Motor Design and Characteristics Comparison of Outer-Rotor-Type BLDC Motor and BLAC Motor Based on Numerical Analysis

In this study, we dealt with the design and characteristics of an outer-rotor type motor applied for the blower system of a vehicle according to a brushless dc motor (BLDCM) and a brushless ac motor (BLACM) through finite element analysis (FEA). In order to guarantee proper back electromotive force (BEMF) waveforms for each model, 8-pole/12-slot and 16-pole/12-slot types were applied to a BLDCM and a BLACM, respectively. Furthermore, we designed and analyzed all models based on a 3-D FEA to consider the 3-D effect of the end-plate of the rotor core. As a result, the BLACM was verified as having an advantage in the reduction of torque ripple and motor size, under identical current density conditions, considering the driving method. Finally, we suggest a 4-parallel delta-winding for a 12-slot motor to improve the winding usability.