The Research Of Stator Resistance Observation Of DTC In The Induction Motor

Direct Torque Control (DTC) of asynchronous motors which has been developed after the vector control technique, is a power control method for motor drives, the quick development of DTC makes itself a new high-powered Alternating Current(AC) driving technique paralleling to the vector control. The DTC system has many advantages such as simple realization and excellent dynamic response and perfect robustness etc.In Perfect rator Field Oriented Control (FOC) methods, the controller is dependent on both the rator and rator parameters. Compared with FOC, DTC minimizes the use of machine parameters, but one of the limitations of DTC is the use of stator resistance for estimation of the stator flux. The variation of stator resistance due to changes in temperature and frequency makes the controller operation difficult at low speeds. Improving the performance at low speeds if the stator resistance is measured or estimated during the operation of the machine.Combining intelligent control and DTC operating principle, the methods of stator resistance estimator in DTC are discussed synthetically, and comparing some estimating methods of stator resistance estimator. Then a stator resistance estimator witch using Fuzzy Logic is proposed. The estimator overcomes the difficulty of calculating complex mathematical axiom, it has advantages such as simpleness, economize time, response quickly on calculating stator resistance.On the theoretical analysis of stator resistance estimator, Direct Torque Control system simulating model is build based on MATLAB/SIMULINK, and analyze the conclusion .In the end, the paper designed a DTC system using the TMS320F2407A which is specialized controlling machine. The experiment witch implementing on 75KW induction motor proves validity of the theory derivation and simulink models.