Research On The Positon Sensorless Control System Of Permanent Magnet Synchronous Motor At Low And Zero Speed Range

Permanent magnet synchronous motors (PMSM) have been widely applied inelectrical drive systems with advantages such as small size, high reliability, highpower desnity and good operating performance. High-performance position sensorlessvector control technology has always been one of the most attractive research issuesin motor control field. This dissertation takes the interior permanent magnetsynchronous motor (IPMSM) as the research object, and to achieve sensorless vectorcontrol in low and zero speed range, the extraction of rotor position information andthe fully digital control system are studied respectively in this paper.Firstly, the mathematical model of the PMSM at each coordinate system and theeffect of the motor saliency are introduced. The basic principles of vector control andits application in PMSM have been described with the giving of the correspondingsimulation results.Secondly, on the basis of establishing a mathematical model PMSM at highfrequency excitation, the basic principles of rotating and pulsating high-frequencyvoltage signal injection methods are elaborated. Estimated rotor position and speedinformation are obtained through the corresponding demodulation method. A rotorposition information extraction method based on SDFT method is introduced toimprove the estimation accuracy of the rotor position. A method for detecting theinitial position of PMSM is presented in order to achieve the applicability ofhigh-frequency signal injection method at zero speed. Simulation studies prove thecorrectness and validity of the theoretical analysis.To improve the accuracy of the rotor position estimation, this paper focuses onthe effects of inverter nonlinear on PMSM sensorless control technology. Severaltypical nonlinear characteristics of the inverter have been briefly described andanalyzed and determined the dead time effect and parasitic capacitance effects are themain factors which affect the sensorless control technology. Detailed analysis of theeffects of parasitic capacitance in the dead-time on the high-frequency carrier currentscomprising the rotor position information has been given. This paper introduces a newtype of post-compensation method and the simulation and experiment varifies thevalidity and accuracy of this method.Finally, this paper designs the sensorless vector control of PMSM experimentalplatform which based on dSPACE, and completes the experiments of the sensorlesscontrol of PMSM based on a rotating high frequency voltage signal injection method and improved rotor position extraction method based on SDFT. Experimental resultsshow that the method is effective to get the motor speed and rotor positioninformation, and the system has a good dynamic and static performance.