Experimental Evaluation of High-Frequency Magnetization Characteristics of Core Materials

Aircraft and many other on-board applications require compact electric motor drives having high power densities. A typical motor drive includes an electrical machine controlled by a power-electronic converter. Ferromagnetic materials form an important part of such machines and integrated magnetics in power converters. Hence the knowledge of such materials at operating conditions of frequency and flux density is crucial in the electromagnetic and thermal design of such systems. The information in manufacturers’ datasheets is limited and typically available at conventional frequencies like 50 Hz. However, operating frequencies in such motor drives can extend upto hundreds and thousands of Hz. Hence, in-house characterization of magnetic materials becomes necessary over the frequency range of interest. In this paper, two SiFe steels- 50C600 and 50C800 are characterized over a frequency range of 333 Hz to 1000 Hz, and upto flux densities of around 1.5 T. Experimental B-H loops are obtained at different frequencies and compared. Detailed procedure for evaluation of magnetization and core-loss curves from multiple B-H loops is provided. Core-losses at working levels of flux-densities are observed to be much higher at higher frequencies. The experimental data obtained, can be used in the design and analysis of magnetic structures fabricated using such materials.