基于二阶滑模观测器的感应电机转子磁链观测

Second-order sliding mode observer for rotor flux of induction machine

实现矢量控制的基础是准确获得转速和转子磁链信息,本文提出了一种基于二阶滑模观测器的转子磁链观测方法。将构造的滑模观测器作为模型参考自适应系统(MRAS)的参考模型,将磁链的电流模型改造为该中间变量的可调模型,且其可调量为转速变量,进而构造出MRAS,实现对转速的观测。在此基础上,完成转子磁链的计算,并得到转子磁链角度,实现基于直接磁场定向的感应电机矢量控制。中间量的构造有效避免了传统MRAS中的纯积分问题,便于算法的实施;二阶滑模观测器有效地削弱了一阶滑模观测器存在的抖振扰动,并且参数具有较强的鲁棒性。仿真结果表明该转子磁链观测器具有较高的观测精度,且对外部扰动和转子电阻变化具有较强的鲁棒性,提高了系统的动稳态性能。

The basis of vector control is to obtain the speed and rotor flux information accurately. In this paper, a new method based on a second-order sliding mode （SSM） observer for rotor flux is presented. The observer is constructed by combining a SSM observer with a design on model reference adaptive system （MRAS） , and the SSM observer designed with the Super-Twisting algorithm is used as the reference model for the defined variable, while the adaptive model on the rotor speed comes from the current model of the flux. By means of the MRAS design, the rotor speed is observed. On the basis of this, the rotor flux and angle is calculated, and then the vector control of induction motor based on direct field-oriented is implemented. Since the MRAS is constructed directly on the defined variable, the pure integrator for flux calculation is avoided thoroughly, benefiting implementation of the observer. Meanwhile, the SSM observer can not only reduce the chattering disturbance in the first-order SM observer to a great extent, but also enhance the robustness to parameter. Simulative results show that the observer of rotor flux not only has high accuracy, but also is robust to the load disturbance and rotor parameters perturbation, and the stability and accuracy of the system is improved.