Device and method for operating a motor vehicle, and motor vehicle
The invention relates to a device ( 1 ) for operating a motor vehicle, comprising an electrical drive system with an electrical high-voltage traction network ( 2 ) and an operating network ( 3 ) that has a high-voltage unit ( 7 ) comprising a power electronics system ( 5 ), and a low-voltage unit ( 6 ) comprising a control electronics system ( 4 ), and a first transformer ( 8 ) designed to convert an input voltage (U 1 ) from the low-voltage unit ( 6 ) into a first, particularly higher output voltage (U 2 ) for the power electronics system ( 5 ). According to the invention, the dev ice comprises at least one second transformer ( 11 ) designed to convert the first output voltage (U 2 ) of the first transformer ( 8 ) into a second output voltage (U 3 ) for the control electronics system ( 4 ), the second output voltage (U 3 ) being higher than the input voltage (U 1 ).
1. A device ( 1 ) for operating a motor vehicle, the device comprising:
an electrical drive system having an electrical high-voltage traction network ( 2 ) and an operating network ( 3 ), the operating network ( 3 ) including
a high-voltage part ( 7 ) having a power electronics system ( 5 ),
a low-voltage part ( 6 ) having a control electronics system ( 4 ), and
a first transformer ( 8 ) configured to convert an input voltage (U 1 ) from the low-voltage part ( 6 ) into a first output voltage (U 2 ) for the power electronics system ( 5 ), wherein the first output voltage (U 2 ) is greater than the input voltage (U 1 ), and
at least one second transformer ( 11 ) configured to convert the first output voltage (U 2 ) of the first transformer ( 8 ) into a second output voltage (U 3 ) for the control electronics system ( 4 ), wherein the second output voltage (U 3 ) is higher than the input voltage (U 1 ).
2. The device as claimed in claim 1 , the device including a diagnostic unit ( 13 ), configured to monitor the operation of the operating network ( 3 ), wherein the diagnostic unit ( 13 ) is connected to a switching device, by means of which the traction network can be electrically connected to the high-voltage part ( 7 ).
3. The device as claimed in claim 1 , further comprising a first diode arrangement ( 14 ), which is configured in such a manner that the power electronics system ( 5 ) is supplied either by the traction network ( 2 ) or by the operating network ( 3 ) depending on an operating voltage (U 4 ) of the traction network ( 2 ) and the output voltage (U 2 ) of the first transformer ( 8 ).
4. The device as claimed in claim 3 , wherein the output voltage (U 2 ) of the first transformer ( 8 ) is lower than a lowest predicted operating voltage (U 4 ) of the traction network ( 2 ).
5. The device as claimed in claim 3 , further comprising a second diode arrangement ( 12 ), which is configured in such a manner that the control electronics system ( 4 ) is supplied either by the low-voltage part ( 6 ) or by the second transformer ( 11 ) depending on the operating voltage (U 1 ) of the low-voltage part ( 6 ) and the output voltage (U 3 ) of the second transformer ( 11 ).
6. The device as claimed in claim 1 , wherein the output voltage (U 3 ) of the second transformer ( 11 ) is higher than the highest predicted operating voltage of the low-voltage part ( 6 ).
7. The device as claimed in claim 1 , wherein a boost converter ( 18 ) is connected upstream of the power electronics system ( 4 ) and the first transformer ( 8 ).
8. The device as claimed in claim 1 , wherein an actuatable switch ( 19 ) is interposed between the control electronics system ( 4 ) and the second transformer ( 11 ).
9. A motor vehicle comprising an electrical drive system with an electrical high-voltage traction network ( 2 ) and an operating network ( 3 ) which has a high-voltage part ( 7 ) having a power electronics system ( 5 ) and a low-voltage part ( 6 ) having a control electronics system ( 4 ), and a first transformer ( 8 ) configured to convert an input voltage (U 1 ) from the low-voltage part ( 6 ) into a first output voltage (U 2 ) for the power electronics system ( 5 ), wherein the first output voltage (U 2 ) is greater than the input voltage (U 1 ), and at least one second transformer ( 11 ) configured to convert the first output voltage (U 2 ) of the first transformer ( 8 ) into a second output voltage (U 3 ) for the control electronics system ( 4 ), wherein the second output voltage (U 3 ) is higher than the input voltage (U 1 ).
10. A method for operating a motor vehicle comprising an electrical drive system with an electrical high-voltage traction network ( 2 ) as well as an operating network ( 3 ) which has a high-voltage part ( 7 ) having a power electronics system ( 5 ) and a low-voltage part ( 6 ) having a control electronics system ( 4 ), wherein an input voltage (U 1 ) from the low-voltage part is converted by a first transformer ( 8 ) into a higher output voltage (U 2 ) for the power electronics system ( 5 ), wherein the output voltage (U 2 ) of the first transformer ( 8 ) is converted into a second output voltage (U 3 ) for the control electronics system ( 4 ), wherein the second output voltage (U 3 ) is selected to be higher than the input voltage (U 1 ).