DE102010031846A1 - Circuit arrangement for exchanging electric charge between secondary cells in e.g. electric vehicle, has secondary cells associated with modules of rechargeable battery, and series circuits connected with secondary cells - Google Patents

Abstract

The arrangement has series circuits comprising connection pairs connected with secondary cells (911-948) of modules (91-94) of a rechargeable battery (9), where the connection pairs are assigned to a group of series circuits. A set of inductive storage elements (151-183) of the group of the series circuits is inductively coupled with another set of inductive storage elements (25-28) of another group of series circuits. The latter set of circuits is connected with the modules, and the secondary cells are associated with the modules. The former set of circuits is connected with the cells. An independent claim is also included for a method for exchanging electric charge between secondary cells.

Description

The invention relates to a circuit arrangement and a method for exchanging electrical charge between secondary cells of a secondary battery, with secondary cells connected in series.

From the publication with the publication number DE 10 2008 021 090 A1 Such a circuit arrangement and such a method is known. In the known circuit arrangement, first series circuits are provided which each have a first controllable switching element and a first inductive storage element and in each case a connection pair for connection to one of the secondary cells of the accumulator. When connected to the circuit accumulator each first series circuit is connected in parallel to a secondary cell of the accumulator. The circuit arrangement has a second series circuit with a second controllable switching element and a second inductive storage element. This second series circuit has a connection pair for connection to the poles of the accumulator. In the state connected to the accumulator, the accumulator and the second series circuit are connected in parallel. The first inductive storage elements are inductively coupled to the second inductive storage element so that electrical energy from one, several or all first storage elements can be transferred to the second storage element and vice versa transmit electrical energy from the second inductive storage element to one, several or all first inductive storage elements can be.

According to the published in the publication DE 10 2008 021 090 A1 disclosed method, can be determined by switching the first and the second switching element, the direction of the energy flow and - associated - the charge transport. The inductive coupling of the first memory elements with the second memory element forms a transformer. However, a transformer can not transmit direct current but only alternating current. Thus, the switching elements that are in series with the inductive storage element that is to transmit the energy must not be permanently closed. Rather, the direct current must be "chopped" by repeated switching and thus converted into an alternating current. After the transformation then the alternating current must be converted back into a direct current, which is possible by a corresponding switching of the switching element that is in series with the storage element to which the energy has been transferred. Accumulators will be used now and even more in the future in vehicles with electric or hybrid drives. To operate the electric motors accumulators are needed as rechargeable energy storage. The accumulators must be able to deliver high currents at high voltages in order to provide sufficient power. The accumulators used therefore have a plurality of secondary cells connected in series. Often several strings of series connected secondary cells are connected in parallel to provide the necessary currents.

In the published patent application DE 10 2008 021 090 A1 is stated that due to production or due to different wear during operation, the individual secondary cells can have different capacities. As a result, individual secondary cells are fully charged earlier than others during the charging process. The charging process should then be terminated as soon as one of the secondary cells has reached its maximum state of charge, as otherwise damage or destruction of the charged secondary cell may occur. Conversely, during a discharge, a secondary cell may be discharged earlier than the others to below its operating range. The discharge process should be terminated as soon as one of the accumulators is discharged to below its working range in order to avert damage from the secondary cell.

By in the published patent application DE 10 2008 021 090 A1 described device and the method described there can now achieve an exchange of electrical charge between secondary cells of a battery. With the device or with the method can now be ensured that in case of complete charging of a secondary cell when charging the battery charge is distributed from the fully charged secondary cell to the not yet fully charged cells. Furthermore, in the case of a secondary cell discharged under the working area, a charge of not yet completely discharged secondary cells can be transferred to the discharged secondary cell. In both cases, a charge exchange takes place, which leads to an overall larger charge or discharge and thus use of the accumulator.

A technical problem arises in the practical implementation of the method due to the high voltage required in electric vehicles or in hybrid vehicles and the consequent need for connecting many in many, more than 100 secondary cells in series. The charge exchange takes place via the inductive coupling of the first inductive storage elements to the second inductive storage element. Technically, this coupling is realized by a transformer with a number corresponding to the number of secondary cells primary windings and a secondary winding. With a number of up to or even over 100 secondary cells, a transformer becomes very bulky and heavy. In part, the limits of the technically feasible are reached.

