Measurement of magnetic properties of grain-oriented electrical steel under bending stress in a wide frequency range

To clarify the mechanism of the magnetic properties deterioration and the increasing loss of the Grain-Oriented (GO) electrical steel wound cores under serving conditions, the effect of the bending stress in a wide frequency range should be thoroughly investigated. In this paper, a magnetic properties measuring system for GO electrical steel under different bending stress from 50 Hz to 1000 Hz is proposed. To ensure the accuracy and reproductivity of the measurements, the waveform of magnetic flux densities should be controlled to be sinusoidal. However, the bending stress aggravates the material’s nonlinear properties, making waveform control very difficult. To solve this problem, a frequency-domain adaptive dual-loop feedback control algorithm is developed. Obtained results show that the proposed method has a good effect on waveform control under bending stress, and the loss of the material under different magnetizing conditions is then analyzed.