Research On Sensorless Control Technology Of Permanent Magnet Synchronous Motor

With the development and progress of society,permanent magnet synchronous motors(PMSMs)have been widely used in various fields because of the advantages of their simple structure,high operating efficiency,and high power density.In order to build a high-performance control system for PMSMs,detecting the rotor position and speed accurately is necessary.However,the use of mechanical sensor devices not only increases the size and cost of the system,but also reduces the reliability and stability of the system.Therefore,the research on sensorless control technology of PMSM has become the one of the most popular direction in the field of electric drive.This disserta-tion mainly discusses the research of sensorless control algorithm of permanent magnet synchronous motor at different speeds.Firstly,in order to study the sensorless control technology more efficiently,this chapter introduces the structure and type of PMSM and presents the mathematical model of the motor in the three coordinate systems of the ABC natural coordinate system,the static two-phase ?-? coordinate system and the synchronous d-q rotating coordinate system,and the transformation relationship among them.The principle and framework of id=0 vector control are also expounded in this chapter.Secondly,in view of the current sensorless control technology of PMSMs,where motor is running in the middle and high speed stage,this chapter analyzes the traditional model reference adaptive system(MRAS),and designs an adaptive full-order observer based on the superstability theory.Then,the correction term is introduced to form a closed-loop state estimation to improve the accuracy of the system model.Finally,the sliding mode controller(SMC)is used to replace the traditional PI regulator to control the speed loop.It can be seen from the simulation results that compared with the tradi-tional model reference adaptive control method,this control strategy can estimate the rotor position and speed of the motor more accurately and quickly when the motor starts,the speed changes suddenly and the load torque changes suddenly.It can be shown that the whole control system also has better anti-interference ability and better robustness.In addition,this chapter analyzes the principle of saturation salient polarity of sta-tor winding of surface-mounted PMSM,and introduces the control strategy of high frequency pulse voltage injection(HFPVI)when the PMSM is running at zero and low speed.In terms of low system stability in the high frequency signal injection method,this dissertation improves the original rotor position estimation system,and proposes a new form of modulated signal.For the case that the estimation error of rotor position and speed increases with the increase of speed,compensation of position error is designed based on the traditional method.The simulation results show that the designed new HF-PVI method can not only improve the reduction of the estimation accuracy caused by the speed increase of the motor at zero and low speed running stage,but also improve the stability and dynamic performance of the system in this case.Finally,in order to verify the proposed new sensorless control scheme,based on the laboratory motor platform,the experiments of PMSM were carried out at zero low speed and medium high speed respectively.The experimental results proved the effectiveness of the proposed control strategy.