A planar transformer includes a primary coil layer, a secondary coil layer, and a shielding layer. The shielding layer is disposed between the primary coil layer and the secondary coil layer. A primary coil is disposed in the primary coil layer, and a secondary coil is disposed in the secondary coil layer. The shielding layer includes a shielding coil with one end connected to a first static electrical point and the other end suspended, and an auxiliary winding with one end connected to a second static electrical point. The auxiliary winding supplies power to a functional circuit of the planar transformer. The winding direction of the shielding coil is opposite to the winding direction of the secondary coil; the winding direction of the auxiliary winding is the same as the winding direction of the secondary coil.

A system and method for wireless charging a wireless earbud. The wireless earbud having a body that includes a passive magnetic shield and a coil. The coil is wound around a portion of the body comprising the passive magnetic shielding. The wireless earbud receiving wireless energy in response to the placement of the body within an electromagnetic field, which results in the charging of a battery of the wireless earbud.

A magnetic structure in a power converter includes at least two multilayer boards, such as a primary board containing the primary windings and some auxiliary windings, and a secondary board containing the secondary windings and some auxiliary windings. The primary and secondary boards are on top of each other. On the layer on the primary bard adjacent to the secondary board, is a dual function shield to reduce the total common mode noise in the converter towards zero. The controlled dual function shield can be placed on the secondary board on the layer adjacent to the primary board, and in some embodiments can be placed on both primary and secondary board on the layers adjacent to the other board. The embodiments herein offer a very good solution for cost reduction of the planar transformers and offers an avenue for total elimination of the common mode noise in a power converter.

A system and method for wireless charging a wireless earbud. The wireless earbud having a body that includes a passive magnetic shield and a coil. The coil is wound around a portion of the body comprising the passive magnetic shielding. The wireless earbud receiving wireless energy in response to the placement of the body within an electromagnetic field, which results in the charging of a battery of the wireless earbud.

A planar transformer, a power conversion circuit, and an adapter, is provided to improve noise suppression performance. The planar transformer includes a magnetic core and a printed circuit board (PCB) winding board, where the PCB winding board includes a primary winding, a secondary winding, a shielding winding, and a compensation winding. In embodiments of this disclosure, the shielding winding and the compensation winding that has a plurality of turns of coils are disposed between the primary winding and the secondary winding of the planar transformer. The shielding winding can shield electric field coupling between the primary winding and the secondary winding, thereby suppressing a noise current between the primary winding and the secondary winding. Common mode noise generated by the compensation winding cancels common mode noise flowing to the secondary winding or the primary winding, to minimize common mode noise of an entire system.

A magnetic field generator includes a first planar substrate, a second planar substrate positioned opposite to the first planar substrate and separated from the first planar substrate by a gap, a first wiring set on the first planar substrate, a second wiring set on the second planar substrate, and one or more interconnects between the first planar substrate and the second planar substrate. The one or more interconnects electrically connect the first wiring set with the second wiring set to form a continuous electrical path. The continuous electrical path forms a conductive winding configured to generate, when supplied with a drive current, a first component of a compensation magnetic field configured to actively shield a magnetic field sensing region located in the gap from ambient background magnetic fields along a first axis that is substantially parallel to the first planar substrate and the second planar substrate.

A magnetic field concentrating or guiding device can include one or more coils, and one or more foil, tape and/or bulk superconductor structures disposed in one or more predetermined positions with relation to the coils. The one or more superconductor structures can form one or more magnetic field carrying regions. During operation, current passing through the one or more coils can generate one or more magnetic fields that are compressed or guided in the magnetic field carrying regions.

The primary coil assembly, which includes a primary coil interposed between a pair of secondary coils and configured to perform electromagnetic mutual induction, and includes: a bonding coil having both ends connected to primary-side terminal pins of the transformer; a first PCB member provided on an upper surface of the bonding coil and configured to constitute an upper-side auxiliary winding of the primary coil; and a second PCB member provided on a lower surface of the bonding coil and configured to constitute a lower-side auxiliary winding of the primary coil.

A system and method for wireless charging a wireless earbud. The wireless earbud having a body that includes a passive magnetic shield and a coil. The coil is wound around a portion of the body comprising the passive magnetic shielding. The wireless earbud receiving wireless energy in response to the placement of the body within an electromagnetic field, which results in the charging of a battery of the wireless earbud.

A device for reducing high-frequency interferences between first and second windings of a transformer that includes a first winding (W.sub.1) and a second winding (W.sub.2), which are wound around a common core, wherein the first winding (W.sub.1) is an interference-emitting winding and a shielding winding (W.sub.S) or a shielding film (W.sub.S) is arranged between the first winding (W.sub.1) and the second winding (W.sub.2), wherein the shielding winding (W.sub.S) and the core are connected to the reference potential (B) of the first winding (W.sub.1).