Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
  • H02J1/08—Three-wire systems; Systems having more than three wires
  • H02J1/082—Plural DC voltage, e.g. DC supply voltage with at least two different DC voltage levels
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
  • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
  • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
  • H01M10/4264—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing with capacitors
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
  • H02J7/0014—Circuits for equalisation of charge between batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
  • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
  • H01M2010/4271—Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2220/00—Batteries for particular applications
  • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J2310/00—The network for supplying or distributing electric power characterised by its spatial reach or by the load
  • H02J2310/40—The network being an on-board power network, i.e. within a vehicle
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/60—Other road transportation technologies with climate change mitigation effect
  • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

Definitions

• the invention relates to a battery system for a motor vehicle, which has a first battery module, which has a first voltage source, a first inductance, a positive pole and a negative pole, a second battery module, which has a second voltage source, a second inductance, a positive pole and a has negative pole, an output capacitor which has a positive terminal and a negative terminal, a first switching unit assigned to the first battery module for electrically connecting the first battery module to the output capacitor, and a second switching unit assigned to the second battery module for electrically connecting the second battery module to the Includes output capacitor.
• the invention also relates to a method for operating a battery system according to the invention and to a motor vehicle that has a corresponding battery system.
• Conventional motor vehicles have a drive which usually comprises an internal combustion engine. Furthermore, conventional motor vehicles include a battery system for supplying a starter and other consumers of the motor vehicle with electrical energy and a generator for charging the battery system. Electric vehicles have a battery system for supplying a traction motor and other consumers with electrical energy.
• a generic battery system of a conventional motor vehicle comprises at least two battery modules with at least one, preferably with several battery cells, which are for example connected in series.
• Such a battery module has a nominal voltage of 12 V, 24 V or 48 V, for example.
• An output voltage of a battery system of a conventional motor vehicle corresponds to the nominal voltage of the battery modules, which are connected in parallel.
• a generic battery system of an electric vehicle can also have a higher output voltage of 600 V, for example.
• a generic battery system also includes an output capacitor, which is used to buffer the output voltage of the battery system. Such an output capacitor is electrically connected to an on-board network of the motor vehicle and is also referred to as an intermediate circuit capacitor.
• a generic battery system also comprises at least two switching units for electrically connecting the battery modules to the output capacitor. By means of the switching units, the battery modules can be electrically connected to the on-board network of the motor vehicle and to the output capacitor, as well as being separated from the on-board network and the output capacitor.
• the battery cells of the battery modules are, for example, lithium-ion battery cells.
• the discharge of the battery cells of the battery modules does not necessarily take place evenly.
• the charges of the battery cells, and thus also the charges of the battery modules, can therefore differ from one another, and the voltages of the battery modules are then not all at the same level.
• the charge states of the battery modules must be at least approximately the same. Therefore, the charge states of the individual battery modules are regularly adjusted. Such an adjustment is also referred to as balancing.
• the document EP 2 575 246 A1 discloses a DC voltage converter with a high-voltage side and a low-voltage side, as well as a method for discharging a capacitor on the high-voltage side by means of a transformer.
• Document US 2019/058430 A1 discloses a device which has an electric motor, two voltage sources and a plurality of converters for controlling the electric motor.
• a hybrid drive train system which has a high-voltage battery and contains a DC coupling which is coupled to a rectifier / inverter module.
• the rectifier / inverter module is electrically connected to two torque machines and includes a switch device which includes a pair of power transistors.
• WO 2017/064820 A1 discloses a system for generating electrical energy which comprises a generator, a frequency converter and an energy conversion system.
• a battery system for a motor vehicle comprises a first battery module, which has a first voltage source, a first inductance, a positive pole and a negative pole, a second battery module, which has a second voltage source, a second inductance, a positive pole and a negative pole, an output capacitor , which has a positive terminal and a negative terminal, a first switching unit assigned to the first battery module for electrically connecting the first battery module to the output capacitor and a second switching unit assigned to the second battery module for electrically connecting the second battery module to the output capacitor.
