Research On Vector Control System Of Full-order Observer Based On Three-Level Inverter

With the emergence of high performance control theory of AC electromotor, the appearance of high switching frequency and large-capacity switching devices, as well as the improvement of large scale integrated circuits, microprocessor, digital signal processor, etc. DC electromotor which has been widely used in the control system is replaced by AC electromotor; meanwhile, AC speed regulation is gradually substituted for DC speed regulation, and gradually develops in the direction of the high-voltage power. For the ability of achieving higher voltage levels and the advantage of outputting less harmonic content, three-level inverter has been widely used on the occasion of the high-voltage power inverter. Accompany with the vector control theory proposed, the development of electromotor control technology has entered a new phase, however, high-precision and high-resolution speed sensor not only increase the cost of the servo drive system, but also limits its applications in harsh environments for its high price. For this reason, the speed sensorless control technique attracts more and more attention.This thesis researches into vector control system of speed sensorless based on full-order observer, and also reviews three-level inverter and speed sensorless technology, as well as analyzes their advantage. In addition, it elaborates on the working principle of three-level inverter, the principle of space voltage vector control (viz. SVPWM), and the theory of coordinate transformation and induction motor slip frequency vector control system. In the study of three-level induction’s motor slip frequency vector control, theoretical calculation about the PI controller parameters, and the simulation through MATLAB/Simulink have been adopted which validate design parameters’ accuracy and good robustness. And based on the above theory, this thesis further research into vector control system based on three-level full-order observer. Through the analysis of the mathematical model of the induction motor, full-order state observer has been designed, and then pole-assigned. Moreover, using Lyapunov stability theory designs the identification speed of adaptive rate, stator resistance and rotor time constant of adaptive rate. In connection with the above design and research, simulation and verification are adopted based on three-level full-order observer vector control system through MATLAB/Simulink. It shows that the actual speed fits the estimated speed, and only has tiny inaccuracy within the allowable error range. For the system suddenly adding speed, suddenly loading, and1.5times torque at zero-velocity, it can track well and have a good dynamic performance. Meanwhile, the identified the stator resistance and rotor time constant are consistent with actual value. Likewise the inaccuracy is within the allowable error range. Finally, the last part of this thesis draws a summary of the research and gives an analysis and prospect for the future research.