Optimization Design of Outer-rotor Permanent Magnet Synchronous Motor

The direct driven permanent magnet synchronous motors are applied in many equipments, such as wind generator, machine tool, electric vehicle, fun and so on. Among different topologies, the outer-rotor permanent magnet synchronous motor (OPMSM) has the merit of high torque density. This paper investigates a kind topology structure of OPMSM, which adopts PM surface-mounted rotor and fractional-slot structure. First, the topology of motor structure is introduced. Second, the performance of initial design is investigated. Third, the OPMSM is optimized with global PSO algorithm in order to lower the cost. The skewed PMs are adopted to further decrease the torque ripple. Finally, the OPMSM with four-piece Halbach PM array is analysed. It shows the optimized OPMSM can meet the application requirements after adopting either skewed PMs or Halbach PM array.