交流电机矢量控制系统滑模变结构控制策略研究

ABSTRACTThe vector controlled AC motor drive is a multi-variable system featuring time-variant,nonlinear and strongly coupled papameters.With the addition of some nonlinear and randomfactors such as mechanical friction,vibration and large load fluctuation during its operation thesystem mathematical model is difficult to be exactly deduced.Therefore modem control theoryand advanced control strategy should be applied to overcome the above mentioned influences tomake the system robust and to improve the system performance.The method of slide-modevariable structure control is such a strategy that is characterized of low mathematical modelprecision,insensitiveness to system parameter variation and extemal disturbances,omission ofparameter identifications,fast dynamic response and easy implementation.These advantages makeit suitable to high performance vector controlled AC motor drives.The dissertation aims at theapplication of slide-mode variable structure control to vector controlled AC motor drives.An introduction is made beforehand on the conceptual basis of sliding-mode variablestructure control including its design goal,method,as well as the problems of invariability andchattering etc.The scheme of a vector controlled induction motor driving system is then analyzed,and asliding-mode structure controller is designed to overcome the drawbacks of traditional PI or PIDscheme.Aimed at the sensorless vector control of induction driving system,the study is focusedon the method of rotor speed identification by sliding mode observer.A novel variable structureMRAS observer is proposed and applied for the speed identification.The thus constructedsensorless vector controlled induction motor drive is studied by simulation.With the study on the strategy of vector control of permanent magnet synchronous motor(PMSM),a number of speed controllers based on advanced control are analyzed and asliding-mode variable structure controller for the speed control of vector controlled PMSM driveis designed.Aimed at the sensorless vector control of PMSM driving system,the study is focusedon the method of speed identification by sliding mode observer.A method for speed identificationbased on variable structure MRAS is proposed.The thus constructed sensorless vector controlledPMSM drive is studied by simulation.A laboratory platform of Ac driving system designed around TI's DSP chipTMS320LF2407A is constructed and the above mentioned control strategies are tested and studiedon it.Keywords:AC motor:Vector control:Slide-mode variable structure control:permanent magnetsynchronous motor:variable structure model reference adaptive system:speed identification