The Vector Control Of Speed-adjusting Of Asynchronous Squirrel-cage Induction Motor

Today,there is a lack of sufficient energy resources, energy conservation has very important significance. In our country,Much energy is being consumed by the motors. The traditional speed-adjusting methods cause energy waste because of narrow speed range and low energy efficiency, so high-effect speed-adjusting methods are in urgent need.In the past,the control law is based on the steady-state model,so the dynamical performance is not satisfactory. The vector control which is based on dynamic model is the advanced control method for its high dynamical performance.This paper researches on the asynchronous squirrel-cage induction motor,and the vector control system of speed-adjusting is established. Firstly, the mathematics model of asynchronous motor is developed, the stator current is decoupled into the flux and torque-producing stator current according to the coordinate transformation and the rotor-flux orientation. Secondly,the circuit construction of the speed-adjusting system is introduced, the principle of the inverter is also analyzed in detailed. The realization of flux-orientation is very important in the speed- adjusting system. In this paper,the method of how to obtain the flux is introduced, the flux monitor in rotor-flux-oriented reference frame is also analyzed .The flux monitor is presented and simulated,which sets a good foundation for further studying.At last, the dynamic characteristics and stable performance of the vector control system are simulated in MATLAB/SIMULINK,the system shows high dynamic response characteristics .