Research On Rotor Vector Control System Of Induction Motor Based On Three-Level Inverter

The thesis focuses on rotor vector control for induction motor with the diode-clamped three-level topology as the platform. The theory analysis of the neutral point potential problem, the induction motor operation model, simulation study of the control system, and experiment verification are done as the main parts of the research.Firstly, the topology of diode clamped three-level inverter and the theory of three-level SVPWM algorithm are introduced. A simplified three-level SVPWM algorithm on the coordinates of 60 degrees is explained; the result of the simulation in the Simulink verifies the validity of this algorithm. Secondly the vectors’ effect on the neutral point potential is explained. As to neutral point potential problem, many reseaches have been carried out and a solution to the problem called neutral point charge balance method has been demonstrated to solve it in the thesis. The simulation results of the system with the neutral point potential control strategy illustrate the problem is solved perfectly, all these verify the effectiveness of the method. After that, the model of induction motor on the three-phase stationary reference frame is introduced. The model of induction motor based on rotor flux orientation is derived and then the thesis introduces the theory of flux orientation. Based on numerous simulations, the result of induction motor based on rotor flux orientation model shows the fast dynamic response and good load capacity of the control system.in Matlab/Simulink simulation software.At last, it introduces the hardware circuit design of the three-level inverter control system based on TMS320F28335 and implements the improved three-level SVPWM algorithm based on the three-level inverter experimental platform; and the result of the experiment proves the improved three-level SVPWM algorithm is correct. Based on these, the experiment of neutral-point voltage balancing method proves the neutral point potential problem is solved perfectly, all these verify the effectiveness of the method. Followed by some research on vector control system of three-level inverter and the result of the experiments proves that the control system achieves the purpose of decouple control on the flux and torque of the induction motor, and has a quick dynamic response with Mid-Voltage & High-Power Inverter. At the end of the thesis, suggestion and prospect are proposed for the future work.