This is where the invention starts.

The invention is based on the technical problem of the circuit arrangement and the method according to the published patent application DE 10 2008 021 090 A1 so that it can be used in motor vehicles, but the application of the invention is not limited to the automotive sector.

• – dass die Schaltungsanordnung die zweite Reihenschaltung mehrfach aufweist und jede zweite Reihenschaltung ein Anschlusspaar zum Verbinden mit einem Modul des Akkumulators umfassend einige der in Reihe geschalteten Sekundarzellen des Akkumulators aufweist,
• – dass die ersten Reihenschaltungen, deren Anschlusspaare zum Verbinden mit den Sekundärzellen eines der Module geeignet und eingerichtet sind, einer Gruppe von ersten Reihenschaltungen zugeordnet sind und
• – dass die ersten induktiven Speicherelemente jeder der ersten Gruppen von ersten Reihenschaltungen induktiv mit dem zweiten induktiven Speicherelement derjenigen zweiten Reihenschaltung gekoppelt sind, die zum Verbinden mit demjenigen Modul geeignet und eingerichtet ist, dem die Sekundärzellen zugehörig sind, mit denen die ersten Reihenschaltungen der vorgenannten Gruppe verbunden sind.

With regard to the circuit arrangement, the problem is first solved by

• That the circuit arrangement has the second series connection in multiple and each second series circuit has a connection pair for connection to a module of the accumulator comprising some of the series-connected secondary cells of the accumulator,
• - That the first series circuits whose terminal pairs are suitable for connection to the secondary cells of one of the modules and arranged, are assigned to a group of first series circuits, and
• - That the first inductive storage elements of each of the first groups of first series circuits are inductively coupled to the second inductive storage element of that second series circuit suitable and adapted for connection to the module to which the secondary cells are associated, with which the first series circuits of the aforementioned group are connected.

According to the invention, the charge exchange does not take place between the secondary cells of the whole accumulator. Rather, the accumulator is divided into modules of series-connected secondary cells. The modules themselves are also connected in series. The charge exchange then takes place between the secondary cells of a module. The transformer required for this purpose with the first inductive storage elements and the second inductive storage element can have a significantly smaller design than would have been the case with a circuit arrangement known from the prior art.

It should be noted that an accumulator which can be connected to the circuit arrangement according to the invention in order to effect a charge exchange between the secondary cells of the accumulator need not differ from a conventional accumulator. The subdivision of the accumulator into modules from secondary cells can be effected solely by the circuit according to the invention. Changes to the accumulator are not necessarily associated with this.

The invention is based on the (statistical) finding that, in the case of an accumulator with a large number of secondary cells (for example 100 cells) and a significantly smaller number of secondary cells per module (for example 10 cells), it is unlikely that all of the deeply discharged or all highly charged secondary cells are assigned to a module. Rather, it is assumed that the mean value of the voltages of the secondary cells of all modules is approximately equal and thus a charge exchange within a module is sufficient.

• – mehrere zweite Reihenschaltungen jeweils aus einem zweiten steuerbaren Schaltelement und einem zweiten induktiven Speicherelement und jeweils mit einem Anschlusspaar zum Verbinden mit einem Modul des Akkumulators aufweist und
• – eine dritte Reihenschaltung aus einem dritten steuerbaren Schaltelement und einem dritten induktiven Speicherelement und mit einem Anschlusspaar zum Verbinden mit dem Akkumulator aufweist.

However, the problem underlying the invention can also be achieved according to the invention in that in a circuit arrangement for exchanging electrical charge between, connected in series modules of a battery, which is composed of series-connected secondary cells, the circuit arrangement

• - Has a plurality of second series circuits each of a second controllable switching element and a second inductive storage element and each with a pair of terminals for connecting to a module of the accumulator and
• - Has a third series circuit of a third controllable switching element and a third inductive storage element and with a pair of terminals for connection to the accumulator.

