Lumped Thermal Model for Magnetic Components in an Interleaved DC–DC Converter

Magnetic component design is one of the key challenges for high-frequency DC-DC converters. Simple loss-based thermal analysis can be an alternative to achieving an effective electrothermal design for magnetics at the initial design stage, before the real prototype design, which can save cost and time. In this paper, a lumped thermal equivalent circuit (LTEC) model is developed to guide the thermal design of magnetic components. LTEC models are compared with finite element analysis (FEA) and experimental results. To capitalise on the amorphous core in designing high-current/high-frequency magnetic components, a physics-based analytical thermal model can be used to identify temperatures at specific nodes or points of interest. This lumped parameter-based method can be used for quick analysis and design optimisation, whereas FEA is better for identifying accurate temperature distribution and hot-spot temperatures and to guide the designers to achieve effective thermal design by adopting appropriate strategies such as potting or liquid cooling. This paper investigates two magnetic components in a high-frequency, interleaved DC-DC converter: one is the high current filter inductor, and the other is the interphase transformer (IPT). Both LTEC and FEA models are validated using experimental measurements from a 1.5 kW interleaved DC-DC converter prototype. The proposed LTEC results are comparable to both experimental and FEA results, and for the inductor, the average error is limited to 7.4% while for the IPT transformer average error is up to 5.7%.