Reduction of Cogging Torque by Notching Groove on Magnets in SMPMSM

Surface mount permanent magnet synchronous motor (SMPMSM) is widely used in industrial fields. In order to improve its working accuracy, the cogging torque needs to be reduced. This paper studies the effect of notching groove on magnets on cogging torque in SMPMSM. The general formula of cogging torque under arbitrary groove on permanent magnets is derived by the energy method. Based on the equivalent structure of rectangular grooves and Fourier expansion, the formulae of the torque under single rectangular groove and double rectangular groove are derived. To get an optimal solution, the cogging torque of SMPMSM under notching single and double groove with different sizes is analyzed by using Finite Element Method. The research shows that the cogging torque of SMPMSM can be effectively reduced by notching auxiliary groove on permanent magnet.