Magnetic anisotropy investigation of grain-oriented electrical steels for a wide range of temperatures

Grain oriented electrical steel (GOES) has the advantages of high permeability, low iron loss and high saturation flux density in the rolling direction (RD). In practical, the magnetic field is not ideally in the direction of RD when the GOES is really operating. Therefore, a comprehensive insight into the magnetic anisotropy of GOES can help researchers to better utilize GOES. In addition, energy losses in electrical equipment and ambient temperatures can cause GOES to operate over a variable temperature. In order to design electrical equipment precisely, it is necessary to investigate the effect of temperature on the magnetic anisotropy of GOES. In this paper, the magnetic properties of GOES such as magnetic flux density, specific core loss, permeability, etc. are investigated at different temperatures and magnetization angles by experimental and theoretical analysis. The results show that the temperature has a significant effect on the magnetic anisotropy of GOES. The increase of temperature will increase the magnetic flux density and permeability in the unsaturated state, which is the most obvious in the range of easy magnetization angle. In the saturated state, an increase in temperature causes a decrease in flux density and permeability at the easy magnetization angle, i.e., in the range of 0°–30°, and the opposite law occurs at the difficult magnetization angle, i.e., in the range of 50°–70°. Similar to the properties of non-grain oriented electrical steel, an increase in temperature causes a decrease in iron loss, and their pattern of change is minor in relation to the magnetic anisotropy, and the reason for the decrease is the hysteresis loss and eddy current loss reduction. This paper reveals the relationship between magnetic anisotropy and temperature, and proves that the sensitivity of magnetic flux density and permeability to temperature is related to magnetization. The research content is not only of great significance to the cognition of material properties, but also can guide the design and performance prediction of electrical equipment.