovoltaic generator can be connected directly or, for example, via a further DC / DC converter together with the battery converter to a DC voltage intermediate circuit of the DC / AC converter.

In principle, however, the battery converter can itself also be a DC / AC converter, which can be connected directly to an AC network on the output side. A photovoltaic inverter according to the invention has, in addition to a battery converter according to the invention, which is designed as a DC / DC converter, a further input for connecting a photovoltaic generator and a DC / AC Wa urn a, wherein the battery converter together with the further input to a DC voltage intermediate circuit of the DC / AC converter is connected. In such a photovoltaic changer, the battery bank formed from the battery units which can be connected to the battery converter on the input side serves as a buffer for electrical energy which is generated with the photovoltaic generator only during the day and even then not exactly when it is needed locally , The battery wall and the battery bank can thus be used, in particular, to maximize the self-consumption of the energy generated decentrally with the photovoltaic generator.

Advantageous developments of the invention will become apparent from the claims, the description and the drawings. The advantages of features and of combinations of several features mentioned in the description are merely exemplary and can take effect alternatively or cumulatively, without the advantages having to be achieved by embodiments according to the invention. Without altering the subject matter of the appended claims, as regards the disclosure of the original application documents and the patent, the following applies: Further features can be found in the drawings. The combination of features of different embodiments of the invention or of features of different claims is also possible deviating from the chosen relationships of the claims and is hereby stimulated. This also applies to those features which are shown in separate drawings or are mentioned in their description. These features can also be combined with features of different claims. Likewise, in the claims listed features for further embodiments of the invention can be omitted.

The features mentioned in the patent claims and the description are to be understood in terms of their number that exactly this number or a greater number than the said number is present, without requiring an explicit use of the adverb "at least". For example, when talking about an element, it should be understood that there is exactly one element, two elements or more elements. These features may be supplemented by other features or be the only characteristics that make up the product in question. The reference signs contained in the patent claims do not limit the scope of the objects protected by the claims. They are for the sole purpose of making the claims easier to understand.

BRIEF DESCRIPTION OF THE FIGURES

In the following the invention will be further explained and described by means of embodiments with reference to the accompanying drawings.

Fig. 1 shows a photovoltaic inverter, the input side to a on a

Photovoltaic generator and on the other hand connected to a battery bank of three series-connected battery units and the output side to an AC power supply.

Fig. 2 shows a photovoltaic generator, which corresponds to Fig. 1, except that the battery bank is composed of three battery units connected in parallel.

Fig. 3 illustrates, as in a method according to the invention, the battery units of

Battery bank are first individually connected to a two-pole input of the photovoltaic inverter of FIG. 1 or 2.

4 is a flowchart of an embodiment of the present invention

process; and

FIG. 5 illustrates a routine that may occur in two steps of the method of FIG. 4.

DESCRIPTION OF THE FIGURES

The illustrated in Fig. 1 photovoltaic inverter 1 has a DC / AC converter 2, which is connected on the output side to an AC network 3. The DC / AC converter 2 feeds electrical energy into the AC network 3. This electrical energy can come from a photovoltaic generator 4, which is connected to an input 1 9. Alternatively, it comes from a battery bank 5, these two energy sources both individually and can also be active together. The photovoltaic generator 4 is connected via the input 19 to a DC / DC converter 6, for example a step-up converter, which feeds the electrical energy of the photovoltaic generator 4 into a DC voltage intermediate circuit 7 and to this an output voltage L of the photovoltaic generator 4 to an intermediate circuit voltage UZWK of the DC intermediate circuit 7 high sets. The DC / DC converter is basically optional and can be omitted if the photovoltaic generator directly provides an output voltage L suitable as intermediate circuit voltage UZWK. The DC intermediate circuit 7 is the input intermediate circuit of the DC / AC converter 2; and the intermediate circuit voltage UZWK is tuned to a mains voltage UNetz of the AC mains 3. The battery bank 5 is connected to a two-pole input 8 of a battery converter 9. The battery converter 9 is a bidirectional DC / DC converter, which is also connected to the DC voltage intermediate circuit 7 on the output side and feeds it from the battery bank 5 or draws this electrical energy in order to store it in the battery bank 5. The battery converter 9 and the connected battery bank 5 are used to compensate swan ku ngen in the electrical Leistungsu ng of the photovoltaic generator 4 and in the consumption profile locally locally connected consumers. That is, the battery bank 5 is used with the battery converter 9 as a buffer for electric power from the photovoltaic generator 4, for example, to maximize self-consumption of that energy near the place of its generation. Dam it is z. B. even at times oh ne sufficient solar radiation and thus without sufficient power of the photovoltaic generator 4 possible to supply via the DC / AC converter 2 electrical energy in the AC network 3. Conversely, with an oversupply of electrical power of the photovoltaic generator 4, which exceeds the current consumption of the household, an intermediate storage in the battery bank 5 is possible. The stored electrical energy is then available for a later time, in which the power of the photovoltaic generator 4 is no longer sufficient. The battery bank 5 may also latch electrical energy from the AC grid 3, if the DC / AC inverter 2 is preferred, which is a bidirectional converter. The battery bank 5 comprises a plurality of battery units 1 1 to 13, which are connected in series in the embodiment according to FIG. 1, so that the voltage applied to the input 8 is the sum of the output voltages Uβatt of the individual battery units 1 1 to 13. Except for the interconnection of the battery units 1 1 to 13 to the battery bank 5, the photovoltaic inverter 1 according to FIG. 2 corresponds to that of FIG. 1. According to FIG. 2, the battery units 1 1 to 13 are connected in parallel, so that the voltage at the two-pole input 8 is equal to the output voltage Ußatt of each individual battery unit. So that there is no equalization currents between the batteries within the parallel connection of the battery units 11 to 13, which would be undamped, the output voltages Ußatt of the individual battery units 11 to 13 must be as equal as possible when they are connected together. In the case of the battery bank 5 according to FIG. 1, on the other hand, it is absolutely sensible that the states of charge, in particular in the form of the so-called state of charge (SOC), are as equal as possible in order to utilize as completely as possible the electrical energy stored in the battery bank 5 or its storage capacity to be able to. For the SOC, the battery voltage Ußatt is indeed an indication, but often not sufficient. Both in the series connection of the battery units 1 1 to 13 shown in FIG. 1 and in the parallel connection of the battery units 1 1 to 13 shown in FIG. 2 is a same aging state, often a State of H a lth (SO H) called net, all Battery units 1 1 to 13 also useful to use all battery units 1 1 to 13 evenly and completely.

