低速运行时异步驱动转速自适应观测器稳定性分析与设计

Analysis of the Stability of Speed Adaptive Observer and Its Design for Induction Motor Drive at Low Speeds

尽管全阶观测器广泛应用于异步电驱动系统进行速度观测,但其稳定性问题,尤其是低速再生模式下的稳定性问题一直没有得到很好的解决,制约着无速度传感器系统的低速运行性能。该文在建立转速自适应观测器传递函数的基础上,对其不稳定问题的成因进行了揭示,并对其不稳定区域进行了量化界定。为改进转速自适应观测器的低速性能,提出一种误差加权自适应律设计方案。该方案直接将励磁电流分量误差引入到转速自适应律中,并通过权重系数的合理设计获得了较好的低速运行特性。根轨迹分析表明了所提方案的低速稳定性,而且对比研究表明,该方案具有更好的阻尼特性和收敛过程。4kW异步电机仿真和实验验证了该文所提方案的有效性,同时也验证了理论分析的正确性。

Although full order flux observer is widely used in induction motor drive for speed estimation,the problem of stability,especially in low-speed regenerating mode still has not been solved very well,resulting in limited operation performance in low-speed range.Based on the equivalent transfer function built in this paper,the reason for unstable operation is exposed,and the corresponding unstable region is identified quantitatively.To improve the operation performance at low speeds,a novel speed adaption scheme,i.e.error weighting adaption,is proposed.In this scheme the magnetizing component of the stator current is introduced into the adaption process directly,and the performance can be ensured by proper design of the weighting coefficient.Through root locus analysis,the low-speed stability of the proposed error weighting adaption observer scheme is demonstrated,and through the comparison analysis,the better damping characteristics and converging process brought by this error weighting adaption observer are clarified.At last,the validation of the scheme and the correctness of the theory analysis are confirmed through simulation and experiments on 4 kW induction motor.