Magnet skew in cogging torque minimization of axial gap permanent magnet motors

Several cogging torque minimization techniques exist for permanent magnet (PM) machines, and these are well documented in earlier studies. However, the majority are used to reduce the cogging torque in radial flux PM (RFPM) machines. In this paper, cogging torque minimization techniques for axial-flux PM (AFPM) disk machines are briefly reviewed, and one of the foremost cogging torque minimization method, magnet skew, is examined in detail. Various magnet skewing methods, types, and effects on the machine performance are also investigated. The results are compared with a reference AFPM machine, and the improvements are demonstrated.