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Winding Techniques

D11.11 - Flatwise Windings for Improved Thermal Management in High Power Transformer Applications

Thursday, March 26, 2026
12:00 PM - 1:45 PM CT
Location: Hemisfair Ballroom
Effective thermal management is one of the primary design bottlenecks for high-power transformers. While rectangular windings offer high fill factors and current capabilities, research comparing the thermal and electrical characteristics of different winding orientations remains limited. This paper proposes a low-profile transformer utilizing flatwise windings, characterized by rectangular conductors stacked radially from their broad face. This configuration creates a fundamentally lower thermal resistance path by enabling direct, simultaneous, and parallel heat extraction from every turn. A thermomagnetic FEA comparing the proposed design against a traditional edgewise structure at 1 kW demonstrates a peak temperature reduction of 10.9◦C under natural cooling and 13.4◦C under forced air cooling. The results confirm that the proposed flatwise-wound transformer ensures a uniform heat distribution. These results validate the superior thermal performance of the flatwise structure, enabling more compact, power-dense transformers. Furthermore, a comprehensive design methodology and trade-off analysis for the proposed transformer are presented.