Transfer device, method for operating a transfer device and vehicle

Abstract

A charging device for a battery, wherein the battery comprises a series connection of at least two battery cells (BT1,..., BT12), wherein a positive terminal of each odd-numbered battery cell (BT1, BT3, ..., BT11) and a negative terminal of each even-numbered battery cell (BT2, BT4, ..., BT12) of the series connection of all battery cells (BT1,..., BT12) or a first subset of these battery cells (BT1,..., BT12) can be connected to a first connecting line (BL1) via a switching element (S1,...,S12), wherein a positive terminal of each even-numbered battery cell (BT2, BT4, ..., BT12) and a negative terminal of each odd-numbered battery cell (BT1, BT3, ..., BT11) of the series connection of all battery cells (BT1,..., BT12) or the first subset of these battery cells (BT1,..., BT12) can be connected to a first connecting line (BL1) via a switching element (S1,...,S12) is connectable to a further connecting line (BL2), wherein the charging device (1) comprises at least one first charging branch (2) with at least one capacitive element, wherein a first terminal (A1) of the charging branch (2) is connectable to or connected with the first connecting line (BL1), wherein a further terminal (A2) of the charging branch (2) is connectable to or connected with the further connecting line (BL2), wherein a switching element (S1,..., S12) is formed by at least two anti-series connected transistor switches, wherein the charging device (1) comprises a driver circuit (5) with a driver voltage terminal (6) for each switching element (S1,..., S12), wherein a gate terminal of each transistor switch of a switching element (S1,..., S12) is connected to the driver voltage terminal (6) of the driver circuit (5) of the switching element (S1,..., S12) is connected, characterized in that the charging device (1) comprises a control unit (7) for controlling the driver circuits (5), wherein a supply voltage connection of the control unit (7) is connected to a negative terminal of the last battery cell (BT4, BT12) of the series connection of all battery cells (BT1,..., BT12) or of the first subset.

Description

The invention relates to a charge reversal device for a battery and to a method for operating such a charge reversal device. The invention further relates to a vehicle having such a transfer device.U.S. Pat. No. 10,446,880 B2 discloses a device for balancing a battery stack having two or more battery modules using a resonant circuit.DE 10 2010 029 015 A1 discloses a circuit for a battery which enables inductive cell balancing with reduced circuit complexity.U.S. Pat. No. 10,396,569 B2 discloses a system for battery cell balancing using an LC resonance.DE 10 2018 221 099 A1 discloses a charge reversal device for a battery, wherein a charge reversal branch comprises a series connection of at least one capacitive element and at least one inductive element.EP 3 076 516 A1 discloses a battery cell balancing system and method which transfers energy between one or more battery cells using LC resonance.US 2015 / 0340886 A1 relates to a balancing technology of a multi-battery cell, and more particularly, to a battery cell balancing circuit using LC series resonance, by which it is possible to improve the usage time of a battery cell by generally or individually controlling charge or discharge with respect to a multi-battery cell.US 2009 / 0140694 A1 relates to the charging and discharging of batteries and the balancing between charged and discharged batteries.GB 2 451 138 A relates to battery management, and more particularly to a method and apparatus for balancing the charge of a plurality of series connected cells forming a battery.US 2005 / 0206386 A1 relates to a circuit and an individual voltmeter, wherein the ends of a battery cell are sequentially connected in series with other battery cells to form a capacitor.US 2017 / 0093183 A1 relates generally to the field of power electronics, in particular to a device for compensating battery powers.From the document "Rager: single capacitor battery balancing. 26 April 2016. URL: https: / / www.eevblog.com / forum / renewable-energy / single-capacitor-battery-battery-battery-balancing / , archived in http: / / web.archive.org / web / 20190415122751 / https: / / www.eevblog.com / forum / renewableenergy / single-capacitor-battery-battery-balancing / on 15.04.2019, [retrieved on 17.02.2021], a battery balancing system is known.It is desirable to minimize complexity and cost for manufacturing the transfer device.The technical problem therefore arises of creating a recharging device for a battery, a method for operating such a recharging device, and a vehicle with such a recharging device, in which complexity, in particular a number of required components and their connections, and costs for production are minimized.The solution of the technical problem is achieved by the subject matters having the features of the independent claims. Further advantageous embodiments of the invention are evident from the dependent claims.A charge reversal device for a battery is proposed, wherein the battery comprises a series connection of at least two battery cells. The battery preferably comprises a series connection of more than two battery cells, in particular three, four, five, six, seven, eight or nine or more than nine battery cells. The series circuit can in this case comprise an odd number of battery cells or an even number of battery cells.The battery can in particular form a vehicle battery or a part of a vehicle battery. The vehicle battery may be, in particular, a traction battery that serves to provide energy for the operation of an electric machine for driving the vehicle.A positive pole of each odd battery cell and a negative pole of each even battery cell of the series circuit of all battery cells or of a first subset of these battery cells can be connected to a first connecting line via a switching element. A first subset can comprise a plurality of, but not all, battery cells of the battery, wherein the battery cells of the first subset are, however, battery cells connected in series.An odd battery cell herein denotes an odd-numbered battery cell, the odd-numbered battery cell indicating the placement of the battery cell in the order of the series-connected battery cells. In other words, the ordinal number serves to identify the location at which the battery cell is located within the series of series-connected battery cells. An odd battery cell is therefore, for example, the first battery cell of the series circuit, the third battery cell of the series circuit, the fifth battery cell of the series circuit, etc. Accordingly, an even battery cell denotes a battery cell having an even atomic number. A straight battery cell is, for example, the second battery cell of the series circuit, the fourth battery cell of the series circuit, the sixth battery cell of the series circuit, etc.It is possible that each positive pole of each odd battery cell and each negative pole of each even battery cell can be connected to the first connecting line via a respective switching element, wherein the switching elements are formed separately from one another. However, if a negative