ADAPTIVE FILTER WITH Y CAPACITORS FOR A 3-PHASE DC ON-BOARD ELECTRICAL SYSTEM
Power converter includes first, second and third lines, and a filter device. First to third terminals are connected to the first to third lines, and first and second capacitors form a central node connected to the third terminal. Third and fourth capacitors are connected between first capacitor and first terminal, and second capacitor and second terminal. A switching device switches between first and second filter modes, the first forming a first interference current path on the first line from the first terminal via the third capacitor, a parallel connection of the first and second capacitors and the central node to the third terminal, and a second interference current path on the second line from the second terminal via the fourth capacitor, a parallel connection of the first and second capacitors and the central node. In second filter mode interference currents along the current paths is reduced.
1 . Power converter for an on-board electrical system of an electrically driveable vehicle having a first line for a first potential, a second line for a second potential, a third line for a reference potential and a filter device that has
a first terminal that is connected to the first line,
a second terminal that is connected to the second line,
a third terminal that is connected to the third line,
a first capacitor and a second capacitor, between which a central node is formed with an electrically conductive connection to the third terminal, and
a switching device that is configured to switch between a first filter mode and a second filter mode of the filter device on the basis of control information,
wherein
the filter device furthermore comprises
a third capacitor, which is connected between a terminal of the first capacitor facing away from the central node and the first terminal of the filter device, and
a fourth capacitor, which is connected between a terminal of the second capacitor facing away from the central node and the second terminal of the filter device,
wherein in the first filter mode
a first current path for an interference current is formed on the first line from the first terminal of the filter device via the third capacitor, a parallel connection of the first capacitor and the second capacitor and the central node to the third terminal of the filter device, and
a second current path for an interference current is formed on the second line from the second terminal of the filter device via the fourth capacitor, a parallel connection of the first capacitor and the second capacitor and the central node to the third terminal of the filter device,
wherein, in the second filter mode, an admittance for the interference currents along the first current path and the second current path is at least reduced compared to the first filter mode.
2 . Power converter according to claim 1 , wherein
the filter device is set up to set a higher pole frequency and/or a lower effective total capacitance for filtering the interference currents in the second filter mode between the first terminal and the third terminal and between the second terminal and the third terminal than in the first filter mode.
3 . Power converter according to claim 1 , wherein
in the second filter mode
the admittance along the first current path between the third capacitor and the second capacitor is at least reduced compared to the first filter mode and the admittance along the second current path between the fourth capacitor and the first capacitor is at least reduced compared to the first filter mode, or
the first current path in a circuit branch between the third capacitor and the second capacitor and the second current path in a circuit branch between the fourth capacitor and the first capacitor are interrupted.
4 . Power converter according to claim 1 , wherein
the central node is a common node
of the third terminal of the filter device,
a terminal of the first capacitor facing away from the third capacitor and/or facing the second capacitor, and
a terminal of the second capacitor facing away from the fourth capacitor and/or facing the first capacitor.
5 . Power converter according to claim 1 , wherein
the central node is connected to the third terminal of the filter device.
6 . Power converter according to claim 1 , wherein
the switching device has a first terminal and a second terminal and a switching path able to be controlled on the basis of the control information.
7 . Power converter according to claim 6 , wherein
the first terminal of the switching device has a common node with the first capacitor and the third capacitor and/or the second terminal of the switching device has a common node with the second capacitor and the fourth capacitor.
8 . Power converter according to claim 6 , wherein
the switching device is configured to switch on the switching path so as to adopt the first filter mode and/or to switch it off so as to adopt the second filter mode.
9 . Power converter according to claim 1 , wherein
the capacitances of the first capacitor and of the fourth capacitor are smaller or larger, in particular by a factor of at least two, in particular by a factor of at least five, than the capacitances of the second capacitor and the third capacitor.
10 . Power converter according to claim 1 , wherein
the capacitances of the first capacitor and the fourth capacitor are equal and/or the capacitances of the second capacitor and the third capacitor are equal.
11 . Power converter according to claim 1 , wherein
the filter device further has a fifth capacitor which is connected to the first terminal and to the second terminal of the filter device in parallel with the first to fourth capacitors and, in particular, has a capacitance larger, in particular at least by a factor of five, preferably a factor of ten, than the largest capacitance of the first to fourth capacitor.
