Calculation method and sensitive frequency of irradiation electromagnetic interference for axial flow fan

This study investigates the induced current characteristics and sensitive frequency of axial flow fans under an electromagnetic irradiation environment. Based on the Agrawal model and BLT equations, a frequency-domain analytical calculation method of induced current for nonlinear loads is proposed through winding impedance measurement and equivalent circuit modeling. The accuracy and efficiency are also verified using numerical methods. By analyzing the sensitive frequency of the transmission line, it is found that the induced current increases significantly at specific frequencies. Test results show that the axial flow fan is susceptible to exterior electromagnetic interference at the sensitive frequency points of 31 MHz and 93 MHz. The research results can provide a reference for the prediction and protection from the irradiation of electronic equipment.