pole of an even battery cell is connected to a positive pole of an odd battery cell, these poles can be connectable to the first connecting line via a common switching element.Furthermore, a positive pole of each even battery cell and a negative pole of each odd battery cell of the series circuit of all battery cells or of the first subset of these battery cells can be connected via a switching element to a further connecting line, that is to say a second connecting line.It is possible that all positive poles of each even battery cell and all negative poles of each odd battery cell can be connected to the further connecting line via switching elements formed separately from one another. However, if a negative pole of an odd battery cell is connected to a positive pole of an even battery cell, these poles can be connectable to the further connecting line via a common switching element.The number of switching elements can thus be greater by one than the number of series-connected battery cells.In the sense of this invention, "connected" means that the elements connected to one another can be electrically connected, in particular directly connected. A direct connection may refer to a connection via an electrical connection element, e.g. a line, but not via an electrical or electronic component.The transfer device comprises the explained switching elements for connecting the poles of the battery cells to the corresponding connecting lines.Furthermore, the device comprises the explained connecting lines.Furthermore, the transfer device comprises at least one first transfer branch, which can also be referred to as a first transfer section. In this case, a first connection of the charge reversal branch can be connected or is connected to the first connecting line, in particular via exactly or at least one switching element. The connection can also be permanently connected to the first connecting line. Furthermore, a further connection of the charge reversal branch can be connected to the further connecting line, in particular via exactly one or at least one further switching element, or is connected, in particular permanently connected.The first and the further connecting line, which can also be referred to as second connecting line, are formed here as mutually different connecting lines.The first and the further connection of the transfer branch are connections of the transfer branch which are different from one another. The charge reversal branch can thus comprise a totality or an overall circuit of electrical or electronic components which is arranged between the first and the further connection of the charge reversal branch.It is possible that the first connection can be connected both to the first connecting line and to the further connecting line, in particular by means of a switching element, e.g. by means of a changeover switching element. However, the first terminal cannot be simultaneously connected to both the first and the further connection line. In other words, a first connection connectable to the first and further connecting line can be connected to the first connecting line, but not to the further connecting line, in a first state, and to the further connecting line, but not to the first connecting line, in a further state. As explained in more detail below, however, it is also possible in particular for the first connection to be connectable or connected to the first connecting line but not to the further connecting line. In other words, this can mean that the charge reversal device is configured such that no electrical connection can be established between the first terminal and the further connecting line.Accordingly, it is possible for the further connection to be connectable both to the first connecting line and to the further connecting line, in particular by means of a switching element, for example by means of a changeover switching element. However, the further connection cannot be simultaneously connected to both the first and the further connecting line. In other words, a further connection connectable to the first and further connecting line can be connected to the first connecting line, but not to the further connecting line, in a first state, and to the further connecting line, but not to the first connecting line, in a further state. As explained in more detail below, however, it is also possible in particular for the further connection to be connectable or connected to the further connecting line, but not to the first connecting line. In other words, this can mean that the charge reversal device is configured such that no electrical connection can be established between the first terminal and the further connecting line.Alternatively, it is possible for the first connecting line to be connectable to the first terminal as well as to the further terminal, in particular by means of a switching element, e.g. by means of a changeover switching element. However, the first connection line cannot be simultaneously connected to both the first and the further connection. In other words, the first connecting line which can be connected to the first and further connection can be connected to the first connection, but not to the further connection, in a first state, and to the further connection, but not to the first connection, in a further state.Accordingly, it is possible for the further connecting line to be connectable to the first terminal as well as to the further terminal, in particular by means of a switching element, e.g. by means of a changeover switching element. However, the further connecting line cannot be simultaneously connected to both the first and the further connection. In other words, the further connecting line which can be connected to the first and further connection can be connected to the first connection, but not to the further connection, in a first state, and to the further connection, but not to the first connection, in a further state.Furthermore, the charge reversal device comprises at least one first charge reversal branch having at least one capacitive element. Preferably, the charge reversal branch comprises a series connection of at least one capacitive element and at least one inductive element. The fact that the charge reversal branch comprises a component can mean that the charge reversal branch comprises, in addition to this component, also further electrical or electronic components. A capacitive element can be designed in particular as a capacitor. An inductive element can be designed in particular as a coil. The series connection of at least one capacitive and at least one inductive element forms an oscillating circuit.The capacitive element of the charge reversal branch can also be referred to as a charge reversal capacitor. This capacitive element serves as a buffer for electrical energy / charge during charge balancing. A process for the charge equalization between different battery cells can in this case comprise a discharging process and a charging process.Thus, it is possible, for example, in a discharging process to transport charge from one or more battery cell(s) into the capacitive element, in particular via a corresponding current flow. After termination of this transport, electrical