Electrical transformer and method of manufacturing an electrical transformer

1. An electrical transformer, comprising:

a set of primary windings comprising first and second primary windings connected in parallel; and

first and second sets of secondary windings, each of the first and second sets comprising a plurality of secondary windings that are connected in parallel, the secondary windings of the first set being electrically isolated from the secondary windings of the second set,

wherein the set of primary windings and the first and second sets of secondary windings are arranged in a stacked structure in which:

the secondary windings of the first set alternate with and are interleaved with the secondary windings of the second set, and

at least one secondary winding of the first set and/or at least one secondary winding of the second set is arranged between the first and second primary windings.

2. The electrical transformer according to claim 1 , wherein the at least one secondary winding of the first set and the at least one secondary winding of the second set are both arranged between the first and second primary windings.

3. The electrical transformer according to claim 1 , wherein at least one secondary winding of the first set is connected in series with a secondary winding of the second set.

4. The electrical transformer according to claim 1 , wherein every secondary winding of the first set is connected in series with a respective secondary winding of the second set.

5. The electrical transformer according to claim 1 , wherein the first set and the second set each comprise three secondary windings that are connected in parallel.

6. The electrical transformer according to claim 1 , wherein the first primary winding is arranged between a first winding group and a second winding group, and the second primary winding is arranged between the second winding group and a third winding group, each of the first, second and third winding groups comprising one or more secondary windings of the first set and one or more secondary windings of the second set.

7. The electrical transformer according to claim 1 , wherein each of the secondary windings of the first and second sets comprises 2 turns.

8. The electrical transformer according to claim 1 , wherein each of the secondary windings of the first and second sets comprises at least one busbar.

9. The electrical transformer according to claim 1 , wherein each of the first and second primary windings comprises 18 turns.

10. The electrical transformer according to claim 1 , wherein each of the first and second primary windings comprises at least one Litz wire.

11. The electrical transformer according to claim 1 ,

wherein each secondary winding of the first set has a first output connector for connecting to a first transformer output,

wherein each secondary winding of the second set has a second output connector for connecting to a second transformer output, different to the first transformer output, and

wherein each secondary winding of the first and second sets has a third output connector for connecting to a third transformer output, the third transformer output being different to each of the first transformer output and the second transformer output.

12. The electrical transformer according to claim 11 , wherein each of the first transformer output, second transformer output and third transformer output comprises a busbar.

13. The electrical transformer according to claim 1 , comprising a polymer layer disposed on a surface of a secondary winding of the first set and/or of the second set.

14. A battery pack equipment for an electrically powered vehicle, the battery pack equipment comprising at least one rechargeable battery and the electrical transformer according to claim 1 .

15. The electrical transformer according to claim 1 , wherein each of the secondary windings of the first and second sets comprises at least two busbars.

16. A method of manufacturing an electrical transformer, the method comprising:

providing a set of stackable primary windings comprising first and second primary windings;

providing a plurality of stackable secondary windings;

grouping the plurality of secondary windings into a first set of secondary windings and a second set of secondary windings;

stacking the set of primary windings and the first and second sets of secondary windings;

connecting the first and second primary windings of the set of primary windings in parallel;

connecting the secondary windings of the first set in parallel; and

connecting the secondary windings of the second set in parallel,

wherein the set of primary windings and the first and second sets of secondary windings are stacked such that:

the secondary windings of the first set alternate with and are interleaved with the secondary windings of the second set, and

at least one secondary winding of the first set and/or at least one secondary winding of the second set is arranged between the first and second primary windings.

17. A wireless power transfer (WPT) system comprising a primary side and a secondary side, the secondary side of the WPT system comprising an electrical transformer, the electrical transformer comprising:

a set of primary windings comprising first and second primary windings connected in parallel; and

first and second sets of secondary windings, each of the first and second sets comprising a plurality of secondary windings that are connected in parallel, the secondary windings of the first set being electrically isolated from the secondary windings of the second set,

wherein the set of primary windings and the first and second sets of secondary windings are arranged in a stacked structure in which:

the secondary windings of the first set alternate with and are interleaved with the secondary windings of the second set, and

at least one secondary winding of the first set and/or at least one secondary winding of the second set is arranged between the first and second primary windings.