三、定子电流与转子电流的关系 异步电动机转动后，转子电路的等效电阻(1-s)R2/s 增加， I2减小。当s =1，(1-s)R2/s = 0 ，异步电动机起动，转子电路相当于处于短路状态，此时电流很大；随着n 的增加，I2不断减小，当s =sn=0.01～0.09 时，转子电阻相当大，I2减小到额定值。 和变压器相似，异步电动机的转子电流产生的磁势也具有去磁性质。磁势的平衡方程式如书P. 31 式（3-2-11）和式（3-2-12）。 当机械负载增加，转速降低，电阻R2/s 减小， I2增大，去磁作用增强， I1也随之增大。

Abstract —— The doubly fed induction generator is particularly appropriate to be used in wind power generation systems. However, in weak grids its stator connection to unbalanced or distorted voltages imposes low frequency and high amplitude rotor current harmonics. Also, the grid side converter must deal with the same voltage conditions. The paper addresses the first issue presenting a voltage harmonics controller in the dq reference frame to be included in the high dynamics rotor current controller. Simulation and experimental results demonstrate the performance of the proposed controller imposing a sinusoidal input current.