中文说明：
对电网不平衡情况下的三相PWM整流器进行了详细的建模分析，并在此基础上研究了两种不平衡控制策略。其一是抑制网侧负序电流的控制策略，主要控制三相PWM整流器交流电流对称正弦化控制。其二是抑制直流电压谐波分量的控制策略，主要控制三相PWM整流器从电网吸收平衡的瞬时功率，消除直流电压中的各次谐波分量。
English Description：
The three-phase PWM rectifier with unbalanced power grid is modeled and analyzed in detail, and two kinds of unbalanced control strategies are studied. One is the control strategy to suppress the negative sequence current of the grid side, which mainly controls the symmetrical sinusoidal control of the AC current of the three-phase PWM rectifier. The other is the control strategy to suppress the harmonic components of DC voltage, which mainly controls the three-phase PWM rectifier to absorb the balanced instantaneous power from the grid and eliminate the harmonic components of DC voltage