Accurate Transient Thermal Analysis for Ferrite-Based Wireless Power Transfer Coupler Using Double-D Coil

Temperature is a vital operation parameter affecting the stability and reliability of the wireless power transfer (WPT) system. This paper conducts an accurate transient thermal analysis for the WPT double-D magnetic coupler, covering power loss measurements for the coil and the magnetic core. In this work, an automated interactive tool is developed to achieve fast thermal modeling and transient analysis. To enhance the simulation accuracy and efficiency of the numerical model, geometric segmentation modeling and homogenization modeling are employed for the magnetic core and the coil, respectively. To achieve accurate loss calculation in numerical simulation, a measurement scheme based on the equal power method is proposed to indirectly measure the AC resistance of the coil, and the core losses are extracted from the AC-AC losses of the WPT system, which comprehensively considers the effects of core geometric shape and current harmonics. Finally, experimental measurements, including tests at power levels up to 5.2 kW and under coil misalignment conditions, are conducted to validate the numerical model. The results demonstrate that under transient conditions, the numerical model achieves a maximum error of only 4.2% with calibration and 6.0% without calibration.