energy / charge can then be transported in a charging process from the capacitive element of the charge reversal branch into one or more battery cell(s), in particular likewise via a corresponding current flow. In this case, a battery cell, from which electrical energy is transported in the discharging process into the capacitive element of the charge reversal branch, is preferably not part of the battery cells, into which electrical energy / charge is transported in the charging process from the capacitive element of the charge reversal branch. Preferably, all battery cells from which electrical energy / charge is transported in the discharging process into the capacitive element of the charge reversal branch are different from the battery cells into which electrical energy / charge is transported in the charging process from the capacitive element of the charge reversal branch.The presence of the inductive element in the charge reversal branch advantageously means that no undesirably high currents can occur during the discharging process or the charging process. This advantageously ensures operability of the transfer device in an improved manner.The transfer device can of course comprise at least one control device for controlling the switching elements, in particular for setting switching times of the switching elements. This control device can be designed as a computing device or can comprise such a device. A computing device can be designed in particular as a microcontroller or as an integrated circuit, for example as an FPGA.Furthermore, the transfer device can comprise an evaluation device. The evaluation device and the explained control device can be designed as a common device. The evaluation device can also be designed as a computing device or can comprise such a computing device. By means of the evaluation device, variables explained in more detail below can be evaluated.Furthermore, a switching element for connecting a pole of a battery cell to the first or the further connecting line is formed by at least two transistor switches connected in antiseries. In this case, a first transistor switch is connected to the pole of the battery cell and is connected to the further transistor switch via a connecting section. The further transistor switch is then connected to a connecting line.A transistor switch is preferably formed by a MOSFET, wherein a MOSFET can comprise an intrinsic diode which is arranged electrically in parallel with the conduction path between drain and source of the MOSFET.Alternatively, the transistor switch may also comprise an IGBT. If a transistor switch comprises an IGBT, then the transistor switch can comprise a freewheeling diode which is formed separately from the IGBT and is connected electrically in parallel with the conduction path between emitter and collector of the IGBT.Normally-off MOSFETs or IBGTs can preferably be used as transistor switches, further in particular so-called n-channel MOSFETs / IGBTs or p-channel MOSFETs / IGBTs. Alternatively, however, it is also possible to use normally-on MOSFETs / IGBTs which can also be designed in this case as n-channel MOSFETs / IGBTs or p-channel MOSFETs / IGBTs.Antiseries here can mean that the forward directions of the free-wheeling diodes of the two transistor switches are oriented opposite to one another. For example, the transistor switches can be connected in series with one another in such a way that the forward direction of a first transistor switch is oriented from the connection line toward the pole and the forward direction of a further transistor switch is oriented from the pole toward the connection line. Alternatively, the transistor switches can also be connected in series with one another in such a way that the forward direction of the first transistor switch is oriented from the pole toward the connecting line and the forward direction of the further transistor switch is oriented from the connecting line toward the pole.In the case that the transistor switches of the switching element are formed by MOSFETs, the switching element can comprise, for example, a first MOSFET whose drain terminal is connected to the pole of a battery cell. The source terminal of this first MOSFET can be connected to a source terminal of a further MOSFET of the switching element. The drain terminal of this further MOSFET can then be connected to the connecting line. A forward direction of the intrinsic diode formed in the MOSFET may be oriented from the source toward the drain.Furthermore, the transfer device comprises a driver circuit with a driver voltage connection for each switching element. This driving voltage terminal serves to provide the gate voltage for each transistor switch.Further, a gate terminal of each transistor switch of a switching element is connected to the driving voltage terminal of the driving circuit of the switching element, respectively. In other words, the gate terminals of all transistor switches of a switching element are connected to the same drive voltage terminal. Thus, all gate terminals are supplied with the same voltage, whereby all transistor switches of a switching element can be simultaneously switched on (i.e. switched on) or switched off (i.e. switched off).Further, a reference voltage terminal of the driving circuit may be connected to the connection portion of the two transistor switches.The driver circuit can be part of the transfer device.Further, the control device already explained may generate the control signals for controlling the operation of the driver circuit, in particular a control signal for generating a desired gate voltage by the driver circuit.The formation of a switching element by at least two transistor switches connected in antiseries advantageously results in a switching element formed in this way being able to conduct current in both directions, i.e. from a pole of a battery cell toward the connecting line and from the connecting line toward the pole, and also to block voltages in both of the directions mentioned, as a result of which a high operational reliability of the charge reversal device is obtained.Due to the connection of the gate terminal of each transistor switch to the drive voltage terminal of the drive circuit, it is further advantageous that a separate drive circuit does not have to be integrated into the charge reversal device for each transistor switch and its drive voltage terminal then has to be connected to the respective gate terminal. This advantageously results in a reduction in the complexity, in particular with respect to the components to be installed and their signal connection, and in the costs for producing the transfer device. The efficiency of the charge reversal device likewise increases, since only one driver circuit is used for operating two transistor switches.In a further embodiment, a supply voltage terminal of the driver circuit of a switching element, which is connected to a negative pole of a battery cell, is electrically connected to a positive pole of the battery cell. This advantageously results in a voltage supply of the driver circuit that is simple to produce in terms of circuitry, which additionally makes it possible to minimize electrical losses during operation of the