DE102019204314A1 - Electrochemical energy storage system - Google Patents

Abstract

An electrochemical energy storage system comprising: a plurality of electrochemical energy storage units which can be electrically connected to primary connection terminals of the electrochemical energy storage system for providing a primary electrical voltage, the electrochemical energy storage units comprising a plurality of electrochemical energy storage cells electrically connected in series; a plurality of electronic switches which are electrically connected to the electrochemical energy storage units in such a way that the electrochemical energy storage units can be electrically connected to secondary connection poles of the electrochemical energy storage system for providing a secondary electrical voltage which is lower than the primary electrical voltage, wherein in each case only one of the electrochemical energy storage units can be electrically connected cyclically to the secondary connection poles of the electrochemical energy storage system by means of electronic switches.

Description

The invention is based on an electrochemical energy storage system, a method for operating the electrochemical energy storage system and a use of the electrochemical energy storage system according to the preamble of the independent claims.

State of the art

The pamphlet DE 10 2014 201 351 A1 discloses an on-board network for a motor vehicle, the on-board network having a low-voltage sub-network for at least one low-voltage consumer and a high-voltage sub-network for at least one high-voltage consumer and a starter generator, the high-voltage sub-network being connected to the low-voltage sub-network via a coupling unit, the on-board network having a battery that is set up is to generate the high voltage and feed it into the high-voltage subsystem, and which has at least two battery units with individual voltage taps that are routed to the coupling unit. It is provided that the coupling unit is set up to provide at least a first and a second operating state, wherein in the first operating state the high-voltage sub-network is fed from all battery units of the battery and the low-voltage sub-network is fed from a battery unit and in the second operating state the high-voltage sub-network is off a battery unit is fed and the low-voltage subsystem is fed from at least one battery unit.

The pamphlet DE 10 2014 201 344 A1 discloses an on-board network for a vehicle with a low-voltage sub-network for at least one low-voltage consumer and with a high-voltage sub-network for at least one high-voltage consumer and a starter-generator, the high-voltage sub-network having a battery that is set up to generate the high voltage and output it to the high-voltage sub-network and the at least has two battery units with individual voltage taps, the high-voltage sub-network being connected to the low-voltage sub-network via a coupling unit which is set up to draw energy from the high-voltage sub-network and supply it to the low-voltage sub-network. It is provided that the coupling unit is set up to selectively connect the battery units to the low-voltage subsystem.

To save CO2, many vehicles use 48 volt systems to support a vehicle's internal combustion engine and for energy recovery in overrun phases. These 48 volt systems consist of an electrical machine coupled to a drive train and a battery system with a nominal voltage of 48 volts. In (partially) autonomous vehicles, redundantly supplied sensors and actuators are required to ensure ASIL D-compliant functionality. This means that at least until a driver of the vehicle takes over control functions or until the (partially) autonomous vehicle is transferred to a safe area, it must be controllable even if a primary system fails. For this purpose, an additional DC voltage converter is often used, which builds up a redundant 12 volt supply from the 48 volt on-board network. This leads to a higher vehicle weight and higher integration costs. The DC / DC converter also takes up additional installation space and the vehicle is less efficient due to power losses from the DC / DC converter.

It is the object of the present invention to further improve the state of the art. This object is achieved by the features of the independent claims.

Disclosure of the invention

Advantages of the invention

The procedure according to the invention with the characterizing features of the independent claims has the advantage that the electrochemical energy storage system comprises a plurality of electrochemical energy storage units which can be electrically connected to primary connection poles of the electrochemical energy storage system for providing a primary electrical voltage, the electrochemical energy storage units having a plurality comprise of series-connected electrochemical energy storage cells.

Furthermore, the electrochemical energy storage system comprises a plurality of electronic switches which are electrically connected to the electrochemical energy storage units in such a way that the electrochemical energy storage units with secondary connection poles of the electrochemical Energy storage system for providing a secondary electrical voltage that is lower than the primary electrical voltage, can be electrically connected, with only one of the electrochemical energy storage units being able to be electrically connected cyclically to the secondary connection poles of the electrochemical energy storage system by means of electronic switches.

