Based On Three-level Inverter Speed Sensorless Control System

With the proposing of the vector control, the induction motor of more variable, strong coupling problems have been solved. The speed sensor vector control can’t meet the need of industrial control, but in some occasions, it doesn’t fit. So we must adopt a non-speed sensorless vector control system. Speed sensorless vector control system has high practical value and theoretical significance. In this thesis, sensorless vector control system has been studied extensively.With rapid development of the power electronics technology and the increasing of the power level, the traditional two-level technology can not meet the needs of real control, but the introduction of three-level technology can cover the shortage. In this thesis, high-power sensorless vector control system is studied. First of all, three-level technology were described and given a detailed analysis of its principle and the derivation of three-level SVPWM. Secondly, motor control technology for the indirect field oriented control is analyzed and deduced to establish a high precision control of vector control methods. Finally, this thesis presents the method of sensorless and conducts a discussion and a research of the dynamic model reference adaptive speed estimation method. With the combination of advantages and disadvantages of the voltage model and current model, a voltage compensation term with the flux estimated model is proposed to improve the flux estimation performance and robustness. It also theoretically analyzes the model reference adaptive and gives a detailed presentation of the flux model reference adaptive method, and for the voltage model which is made of pure integral part, it proposes back-EMF. Finally, for the EMF with stator resistance, a fully robust method with reactive power is presented. In this thesis, Matlab/Simulink is applied to establish a speed sensor vector control system based on three-level, and establish several methods of the sensorless vector control based on three-level and analysis and research for it in the way of low-speed performance and parameters of robustness are also given. This paper focuses on the feasibility of the practical application of several speed sensorless scheme and it compares the advantages and disadvantages of these methods, getting some more reliable data and conclusions.