Speed-Sensorless Vector Control Of Induction Motor Based On DSP

The speed-sensorless vector control of induction motor is one of the hot topics in electric-drive field, whose main study is to adopt a kind of quick and effective method to accurately observe the rotor flux and rotor speed in the condition that the parameters vary and certain and uncertain disturbance exists. In order to obtain this aim, this paper study the speed-sensorless vector control of induction motor from two directions, one is the conventional method for observing rotor flux and speed, one is observing rotor flux and speed based on the extended Kalman filter.As studying the conventional methods for observing rotor flux and speed, the flux observation and its improved method based on voltage and current model is analyzed and its deficiency is also presented. Then the observing methods for flux frequency based on reference model are introduced and the d-axis voltage model is adopted to observe the rotor flux frequency. This method is applicable for the vector control of induction motor without considering the magnitude of flux. While observing the rotor speed, the error of torque current is utilized. The PI-adjustor algorithm adopted by this method is simple and can be easily implemented. At last, these two methods are synthesized to construct a simplified system for speed-sensorless vector control of induction motor, which is affected little by the parameters of motor. The results of simulation verify this method.As studying the extended Kalman filter, the rotor speed is selected as an extended state firstly and the linearization of a discrete state formulation is deduced. The results of simulation prove the efficiency of this method. Considering the large variation of rotor resistance in real operation, it is observed by being selected as an extended state being similar as the rotor speed. The results of simulation show that this method can observe rotor flux better than the extended Kalman filter with only speed observation in the same condition. Under the illumination of the thought, I deduce an extended Kalman filter with multi-states.Then the designation of hardware platform for motor control is described in details with main circuits and control circuits. The main contents are composed of the characteristic of intelligent power module and the chip TMS320DSP and itsevaluating board, the selection of power source, the connecting and protecting circuits for inputs and outputs. The detailed schemes of circuits are also presented. The vector control of induction motor with speed sensor is implemented through programming using DSP on this experimental platform. The results of experiments show that this system can obtain good control effect under low and high speed.