This creates a redundant power supply that does not require additional components such as a separate DC voltage converter. Since there is no DC / DC converter, there are no conversion losses, which increases the efficiency of the electrochemical energy storage system. Furthermore, integration and production costs are saved and the weight and the necessary installation space for the electrochemical energy storage system are significantly reduced compared to the prior art.

Further advantageous embodiments are the subject of the subclaims.

The electrochemical energy storage system further comprises at least one electrical capacitance, which is electrically connected to the secondary connection poles in order to stabilize the provided secondary electrical voltage.

The electrical capacitance, in particular a capacitor, stabilizes the secondary electrical voltage during switching operations of the electronic switches, which can lead, for example, to voltage drops at the secondary connection poles. A reliable power supply is thereby achieved.

The electrochemical energy storage units that can be electrically connected to the primary connection poles of the electrochemical energy storage system are each electrically connected to an electronic switch, and electrical connections between each two of the electrochemical energy storage units are electrically connected to two electronic switches.

Galvanic isolation is provided between the primary connection poles and the secondary connection poles of the electrochemical energy storage system. The secondary connection poles must have their own ground network and a galvanic separation must be ensured in the connection to the primary connection poles, since in electrically driven vehicles usually a negative pole of the primary connection pole is electrically connected to the ground of the vehicle and thus a negative pole of the secondary connection pole . In some switching states of the electronic switches, this otherwise leads to electrical short circuits across the electrochemical energy storage cells.

The electronic switches are advantageously semiconductor switches and include power transistors, MOSFETs and / or thyristors. These have particularly short switching times and low losses.

The voltage provided at the primary connection poles of the electrochemical energy storage system is essentially 48 volts. As a result, there is no need for safety expenditure for contact protection, while at the same time more energy can be recovered, for example through recuperation processes.

The voltage provided at the secondary connection poles of the electrochemical energy storage system is essentially 12 volts. In this way, for example, a redundant sensor and actuator network can be supplied on a 12 volt basis.

1. a) Schalten von elektronischen Schaltern für eine vorgegebene zeitliche Verweildauer zum Einstellen eines ersten Schaltzustands, bei dem durch elektrisches Verbinden einer der elektrochemischen Energiespeichereinheiten mit den sekundären Anschlusspolen des elektrochemischen Energiespeichersystems eine sekundäre elektrische Spannung bereitgestellt wird;
2. b) Schalten von elektronischen Schaltern zum Einstellen eines zweiten Schaltzustands, bei dem durch elektrisches Verbinden der mindestens einen elektrischen Kapazität mit den sekundären Anschlusspolen des elektrochemischen Energiespeichersystems die im Wesentlichen gleiche sekundäre elektrische Spannung bereitgestellt wird;
3. c) Zyklisches Wiederholen der Schritte mit abwechselnden elektrochemischen Energiespeichereinheiten des elektrochemischen Energiespeichersystems zum gleichmäßigen Entladen der elektrochemischen Energiespeichereinheiten.

The method according to the invention for operating an electrochemical energy storage system comprises the following steps:

1. a) switching electronic switches for a predetermined time period to set a first switching state in which a secondary electrical voltage is provided by electrically connecting one of the electrochemical energy storage units to the secondary connection poles of the electrochemical energy storage system;
2. b) Switching electronic switches for setting a second switching state in which, by electrically connecting the at least one electrical capacitance to the secondary Terminal poles of the electrochemical energy storage system the essentially the same secondary electrical voltage is provided;
3. c) Cyclically repeating the steps with alternating electrochemical energy storage units of the electrochemical energy storage system for evenly discharging the electrochemical energy storage units.

• d) Vorgeben der zeitlichen Verweildauer für den ersten Schaltzustand in Abhängigkeit eines durch die sekundären Anschlusspole fließenden elektrischen Stroms und/oder einer maximal entnehmbaren Ladung aus den elektrochemischen Energiespeichereinheiten.

The method for operating an electrochemical energy storage system further comprises the following steps:

• d) Presetting the time dwell time for the first switching state as a function of an electrical current flowing through the secondary connection poles and / or a maximum charge that can be drawn from the electrochemical energy storage units.

