Operating Characteristics in Low Speed Range of Vector Control of Induction Motor withoutSpeecl Sensor Using Speed and Flux Observers

在传统的MRAS方法中，速度估计值是PI控制器的输出，PI控制器接收来自速度自适应控制器的输入信号。由于速度估计值中含有时滞，系统响应变差，在低速范围内会出现不稳定现象。在该方法中，速度和磁链观测器由电流模型磁链观测器和电压模型磁链观测器组成。新的速度估计值理论上不包括时间延迟。在实际应用中，由于电压检测误差的存在，会引起转子转速的不稳定。最后，仿真结果表明，系统响应良好，在低速范围内不会出现不稳定现象。

In the conventional MRAS method, the value of velocity estimation is the output of the PI controller that received its input signal from speed adaptive controller. As the value of velocity estimation includes time delay, the system responses are worse and the instability occurs in the low speed range.In the proposed method, the speed and flux observers are composed of the current model flux observer and voltage model flux observer. The value of new velocity estimation does not include time delay theoretically. So, the system responses are improved.In practice, the instability of rotor speed are caused by voltage detection error. The feedback of the out of current model flux observer to the input of voltage model flux observer is effective for stabilization in this case.Lastly, the simulated results show that the system responses are good and the instability does not occur in the low speed range.