三相四桥臂逆变器输出电压负序分量抑制研究

与其它拓扑类型的三相四线逆变器相比,三相四桥臂逆变器具有电路形式简单,体积小,电压利用率高等突出优点,并通过增加第四桥臂,使其具有带不平衡负载的能力.然而由不平衡负载引起的三相不平衡电流会导致输出电压中含有负序分量和零序分量,对此可以采用两组PI控制器来实现输出电压控制.一组基于逆时针旋转坐标系的PI控制器用于调节正序电压分量,另一组基于顺时针旋转坐标系的PI控制器用于消除负序电压分量的影响.在此,提出并分析了一种基于两组旋转坐标系的三相四桥臂逆变器双闭环PI控制器设计方案,在此基础上设计了一台5kVA样机,并通过了实验验证.

Suppressing of the Negative Sequence Output Voltages for the Three Phase Four Legs Inverter

Comparing with various topologies of three phase four wire inverters, the three phase four legs inverter has many distinct merits such as simpler topology,smaller size and higher DC link voltage utilization.With the additional forth leg,three phase four legs inverter expands the control capabilities for unbalanced loads.However,the unbalanced three phase current caused by unbalanced loads leads to the negative order and zero order components in the output voltages.In this paper,two groups of P1 regulators are employed.One group of PI regulators are under the counter clock wise d,q,0 frame to control the positive sequence component of output voltage, and another group are under close wise d,q, 0 frame to eliminate the steady error caused by negative sequence component.A double loop PI regulator control scheme based on two rotating frames is presented.Analysis and design principles are verified by experimental results on a 5kVA proto-type.