WO2011070078A2

WO2011070078A2 - System for decentrally storing and generating electric energy

Info

Publication number: WO2011070078A2
Application number: PCT/EP2010/069186
Authority: WO
Inventors: Joachim Fetzer; Stefan Butzmann; Holger Fink
Original assignee: Sb Limotive Company Ltd.; Sb Limotive Germany Gmbh
Priority date: 2009-12-10
Filing date: 2010-12-08
Publication date: 2011-06-16
Also published as: WO2011070078A3; EP2510601A2; EP2510601B1; EP2510601B2; DE102009054485A1

Abstract

The invention relates to a battery system, comprising a plurality of battery modules, each having one or more battery cells, a direct voltage intermediate circuit having a first pole and a second pole, and a converter connected between the direct voltage intermediate circuit and a connection for an energy supplier network, said converter being designed to convert an alternating voltage of the energy supplier network into a direct voltage and to output it to the direct voltage intermediate circuit, and to convert a direct voltage of the direct voltage intermediate circuit into an alternating voltage and to output it to the energy supplier network. Each battery module has a DC/DC converter and the modules are connected to the direct voltage intermediate circuit by means of the respective DC/DC converter.

Description

description

title

System for decentralized storage and generation of electrical energy

State of the art

There is a growing demand for battery systems which are to be used in stationary applications such as wind turbines and emergency power systems. In the near future, the energy supply of households will become increasingly decentralized, that is, there will be increasingly in the households energy converters such. Solar cells or fuel cells used to generate electrical energy on site. In addition, there is an interest on the part of the energy supply companies, in phases of low grid load electrical energy caching and in peak load times both to cover the total energy demand, as well as to support the network again. It would be advantageous to be able to perform the storage also decentralized to relieve the network in the peak load times, since the energy to be retrieved is already stored in close proximity to the consumer. For the decentralized storage of electrical energy, however, there are currently no suitable concepts available.

DISCLOSURE OF THE INVENTION The object of the invention is to introduce a device which fulfills the abovementioned

Needs to satisfy.

The invention therefore leads to a battery system having a plurality of battery modules, each comprising a multiplicity of battery cells, a direct voltage intermediate circuit having a first pole and a second pole, and a connection between the DC voltage intermediate circuit and a connection to an energy source. power converter switched inverter, which is adapted to convert an AC voltage in the power supply network into a DC voltage and output to the DC intermediate circuit, and to convert a DC voltage in the DC voltage intermediate circuit in an AC voltage and output to the power supplier network, a. According to the invention, the battery modules each have a DC / DC converter, via which they are connected to the DC voltage intermediate circuit.

The battery cells of the battery system according to the invention are not directly coupled to the power supply network via the DC link and the inverter (rectifier / inverter). Instead, the battery system is made up of individual battery modules, each equipped with a DC / DC converter. The DC / DC converters are electrically connected on the primary side to the battery cells of the respective battery module.

On the secondary side, the DC / DC converters couple the battery modules to the DC link. This approach has a number of advantages:

High flexibility with regard to the design and possibly also the extension of the battery system. Components such as the inverter or even the individual battery modules can be standardized, a battery system can be adapted to current requirements due to the modular design and extended by adding further battery modules.

Increased reliability, as the failure of individual battery cells or battery modules does not lead to the failure of the entire battery system. Instead, the total energy to be taken from the battery system can be taken from the still properly functioning battery modules by adjusting the output voltage of the DC / DC converters accordingly or increasing the output power of the DC / DC converters.

High availability, since the battery system can continue to be operated with suitable design during the replacement of a battery module. The battery system can be constructed so that a battery module is electrically neutralized on the output side and the remaining battery modules perform the memory tasks. With a suitable mechanical design, the battery module to be replaced can be removed from the battery system and replaced by another, which is then activated, so that all the battery modules of the battery system are active again. Easy and safe maintainability of the battery system, as the individual battery modules each have a voltage which is below the permissible contact protection limits (eg a voltage of a battery module can be 60V, so that no danger to the maintenance personnel is to be expected).

Increased life of the battery system, since the battery modules can be involved depending on their aging state, their state of charge, their temperature and possibly also other parameters in the storage and delivery of electrical energy to varying degrees (eg, the performance during the charging and Discharging the battery or the state of charge change of the battery modules), so that the battery modules are subject to uniform aging. The battery modules can be operated differently due to the topology of the battery system. Thus, an influence on an operating strategy is ready, e.g. the aging state of the battery modules with a view to the most uniform aging possible. However, it is also possible to optimize other parameters in operation via the operating strategy, e.g. the state of charge of the battery modules, with a view to the same value as possible for all battery modules.

Increased system performance by using different battery cells (e.g., power and power cells) to optimize the battery system for required operations. So battery modules can be used with different electrical properties. By way of example, battery modules with battery cells (energy cells) optimized for storing the largest possible quantities of electrical energy can be mixed with those having the largest possible electrical output (power cells), the mixing ratio being determined primarily by the requirements for the maximum power to be delivered.