The electrochemical energy storage system according to the invention is advantageously used in: electrically driven vehicles including hybrid vehicles, in stationary electrical energy storage systems, in electrically operated hand tools, in portable devices for telecommunications or data processing and in household appliances.

Figure list

Exemplary embodiments of the invention are shown in the drawing and explained in more detail in the description below.

• 1 eine schematische Darstellung einer Ausführungsform des erfindungsgemäßen elektrochemischen Energiespeichersystems; und
• 2 eine schematische Darstellung einer Systemtopologie gemäß dem Stand der Technik;
• 3 eine schematische Darstellung einer Ausführungsform einer erfindungsgemäßen Systemtopologie.

Show it:

• 1 a schematic representation of an embodiment of the electrochemical energy storage system according to the invention; and
• 2 a schematic representation of a system topology according to the prior art;
• 3 a schematic representation of an embodiment of a system topology according to the invention.

Detailed description of the exemplary embodiments

The same reference symbols denote the same device components in all figures.

1 shows a schematic representation of an embodiment of the electrochemical energy storage system according to the invention 100 . The electrochemical energy storage system 100 comprises a plurality of electrochemical energy storage units 101 , 102 , 103 , 104 that have primary connection poles 115 (1) , 115 (2) of the electrochemical energy storage system 100 are electrically connectable, for example via a switch 118 . The primary connection pole 115 (2) is with a first ground connection 113 electrically connected. The electrochemical energy storage units 101 , 102 , 103 , 104 each comprise a multiplicity of electrochemical energy storage cells connected electrically in series 101 (a) , 101 (b) , 101 (c) , 104 (a) , 104 (b) , 104 (c) .

In the embodiment shown, the electrochemical energy storage system comprises 100 12 energy storage cells connected electrically in series 101 (a) , 101 (b) , 101 (c) , 104 (a) , 104 (b) , 104 (c) , for example lithium-ion battery cells. The energy storage cells 101 (a) , 101 (b) , 101 (c) , 104 (a) , 104 (b) , 104 (c) have an electrical voltage between 2.8 volts and 4.2 volts, depending on the state of charge and load. A series connection of 3 energy storage cells each 101 (a) , 101 (b) , 101 (c) , 104 (a) , 104 (b) , 104 (c) accordingly has an electrical voltage that is suitable for supplying a 12 volt network, for example for supplying a redundant sensor-actuator assembly.

Three adjacent energy storage cells each 101 (a) to 101 (c) , 102 (a) to 102 (c) , 103 (a) to 103 (c) or 104 (a) to 104 (c) are used to ensure the supply of the redundant sensor-actuator network. Since the redundant sensor-actuator assembly has to work permanently, the redundant supply cannot be made permanently from three energy storage cells, since otherwise these energy storage cells will be permanently discharged.

The energy storage cells 101 (a) , 101 (b) , 101 (c) , 102 (a) , 102 (b) , 102 (c) , 103 (a) , 103 (b) , 103 (c) 104 (a) , 104 (b) , 104 (c) however, are via primary connection poles 115 (1) , 115 (2) recharged, for example via a 48V network, but only to the extent that the remaining charge is electrically connected in series Energy storage cells can take charge. There is therefore an imbalance of electrical voltages in the electrochemical energy storage units 101 , 102 , 103 , 104 to the extent that a state of charge equalization circuit of the electrochemical energy storage system 100 is not classically designed.

Therefore, the electrochemical energy storage system includes 100 also a variety of electronic switches 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 associated with the electrochemical energy storage units 101 , 102 , 103 , 104 are electrically connected in the way that they are connected to the primary connection poles 115 (1) , 115 (2) electrically connectable electrochemical energy storage units 101 , 104 each with an electronic switch 105 , 112 are electrically connected and electrical connections between each two of the electrochemical energy storage units 101 , 102 or. 102 , 103 or. 103 , 104 with two electronic switches 106 , 107 or. 108 , 109 or. 110 , 111 are electrically connected.

The electrochemical energy storage units 101 , 102 , 103 , 104 are by means of the electronic switch 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 cyclically with secondary connection poles 116 (1) , 116 (2) of the electrochemical energy storage system 100 Can be electrically connected to provide a secondary electrical voltage. The connection poles 116 (1) and 116 (2) form a galvanically separated supply network 114 with plus and minus pole, that of the first connection poles 115 (1) and 115 (2) is galvanically isolated.