• the battery modules each include a plurality of battery cells that can be connected to one another both in series and in parallel within the battery modules.
• the battery cells are preferably designed as lithium ion battery cells.
• the battery cells simulate electrical cell voltage sources.
• Electrical lines within the battery modules have inductances.
• the electrical cell voltage sources of the battery cells of a battery module each form the voltage source of the respective battery module.
• the inductance of the electrical lines of a battery module forms the inductance of the respective battery module.
• the battery modules can also have a coil with an additional inductance.
• Said output capacitor is, for example, an intermediate circuit capacitor.
• the intermediate circuit capacitor can be electrically connected to an on-board network of the motor vehicle and serves to buffer a Output voltage of the battery system.
• the battery module can also have a further capacitor.
• each of the switching units has a first switching element, a second switching element and a third switching element.
• the switching elements each have three connections, a switching path being formed between a first connection and a second connection, which can be controlled by means of a third connection.
• the switching units are preferably constructed identically and connected in the same way to the respectively assigned battery module and to the output capacitor.
• a first connection of the first switching element is connected to a junction, and a second connection of the first switching element is connected to one of the poles of the assigned battery module.
• a first connection of the second switching element is connected to the node, and a second connection of the second switching element is connected to one of the terminals of the output capacitor.
• a first connection of the third switching element is connected to the other of the poles of the associated battery module and to the other of the terminals of the output capacitor, and a second connection of the third switching element is connected to the junction.
• the second connection of the first switching element is connected to the positive pole of the associated battery module, and the second connection of the second switching element is connected to the positive terminal of the output capacitor.
• the first connection of the third switching element is then connected to the negative pole of the assigned battery module and to the negative terminal of the output capacitor.
• the negative pole of the battery module is permanently connected to the negative terminal of the output capacitor.
• each of the two battery modules can be electrically connected to the on-board network of the motor vehicle and to the output capacitor, as well as being disconnected from the on-board network and the output capacitor.
• the first switching element and the second switching element are closed and the third switching element is open, so the respective battery module is connected to the vehicle electrical system and to the output capacitor. If both battery modules are connected to the vehicle electrical system and to the output capacitor, they are connected in parallel.
• the battery system can also comprise more than two battery modules, each with an assigned switching unit.
• the first switching element, the second switching element and the third switching element of the switching units are each designed as field effect transistors and each have a SOURCE connection, a DRAIN connection and a GATE connection.
• the switching elements are connected in such a way that the first connection is the SOURCE connection, the second connection is the DRAIN connection and the third connection is the GATE connection.
• the switching elements are MOSFETs, in particular n-channel MOSFETs of the enhancement type.
• the first switching element, the second switching element and the third switching element of the two switching units each have a switching path and an inverse diode connected in parallel to the switching path, which is also referred to as a body diode.
• a method for operating a battery system according to the invention is also proposed.
• the second switching unit is activated in such a way that a current flows through the second battery module, whereby electrical energy is transmitted to the second voltage source of the second battery module.
• the current flows through the second switching unit, through the second inductance and through the second voltage source, among other things.
• the battery cells of the second battery module are charged. This increases the state of charge of the second battery module and the voltage of the second voltage source of the second battery module increases. If the state of charge of the second battery module is lower than the state of charge of the first battery module, then the method according to the invention brings about an equalization of the charge states, that is, a balancing of the two battery modules.
• the electrical energy that is transmitted to the second voltage source of the second battery module is preferably taken from the first battery module and / or the output capacitor and is transmitted to the second voltage source of the second battery module by said current.
• the state of charge of the first battery module drops at the same time. This further accelerates the equalization of the charge states, i.e. the balancing of the two battery modules.
• the second switching unit is preferably activated in several successive phases.
• the second switching unit is controlled in such a way that, during a first phase, electrical energy is transmitted from the first battery module to the second inductance of the second battery module, and during a second phase, electrical energy is transmitted from the second inductance of the second battery module to the second voltage source of the second battery module is transmitted.
