基于定子电流的模型参考自适应感应电机转速估计

Stator-current-based MRAS estimator for induction motors

为改善无速度传感器感应电机矢量控制系统的低速性能,提出一种基于同步坐标系下定子电流的模型参考自适应感应电机转速估计方法。该方法以感应电机本身为参考模型,电机定子模型与转子磁链电流模型组合作为可调模型进行电机转速估计。将电流模型由静止坐标系变换到同步旋转坐标系以解决在低速情况下系统的交流信号受噪声影响严重,信号测量、滤波、计算和控制困难的问题。在定子模型中增加一个增益为实常数的补偿环节以克服转子电阻变化对磁链观测的影响。仿真分析结果表明同步坐标系下的模型参考自适应方法在低速估计性能方面更具优势,可获得较好的低速估计精度,具有良好的动态和稳态性能,且对电机参数变化具有较强的鲁棒性。

To improve the low-speed performance of a speed-sensorless induction-motor drive system, a stator-current-based model reference adaptive system （MRAS）type speed estimator in the synchronous reference frame was developed. In the estimator, the motor itself was selected as a reference model, and the stator model together with the current model of the rotor flux as an adjustable model. The curren- t model in the synchronous reference frame was used to solve the problems of filtering, sampling and controlling the AC variables in the stationary reference frame caused by the noise at the low speed. Fur- thermore, an error compensator with a real-number gain was added in the stator model to eliminate the error of the flux observation, and the error changed with the disturbance of the rotor resistance parame- ter. The simulation results show that the MRAS speed estimator in the synchronous reference frame is accurate. The system has a good dynamic and steady state performance in the low speed range, and also improves the robustness to the changes of motor parameters.