No abstract

P ermanent magnet direct drive motor has become the most promising solution for wind generation because of its advantages of high power density, high efficiency, high reliability and low maintenance cost. However, with the increase of the motor power grade, the excessive volume and weight of the motor are obstacles to its manufacture, assembly, transportation and installation [1]. The large permanent magnet direct drive wind generators are large in volume and mass. The main reason is that they not only include effective materials that produce electromagnetic torque, but also include structural materials that transmit torque. In order to overcome the torque load without plastic deformation or fracture, and ensure that the deformation at the air gap of the generator does not exceed the allowable value. The size and mass of structural are greatly increased for its Stiffness and strength requirements. Rotor supporting is one of the key factors to determine the weight of generator [2]. In the specific construction design stage of wind generator, when it comes to the design of every component, the designers often depend on their experiences, lack theoretical guidance, and often for safety reasons to choose some structural dimensions. Therefore, the design is conservative. This