The saturation temperature of liquefied natural gas(LNG)is -161 ℃

and the losses generated by the pump motor used to transport LNG increase its heat generation

which can easily lead to LNG vaporization. The iron core material of motors is usually made of silicon steel sheets. Traditional low silicon silicon steel sheets(3% Si)have increased iron core loss in ultra-low temperature environments compared to room temperature

which is not conducive to suppressing the heating of motors. In response to the above issues

the loss characteristics of low silicon steel sheets and high silicon steel sheets(6.5% Si)in ultra-low temperature environments were compared and studied. Through testing experiments at different temperatures

the law of loss variation of high silicon steel sheets with temperature was studied. The results show that high silicon steel sheets are more suitable for ultra-low temperature motors. Based on the loss characteristics of high silicon steel sheets in ultra-low temperature environments

a variable temperature core loss calculation model for high silicon steel sheets in ultra-low temperature environments by introducing temperature coefficients and correction factors was established. The accuracy of the model was verified by comparing the measured values and model calculated values under different magnetic densities and frequencies.