driver circuit and thus likewise to increase the efficiency of the transfer device. Furthermore, this advantageously allows the risk of generating an overvoltage between gate and source terminals of a transistor switch of the switching element to be reduced. Furthermore, it is advantageously the result that the driver circuit is supplied with the lowest possible potential from a source, as a result of which electrical losses are advantageously minimized and the efficiency of the transfer device is increased.In a further embodiment, the voltage at the driver voltage connection is provided by means of a level converter. In this case, the driver circuit can be designed as a level converter or can comprise such a level converter. By means of the level converter, for example, a level at the supply voltage terminal of the driver circuit can be converted into a desired level. A discrete or integrated electronic circuit can be referred to as a level converter here, which adjusts signal levels, in particular voltage levels, to desired level ranges. This advantageously allows operating reliability of the charge reversal device to be increased, since it can be ensured that the gate voltage of a transistor switch does not exceed a maximum permissible value. The level converter can be, in particular, a unidirectional level converter. The design of a level converter is known to the person skilled in the art.According to the invention, the transfer device comprises a control device for controlling the driver circuits. This has already been explained above.Furthermore, according to the invention, a supply voltage connection of the control device is connected to a negative pole of the last battery cell of the series circuit of all battery cells or of the previously explained first subset of battery cells. The negative pole of the last battery cell has the lowest potential of all poles of the series circuit or of the first subset. This advantageously results in a further reduction in the complexity of the transfer device, in particular since an energy supply of the control device which is simple to produce in terms of circuitry is made possible.In a further embodiment, the positive pole of the first battery cell of the series circuit of all battery cells or of the first subset is connected via a first protective line to the first connecting line and via a second protective line to the further connecting line, wherein at least one diode is arranged in each protective line. The positive pole of the first battery cell has the highest potential of the series circuit or of the first subset.A line direction of the at least one diode, which is opposite to the reverse direction of the diode, is directed from the corresponding connecting line toward the positive pole.Thus, the first protective line is arranged electrically in parallel to the switching element which connects the positive pole of the first battery cell to the first connecting line.In this way, over-voltages at the transistor switches can be advantageously avoided, whereby operational reliability of the transfer device is increased.In a further embodiment, the negative pole of the last battery cell of the series circuit of all battery cells or of the first subset is connected via a third protective line to the first connecting line and via a fourth protective line to the further connecting line, wherein at least one diode is arranged in each protective line. The line direction of these diodes can be directed from the negative pole towards the corresponding connecting line. Thus, the third protection line may be arranged in parallel with the switching element connecting the negative pole of the last battery cell to the first connection line.This also advantageously increases the operational reliability of the transfer device.In particular, the resistive element can be formed as a separate element, for example as a resistance element. Furthermore, in particular, the resistive element is different from a line resistance of the charge reversal branch, in particular a parasitic resistance.In a further embodiment, the charge reversal branch comprises a series circuit of at least one capacitive element, at least one inductive element and at least one resistive element. The resistive element can be embodied in particular as a resistor. However, it is also possible for the charge reversal branch not to comprise or contain a resistive element. The charge reversal branch is preferably formed by the explained series connection.This advantageously results in the oscillation properties of the resonant circuit formed by the charge reversal branch being able to be adapted. In particular, the provision of a resistor enables the setting of an attenuation of such an oscillating circuit and thus of desired electrical properties of the oscillating circuit and thus of the charge reversal device.In a further embodiment, the charge reversal device comprises at least one means for detecting or determining a voltage across the capacitive element of a charge reversal branch and at least one means for detecting or determining a voltage across the inductive element of a charge reversal branch.The means for detection can be designed in particular as a voltage sensor. However, it goes without saying that the invention is not limited to voltage sensors for detecting or determining the voltage. Alternatively or cumulatively, further means known to the person skilled in the art for detecting or determining such a voltage can be used. The means for detecting or determining can be connected here with the evaluation device explained above with data and / or signals. This advantageously results in an improved control of switching elements of the transfer device being made possible, namely a control depending on the detected or determined voltage. This will be explained in more detail below.In a further embodiment, the transfer device comprises a further transfer branch. The further charge reversal branch comprises a series circuit of at least one capacitive element and at least one inductive element. It is also possible for the further charge reversal branch to comprise a series circuit of the at least one capacitive element, the at least one inductive element and at least one resistive element. The further charge reversal branch is preferably formed by one of the series connections mentioned. In other words, the further charge reversal branch is formed in accordance with the previously explained charge reversal branch.Furthermore, a first connection of the further charge reversal branch can be connected to a third connecting line, in particular via a switching element, or connected, in particular permanently connected. Furthermore, a further connection of the further charge reversal branch can be connected to a fourth connecting line, in particular via a switching element, or connected, in particular permanently connected.The third and fourth connection lines are formed as different connection lines from each other. Further, these connection lines are also different from the first and the second connection lines explained above. As already explained with regard to the first and the second connecting line, it may be possible that the first connection