Rotational Core Loss of Silicon Steel Laminations Based on Three-Dimensional Magnetic Properties Measurement

Magnetic properties of silicon steel laminations are important features in power transformer and electrical machine design and manufacture. Conventional testing methods such as Epstein Frame and Single Sheet Tester may only consider one direction or one sheet, which may deviate from the real application, particularly in core loss calculation. A 3-D magnetic properties' testing method is proposed in this paper. By using the designed special surface B-H sensing coils, the dynamic magnetic hysteresis properties of a laminated non-grain-oriented silicon steel sample are accurately measured. The relationship between B and H in alternating, 2-D rotational, and 3-D spherical rotational excitations, from 50 to 200 Hz, is studied and analyzed. In order to control the B waveform better, the harmonics of B_x and B_y signals are analyzed at 50 Hz. The alternating core losses in the rolling, transverse, and laminated directions and the rotational core losses in the xoy plane of this sample at 50, 100, and 200 Hz are calculated and analyzed. Moreover, the core losses in the three directions are well predicted by means of total core loss separation theory.