Research On Asynchronous Motor Vector Control Based On Five-level Inverter

It is one of the latest development directions of modern power electronics technology,and it is used in the vector control system of induction motor.The accurate observation of the rotor flux and the speed estimation are the key to complete the vector control of induction motor.So this article in the design,on the basis of the five level inverter of flux observer based on voltage current Model design and Model Reference Adaptive System(Model Reference Adaptive System,MRAS)speed estimation method is studied.In this paper,the control technology of multi-level inverter and the development of high voltage variable frequency control system of asynchronous motor are briefly summarized.In addition,the design and analysis of the flux observer model are proposed.Three typical multilevel inverter topologies and their working principles are introduced,and the advantages and disadvantages of each topology circuit are compared with the five-level inverter.On the basis of traditional topological structure,the paper designs an ANPC-5L inverter with an active midpoint clamping type(ANPC-5L),which overcomes many problems existing in the traditional inverter.Secondly,in this paper,the design principle and working characteristics of ANPC-5L inverter circuit are analyzed in detail,and the space voltage vector modulation(SVPWM)is selected as the modulation strategy of inverter.The algorithm is improved by coordinate transformation,and the reference voltage vector is defined based on the virtual coordinate system,which reduces a lot of complicated trigonometric functions and simplifies the calculation process of the system.Finally,the simulation model of inverter is built,and the SVPWM control of ANPC five-level inverter is verified by simulation experiment.This paper analyzes the potential fluctuation of the dc side of the five-level inverter and puts forward the method to realize the potential stability control.At the same time,the thesis also suspended capacitance in circuit for inverter of each phase voltage imbalance to do the further research,through the system of the zero sequence component control strategy for each phase suspension capacitance voltage stability control.Finally,the simulation experiment was carried out in the Simulink software environment to establish the system control model,and verified the effectiveness and feasibility of the potential balance control strategy.Finally,the motor flux observer model is further studied.Small signal model analysis is used to test the stability of the traditional voltage and current flux linkage model,and the unstable region of the model is found under the condition of motor power generation.By introducing the parameters? of the motor,the model is improved.After testing,the improved voltage and current model flux observer is used to achieve the whole system stability.In addition,the improved model of flux linkage is used as a reference model to design the speed estimation system of model reference adaptive(MRAS).A complete simulation model of asynchronous motor speed vector control system is built,and the operation effect before and after improvement is compared by experiment.