三相四桥臂逆变器的改进分序控制策略

为了提高逆变器带不平衡负载的能力,提出一种适用于三相四桥臂逆变器的正负序解耦控制策略。该控制策略基于双旋转坐标系,实现正负序电压的解耦和分离,在正负序同步旋转坐标系下采用PI双闭环控制算法。针对零轴的独立控制,通过虚拟构造出Uα、Uβ分量,把零序分量逆时针转动90°构成αβ坐标系,再通过Park变换将αβ分量转换成dq直流量,从而对直流量进行反馈控制。由仿真结果可得,上述控制策略可以有效抑制不平衡负载电压的不平衡度。

Improved Sequential Control Strategy for Three-phase Four-leg Inverter

To improve the inverter’s capacity under unbalanced load,a positive-and negative-sequence decoupling con?trol strategy for a three-phase four-leg inverter is proposed.This control strategy is based on a double rotation coordinate system,and it can realize the decoupling and separation of positive-and negative-sequence voltages;in addition,the PI double closed loop control algorithm is applied in the positive-and negative-sequence synchronous rotating coordi?nate system.For the independent control of zero axis,the zero-sequence component is rotated counter-clockwise by 90°to form anαβcoordinate system by constructing components Uαand Uβ;afterwards,theαβcomponents are converted to the dq DC quantities through the Park transformation.In this way,the feedback control of DC quantities is realized.Simulation results show that the proposed control strategy can effectively suppress the imbalance degree of unbalanced load voltage.