Rereach On Improved DTC System Using Sensorless Technology

This paper approves the traditional DTC technology of induction motor. First, using sliding mode variable structure controller instead of switching table controller which traditional DTC use, to produce the desired voltage vectors which can have any size and direction. And use a PWM controller based on new method to produce controlling signal which inverter use. Due to the using of this technology, the torque ripple and current harmonic are reduced, and the performance of robustness is improved. Then, approve the traditional flux observer based on U-I model, using a new method which compensates the amplitude and phase of flux before low pass filter. This technique can increase the accuracy of the observer, and extend the speed range which the observer can work normally. So the performance of DTC is improved. At last, using adaptive observer to realize the speed sensorless of DTC. The observer is designed by lyapunov stability theory combined with LMI, instead of pole assignment. The using of this technique can improve the stability of DTC and the accuracy of speed estimation. All the techniques above are verified by simulation using Matlab/Simulink. The results prove that the techniques this paper present are correct and feasible.