Research And Realization Of Vector Control Strategy For Induction Motor

With the development of power electronics and microprocessor technology, the control performance of normal induction motor that based on the high performance vector control system can be approached to the asynchronous motor's and the capability of energy-saved is quite good. Moreover, due to the advantages of induction motor that includes high performance to cost and convenient to maintenance and more than half use in all drive power in actual system, so it is very necessary to improve and enhance the performance of variable frequency speed-adjusting system of the induction motor and reduce the complexity of the control system. Therefore, the purpose of this paper is focused on the theories and experiment research of the vector control system of induction motor, the main research contents and results are as follows:(1) The vector control system (VCS) of induction motor that based on voltage-source type inverter and TI2407DSP is researched in this paper. The mathematics model of VCS is established by Field Oriented Control (FOC) principle which is popular in motor control. The whole variable frequency speed-adjusting system structure includes rotor speed that has torque inner-loop and flux close-loop. The current to voltage decoupling process that uses voltage-source type inverter and the realization of flux weakening control is also studied in here. During flux weakening, the appointed value of magnetizing current is calculated by MATLAB. The well decoupling control scheme can obviously improve the response ability of the VCS of induction motor is proved by experiment results.(2) With the heavy computation, easy saturation and cumulate errors of conventional direct vector control's considered, the vector control of induction motor based on simple model is studied and the detailed scheme is described based on the rotor flux is decomposed and approximated. Through the direct close loop control of magnetizing current and torque current and the complex process that current to voltage is included by PI regulator, so the direct vector control of induction motor is simplified. The proposed method is effective by experimental results. It shows that the simplicity of the code program, rare saturation and shocks.(3) The whole digital VCS of induction motor are studied by experiment. In hardware design, the important parts are the drive circuit of IGBT, the over-current and over-voltage circuit, the phase current and rotor speed detecting circuit. In software design, it is completed by subroutine debugging. The effective of vector control of induction motor based on simple model which is this paper's main research content are proved by experiments, and the experimental results are also analyzed.