Simulation Study On Online Optimization Of Vector Control For Ac Synchronous Motors

With the wide use of AC synchronous motors,especially the permanent magnet synchronous motors(PMSM)and synchronous reluctance motors(SynRM),in modern industrial production,high-efficiency control is becoming increasingly valuable.Vector control is usually utilized for synchronous motors,whilst maximum torque per ampere(MTPA)control is a common method of the vector control.Therefore,in this thesis,the MTPA control is taken as an example for the study of the high-efficiency vector control.Since the MTPA operation curves varies with different motors,say,the phase angle of the current vector is directly affected by the motor structure,the electromagnetic parameters,and the working conditions such as spread and load,the MTPA control is often designed as a customized and offline algorithm.The general online optimizing MTPA strategy which dynamiclly determines the current-vector phase angle can adapt to different motors,and is valuable for practical applications.Therefore,this paper studies the design and improment of the online optimization of MTPA algorithm is studied in this thesisFirst of all,the MTPA control principle and its mathematical model derivation are discussed in detail.Various common engineering implementation and related characteristics of MTPA are summarized and analyzed.Furthermore,online automatic optimization strategy based on virtual signal injection is deeply studied.Besides,the effects on the dynamic response capability and steady-state accuracy of the algorithm of different injected signals are analyzed and comparedConsidering the torque model error caused by the parameter variation,it is proposed to com-bine the idea of virtual signal injection MTPA-based online optimization strategy with extreme value search.An indirect extreme value search of the current vector phase angle in the MTPA con-trol is thus realized.The incremental inductance detection mechanism ensures the sensitivity of the algorithm to variable operating conditionsAfter that,based on the derivative formula of the torque to the current vector phase angle,a mathematical explanation of the modified torque reconstruction model is presented.In addition,a phase swing method with a self-starting mechanism is designed to implement the online MTPA al-gorithm.The proposed algorithm does not need additional electrical signal injection,which avoids the extra energy loss caused by the traditional real-time parameter identification.Finally,through the Matlab/Simulink simulation study,under a series of working conditions,the proposed online optimal vector control strategies are implemented for the permanent magnet synchronous motor and synchronous reluctance motor with saturation effect.The results show that the proposed methods can properly track the MTPA operating point under various operating conditions,and quick dynamic response is observed.In addition,the methods proposed in this thesis does not rely on the preset motor parameters,which extend its universality and portability.