基于MRAS的异步电机无速度传感器直接转矩控制

【作者】 沈红平；

【导师】 喻寿益；

【作者基本信息】 中南大学 ， 控制理论与控制工程， 2007， 硕士

【摘要】 论文基于模型参考自适应系统(MRAS)原理设计了一种新型的自适应速度磁链观测器，把磁链观测和速度辨识结合在一起，将定子磁链观测值直接应用于直接转矩控制算法。论文着重阐述了设计中的两个重点部分，增益矩阵的求取和自适应律的推导。对增益矩阵的求取本文采用一种简便、实用的方法，利用MATLAB进行磁链观测器极点的配置，得到目标增益矩阵。参数的辨识基于电机状态空间方程，以定子电流和定子磁链为状态变量，电机本身作为参考模型，构造全阶状态观测器为可调模型，转速观测值为可调模型的可调参数。由于状态方程以定子电流和定子磁链为状态变量，定子磁链可直接观测得到。定义李亚普诺夫函数，根据其稳定性要求确定转速自适应律，实现了异步电机无速度传感器直接转矩控制系统。证明了稳定性条件，保证了系统的稳定性和观测器的观测误差在全速范围内逐渐趋于零。虽然观测器对定子电阻变化有良好的鲁棒性，但在极低速时电机定子电阻压降引起的转速观测误差仍然不可忽略，观测器同时辨识定子电阻，确保了系统在低速时对定子电阻的变化仍有良好的特性。利用SIMULINK中的库元件和S-function构建了异步电机无速度传感器直接转矩控制系统仿真模型。仿真结果表明提出的速度磁链自适应观测器对速度辨识快速准确，算法简单，计算量小，便于在线实现。观测器对定子磁链观测精度高，低速时也有较好的观测精度，能改善电机的低速控制特性。转矩动态响应快，可以很好的克服纯积分器误差积累和零点漂移的缺点。最后讨论以TMS320F2812为核心构成控制器，实现异步电机无速度传感器直接转矩控制系统数字化的方案。更多还原

【Abstract】 This paper designs a new speed-adaptive flux observer which based on model reference adaptive control system theory. The observation of stator flux and estimate of speed were proceeding at the meantime, the observed stator flux could be applied to direct torque control system. The paper emphasize expound two keystone parts in design, which are stationing the pole of flux observer and selecting plus matrix. With regard to station the pole of flux, the author adopt a sort of simple and convenient means, which is in virtue of MATLAB, and finally find aim gain matrix. the reference observer is based on motor state space equation, which used stator current and stator flux as state variable, motor itself as reference model, the designed observer as modulation model, speed observer as modulation parameter. Because the state equation’s state variables are stator current and stator flux, the stator flux can be observer direct. After defining Lyapunov’s stability theory the speed self-adaptive scheme is confined. And then the speed sensor less direct torque control emulation system was designed. The proving of stability theory condition ensures the system is steady. The voltage fall of stator resistance can also affect the precision of speed observer when in very low speed although the observer has perfect robust trait, so the stator resistance is observer at the same time. Which make sure the system has perfect characteristic to stator resistance change even in the very low gear.Based on the element and S-function in SIMULINK, the simulation former of speed sensor less direct torque control system was set up. The emulate experiment results indicate that this system is perfect , such as the speed estimate is quick and nicety, The arithmetic is simple, all this is easy to implement on line. And also the system has preferably observe precision of stator flux even in the low gear, so the control character of motor can be improved. The torque dynamic respond is quick, so the limitations of error accumulate and zero point excursion which is on simple integrator can be conquer. At last, it discusses a scheme, which is the speed sensor less direct torque control system of asynchronous motor is digitized realization based on the controller’s core is TMS320F2812.更多还原