In a method according to the invention, all relevant parameters of each individual battery unit are first detected by connecting each battery unit individually to the two-pole input 8 of the battery converter 9. For the battery unit 13, this is indicated in Fig. 3. Accordingly, the battery units 1 1 to 13 are not interconnected here to a battery bank. Directly when the battery units 1 1 to 13 are first connected to the input 8 for the first time or in another embodiment of the method for the second time, the relevant parameters of the battery units 1 1 to 13 are adapted to one another. For this purpose, electrical energy can be taken from the battery units 11 to 13 with the battery converter 9 or supplied to the battery units 11 to 13. In this case, there is no limitation due to the capacitance of the DC intermediate circuit 7, if the DC / AC converter 2 keeps the intermediate circuit voltage UZWK constant and, if necessary, also draws electrical energy from the AC network 3. When matching the relevant parameters of the battery units 1 1 to 13, the respective battery unit 1 1, 12 or 13, electrical energy from the photovoltaic generator 4 supplied or discharged from the respective battery unit 1 1, 12 or 13 in the AC mains 3. If it is not possible to match the relevant parameters, a corresponding warning signal can be output. 4 illustrates the entire sequence of the method according to the invention. In a first step 14, the battery units 1 1 to 13 are individually connected to the battery converter 9, and their relevant parameters are measured. The individual connection of the battery units 1 1 to 13 is typically carried out by the service technician who ultimately also combines the battery units 1 1 to 13 to the battery bank 5 and connects as such to the photovoltaic inverter 1. The measurement of the relevant parameters is carried out with measuring devices which the battery converter 9 anyway has to monitor the battery bank 5 normally connected to its input 8.

In the next step 15, suitable values for the relevant parameters of all battery units 1 1 to 13 are predefined on the basis of the values previously recorded for the relevant parameters. This can be done in particular by a control, i. H. a microprocessor happen, which is associated with the battery converter 9. In this case, the control can take into account certain predetermined criteria, such as a particularly fast process sequence or a minimization of electrical energy that has to be taken from the AC network 3.

In the following step 16, the battery units 1 1 to 13 are again individually connected to the input 8, this time to adjust their relative parameters to the predetermined values in step 15. Only then are all battery units 1 1 to 1 3 in the following step 17 joined together at the input 8 and then operated with the battery converter 9 as a closed battery bank 5.

The flowchart of FIG. 5 illustrates a routine with which one of the steps 14 and 16 according to FIG. 4 can be executed. After the start, a run variable i is first set to 0 and then increased by 1 at the beginning of a loop 18. Subsequently, the display that the battery unit corresponding to the state of the running variable i is connected individually (to the input 8) and this is to be confirmed (then). Once the confirmation is present, the relevant parameters of the respective battery unit are detected in step 14 or adjusted in step 15, the relevant parameters of the respective battery unit to the predetermined values. Subsequently, it is checked whether the running variable i has already reached the total number n of the battery units; if so, the routine ends, if not, the loop 18 is started again. It should be understood that the controller implementing the routine of FIG. 5 may also execute supplemental control subroutines, such as checking whether the each correct battery unit was connected. This is possible, at least in the context of step 16, after the relevant parameters of the individual battery units have first been detected in step 14. But even in step 14 can be checked that not accidentally, for example, the same battery unit instead of all the different battery units is connected individually to the input 8 of the battery converter 9.

