Analysis of rotor overhang effect in BLDC fan motor for vehicle considering load torque variance

This paper deals with the characteristic analysis of the fan motor considering ferrite bonded magnet in an inner-rotor overhang type Brushless DC motor. In many case of output characteristics analysis, the rotor overhang is neglected because of using 2D FEA (Finite Element Analysis). For this, 3D FEA should be required, but 3D FEA requires very long calculation time even though high specification computer is used. This paper presents the characteristics analysis method considering rotor overhang flux by using 2D FEA. The 3D electromagnetic model of BLDC motor is approximated as the 2D electromagnetic model considering overhang effect. For this, the concept of overhang coefficient is applied. The validity of the analysis method is verified by comparing the analyzed results with 3D FEM.