According to the invention, the second inductive storage elements may be inductively coupled to the third inductive storage element.

In this solution, the charge exchange does not necessarily take place within the modules of the accumulator. The charges are rather exchanged between the modules. As a result of a charge exchange between the modules, it also comes to a charging or discharging of the individual secondary cells, which may not always but often have the desired effect.

It is particularly advantageous if you can combine both solutions and then take place a charge exchange within a module and between the modules.

The inductive storage elements can be arranged as conductor windings on a circuit carrier. It is thus possible to use so-called printed circuit board transformers for inductive coupling, which are inexpensive to produce. The in ductive coupling of the inductive storage elements can be done by ferrite cores, for example, are slipped over the windings of the PCB transformer.

The circuit arrangement may have a control and monitoring unit, which is suitable and arranged for monitoring the voltages of the secondary cells and for driving the controllable switching elements.

With regard to the method, the problem underlying the invention is solved in that the secondary cells are arranged in series in a module of the accumulator and the modules are connected in series, wherein for exchanging the charge between the secondary cells of the module, a first inductive Storage element, which is arranged in a first series circuit parallel to one of the secondary cells of the module, and a second inductive storage element, which is arranged in a second series connection parallel to the module, to be charged or discharged.

This method according to the invention enables a charge exchange within a module of a rechargeable battery.

The problem may be further solved by a method of exchanging electrical charge between series-connected modules of a battery composed of series-connected secondary cells, wherein in the method of exchanging the charge between the modules, a second inductive storage element incorporated in a first series circuit is arranged parallel to one of the secondary cells of the module, and a second inductive storage element, which is arranged in a second series connection parallel to the module, to be charged or discharged.

Also a charge exchange between the modules of a rechargeable battery can solve the problem. However, it is particularly advantageous if the method for exchanging charges within a module and the method for exchanging charges between the modules are combined in one method. Thus, it may be particularly advantageous if initially a charge exchange between the modules takes place in order to distribute the charge evenly on the modules. Subsequently, the charge can then be distributed within the modules, which then overall a uniform charge of the secondary cells of the battery is achieved.

Reference to the accompanying drawings, the invention is explained in more detail below. It shows:

1 a circuit diagram of a preferred embodiment of a circuit arrangement according to the invention with a battery in a simplified representation.

The in the 1 illustrated circuit arrangement according to the invention is to the accumulator 9 connected. The accumulator 9 exemplifies twelve series connected secondary cells 911 to 943 on, each three a module 91 to 94 assigned. So are the module 91 the secondary cells 911 . 912 . 913 assigned. The module 92 includes the secondary cells 921 . 922 . 923 , The secondary cells 931 . 932 . 933 are the module 93 and the secondary cells 941 . 942 . 943 are the module 94 assigned.

Between taps of the secondary cells 911 to 943 connections are provided. About this and about a negative and a positive pole 95 . 96 is the accumulator 9 connected to the circuit arrangement according to the invention.

The circuit arrangement according to the invention comprises first series circuits, each of a first controlled switching element 111 to 143 and a first inductive storage element 151 to 183 , These series circuits each have a pair of terminals with the taps of a secondary cell 911 to 943 connected to the series connection in parallel with the secondary cell 911 to 943 to switch. Control terminals of the first controlled switching elements 111 to 143 are connected via lines not shown with a control and monitoring unit, also not shown.

The voltage of each secondary cell 911 to 943 and the voltage of each module 91 to 94 are also fed to the control and monitoring unit, where they can be monitored for the purpose of carrying out the method according to the invention. The control and monitoring unit may, for example, in one in the DE 10 2008 021 090 A1 be executed manner shown.

The circuit arrangement according to the invention also comprises four second series circuits, each of a second controlled switching element 21 to 24 and a second inductive storage element 25 to 28 , These second series circuits each have a pair of terminals, with taps of the modules 91 to 94 connected to every second series connection in parallel with a module 91 to 94 to switch.

Control terminals of the second controlled switching elements 21 to 24 are also connected via lines not shown with the control and monitoring unit, also not shown.

