Temperature influence on core losses and magnetization demand of electrical steel sheets using adapted Epstein frame and ring probe

In this paper, the influence of temperatures up to 250 °C on core losses and magnetization demand of electrical steel sheets is illustrated. Therefore, measurements are made using an adopted high-temperature Epstein frame and a stator core as a ring probe. Three different electrical steel sheet grades, M330-50A, M530-50A and NO20-15, and a stator core are tested. Magnetic property measurements are performed at various frequencies from DC to 1.2 kHz with a defined sinusoidal waveform of magnetic polarization. This covers a wide range of electric motor applications from industrial drives to electric vehicle drives. With increasing temperature, magnetization demand rises significantly in medium polarization range. For specific core losses, a loss separation is performed using the Jordan approach, separating specific hysteresis and specific eddy current losses to determine the temperature influence on each loss component. The temperature behavior of the specific electrical resistivity of electrical steel sheets is measured and used to calculate the physical specific eddy current losses. After separation, specific hysteresis losses also show a significant temperature influence.