IEEE TRANSACTIONS ON MAGNETICS, VOL. 48, NO. 11, NOVEMBER 2012 

Sun-Kwon Lee , Gyu-Hong Kang , JinHur , and Byoung-Woo Kim 

This paper presents the stator and rotor shape designs in interior permanent magnet (IPM) type brushless dc (BLDC) motor for

reducing torque fluctuation. The partly enlarged air-gap made by rotor unequal out diameter and stator core structure with pole shoe

modification is introduced. The torque ripple reduction is achieved by upgrading torque value at minimum torque position and their

detail characteristics are compared. The final stator and rotor shape of IPM type BLDC motor is decided by design of experiments

(DOE) process. The magnetic field and torque characteristics are analyzed by 2 dimensional (2D) finite element analysis (FEA) and their

performances are validated by experimental results.