Core Loss Estimation of Various Materials Magnetized With the Symmetrical/Asymmetrical Rectangular Voltage

Core losses were estimated for various magnetic core materials magnetized with a duty-cycle-changed symmetrical and asymmetrical rectangular voltage. Each voltage waveform is applied to a transformer and a dc reactor in a dc/dc converter, respectively. Core losses were measured for the four typical magnetic core materials often used in power electronics: 3% grain-oriented silicon steel sheet, 6.5% silicon steel sheet, amorphous material, and nanocrystalline material. Measurement results were evaluated by the loss separation model. An approximation method was proposed for the core loss magnetized with asymmetrical rectangular voltage that divides the total core loss into the core loss of the magnetization from -B_m to B_m and that of the magnetization from B_m to -B_m. This method was confirmed to approximate the core loss accurately except for silicon steel sheet in an extreme duty cycle condition. However, it was demonstrated experimentally that dc component of the magnetic field strength caused this error.