Battery system and method for providing an intermediate voltage
The invention relates to a battery system ( 10 ), comprising a battery module ( 11 ), which comprises a first high-voltage connection ( 12 a ), a second high-voltage connection ( 12 b ) and a multiplicity of battery cell modules ( 11 a, . . . , 11 n ) which are connected in series between the first and second high-voltage connections, and a switching matrix ( 13 ). The switching matrix comprises a large number of switching rails ( 14 ), which are each connected to one of the nodes between in each case two of the battery cell modules which are connected in series, a multiplicity of first switching devices ( 15 a ), which are designed to connect in each case one of the switching rails ( 14 ) to a first low-voltage connection ( 13 a ) of the switching matrix ( 13 ), and a multiplicity of second switching devices ( 15 b ), which are designed to connect in each case one of the switching rails ( 14 ) to a second low-voltage connection ( 13 b ) of the switching matrix. In this case, a first total voltage (HV) of all of the battery cell modules ( 11 a, . . . , 11 n ) which are connected in series is present between the first high-voltage connection ( 12 a ) and the second high-voltage connection ( 12 b ), and a second total voltage (LV) of some of the battery cell modules ( 11 a, . . . , 11 n ) which are connected in series is present between the first low-voltage connection ( 13 a ) and the second low-voltage connection ( 13 b ), depending on the switching state of the first switching devices ( 15 a ) and the second switching devices ( 15 b ).
1. A battery system ( 10 ), having:
a battery module ( 11 ) that comprises a first high voltage connector ( 12 a ), a second high voltage connector ( 12 b ) and a plurality of battery cell modules ( 11 a , . . . , 11 n ) that are connected in series between the first and second high voltage connector; and
said battery system having a switching matrix ( 13 ) that comprises:
a plurality of switching rails ( 14 ) that are connected in each case to one of the nodes between in each case two of the battery cell modules ( 11 a , . . . , 11 n ) that are connected in series,
a plurality of first switching devices ( 15 a ) that are embodied for the purpose of connecting in each case one of the switching rails ( 14 ) to a first low voltage connector ( 13 a ) of the switching matrix ( 13 ),
a plurality of second switching devices ( 15 b ) that are embodied for the purpose of connecting in each case one of the switching rails ( 14 ) to a second low voltage connector ( 13 b ) of the switching matrix ( 13 ),
a plurality of third switching devices ( 15 c ) that are embodied for the purpose of connecting respectively one of the switching rails ( 14 ) to a first intermediate connector of the switching matrix ( 13 ), and
a plurality of fourth switching devices ( 15 d ) that are embodied for the purpose of connecting respectively one of the switching rails ( 14 ) to a second intermediate connector of the switching matrix ( 13 ),
wherein a first total voltage (HV) of all series-connected battery cell modules ( 11 a , . . . , 11 n ) is available between the first ( 12 a ) and the second high voltage connector ( 12 b ),
wherein a second total voltage (LV) of a part of the series-connected battery cell modules ( 11 a , . . . , 11 n ) is available between the first ( 13 a ) and the second low voltage connector ( 13 b ) in dependence upon the switching state of the first ( 15 a ) and second switching devices ( 15 b ),
wherein a third total voltage of a part of the series-connected battery cell modules ( 11 a , . . . , 11 n ) is available between the first low voltage connector ( 13 a ) and the first intermediate connector in dependence upon the switching state of the first ( 15 a ) and third switching devices ( 15 c ) and
wherein a fourth total voltage of a part of the series-connected battery cell modules ( 11 a , . . . , 11 n ) is available between the second low voltage connector ( 13 b ) and the second intermediate connector in dependence upon the switching state of the second ( 15 b ) and fourth switching devices ( 15 d ).
2. The battery system ( 10 ) as claimed in claim 1 , wherein the switching matrix ( 13 ) further comprises:
two further switching rails ( 14 ) that are connected in each case to the first ( 12 a ) and
the second high voltage connector ( 12 b ), and
further first and second switching devices ( 15 a , 15 b ) that are embodied in each case for the purpose of connecting respectively one of the two further switching rails ( 14 ) to the first low voltage connector ( 13 a ) or the second low voltage connector ( 13 b ) of the switching matrix ( 13 ).
3. The battery system as claimed in claim 1 , further having:
a first DC current converter ( 16 a ) with two input connectors that are coupled to the first low voltage connector ( 13 a ) and the first intermediate connector; and
a second DC current converter ( 16 c ) with two input connectors that are coupled to the second low voltage connector ( 13 b ) and the second intermediate connector,
wherein the first and the second DC current converters ( 16 a , 16 c ) are connected in series in each case by way of output connectors, so that a current-converted total voltage (LV′) of the third and fourth total voltage is available in each case between second output connectors of the first and second DC current converters ( 16 a , 16 c ).
4. The battery system ( 10 ) as claimed in claim 3 further having:
a first direct current voltage intermediate circuit with a first capacitor ( 17 a ) that is coupled between the first low voltage connector ( 13 a ) and the first intermediate connector; and
a second direct current voltage intermediate circuit with a second capacitor ( 17 c ) that is coupled between the second low voltage connector ( 13 b ) and the second intermediate connector.
5. The battery system ( 10 ) as claimed in claim 1 , further having:
a DC current converter ( 16 ) with two input connectors that are coupled between the first ( 13 a ) and second low voltage connectors ( 13 b ) as well as having two output connectors at which it is possible to tap a current-converted second total voltage.
6. The battery system ( 10 ) as claimed in claim 1 , further having:
a direct current voltage intermediate circuit with a capacitor ( 17 ) that is coupled between the first ( 13 a ) and the second low voltage connector ( 13 b ).
7. The battery system ( 10 ) as claimed in claim 1 , further having:
a plurality of connection devices ( 18 ) that in each case comprise a series connection of an ohmic resistor ( 18 a ) and a switch ( 18 b ), and that are coupled between in each case two of the switching rails ( 14 ) of the switching matrix ( 13 ).
8. A method ( 30 ) for generating an intermediate voltage (LV) in a battery system ( 10 ) as claimed in claim 1 , comprising the steps of:
determining the charge condition of the series-connected battery cell modules ( 11 a , . . . , 11 n );
selecting a predefined number of battery cell modules ( 11 a , . . . , 11 n ), which comprise the highest charge condition; and
controlling the first and second switching devices ( 15 a , 15 b ) of the switching matrix, in such a manner that a total voltage (LV) of the selected battery cell modules ( 11 a , . . . , 11 n ) is available between the first and second low voltage connector ( 13 a , 13 b ) in dependence upon the switching state of the first and second switching devices ( 15 a , 15 b ).
9. The method ( 30 ) as claimed in claim 8 , wherein the charge condition of the selected battery cell modules ( 11 a , . . . , 11 n ) is compared to the charge condition of the remaining battery modules ( 11 a , . . . , 11 n ), and wherein the selection of the battery cell modules ( 11 a , . . . , 11 n ) is changed as soon as the charge condition of the currently selected battery cell modules ( 11 a , . . . , 11 n ) falls below the charge condition at least of one of the remaining battery cell modules ( 11 a , . . . , 11 n ).