【作者】 刘小虎；

【导师】 康勇；

【作者基本信息】 华中科技大学 ， 电力电子与电力传动， 2009， 硕士

【摘要】 近年来,双馈电机调速系统因其低成本和高可靠性等特点已经广泛应用于交流调速领域。本文的.研究针对变频器采用Back-to-Back变换器的双馈电机矢量调速系统,矢量控制系统采用基于定子磁链矢量定向的双环控制。在本文所研究双馈电机矢量控制调速领域,目前的文献绝大部分采用了速度外环与无功外环控制模式。通过建模分析知道,控制系统目标除了选择速度外环与无功外环控制模式,还可以选择速度外环与定子磁链外环控制模式,并且在常规的交流调速系统中,磁链控制是十分重要的。但目前的文献并没有分析比较两种控制模式各自的优缺点。本文针对这一问题展开研究。通过理论分析,本文认为电机在两种控制模式都可以稳定运行于各种工况。在不考虑电网电压变化的情况下,本文认为不论采用何种控制模式,电机定子磁链稳态值只取决于转矩电流大小。因此,定子磁链的稳态工作点是随转矩电流的变换而变换。对于采用PI控制的定子磁链外环,如果磁链指令值与实际稳态工作点不一致,将导致励磁电流进入限幅状态。此外,本文认为无功外环控制模式可以实现双环解耦控制,而定子磁链外环控制模式因为磁链稳态工作点的变动不能实现解耦控制。针对采用定子磁链外环控制模式的缺陷,本文提出外环采用P控制模式。这样可以避免因为指令值和工作点的不匹配导致励磁电流进入限幅状态。本文在Matlab/Simulink下搭建了双馈电机调速系统仿真模型,通过在各种工况下两种控制模式的仿真结果对比验证了本文的理论分析。本文的实验工作是在功率为4kW的双馈调速系统上完成的,实验结果验证了定子磁链外环采用P控制策略的有效性。更多还原

【Abstract】 Recently, the Doubly-Fed Induction Machine (DFIM) is becoming more and more popular in the motor drives because of the low cost and high reliability. This paper focuses on the research of DFIM which employs the Back-to-Back converter and the control strategy is the dual loop vector control based on the stator flux vector.The published literatures always use the dual loop control which contains the speed loop and the reactive power loop so far. The goal of control system can be not only the mode of speed loop and reactive power loop, but also the mode of speed loop and stator flux loop according to the modeling analysis. And generally speaking, the flux control is very important is the motor drives. However, few literatures have analyzed the pro and con of these two control mode. This paper tries to resolve the confusion of those two control strategies.By the theory analysis, this paper suggests that the DFIM system is stable under all working situation by using those two control strategies. The value of steady stator flux only depends on the torque current values in case of the stable grid voltage. Hence, the steady point of stator flux varies with the torque current. The flux current will be forced to be the limited state if the stator flux loop controller is PI controller and the reference vale of flux does not match the real flux value. Besides, this paper suggests that the mode of reactive power control can decouple the dual loop control but the mode of flux control can not do it because of the variation of flux steady value.This paper proposed that the flux outer loop employs the P controller in order to resolve the problem caused by the mismatch of reference value and real value of stator flux. The simulation mode is conducted in the Matlab/Simulink and the simulation results in many different situations verify the analysis proposed by this paper. The experimental setup is 4kW and the results show the validity of the flux control strategy which the outer loop controller is the P controller.更多还原