of the further charge reversal branch cannot be connected to the fourth connecting line. Likewise, the further connection of the further charge reversal branch cannot be connected to the third connecting line. These connections cannot also be connected to the first and the second connecting line.Furthermore, a positive pole of each odd battery cell and a negative pole of each even battery cell of all battery cells or of a further subset of these battery cells can be connected to the third connecting line via a switching element. The further subset of battery cells comprises a plurality of battery cells of the battery connected in series. However, the further subset of battery cells here comprises at least one battery cell which is not part of the first subset of battery cells explained above.Alternatively, it is possible that a positive pole of each odd battery cell and a negative pole of each even battery cell of a further battery can be connected to the third connecting line via a switching element.Furthermore, a positive pole of each even battery cell and a negative pole of each odd battery cell of all battery cells or of the further subset of these battery cells can be connected to the fourth connecting line via a switching element.Alternatively, it is possible that a positive pole of each even battery cell and a negative pole of each odd battery cell of the further battery can be connected to the fourth connecting line via a switching element.This advantageously results in charge compensation being able to take place via a plurality of capacitive elements. This in turn advantageously increases flexibility of the charge reversal and the possibility of using switching elements with a lower maximum voltage resistance. This in turn allows costs to be saved during the production of the transfer device. Furthermore, it is advantageously the result that a charge reversal can also take place between battery cells of different batteries.It is further possible that the first connecting line can be connected via a first changeover switching element to the first connection as well as to the further connection, and the further connecting line can be connected via a further changeover switching element to the first connection as well as to the further connection. It is further possible that the inductive connection elements have the same inductance and / or that an alternating switching element is formed as a series circuit of two transistor switches or comprises such a series circuit and / or that the alternating switching elements are each formed as half-branches of a bridge circuit or comprise these half-branches and / or that the capacitive element of the charge-reversal branch is formed as a polarized capacitor or comprises such a capacitor.A method for operating a transfer device according to one of the embodiments described in this disclosure is further proposed. In this case, a discharge state can be set, wherein in the discharge state a first subsection of the series circuit of all battery cells is connected to the charge reversal branch. In this discharge state, electrical energy / charge can be transported from the battery cell(s) into the at least one capacitive element of the charge reversal branch. This can also be referred to as a discharging process. The discharge state can be set, for example, by driving the transistor switches of the respective switching elements. In the discharge state, in particular at least one battery cell of the first subsection can be discharged.The first subsection of the series circuit of all battery cells comprises at least one, but preferably a plurality of, series-connected battery cell(s) of the series circuit of all battery cells, more preferably, however, not all battery cells of the series circuit. However, it is also possible for the first subsection to comprise exactly one battery cell.In a state of charge, a further subsection of the series connection of all battery cells is connected to the charge reversal branch. The further subsection of battery cells here comprises at least one, but preferably a plurality of, series-connected battery cell(s) of the series circuit of all battery cells. However, it is also possible for the further subsection to comprise exactly one battery cell.The first subsection preferably comprises more battery cells than the further subsection. This advantageously results in a charge equalization that is quick in time.In this state of charge, electrical energy / charge can be transported from the at least one capacitive element of the charge reversal branch into the battery cell(s) of the further subsection. This can also be referred to as a charging process. The state of charge can also be set, in particular by actuating corresponding switching elements. Furthermore, at least one battery cell of the first subsection is not part of the further subsection. Preferably, no battery cell of the further subsection is a battery cell of the first subsection (and vice versa). However, it is also possible that a plurality of battery cells, but not all battery cells, of the first subsection are not part of the further subsection.The discharge state and the charge state can be set here by the control device explained above. In particular, the discharge state can be set until the at least one capacitive element of the charge reversal branch has reached a predetermined state of charge, in particular until the charge state has increased to the predetermined state of charge, and / or until one or more battery cell(s) of the first subsection has reached a predetermined state of charge, in particular until the state of charge of this battery cell(s) has decreased to the predetermined state of charge.The state of charge can be set until one or more battery cells of the further subsection have each reached a predetermined (desired) state of charge, in particular until the state of charge of this battery cell(s) has increased to this predetermined state of charge, and / or until the state of charge of the at least one capacitive element has reached a predetermined threshold value, in particular until this state of charge has fallen to the predetermined threshold value.In this case, the charge reversal device can comprise at least one means for detecting or determining the state of charge of the at least one capacitive element of the charge reversal branch. Furthermore, the charge reversal device can comprise at least one means for detecting the state of charge of a battery cell, preferably each battery cell, of the series circuit of all battery cells.A sequence of the states "discharge state, charge state" or "discharge state, idle state, charge state" can be repeated periodically. In the mutually corresponding states of the different periods, battery cells different from one another can be discharged or charged in each case. It is possible, for example, for one of the odd battery cells to be charged in each case in the states of charge of periods following one another in time. After all odd battery cells have been charged, one of the even battery cells can then be charged in the states of charge of further periods following one another in time. Between the periodic sequence for charging the odd battery