Research On Wide Speed Control Technology Of Permanent Magnet Synchronous Motor Without Position Sensor

Since the rotor of the permanent magnet synchronous motor(PMSM)does not require a power source,it has been widely used.It has the advantages of small size,light weight,high efficiency,etc.However,one of its drawbacks is the need to control the phase of the current based on the position of the rotor poles,which requires the use of a position sensor.Position sensors increase the size and weight of the motor and reduce the reliability of the system which make it impractical for some applications.Therefore,the zero-low speed and medium-speed sensorless control strategies of the interior permanent magnet synchronous motor are studied.After studying the basic mathematical model of the interior permanent magnet synchronous motor,the vector control strategy of the double-closed loop of speed and current with i_d of zero is used and the high frequency mathematical model is analyzed.It lays the foundation for the subsequent high-frequency signal injection method adopted at zero low speed.In the study of the zero-low speed sensorless control strategy,since the non-unique convergence of the rotor position generated by the traditional method and the phase delay defect caused by the filter,a high-frequency orthogonal sine and cosine signal is injected in the stationary reference frame.The method obtains a sine and cosine signal containing rotor position information by demodulating the induced high frequency current signal and a series of addition and subtraction operations.It can also eliminates the adverse effects of the filters and digital delays used,enabling precise positioning of the rotor positionIn the research of high-speed sensorless control strategy,considering the harmonic influence of inverter nonlinearity on traditional observer method,a full-order slide mode observer(SMO)method based on synchronous frequency tracking filtering is proposed.This method replaces the traditional second-order sliding mode observer with a full-order SMO to avoid the phase delay defects caused by the use of filters.The observed extended back EMF signal is filtered using a synchronous frequency function.It tracks the changing stator current and filters out harmonics that are not part of the tracking signal to achieve static tracking of the stator current.The harmonic content of the position is obviously suppressed and the rotor position error is significantly reduced.In order to verify the feasibility of the method,the model was modeled on Matlab/Simulink simulation platform,and the hardware experiment was verified by the existing interior PMSM and dSPACE semi-physical semi-simulation platform.The results show that the sensorless control method of permanent magnet synchronous motor designed in this dissertation can improve the accuracy of position observation and achieve the expected goal.