Cost-effective implementation of the overall system, since the inverter can be designed for a constant DC link voltage and a separate charging and disconnecting device for charging the DC link can be omitted. In battery-based emergency generators according to the prior art, the intermediate circuit voltage is dependent on the state of charge of the directly coupled to the DC voltage intermediate battery cells dependent and thus changeable, which is avoided by the DC / DC converter of the invention.

For the battery system is without additional effort a short circuit protection and a limitation of the occurring during the charging and discharging currents and power available, since the DC / DC converter can be controlled or disabled accordingly. The plurality of battery modules may include a first battery module and a second battery module, wherein the first battery module includes a first DC / DC converter and the second battery module includes a second DC / DC converter.

In a preferred embodiment, the first DC / DC converter is connected in series with the second DC / DC converter on the output side. In this case, a first output of the first DC / DC converter may be connected to the first pole of the DC intermediate circuit and a second output of the first DC / DC converter to a first output of the second DC / DC converter. These embodiments make it possible to generate a high DC link voltage by summing the output voltages of the individual DC / DC converters. If a battery module is to be deactivated (for example, for replacement), the associated DC / DC converter is deactivated and an alternative path for the battery current in the battery system is closed. The battery module is so electrically neutralized and can be removed from the battery system. The DC / DC converters of the remaining battery modules can then be adjusted so that they compensate for the reduced by the removal of the battery module to be replaced DC link voltage by generating a correspondingly higher voltage.

Alternatively, the first DC / DC converter can be connected in parallel with the second DC / DC converter on the output side. This embodiment has the advantage that battery modules can be removed or added without any readjustment and without any circuit measures. The disadvantage, however, is that compared with the voltage of the battery cells in the battery modules high output voltage of the DC / DC converter, which corresponds to a pure parallel connection of the DC link voltage, a lower efficiency of the DC / DC converter has the consequence. It is therefore also conceivable hybrid forms, in which a plurality of groups of output side series-connected battery modules or DC / DC converters are in turn connected in parallel.

Preferably, the DC voltage intermediate circuit for connecting a wind turbine, a photovoltaic system, a generator or fuel cell designed to allow seamless integration into other existing electrical energy systems.

The battery cells are preferably designed as lithium-ion battery cells or as nickel-metal-hydride battery cells, which have the advantages of a long service life (more than 2,500 complete charge and discharge cycles), low self-discharge and high efficiency.

The inverter may have a line filter which reduces the load on the power supply network with harmonics due to the functioning of the system

Reducing the inverter helps.

Preferably, the connection to the power supply network are designed in three phases and the converter is designed to convert an AC voltage in the three-phase E- nergieversorgernetz in a DC voltage and output to the DC voltage intermediate circuit, and to convert a DC voltage in the DC voltage intermediate circuit in an AC voltage and output to the three-phase power supply network. In this case, the electrical energy taken or supplied to the three-phase power supply network is distributed as evenly as possible over the three phases of the power supply network.

The battery system may have a buffer capacitor which has a first electrode connected to the first pole of the DC intermediate circuit and a second electrode connected to the second pole of the DC intermediate circuit.

drawings

Brief description of the pictures

The invention is explained in more detail below with reference to illustrations of exemplary embodiments. Show it:

Fig. 1 shows a battery system according to the invention;

Fig. 2 shows a first embodiment of the invention; and Fig. 3 shows a second embodiment of the invention.

Detailed description of the pictures

Fig. 1 shows a battery system according to the invention. A battery 10, the internal structure of which is explained in more detail with reference to FIGS. 2 and 3, serves as an energy store of the battery system of the invention. The battery 10 is connected to a first pole 1 1 a and a second pole 1 1 b of a DC intermediate circuit, which connects the battery 10 with a converter 12. In the example shown, the DC intermediate circuit has an optional buffer capacitor 18, which stabilizes the DC voltage in the DC intermediate circuit. The inverter 12 is used for the energy transfer between the DC voltage intermediate circuit and the power supply network with which the inverter via

Connections 13 is connected. The inverter can convert an AC voltage of the power supply network into a DC voltage and output to the DC intermediate circuit (charging the battery 10), or convert the DC voltage of the DC intermediate circuit into an AC voltage and output to the power supplier network (discharge of the battery 10). The inverter 12 may additionally include terminals 14 for the connection of a household or other electrical consumers. The DC link can also be connected to other electrical energy sources that generate DC voltages, such as DC voltages. to a wind turbine 15, a photovoltaic system 16 or a fuel cell 17. Of course, other DC generators can be connected, for example, driven by an internal combustion engine. In this case, if necessary, power-electronic measures should be provided in order to enable connection to the DC intermediate circuit, e.g. in the form of DC / DC converters in order to be able to adapt to the voltage in the DC intermediate circuit. It may possibly also on the circuit concepts for the internal organization of the battery 10, as will be explained with reference to FIGS. 2 and 3, are applied.

With the architecture shown in FIG. 1, at least the following operating states can be realized: The household is fed from the energy supply network. Energy is stored in the battery 10. The possibly existing additional electrical energy sources do not emit energy into the DC voltage intermediate circuit.

The household is fed from the energy supply network. The other household electrical energy sources emit energy stored in the battery 10.