LIST OF REFERENCE NUMBERS

1 photovoltaic inverter

2 DC / AC converters

3 AC mains

4 photovoltaic generator

5 battery bank

6 DC / DC converters

7 DC voltage intermediate circuit

8 entrance

9 battery converters

1 1 battery unit

12 battery unit

13 battery unit

14 step

15 step

16 step

17 step

18 loop

19 entrance

UPV output voltage of the photovoltaic generator 4

UZWK DC link voltage of the DC intermediate circuit 7

Un mains AC voltage of the AC mains 3

Ußatt output voltage of a battery unit 1 1, 12 or 13

i run variable

n Total number of battery units

Claims

1 . Method for parallel or serial connection of a plurality of battery units (1 1 to 13) to a two-pole input (8) of a bidirectional battery converter (9) having measuring devices, comprising:

- Detecting a relevant variable parameter of the individual battery units (1 1 to 13) with the measuring devices; and

- Matching of the relevant parameter of the individual battery units (1 1 to 13) with the battery converter (9);

characterized,

- That the battery units (1 1 to 13) for detecting and matching individually to the input (8) are connected; and

- That the battery units (1 1 to 1 3), only after the relevant parameter has been adjusted, are connected in common to the input (8) to operate with the battery converter (9) as a closed battery bank (5).

2. The method according to claim 1, characterized in that in at least one of the battery units (1 1 to 13), the relevant parameter is changed, electrical power via the battery converter (9) from an AC network (3), to which the battery converter (9 ) is connected on the output side, or from a photovoltaic generator (4), with which the battery converter (9) is connected in common to a DC / AC converter (2), supplied and / or electrical power via the battery converter (9) in the AC network ( 3) is discharged.

3. The method according to claim 1 or 2, characterized in that the battery units (1 1 to 13) are first connected individually to the input (8) to detect their relevant parameters, and then at least the battery units ( 1 1 to 13) are connected a second time individually to the input (8) whose relevant parameter is changed to match with the battery converter (9).

4. The method according to any one of claims 1 to 2 bi 3, characterized in that the at least one relevant parameter of the battery units (1 1 to 1 3) to a value is adjusted in dependence on the previously detected values of the at least one relevant parameter.

5. Verfa h ren according to claim 4, characterized in that the value u nter consideration of at least one predetermined criterion in dependence on the previously detected values of the at least one relevant parameter is predetermined.

6. The method according to claim 5, characterized in that the at least one criterion is selected from:

- a minimization of the duration of the procedure;

- Minimizing the individual connection operations to the input (8) during the process;

- minimizing energy losses through the process;

- Minimizing the supply of energy from an AC network (3) to which the battery converter (9) is connected on the output side, and / or electrical energy, which is provided by a generator, which together with the battery converter (9) to an AC network (3) is connected; and

- Maximizing the self-consumption of electrical energy, which is provided by a generator which is connected together with the battery converter (9) to an AC network (3).

7. The method according to any one of the preceding claims, characterized in that an error message is issued when at least one detected parameter of at least one battery unit (1 1 to 13) with at least one detected parameter of at least one other battery unit (1 1 to 13) is incompatible.

8. The method according to any one of claims 1 to 7, characterized in that for parallel connection of the battery units (1 1 to 13), the output voltage (Ußatt) and optionally the state of charge and / or the aging state of the battery units (1 1 to 13) are detected and at least the output voltage (Ußatt) is adjusted.

9. The method according to any one of claims 1 to 7, characterized in that for the serial connection of the battery units (1 1 to 13) of the state of charge and optionally the Output voltage (Ußatt) and / or the aging state of the battery units (1 1 to 13) are detected and at least the state of charge is adjusted.

10. The method according to any one of claims 1 to 9, characterized in that the individual connection of the battery units (1 1 to 1 3) to the input (8) manually under the guidance of a control of the battery converter (9).

1 1. Method according to one of claims 1 to 9, characterized in that the individual connection of the battery units (1 1 to 13) to the input (8) via a separate multiplexer device, which is controlled by a controller of the battery converter (9).

12. The method according to any one of claims 1 to 1 1, characterized in that when replacing an old battery unit (1 1 to 13) by a new battery unit (1 1 to 13), the new battery unit (1 1 to 13) individually to the input (8) that the at least one relevant parameter of the newer battery unit (1 1 to 13) is detected and adapted to the value of the at least one relevant parameter of the other old battery units (1 1 to 13), and then that the new battery unit (1 1 to 13) together with the other old battery units (1 1 to 13) to the input (8) is connected.

13. Bidirektionaler battery converter (9), to the input side a plurality of battery units (1 1 to 13) are connected in parallel or serially, with

- a bipolar input (8);

- Measuring devices for at least one relevant parameter of the connected to the input (8) battery units (1 1 to 13); and

a control that has a selectable operating mode for performing the method of any one of the preceding claims.

14, battery converter (9) according to claim 13, characterized in that the battery converter (9) is a DC / DC converter, which is connected together with a photovoltaic generator (4) to a DC voltage intermediate circuit of a DC / AC converter (2), which is connectable to an AC mains (3).

15. Photovoltaic inverter (1) with a battery converter (9) according to claim 14, with a further bipolar input (19) for a photovoltaic generator (4) and with a DC / AC converter (2) for output-side connection to an AC network (3), wherein the battery converter (9) is a DC / DC converter, which together with the photovoltaic generator (4) to a DC voltage intermediate circuit (7) of the DC / AC Converter (2) is connected.