Abstract: In recent years,with the extensive use of variable pitch systems,quality problems of key load-bearing components of draught fan have frequently arisen.Due to the large output torque of the AC pitch drive motor,that the blades,gears and bearings frequently withstand excessive instantaneous torque,which is prone to structural damage such as cracking,and eventually leads to the damage of draught fan.The traditional control strategy only simply satisfies the principle of power optimization without considering the influence of its control on the fatigue life of the fan bearing components under different working conditions and wind speed.In addition,it cannot reduce the fatigue stress and impulse of key components of the unit when pitching.In view of the above problems,this paper starts with exploring the general law of the torque variation of the fan servo pitch drive with the fluctuation of wind speed.The torque smoothing increase coefficient and the torque smoothing decrease coefficient are designed to control the output torque recovery of the pitch drive.On the basis,it is ensured that the impacts of blades,gears and bearings can be well mitigated when the wind with different strength is changed,and the proposed method is verified and modified by simulation experiments.

Key words: permanent magnet synchronous generator, flexible pitch control, servo drivers, wind power generation