Transformer arrangement and method for voltage conversion including a transformer and a converter coupling
A transformer arrangement includes a first and a second arrangement side and a transformer with first windings coupled to the first arrangement side and with second windings having a first to a fourth tap. The transformer arrangement comprises a converter coupling the first, second and third tap to the second arrangement side, a first filter circuit coupling the first tap to the third tap and a second filter circuit coupling the third tap to the second tap.
1. A transformer arrangement, comprising,
a first and a second arrangement side,
a transformer with first windings coupled to the first arrangement side and with second windings having a first to a fourth tap,
a converter coupling the first, the second and the third tap to the second arrangement side,
a first filter circuit coupling the first tap to the third tap, and
a second filter circuit coupling the third tap to the second tap, wherein the converter comprises,
a first arm comprising a first number of cells and a first terminal connected to the first tap,
a second arm comprising a second number of cells and a first terminal connected to the second tap, and
a third arm comprising a third number of cells and a first terminal connected to the third tap, and
wherein the third number of cells is less than the first number of cells and is less than the second number of cells,
wherein the first arm comprises a first low frequency (LF) part and a first high frequency (HF) part,
wherein the second arm comprises a second LF part and a second HF part,
wherein the third arm comprises a third HF part,
wherein a first internal filter of the converter couples a node between the first LF part and the first HF part to a neutral point (NP), and
wherein a second internal filter of the converter couples a node between the second LF part and the second HF part to the neutral point (NP).
2. The transformer arrangement of claim 1 ,
wherein the transformer arrangement comprises an output of the filter circuit, and
wherein a second terminal of the first arm, a second terminal of the second arm and a second terminal of the third arm are coupled via the output filter circuit to a first terminal of the second arrangement side.
3. The transformer arrangement of claim 2 ,
wherein the output filter circuit includes a capacitive element connected to the third tap.
4. The transformer arrangement of claim 1 ,
wherein the first number of cells is equal to the second number of cells.
5. The transformer arrangement of claim 1 ,
wherein a cell comprises a device of a group comprising a metal-oxide-semiconductor field-effect transistor, an insulated-gate bipolar transistor, a thyristor and a bi-mode insulated gate transistor.
6. The transformer arrangement of claim 1 ,
wherein the first number of cells of the first arm include at least a cell of a first type and a cell of a second type, and
wherein the second number of cells of the second arm include at least a cell of a first type and a cell of a second type,
wherein the cell of the first type is configured for operation at higher frequencies as the cell of the second type.
7. The transformer arrangement of claim 1 ,
wherein the transformer arrangement comprises a by-pass switch coupling a first terminal of the second arrangement side to one tap of a group comprising the first, the second and the third tap.
8. The transformer arrangement of claim 1 ,
wherein the transformer arrangement comprises,
a box in which the converter is arranged, and
a tank in which the transformer and the box are arranged.
9. The transformer arrangement of claim 1 ,
wherein the transformer arrangement comprises,
a box in which the converter is arranged,
a tank in which the transformer is arranged, and
bushings that couple at least the first, the second and the third tap to the converter.
10. A transformer arrangement, comprising,
a first and a second arrangement side,
a transformer with first windings coupled to the first arrangement side and with second windings having a first to a fourth tap,
a converter coupling the first, the second and the third tap to the second arrangement side,
a first filter circuit coupling the first tap to the third tap, and
a second filter circuit coupling the third tap to the second tap, wherein the converter comprises,
a first arm comprising a first number of cells and a first terminal connected to the first tap,
a second arm comprising a second number of cells and a first terminal connected to the second tap, and
a third arm comprising a third number of cells and a first terminal connected to the third tap, and
wherein the third number of cells is less than the first number of cells and is less than the second number of cells,
wherein the converter comprises a fourth arm comprising a fourth number of cells and a first terminal connected to the third tap,
wherein a second terminal of the third arm is connected to a node of the first arm,
wherein a second terminal of the fourth arm is connected to a node of the second arm, and
wherein a second terminal of the first arm and a second terminal of the second arm are coupled to a first terminal of the second arrangement side,
wherein the node of the first arm is located between a first low frequency (LF) part of the first arm and a first high frequency (HF) part of the first arm, and
wherein the node of the second arm is arranged between a second LF part of the second arm and a second HF part of the second arm.
11. The transformer arrangement of claim 10 ,
wherein the first arm includes a first internal filter and the second arm includes a second internal filter.
12. A transformer arrangement, comprising,
a first and a second arrangement side,
a transformer with first windings coupled to the first arrangement side and with second windings having a first to a fourth tap,
a converter coupling the first, the second and the third tap to the second arrangement side,
a first filter circuit coupling the first tap to the third tap, and
a second filter circuit coupling the third tap to the second tap, wherein the converter comprises,
a first arm comprising a first number of cells and a first terminal connected to the first tap,
a second arm comprising a second number of cells and a first terminal connected to the second tap,
a third arm comprising a third number of cells and a first terminal connected to the third tap, and
wherein the transformer arrangement comprises an output filter circuit, and
wherein a second terminal of the first arm, a second terminal of the second arm and a second terminal of the third arm are coupled via the output filter circuit to a first terminal of the second arrangement side, and
wherein the output filter circuit includes a capacitive element connected to the third tap
wherein the first arm comprises a first low frequency (LF) part and a first high frequency (HF) part,
wherein the second arm comprises a second LF part and a second HF part,
wherein the third arm comprises a third HF part,
wherein a first internal filter of the converter couples a node between the first LF part and the first HF part to a neutral point (NP), and
wherein a second internal filter of the converter couples a node between the second LF part and the second HF part to the neutral point (NP).
13. A transformer arrangement, comprising,
a first and a second arrangement side,
a transformer with first windings coupled to the first arrangement side and with second windings having a first to a fourth tap,
a converter coupling the first, the second and the third tap to the second arrangement side,
a first filter circuit coupling the first tap to the third tap, and
a second filter circuit coupling the third tap to the second tap, wherein the converter comprises,
a first arm comprising a first number of cells and a first terminal connected to the first tap,
a second arm comprising a second number of cells and a first terminal connected to the second tap,
a third arm comprising a third number of cells and a first terminal connected to the third tap,
wherein the filter circuitry includes a capacitive element connected to the third tap,
wherein the transformer arrangement comprises an output filter circuit,
wherein a second terminal of the first arm, a second terminal of the second arm and a second terminal of the third arm are coupled via the output filter circuit to a first terminal of the second arrangement side, and
wherein the converter comprises a fourth arm comprising a fourth number of cells and a first terminal connected to the third tap,
wherein a second terminal of the third arm is connected to a node of the first arm,
wherein a second terminal of the fourth arm is connected to a node of the second arm, and
wherein a second terminal of the first arm and a second terminal of the second arm are coupled to a first terminal of the second arrangement side,
wherein the node of the first arm is located between a first low frequency (LF) part of the first arm and a first high frequency (HF) part of the first arm, and
wherein the node of the second arm is arranged between a second LF part of the second arm and a second HF part of the second arm.
14. The transformer arrangement of claim 13 ,
wherein the first arm includes a first internal filter and the second arm includes a second internal filter.
15. The transformer arrangement of claim 14 ,
wherein the first number of cells is equal to the second number of cells.
16. The transformer arrangement of claim 15 ,
wherein a cell comprises a device of a group comprising a metal-oxide-semiconductor field-effect transistor, an insulated-gate bipolar transistor, a thyristor and a bi-mode insulated gate transistor.