12 . Power converter according to claim 1 , wherein
a fourth terminal of the filter device is the first terminal of the filter device or is connected to the first line, wherein
a fifth terminal of the filter device is the second terminal of the filter device or is connected to the second line, wherein
a sixth terminal of the filter device is the third terminal of the filter device or is connected to the third line, wherein
the filter device furthermore has
a sixth capacitor and a seventh capacitor, between which a second central node is formed with an electrically conductive connection to the sixth terminal,
an eighth capacitor, which is connected between a terminal of the sixth capacitor facing away from the second central node and the fourth terminal of the filter device,
a ninth capacitor, which is connected between a terminal of the seventh capacitor facing away from the second central node and the fifth terminal of the filter device, and
a second switching device that is configured to switch between a first filter mode and a second filter mode of the filter device depending on control information,
wherein
a third current path for the interference current is formed on the first line from the fourth terminal of the filter device via the eighth capacitor, a parallel connection of the sixth capacitor and the seventh capacitor and the second central node to the sixth terminal of the filter device, wherein
a fourth current path for the interference current is formed on the second line from the fifth terminal of the filter device via the ninth capacitor, a parallel connection of the sixth capacitor and the seventh capacitor and the second central node to the sixth terminal of the filter device, wherein
in the second filter mode, an admittance for the interference currents along the third current path and the fourth current path is at least reduced compared to the first filter mode.
13 . Power converter according to claim 12 , wherein
the capacitances of the sixth capacitor and of the ninth capacitor are greater, in particular by at least a factor of two, in particular by at least a factor of five, than the capacitances of the seventh capacitor and of the eighth capacitor, if the capacitances of the first capacitor and of the fourth capacitor are smaller than the capacitances of the second capacitor and of the third capacitor, or
the capacitances of the sixth capacitor and of the ninth capacitor are smaller, in particular by at least a factor of two, in particular by at least a factor of five, than the capacitances of the seventh capacitor and of the eighth capacitor, if the capacitances of the first capacitor and of the fourth capacitor are greater than the capacitances of the second capacitor and of the third capacitor.
14 . Power converter according to claim 1 , wherein
the filter device has a printed circuit board, wherein
the first to fourth capacitors in particular also the fifth capacitor and/or the sixth to ninth capacitors are arranged on the printed circuit board and/or
the first to third terminals of the filter device are arranged on the printed circuit board and/or
the switching device or the switching devices is arranged on the printed circuit board,
and/or
the power converter further comprises a DC link capacitor which is connected between the first line and the second line and in particular has a capacitance which is greater by at least a factor of one hundred, preferably a factor of five hundred, than the largest capacitance of the first to fourth capacitor, and a converter circuit, which is connected between the first line and the second line, wherein the filter device is arranged on the side of the DC link capacitor facing away from the converter circuit.
15 . On-board electrical system for an electrically driveable vehicle, having
at least one power converter according to claim 1 , a traction battery, a charging device that is able to be connected to an electrical power supply system external to the vehicle in order to charge or discharge the traction battery, and a control device that is configured to provide the control information to adopt the second filter mode when and/or for as long as the charging device is connected to the electrical power supply system external to the vehicle.
16 . Power converter according to claim 2 , wherein
in the second filter mode
the admittance along the first current path between the third capacitor and the second capacitor is at least reduced compared to the first filter mode and the admittance along the second current path between the fourth capacitor and the first capacitor is at least reduced compared to the first filter mode, or
the first current path in a circuit branch between the third capacitor and the second capacitor and the second current path in a circuit branch between the fourth capacitor and the first capacitor are interrupted.
17 . Power converter according to claim 2 , wherein
the central node is a common node
of the third terminal of the filter device,
a terminal of the first capacitor facing away from the third capacitor and/or facing the second capacitor, and
a terminal of the second capacitor facing away from the fourth capacitor and/or facing the first capacitor.
18 . Power converter according to claim 2 , wherein
the central node is connected to the third terminal of the filter device.
19 . Power converter according to claim 2 , wherein
the switching device has a first terminal and a second terminal and a switching path able to be controlled on the basis of the control information.
20 . Power converter according to claim 7 , wherein
the switching device is configured to switch on the switching path so as to adopt the first filter mode and/or to switch it off so as to adopt the second filter mode.