cells and the periodic sequence for charging the even battery cells, recharging of the capacitor in the recharging branch can take place, which is explained in more detail below.It is of course also possible that in the states of charge of time-consecutive periods one of the straight battery cells is charged in each case. After all even battery cells have been charged, one of the odd battery cells can then be charged in each case in the states of charge of further periods following one another in time. Between the periodic sequence for charging the even battery cells and the periodic sequence for charging the odd battery cells, recharging of the capacitor in the charge reversal branch can take place.This advantageously results in a method for carrying out a charge equalization between different battery cells of the series circuit of battery cells of a battery, which improves the ensuring of operability. In particular, the level of a charging or discharging current, i.e. of the current flowing in the discharging or charging state of the transfer device, is limited by the at least one inductive element.A vehicle, in particular a motor vehicle, is further proposed, wherein the vehicle comprises a battery having a plurality of series-connected battery cells and a charge reversal device according to one of the embodiments described in this disclosure.Overall, the transfer device described in this disclosure and the method for operating the transfer device can be embodied or further developed according to one of the embodiments described in the post-published DE 10 2018 221 099.3, in particular a modification described in the claims of these post-published DE 10 2018 221 099.3.The invention is explained in more detail on the basis of exemplary embodiments. The figures show: FIG. 1 shows a schematic circuit diagram of a transfer device according to the invention according to the prior art, FIG. 2 is a schematic circuit diagram of a switching element; and FIG. 3 shows a schematic circuit diagram of a transfer device according to a further embodiment.In the following, the same reference numerals denote elements having the same or similar technical characteristics.FIG. 1 shows a schematic circuit diagram of a charge reversal device 1 according to the invention for a battery according to the prior art, wherein the battery comprises a series connection of a plurality of battery cells BT 1, BT 2, BT 3, BT 4,..., BT 11, BT 12. In FIG. 1, positive poles of the battery cells BT 1,..., BT 12 are represented with a "+" sign and negative poles of the battery cells BT 1,..., BT 12 are represented with a "-" sign. Also shown are battery cell voltages U1, U2, U3, U4,..., U11, U12, this battery cell voltage U1,..., U12 dropping across the respective battery cell BT1,..., BT12.Here, the first battery cell BT 1, the third battery cell BT 3, the fifth battery cell, the seventh battery cell, the ninth battery cell, and the eleventh battery cell BT 11 form odd battery cells of the series circuit. The second battery cell BT 2, the fourth battery cell BT 4, the sixth battery cell, the eighth battery cell, the tenth battery cell, and the twelfth battery cell BT 12 form straight battery cells of the series circuit.The transfer device further comprises switching elements S 1, S 2, S 3, S 4,..., S 12, S 13. In particular, the number of switching elements S 1,..., S 13 of the recharging device 1, which are used to establish or disconnect the electrical connection of positive or negative poles of the battery cells BT 1,..., BT 12 to a first connecting line BL 1 or a second connecting line BL 2, is greater by the number one than the number of series-connected battery cells BT 1,..., BT 12 of the battery.FIG. 1 shows that a positive pole of each odd battery cell BT 1, BT 3,..., BT 11 can be connected to the first connecting line BL 1 via a switching element S 1, S 3... It is also shown that a negative pole of each straight battery cell of the series circuit can also be connected to the first connecting line BL 1 via a switching element S 3,..., S 13. Here, positive poles of all the odd battery cells BT 3,..., BT 11 except for the first battery cell BT 1 are electrically connected to negative poles of the even battery cell BT 2, BT 4,... immediately preceding in the series circuit.Furthermore, it is shown that a positive pole of each straight battery cell BT 2, BT 4,..., BT 12 can be connected to the second connecting line BL 2 via a switching element S 2, S 4,..., S 12. It is further shown that the positive poles of the even battery cells BT 2, BT 4,..., BT 12 are electrically connected to negative poles of the odd battery cell BT 1, BT 3,..., BT 11 respectively immediately preceding in the series connection. Thus, the negative poles of all odd battery cells BT 1, BT 3,..., BT 11 are also electrically connectable to second connecting line BL 2 via switching elements S 2, S 4,..., S 12.It is further shown that the charge reversal device 1 comprises a charge reversal branch 2, wherein a capacitor C is arranged in the charge reversal branch. It is possible for the charge reversal branch to comprise a series circuit of a capacitor C and an inductance, for example an inductor, or to be formed by this. Alternatively, it is possible for the charge reversal branch to comprise a series circuit of a capacitor C and an inductance, e.g. an inductor, and a resistor or to be formed by said series circuit. The series connection of the resistor, the capacitor C and the coil form an oscillating circuit, in particular a damped oscillating circuit. If no resistor is present in the charge reversal branch 2, the series circuit in the charge reversal branch 2 forms an unattenuated resonant circuit.The charge reversal branch 2 has a first connection A 1 and a second connection A 2. The first terminal A 1 is electrically connected, in particular permanently, to the first connecting line BL 1. Furthermore, the first connection A 1 of the charge reversal branch 2 cannot be connected directly or directly to the second connecting line BL 2. In particular, an electrical connection between the first terminal A 1 of the charge reversal branch 2 and the second connecting line BL 2 can be established only via at least one battery cell BT 1,..., BT 12.It is further shown that the second connection A 2 of the charge reversal branch 2 is connected, in particular permanently, to the second connecting line BL 2.In particular, the second terminal A 2 cannot be directly connected to the first connecting line BL 1. Thus, the electrical connection of the second terminal A 2 to the first connection line BL 1 (and thus to the first terminal A 1) can be established only via at least one battery cell BT 1,..., BT 12.Also shown is a capacitor voltage UC which falls across the capacitor C of the charge reversal branch 2 and a coil voltage which falls across the coil L.Schematically shown is a control and evaluation device 3 which can control switching processes of the switching elements S 1,..., S 13. The control and evaluation device 3 can be designed, for example, as a microcontroller or integrated circuit. The switching elements S 1,..., S 13 can be embodied in particular as power switches, further in particular as MOSFETs or IGBTs.Various