Research On Stability Of Induction Motor Speed Sensorless Vector Control System

Based on traditional voltage model, the stabilities of three-phase asynchronous motor’s speed sensorless vector control system with rotating start and low-speed regenerating mode are firstly introduced and studied, and flux collapse problem is described in this thesis. A novel voltage model based on compensated gain is proposed to curb flux collapse phenomena.The main contents of the thesis are as follows:1. The mathematical model of three-phase asynchronous motor in three-phase state coordinate system is studied and the principle of coordinate transformation is analyzed. The three-phase asynchronous motor’s mathematical models in two-phase static and rotary coordinates are deduced, and the models are simulated.2. Based on the analysis of stability for three-phase asynchronous motor’s speed sensorless vector control system with low-speed mode based on traditional voltage model, the parameter self-optimization voltage model is proposed, which can help the system self-optimize on the electrical rotor speed, and the stability of low-speed regenerating mode for three-phase asynchronous motor with the speed sensorless system is greatly improved. The results of the simulations and experiments demonstrate the effectiveness of the method.3. The multiple equilibrium states existed in three-phase asynchronous motor flux are explored, and the characteristics of the equilibrium points of three-phase asynchronous motor with rotating start based on voltage model are analyzed. An improved voltage model based on compensated gain is designed, and the results of the simulations and experiments show that the model realizes the steady operation of three-phase asynchronous motor with rotating start.