Design And Realization Of The Speed Sensorless Vector Control System Of Induction Motor

In the high performance vector control systems of induction motor, photoelectricencoders and other speed sensors are usually used to detect speed, this not only increasesthe cost of system but also decreases the reliability of the system, so the speed sensorlesscontrol technology has become a research hotspot in the academic and engineering fieldsin recent years. In this thesis, theories were researched and physical experiments weredone, around the speed sensorless control technology and related problems.Firstly, the principle of induction motor vector control was elaborated. Two methodsof speed estimation were analyzed, the first is a direct calculation method based on thehybrid flux model, its working principle was analyzed and its regulator parameters weredesigned; the second is a method of speed adaptive full order flux observer, its workingprinciple was analyzed and a new discretization method was presented. In order todetermine which method is of better performance and more practical, thoroughcomparison experiments were carried out in saber simulation environment.In order to speed up the dynamic response and improve the load capacity of inductionmotor, the overmodulation strategy of three phase voltage source inverter was thenresearched. The equivalence of an optimized SPWM and SVPWM in the linearmodulation region was proved, and the simple and practical characteristics of theoptimized SPWM were extended to overmodulation area, its fundamental characteristicsand harmonic content in the overmodulation region were analyzed in depth. Experimentalresults show that the proposed overmodulation algorithm is simple, effective and of fewerharmonics.Finally, the drive software was designed on MB9BF506Nwhich with ARM coreinside, and the physical experiment of speed sensorless vector control system was done.Multifaceted comparative experiments of the two sensorless control schemes were carriedout. The results show that both kinds of sensorless control system have strong practicalvalue, and actual systems should choose the suitable solutions according to their owncharacteristics and needs.