EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

B-H hysteresis loops represent essential information for engineering applications such as the design of efficient electric engines and induction heating processes in the steel industry. Modern simulation techniques can reduce development times for industrial processes and components but they rely on proper material data. Electromagnetic simulations require data for B-H hysteresis loops that are free of eddy current effects. Depending on the measurement conditions, this can be a challenging limitation both for the measurement technique itself and for the usability of the measured data. For the measurement of temperature dependent B-H hystereses, sufficiently high frequencies in the order of at least 1 Hz have to be applied in order to guarantee a constant temperature field within the sample. In a current study, a cylindrical sample geometry with Ø22x300 was used, which can be directly measured in an induction heating facility. The induction system can be employed to perform incremental heating up to Curie temperature, while synchronized electromagnetic excitation for material characterization is performed with a separate system. In this setup, measurement frequencies in the order of 0.01 Hz do not cause distortion of the B-H hysteresis due to eddy currents, but using 1 Hz, eddy current effects are clearly present. The main topic of this work is the conversion of the form of a B-H hysteresis obtained under measurement conditions, where eddy currents are affecting the magnetisation during the electromagnetic excitation, to the low frequency hysteresis. To address these challenges, a semi-empirical B-H hysteresis conversion model was developed based on the induction law and the field diffusion equation in a medium. This model makes it possible to convert a B-H hysteresis measured at a higher frequency into its characteristic shape at a lower frequency, with a small influence of the eddy currents.