Control scheme for three-phase pulse-width-modulation rectifier under unbalanced grid conditions
不平衡电网中三相脉冲调宽整流器的控制

By the mathematical model of the pulse-width-modulation(PWM) rectifier and the characteristics of the unbalanced grid, we propose a new dual close-loop controller for the three-phase rectifier to reduce the second-harmonic power content on the DC side when the grid voltages are unbalanced. A fuzzy PI control is used in the voltage outer-loop to improve the speed of the dynamic response. Separate controls for the positive and negative sequence currents are employed in the current inter-loop with no decomposition of the current. The simulation results show that the proposed controller adjusts the DC voltage rapidly, reduces the harmonic power content and improves the dynamic performance of rectification under the unbalanced grid voltage condition.