Application of Highly Saturated Flexible Nanocrystalline Core in Wireless Charging of Electric Vehicles

Abstract:

To solve the problem that the ferrite core is easy to be saturated and has a poor mechanical performance in high power applications， a novel flexible high-saturation nanocrystalline core is adopted. However， due to low resistivity， nanocrystalline has a strong eddy current in the 85 kHz alternating electromagnetic field. To reduce the eddy loss， a refinement crushing process and an alternating seamless stitching process are proposed. Based on finite element simulation analysis， the feasibility of the modified process has been preliminarily proved. Four schemes of nanocrystalline cores with different permeabilities are compared with ferrite. The static parameter analysis and 7.7kW power transfer test indicate that the modified nanocrystalline cores perform well. Moreover，the nanocrystalline core with the best performance is adopted for anti-saturation test and leakage measurement at 11kW. Even when its thickness is decreased to 2mm， the AC-AC efficiency is still 97.408%. The maximum temperature of core is only 80.9℃， and flux leakage completely meets the limit requirements of ICNIRP 2010. In contrast， the ferrite core cannot withstand the action of a strong alternating field and is broken.

Key words:electric vehicles;wireless charging system;nanocrystalline core;finite element simulation;anti-saturation test