At the secondary connection pole 116 a circuit is to be provided during the switching of the electronic switch 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 to stabilize the provided secondary electrical voltage. This can for example be an electrical capacitance 117 Include those with the secondary connection pins 116 (1) , 116 (2) is electrically connected and an upstream inductance to limit the capacitance 117 electrical current flowing.

In order to provide a secondary electrical voltage that is lower than the primary electrical voltage, the electrochemical energy storage units 101 , 102 , 103 , 104 cyclically using the electronic switch 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 electrically switched on and off according to the following switching states. counter Switching status A. B. C. D. E. 105 Open Closed Open Open Open 106 Open Open Closed Open Open 107 Open Closed Open Open Open 108 Open Open Open Closed Open 109 Open Open Closed Open Open 110 Open Open Open Open Closed 111 Open Open Open Closed Open 12 volt supply from energy storage unit Only over electrical capacitance 117 101 102 103 104

A dwell time in the switching states B to E can with a constant electrical consumption from one to the secondary connection poles 116 (1) , 116 (2) connected sensor-actuator network are purely time-controlled and, for example, switched for the same length of time for each switching state B to E. In an alternative embodiment, the dwell time can be determined by the sensor / actuator assembly of the energy storage unit 101 , 102 , 103 , 104 can be calculated dynamically.

Furthermore, a maximum permissible deviation between the charge states of the Energy storage units 101 , 102 , 103 , 104 be taken into account. Requirements for a state of charge compensation to compensate for the different self-discharge of the energy storage cells 101 (a) , 101 (b) , 101 (c) , 104 (a) , 104 (b) , 104 (c) are advantageously reduced, since only within one energy storage unit 101 , 102 , 103 , 104 a different self-discharge has to be compensated. The state of charge equalization between the energy storage cells 101 (a) , 101 (b) , 101 (c) , 104 (a) , 104 (b) , 104 (c) the remaining energy storage units 101 , 102 , 103 , 104 takes place via the length of time spent in switching states B to E.

If, despite a failed 12 volt primary supply from an internal combustion engine of a vehicle, energy continues to be fed into the 48 volt network by means of the electrical machine, the capacity of the energy storage system is greater 100 In addition, energy is available for a redundant supply of the sensor-actuator network. As all energy storage cells 101 (a) , 101 (b) , 101 (c) , 104 (a) , 104 (b) , 104 (c) are continuously recharged, a change in the switching status can counteract a deviation in the charging status.

2 shows a schematic representation of a system topology 200 according to the state of the art. The system topology 200 includes an internal combustion engine 201 , an electric machine 202 , a power electronics 203 , a 48 volt energy storage 204 , a DC-DC converter 205 , one with the DC / DC converter 205 connected 12 volt energy storage 207 as well as primary sensors and actuators 208 , a redundant DC / DC converter 206 for supplying redundant sensors and actuators 209 as well as primary systems 210 , for example braking system, steering system and / or lighting system.

3 shows a schematic representation of an embodiment of a system topology according to the invention 300 . The system topology 300 includes an internal combustion engine 301 , an electric machine 302 , a power electronics 303 , a 48 volt energy storage 304 , a DC-DC converter 305 , one with the DC / DC converter 305 connected 12 volt energy storage 307 as well as primary sensors and actuators 308 . Using a redundant electronic circuit 306 can be connected to secondary connection poles of the energy storage system 304 a 12 volt voltage, galvanically separated from the vehicle ground, for redundant sensors and actuators 309 as well as primary systems 310 to be provided.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102014201351 A1 [0002]
• DE 102014201344 A1 [0003]

Claims (10)

