Induction Motor Direct Torque Fuzzy Control Technology

With the rapid development of the power and electric system and computer technology, AC drivers are replacing the conventional DC drivers. The control method of AC motor (Induction Motor) is very excessive, Comparatively, DTC is much more advanced. In DTC, the mathematic model of AC induction motor is analyzed in the stator coordinate and the flux and torque are controlled directly. Therefore, much coordinate rotate transformation and complicated computation are saved and the control method is novel, simple and direct. Fuzzy control is robust, and it is a better way to realize direct toque control.In this thesis, the feedback current and voltage of the motor are made use to compute the torque and flux directly, and use fuzzy control method to select the state of the inverter. The DTC of motor is realized; the stator is trained off-line and detected on-line by FNNS (fuzzy neural network system), so in DTC low speed performance is effectively improved; at the same time PI is used to control the speed, the low speed exceedance and transition placidity are attained.From the result of the experiment, the observed error of the stator resistance is less than ?% , that can satisfy the industry control, and from the result of the simulation, the torque can reach the given demandiin 0.3μs, the flux trace is close to a circle. The fluctuation of current and flux is small. So, compared with the previous control method, the method in this paper has many advantages, such as quick torque response, high dynamic and static performance. Therefore, this method is promising.