A Method On Estimation Of Speed Of Induction Motors Using Stator Voltage

Sensorless vector control system of induction motor is not only an important aspect but also a hotspot of investigation in modern AC drive. The key problem is that how we can get the speed of motor accurately. Speed sensorless motion control system has under gone a rapid development in the past decade. This paper presents the state of art of speed estimation strategies on speed sensorless control, and the advantages and disadvantages of the each method are discussed. Some future trends in the reaserch field are high lighted. The method of Speed estimation based the current or voltage of stator is mainly concerned with the extraction of the speed information contained in the rotor slot-ripple harmonics created in the airgap of the induction motor using digital signal-processing. The method has many advantages, for example, the resolution of speed estimation is not influenced by the changes of motor'parameters, it can be fit to all kinds of loads and it can get satisfied results in a great speed range.The paper not only described maths model of perfect inductor and the harmonic composition of unperfect inductor, but also analysed the method on Estimation of Speed of Induction Motors Using Stator voltage from the aspect of slot-ripple harmonics in inductor. Based on the theory, paper built up a model of inductor and a arithmetic to estimate the speed of motor by using MATLAB/SIMULINK called forth computer language. The paper used the emluator to simulate the system of inductor and compared the results of simulation and experimental results. Furthermore, in order to validate the method of speed estimation is valid, the paper designed system of data processing to extractive one-phase stator voltages respectively form inductor Y132M1-6 produced by chongqing motor inductor and special inductor QABP90L2A produced by ABB company in different loads and different frequencies of PWM transducer and used the data of voltage to estimate speed of inductor and analyzed the experimental results of estimation in detail.A novel approach in sensorless speed detection for adjustable-speed AC drive is described in this paper. No a priori knowledge is required about the motor construction, electrical parameters, or load condition by using this method. In addition, no external tuning is needed for the system. The new technique is based on instantaneous spectral estimation using the fast Fourier transform whereby the speed-dependent slot-ripple harmonic frequency is determined. By using MATLAB/SIMULINK, this paper is...