A Dual Notched Design of Radial-Flux Permanent Magnet Motors with Low Cogging Torque and Rare Earth Material

This paper proposes a dual notched design of radial-flux permanent magnet (PM) motors with gear-shaped structures on the PM and stator teeth aiming at lowering down cogging torque and rear earth material (REM). Due to the restriction on export quotas of REM, its cost is expected to rise drastically in the near future. The low cogging torque and REM in PM motor design, therefore, are of high significance. This paper presents a design taking a big step toward that direction. Four models with different mechanical angles and depths were designed. With the aid of 3-D finite element analysis and simulation, the one that best matched objectives was selected which resulted in percentage reduction of the cogging torque and REM up to 62.8% and 6.7%, respectively. In the transient simulation, the output torque of a dual notched PM motor compared with a normal structured one was reduced to 6.5% in average. A prototype was also fabricated to validate the design.