states, in particular an idling state and a discharging state and a charging state, are explained in DE 10 2018 221 099 A1 described at the beginning.FIG. 2 shows a schematic circuit diagram of a second switching element S 2 and a section of the transfer device 1.A second battery cell BT 2 with the corresponding positive and negative pole is shown. Further illustrated are the first connection line BL 1 and the second connection line BL 2. Schematically illustrated is a first switching element S 1, which can connect the positive pole of the second battery cell BT 2 to the first connecting line BL 1, as already explained with respect to the embodiment illustrated in FIG. 1. The second switching element S 2 is also shown, via which the negative pole of the second battery cell BT 2 can be connected to the second connecting line BL 2.It is shown that the second switching element S2 is formed from a series connection of two MOSFETs TS1, TS2. These MOSFETs TS 1, TS 2 are designed as normally off n-channel MOSFET(s). A drain terminal of the first MOSFET TS 1 is connected to the negative terminal of the second battery cell BT 2. A source terminal of this first MOSFET TS 1 is connected to a source terminal of the second MOSFET TS 2. Further, a drain terminal of the second MOSFET TS 2 is connected to the second connection line BL 2.Also shown are a first switch diode DS 1, which connects the source terminal to the drain terminal of the first MOSFET TS 1, wherein the forward direction of this switch diode DS 1 is oriented from the source terminal to the drain terminal. A second switching diode DS 2 is also present, which connects the source terminal to the drain terminal of the second MOSFET TS 2, wherein the forward direction of this second switching diode DS 2 is oriented from the source terminal to the drain terminal. These switch diodes DS 1, DS 2 are intrinsic switch diodes of the MOSFET TS 1, TS2-Furthermore, a driver circuit 5 is shown, which has a driver voltage terminal 6 and a reference voltage terminal 9. The reference voltage terminal 9 is connected to the source terminals of the MOSFETs TS 1, TS 2. Both a gate terminal of the first MOSFET TS 1 and a gate terminal of the second MOSFET TS 2 are connected to the drive voltage terminal 6. Also shown is a control signal line CS 2 via which a control signal can be transmitted from a control device 7 (see FIG. 3 ) to the driver circuit 5. Depending on this control signal, the driver circuit 5 can then set a desired gate voltage of the two MOSFETs TS 1, TS 2 of the second switching element S 2. In particular, the gate voltage may be set such that the second switching element S 2 is opened or closed. As a result, the states explained above, in particular the state of charge or discharge state explained above, can be set.FIG. 2 shows the configuration of the second switching element S 2 as a series circuit comprising two MOSFETs connected in antiseries. It is possible that other, in particular all, switching elements S 1,..., S 13 of the charge reversal device 1 (see FIG. 1 ) which serve for connecting a pole of a battery cell BT 1,..., BT 12 to a connecting line BL 1, BL 2 is also designed as a series circuit of at least two MOSFETs connected antiseries. In particular, the first switching element S 1 likewise illustrated in FIG. 2, for example, can likewise be embodied as such a series circuit.It is further shown that the driver circuit 5 has a supply voltage connection 8. This is connected to the positive pole of the second battery cell BT 2.A level converter is not shown, wherein a voltage is provided at the drive voltage terminal 6 of the drive circuit by the level converter. By means of the level converter, for example, a level of the voltage present at the supply voltage connection can be converted.FIG. 3 shows a schematic circuit diagram of a transfer device 1 according to a further embodiment of the invention. A charge reversal branch 2 is shown, having a capacitor C and a coil L which are connected in series. As explained above, the charge reversal branch 2 can also comprise only one capacitor C.A first terminal A 1 and a second terminal A 2 of the charge reversal branch 2 are also shown. Further illustrated is a first connection line BL 1 and a second connection line BL 2.The positive poles of each odd battery cell BT 1, BT 3 of the series circuit of battery cells BT 1,..., BT 4 are connectable to the first connecting line BL 1 via switching elements S 1, S 3. The negative poles of each straight battery cell BT 2, BT 4 are connectable to the first connection line BL 1 via switching elements S 3, S 5. The positive poles of each straight battery cell BT 2, BT 4 are connectable to the second connection line BL 2 via switching elements S 2, S 4. Correspondingly, negative poles of each odd battery cell BT 1, BT 3 can be connected to the second connecting line BL 2 via switching elements S 2, S 4.In the embodiment shown in FIG. 3, the first connecting line BL 1 can be connected to the first terminal A 1 and also to the further terminal A 2 by means of a first changeover switching element SA 1. Accordingly, the further connecting line BL 2 can be connected to the first terminal A 1 and also to the further terminal A 2, namely by means of a further changeover switching element SA 2.In this case, the switching elements S 1,..., S 5, via which poles of the battery cells BT 1,..., BT 4 can be connected to connecting lines BL 1, BL 2 or via which the connection between the poles and the connecting lines BL 1, BL 2 can be produced or disconnected, can be referred to as switching elements S 1,..., S 5 of a first switching element level. The switching elements SA 1, SA 2, via which an electrical connection can be established or disconnected between the terminals A 1, A 2 of the charge reversal branch 2 and the connecting lines BL 1, BL 2, can be referred to as switching elements of a second switching element level.In this case, the embodiment illustrated in FIG. 3 comprises switching elements of the first and of the second switching element level. The embodiment shown in FIG. 1 comprises switching elements of the first switching element level, but no switching elements of the second switching element level.Also shown is a control device 7 for controlling the operation of the switching elements S 1,..., S 5 of the first level, which can each be configured in accordance with the embodiment shown in FIG. 2, wherein the control device 7 generates control signals for the operation of these switching elements S 1,..., S 5 and transmits them via control lines CS 1, CS 2, CS 3, CS 4, CS 5 to driver circuits 5 (see FIG. 2 ). A supply voltage terminal of the control device 7 is connected to a negative pole of the fourth battery cell BT 4 of the series circuit of all battery cells BT 1,..., BT 4.Also shown is a control and evaluation device 3 which can control switching operations of the alternating switching elements SA 1, SA 2. It is possible for the control devices 3, 7 to be designed as separate or as common control devices.It is further shown that the positive pole of the first battery cell BT 1 is connected via a first protective line SL 1 to the first connecting line BL 1 and via a second protective line SL 2 to the