Planar resonant multi-output transformer for printed circuit board integration

A converter with printed circuit board integrated transformer to supply 16 similar isolated loads is designed and manufactured. The transformer of the power converter is constructed as planar device consisting of printed circuit board spiral windings and ferrite polymer compound plates as magnetic core, which can be laminated to the printed circuit board. The design consists of one large primary spiral winding. On top of the primary winding, secondary spiral windings are arranged side by side, such that a portion of the primary flux penetrates each secondary winding. A well-defined part of the primary winding is not covered by the secondary windings leading to a series inductivity as a matching impedance. Each secondary winding is covered by a sensing winding. As a unique feature, it results in a significant height reduction of the electronic circuit. Furthermore it allows an approximately load independent output power and a fault detection for each individual output without the need for a feedback from the secondary side. An efficiency of up to 81% could be measured.