Fractional turns transformers with ferrite polymer core

• US 20070030107A1
• Filed: 08/24/2004
• Published: 02/08/2007
• Est. Priority Date: 09/04/2003
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Dürbaum, Thomas, Waffenschmidt, Eberhard
• Granted Patent: US 7,915,991 B2
• Time in Patent Office: Days
• US Class Current: 336/200
• CPC Class Codes: H01F 1/37 in a bonding agent
• CPC Class Codes: H01F 2017/048 with encapsulating core, e.g. made of resin and magnetic powder
• CPC Class Codes: H01F 27/2804 Printed windings
• CPC Class Codes: H01F 41/046 structurally combined with ferromagnetic material
• CPC Class Codes: H05K 1/165 incorporating printed inductors
• CPC Class Codes: H05K 2201/086 for inductive purposes, e.g. printed inductor with ferrite core
• CPC Class Codes: H05K 2201/09063 Holes or slots in insulating substrate not used for electrical connections
• CPC Class Codes: H05K 2203/1572 Processing both sides of a PCB by the same process; Providing a similar arrangement of components on both sides; Making interlayer connections from two sides
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49073 by assembling coil and core

Abstract

Conventional transformers with ractional turns have pre-manufactured cores usually with a complicated structure. According to the present invention, a method is provided of manufacturing a planar transformer where a ferrite polymer compound is laminated to a PCB for forming the core of the transformer. Advantageously, this may allow for the provision of a cheap and robust transformer.

Claims

1. Method of manufacturing a transformer, the method comprising the steps of:

providing a printed circuit board having at least one conductive layer, wherein the printed circuit board has an upper side and a lower side;

forming a primary winding and a plurality of secondary windings on the printed circuit board by structuring the at least one conductive layer;

laminating a ferrite polymer compound to the upper and lower sides of the printed circuit board for forming a core of the transformer.

2. The method of claim 1, wherein the ferrite polymer compound is unstructured.

3. The method of claim 1, wherein first recesses are formed in the printed circuit board;

wherein the ferrite polymer compound is laminated to the printed circuit board such that after lamination, the ferrite polymer compound fills the first recesses and covers at least parts of the upper and lower sides of the printed circuit board.

4. The method of claim 3, wherein the primary winding surrounds the plurality of secondary windings which are provided in an inner area of the primary winding such that a fractional winding turn is formed;

wherein each first recess is surrounded by at least one of the plurality of secondary windings.

5. The method of claim 4, wherein the primary winding surrounds a first number secondary windings;

wherein a second number of first recesses is provided in the printed circuit board;

wherein each of the first recesses is surrounded by at least one of the secondary windings;

wherein the first number corresponds to the second number;

wherein second recesses are formed on sides of the primary winding outside of the inner area;

wherein the ferrite polymer compound is laminated to the printed circuit board board such that it fills the second number of first recesses and the second recesses and at least parts of the upper and lower sides of the printed circuit board to form the core;

wherein the arrangement of the primary and secondary windings and the core is such that during operation of the planar transformer, a flux trough the primary winding is split into a third number of paths;

wherein the third number corresponds to the first number and the second number.

6. Transformer, comprising:

a printed circuit board, wherein the printed circuit board has an upper side and a lower side;

wherein a primary winding and a plurality of secondary windings are formed on the printed circuit board; and

a ferrite polymer compound laminated to the upper and lower sides of the printed circuit board for forming a core of the transformer.

7. The transformer of claim 6, wherein first recesses are provided in the printed circuit board;

wherein the ferrite polymer compound is laminated to the printed circuit board such that after lamination, the ferrite polymer compound fills the first recesses and covers at least parts of the upper and lower sides of the printed circuit board.

8. The transformer of claim 7, wherein the primary winding surrounds the plurality of secondary windings which are provided in an inner area of the primary winding such that a fractional winding turn is formed;

wherein each first recess is surrounded by at least one of the plurality of secondary windings.

9. The transformer of claim 8, wherein the primary winding surrounds a first number secondary windings;

wherein a second number of first recesses is provided in the printed circuit board;

wherein each of the first recesses is surrounded by at least one of the secondary windings;

wherein the first number corresponds to the second number;

wherein second recesses are formed on sides of the primary winding outside of the inner area;

wherein the ferrite polymer compound is laminated to the printed circuit board such that it fills the second number of first recesses and the second recesses and at least parts of the upper and lower sides of the printed circuit board to form the core;

wherein the arrangement of the primary and secondary windings and the core is such that during operation of the planar transformer, a flux trough the primary winding is split into a third number of paths;

wherein the third number corresponds to the first number and the second number.

10. The transformer of claim 6, wherein the transformer has fractional turns.

11. The transformer of claim 6, wherein the plurality of secondary windings are connected in parallel.