基于虚拟电网磁链定向控制的PWM整流器控制策略研究

Control Strategy for PWM Rectifier based on Virtual Line-Flux-Linkage Oriented

电压型PWM整流器跟三相交流电机定子电路有很大的相似性,采用类似于交流电机磁链观测的方法构造出虚拟电网电压矢量作为PWM整流器矢量控制的发生矢量,可以达到降低PWM整流器成本的目的。准确观测虚拟电网磁链成为该控制策略的关键,本文采用改进型的虚拟磁链初值计算方案,能够比较准确的对虚拟磁链初值进行估计,解决了整流器启动过程中冲击电流过大甚至无法启动的问题。仿真和实验结果跟试验验证了观测方法的正确性。

There is a great similarity between the circuit of three-phase voltage-source PWM rectifier and the stator of an inverter-fed AC motor. Therefore a virtual line-flux-linkage vector can be constructed similarly to the observation of AC motor flux linkage, which may serve as the oriented vector in the vector control of the PWM rectifier instead of the line voltage vector. As a result, the line voltage sensors will be eliminated and the costs of PWM rectifier can be reduced. The key problem of the virtual line-flux-linkage vector oriented control of the PWM rectifier without line voltage sensors is to observe the virtual line-flux-linkage accurately. A new modified method to observe the virtual line-flux-linkage is been put forword this paper, which will restrain a large current rush, which sometimes could even cause the rectifier hard to start up. The validity of the observer has been proved good through the result both simulation and experiment.