基于滑模观测器定子磁链观测研究

Research of Stator Flux Estimation Based on Sliding Mode Observer

定子磁链观测是直接转矩控制系统中的关键环节。基于电压模型的磁链观测方法是常用的观测方法,但其低速观测精度受定子电阻变化的影响,低速时,定子电阻压降在反电动势中所占比例较大,较小的定子电阻误差都会导致观测精度下降。提出了一种基于滑模观测器观测定子磁链的方法,通过滑模函数驱动估计电流跟随实际电流,实现对定子磁链的观测。该方法不含有定子电阻,对定子电阻具有完全鲁棒性,而且不需要定子电压信息。仿真结果表明该方法能在全速范围内准确观测定子磁链,且具有结构简单,容易实现的特点。

Stator flux estimation is the key element of direct torque control. The voltage model flux observer is the conventional method, but the accuracy is affected by stator resistance variation, at low speed, the statot resistance voltage drop is large in back EMF relatively, a little error of stator resistance can lead to precision degradation. A flux observer based on sliding mode observer was proposed, which drive the estimate statot current to actual stator current using sliding mode function to estimate the stator flux. The scheme doesn＇t involve stator resistance,it is robust to stator resistance completely, and does not require stator voltage information. The simulate results show that the scheme proposed can estimate stator flux accurately at overall speed, and has the advantages of simple structure, implement easily.