• the second switching unit is preferably controlled in such a way that, during a first phase, the first switching element of the second switching unit is closed, the second switching element of the second switching unit is closed and the third switching element of the second switching unit is opened.
• the current flows through the first switching element, through the second switching element, through the second inductance and through the second voltage source.
• the second switching unit is preferably further controlled in such a way that, during a second phase, the first switching element of the second switching unit is closed, the second switching element of the second switching unit is opened and the third switching element of the second switching unit is closed.
• the current flows through the first switching element, through the third switching element, through the second inductance and through the second voltage source.
• the second switching unit is also preferably controlled in such a way that the first phase and the second phase are repeated cyclically.
• the first phase and the second phase are preferably repeated at a relatively high frequency of, for example, 20 kHz.
• a motor vehicle which comprises at least one battery system according to the invention, which is operated with the method according to the invention.
• the battery system according to the invention can be operated in a manner similar to a DC / DC converter, or like a buck converter.
• electrical energy is transmitted in particular from the first voltage source to the internal inductances and on to the second voltage source.
• the voltage of the second voltage source always remains less than or equal to the voltage of the first voltage source.
• Figure 1 is a schematic representation of a battery system
• FIG. 2 shows a schematic representation of the battery system during a first phase of the method
• FIG. 3 shows a schematic representation of the battery system during a second phase of the method.
• FIG. 1 shows a schematic representation of a battery system 10 for a motor vehicle.
• the battery system 10 comprises a first battery module 5, a second battery module 6, an output capacitor CA, a first switching unit 50 assigned to the first battery module 5, and a second switching unit 60 assigned to the second battery module 6.
• the first switching unit 50 is used to electrically connect the first battery module 5 with the output capacitor CA.
• the second switching unit 60 serves to electrically connect the second battery module 6 to the output capacitor CA.
• the battery modules 5, 6 each include a plurality of battery cells, not shown here, which can be connected to one another both in series and in parallel within the respective battery module 5, 6. Each of the battery cells simulates an electrical cell voltage source.
• the electrical cell voltage sources of the battery cells each form a voltage source VI, V2 of the respective battery module 5, 6.
• Inductances of electrical lines of the battery modules 5, 6 form inductances LI, L2. Additional coils with an additional inductance can optionally be provided.
• the inductances of the electrical lines together with the inductances of the coils form the inductances LI, L2.
• the first battery module 5 thus has the first voltage source VI and the first inductance LI.
• the first battery module 5 also has a positive pole 22 and a negative pole 21. When idling, a voltage supplied by the first voltage source VI is applied between the positive pole 22 and the negative pole 21.
• the second battery module 6 thus has the second voltage source V2 and the second inductance L2.
• the second battery module 6 also has a positive pole 22 and a negative pole 21. When idling, a voltage supplied by the second voltage source V2 is applied between the positive pole 22 and the negative pole 21.
• the output capacitor CA has a positive terminal 12 and a negative terminal 11.
• the output capacitor CA is, for example, an intermediate circuit capacitor which is electrically connected to an on-board network of the motor vehicle.
• the battery modules 5, 6 can have further capacitors, which together with the intermediate circuit capacitor then form the output capacitor CA.
• the first switching unit 50 and the second switching unit 60 are constructed identically in the present case.
• the switching units 50, 60 each have a first switching element 61, a second switching element 62 and a third switching element 63.
• the switching elements 61, 62, 63 each have three connections, a switching path being formed between a first connection and a second connection, which can be controlled by means of a third connection.
• the switching units 50, 60 each have an internal node 25.
• the first switching element 61, the second switching element 62 and the third switching element 63 are in the present case designed as field effect transistors.
• the switching elements 61, 62, 63 each have a SOURCE connection, a DRAIN connection and a GATE connection.
