Prospects for advances in power magnetics

Inductors and transformers are critical for high-efficiency power conversion. Increased frequency can, in principle, reduce their size and power losses, but high-frequency loss effects make this hard to realize in practice. In windings, proximity effect is the most severe challenge. State-of-the-art techniques for reducing proximity effect are reviewed. Research addressing effective utilization of parallel thin foil layers and current balancing in very large litz-wire bundles is discussed. Magnetic materials for kHz and MHz frequencies are evaluated using performance factor and modified performance factor to account for high-frequency winding loss. Results indicate opportunities for continued miniaturization of power converters using frequencies above 2 MHz with continued research.