An electrochemical energy storage system (100) comprising: a) A plurality of electrochemical energy storage units (101, 102, 103, 104) which can be electrically connected to primary connection poles (115 (1), 115 (2)) of the electrochemical energy storage system (100) for providing a primary electrical voltage, the electrochemical energy storage units (101, 102, 103, 104) a multiplicity of electrochemical energy storage cells (101 (a), 101 (b), 101 (c), 102 (a), 102 (b), 102 (c)) electrically connected in series , 103 (a), 103 (b), 103 (c), 104 (a), 104 (b), 104 (c)); b) A plurality of electronic switches (105, 106, 107, 108, 109, 110, 111, 112), which are electrically connected to the electrochemical energy storage units (101, 102, 103, 104) in such a way that the electrochemical energy storage units (101, 102, 103, 104) can be electrically connected to secondary connection poles (116 (1), 116 (2)) of the electrochemical energy storage system (100) for providing a secondary electrical voltage that is lower than the primary electrical voltage, wherein only one of the electrochemical energy storage units (101, 102, 103, 104) by means of electronic switches (105, 106, 107, 108, 109, 110, 111, 112) cyclically with the secondary connection poles (116 (1), 116 (2)) ) of the electrochemical energy storage system (100) are electrically connectable. Electrochemical energy storage system (100) according to one of the preceding claims, further comprising: c) At least one electrical capacitance (117) which is electrically connected to the secondary connection poles (116 (1), 116 (2)) in order to stabilize the provided secondary electrical voltage. Electrochemical energy storage system (100) according to one of the preceding claims, characterized in that the electrochemical energy storage units (101, 104) which can be electrically connected to the primary connection poles (115 (1), 115 (2) of the electrochemical energy storage system (100), each having an electronic switch (105, 112) are electrically connected and electrical connections between each two of the electrochemical energy storage units (101, 102, 103, 104) are electrically connected to two electronic switches (106, 107, 108, 109, 110, 111). Electrochemical energy storage system (100) according to one of the preceding claims, characterized in that a galvanic separation is provided between the primary connection poles (115 (1), 115 (2)) and the secondary connection poles (116 (1), 116 (2)) . Electrochemical energy storage system (100) according to one of the preceding claims, characterized in that the electronic switches (105, 106, 107, 108, 109, 110, 111, 112) are semiconductor switches and comprise power transistors, MOSFETs and / or thyristors. Electrochemical energy storage system (100) according to one of the preceding claims, characterized in that the electrical voltage provided at the primary connection poles (115 (1), 115 (2)) of the electrochemical energy storage system (100) is between 12 volts and 60 volts, in particular 48 volts , is. Electrochemical energy storage system (100) according to one of the preceding claims, characterized in that the electrical voltage provided at the secondary connection poles (116 (1), 116 (2)) of the electrochemical energy storage system (100) is between 9 volts and 16 volts, in particular 12 volts , is. Method for operating an electrochemical energy storage system (100) according to one of the Claims 1 to 7th , comprising the following steps: a) switching electronic switches (105, 106, 107, 108, 109, 110, 111, 112) for a predetermined time period for setting a first switching state (B, C, D, E) in which a secondary electrical voltage is provided by electrically connecting one of the electrochemical energy storage units (101, 102, 103, 104) to the secondary connection poles (116 (1), 116 (2)) of the electrochemical energy storage system (100); b) Switching electronic switches (105, 106, 107, 108, 109, 110, 111, 112) for setting a second switching state (A), in which by electrically connecting the at least one electrical capacitance (117) to the secondary connection poles ( 116 (1), 116 (2)) of the electrochemical energy storage system (100), essentially the same secondary electrical voltage is provided; c) Cyclic repetition of the steps with alternating electrochemical energy storage units (101, 102, 103, 104) of the electrochemical energy storage system (100) for uniformly discharging the electrochemical energy storage units (101, 102, 103, 104). Method for operating an electrochemical energy storage system (100) according to Claim 8 , further comprising the following steps: e) Specifying the time dwell time for the first switching state (B, C, D, E) as a function of an electrical current flowing through the secondary connection poles (116 (1), 116 (2)) and / or an electrical current maximum charge that can be drawn from the electrochemical energy storage units (101, 102, 103, 104). Use of an electrochemical energy storage system (100) according to one of the Claims 1 to 7th in electrically powered vehicles, including hybrid vehicles, in stationary electrical energy storage systems, in electrically operated hand tools, in portable devices for telecommunications or data processing and in household appliances.

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