• the switching elements 61, 62, 63 are connected in such a way that the first connection is the SOURCE connection, the second connection is the DRAIN connection and the third connection is the GATE connection.
• the switching elements 61, 62, 63 are in the present case n-channel MOSFETs of the enhancement type.
• the switching elements 61, 62, 63 each have a switching path and an inverse diode connected in parallel to the switching path.
• the inverse diode which is also referred to as a body diode, is created in every MOSFET due to its internal structure and is not an explicit component.
• the first connection of the first switching element 61 is connected to the node 25.
• a second connection of the first switching element 61 is connected to the positive pole 22 of the associated battery module 5, 6.
• a first connection of the second switching element 62 is connected to the node 25.
• a second terminal of the second switching element 62 is connected to the positive terminal 12 of the output capacitor CA.
• a first connection of the third switching element 63 is connected to the negative pole 21 of the associated battery module 5, 6 and to the negative terminal 11 of the output capacitor CA.
• a second connection of the third switching element 63 is connected to the node 25.
• FIG. 2 shows a schematic illustration of the battery system 10 during a first phase of the method.
• the first switching element 61 in the first switching unit 50 is closed, the second switching element 62 is closed and the third switching element 63 is opened.
• the first switching element 61 in the second switching unit 60 is closed, the second switching element 62 is closed and the third switching element 63 is opened.
• a current I flows during the first phase through the second voltage source V2, through the second inductance L2, as well as through the first switching element 61 and through the second switching element 62 of the second switching unit 60.
• the current I also flows through the first voltage source during the first phase VI, through the first inductance LI, as well as through the first switching element 61 and through the second switching element 62 of the first switching unit 50.
• Electrical energy is transmitted from the first voltage source VI to the first inductance LI and to the second inductance L2.
• the state of charge of the first battery module 5 drops in the process.
• the second switching element 62 of the second switching unit 60 is opened and the third switching element 63 of the second switching unit 60 is closed.
• a second phase begins.
• the first switching element 61 of the second switching unit 60 remains closed.
• the first switching element 61 and the second switching element 62 of the first switching unit 50 remain closed, and the third switching element 63 of the first switching unit 50 remains open.
• FIG. 3 shows a schematic representation of the battery system 10 during the second phase of the method.
• the first switching element 61 in the first switching unit 50 is closed, the second switching element 62 is closed and the third switching element 63 is opened.
• the first switching element 61 in the second switching unit 60 is closed, the second switching element 62 is opened and the third switching element 63 is closed.
• a current I flows during the second phase through the second voltage source V2, through the second inductance L2, as well as through the first switching element 61 and through the third switching element 63 of the second switching unit 60. Electrical energy is thereby transferred from the second inductance L2 to the second voltage source V2 of the second battery module 6 is transmitted. The state of charge of the second battery module 6 increases in the process.
• the third switching element 63 of the second switching unit 60 can also remain open during the second phase.
• the third switching element 63 is designed as a MOSFET and has an inverse diode, which is also referred to as a body diode.
• the third switching element 63 is arranged in the second switching unit 60 in such a way that the current I flowing during the second phase can flow through the said inverse diode.
• the second switching element 62 of the second switching unit 60 is closed and the third switching element 63 of the second switching unit 60 is opened.
• Another first phase begins.
• the first switching element 61 of the second switching unit 60 remains closed.
• the first switching element 61 and the second switching element 62 of the first switching unit 50 remain closed, and the third switching element 63 of the first switching unit 50 remains open.

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Citations (5)

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• 2019
  • 2019-08-19 DE DE102019212351.1A patent/DE102019212351A1/de active Pending
• 2020
  • 2020-07-28 WO PCT/EP2020/071196 patent/WO2021032411A1/de unknown
  • 2020-07-28 EP EP20747391.9A patent/EP4018520A1/de active Pending
  • 2020-07-28 CN CN202080058389.9A patent/CN114270594A/zh active Pending
  • 2020-08-17 TW TW109127909A patent/TW202110032A/zh unknown

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