The Research On DTC System Of Asychronous Motor Based On Flux Linkage & Rotate Speed Idenfication

With the high speed development of power electronics and computer technology, AC electricity transmission systems are replacing DC ones step by step. The typical technology for AC motor control has VVVF, VSVF, VC and DTC etc. Direct Torque Control (DTC) of asynchronous motors, which has been developed in the recent decades, is a power control method for motor drives. Following the vector control technique , 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 t his paper, DTC of asynchronous motor was introduced based on analyzing AC motor mathematic model, and discussed the methods to observation of flux linkage, proposed measures to improve the u-i integral model. Analyzing the limitation of method to observe the stator flux linkage of traditional DTC, indicated the key approach to achieve improvement for DTC preferment is to observe the flux linkage accurately. To achieve it the author established a new observation flux linkage based on MRAS (Model Reference Adaptive System ),which choose the stator current as comparing signal and can effectively estimate the flux linkage and rotate speed with simple configuration.The speed estimation with speed sensorless is an important trend of modern AC drive. This thesis has discussed several primary algorithm of speed estimation and emphasized on the algorithm of speed estimate based on MRAS. It worth researching duo to it has excellent robustness and little be effected by the parameter of motor. The author improved the traditional model and bring forward a new algorithm with fliter of speed estimate based on MRAS.To verity the theory is right and practical, this paper achieves the simulating test which including stator flux linkage MARS models and speed estimate based on MRAS DTC system, and analyses the result of the test.In the last part of the paper designed the hard & software for the DTC system which bases on the central DSP chip of TMS320LF2407, the results of the xperiment fartherly certified the measures applied in the paper is feasible and right.