Finally, the illustrated circuit arrangement according to the invention has a third series circuit, which comprises a third controlled switching element 31 and a third inductive coupling element 32 having. This third series connection has a connection pair with the poles 95 . 96 of the accumulator 9 connected is. The accumulator 9 and the third series circuit are connected in parallel.

There are various methods with which the circuit arrangement according to the invention can be operated. A method will be described below by way of example.

If the state of charge no secondary cell 911 to 943 at the upper limit or at the lower limit of the working range, so neither an overcharge nor a deep discharge of a secondary cell 911 to 943 threatens, it may be useful initially, a charge exchange between the modules 91 to 94 bring about the charge of the modules 91 to 94 to bring it to the same level. For example, one could partially discharge the module with the highest charge and the charge on all modules 91 to 94 to distribute. For example, would be the module 91 the one with the highest charge, could be the controlled switching element 21 repeatedly close to the second inductive storage element 25 by unloading the module 91 with an alternating current generated by the repeated switching. By the inductive coupling of the second inductive storage element 25 and the third inductive storage element 32 becomes one over the third inductive storage element 32 declining voltage induces to charge the entire accumulator 9 leads. But this must be the AC voltage on the third inductive storage element 32 be converted into a direct current, which by a clever driving the third controlled switching element 31 he follows. By charging the entire battery 9 will be the one from the module 91 removed charge on all modules 91 to 94 distributed.

Alternatively, you could also get the charge from all the modules 91 to 94 and this targeted to one of the modules 91 to 94 transfer. In this case, first repeatedly disconnect the third controlled switching element 31 so that the over the entire accumulator 9 decreasing voltage the third inductive coupling element 32 charging. In addition, the second controlled switching element is repeatedly closed that the module to be charged 91 to 94 assigned. Should the in the third inductive storage element 32 cached charge, for example, on the module 93 be transmitted, the second controlled switching element would have 23 be closed repeatedly.

Is the charge between the modules 91 to 94 then distributed so that above them an equal or almost equal voltage drops, in further steps charges within the modules 91 to 94 be exchanged to the secondary cells 911 to 943 bring in an approximately same state of charge. Also the charge exchange within the modules 91 to 94 via inductive storage elements, namely the first inductive storage elements 151 to 183 , For example, if the charge from the secondary cell 922 on all secondary cells 921 to 923 of the second module 92 be distributed, first, the first controlled switching element 122 activated for repeated closing. The first inductive storage element 162 in that in series with the controlled switching element 122 is then from the secondary cell 922 charged. In addition, the second controlled switching element 22 repeatedly closed. The in the first inductive storage element 122 stored energy is applied to the second inductive storage element 26 which results in an induction of a voltage in the second inductive storage element 26 leads. This voltage is then in the second module 92 and leads to a charging of all secondary cells 921 . 922 . 923 of the module 92 ,

In contrast, the charge targeted to a secondary cell 911 to 943 a module 91 to 94 must be transferred, the second controlled switching element associated with the module must first be closed repeatedly. This then leads to the charging of the second inductive storage element, which is in series with the second controlled switch. If the first controlled switching element associated with the secondary cell to be charged is also closed repeatedly, the energy is transferred to the first inductive storage element arranged in series with the closed first controlled switching element, which leads to a charging of the desired secondary cell.

LIST OF REFERENCE NUMBERS

111 to 143

first switching elements

151 to 183

first inductive storage elements

21 to 24

second switching elements

25 to 28

second inductive storage elements

31

third switching element

32

third inductive storage element

41

Ferrite cores between the first memory elements and the second memory elements

42

Ferrite core between the second memory elements and the third memory element

9

accumulator

91 to 94

Modules of the accumulator

911 to 943

Secondary cells of the accumulator

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102008021090 A1 [0002, 0003, 0004, 0005, 0008, 0028]

Claims (8)

