Design and Comparison of Radial Flux and Axial Flux Brushless DC Motors for Power Tool Applications

This paper presents a comparison of two different kinds of BLDC-Motors for application in handheld power tool drives. Whereas radial flux machines are well known and broadly used, the axial flux concept is less popular. One reason may be the more complex design process and the need to use 3D-FEM calculation. This paper describes the design process for both concepts and emphasizes the differences. For time efficiency, both analytical and FEM -based calculations are used in the design process. It will be shown that the axial flux concept is a realistic alternative to the well known motor. Due to the shorter axial length and the higher power density the drive can be optimized and the handling is improved.