further connecting line BL 2. A first protective diode SD 1 is arranged in the first protective line SL 1, wherein the forward direction of this first protective diode SD 1 is oriented from the first connecting line BL 1 to the positive pole. A second protective diode SD 2 is arranged in the second protective line SL 2, the forward direction of which is oriented from the second connecting line to the positive pole of the first battery cell BT 1.It is further shown that the negative pole of the fourth and thus last battery cell BT 4 is connected to the first connecting line BL 1 via a third protective line SL 3, wherein a third protective diode SD 3 is arranged in the third protective line SL 3, the forward direction of which is oriented from the negative pole toward the first connecting line BL 1. Correspondingly, a fourth protective diode SD 4 is arranged in a fourth protective line SL 4, the forward direction of which is oriented from the negative pole toward the second connecting line BL 2.List of reference characters1 Charge transfer device 2 Charge transfer branch 3 Control and evaluation device 5 Driver circuit 6 Driver voltage connection 7 Control device 8 Supply voltage connection 9 Reference voltage connection C Capacitor L Coil R Resistance element S 1,..., S 12 Switching element BT 1,..., BT 12 Battery cell BL 1 First connecting line BL 2 Second connecting line A 1 First connection A 2 Second connection UC Capacitor voltage UL Coil voltage SL 1,..., SL 4 Protective line SD 1,..., SD 4 Protective diodes TS 1, TS 2 MOSFET DS 1, DS 2 Switching diodes CS 1,..., CS 5 Control signal lines

Claims

Recharging device for a battery, wherein the battery comprises a series connection of at least two battery cells (BT1,..., BT12), wherein a positive pole of each odd battery cell (BT1, BT3,..., BT11) and a negative pole of each even battery cell (BT2, BT4,..., BT12) of the series connection of all battery cells (BT1,..., BT12) or a first subset of these battery cells (BT1,..., BT12) can be connected via a switching element (S1,...,S12) to a first connecting line (BL1), wherein a positive pole of each even battery cell (BT2, BT4,.., BT12) and a negative pole of each odd battery cell (BT1, BT3,..., bt11) of the series connection of all battery cells (BT1,..., BT12) or of the first subset of these battery cells (BT1,..., BT12) can be connected via a switching element (S1,...,S12) to a further connecting line (BL2), wherein the charge reversal device (1) comprises at least one first charge reversal branch (2) having at least one capacitive element, wherein a first terminal (A1) of the charge reversal branch (2) can be or is connected to the first connecting line (BL1), wherein a further terminal (A2) of the charge reversal branch (2) can be or is connected to the further connecting line (BL2), wherein a switching element (S1,..., S12) is formed by at least two transistor switches connected in antiseries, wherein the charge reversal device (1) comprises, for each switching element (S1,..., S12), a driver circuit (5) having a driver voltage terminal (6), wherein a gate terminal of each transistor switch of a switching element (S1,..., S12) is in each case connected to the driver voltage terminal (6) of the driver circuit (5) of the switching element (S1,..., S12), characterized in that the charge reversal device (1) comprises a control device (7) for controlling the driver circuits (5), wherein a supply voltage terminal of the control device (7) is connected to a negative pole of the last battery cell (BT4, BT12) of the series circuit of all battery cells (BT1,..., BT12) or of the first subset.Transfer device according to Claim 1, characterized in that a supply voltage connection (8) of the driver circuit (5) of a switching element (S1,..., S12) which is connected to a negative pole of a battery cell (BT1,..., BT12) is electrically connected to a positive pole of the battery cell (BT1,..., BT12).Transfer device according to Claim 2, characterized in that the voltage at the driver voltage connection (6) is provided by means of a level converter.Transfer device according to one of the preceding claims, characterized in that the positive pole of the first battery cell (BT1) of the series circuit of all battery cells (BT1,..., BT12) or of the first subset is connected via a first protective line (SL1) to the first connecting line (BL1) and via a second protective line (SL2) to the further connecting line (BL2), wherein at least one diode (SD1, SD2) is arranged in each protective line (SL1, SL2).Transfer device according to one of the preceding claims, characterized in that the negative pole of the last battery cell (BT4, BT12) of the series circuit of all battery cells (BT1,..., BT12) or of the first subset is connected via a third protective line (SL3) to the first connecting line (BL1) and via a fourth protective line (SL4) to the further connecting line (BL2), wherein at least one diode (SD3, SD4) is arranged in each protective line (SL3, SL4).Transfer device according to one of the preceding claims, characterized in that the transfer branch (2) comprises a series circuit of at least one capacitive element, at least one inductive element and at least one resistive element and / or in that the transfer device (2) comprises at least one means for detecting or determining a voltage across the capacitive element of a transfer branch (2) and at least one means for detecting or determining a voltage across the inductive element of a transfer branch (2).Transfer device according to one of the preceding claims, characterized in that the transfer device (2) comprises a further transfer branch, wherein the further transfer branch comprises a series circuit of at least one capacitive element and at least one inductive element, wherein a first terminal of the further transfer branch is connectable or connected to a third connecting line, wherein a further terminal of the further transfer branch is connectable or connected to a fourth connecting line, wherein a positive pole of each odd battery cell and a negative pole of each even battery cell of all battery cells (BT1,..., BT12) or a further subset of these battery cells (BT1,..., BT12) is connectable to the third connecting line via a switching element, wherein a positive pole of each even battery cell (BT2,..., bt 12) and a negative pole of each odd battery cell (BT 1,..., BT 11) of all battery cells (BT 1,..., BT 12) or of the further subset of these battery cells (BT 1,..., BT 12) can be connected to the fourth connecting line via a switching element.Method for operating a charge reversal device (1) according to one of Claims 1 to 7, characterized in that, in a discharged state, a first subsection of the series connection of all battery cells (BT1,..., BT12) is connected to the charge reversal branch (2), wherein, in a charged state, a further subsection of the series connection of all battery cells (BT1,..., BT12) is connected to the charge reversal branch (2), wherein at least one battery cell (BT1,..., BT12) of the first subsection is not part of the further subsection.Vehicle having a battery and a charge reversal device (1) according to one of Claims 1 to 7.

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