The Analysis Of MW Level Direct-drive Permanent Magnet Wind Generator's Harmonic And Its Effect On The Generator

Wind power is clean and renewable, it has the advantage of no fuel, no occupation of cultivated land, non-polluting. And wind power generation has low operating cost. The world's wind power industry has developed rapidly, MW wind turbines have been more common.Although China's wind power industry started late, but in recent years the annual increase of wind turbine capacity is leading the world. Development of wind power generation technology is an important way to solve the energy problem in china.The wind turbine directly drive wind generator for Permanent magnet wind power system. Although the gearbox would not to be needed anymore, but the wind turbine causes more vibration for wind generator.Wind generator's rated speed is too low because of the direct-drive operation , then the motor has to be too large. Self-generated torque ripple could make an manifest effect low-speed motor,when it coupled with the vibration of wind turbine, a greater hazard will make to the wind generator.Therefore, we should minimize the air gap harmonic magnetic field and the time harmonics to reduce the torque ripple. For the NdFeB permanent magnet, eddy loss should be analyzed in order to avoid excessive temperature rise and the loss of magnetic's field.This paper analyzes the permanent magnet wind generator's magnetic field harmonics for no-load, and discuss the ways of weakening space harmonics; If the calculation of the finite element model and the calculation of outside circuit were combined, more accurate and efficient analysis of time harmonic could be get when the permanent magnet wind generator take a load by way of non-controlled rectifier.Finally the motor excitation force and eddy current loss analysis have been made.