Performance Factor Comparison of Nanocrystalline, Amorphous, and Crystalline Soft Magnetic Materials for Medium-Frequency Applications

The efficiency of electromagnetic devices is influenced by the losses of the applied soft magnetic material. Different structured materials are available. Choosing the most appropriate material for a medium-frequency application is not intuitive. Electromagnetic circuits of power transformers or electric motors are usually made of conventional silicon-iron sheets. Higher power densities can be achieved by an increased operational frequency, but the loss density increases with higher frequencies as well. Amorphous and nanocrystalline materials benefit from reduced eddy current losses at higher frequencies. In this paper, a performance factor is evaluated to determine the suitability of each material in a frequency range up to 10 kHz. The geometric parameters of electromagnetic designs depend on the applied material. A performance factor may help to identify the most appropriate material at a specific frequency. The final application is a medium-frequency transformer. The losses of the magnetic materials are measured by using standardized measurement equipment such as single sheet tester or Epstein frame. A semi-physical iron-loss model is used to describe the measured losses. These results are used to determine the performance factor.