Nanocrystalline Power Loss and Thermal Mitigation for 11.1 kW Inductive Power Transfer Pads: A Novel Frequency-Dependent Optimization

Nanocrystalline pads are normally considered to be infeasible in inductive power tansfer (IPT) systems due to their excessive loss - thermal behavior. This article proposes a novel frequency-dependent optimization method, for core loss reduction and thermal mitigation within nanocrystalline pads designed for high-power density IPT systems. To explore the applicability of nanocrystalline in an IPT system with a wide operating frequency range, the characteristics of traditional and crushed nanocrystalline are measured and analyzed within a frequency range of 10-500 kHz by a testing platform. It is found that the crushing process will result in the increased loss of nanocrystalline in specific frequency ranges. This interesting phenomenon is different from what is expected and can be further explained by the delicate balance among core loss contributions affected by crushing. As a result, its frequency dependence rule is found. Based on the frequency-dependent rule, an optimization method is proposed to mitigate the power loss and thermal behavior of nanocrystalline pads, and is successfully applied to the simulation model and 11.1 kW level IPT full-scale prototype at the defined operating frequency range. Simulation and experimental results show that compared with traditional nanocrystalline pads, the power loss of the optimized pads is reduced by 27.2% and thermal mitigation by 50%. It is demonstrated that the high-power density IPT system using the optimized pads with frequency dependency achieves an excellent performance which is superior to the system using traditional nanocrystalline pads.