Circuit arrangement for exchanging electrical charge between secondary cells ( 911 to 943 ) of an accumulator ( 9 ) derived from the series-connected secondary cells ( 911 to 943 ), wherein the circuit arrangement comprises first series circuits each of a first controllable switching element and a first inductive storage element and in each case with a connection pair for connection to one of the secondary cells ( 911 to 943 ) of the accumulator ( 9 ) and - wherein the circuit arrangement has a second series circuit with a second controllable switching element ( 21 to 24 ) and a second inductive storage element ( 25 to 28 ), characterized in that - the circuit arrangement has the second series circuit in multiple, and every second series circuit has a terminal pair for connection to a module ( 91 to 94 ) of the accumulator ( 9 ) comprising some of the series-connected secondary cells ( 911 to 943 ) of the accumulator ( 9 ), - that the first series circuits, their terminal pairs for connecting to the secondary cells ( 911 to 943 ) of a module ( 91 to 94 ) are suitable and arranged, are assigned to a group of first series circuits, and - that the first inductive storage elements ( 151 to 183 ) each of the first groups of first series circuits inductively with the second inductive storage element ( 25 to 28 ) of the second series circuit connected to the module ( 91 to 94 ) is adapted and set up, to which the secondary cells ( 911 to 948 ) are associated with which the first series circuits of the aforementioned group are connected. Circuit arrangement for exchanging electrical charge between modules connected in series ( 91 to 94 ) of an accumulator ( 9 ) consisting of series-connected secondary cells ( 911 to 948 ), in particular circuit arrangement according to claim 1, characterized in that the circuit arrangement - a plurality of second series circuits each consist of a second controllable switching element ( 21 to 24 ) and a second inductive storage element ( 25 to 28 ) and each with a connection pair for connecting to the module of the accumulator ( 9 ) and - a third series connection of a third controllable switching element ( 31 ) and a third inductive storage element ( 32 ) and with a connection pair for connecting to the accumulator ( 9 ) having. Circuit arrangement according to Claim 2, characterized in that the second inductive storage elements ( 25 to 28 ) with the third inductive storage element ( 32 ) are inductively coupled. Circuit arrangement according to one of claims 1 to 3, characterized in that the inductive storage elements ( 151 to 183 . 25 to 28 . 32 ) are arranged as conductor turns on a circuit carrier. Circuit arrangement according to one of claims 1 to 4, characterized in that the inductive coupling of the inductive storage elements ( 151 to 183 . 25 to 28 . 32 ) by ferrite cores ( 41 . 42 ) he follows. Circuit arrangement according to one of claims 1 to 5, characterized in that the circuit arrangement has a control and monitoring unit, which for monitoring the voltages of the secondary cells and for driving the controllable switching elements ( 111 to 143 . 21 to 24 . 32 ) is suitable and furnished. Method for exchanging electrical charge between secondary cells ( 911 to 943 ) of an accumulator ( 9 ), characterized in that the secondary cells ( 911 to 943 ) connected in series in a module ( 91 to 94 ) of the accumulator ( 9 ) and the modules ( 91 to 94 ) are connected in series, in particular for implementation with a circuit arrangement according to one of claims 1 to 6, wherein for exchanging the charge between the secondary cells ( 911 to 943 ) of the module ( 91 to 94 ) a first inductive storage element ( 151 to 183 ), which in a first series connection parallel to one of the secondary cells ( 911 to 948 ) of the module ( 91 to 94 ), and a second inductive storage element ( 25 to 28 ), in a second Series connection parallel to the module ( 91 to 94 ) is arranged to be loaded or unloaded. Method for exchanging electrical charge between modules connected in series ( 91 to 94 ) of an accumulator ( 9 ) consisting of series-connected secondary cells ( 911 to 943 ), in particular the method according to claim 7 and / or in particular for implementation with a circuit arrangement according to one of claims 2 to 6, characterized in that for exchanging the charge between the modules ( 91 to 94 ) a second inductive storage element ( 25 to 28 ), which in a first series connection parallel to one of the secondary cells ( 911 to 943 ) of the module ( 91 to 94 ), and a second inductive storage element ( 25 to 28 ) arranged in a second series connection parallel to the module ( 91 to 94 ) is arranged to be loaded or unloaded.

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