High-frequency transformers using solid wire for welding-type power supplies

A welding-type power supply transformer, comprising:

• a first coil assembly comprising a first plurality of turns of a first solid wire wrapped around a first bobbin to form a first single-layer primary winding, and a second plurality of turns of a second conductor over the first plurality of turns to form a first single-layer secondary winding, wherein the first solid wire comprises solid magnet wire, extruded aluminum, or rolled aluminum;
• a second coil assembly comprising a third plurality of turns of a second solid wire wrapped around a second bobbin to form a second single-layer primary winding, and a fourth plurality of turns of the second conductor over the third plurality of turns to form a second single-layer secondary winding;
• first and second cores disposed at least partially within the first and second bobbins, wherein the first ferrite core comprises a first U-core and the second ferrite core comprises a second U-core, the first and second U-cores configured to be inserted into each of the first and second bobbins, and the first and second ferrite cores and the first and second bobbins have obround cross-sections;
• a tertiary winding wound around a bridge portion of the first U-core;
• a shading ferrite configured to increase a leakage inductance of the tertiary winding;
• and
• polyethylene terephthalate (PET) tubing around at least portions of the first and second secondary windings that are adjacent the first and second primary windings;
• wherein the secondary winding comprises extruded aluminum or extruded copper.