Research On Low-speed Control Of Asynchronous Motor Based On DSP

Speed sensorless vector control of induction motor system has always been the hot spotof the international scholars research topic, while the speed identification and control of thesystem, especially in the low speed, has been the focus of the study.Based on the theory of vector control of induction motor, the equivalent dc motor modelof ac motor based on coordinate transformation is introduced, then according to the currentmodel, we calculated the flux angle of the rotor flux oriented vector control system, whichimplements the stator current excitation and torque component of decoupling. To solve theproblem of speed identification, we introduced the basic principle of Model ReferenceAdaptive System firstly. Then a speed identification algorithm called the MRAS model withdynamic Kp and Ki based on the BEMF is presented. For the control of induction motor atlow speed, to solve the problem of the inaccurate speed identification under low speed andload capacity is not strong, a low speed Iq control method is proposed.The current model, MRAS model and low speed Iq control model is simulated on Matlab.The results show that the current model can accurately identify flux angle, the MRAS modelcan accurately identify the rotor speed in the high frequency, and the low speed Iq controlmodel can make motor rotating in1Hz exactly with strong loading capability. Through theobservation of the Labview software, we use a2.2kw asynchronous motor for test whichverify the feasibility of the above three models.Finally, the paper gives the software architecture of the vector control frequencyconverter based on TMS320F28035and detailed introduces the vector control program flowchart.We give the physical platform and physical picture of project practice at the end of thearticle.