The household is fed from the energy supply network. The additional electrical energy sources do not emit energy, the battery 10 is charged from the power grid (e.g., at times of low network load).

The household is fed from the energy supply network. The additional electrical energy sources emit energy which is fed into the energy supply network via the converter. In addition, the battery 10 may be charged or discharged. This can result in a positive or negative energy balance, i. the power grid is effectively taken or supplied energy.

In case of failure of the power grid, the household can be powered by the inverter from the battery 10 and / or the additional electrical energy sources. Also in this operating condition, if necessary, the battery 10 can be charged if more electrical energy is generated on site than is consumed in the household.

The system architecture illustrated in FIG. 1 thus offers the possibility of exchanging electrical energy between the energy supply network, the battery 10 and possibly additional energy sources.

In Fig. 1, the connection of the battery system and the power supplier network is exemplified three-phase, but can be done without limiting the inventive idea even in a single-phase network. In order to be able to meet the requirements of the energy supply companies with regard to the permissible harmonic content in the mains currents, the use of a

Net filter makes sense, which can be inserted in the inverter. Fig. 2 shows a first embodiment of the invention. Components having the same reference numerals as in Fig. 1 correspond to those of Fig. 1, and therefore a description will be omitted. The battery 10 of the first embodiment of the invention has a plurality of battery modules 19-1 to 19-n, each containing one or more, usually series-connected, battery cells. The battery modules 19-1 to 19-n are connected on the output side to a respective DC / DC converter 20-1 to 20-n. The DC / DC converters 20-1 to 20-n, in turn, are connected on the output side to a series circuit, so that each output of a DC / DC converter is connected to an output of an adjacent DC / DC converter. The first DC / DC converter 20-1 of the series circuit has an output which is connected to the first pole 1 1 a of the DC intermediate circuit. Accordingly, the last DC / DC converter 20-n of the series circuit has an output which is connected to the second pole 1 1 b of the DC intermediate circuit.

Fig. 3 shows a second embodiment of the invention. Again, identical reference numerals denote corresponding components as in FIGS. 1 and 2. However, the battery 10 of the second embodiment deviates in its internal structure from that of the first embodiment. Here, the outputs of the DC / DC converters 20-1 to 20-n are connected in parallel, i. Each of the DC / DC converter 20-1 to 20-n has a first output which is connected to the first pole 1 1 a of the DC intermediate circuit, and a second output which is connected to the second pole 1 1 b of the DC intermediate circuit ,

Claims

claims

1 . A battery system having a plurality of battery modules (19-1, ..., 19-n), each comprising one or more battery cells, a DC voltage intermediate circuit having a first pole (1 1 a) and a second pole (1 1 b), and one between the DC voltage intermediate circuit and a

Connection (13) for an energy supplier switched inverter (12), which is designed to convert an AC voltage of the power supply network into a DC voltage and output to the DC link, as well as to convert a DC voltage of the Gleichspannungszwi- schenkreises in an AC voltage and output to the power supplier network, characterized in that the battery modules (19-1, ..., 19-n) each have a DC / DC converter (20-1, ..., 20-n) and have in each case a DC / DC converter ( 20-1 20-n) are connected to the DC intermediate circuit.

2. The battery system of claim 1, wherein the plurality of battery modules (19-1, ..., 19-n) comprises a first battery module (19-1) and a second battery module (19-2, 19-n), wherein the first battery module (19-1) comprises a first DC / DC converter (20-1) and the second battery module (19-2, 19-n) comprises a second DC / DC converter (20-2, 20-n ).

The battery system of claim 2, wherein the first DC / DC converter (20-1) is connected in series with the second DC / DC converter (20-2, 20-n) on the output side.

4. The battery system of claim 3, wherein a first output of the first DC / DC converter (20-1) is connected to the first pole (11a) of the DC intermediate circuit and a second output of the first DC / DC converter (20-1). 1) are connected to a first output of the second DC / DC converter (20-2, 20-n).

The battery system of claim 2, wherein the first DC / DC converter (20-1) is connected in parallel with the second DC / DC converter (20-2, 20-n) on the output side.

6. The battery system of one of the preceding claims, wherein the DC voltage intermediate circuit for connecting a wind turbine (15), a photovoltaic system (16), a generator or fuel cell (17) is formed.

7. The battery system of one of the preceding claims, wherein the battery cells are designed as lithium-ion battery cells or as nickel-metal hydride battery cells.

The battery system of any one of the preceding claims, wherein the inverter (12) has a mains filter.

9. The battery system of one of the preceding claims, wherein the terminal (13) to the power grid three-phase executed and the inverter (12) is adapted to convert an AC voltage in the three-phase power supply network into a DC voltage and to the

Output DC voltage intermediate circuit, and to convert a DC voltage in the DC voltage intermediate circuit in an AC voltage and output to the three-phase power supply network.

10. The battery system of one of the preceding claims with a

Buffer capacitor (18) which has a first electrode connected to the first pole (1 1 a) of the DC intermediate circuit and a second electrode connected to the second pole (1 1 b) of the DC intermediate circuit.