Research Of Induction Motor Flux Orientation Control System Based On Full-order Flux Observer

The research focuses on the method of full-order flux observer for speed sensorless drive and rotor time constant identification of induction motor, based on flux orientation and the platform of diode-clamped three-level topology. And the research of induction motor flux orientation control was done by the theory analysis of the induction motor operation model, simulation of the control system, and experiment verification.Firstly, the topology of diode clamped three-level inverter and the theory of three-level SVPWM algorithm are introduced, and the diode-clamped three-level inverter switching state and switching vector are analyzed. The decision of the sectors and reference voltage vector and calculation the switching vector duration by selecting the switching vectors are given based on realization of the digital control system. Then, the model of induction motor on the three-phase stationary reference frame, synchronous reference frame and the model of induction motor based on indirect rotor flux orientation are introduced. Followed by the analysis of induction motor mathematical model, full-order observer is set up. The speed and rotor time constant adaptive laws are given along with the assumptions and derivations according to Lyapunov stability theorem. After that, the root loci of the observer at rising speed, stability of the discretized observer model and the root loci of introduced feedback matrix observer are analyzed, and then the observer is configured. Later, the introduction of speed sensorless control system and parameter identification system simulations based on full-order flux observer is given, in Matlab/Simulink simulation software. Based on numerous simulations, the result of speed sensorless vector control simulation system model shows speed estimation has a good tracking performance and a good robustness to the load variation, and the result of motor parameter identification simulation system shows that the rotor time constant can be accurately estimated in some certain conditions.Finally, the experiments of speed sensorless control are carried out on the platform which consists of TMS320F28335 and EPM570 as the control unit, the diode clamped three-level power unit and motor unit, based on full-order flux observer for speed sensorless control system. The results verify the correctness of the corresponding algorithm, and the experimental results are analyzed and summarized. Suggestion and prospect are proposed for the future work.