The Chaotic Detection Mechanism And Method Of Vector Controlled Induction Motor At Very Low Speed

Presently, the induction motor's speed sensorless vector control technology mainly make use of the stator current and voltage, which are easily detected, to access to the rotor speed indirectly. It usually gets satisfactory control performance. However, the stator current and voltage is relatively small at very low speed, with large error of the measured voltage and current signals. As a result, the system's control performance deteriorate, and hardly to achieve. Therefore, this paper used chaos detection system to replace Hall sensor in order to detect the stator current and voltage signals accurately, by taking advantage of the chaotic sensitivity to initial conditions and noise immunity, and conducted in-depth research. It provides a new idea for the applications of speed sensorless technology at very low speed.Firstly, the chaotic state of weak signal detection method was proposed, based on the inverted sawtooth map model and symbolic dynamics description methods. According to the different types of power supply, there are chaotic state weak signal detection circuit of constant-current and chaotic state weak signal detection circuit of constant-voltage. Then, a numerical simulation model was established to validate its effectiveness.Secondly, the chaotic- periodic states of weak signal detection method was introduced. We took Duffing equation as the model, and putfoward a method to detect frequency micro-variation of sine signal. In addition, studied the initial phase of the weak signal detection method, proposed a simple dichotomy effective indentation phase detection method and two extraction methods of weak signal amplitude.Then, the induction motor vector control theory and its mathematical models were analyzed, with the speed estimator model. Using Matlab/Simulink software, the simulation model of vector control induction motor and simulation model of very low speed chaos detection were constructed, and designed chaos detection system and speed estimator, accurately detected the very low rotor speed.Finally, the research work in this paper was summarized, and looked forward to the next study.