Effects of High-frequency Operation on Magnetic Components in Power Converters

Compound semiconductor devices such as Gallium Nitride (GaN) and Silicon Carbide (SiC) are actively adopted in power converters to improve power conversion efficiency, downsize passive components and miniaturize cooling systems. However, in the power converters, magnetic components often become bottlenecks in power converters from size, power losses, and temperature rise perspective. Therefore, in some cases, the attractive performance of GaN and SiC cannot be fully utilized due to the limits imposed by magnetic components. To indicate this matter from an experimental perspective, this paper conducts a fundamental investigation of the downsizing effect of magnetic components and temperature rise when varying switching frequency (85 kHz, 150 kHz, 350 kHz, 1 MHz) of a 1 kW boost converter as a case study. As results of experiments, although high-switching frequency operation contributes to downsizing magnetic component effectively, the thermal runaway of the magnetic core while driving at high frequency is confirmed due to downsized small surface area and increasing iron loss due to temperature dependency of Mn-Zn ferrite magnetic cores. For a fair comparison, the area product approach is used in the design procedure for selecting core size. The effect of the high-frequency drive is discussed from theoretical and experimental viewpoints.