Research On Optimization Of Direct Torque Control System Strategy Of Asynchronous Motor

At the end of the last century,direct torque control(DTC)has progressively become the focus of application in the field of high performance AC speed regulation after nearly two decades.Compared with vector control,flux and torque can be control straightforward,coordinate transformation is easy,nonlinear and coupling problems of vector control is solved.the structure of DTC is easy,dynamic and static response speed is fast,and robustness is good.At present,direct torque control technology has set off a large number of experts and scholars research upsurge,many teams focus on its application and improvement.Therefore,this paper focuses on the direct torque control of induction motor,starting from its basic working principle,improving its control strategy.In this paper,the structure and principle of induction motor are researched,establishing the mathematical model,we should know the working process of the direct torque control system and the basic principle,according to the induction motor torque and flux ripple larger situation,the paper use twelve sector principle in order to reduce torque and flux ripple.The design principle of hybrid model flux observer and smooth switching between models are analyzed in detail.The advantages of hybrid model in stator flux observation are obtained by comparing with the traditional stator flux observer of voltage model and current model.it is combined with Model Reference Adaptive System(MRAS)to replace the traditional Reference Model and form a new improved MRAS-DTC system.Through simulation and comparison,the waveform optimization effect of torque,speed,three-phase current is analyzed.Finally,the MRAS-DTC system has better control effect than the traditional DTC system.In this paper,the twelve-sector and hybrid model flux observer are combined with MRAS to build simulation models of the system before and after the improvement,based on dynamic and static observing the relevant waveform of the two systems.We need to build the hardware experiment platform of the system,the main program of the system software part and the interrupt service subroutine were written to verify the control effect of the new MRAS-DTC system,and the feasibility of the theory was proved.